NASA Conference Publication 3304

NASA-CP-3304 19960009401

National Educators' Workshop: Update 94

Standard Experiments in Engineering Materials Science and

Technology

Compiled by

James E. Gardner, JamesA. Jacobs,and Anna C. Fraker

......................... _ Proceedings of a workshop sponsored jointly by the

l er_ :, ;.-,-;;-, ! National Institute of Standards and Technology,

I ' ; ! Gaithersburg, Maryland, the National Aeronautics and

i. _ Space Administration, Washington, D.C., the Norfolk

, _ _ F'- State University, Norfolk, Virginia, and the United States

Department of Energy, Oak Ridge, Tennessee, and held in

Gaithersburg, Maryland

November 7-9, 1994

August 1995

Secca

! 3 1176 01422 7459

rNASA Conference Publication 3304

National Educators' Workshop: Update 94

Standard Experiments in Engineering Materials Science and

Technology

Compiled by

James E. Gardner

Langley Research Center • Hampton, Virginia

James A. Jacobs

Norfolk State University • Norfolk, Virginia

Anna C. Fraker

National Institute of Standards and Technology • Gaithersburg, Maryland

Proceedings of a workshop sponsored jointly by the

National Institute of Standards and Technology,

Gaithersburg, Maryland, the National Aeronautics and

Space Administration, Washington, D.C., the Norfolk

State University, Norfolk, Virginia, and the United States

Department of Energy, Oak Ridge, Tennessee, and held in

Gaithersburg, Maryland

November 7-9, 1994

National Aeronautics and Space Administration

Langley Research Center • Hampton, Virginia 23681-0001

August 1995
The opinions expressed in this document are not necessarily approved or endorsed by the

National Aeronautics and Space Administration.

This publication is available from the following sources:

NASA Center for AeroSpace Information National Technical Information Service (NTIS)

800 Elkridge Landing Road 5285 Port Royal Road

Lhlthicum Heights, MD 21090-2934 Springfield, VA 22161-2171

(301) 621-0390 (703) 487-4650

ii
PREFACE

NEW:Update 94 was held Novcmbcr 7 - 9, 1994, at National Institute of Standards and Technology

(NIST) in Gaithersburg, Maryland. Building on past workshops and extcnsive workshop evaluations, this

9th annual NEW:Update continued to follow the theme of strengthening materials education. Over 130

participants witnessed demonstrations of experiments, discussed issues oflnatefials science and engineering

(MS&E) with people from education, industry, government, and technical societies, heard about new

MS&E developments, and attended 3 hour mini workshops in state-of-the-art NIST laboratories.

Concurrent sessions were held in order to accommodate all of thc demonstrations of experiments. Faculty

in attcndancc represented high schools, community collcges, smaller collcgcs, and major universities.

Undergraduate mad graduate studcnts also attended.

Reprcscnting the American Socicty for Engineering Education's (ASEE) Materials Division, Dave Werstlcr

presented a special plaque to NIST personnel JoniceAdmns, Anna Frakcr. Brian Bclanger, Harry. Rook,

mad Lyle Schwartz for their valuable contributions to MS&E education through their nine years of support

to NEW:Updates and other materials education efforts. The ovenvhclming success of NEW:Updates

results in a large mcasurc from the considerable work and sacrifices of the host agencies: N1ST, NASA

Langley Research Center, Oak Ridge National Laboratory, mad Norfolk State University.

NEW:Update 94 participants aided in evaluating over thirty-five experiments that were presented before

the group. Additional updating information relating to materials science, engineering and technology was

also presented as mini plenary sessions that focuscd on technology transfer from N1ST. design with

Continuous Fiber Ceramic Composites (CFCCs),intclligent proccssing, nanostructured materials, emerging

materials technology and ASM hlternational's educational tools. We also learned about the technology

mad advantages of CD ROM for strengthening materials education and of .joint effort among ASEE.

Materials Education Council (MEC) mad NSU to develop CD ROM disks of the NEW:Updates. You will

find transparency masters for the mini plenary scssions included in this publication.

The experiments in this publication can serve as a valuable guide to faculty who arc intcrcstcd in useful

activities for their students. The material was the result of years of research aimed at better methods of

teaching materials scicncc, engineering and technology. The experiments were developed by faculty,

scientists, and engineers throughout the United States. There is a blend of cxperi|nents on new materials

and traditional matcrials. Uses of computcrs in MS&E, cxpcfimental design, and a variety of low cost

cxpcrimcnts were among the demonstrations presented. Transparcncy inastcrs of technical presentations

arc also included.

Experiments underwent an extensive peer rcvicw process. After submission of abstracts, selected authors

were notified of their acceptance and given the fonnat for submission of experiments. Experiments were

rcvicwcd by a panel of specialists through the cooperation of the Materials Education Council. Authors

rcccivcd comments from the panel prior to NEW: Update 94, allowing them to make necessary adiustments

prior to demonstrating their experiments. Comments from workshop participants provided additional

fccdback which authors used to make final rcvisions which wcrc submittcd for thc NASA editorial group

for this publication.

The Materials Education Council of the United Statcs publishes sclccted experiments in the Journal of

Material,_ Education (JOE). _c .IOE offcrs materials educators valuable teaching and curriculum aids

including instructional modules on emerging materials technology, experiments, book reviews, mad

editorials.

,°,

Iil
Vidcotapcs wcrc madc of the workshop by.'NIST with assistance from Robcrt Bcrrettini and Alfrcd E.

McKcnncy. As with previous NEW:Updatcs. critiques were made of thc workshop to provide continuing

improvcmcnt of this activity. Tbc evaluations and rccommendations madc by,participants providc valuablc

fcedback for planning of subscqucnt NEW:Updates.

NEW:Update 94 and the scrics of workshops that go back to 1986 arc. to our kno\_lcdgc, thc only

national workshops or gatherings for materials educators that havc a focus on the full rangc of issues on

stratcgics for bcttcr tcaching about thc full colnplcmcnt of matcrials. Rccognizing the problcm of

motivating young pcople to pursue carcers in MSE. we have included cxcmpla_ pre-university activities

such as Advcnturcs in Science. ASM International Education Foundations Carccr Outreach Program.

Engineers for Education. National Tcachcrs Institutc for Materials Science and Tcchnology. and scvcral

progranls run through high schools.

NEW:Update 94, with its diversity of faculty, industry, and govcmmcnt MSE participants, scrvcd as a

forum for both formal and informal issues facing MSE cducation that rangcd from thc challengcs of

keeping faculty and students abreast of new technology to idcas to insure that matcrials scicntists.

enginccrs, and technicians maintain thc proper respect for thc cnvironmcnt in thc pursuit of thcir

objectives.

NEW:Update 94 rcsultcd from considcrablc coopcrativc efforts bv individualsin govcmmcnt, education,

and industrly'. The workshop's goal is to maintain thc network of participants and to continue to collect

these idcas and resources to bring thcm together in a compendium of cxpcrimcnts in matcrials sciencc,

enginccfing and technology. Please read the paper in this book. "CD ROM Technology to Strengthcn

Matcrials Education". to learn more about cfforts to dcvclop CD ROM compcndium disks.

We hope that the cxpcrimcnts presented in tiffs publication will assist you in tcaching about materials

scicncc, cnginccdng and tcchnology. Wc would like to have your comments on their valuc and means

of improving them. Plcasc send commcnts to Jalncs A. Jacobs, School of Teclmology, Norfolk Statc

Univcrsity, Norfolk, Virginia 23504.

We express our apprcciation to all those who hclpcd to kccp this series of workshops viablc.

The use of trademarks or manufacturers"namesin thispublication doesnot constitute endorsement,

eitber expressedorimplied, by the National Aeronauticsand SpaceAdministration.

iv
MANAGEMENT TEAM

Workshop Co-Directors NASA LaRC Coordinator

Anna C. Fraker James E. Gardner

National Institute of Standards &Tcchnology National Aeronautics and Space Administration

Langley Research Center

James A. Jacobs Director's Assistant

Professor of Engineering Technology Diana P. LaClaire

Norfolk State University Norfolk State University

Committee Members

Jonice S. Adams Thomas F. Kilduff

National [nstitue of Standards & Technology Thomas Nelson Community College

Edward Aebischer David King

Oak Ridge National Laboratory Physics, National Institute of Standards

& Technology

Drew Azzara

American Society for Testing and Materials James V. Masi

Western New England College

Robert Berrettini

Materials Education Council Alfred E. McKennev

IBM Corporation. Retired

Patrice Boulanger

National Institute of Standards & Technology Curtis R Nettlcs

Battctle Pacific Northwest Laboratories

L. Roy Bmmell

Battelle Pacific Northwest Laboratories Heidi R. Ries

Norlblk State University

James A. Clum

State University of New York at Binghamton Ham L. Rook

National Institute of Standards & Technology

Douglas F. Craig

Oak Ridge National Laborato_' Robert O. Shutl

National Institute of Standards & Technology

Claudia Ford

ASM International Willie E. Spencer

Fernald Environmental Restoration Mgmt.Corp.

Laurie A. George

American Dental Association F. Xavier Spiegel

Loyola College

Linda L. Horton

Oak Ridge National Laboratories Margarct Weeks

Coming Community College

Rodnev D. Jiggetts

National Institute of Standards & Technology David Werstler

American Society Ibr Engineering Education

Norman J. Johnston

National Aeronautics & Space Administration William Winn

Depamnent of Energy

Michael ,4. Karnitz

Oak Ridge National Laboratories

v
Management Team

kvi
CONTENTS

PREFACE ................................................................................... i i i

PLANNING COMMITTEE MEMBERS .................. v

REVIEWERS OF EXPERIMENTS ......................................................... xi

NIST MINI WORKSHOPS .............................................................. xii

LISTING OF EXPERIMENTS FROM NEW: UPDATES ............................. xvii

ORDERING INFORMATION FOR ADDITIONAL RESOURCES .................. xxiii

PARTICIPANTS ....................................................................... xxvii

TECHNOLOGY TRANSFER OF NIST RESEARCH ...................................... 1

Lyle H. Schwartz - National Institute Of Standards And Technology

BULK ETCHING OF SILICON FOR MICROMACHINING and

MICROMACHINING OF SUSPENDED STRUCTURES IN SILICON ................ 39

John H. Comtois, Thomas J. Jenkins, and Victor M. Bright -

Air Force Institute Of Technology

DIMENSIONLESS FUN WITH FOAM .................................................. 67

Edward L. Widener - Purdue University

INTRODUCTION TO NONDESTRUCTIVE TESTING ............................... 73

David E. Werstler Western Washington University

PC LASER PRINTER-GENERATED CUBIC STEREOGRAPHIC PROJECTIONS

WITH ACCOMPANYING STUDENT EXERCISE ...................................... 79

Paul J. Coyne, Jr., Glenn S. Kohne, and Wayne L. Elban

Loyola College

STEREOGRAPHIC PROJECTION ANALYSIS OF FRACTURE PLANE TRACES

IN POLISHED SILICON WAFERS FOR INTEGRATED CIRCUITS ................ 101

Wayne L. Elban - Loyola College

PAPER CLIP FATIGUE BEND TEST .................................................. 123

Alan K. Karplus - Western New England College

vii
MATHEMATICS FOR ENGINEERING MATERIALS TECHNOLOGY

EXPERIMENTS AND PROBLEM SOLVING ........................................... 133

Thomas F. Kilduff - Thomas Nelson Community College

James A. Jacobs - Norfolk State University

INCORPORATING "INTELLIGENT" MATERIALS INTO

SCIENCE EDUCATION ................................................................. 145

Robert J. Scheer - Protein Solutions, Inc.

MEASURING ENERGY LOSS BETWEEN COLLIDING METAL OBJECTS ........ 159

Bernard J. Weigman and Stamos Courpas - Loyola College

STRESS CONCENTRATION: COMPUTER FINITE ELEMENT

ANALYSIS VS. PHOTOELASTICITY ................................................. 171

Vernon S. Hillsman - Purdue University

FAILURE ANALYSIS OF INJECTION MOLDED PLASTIC

ENGINEERED PARTS ................................................................... 177

Jerry L. Wickman Ball State University

Nikhil K. Kundu - Purdue University

DEMONSTRATIONS IN MATERIALS SCIENCE FROM THE CANDY SHOP .... 187

F. Xavier Spiegel - Loyola College

OPTIMIZING WING DESIGN BY USING A PIEZOELECTRIC POLYMER ....... 193

Mukul Kundu John Adams High School

Nikhil K. Kundu Purdue University

and

AN AFFORDABLE MATERIAL TESTING DEVICE .................................. 201

Nikhil K. Kundu and Jerry L. Wickman Ball State University

PHOTOCATALYTIC DESTRUCTION OF AN ORGANIC DYE USING TiOz ..... 211

Kim Giglio, John Bowling, Ben Hutchinson, and David Green -

Pepperdine University

ULTRASONIC WELDING OF RECYCLED HIGH DENSITY

POLYETHYLENE (HDPE) .............................................................. 219

Ping Lui and Tommy L. Waskom Eastern Illinois University

INTRODUCTION TO CONTINUOUS FIBER CERAMIC COMPOSITES ......... 227

William G. Long - Babcock & Wilcox Co.

DESIGNING WITH CONTINUOUS FIBER CERAMIC COMPOSITES ............ 245

Kenneth L. Reifsnider Virginia Polytechnic Institute And State University

oto

VIII
NANOSTRUCTURED MATERIALS ................................................... 289

Robert D. Shull National Institute Of Standards And Testing

DEVELOPMENT OF COURSE MODULES FOR MATERIALS EXPERIMENTS .... 321

Kristen P. Constant and Krishna Vedula - Iowa State University

TESTING SAND QUALITY IN THE FOUNDRY

(A BASIC UNIVERSITY-INDUSTRY PARTNERSHIP) .............................. 329

Donald H. Martin - Tri-State University

Hermann Schwan Auburn Foundry Group, Europe

Michael Diehm - Auburn Foundry, Inc.

OBSERVING AND MODELING CREEP BEHAVIOR IN WOOD ................... 343

Thomas M. Gorman - University Of Idaho

THE DEVELOPMENT OF MECHANICAL STRENGTH IN A

CERAMIC MATERIAL DURING FIRING ............................................ 351

L. Roy Bunnell - Battelle Pacific Northwest Laboratories

Steven W. Piippo Richland High School

WATER DROP TEST FOR SILVER MIGRATION ................................... 361

Ted Gabrykewicz Hocking College

INEXPENSIVE EXPERIMENTS IN CREEP AND RELAXATION OF POLYMERS ... 367

Kopl Halperin, Charles Eccles, and Brett Latimer -

Pennsylvania State University Behrend

CONCRETE REPAIR APPLICATIONS ................................................ 379

Leonard W. Fine - Columbia University in the City of New York

GLASS FRACTURE EXPERIMENT FOR FAILURE ANALYSIS ..................... 387

Charles V. White GMI Engineering and Management Institute

IMPACT OF FLAWS ................................................................... 395

JoDee Daufenbach and Alair Griffin Lone Peak Engineering

STUDYING MACROSCOPIC YIELDING IN WELDED ALUMINUM

JOINTS USING PHOTOSTRESS ...................................................... 403

Kishen Kavikondala and S. C. Gambrell, Jr. - University of Alabama

BUBBLE RAFTS, CRYSTAL STRUCTURES, AND COMPUTER ANIMATION ... 413

James V. Masi - Western New England College

IN-CLASS EXPERIMENTS: PIANO WIRE AND POLYMERS ....................... 421

• David Stienstra Rose-Hulman Institute Of Technology

ix
DIELECTRIC ANALYSIS OF POLYMER PROCESSING ............................. 429

Kris Kern And Heidi R. Ries - Norfolk State University

CRYSTAL MODELS FOR THE BEGINNING STUDENT:

AN EXTENSION TO DIAMOND CUBIC ............................................. 439

Harvey A. West North Carolina State University

F. Xavier Spiegel - Loyola College

TRANSFERRING KNOWLEDGE TO THE SHOP FLOOR ........................... 451

J. K. Brimacombe - The University Of British Columbia

UNDERSTANDING PHASE DIAGRAMS ............................................. 471

Patricia J. Olesak - Purdue University

PRECISION MEASUREMENTS OF THE MICROWAVE DIELECTRIC

CONSTANTS OF POLYVINYL STEARATE AND POLYVINYLIDENE

FLUORIDE AS A FUNCTION OF FREQUENCY AND TEMPERATURE ........... 479

Jai N. Dahiya - Southeast Missouri State University

EXPLORING THE CRYSTAL STRUCTURE OF METALS ........................... 495

Richard P. Krepski - Intermet Technology

FLUIDS WITH MAGNETIC PERSONALITIES ....................................... 503

Glenn S. Kohne - Loyola College

CD-ROM TECHNOLOGY TO STRENGTHEN MATERIALS EDUCATION ....... 5 1 1

Alfred E. McKenney and Evelyn D. McKenney - Consultants

Robert Berrettini - Materials Education Council

EFFECTS OF RISERS ON CAST ALUMINUM PLATES ............................. 525

H. T. McClelland - University Of Wisconsin - Stout

EMERGING MATERIALS TECHNOLOGY ............................................ 535

Harris M. Burte

ASM EDUCATIONAL TOOLS NOW AND INTO THE FUTURE .................. 553

Robert Uhl ASM International

DENSITY BY TITRATION ............................................................. 571

Raymond Bruzan Lanphier High School

Douglas Baker - Springfield Plastics, Inc.

X
REVIEWERS FOR NEW:Update 94

Else Breval Susan Hoyle

Senior Research Associate Research Associate

Materials Research Laboratory Materials Research Laboratory

Pennsylvania State University Pennsylvania State University

Witold Brostow M.N. Kallas

Professor of Materials Science Assistant Professor of Mechanical

Center for Materials Characterization Engineering

University of North Texas Pennsylvania State University

William Callister Raafat Malek

Associate Professor of Materials Science and Research Associate

Engineering lntercollege Materials Research Laboratory

University of Utah The Pennsylvania State University

Wenwu Cao Herbert McKinstry

Senior Research Associate Associate Professor of Materials Science (ret.)

Materials Research Laboratory Intercollege Materials Research Laboratory

Pennsylvania State University The Pennsylvania State University

Jeffrey Csernica Clayton Ruud

Assistant Professor Professor

Chemical Engineering Industrial and Management Systems Engineering

Bucknell The Pennsylvania State University

Theodore Davidson Barry Scheetz

Professor Professor of Materials Science

Polymer Processing Institute lntercollege Materials Research Laboratory

Stevens Institute of Technology The Pennsylvania State University

Renatta S. Engel Susan Trolier-McKinstry

Assistant Professor Assistant Professor

Engineering Science and Mechanics lntercollege Materials Research Laboratory

Pennsylvania State University The Pennsylvania State University

Joseph Giachino David Werstler

Program Manager, Technology Dept. Professor

Electronics Division Engineering Technology Department

Ford Motor Co. Western Washington University

Michael Grutzeck

Associate Professor

lntercollege Materials Research Laboratory

Pennsylvania State University

Technical notebooks and announcements of the workshop were provided by

NASA LANGLEY RESEARCH CENTER

xi
NIST MINI WORKSHOPS

• Intelligent Processing of Materials - Building 231, Room 8154

Stephen D. Ridder, Frank Biancaniello, Michael Zachariah, and Rodney Jiggetts

State of the art computer systems are used in metallurgical processessuch as gas atomization, and image

aJlalysis. Control. feedback and analysis will be presented.

• Automated Manufacturing Research Facility - Building 304 AMRF/Shop Floor

Denver Lovett

Shops of Future Manufacturing - This workshop will explore the role of information technology and

multimedia in developing high pcrfonnance training systems for nmnufacturing.

• Ceramic Materials by Design - Building 223, Room A-258

John Blendell and Carol Handwerker

Use of high tcclmology ceramic materials requires carefully controlled processing in order to exploit their

unique properties. The relationship between ceramic microstructure and properties will be described as

well as processing routes to control microstructurc.

• Growth, Fabrication and Testing of Novel Semiconductor Devices - Building 221, Room A 151

Curt Richter

It will be shown how semiconductors are grown by molecular beam epitaxy techniques and then are

fabricated into spccialized devices and tested.

• Magnetic Nanocomposites - Building 223, Room B 143

Joseph Ritter and Robert D. Shull

Preparation madproperty measurement of composites with constituents only a few nanometers will be

demonstrated.

• Polymer Composites - Building B 224, Room A 210

Donald Hunston

Methods of reducing fabricationcosts and basic studiesof degradationmechanisms for life prediction will

be presented.

• Optical Tweezers - Building 221, Room A-164

Kristian Helmerson

Tightly focuscd beams of laser light can be used to remotely manipulate microscopic objects, including

biological material. Such optical traps, comnaonly referred to as "optical twcezers" hold great promise

for noninvasivc naicromanipulation madmechanical naeasurcmcnt in biology.

• X-ray Optics and Multilayer Microstructures: Design, Production, Testing and Applications -

Building 221, Room A-246 and A-47

Joseph Pedulla, Richard Watts, Thomas Lucatorto, and Richard D. Deslattes

Provides a view of a new tcchnology: the fabrication of soft x-ray mirrors by deposition of multilaver

microstructurcs. Nommlly. soft x-rays arc absorbed when incident upon material surfaces. By careful

design and deposition of alternate layers of high density and low density materials, one can exploit subtle

interference effects to achieve remarkable reflcctivities throughout the range of 9-20 nm wavelength.

Discussion of how these mirrors are constructed, evaluated, madapplied in various situations.

xii
Plasma Processing of Materials - Building 221, Room A-366

James R. Roberts

Utilizing thc GEC rf rcfcrcncc cell as an cxpcrimcntal platfom_, invcstigations of plasma conditions in this

rcproduciblc sourcc arc brought to bear on proccss control. Corrclation of optical cmission spectroscopy

and lascr induccd fluorcsccncct may providc a simplc plasma rcproducibility and stability inonitor for

semiconductor etching.

Surface Analysis - Building 222, Room B-133

Dale Newbury

Microscopes bascd on borons of clcctrons, ions, or photons provide high rcsolution morphological

visualization (to nanomctcr scales) combined \vith elemental mad molecular analysis. Thcsc techniques

arc used to characterize thc microstructurc of mattcr and to elucidate processes fundamental to the physical

and biological scicnccs as \_cll as to technology.

Light Scattering from Optical Materials - Building 220 (Metrology) Room A-320

Clara Asmail

Thc way in which a surfacc scattcrs incidcnt light rcvcals information about thc microroughncss of thc

surfact topography. Thc bidirectional rcflcctancc distribution function (BRDF). Industrial applications

of BRDF will bc explored

* Mechanical Testing - Building 202, High Bay Area

Richard Field

A rcvicw of mcchanical tcsting and mechanical properties of materials will bc given Detailcd discussion

will bc givcn of testing donc at thc NIST on small spccimens that are tested in the transmission electron

microscopc and on largcr specimens that arc tcstcd in thc 12 million pound (53MN) test facility

* Industrial Radiation Processing - Building 245, Room C-209

Marc F. Desrosiers, William L. McLaughlin, and Marion L. Walker

An overview with demonstration will bc given on ionizing radiation and how it is used in indust_'.

including foods, medical devices, drugs, wastes, ctc and thc role of NIST's mcasurcmcnt services.

* National Facility Tour: Cold Neutron Research Facility - Building 235, Lobby

Henry Prask

Instmmcntation. rcprcscntativc mcasurcnacnts and infonnation on how qualificd mcmbcrs of the scicntific

community could usc thc facility \viii bc presented

* Development and evaluation of Dental Adhesive Materials - Building 224, Room A-149

Laurie George

The dcvclopmcnt of dental adhcsivcs uscd to bond dental rcstorativc matcrials to tccth involvcs thc

application of orgmfic chemistry', analytical tcsting, physical testing, and biological testing

* SQUID - Building 101, Lecture Room D

Richard Kerchner

Construction of an easily produced Superconducting Quantum Intcrfcrcnce Device and dcmonstrations both

of its sensitivity to magnctic fields and its uscfulncss as an clcctronic logic component

Io,

XIU
Mini Workshops

xiv
Mini Workshops

XV

LISTING OF EXPERIMENTS FROM NEW:UPDATES

EXPERIMENTS & DEMONSTRATIONS IN STRUCTURES, TESTING, AND EVALUATION

NEW:Update 88 NASA Conference Publication 3060

Sastri. Sankar. "Fluorescent Penetrant Inspection"

Sastri. Sankar. "Magnetic Particle Inspection"

Sastri, Sankar. "Radiographic Inspection"

NEW:Update 89 NASA Conference Publication 3074

Chowdhu%',Mostafiz R. and Chowdhu_,, Farida. "Experimental Detemainationof MaterialDamping

Using Vibration Analyzer"

Chung, Wenchiang R. "The Assessment of Metal Fiber Reinforced Polymeric Composites"

Stibolt, Kenneth A. "Tensile and Shear Strength of Adhesives"

NEW:Update 90 NIST Special Publication 822

Azzara, Drew C. "ASTM: The Dcvelopment and Application of Standards"

Bates, Seth P. "Charpy V-Notch ImpactTesting of Hot Rolled 1020Steel to Explore Temperature Impact

Strength Relationships"

Chowdhury, Mostafiz R. "A Nondestructive Testing Method to Detect Defects in Structural Mcmbers"

Comwell, L. R., Griffin, R. B., and Massarwch,W. A. "Effect of Strain Rate on Tcnsile Properties of

Plastics"

Gray, Stcphanic L.. Kern, Kristcn T., Harrics. Wynford L., and Long. Shcila Ann T.

"hnprovcd Tcclmiquc for Mcasuring Coefficients of Thcmml Extension for Polymer Fihns"

Halperin, Kopl. "Design Proiect for the MaterialsCoursc: To Pick the Best Material for a Cooking Pot"

Kundu, Nikhil. "Environmental Stress Cracking of Rccycled Themaoplastics"

Panchula, Larry and Patterson, John W. "Demonstration of a Simple Screening Strategy for Multifactor

Experiments in Engineering"

Taylor, Jenifcr A. T. "How Docs Change in Tcmpcraturc Affect Rcsistzmcc?"

Wickman, Jerry.L. and Corbin. Scott M. "Dctcnnining the Impact of Adjusting Temperature Profiles on

Photodcgradability of LDPE/Starch Blown Film"

Widener. Edward L. "It's Hard to Test Hardncss"

Widcner, Edward L. "Unconventional lmpact-Toughncss Experiments"

NEW:Update 91 NASA Conference Publication 3151

Bunnell, L. Roy. "Tcmpcrcd Glass and Thcmml Shock of Ceramic Matcrials"

Lundecn. Calvin D. "Impact Testing of Welded Samples"

Gomaan, Thomas M. "Designing, Engineering, madTesting Wood Structures"

Strchlow, Richard R. "ASTM -Tcnninology for Experimcnts and Testing"

Karplus, Alan K. "Dctennining Significant Matcrial Properties, A Discovcry Approach"

Spiegel, F. Xavier and Wcigman. Bcrnard J. "An Automatcd System for Crccp Testing"

Dcnton, Nancy L. and Hillsman, Vernon S. "lsotropie Thin-Walled Pressure Vessel Expcriment"

Allen, David J. "Stress-Strain Characteristics of Rubber-Like Materials: Experiment and Analysis"

Dahl, Charles C. "Computcr Integrated Lab Testing"

Comwell, L. R. "Mechanical Properties of Brittle Material"

xvii
NEW:Update 92

Bunncli, L. Roy. "Temperature-Dependent Electrical Conductivity of Soda-Lime Glass madConstruction

and Tcsting of Simple Airfoilsto Demonstrate Structural Design. MaterialsChoice. and Composite

Conccpts"

Marpct, Mark I. "Walkway Friction: Experiment and Analysis"

Martin, Donald H. "Application of Hardness Testing in Foundry Processing Operations: A University and

Industry Partnership"

Masi, James V. "Experiments in Corrosion for Younger Students By and For Older Students"

Nccdhanl, David. "Micropipct Manipulation of Lipid Membranes: Direct Measurement of the Material

Propcrtics of a Cohcsive Structure That is Only Two Molecules Thick"

Pcrkins, Stcvcn W. "Dircct Tcnsion Experiments on Compacted Granular Materials"

Shih, Hui-Ru. "Development of an Experimental Method to Determine the Axial Rigidity Of a

Strut-Node Joint"

Spicgcl, F. Xavicr. "An Automated Data Collection Systcm For a Charpy Impact Tester"

Tipton, Stcvcn M. "A Miniaturc Fatiguc Tcst Machinc"

Widener, Edward L. "Tool Grinding and Spark Tcsting"

NEW:Update 93 NASA Conference Publication 3259

Borst, Mark A. "Dcsign and Construction of a Tcnsilc Tester for thc Testing of Simplc Composites"

Clum. Janlcs A. "Developing Modules on Experimental Design and Process Characterization for

Manufacturing/Materials Processes Laboratories"

Dillcr, T. E. and A. L. Wicks, "Measurement of Surface Hcat Flux and Tcmpcraturc"

Denton, Nancy and Vernon S. Hiilsman. "An Introduction to Strcngth of Materials for Middle School and

Bcyond"

Fisher, Jonathan H. "Bridgman Solidification and Experiment to Assess Boundaries and Interface Shape"

Gray, Jcnnifcr "Symmctry and Structurc Through Optical Diffraction"

Karplus, AlmaK. "Knotty Knots"

Kohnc, Glenn S. "An Automated Digital Data Collcction and Analysis System for the Charpy Impact

Tcstcr"

Olcsak, Patricia J. "Sclcroscopc Hardness Testing"

Spcigcl. F. Xavicr, "hnncxpcnsivc Materials Scicncc Demonstrations"

Wickman, J. L. "Plastic Part Design Analysis Using Polarized Filters and Bircfringencc"

Widcncr. Edward L. "Tcsting Rigidity by Torque Wrench" "

EXPERIMENTS & DEMONSTRATIONS IN METALS

NEW:Update 88 NASA Conference Publication 3060

Nagy, James P. "Sensitizationof Stainless Steel"

Neville, J. P. "Crystal Growing"

Pond, Robert B. "A Demonstration of Chill Block Melt Spinning of Metal"

Shull. Robert D. "Low Carbon Steel: Metallurgical Structure vs. Mechanical Properties"

NEW:Update 89 NASA Conference Publication 3074

Balsamel, Richard. "The Magnctization Process - Hystcresis"

Bcardmore, Peter. "Future Automotive Materials - Evolution or Revolution"

Bunnell, L. Roy. "Hands-On Thermal Conductivity and Work-Hardening and Annealing in Metals"

Kazcm, Sayycd M. "Thermal Conductivity of Metals"

Nagy, Janacs P. "Austcmpcring"

toe

XVIII
NEW:Update 90 NIST Special Publication 822

Bates, Scth P. "Charp.vV-Notch Impact Testing of Hot Rolled 1020 Steel to ExploreTemperature Impact

Strength Relationships"

Chung, Wcnchiang R. and Morsc, Margery L. "Effect of Heat Treatment on a Metal Alloy"

Rastani, Mansur. "Post Heat Treatment in Liquid Phase Sintcred Tungsten-Nickel-Iron Alloys"

Spiegel, F. Xavicr. "Crystal Models for the Beginning Student"

Yang, Y. Y. and Stang, R. G. "Measurement of Strain Rate Sensitivity in Metals"

NEW:Update 91 NASA Conference Publication 3151

Cowan, Richard L. "Be-Cu Precipitation Hardening Experiment"

Kazcm, Sayyed M. "Elementary Metallography"

Krcpski, Richard P. "Experiments " " with the Low Melting Indium-Bismuth Alloy System"

Lundcen, Calvin D. "Impact Testing of Welded Sanaplcs"

McCoy, Robert A. "Cu-Zn Binary PliaseDiagram and Diffusion Couples"

Patterson, John W. "Demonstration of Magnetic Domain Boundat3' Movement Using an Easily

Assembled Videocam-Microscopc System"

Widener, Edward L. "Heat-Treating of Materials"

NEW:Update 92

Dahiya, Jai N. "Phase Transition Studies in Barium and Strontium Titanates at Microwave

Frequencies"

Rastani, Mansur. "Improved Measurement of Thcmaal Effects on Microstructure"

Walsh, Daniel W. "Visualizing Weld Metal Solidification Using Organic Analogs"

NEW:Update 93 NASA Conference Publication 3259

Guichelaar, Philip J. "The Anisotrophy of Toughness in Hot-Roiled Mild Steel"

Martin, Donald H. "From Sand Casting TO Finished Product (A Basic University-Industry Partnership)"

Petit, Jocelyn I. "New Developments in Aluminum for Aircraf_ and Automobiles"

Smith, R. Carlisle "Crater Cracking in Aluminum Welds"

EXPERIMENTS & DEMONSTRATIONS IN POLYMERS

NEW:Update 89 NASA Conference Publication 3074

Chung, Wcnchiang R. "The Assessment of Metal Fiber Reinforced Polymeric Composites"

Greet, Richard aaldCobaugh, Robert. "Rubbcrlike Elasticity Experiment"

Kern, Kristen T., Harries, Wynford L., and Long, Sheila Ann T. "Dynamic Mechanical Analysis of

Polymeric Materials"

Kundu. Nikhil K. and Kundu, Malay. "Piezoelectric and Pyroelectric Effects of a Crystalline Polymer"

Kundu, Nikhil K. "The Effect of Thcmml Danaage on the Mechanical Properties of Polymer Regrinds"

Stibolt, Kenneth A. "Tensile and Shear Strength of Adhesives"

Widener, Edward L. "Industrial Plastics Waste: Identification and Segregation"

Widener, Edward L. "Recycling Waste-Paper"

xix
NEW:Update 90 NIST Special Publication 822

Brostow. Witold and Kozak, Michael R. "Instruction in Processing as a Part of a Course in Polymer

Science and Engineering"

Comwell, L. R., Griffin, R. B., and Massarweh. W. A. "Effect of Strain Rate on Tcnsiic Properties of

Plastics"

Gray, Stcphanic L., Kern, KristcnT., Harries, Wynford L., and Long, Sheila Ann T. "hnprovcd Tccimique

for Measuring Coefficients of Thermal Extension for Polymer Fihns"

Humble, Jeffrey S. "Biodegradable Plastics: An Informative Laboratory Approach"

Kundu, Nikhii. "Environmental Stress Cracking of Recycled Tlaennoplastics"

Wickman, Jerry"L. and Corbin, Scott M. "Determining the Impact of Adjusting Temperature Profiles on

Photodcgradability of LDPE/Starch Blown Film"

NEW:Update 91 NASA Conference Publication 3151

Allen, David J. "Stress-Strain Characteristicsof Rubber-LikeMaterials: Experiment and Analysis"

Chowdhury. Mostafiz R. "An Experiment on the Use of Disposable Plastics as a Reinforcement in

Concrete Bcanls"

Gorman, Thomas M. "Designing, Engineering, and Testing Wood Structures"

Lloyd, Isabel K., Kolos, Kimberly R., Mencgaux, Edmond C., Luo, Huy, McCuen, Richard H., and

Rcgan, Thomas M. "Structure, Processing and Properties of Potatoes"

McClelland, H. T. "Laboratory Experiments from the Toy Store"

Sorensen. Carl D. "Measuring the Surface Tension of Soap Bubbles"

Wickman, Jerry L. and Plocinski, David. "A Senior Manufacturing Laboratory for Determining Injection

Molding Process Capability"

NEW:Update 92

Kundu, Nikhil K. "Performance of Thermal Adhesives in Forced Convection"

Liu, Ping. "Solving Product Safety Problcm on Recycled High Density Polyethylene Containe?"

Wickman, Jerry L. "Tllcrmofomaing From a Systems Viewpoint"

NEW:Update 93 NASA Conference Publication 3259

Csemica, Jeffrey "Mechanical Propertiesof CrosslinkedPolymer Coatings"

Edblom. Elizabeth "Testing Adhesive Strength"& "Adhesives The Stateof the Industry"

Elban, Wayne L. "Three-Point BendTesting of Poly (Methyl Mcthacrylate)and BalsaWood"

Labana. S. S. "Rccycling of Automobiles an Overview"

Liu. Ping and Tommy L. Waskom, "Application of Materials Database (MAT.DB>) to Materials

Educationand LaminatedThermoplastic CompositeMaterial"

Marshall,John A. "LiquidsThat Take Only Millisecondsto Turn into Solids"

Quaal, Karen S. "Incorporating Polymeric Materials Topics into the Undergraduate Chemistry Cor

Curriculum: NSF-Polyed Scholars Project: Microscale Synthesis and Characterization

of Polystyrene"

EXPERIMENTS & DEMONSTRATIONS IN CERAMICS

NEW:Update 88 NASA Conference Publication 3060

Nelson, Janles A. "Glassesand Ceramics: Making andTesting Superconductors"

Schull, Robert D. "High To Superconductors: Are They Magnetic?"

XX
NEW:Update 89 NASA Conference Publication 3074

Beardmore, Peter. "FutureAutomotive Materials- Evolution or Revolution"

Bunncll, L. Roy. "Hands-OnThermal ConductivityandWork-HardeningandAnncaling in Metals"

Link, Bruce. "Ccranlic Fibers"

Nagy, JamesP. "Austempefing"

Ries, Heidi R. "Dielectric Determinationof the Glass Transition Temperature"

NEW:Update 90 NIST Special Publication 822

Dahiya, J. N. "Dielectric Behaviorof Superconductorsat Microwave Frequencies"

Jordan, Gaff W. "Adapting Archimedes" Method for Detennining Densities and Porosities of Small

CeramicSanlples"

Snail, Keith A., Hanssen,LeonardM., Oakes, David B., and Butler,JamesE. "Diamond Synthesis with

a CommercialOxygen-AcetyleneTorch"

NEW:Update 91 NASA Conference Publication 3151

Bunneil, L. Roy. "Tempered Glass and Tbemml Shock of Ceranlic Materials"

Craig, Douglas F. "StructuralCeramics"

Dahiya, J.N. "Dielectric Behavior of Semiconductorsat MicrowaveFrequencies"

Weiser. Martin W:, Lauben, David N., and Madrid, Philip. "Ccranfic Processing: Experimental

Design and Optimization"

NEW:Update 92

Bunncll, L. Roy. "Temperature-Dependent Electrical Conductivity of Soda-Lime Glass"

Hcnshaw, John M. "Fracture of Glass"

Stephan. Patrick M. "High Thcmaal Conductivity of Diamond"

Vanasupa, Linda S. "A $.69 Look at Themloplastic Softening"

NEW:Update 93 NASA Conference Publication 3259

Bunnell, L. Roy and Stephen Piippo, "Property Changes During Firing of a Typical Porcelain Ccranaic"

Burchell, Timothy D. "Developments in Carbon Materials"

Dahiya, J.N., "Dieletric Measurements of Selected Ceramics at Microwave Frequencies"

Kctron, L.A. "Preparation of Simple Plaster Mold for SLip Casting and Slip Casting"

Masi, JanaesV. "Experiments in Dianlond Film Fabrication in Table Top Plasma Apparatus"

Wcrstler, David E. "Microwave Sintcring of Machining Inserts"

EXPERIMENTS & DEMONSTRATIONS IN COMPOSITES

_lEW:Update 88 NASA Conference Publication 3060

'qelson, Janles A. "Composites: Fiberglass Hand LaminatingProcess"

_IEW:Update 89 NASA Conference Publication 3074

Beardmore, Peter. "Future Automotive Materials- Evolution or Revolution"

_hung, Wenchiang R. "The Assessmentof MetalFiber Reinforced Polymeric Composites"

_olcman, J. Mafio. "Using Tcmplatc/HotwireCuttingto DemonstrateMoldlessComposite Fabrication"

NEW:Update 90 NIST Special Publication 822

Bunnell. L. R. "Simple Stressed-Skin CompositesUsing Paper Reinforcement"

Schmenk, Myron J. "Fabricationand Evaluationof a Simple CompositeStructuralBeam"

West, Harvey A. and Sprecher, A. F. "Fiber Reinforced CompositeMaterials"

xxi
NEW:Update 91 NASA Conference Publication 3151

Greet, Richard J. "Composite Columnof CommonMaterials"

NEW:Update 92

Thornton, H. Richard. "MechanicalPropertiesof Composite Materials"

NEW:Update 93 NASAConferencePublication3259

Masters,John "ASTM Methodsfor CompositeCharacterizationand Evaluation"

Wcbber, M. D. and Harvey A. West. "Continuous Unidirectional Fiber Reinforced Composites:

Fabricationand Testing"

EXPERIMENTS & DEMONSTRATIONS IN ELECTRONIC MATERIALS

NEW:Update 88 NASA Conference Publication 3060

Sastri, Sankar._ "MagneticParticle Inspection"

NEW:Update 89 NASA Conference Publication 3074

Kundu, Nikhil K. and Kundu,Malay. "Piezoelectricand PyroelectficEffects of a Crystalline Polymer"

Molton, Peter M. and Clarke. Clayton. "Anode Materialsfor ElectrochemicalWaste Destruction"

Ries, Heidi R. "Dielectric Determinationof the GlassTransitionTemperature"

NEW:Update 90 NIST Special Publication 822

Dahiya, J. N. "Dielectric Behavior of Superconductorsat Microwave Frequencies"

NEW:Update 91 NASA Conference Publication 3151

Dahiya, J. N. "Dielectric Behavior of Semiconductorsat Microwave Frequencies"

Patterson,JohnW. "Demonstrationof MagneticDomainBoundaryMovementUsinganEasily Assembled

Videocam-MicroscopeSystem"

NEW:Update 92

Bunncll, L. Roy. "Temperature-DependentElectricalConductivityof Soda-Lime Glass

Dahiya,Jai N. "PhaseTransition Studiesin Bariumand StrontiumTitanatesat Microwave Frequencies"

EXPERIMENTS & TOPICS IN MATERIALS CURRICULUM

NEW:Update 93 NASA Conference Publication 3259

Bright, Victor M. "Simulation of MaterialsProcessing: Fantasyor Reality'?"

Diwan, Ravinder M. "Manufacturing Processes Laboratory Prqjects in Mechanical Engineering

• Curriculum"

Kundu, Nikhil K. "Graphing Techniques for Materials Laboratory Using Excel"

McClelland, H. T. "Process Cability Determination of New and Existing Equipment and Introduction to

Usable Statistical Methods"

Passck, Thomas "University Outrcach Focused Discussion: What Do Educators Want From ASM

International"

xxii
ORDERING INFORMATION FOR ADDITIONAL RESOURCES

Twenty copies of the NAT|ONAL EDUCATORS' WORKSHOP PUBLICATIONS

(NASA-CPs from 1988 - 1994) are available on a first come, first served basis from

Dr. James A. Jacobs

Department of Technology

Norfolk State University

2401 Corprew Avenue

Norfolk, VA 23504

NASA publications may be ordered from

National Technical Information Center (NTIS)

Attention: Document Sales

5285 Port Royal Road

Springfield, VA 22161

or

National Center for Aerospace Information (CASI)

P. O. Box 8757

Baltimore, MD 21240-0757

BOB POND'S "FUN IN METALS" TAPE - AVAILABLE FROM

Johns Hopkins University

Maryland Hall 2 !0

3400 N. Charles Street

Baltimore, MD 21218

Cost = $30.00

QoJ

XXIII
JOURNAL OF MATERIALS EDUCATION SUBSCRIPTIONS:

JME has two categories of subscription: Institutional and Secondary. The institutional

subscription -- for university departments, libraries, government laboratories, industrial, or other

multiple-reader agencies is $250.00 (US$) per year. Institutional two-year subscriptions are

$398.00 (US$). When the institution is already a subscriber, secondary subscriptions for

individuals and subdivisions are $45.00 (US$). (Secondary subscriptions may be advantageous

where it is the desire to preserve one copy for reference and cut up the second copy for ease of

duplication.) Two-year subscriptions for secondary for individual or subdivision are $75.00

(US$). Back issues of JME are $35 (US$).

Other Materials Education Council Publications available :

Classic Crystals: A Book of Models - Hands-on Morphology. Twenty-Four Common Crystal

models to assemble and study. Aids in learningsymmetry and Miller indices. $19.00.

A Set of Four Hardbound Volumes of Wood Modules - The Clark C. Heritage Memorial

Series. Published by MEC in cooperation with the U.S.Forest Products Laboratory, Madison,

Wisconsin. A compilation of nine modules entitled Wood: Its Structure and Properties(I),

edited by Frederick F. Wangaard. A compilation of eight modules especially developed for

architects and civil engineers entitled Wood As A Structural Material (II). Also, Adhesive

Bonding of Wood and Other Structural Materials II1 and Wood: Engineering Design Concepts

(IV). Each of the first threi: wood volumes costs $29.00; the fourth volume costs $39.00. The

entire four-volume set is only $ 120.00 plus $3.50 shipping ($5.50 overseas).

The Crystallography Course - MEC's popular nine-unit course on crystallography. $37.00.

Instructional Modules in Cement Science - Five units prepared for civil engineering and

ceramic materialsscience studentsand professionals. $18.00.

Laboratory Experiments in Polymer Synthesis and Characterization - A collection of fifteen

peer-reviewed, student-tested,competency-basedmodules. $23.00. Topics include: bulk

polycondensation and end-group analysis, interracial polycondensation, gel permeation

chromatography, x-ray diffraction andothers.

Metallographic Atla_ - Royal Swedish Institute of Technology. $31.00. A brief introduction

to the microstructures of metallic materials - how they appear and how they can be modified.

Please add $2.50 per book shipping charge.

Checks payable to The Pennsylvania State University

Managing Editor, JME

110 Materials Research Laboratory

The Pennsylvania State University

University Park, PA 16802

xxiv
Workshop Location

XXV
Row O (I, to R)- S Brown. H Rejali, R Stover, A Karplus, I' Pilgrim. A .Taylor. P. Ri~ssell, S. Ajumobi, A. McKenney. B 

Berrettini, G. Selvadurav, D Barrett. 1st Row: D. Werstler. D hlartin. W Elban. D. I>aClaire, K Khan. hl. Khan, T. McClelland. 

J hloore, A. Fraker. J. ~acobs, W Lassiter, K. Simmons, J [laynes. S Joyner, J Dahiya, L Fine. 2nd Ro\\. A Pierce, E. .4ebischer. 

J. Wright, hl Webber, S. Foster. P St. John, T. Gabrykewicz, F1. West, J flillsman, P Olesak, C Noct, T. Waskom 3rd Rou 

R Krepski. J Adams. L Regel 4th Row: E. hlcKenney, K Forland, T Davidson, R. Kerchner. R. Schull, B Wilcox, T Kilduff, 

R Sctieer, hl. Gatling, S. Lin, C. Little, S. Piippo. T.,Arthur, J Branch. 5th Row. D Fisher. hl. Baker, G. Skena, C Alderman. 

hl Uz. K Brimacornbe, B. Weigman, M. Forrest, X Spiegel, E LVidener. K Constant 6th Row J hlcKenney, R Diez. P I..iu. 

G Scott. T Jenkins, J Nagy, T Spencer. A. Augustson. G flenderson. J lppolito, P Coyne, G Kohne, T Gorrnan. J Jablonski. 

R llcmard. Jr, K Schulz, C Stinespring, R. Bunnell. J Daufenbach. C Stenyer. J hlasi. D Stienstra, C [lorton 
NATIONAL EDUCATORS' WORKSHOP 1994

Participants

Jonicc S. Adams Robert Berrettini

NIST Materials Education Council

Pennsylvania State University

Edward Acbischer 110 Materials Research Laboratory

Manager, University madEducational Programs University Park, PA 16802

Martin Marietta Energy System. Inc. 814-865-1643

PO Box 2008

Oak Ridge. TN 37831 Frank Biancaniello

615-574-7717 NIST

Samuel Ajumobi John Blendell

Department of Technology NIST

Elizabeth City State University

Campus Box 866 Patrice Boulanger

Elizabeth City, NC 27909 National Institute of Standards and

Technology

Cheryl S. Alderman Gaithersburg, MD 20899

NCSU Engineering Programs at UNCA 301-975-3882

UNCA 303 RBH

One University Heights Jerry Branch

Ashville. NC 28804 Norfolk State University

704-251-6640

J.K. Brimacombe

Toni Arthur Alcan Chair in Materials Process Engineering

Norfolk State University The Center for Metallurgical Process Engr.

The Univcrsity of British Columbia

Clara Asmaii 309-6350 Stores Road

NIST Vancouver, B.C. Canada V6T IZ4

604-822-3667

Alan Augustson

Norfolk Statc University Scott Brown

Ocean Lakes High School

Mia Baker Virginia Beach Public Schools

Norfolk State University

L. Roy Bunneii

Dcmcko Barrett Senior Research Engineer

Norfolk State University, Materials Science Department

Battelle Pacific Northwest Laboratories

Antwong L. Bcrkley P.O. Box 999

Norfolk State University Richland, WA 99352

509-376-2799

xxvii
Harris Burte, Chief Scientist Theodore Davidson

WL/ML 109 Poe Road

Building 653 Princeton. NJ 08540

2977 P Strcct. Suite One 6(19-924-6146

Wright-Patterson Air Force Base

OH 45433-7734 Richard D. Deslattes

513-255-2738 NIST

Rcginald Bush Marc F. Dcsrosiers

Norfolk State University NIST

Christine Caldwcll C. Ray Diez

NASA - Langley Research Center University of North Dakota

Building 1219, Room 216 Box 7118

Hampton, VA 23665-0001 Dept. of Industrial Technology

804-864-6003 Grand Forks. ND 58202-7118

7(11-777-2198

James A. Clum

State Univcrsity of NY - Binghanaton Wayne L. Elban

Mechanical Engineering Department Loyola College

Vestal Park East Dept. of Electrical Engineering

Binghamton, NY 13902-6000 and Engineering Science

4501 N. Charlcs Street

Kristen P. Constant Baltimorc. MD 21210

Iowa State University 410-617-2853

3053 Gihnan

Ames. IA 50011 Leonard W. Fine

515-294-3337 Department of ChemistD'

Columbia University in the City

Paul J. Coyne. Jr. of New York

Dcpt of Electrical Engineering Havemeycr Hall. Box 758

and Engineering Science New York. NY 10(127

Loyola College 212-854-2017

4501 North Charles St.

Baltimore. MD 21210-2699 Richard Fields

41(1-617-2512 NIST

Paul Cummings Donnctta Fisher

Newport News Public Schools Norfolk State University

Jai N. Dahiya Paul Fleitz

Southeast Missouri Statc University WL/MLPS. Bldg. 651

Mail Stop 6600 One University Plaza Wright-Patterson Air Force Base

Cape Girardeau. MO 63701-4799 3005 P Street. Ste. I

314-651-2390 Dayton. OH 45433

513-255-6771. ext. 3180

JoDee Daufcnbach

Lone Peak Engineering

12660 S. Fort Street (950 E.) Suite Y

Draper. UT 84020-9362

801-533-1732

o,o

XXVIII
Kathrvn Forloaad Thomas Gomlan

GMI Engineering mid Management Department of Forest Products

Institute University of Idaho

1700 W. Third Avenue Moscow. ID 83844-1132

Flint, MI 485(}4 2(}8-885-7402

81[I-762-981!

Kopl Halperin

Michael Forrest Department of Mechanical Engineering

Norfolk Public Schools School of Engineering and Engineering

Technology

Shatac Foster Penn State at Eric

Norfolk State University Eric, PA 16563

814-898-6347

Anna C. Frakcr

National Institute of Standards Carol Handwcrkcr

and Tcchnology NIST

Materials Bldg. Room B226

Gaithersburg, MD 20899 Robert Harvey

3(}1-975-6(1(19 Norfolk State University

Ted Gabrykcwicz Janellc Haynes

Engineering Technologies and Norfolk State University

Science Department

Hocking College Kristian Helmcrson

3301 Hocking Parkway NIST

Nclsonvillc, OH 45764

614-753-3591. ext. 2403 George W. Henderson

Virginia State University

Smnucl C. Gambrell, Jr. Petersburg. VA 23806

University of Alabama 804-524-5913

Dcpartmcnt of Engineering Science

and Mechanics Vernon S. Hillsman

Tuscaloosa. AL 35487 Purdue University

205-348-1615 1417 Knoy Hall, MET Dept.

Wcst Lafayette, IN 47907

James E. Gardner 317-494-7486

Tcchnical Staff Assistant

NASA-Langley Research Center J. Cecil Holt

Building 1219, Room 216 Dozier Middle School

MS 118 Nc\vport News Public Schools

Hampton. VA 23665-0001

804-864-6003 Charles R. Horton

Norfolk State Univcrsity

Michael Gatling

Norfolk State University Ronncll E. Howard. Jr.

2401 Corprew Avenue Norfolk State University

Norfolk, VA 23504

804-683-8655 Donald Htmston

NIST

Laurie George

American Dental Association

xxix
Willie L. Hunter AlmaK. Karplus

Norfolk State University Department of Mechanical Engineering

2401 Corprew Avenue Western New England College

Norfolk, VA 23504 1215 Wilbmhanl Road

Springfield. MA 01119-2684

Ben Hutchinson 413-782-1220 or 1273

Chemistry Dcpartmcnt

Pepperdine University Kris Kern

24255 Pacific Coast Highway Norfolk State University

Malibu, CA 90263 2401 Corprew Avenue

310-456-4321 Norfolk. VA 23504

804-683-2447

John lppolito

Norfolk University Richard Kerchner

2401 Corprew Avenue Oak Ridge National Laboratory

Norfolk. VA 23504 P.O. Box 2008

Oak Ridge. TN 37831

John E. Jablonski 615-574-6270

Fulton-Montgomery Community College

2805 St. Highway 67 Khalid H. Khan

Johnstown, NY 12095 University of Portland

518-762-465 I, ext.321 5000 N. Willamette Blvd.

Portland, OR 97203-5798

James A. Jacob 503-283-7276

Norfolk State University

2401 Corprcw Avenue Mushtaq Khan

Norfolk, VA 23504 Norfolk State University

804-683-8109 2401 Corprc\,_Ave.

Norfolk, VA 23504

Thomas J. Jenkins

Department of the Air Force Thomas F. Kilduff

AFIT/ENG 504 Brafferton Cirle

2950 P Street Hampton, VA 23663

Wright Patterson Air Force Base 804-851-0272

OH 45433-7765

513-255-5581 Glenn S. Kohnc

Associate Professor of Electrical

Rodney Jiggetts Engineering & Engineering Science

NIST Loyola College

DS-224

Scan Joyner 4501 North Charles Street

Norfolk State University Baltimore, MD 21210-2699

410-617-2249

Michael A. Kamitz

Oak Ridge National Laboratories Richard P. Krcpski

P. O. Box 2008 lnterMet Technology

Bldg. 4515, MS 6065 1306 Airport Road

Oak Ridge, TN 37831-6065 Aliquippa, PA 15001

615-574-5150 412-378-3781

XXX
Dimm P. LaClairc JzunesV. Masi

Norfolk State University Wcstcm New England College

2401 Corprc\v Avcnuc Department of Electrical Engineering

Norfolk. VA 23504 Box 2168

804-683-9072 Springficld, MA 01 !19

413-782-1344

Wanda Lassiter

Norfolk State University H. Thomas McClclland

2103 14thAvenue E.

Lei Lin Mcnomonie, WI 54751

Norfolk State University 715-232-9597

2401 Corprcw Avenue

Norfolk. VA 23504 Joseph L. McDuffie

Norfolk State University

Stephen F. Lin

North Carolina Central University Alfred E. McKcnney

3! !6 AnnoaadaleRoad Consultant

Durham, NC 27705 516 Fairfax Way

919-560-6463 Williamsburg, VA 23185

804-221-0476

Craig L. Little

Norfolk State University Evelyn D. McKenney

Consultant

Ping Liu 516 Fairfax Way

Eastern Illinois University Williamsburg, VA 23185

101 Klchm Hall 804-221-0476

Charleston. 1L 61920

217-581-6267 Jon McKcnncv

Electrical Contractor

William G. Long United Kingdom

Babcock & Wilcox Co.

Lynchburg Research Ccnter Joscph E. Moore

P.O. Box 11165, Mt. Anthos Road Norfolk State University

Lynchburg, VA 24506-1165 2401 Corprew Avenue

804-522-5716 Norfolk, VA 23504

804-683-8081

Denver Lovett

NIST Thcron Moorc

Norfolk State Univcrsity

Thomas Lucatorto

NIST James P. Nag3',Jr.

Eric ComnaunityCollcgc

Donald H. Martin 4580 Lake Shore Road

Tri-State University Hamburg, NY 14075

300 S. Darling Street 716-627-3930

Auburn, IN 46703-0307

Work 219-665-4265 Dale Newbury

NIST

xxxi
Patricia J. Olesak Scott Richlcn

MET Department U.S. Department of Encrgy-HQ

Purdue University

1417 Knoy Hall, Room 115 Curt A. Richter

West Lafayette. IN 47907 NIST

317-494-7532

Stephen D. Ridder

Joseph Pedulla NIST

NIST

Joseph Rittcr

Allen Pierce NIST

Technology Department

Elizabeth City State University James R. Roberts

Cmnpus Box 844 NIST

Elizabeth City, NC 27909

919-335-3440 Harry L. Rook

NIST

Twana Pilgrim

Norfolk State University William A. Ross

Muskegon Community College

Steven Piippo 221 Quarterline Road

Richland High School Muskegon, MI 49442

930 Long Avenue 616-777-0367

Richland, WA 99352

509-946-5121 Paul Russell

Ocean Lakes High School

Henry Prask Virginia Beach Public Schools

NIST

Prcston St. John

Liya L. Regcl Norfolk State University

Clarkson University

Box 5700 RobertJ. Scheer

Potsdam. NY 13699-5700 Protein Solutions. inc.

315-268-7672 350 W. 800 North Suite 218

Salt Lake City. UT 84103

Kenneth L. Reifsnider 801-596-2675

Virginia Polytechnic Institute

and State University Kurt C. Schultz

Virginia Institute of Materials Tumbo Universit\'

Systems School of Engineering

120 Patton Hall Box 3030

Blacksburg, VA 24061-0219 Gumbo, Puerto Rico 00778

703-231-5316

Lvle H. Schwartz

Hassan M. Rcjali National Institute of Standards

Cai Poly, Pomona and Technology

38(11W. Temple Street B-309, Building 223

Pomona, CA 91268 Gaithersburg, MD 20899

909-869-2586 30 !-975-5658

xxxii
Garland Scott Charter D. Stincspring !1

Cal Poly-Pomona West Virginia University

3801 W. Temple Avenue Chcmieal Engineering

Bldg. 9, Room 227 Morgantown, WV 26506-6102

Pomona, CA 91768 304-293-2111

Guna Sclvaduray Rob Stovcr

San Jose State University Ocean Lakes High School

Department of Materials Engineering Virginia Beach Public Schools

San Jose, CA 95192-0086

408-924-3874 Amaand Taylor

Virginia Beach Public Schools

Robert D. Shull

National Institute of Standards Waheed Uddin

and Technology University of Mississippi

B-140, Materials Department of Civil Engineering

Gaithersburg, MD 20900 University, MS 38677

301-975-6035 601-232-5363

Kantis Simmons Robert Uhl

Norfolk State University Director of New Services Development

ASM International

K. George Skena St. Rt. 81

Norfolk Technical Vocational Center Materials Park, OH 44073

1300 N. Military.Highway 216-338-5151

Norfolk, VA 235(12

804-44 i-5633 Mehmet Uz

Lafayette College

Tom Spencer 341 AHE, Chemical Engineering Dept.

Chesapeake Public Schools Easton, PA 18042

610-250-5408

F. Xavier Spiegel

Engineering Department Tommy Lee Waskom

Loyola College Eastern Illinois University

4501 N. Charles Street 101 Klehm Hall

Baltimore, MD 21210-2699 Charleston, IL 61920

410-617-2515 217-581-6267

Charles Stenger Richard Watts

Norfolk State University NIST

David Stienstra Maurice Webber

Asst. Prof. of Mechanical Engineering Norfolk State University

Rose-Hulman Institute of Technology

5500 Wabash Ave. Bernard J. Weigman

Terre Haute, IN 47803 Professor of Physics and Engineering

812-877-1959 Loyola College in Maryland

4501 North Charles St.

Baltimore, MD 21210-2699

410-617-2000

XXXlll
David E. Werstlcr

Wcstcm Washington University

Dcpartmcnt of Engineering Tccimoiogy

Bcllimgham. WA 98225-9(186

206-650-3447

Harvey A. West

Department of Materials Science &

Engineering

North Carolina State Univcrsity

P.O. Box 7907

Raleigh, NC 27695-7907

9 !9-515-3568

Jerry L. Wickman, Director

Plastics Research and Education Center

Ball State University

College of Applied Sciences and Technology

Department of Industry and Technology

Muncic, IN 47306-0255

3 i7-285-5648

Edward L. Widener

MET Department

Purdue University

l_loy Hall - Room !19

West Lafayette, IN 47907

317-494-7521

William R. Wilcox

Clarkson University

Box 5700

Postdam. NY 13699-5700

3 !5-268-6466

Johnnie Wright

Norfolk State University

Debbie Yamell

Prentice Hall

113 Sylvan Avenue

Englcwood Cliffs. NJ 07632

201-592-2066

Michael Zachariah

NIST

xxxiv
XXXV
NATIONAL EDUCATORS' WORKSHOP

Update 94: Standard Experiments

in Engineering Materials Science

and Technology

c.v_ __h_..'3_.,- _.Q

(b) (c)

Sponsored by

National institute o[ Standaxds and National Aeronautics & Space Norfolk Slate University United States

& Technology, Maleriais Science Administration Schools ot Technology & Department ot Energy

& Engineering Laboratories Langley Research Cenler Science FMPC and ORNL

with the support of American Society for Engineering Education

ASM international

American Society for Testing & Materials

Battelle, Pacific Northwest [,aboratary

Fernald Environmental Resloralion Management Corp.

Marlin Marietta Energy Systems, Inc.

Materials Education Council

xxxvi
xxxvii
Recognizing Contributions

o**

XXXVIII
Recognizing Contributions

Registration

xxxix

TECHNOLOGY TRANSFER OF NIST RESEARCH

Lyle H. Schwartz

National Institute of Standards and Technology

B-309, Building 223

Gaithersburg, Maryland 20899

Telephone 301-975-5658

1

Historical Perspectives 

Lessons from Abroad 

Congressional Actions 

Experiences at N IST 
HISTORICAL PERSPECTIVES 

World Leadership Through the 1960s 

Declining Market Share in 1970s 

Government Roles in Civilian Technology 

Developed in 1980s 

Congressional Leadership 
LESSONS FROM ABROAD 

Technology Development; 

Industry Led, Government Lab Supported 

Technology Deployment; 

Small Business Focus in Japan and Europe 
CONGRESSIONAL ACTIONS 

1980 - Stevenson-Wydler 

1984 - Joint R&D Partnerships 

1986 - GoGo Labs Given CRADA Authority 

1987 - Malcolm Baldrige Quality Award Initiated 

1 988 - Technololgy Competitiveness Act 

Creates NIST, ATP, MTC 

1992 - Technology Reinvestment Program 

1993 - S.4, H.R. 820 Pending 
PRESIDENTIAL ACTION 

1993 - President Clinton targets DOC and NlST 

for major role in assisting industry, calls 

for significant budget growth. 
WHAT DOES NlST DO? 

Fundamental Research 

Develop New Measurement Techniques and Devices 

Characterize Materials , Products, and Systems 

Evaluate and Publish Standard Reference Data 

Provide Standard Reference Materials 

Provide Measurement Assurance Services 

Develop and Propose Product Standards and Code Provisions 

Award Grants to U.S. Industry for Pre-Competitive Technology 

Demonstrate the Results 

- Translate and Transfer to Users 

- Manufacturing Technology Centers 

Manage the Malcolm Baldrige National Quality Award 
NIST DIRECT APPROPRIATIONS 

President's Plan 

FY 1997 Proposal 

FY 1995 Actual 

~anufacturing 

Extension 

Partnership 

$1 18M 

Construction 

of Research 

Facilities 

$64.7M 

Quality 

$3.4M 

Manufacturing 

Extension 

Partnership 

$90.6M 

\O Total Appropriations = $854.7M Total Appropriations = $1,379M 
EXPERIENCES AT NIST 

Advanced Technology Program 

Manufacturing Extension Partnership 

NIST Laboratory Program 
ATP CHARACTERISTICS 

Unique Mission Focus - High-Risk Enabling Technology 

Development to Stimulate U.S. Economic Growth 

Partnership with lndustry - lndustry Conceives and 

Proposes Ideas, Executes and Cost-Shares Projects; 

ATP Applies Selection Criteria 

Focused and General Competitions - for Depth and 

Breadth 

Competitive Selection Process - Technical and 

Business Reviews 

Sunset Provisions - for Both Programs and Projects 

Performance Metrics - for Both Process and Programs 
ADVANCED TECHNOLOGY PROGRAM 

Focused Program Areas 

First Round: April, 1994 

Manufacturing for Composites 

Computer Integrated Manufacturing for Electronics 

Health Care Information Infrastructure 

DNA Diagnostic Tools 

Component Level Software 
MANUFACTURING EXTENSION PARTNERSHIP 

NlST is building the partnership on four major elements: 

Manufacturing Technology Centers (MTCs) 

Manufacturing Outreach Centers (MOCs) 

the State Technology Extension Program (STEP) 

LINKS - a support, coordination and linking1 

networking infrastructure 
NIST MANUFACTURING EXTENSION PARTNERSHIP 

(Including MTCs, STEP Awards, and TRP Projects Managed by NIST) 

0 Existing MTC 

@ MTC Recipient of TRP Award 

A TRP Award 

STEP Award 
NIST AND THE TECHNOLOGY 

Participation in Evaluation 

TRP and the MEP 
MATERIALS SCIENCE AND ENGINEERING 

LABORATORY 

MSEL 
MSEL MISSION 

Stimulate the more effective production and 

use of materials by working with industry in the 

development of technology, measurements, 

and standards. 
MSEL OBJECTIVES 

Foster the Use of Advanced Materials in 

Commercial Products 

Foster the Development and Implementation of 

Technologies for Advanced Processing of 

Materials 

Support the Measurement Base and Standards 

for Materials Science to Serve the Needs of 

U.S. Industry 
HOW WE ARE ORGANIZED 

By Discipline 

- Ceramics 

- Materials Reliability 

- Metallurgy 

- Polymers 

- Reactor Radiation 

Program Office to Manage 

Cross-Divisional Programs 
MSEL AREAS OF PREEMINENT 

COMPETENCES 

Processing 

- Metals Solidification 

- Polymer Blends and Composites 

- Process Sensing 

Phase Equilibria 

Mechanical Behavior of Brittle Materials 

Materials Characterization 

- Non-Contact Sensing 

- Ceramic Powder Characterization 

Materials Data 

Neutron Measurement Methods 
MSEL-CUSTOMER INTERACTIONS 

MSEL 

Standard Reference 

Materials 
WHAT WE DON'T DO 

Design Programs for Materials Development 

- Serendipity is followed only with industrial 

partners 

- The exception to the rule - Dental 

Materials 

FACILITY USE 

Non-NIST 

W Other NlST 

I 
USERS BY D 

Engineering 

9% 

Chemis 

26% 

try 

Other Physics 

10% 

TOTAL USERS = 921 for FY93 
MATERIALS SCIENCE AND ENGINEERING LABORATORY 

PROGRAMS ON TECHNOLOGY DEVELOPMENT 

CRADAs 

Examples: Welding 

Polymer Composites 

Metal Casting 
27

ACC FOCAL PROJECT 

CONSORTIA WITH INDUSTRY: 

COLLABORATION FOR COMMERCIAL SUCCESS 

Polymer Blends 

Ceramic Machining 

Casting of Aerospace Alloys 
NIST/INDUSTRY CONSORTIUM 

ON POLYMER BLENDShLLOYS 

ORIGINS: 

PERIOD OF 

OPERATION: 

Planning Workshops on 

April 207 1992 at NlST 

* February 1993 to February 1997 

MEMBERSHIP: Armstrong World Industry 

(April 1994) Aristech Chemical Corp. 

Goodyear Tire and Rubber Corp. 

Raychem Co. 

Rohm & Haas 

Sandia National Lab. 

3M Co. 
ON POLYMER BLENDSIALLOYS 

GOALS: To Improve the New-Product 

Development Cycle 

To lmprove the Process Design 

of Polymer Blends/Alloys 

APPROACH: Thermodynamics and Kinetics of Phase Behavior 

Compatibilization and Interfacial Modification 

* On-Line Structure Characterizatior; Instrumentation 

and Technique for MixingIExtrusion 

Sensor Development 
NIST CERAMIC MACHINING 

CONSORTIUM 

Industry/GovernmentlUniversities 

MISSION: Assist U.S. industry, through a joint research 

program, in the development of precision 

machining technology for the manufacture of 

reliable and cost-effective products made from 

advanced ceramics. 

GOALS: Provide measurement methods, data, and 

mechanistic information needed by industry for the 

development of innovative methods for machining 

of advanced ceramics. 

MEMBERS: Members provide funds, materials, services in-kind, 

technical advice, and guidance. 
NIST CERAMIC MACHINING 

CONSORTIUM MEMBERS 

Ceradyne, Inc. 

Cincinnati Milacron, Inc. 

Corning, Inc. 

Dow Chemical Company 

Eaton Corporation 

Eonic, Inc. 

Ford Motor Company 

General Electric Company 

General Motors Corporation 

Norton Company 

SAC International 

Stevens Institute of Technology 

Texas A&M University 

Torrington Company 

West Advanced Ceramics 

Tower Oil and Technology 

University of Maryland 

University of Rochester 

W. R. Grace & Company 
36
37

BULK ETCHING OF SILICON FOR

MICROMACHINING

and

MICROMACHINING OF SUSPENDED

STRUCTURES IN SILICON

John H. Comtois

Thomas J. Jenkins

and

Victor M. Bright

Department of Electrical and ComputerEngineering

Air Force Institute of Technology

Wright-Patterson Air Force Base

Ohio 45433-7765

Telephone 513-255-3636 ext. 4598

39
40
Bulk Etching of Silicon for Micromachining

Thomas J. Jenkins, Capt, USAF

John H. Comtois, Capt, USAF

Victor M. Bright, PhD

Department of Electrical and Computer Engineering

Air Force Institute of Technology

Wright-Patterson Air Force Base, OH 45433-7765

KEY WORDS: anisotropic etching, microelectromechanical systems (MEMS),

micromachining.

PREREQUISITE KNOWLEDGE: The students should be familiar with

conventional integrated circuit fabrication. This experiment can be incorporated into an

introductory course on solid state sensors. If the students perform the etch, they should

have completed a previous laboratory session involving hazardous chemical handling.

OBJECTIVES: This experiment introduces students to the fabrication of

microelectromechanical systems (MEMS) and prepares students to conduct more

complex experiments in micromachining. The students perform a laboratory experiment

to determine the characteristics of anisotropic silicon etching. In particular, students gain

experience with anisotropic etches which are peculiar to micromachining, in contrast to

their previous experience with isotropic etches used in microelectronic fabrication. After

completing this experiment the students will be able to estimate the anisotropic etch rate

of different crystal planes of bulk silicon and the resultant etched profiles.

EQUIPMENT AND SUPPLIES: This experiment uses routine equipment

found in microelectronic and chemistry laboratories. However if a reflux reactor is not

available, it can be purchased or assembled from standard laboratory plastic containers.

An example of a handmade reflux reactor is illustrated in Figure 1.

The supplies consist of special etching solutions and silicon substrates lbr etching.

Ethylenediamine, water, and pyrocatechol (EDP) or potassium hydroxide (K()H) is the

required etching solution. The students will etch either a test die or a patterned wafer

41
provided by the instructor. The recommended test die consists of a collection of masked

features fabricated through the MOS Implementation Service (MOSIS). A suggested

layout and the specific MOSIS criteria are described in the Instructor Notes. If M()SIS is

not available, a patterned silicon wafer can be used. The wafer specifications arc in the

Instructor Notes.

PROCEDURE: The experiment is conducted in a sequence of steps. These

steps require the students to predict the etch results, prepare the etching solutions,

perform an etch, and analyze the results. Also, students should be properly briefed

concerning the hazards of the various etching solutions. Adequate protection, such as

goggles, gloves, and aprons, as well as proper ventilation, must be used. The etching

solutions are extremely corrosive and toxic.

Prediction: The students begin by predicting the resultant etch for each of the

open shapes. The predictions consist of: profile, etch time, and final etch depth. The

layout, its crystallographic orientation, and etching conditions are provided to the

students to enable the calculations.

Etching solution preparation: The students prepare the selected etching

solutions. EDP and KOH are the preferred anisotropic etching solutions. A buffered

solution of hydrofluoric (HF) acid must also be prepared. Since silicon surfaces will

readily form a thin native oxide whenever exposed to room air, the HF is required to strip

any native oxide which forms in the regions to be anisotropically etched.

The EDP should be purchased ah'eady mixed. However, the KOH will need to be

mixed. A solution of 44 grams of KOH crystals in 100 ml of deionized (DI) water will

produce reliable results. The HF should be mixed in a 5% solution with DI water.

Etching: Before the test die are etched, the die must be dipped in the HF solution

for 10 seconds and then thoroughly rinsed in DI water. After rinsing, the die are

immediately placed in the etch apparatus and dipped in the anisotropic etching solution.

The die must be handled with Teflon or other types of plastic tweezers. The etching

solutions will corrode metal parts. For proper results, the EDP and the K()H mr,st bc

maintained near 95"C and 85°C, respectively. While etching, both etching solutions must

be gently stirred.

After etching the die are removed from the etch apparatus, and thoroughly rinsed

in DI water. The etch time should be recorded to determine the etch rate during analysis.

42
The die are then dried by removing the excess water with a lint-free tissue and left to dry

in the air. Also, the die can be placed in an oven for a few minutes at 100"C.

Examination and Analysis: The students examine the test die to determine the

characteristics of the etched pits. The test die can be examined with an optical

microscope to determine the etch depth and profile. If a profilometer is available, the

students can use this instrument to measure the profile, as well. The students should

correlate the pit characteristics with the lateral dimensions and crystallographic

orientation of the masked regions used to pattern the pits. Significant deviations from

their predicted results should be explained as part of the laboratory report.

SAMPLE DATA SHEETS: Self-Evident.

INSTRUCTOR NOTES: An introduction to the emerging field of MEMS and

micromachining should combine hands-on laboratory experiments with class room

lectures. The experiment described in this paper complements a discussion of bulk

silicon micromachining as it applies to fabrication of MEMS. A CMOS-compatible

process may be used tbr this purpose.

Suggested Lecture Materials: To obtain the most benefit from this experiment,

the prerequisite knowledge in microelectronics should be supplemented with an

associated lecture covering the following topics: motivation for MEMS, silicon crystal

structure, the properties of anisotropic etching, the influence of crystal orientation with

respect to the device geometry, and the electronic materials compatibility issues.

Micromachining is a developing field which promises to reduce device size and

weight in many applications [1], [2]. Micromachining has already moved into

commercial production in the area of accelerometers. For example, substantial markets

are developing as micromachined accelerometers are incorporated in automotive air bag

systems. Since micromachining is closely related to microelectronic fabrication

techniques, it makes sense to introduce the topic in microelectronic courses. The ability

to incorporate micromechanical structures with integrated circuits enables the

development of improved sensors and other instrumentation.

MEMS can be fabricated using many difl_rent processes. One such process is

bulk silicon anisotropic etching. This process uses the unique crystallographic propcrtics

of silicon to form cavities and suspended structures. These mechanical features are

fabricated in the same bulk material which is used to fabricate integrated circuit,s. For

43
example, conventional CMOS processing can be combined with bulk silicon

micromachining [3].

Miller indices are used to define crystal planes. The Miller indices and standard

orientations in silicon wafers are illustrated in Figure 2. Figure 3 should be photocopied

onto heavy paper, cut-out, and then folded to produce a 14-sidedmodel of a silicon

crystal. This model can be used to illustrate the crystal planes.

In silicon, the atoms are spaced more closely in some crystal directions than

others. In particular, the <111> direction has the least space between atoms, while the

<100> direction has the most space between atoms. Some chemicals etch along these

crystal directions at different rates, so such etching solutions are called anisotropic. Fo,"

example, EDP will etch in the <100> direction 35 times faster than in the <1 ! 1>direction

at 115"C,while tbr KOH the ratio can be 400:1 at 85"C lbr those same directions 141.

This selectivity permits the use of the {I 11}planes as etch stops when etching silicon

waters whose faces are {100} oriented. Figure 4 shows how wafers are given a flat to

indicate the orientation of the various crystal planes. Standard CMOS circuits,arc

fabricated using {100} wafers, so an anisotropic etch will result in the profile shown in

Figure 5. This figure also compares the anisotropic etch with the isotropic etch normally

used in microelectronic circuit fabrication.

By defining a rectangular mask opening aligned to the {110}-oriented wafer flat,

a pit can be etched into the wafer. The etch proceeds in all directions, but fastest in the

<100> direction. At the edges of the pit, where {111}planes intersect the sides of the

mask opening, the etching solution cannot get to a faster etching surfacc, so those planes

are gradually exposed as the etch proceeds. The etch virtually stops whc,at_nlythose lbur

{111} planes are left exposed, which leaves a pyramidal pit in the wafer. Since there is

some slow etching in the <111> direction, there will be a Slight undercutting of the mask

edges. To reduce this undercutting, a heavy p-type diffusion can be placed around the

mask opening which further slows down the etch process [31.

Reflux Reactor and Other Supplies: The reflux reactor, which isshown in

Figure 1, was fabricated from a plastic beaker (250-ml) with a plastic cover. A slightly

smaller beaker was placed inside to suspend a two-inch lluorowarc wafer holder. The

bottom of the smaller beaker was perforated with four 3/4-inch holes. Also, the water

holder was perforated with several dozen small holes which are large enough to permit

the free flowing of the etching solution, but small enough to prevent the test die from

falling through the basket. This smaller beaker should rest inside the larger beaker with

enough space so as not to impede the stir bar action. The cover has a small access hole in

44
the center to allow the insertion of a thermometer tube. This reactor was fabricated with

plastic parts, but glass is also acceptable. Metal components are not recommended.

The test die should contain some adaptation of the features depicted in Figure 6,

which is a simple etch gauge. The gauge was fabricated through MOSIS. If the design is

submitted to MOSIS, the Orbit SCNA_MEMS or SCPE_MEMS process must be used

[3]. The suggested features consist of square and rectangular patterns of various

dimensions. This collection of patterns will permit the students to observe the effects of

various dimensions on the etch time and pit profile. Also, the students will be able to

observe the differences between KOH and EDP etching solutions.

If the test die can not be obtained through MOSIS, a suitable alternative can be

fabricated in a microelectronics laboratory. The initial silicon wafer should be {1(10}-

oriented. The patterns to be etched should be masked with silicon dioxide. No specific

oxidation schedule needs to be followed; however, the oxide should be pin-hole free and

at least 210-nm thick [5]. The dimensions of the patterned features should range from 2(I

to 100 micrometers. Using these feature sizes, the students will be able to make adequate

observations to determine the etch rates. An example wafer processing technique can be

found in [6].

Anticipated Results: The etch should be judiciously timed so that some features

are completely etched while others are not. This will allow estimates of etch rate based

upon the size of the largest completely etched pit. Also, an incomple,,qy etched pit can

be measured to determine the etch depth, and thus, the etch rate. Students should use the

method shown in Figure 7 to calculate the etch depth. The students should correctly

observe that the etch rate is the same for all features; however, the final depth of the

etched pit is determined by the length of the shortest side of the rectangular feature. The

etch process is a self-terminating process which is determined by the geometry of the

layout. Hence, the students should realize the utility of anisotropic etching solutions in

the fabrication of MEMS.

Upon conclusion of the experiment, the students should observe the various states

of completion of the etched pits as the dimensions of the masked features vary. An

example of etch results using EDP is shown in Figure 8. The etch duration was 3(I

minutes, and the etch rate was about 0.54 micrometers pet"minute in the <1(10> direction.

The smallest completely etched pit was 23x23 micrometers. Figure 9 depicts an example

of etch results using KOH alter 2.5 minutes of etching. For this case, the smallest

completely et_chedpit was 19x19 micrometers, and the etch rate was 5.4 micrometers per

minute.

45
Suggested Follow-on Experiments: The knowledge gained in this experiment

will prepare the students for the subsequent experiment where they will fabricate

suspended structures.

SOURCES OF SUPPLY: The routine chemical supplies and K()H arc available

from Sigma Chemical Corp., P.O. Box 145(}8,St. Louis, MO 63178. The EDP can bc

purchased already mixed from Transene Co., Inc., US Rt. 1,Rowlcy, MA {11969.

REFERENCES:

1. J.Bryzek,K.Petersen,and W.McCulley,"Micromachincson the march,"/. E.

E. E. Spectrum,pp. 20-31,May 1994.

2. G. Stix, "Micron machinations," Scientific American, pp. 1{}7-117,Nov 1992.

3. J. Marshall, M. Gaitan, M. Zaghloul, D. Novotny, V. Tryee, J-l. Pi,C. Pifi,,iand ,

W. Hanstbrd, "Realizing suspended structure on chips fabricated byCMOS

foundry processes through the MOSIS service," NISTIR 5402, U. S. Department

of Commerce, National Institute of Standards and Technology, June 1994.

4. K.E. Petersen, "Silicon as a mechanical material," Proc. I. E. E. E., vt_l.7{1,pp.

420-457, May 1982.

5. L.Ristic, ed., Sensor Technology and Devices, Artech House, Norwood, MA,

1994.

6. T. Jenkins and E. Kolesar, "Laboratory experiments in integrated circuit

fabrication," NASA Conference Publication 3201, National Educators'

Workshop: Update 1992, Standard Experiments in Engineering Materials

Science anti Technology, National Aeronautics and Space Administration Office

of Management, Scientific and Technical Information Program, pp. 235-270,

1993.

7. S.M. Sze, Semiconductor Devices - Physics anti Technology, John Wiley &

Sons, New York, 1985.

46
Thermometer

Tight Lid

! ! " - i ..............

Larger Beaker

Smaller Beaker

Water Bath

Water Level

EDP level

Figure 1. Diagram of lab-built reflux reactor.

zl z z

•'__

xF xf

(100) (I I0) (111

Figure 2. Miller indices of some important planes ill cubic crystals [71.

47
<110>

<110>

Cut

<100> _ Slots

Figure 3. Fourteen-sided crystal model cutout.

48
{111} n-type {111} p-type

i Primary FP_t{lrYo}

_ Flat {110}

\ S condary

Flat {100}

{100} n-type {100} p-type

Primary Primary

Flat {110} Flat {110}

Figure 4. Identifying flats of a silicon wafer [after 7].

Oxide Mask

(b)

(a) (c)

Figure 5. Illustration of differences between isotropic and anisotropic etch of { 1()()}

silicon wafer with similar masks. (a) Mask alignment parallel to the primary wafer llat.

(b) Profile of isotl'opic etch. (c) Profile of anisotropic etch showing crystal plane

directions.

49
60 50 40 30 2()x 15 _tm

20 _m T

Figure 6. Suggested layout for test die. The minimum spacing between boxes is 20 _4m.

Oxide Mask

< 111> 54.74"

< I0()>

d

d = x tan ( 54.74" ) Si Substratc

Figure 7. Profile of an incompletely etched pit for a masked {1()()}surface orientation.

$0
Figure 8. An example of etch results using EDP t'ov3() minutes. The largest c_)mpletely

etched pit is 23x23 _am.

Figure 9. An example _1 etch results using K()H tov 2.5 minutes. The lal,-c_,t ,._mpletci 5

etched pit is 19x19 .urn.

51

Micromachining of Suspended Structures ill Silicon

John H. Comtois, Capt, USAF

Thomas J. Jenkins, Capt, USAF

Victor M. Bright, PhD

Department of Elecu'ical and Computer Engineering

Air Force Institute of Technology

Wright-Patterson Air Force Base, OH 45433-7765

KEY WORDS: anisotropic etching, microelectromechanical systems (MEMS),

micromachining.

PREREQUISITE KNOWLEDGE: The students should previously complete

the anisotropic etch study, "Bulk Etching of Silicon for Micromaehining," [1] and be

familiar with conventional integrated circuit fitbrication technologies. This experiment

can be incorporated into an introductory course on microelectronic devices and their

fabrication.

OBJECTIVES: This experiment introduces students to the fabrication of

microelectromechanical systems (MEMS) and prepares students to conduct more

complex experiments in micromachining. The students perform a laboratory experiment

to fabricate suspended structures in silicon, such as cantilevers and trampolines. After

completing this experiment the students will be able to predict the shapes of suspended

structures created with bulk silicon etch processes.

EQUIPMENT AND SUPPLIES: This experiment uses routine equipment

found in microelectronic and chemistry laboratories. If a reflux reactor is not available, it

can be purchased or assembled from standard laboratory plastic containers. An example

of a handmade reflux reactor is illustrated in Figure 1, and it is described in [1].

The supplies consist of special etching solutions and silicon substrates for etching.

Ethylenediamine, water, and pyrocatechol (EDP) or potassium hydroxide (KOH) can be

used as the etching solution in this experiment. KOH is acceptable for this experiment

and is a cheaper and faster etching solution than EDP, but it is not compatible with

53
complementary metal oxide semiconductor (CMOS) fabrication. The students will etch

either a test die or a patterned wafer provided by the instructor. The recommended test

die consists of a collection of masked features fabricated through the MOS

Implementation Service (MOSIS). A suggested layout and the specific MOSIS

fabrication criteria are described in the Instructor Notes. If MOSIS is not available, a

patterned silicon wafer can be used. The wafer specifications are in the Instructor Notes.

PROCEDURE: The students conduct the experiment in the following sequence:

1) predict the final shapes of the suspended structures and the etch times, 2) etch the test

die, stopping periodically if time permits to check on the progress of the etch, and 3)

examine the etched structures, compare them with the predicted shapes and etch times,

and comment on the differences. The students should be properly briefed concerning the

hazards of various chemicals used in the experiment.

1) Prediction: The students begin by predicting the shape that will result from

the anisotropic etch of each test pattern. The test pattern mask layouts, their

crystallographic orientation, and the etching conditions are provided to the students. This

information will also enable the students to predict a minimum etch time required to fully

release the structures. The etch time needed to form completed pits beneath the

suspended structures is based on the time th,'ttwould be needed to etch an open pit of the

same outside dimensions. The students should use the results of the prerequisite

experiment [1] to determine the etch rates they can expect for this experiment. In order to

visualize the final shapes, the students must also predict how the etch pits will form from

start to finish.

2) Etching: The students prepare the selected etching solutions as described in

[1]. After preparing the etching solution, the students etch their test die. The students

should stop periodically to observe the progress of the etch. This etch procedure varies

from the one described in [1], because the surface tension must be considered to properly

release the suspended structures. Specific procedures and the suggested etch intervals are

given in the Instructor Notes. Adequate protection such as goggles, gloves, aprons and

proper ventilation must be used. The etching solutions are extremely corrosive and toxic.

3) Examination and Analysis: Each time the etch is stopped, the students

examine the test die under a microscope to determine the shapes of the etched pits and

suspended structures. The students compare these intermediate results with their

54
predictions of both the etch progress and the required etch time. At the completion of the

etch the students compare tile final shapes with their pledictions. Any deviations from

the predicted results should be explained as part of the laboratory report.

INSTRUCTOR NOTES: Tile experiment described in this paper complements a

discussion of bulk silicon micronlachining as it applies to fabrication of MEMS. Since

micromachining is closely related to microelectronic fabrication techniques, it makes

sense to introduce the topic in microelectronic courses. This experiment presents a

hands-on laboratory experience which, when combined with classroom lectures, provides

an informative and exciting introduction to the emerging field of MEMS and

micromachining.

Suggested Lecture Materials: To obtain the most benefitfrom this experiment,

the prerequisite knowledge in microelectronics should be supplemented with an

associated lecture on the motivation for MEMS, especially applications of suspended

structures in sensors and actuators.

Micromachining is a developing field which promises to reduce the size and

weight of many different types of sensors and actuators 12]-[4]. It also promises to open

up new fields of application in such diverse areas as medical systems and space

exploration. The ability to incorporate micromechanical structures with integrated

circuits enables the development of improved sensors and other instrumentation.

Micromachining has already moved into commercial production of pressure transducers

and accelerometers. For example, substantial markets are developing as automobile

manufacturers replace bulkier and less controllable automotive air bag crash sensors with

micromachined accelerometers [211.

Bulk silicon micromachining plays a key role in the design of solid-state sensors.

The advent of a standard process for creating CMOS-compatible MEMS structures [5]

allows researchers who do not have access to an in-house fabrication facility to fabricate

and to take advantage of suspended structures [6], [711.Two of the most desirable

properties of suspended structures are thermal and electrical isolation from the substrate.

Thermal isolation allows a resistively heated structure to be brought to incandescence

with a relatively small current [71. A similar non-suspended heater would not be able to

reach the same operating temperatures since the substrate would act as a heat sink.

Suspended inductors decrease the capacitance of the metal lines to the substrate which

allows higher frequencies of operation with lower losses [6].

55
The Imal shape or tim suspenueu structure _st_etermlneutgyme geometry or tl_e

mask openings. These openings define the initial areas where the etching solution is

allowed to react with the stlbstrate. As the etch progresses, the masked areas extending

into the final etched rectangular area will be undercut. This undercutting is depicted in

Figures 2-4. The pit that eventu:dly forms is aligned to the primaWflat of the wafer and

is defined by the smallest rectangle th,'ttencompasses the mask opening. If the

encompassing rectangles around adjacent openings overlap, then the final pit is the

smallest rectangle that encompasses all of the overlapping openings. In all cases, the

final pit will be rectangular if left in the etching solution long enough. The shortest side

of the rectangle determines the depth of the pit, as the students will have discovered in the

prerequisite experinaent [1].

Figure 3 is an optical microgr:lphof an incompletely released cantilever. The

light reflects back into the microscope where the silicon is not fully etched from trader the

cantilever. The bottom of the pit also reflects the light straight up,showing a less distinct

spots through the glass of the cantileve,'. The area left to be etched is clearly outlined by

the contrast in the image. The cantilever in Figure 4 was broken away to clearly show the

progress of the etch as it undercuts the cantilever. If the etch were allowed to go to

completion, the pit would continue to etch down to pyramidal-shaped trench, and the

cantilever would be completely released. An optical microscope will not be able to focus

simultaneously on both the suspended structtlre and the bottom of the pit. Therefore, by

focusing alternately on the top and the bottom of the pit, the progress of the etch can be

monitored.

Figures 5 through 7 show several different designs for micromachined heaters.

Figure 5 shows a suspended structure called a "trampoline" [7]. This structure results

from the mask design shown in Figure 8(d). If rectangles are drawn around the mask

openings in Figure 8(d), they will overlap, so the resulting pit will encompass all four

openings. This effect is illustrated in Figure 5. Figure 6 shows a cantilever attached with

diagonal trampoline arlns at the end. This design also results in a single pit. To

demonstrate an incorrect design for the students, Figure 7 shows a cantilever which is

attached with right-angled arms. In this case the rectangles encompassing the openings

do not overlap, and so three separate pits are formed leaving the structure unsuspended.

This is similar to the test pattern in Figure 8(h).

Description of Test Die: The test die should contain some adaptation of the test

patterns depicted in Figure 8. These eight test patterns will challenge the students' ability

to predict the final shapes of the st,spended structures. Some patterns will yield obvious

56
suspended structures, such as cantilevers and trampolines. The patterns in Figures 8(c)

and 8(f) will produce cantilevers and the patterns in Figures 8(d) and 8(g) will produce

trampolines. However, some of the patterns will not yield suspended structures, for

example Figures 8(e) and 8(h).

If the design is submitted to MOSIS, the Orbit SCNA_MEMS or SCPE MEMS

process must be used [5]. If the test die can not be obtained through MOSIS, a suitable

alternative can be fabricated in a microelectronics laboratory. The initial silicon wafer

should be {100}-oriented. The patterns to be etched should be masked with silicon

dioxide. No specific oxidation schedule needs to be followed; however, the oxide should

be pin-hole free and at least 1 gm thick so the suspended oxide structures will survive the

rinsing process. An example wafer processing technique can be found in [8].

Etching Procedures: To successfully release suspended structures an additional

rinsing step must be added to the procedures outlined in the prerequisite experiment [1].

Each time the etch is stopped the following procedure should be followed to prevent the

suspended structures from breaking:

(1) Gently swirl the test die in a beaker of deionized water for two minutes to

rinse off the etching solution.

(2) Gently swirl the test die in methanol for two minutes to displace the water

from the etched pits.

(3) Set the test die aside to air dry. The drying process can be accelerated by

placing the test die on a 40°C hot plate for one minute.

Since methanol has a lower surface tension than water, it will pull down less

forcefully on the suspended structures as it ev:tporates. If the methanol is not used, the

structures may adhere to the bottom of the pit or break off entirely.

If EDP is used to etch the test die, then the etching should be done in ten minute

intervals to give the students a good look at how the etching progresses. If KOH is used,

then one minute intervals should be used. If the etching is to be resumed another day, the

test die should be re-dipped in the buffered HF solution [1], or the die can be left soaking

in methanol and dried off before resuming the etch.

Anticipated Results: Upon conclusion of the experiment, the students should

observe that some test patterns produce suspended structures, and some do not as might

57
have been mistakenly predicted. Referencing Figures 8 and 9, the following results

should be observed:

Pattern (a) is a repeat of the pattern used for the prerequisite experiment in bulk

silicon etching [1]. Students should correctly predict that it will etch into a square

pyramidal pit with no suspended features.

Pattern (b) is a square oriented at 45" to the primary wafer flat. It will etch into a

square pit with overhanging glass at the corners.

Pattern (c) will etch into two unconnected pits. The upper pit will have two

released cantilevers and an overhang at the top. The bottom pit will have a single

cantilever.

Pattern (d) will result in the trampoline structure over a single pit.

Pattern (e) will initially etch into a square torus supporting the square of glass in

the center on a pillar of unetched silicon. As the etch proceeds the ibillarwill get

narrower until the glass square isreleased and rinsed away in the etching solution. The

pit will continue to etch into a square pyramidal pit like pattern (a).

Pattern (f) will result in a cantilever suspended over a square pit similar to the

cantilevers depicted in Figures 3 and 4.

Pattern (g) will result in a suspended square of glass supported by two arms over a

square pit.

pattern (h) is similar to pattern (g), but it will result in four unconnected pits with

no suspended structure. In this case, the etch will terminate before the pits can join

together.

The students should also conclude that the full pit depth does not have to be

reached in order to fully release the structures. The time actually needed for full release

depends on the dimensions of the suspended structures and open areas.

Suggested Follow-on Experiments: The students should be prepared to design

and fabricate actual devices. For example, they could design, fabricate, and test some of

the devices in [5], such as the diving board cantilever (Figures 3 and 4) and the infrared

point source (Figure 5).

SOURCES OF SUPPLY: The routine chemical supplies and KOH are available

from Sigma Chemical Corp., P.O. Box 14508, St. Louis, MO 63178. The EDP can be

purchased already mixed from Transene Co., Inc., US Rt. 1,Rowley, MA 01969.

58
REFERENCES:

1. T.Jenkins,J. Comtois,and V.Bright,"Bulketchingofsiliconfor

micromachining,"NationalEducators'Workshop:Update1992,Standard

ExperimentsinEngineeringMaterialsScienceandTechnology,NASACP- ,

Nov. 1994.

2. J. Bryzek, K. Petersen, and W. McCulley, "Micromachines on the march," I. E.

E. E. Spectrum, pp. 20-31, May 1994.

3. G. Stix, "Micron machinations," Scientific American, pp. 107-117, Nov. 1992.

4. M. Mehregany, "Micromechanical systems," Circuits and Devices, pp. 14-22,

July 1993.

5. J. Marshall, M. Gaitan, M. Zaghloul, D. Novotny, V. Tryee, J.-I. Pi, C. Pifi_.,and

W. Hansford, "Realizing suspended structure on chips fabricated by CMOS

foundry processes through the MOSIS service," NISTIR 5402, U. S. Department

of Commerce, National Institute of Standards and Technology, June 1994.

6. J.Y.-C. Chang, A. A. Abidi, M. Gaitan, "Large suspended inductors on silicon

and their use in a 2 !am CMOS RF amplifier," I.E.E.E. Electron Device Letters',

vol. 14, pp. 246-248, May 1993.

7. J. Marshall, M. Parameswaran, M. Zaghloul, M. Gaitan, "High-level CAD melds

micromachined devices with foundries," Circuits and Devices, pp. 10-17, Nov.

1992.

8. T. Jenkins and E. Kolesar, "Laboratory experiments in integrated circuit

fabrication," NASA Conference Publication 3201, National Educators'

Workshop."Update 1992, Standard Experiments in Engineering Materials

Science and Technology, National Aeronautics and Space Administration Office

of Management, Scientific and Technical Information Program, pp. 235-270,

1993.

59
Thcrmolneler

Tight Lid

I II I

Lm-ger Bcakcr

Smaller Bcakcr

Watcr Bath

Water I_cvcl

I:3)P level

Stir Bin

Slin-ing Itotplatc

Figure 1. Diagram of lab-built reflux reactor [I].

1.2tchcd

Edge of Suspended ',_ Pit Glass Corner .v

1

Etch _ t2

Boundaries "_ t3

Figure 2. Example of etch progression as it undercuts the edges of a suspended glass

corner. The dashed lines illustrate the extent of the etched pit at successive times (t).

60
Figure 3. Undercut of glass cantilevers after 135 minutes in EDP at 85"C. The largest

cantilever is 135x250 btm.

Figure 4. 135x25()btrnglass cantilever partially etched in EDP ft_r135minutes at 85C.

The cantilever was broken olf to reveal the progress ol the etch. The pit is It)2x266 l.tm.

61
Figure 5. Suspended resistive heater using a trampoline structure. Tile center t_lthe

trampoline is 85x85 gm and the pit is 18()x180_m.

Figure 6. Suspended resistive heater using a cantilever structure with .,,upDu-tarms at 45"

angle. Tile cantilever is 95x1511_m and the pit is 18€1x2(1()bLm.

62
Figure 7. Result or"placing support arms at 90". The 95x1()3gm cantilever is not

released.

63
(a) (b) (c) (d) |

10 #m

m

(e) (0 (g) (n)

Figure 8. Suggested layout of test pattern masks. Mininlum spacing between mask

openings (indicated by black) is 10btm. The overall outer dimension of each test pattern

is 100x100 btm.

(a) (b) (c) (d) l

'

(e) (f) (g) (h)

Figure 9. Illustration of the final etched pit for each test pattern.

64
Thomas J. Jenkins Victor M. Bright

Captain Thomas J. Jenkins is a Victor M. Bright graduated magnacum

commissioned officer in The United laude with a BSEE degree from the

States Air Force. He is a research University of Colorado at Denver in

associate with the Department of 1986. In 1987 he entered the Graduate

Electrical and Computer Engineering at School of the Georgia Institute of

the Air Force Institute of Technology, Technology. He was awarded an MSEE

Wright-Patterson Air Force Base, Ohio. degree in 1989, and completed the PhD

He is assigned to the Solid State requirements in 1992. In 1992, he joined

Electronics Directorate, Wright the Department of Electrical and

Laboratory, Wright-Patterson Air Force Computer Engineering at the Air Force

Base, Ohio as a Device Processing Institute of Technology (AFIT), WrightResearch Engineer. He is the project Patterson AFB, where he is currently an

leader for the Advanced Heterojunction assistant professor. He is the chairman of

Bipolar Transistor Program and the Tri- the Electronic Device Technology

Service/Industry Heterojunction Bipolar Academic Sequence and the director of

Transistor Reliability Program. He is a the AFIT Electronic Materials and

member of Tau Beta Pi, Eta Kappa Nu, Microelectronic Device Research

Phi Kappa Phi, and the Institute of Laboratory. Dr Bright is a member of

Electrical and Electronics Engineers. Tau Beta Pi and the IEEE. Professor

Bright's current research interests

John H. Comtois include piezoelectric materials and

devices, microelectronics, microsensors,

Captain John H. Comtois is a and integrated optics.

commissioned officer in the United

States Air Force. He received a BSEE

degree from Carnegie-Mellon University

in Pittsburgh in 1983. After an

assignment as a programmer and

maintenance branch chief he attended

the Air Force Institute of Technology

(AFIT) to study electronic device

technology and VLSI, and received an

MSEE degree from AFIT in 1988. He

was then assigned to a radar evaluation

unit where he designed, built and

programmed communication interface

boards. He is currently back at AFIT

pursuing a PhD in the physics of

electronic devices, specializing in

microelectromechanical systems

(MEMS). He is researching the

integrationof MEMSwith VLSI devices

in high density multichip module

packages. He is a member of Tau Beta

Pi and an IEEE associate member.

65

DIMENSIONLESS FUN WITH FOAM

Edward L. Widener

MET Department

Purdue University

Knoy Hall - Room 119

West Lafayette, Indiana 47907

Telephone 317-494-7521

67
68
DIMENSIONLESSFUN WITH FOAM

EdwardL Widener- METDept.

SchoolofTechnology- PurdueUniversity

WestLafayette,IN 47907-1417

KEYWORDS: bubbles,capillaritydi , mensionalanalysis,filling,foaming,lather,

splashing,suds,surfacetension.

PREREQUISITEKNOWLEDGE:Forceinvolvesachangeofmomentum(mass

timesvelocity)withtime;moresimply,forceismasstimesacceleration.Tension

involvesforcespullinginoppositedirectionsona material.Studentsmay

recognizesurfacetensionas"capillarity"the, propertyofafluidwhentouchinga

boundaryorinterface.Bubbles,soapsuds,evenplasticfoams,arestrongly

influencedbysurfacetension,whichisa relativelyweakforce. Changingits

boundaries,compositions, ortemperaturesmaysignificantlychangethesurface tensionofthefluid.

OBJECTIVES:To teachthedifferencebetweensurfacetension(force/length)in

a liquidvstensilestrength(force/area)inasolid.To considercapillarity's

influenceonfoamformationandduration.To exploretheeffectofjet-velocityor

nozzle-locationonacontainer-fillingstationora garden-fountaindisplay.

INTRODUCTION:Materialslabsshouldincludeexperimentswithfluids(liquids,

aSes)aswellaswithsolids(crystals,glasses).Strangenewproperties

iscosity,capillarityshould ) augmentfamiliarconcepts(cohesion,adhesion).

The"impulse-momentumequat=onshould " replacean"energy-balanceif",

obviousfriction-lossesareunknown.Observinga '_ree-vortextrail " inopenchannelflowcanelucidateturbulenceandillustrateboundaryeffects.

Industrialprocessesofteninvolvefoam,froth,lather,or suds,whichare

maintainedbylow"surface-tensions(capillari " tyand ) dimensionedas'l=orceper

unit-length(Newton " s/metrePounds , /inch).Indeed,inStaticswestudybubbles

bydrawingfree-bodydiagrams;differentiatingbetweenspheres(drops)and

shells(bubbles);recognizingfoam-factors(additives,interfaces,temperatures);

andintroducingclassics(C.V.Boys,HunterRouse).

Sudsformationiseasytodemonstrate:1) Bottlesarehalf-filledwithhardor

softwater;adddetergentsinvariousamounts;corkandshakethebottles;then

measuretheheadofsuds;andtrydifferentwatertemperatures...2)Copious

frothingoccurswhenroot-beerisp.ouredovera scoopofice-creaminaglasstumbler;measurethehead;tryvanoustemperaturesandpour-rates...3)Intoa

panofwater,poura littlekeroseneor cookingoil,adda grainofdetergent,and

watchtheradialretreatofthatthin-film;tryothercleanersandsolvents;seewhich

worksbestatvarioustemperatures.

EQUIPMENT& SUPPLIES:1) Notebook&calculator,,,2)Ruler,withinchand

centimetredivisions...3)Setofsimilarbeakers(say4-6sizes)...4)Washtub,with

waterfaucets...5) Extensionhoseoroverheadpipe,tosendadownwardjetof

waterintoa beaker...6)Quick-closingvalve,atendofhose...7)Makeshifitems t

canbe substituted;e.g.,plastictub(sink),hoseclamp(valve),or pop-bottle

bottoms(beakers).

PROCEDURE:Fora simple-but-practical experiment,try fillingthecontainers

withaverticalstreamofwater.Anydeepsinkwithalever-faucetwilldo;

otherwise,riga hose-and-bucket setup.Usea matchedsetoftransparent

69
containers,withvaryingdiameter(d) andheight(h);beakers,jars,or bottlesare

fine. Whenwater-temperature(t)issteady,at constantvelocity(V),run thejet

into a containerandfillto overflowing;thenabruptlyshutoffthe faucet. With

enoughvelocityto giveaheadof foam,whichrapidlysubsides,watercannotfill

the beakercompletely. Clearly,the fallingjet entrainsairto makebubblesin

the beaker;the fasterthejet andlongerthe drop,the morethe bubblesand less

filling. Froma convenientdatum-plane,the inside-bottomof the beaker,measure

the finalheight(H) ofwaterin the beaker. Also,measurethe jet'sfree-falldistance

(D)fromfaucet-outletto beaker-bottom.Makeseveraltrials,confirmreproducible

results,and get a reliableaverage-height(H)for eachbeakertrial.

Somejars arefullerthanothers. Perhapsanotherjar-shape(J)would have

better"fillability"in a differentsize? Experimentnextwithvariousjet-distances,

velocities,andtemperatures.Takepainsto maintain"steady-state"conditions;

i.e.,constantwith time (-r). Althoughmoretrouble,try comparingdifferentfluids:

salt-brine,kerosene,glycerine,or detergentsin harderand softerwater;perhaps

awashing-machinewith "suds-saver"ishandyin the laundry. Obviously,fluids

vary in properties;i.e., density(g),viscosity(v),and capillarity(s). Gatheringa

varietyof datais aninterestingchallenge.

Nextcomesthe analysis.Theoptimaljar-size(formaximumfilling)

shouldbe foundfor eachjet-setting(of knownheight,velocity,temperature).The

obviousapplicationisat a container-fillingstation,wherevariousjet-distancesand

velocitiesmaybe neededfor variouscontainers. Hereiswherethe powerand

magicof"dimensionalanalysis"can beexploited,to directfurtherinvestigating

andto promoteefficientreporting.

ALTERNATIVES:Fora radicalchange,inverta beakerandcreatea "splashbubble".Thisphenomenonisthebasisofthose"shimmeringfountainssold " at

garden-shops.Averticalstreamofwater,strikinga disk,canproducea

beautiful,clearhemisphere,whichsmoothlycascadesintothepool.Students

expectingtosplatterclassmatesmayexperiencetheserendipityofdiscovery.

Justvaryingthewater-velocityandmeasuringtheresultantbubble-diamete(B) r

makesaneffectiveinvestigation, especiallyifjet-lengthsvary. Addingdetergent,

anothervariable,shouldreducesurface-tensionandprolongbubble-life.

DIMENSIONALANALYSIS:1)Withinsightintoa problem,recognizeall

significantvariables;avoidduplicatingfactors,whichobscureouranalysis...2)

Selecta basicsystemofunits,usuallyMass-Length-Timore Force-LengthTime...3)Adddimensionlessshape-factor(J),angle(Radian),ortemperature(t)

onlyifvariable...4)Systematicallyconsideyour r fluid'sGeometry,Motion,and

Forces...5)Identifyeverypertinentvariable,andexpresseachintermsof F-L-T;

e.g.,surfacetensionisF/L, velocityisL/T, viscosityisFT/A,A isLxL,andheight

is L...6)Choose3-variabletos representF-L-T;don'tuseourdependentvariable

(H)...7)Forexample,letsurfacetension(s=F/L) beF;letvelocity(V=L/I') beT;

andletdistance(D)be L...8)AsumeH isafunctiononlyof D,V,s,v;otherfactors

stayconstant(J,h/d, g,t)...9)Makedimensionlessgroupsorparameters(Piterms)by applyingBuckinghamor Rayleighmethodstosolvesimultaneous

equations;here,asimpleFactor-LabelmethodcangenerateourPi-terms(see

theAppendix).

Finally,wecanexploitsuchPi-terms:1)Thedependentvariable(H)can

bea functionof our othervariables(independents);hencea dependentPi-term

becomesafunctionof the remainingterms...2)A concisetwo-dimensionalplotof

our dimensionlessgroups (withseveralvariables)is nowfeasible...3)Plotshelp

organizemeasurements,providedirectionfor newtesting,andshowthe scopeof

results...4) Gapsarethenfilledin the testdata;check basicpremises...5)No

70
matterifothers useddifferentunits;dimensionlessplotsof similartest-resultsare

directlycomparable.

APPENDIX:Let Hbe afunctionof J,d,h,D,V,s,v;letD,V,srepresentL,T,F. Then

Pi-1=(v)(1/s)(V) =(FT/LL)(L/F)(L/'I');Pi-2=(H)(1/D_)=(L)(1/L); and P-,3=h/d

=constant. So,our testsareplottedas H/D (ony-axis)versusvV/s (onx-axis),

for afamilyof h/d jars (or J-shapes).

REFERENCES:

1 Boys, Rouse,C.V., Hunter, "Soap-Bubbles: "ElementaryColours Mechanics andofForces", Fluids",Dover JohnWiley Inc, NY, & Sons, 1959.NY, 1946.

3) AIIman,W.F.,"TheFascinatingPhysicsof Fizz",U.S.News& WorldReport, Nov.20,1989.

4) Langhaar,H.L, "DimensionalAnalysisandTheoryof Models",JohnWiley&

Sons,NY,1951.

5) Ipsen,D.C.,"Units,Dimensions,and DimensionlessNumbers:The Pitfalls",

McGraw-Hill,N.Y.,1960.

6) Widener,E.L, "DimensionalAnalysisfor UndergraduateLabs",JointConf.of

N.Central/IN/ILSections,ASEE.

EDWARD L. WIDENER

Since 1978,ProfessorWidenerhastaughtapplied

coursesin MechanicalEngineeringTechnologyat

PurdueUniversity,concentratingonmaterialsand

processes,fluidmechanics,labs,andtechnical

writing.Between 1974-77hetaughtnightclassesin

Indianapolis(IUPUI) andDanville,IL(Jr. College).

He is a registeredprofessionalengineerin NewYork

andIndiana,holdingmembershipsinASEE,ASME,

ASM,ISA,andTAPPI. From1983-92,he hasbeen an

ABETvisitorforASMEandTMI. Degreesfrom

PurdueareBS '49(physics)andBS '51(ME).

MSEM'62(hydraulicsis) fromKansas.From

1952-78,he wasaprocessor projectengineerfor

ContinentalGroup;Baker-McHeury-Welch;KimberlyClark;E.I.Dupont;UnionCarbide;andU.S.Steel.

71

INTRODUCTION TO NONDESTRUCTIVE TESTING

David E. Werstler

Engineering Technology Department

Western Washington University

Bellingham, Washington 98225-9086

Telephone 206-650-3447

73
74
INTRODUCTION TO NONDESTRUCTIVE TESTING

David E. Werstler

Manufacturing Engineering Technology

Western Washington University

Key Words: Fracture toughness, critical crack size, ultrasonics, electromagnetics,

process flaws.

Prerequisite Knowledge: This experiment should follow a discussion of fracture

mechanics, which usually occurs early in an introductory materials course. The

student should have prior knowledge of electrical and magnetic theory from a

physics course. If more specific discussion of electrical and magnetic properties

and failure analysis is presented later in this course or in a second course, this

experiment should be delayed until that time.

Objective: To utilize standard test methods for finding flaws in materials and

determine the chance that these flaws will result in catastrophic failure.

Equipment:

1. Ultrasonic instrument preset for frequency and materialthickness,

2. Ultrasonic transducer, typically 5 MHz and .5" diameter,

3. Couplant (30 wt oil, clear grease, or water-based gell),

4. Aluminum billet stock with artificial flaws and a reference hole in one end,

5. Test bench with power supply for magnetizing a part,

6. Magnetic particles,

7. Steel part with reference notches of known depth and with unkown defects,

8. Conductivity meter with ID probe,

9. Set of standard aluminum, brass, and stainless steel nuts with the same ID as

the probe and with varying diameters and hardness,

10. Box of aluminum nuts of the same type as the standards, some with flaws.

Introduction: All materials contain some flaws. We need to know the maximum

size flaws that a material can tolerate for the intended stresses that it will experience in service, in order to prevent fatigue or brittle catastrophic failure. We now

have a property called fracture toughness that is usefull in this regard. Test

methods to accurately measure flaw size are a critical part of this analysis.

Ultrasonic testing (UT) sends a high frequency (1 to 25 MHz) sound pulse

into a material and waits for it to return in the pulse-echo mode. Time is used as a

measure of the distance that the sound travels. A reflection from the opposite side

of a part takes longer to return than the reflection from an internal defect. An oscilloscope which displays time (distance) horizontally and sound intensity vertically will

"/5
display a spike on the left where some sound reflects from the front surface, a spike

on the right from the back surface reflections, and spikes from defects in between.

Magnetic particle testing (MT) can only be used with ferromagnetic materials,

primarily steels, because it requires that most magnetic flux lines are contained

within a part except where a defect is present near the surface. Flux lines that are

forced outward near the defect then can attract magnetic particles that are lightly

blown onto the surface. These particles are dyed bright colors so that concentrations of them are easily seen. The size of the defect is determined by the size of the

pile of particles and the amperage used to magnetize the part.

Eddy current testing (ET) also is usefull for finding surface defects and

depends upon the electromagnetic properties of the material being tested. An

alternating current flowing in a small coil will be disturbed by interactions with the

material being tested. As the coil is moved along the surface of a part, the disturbance should remain constant. A change indicates a possible flaw or alternatively a

change in the composition, microstructure, properties, or surface condition of the

material. (For more details, see Askeland or ASM Handbook Vol. 17.)

Procedure:

Ultrasonic Testing

1. Switch on the UT instrument. Note the location of the coarse and fine gain

switches, which are the only settings that need to be changed.

2. Apply couplant to the top of the aluminum billet stock, and place the transducer

on the billet near the reference hole. Two spikes should appear on the screen.

Note that the distance between the spikes on the screen scale is proportional to the

thickness of the block.

3. Move the transducer over the reference hole and adjust the gain so that its

spike peaks at about mid-height on the screen. This establishes a calibration level

for size of defect based upon the reflecting area. Note that hand pressure has a

large effect.

4. Increase the gain for scanning and slowly sweep back and forth until you have

covered the entire top of the block. Mark the location of suspected defects.

5. Return the gain to the calibration level and estimate the size of defects as a

ratio of the reference level. Make a map of the location and size of defects.

Compare with a radiograph provided by the instructor. Which of these defects might

cause brittle failure if it were on or near the surface of a part machined from this

block?

MagneticParticleTesting

1. Switch on the ultraviolet lamp to let itwarm up for 2 minutes. Warning: this

lamp can get very hot -- you can burn yourself! Turn it off when you are finished.

2. Lock the test part into the test bench, being sure that there is good electrical

contact on the copper pads. Waming: poor contact may result in arcing.

3. Switch the power supply on and note the amperage. Spray particles onto the

top surface for three seconds, then switch the power off. With the black light, look

?6
for and record defects. With your finger wipe the defect indications and note if they

reform.

4. Turn the part over and repeat the inspection. Which defects are likely to cause

brittle failure?

Eddy Current Testing

1. Calibrate the conductivity meter and probe with standard aluminum nuts that

represent the allowable range of inside diameter and hardness. Note the range of

conductivity that is considered to be normal. Compare this with nuts made of brass

and stainless steel.

2. Check the rest of the aluminum nuts that are provided. If any are out of the

calibration range, how might you determine the type of defect that is present?

Notes to the Instructor: To many faculty this experiment may appear to be too

mundane and non-scientific, but it has some hidden attributes. First, the objective of

finding flaws and considering their potential danger needs to be strongly reinforced.

My 20 years of experience in failure analysis suggests that too many engineers

assume that safety factors account for all material flaws or even that flaws are not

relevant to design. Second, it is a good example of utilizing physical properties for

unusual applications. We need to broaden students perspective on the relevancy

of all properties and avoid inculcating limited paradigms if we want them to be more

effective in their professional careers.

There are nine weekly lab projects in my one quarter introductory materials

course, which emphasize the relationship between structure, properties, and

processes:

1. tensile testing of steel, aluminum, and a polymer;

2. Charpy testing of annealed mild steel keystock;

3. microstructure and processing of a nail;

4. nondestructive testing;

5. compressive strength of various mixtures of concrete;

6. age hardening of 2024 aluminum;

7. designing aluminum, composite, and wood beams;

8. microwave sintering of tungsten carbide machining inserts; and

9. shear strength of adhesives.

These lab projects were selected to meet most of these criteria:

1. emphasize a lecture topic,

2. low cost and utilize existing equipment,

3. complimentary to other experiments,

4. correlate to other courses,

5. demonstrate emerging technologies, and

6. take advantage of common experience.

?7
The equipment may be the biggest problem for many faculty, since most

universities do not have it available. Iwas able to obtain donations from defense

contractors that are downsizing. Your local chapter of ASNT (American Society for

Nondestructive Testing) would be a good place to start for donations. MT is the

cheapest, since a test bench can be fabricated from a woodworker's vise ($100) and

a scavenged power supply with an output of at least 500 amps at 12 volts; or a

portable yoke magnet can be purchased for $500. The visible powder costs about

$4/Ib. A black light and fluorescent powder adds about $200 but with an improvement in sensitivity. My test bar is an automotive camshaft that I scrounged from a

local auto shop, and an old lawnmower blade is ideal. No defects were present, so I

made some craze-cracks on the hardened lobes by quenching. A diamond saw or

laser can be used to create reference defects.

UT instruments and a small assortment of transducers cost a minimum of

$7,000, but some manufacturers give educational discounts. ET scopes are also in

the same price range, but a $2,000 conductivity meter can be used. A few vendors

sell cards that turn a computer into a UT or ET instrument. Test blocks for these

methods can be made from aluminum billets with defects provided by drilling. 10to

.25 in. dia. holes or sawing slots followed by plugging or filling so that they are not

visible. Reference holes should be left visible so that students can accurately

calibrate the equipment. A radiograph or drawing of the block should be provided

after performing the inspection so that students can check and comment on their

results in their written report.

There are many other methods of NDT that can be used. I like to use two

methods in the experiment: one for surface and one for internal flaws. Radiography

is a lot of fun and gives good detail but is too dangerous for younger students. I use

it only in an advanced class. Dye penetrant is cheap and easy to use but very

messy -- students quickly have dye on everything. And it doesn't utilize interesting

properties. Acoustic-emission instruments may be available from research projects,

but otherwise are too expensive and specialized to consider.

References:

Askeland, Donald R.: The Science and Engineering of Materials, 3rd Ed., PWS

Publ. Co., 1994, pp. 771-783.

Nondestructive Inspection and Quality Control,ASM Handbook Vol. 17, Ninth Ed.,

ASM, 1989.

Sastri, Sankar: Fluorescent Penetrant Inspection; Magnetic Particle Inspection;

Radiographic Inspection; National Educators' Workshop: Update 88, NASA

Conference Publication 3060, 1990.

?8
PC LASER PRINTER-GENERATED CUBIC

STEREOGRAPHIC PROJECTIONS WITH

ACCOMPANYING STUDENT EXERCISE

Paul J. Coyne, Jr.

Glenn S. Kohne

Wayne L. Elban

Department of Electrical Engineering and Engineering Science

Loyola College

4501 North Charles Street

Baltimore, Maryland 21210-2699

Telephone 410-617-2512

79
80
PC LASER PRINTER-GENERATED CUBIC STEREOGRAPHIC PROJECTIONS

WITH ACCOMPANYING STUDENT EXERCISE

Paul J. Coyne, Jr., Glenn S. Kohne, and Wayne L. Elban

Department of Electrical Engineering and Engineering Science

Loyola College, Baltimore, Maryland 21210

ABSTRACT: A technique for computer generation of arbitrary cubic stereographic

projections using a Hewlett Packard LaserJet Series II laser printer, with extended

TM

memory, is described. The procedure uses an IBM Basic, Version 1.10 by Microsoft

TlVl

Corporation , program which provides the laser printer machine codes to generate

individual spots, lines, circles, or alphanumerics at arbitrary locations. The program

requires the operator to select a central plane pole and two other plane poles such that a

right-hand vector cross product of these plane poles will generate the central plane pole.

In addition, an input ASCII file of selected plane poles is required. An optional request

for the corresponding great circle belonging to each selected plane pole can be made in

the input ASCII file. A brief review of the use of stereographic projections for the cubic

system is followed by an overview of the procedures necessary to generate a plot. An

example student exercise is presented.

KEY WORDS: crystallography, cubic crystals, Miller indices, stereographic projection,

Wulff net.

PREREQUISITE KNOWLEDGE: crystallography of the cubic system and exposure

to the use of standard cubic stereographic projections for determining the angle between

planes (or the normals to these planes) which can be covered in a first course in materials

science at the sophomore level and studied in more detail in an upper-level undergraduate

crystallography course (Instructor Note 1).

OBJECTIVES: To reinforce basic crystallographic concepts for the cubic system on a

stereographic projection basis using a computerized technique to generate arbitrary

81
projections easily and inexpensively; to detail an implementation of this technique; and to

provide an example student exercise demonstrating the use of stereographic projections

and their manipulation preparatory to solving applied crystallography problems.

TM

EQUIPMENT: (1) an IBM personal computer, 8088, using DOS Version 3.0; (2) the

T1M

BASICA interpreter, Version 1.10 by Microsoft Corporation ; (3) a Hewlett Packard

'I'M

LaserJet Series II laser printer, with extended memory; (4) a Wulff net; (5) a protractor.

PROCEDURE:

Introduction

In any crystal structure, planes and directions can be specified in terms of integers

known as Miller indices [1]. The Miller indices for a plane, (hkl), can be found by

inverting the intercepts, in terms of the dimension of the unit cell, of the plane with the

primary axis system, cleared of fractions and common multipliers. Figure 1 illustrates

this for the (120) plane in the cubic system. The Miller indices for a direction, [uvw], can

be found by translating the direction to the comer of a unit cell and recording the

direction, in terms of the dimension of the unit cell, with reference to the primary axes.

Figure 1 also illustrates the [120] direction in the cubic system. The subsequent

discussion will be limited to cubic crystals where the normal to the (abc) plane is given

by the [abc] direction.

A stereographic projection [2,3] is a two-dimensionalrepresentation of the threedimensional relationship between planes and directions for a given crystal system. The

geometric relationship between the planes in the cubic system can be visualized in terms

of the actual planes or the normals to the planes. The normal to a plane is referred to as a

plane pole (Figure 2). The angle between plane 1 and plane 2, angle 01, is numerically

equal to the angle between the respective plane poles, angle 02. The intersection of each

plane with a sphericalsurface generates a great circle. A great circle has a diameter equal

to the sphere diameter. The intersection of the companion plane pole with the spherical

surface generates a point which is normal to the plane-great circle. This can be measured

on another great circle containing the plane pole-point and a point on the corresponding

plane-great circle as shown in Figure 3. The projection of the plane-great circles and

82
Z

_

(I/1,1/i/2,1/_)

or (120) plane

1

_Y I

1 2

1

I I [120] direction

unit cell

2 dimension

Figure 1. Miller indices example for the cubic system.

83
plane pole 1

plane pole 2 angle e 1

plane 2

i angle e 2

-.J

plane 1

Figure2. Planepoleexamples.

84
plane pole

900 on great circle

plane great circle

Figure3.Intersectionof planeandits polewitha sphere.

85
planepole-pointsfromthe surfaceof the sphereto a planesurfacecreatesa stereographic

projection[4,5].

The plane pole at the center of a stereographic projection has its corresponding

plane-great circle as the exterior circle which is the outside boundary of the projection.

The assignment of a second direction will fix the orientation of the particular projection.

Figure 4 illustratesthis for a central [001] pole and two other poles which form a righthanded coordinate system. The corresponding great circle for each pole is also noted.

The angle between any two planes can be determined from a stereographic projection

containing both plane poles by positioning both plane poles on the same great circle,

superimposing the circle on a Wulff net [6,7], to measure the angle. Figure 4 also

contains the []'01] plane pole and corresponding great circle. The angle between the

[101] plane pole and the [111] plane pole can be determined from the (]'01) great circle

using the Wulff net or alternatively the equation below. The angle between the (hlklll)

and (h2k212)planes, which is equivalent to the angle between the [UlVIW1] and [u2v2w2]

directions, is given by

angle=c°s-l((hl*h2+kl*k2+ll*12)/((h12+k12+l12))(h22+k22+122)) 112 ). (1)

The theoretical basis for the computer generation of stereographic projections has

been detailed by Johari and Buchanan [8],Johari and Thomas [9], Kosel [10,11], and

Staley [12,13]. Given a particular [hkl] plane pole, the location of this pole on a

particular stereographic projection can be determined by first computing the cosine of the

angle, between the [hkl] direction and each axis of the right-handed coordinate system of

the desired stereographic projection. The central plane pole for this technique is

designated as [abc], while the other plane poles which define the orientation are

designated as [def] and [uvw]. The vector cross product of the second set must generate

the central plane pole (i.e., [def] x [uvw] = [abc]). Equation (2), which is configured for

the central pole, [abc], of the desired projection, is used to compute the cosine of the

angle between [hkl] and [abc], designated as a, following the notation of Kosel [10].

cos(_) = (h*a+k*b+l*c)/((h2+ k2+ 12))(a2+ b2+c2)) 1t2 (2).

86
(OOi)greatcircle

O) greatcircle

010

001

101

o

35,3

(I00)greatclrcle

(_01) great clrcle

I00

Figure 4. (001) cubic stereographic projection

87
The other two angles are designated [10] as 5, relative to the [def] direction, and It,

relative to the [uvw] direction. Given these angles, the location of any plane pole on the

particular projection can be computed using the equations below which generate an x-y

location on the given stereographic projection relative to an origin in laser printer

coordinates (XP,YP), where R is the radius of the projection in laser printer coordinates

and AR is the aspect ratio for locating positions along the y-axis:

Xlocation = R'cos( kt)/(1.0 + cos( o_)), and (3)

Ylocation = R*AR*cos( _5)/(1.0 + cos( _ )). (4)

Figure 5 illustrates the stereographic projection with the following indicated: (1) x-y

directions; (2) coordinate system origin in laser printer coordinates (0,0); and (3)

stereographic projection origin (XP,YP). Any plane pole which generates an x-y location

which would fall outside the great circle belonging to the central plane pole, which is the

boundary of the projection, corresponds to a plane pole whose location would be on the

back of the sphere and thus would not appear on the desired projection. A great circle

corresponding to a given plane pole can then be drawn by locating points on the circle

and displaying only those points which would appear on the projection.

Plot Generation

TM

The original Basic program was developed on an IBM PC/XT computer with

TM

DOS Version 3.10 and using the accompanying Version 1.10 by Microsoft Corporation

TM

BASICA.COM Basic language interpreter. The Hewlett Packard LaserJet Series II

laser printer with 2.56 Mbytes of internal memory, connected to the computer using a

parallel interface, and configured to factory default settings was used to generate hard

copies of the stereographic projection (Instructor Note 2). The program appears in

Appendix A.

The program is loaded and started using the Basic language interpreter. The user

must enter the central plane pole first, [abc] in the program, with a comma between each

digit. Two other plane poles, [def] and [uvw] in the program, must also be entered with a

comma between each digit. Next, the user is given the option of displaying the pole

indexes, with a bar over a number indicating a negative number. The user is next asked

to enter a file name for the ASCII file which contains a list of the plane poles to be

88
f laser printer origin

(0,0) (abc) great circle

(XP_P) Xlocatioon

co_l _ I c°vwl

[def]

Figure 5. [abc] stereographic projection with coordinate system identified.

89
included in the plot. This file is created beforehand using one of the text editors which

accompanies DOS, EDIT.COM or EDLIN.COM. The file must contain one plane pole

per line with a comma separating the numbers, a negative index should be preceded by a

minus sign. An additional digit, preceded by a comma, must be included to specify

whether the corresponding great circle will be included in the plot. If this last number is a

"0" the great circle will not be plotted. While other entries are possible, the program

suggeststhat a "1" be included when the drawing of a great circle is desired. The last line

of this file must be four zeros separated by commas. Any poles which are included in

this file that would not correctly appear on the projection that was requested are ignored

by the program. Appendix Bcontains an example ASCII file.

EXAMPLE STUDENT EXERCISE (Instructor Note 3):

After a review of classroom material on Miller indices, stereographic projections,

and the use of aWulff net, the following exercises are assigned:

(1) generate one of three standard projections (100), (010), or (001); this

requires the selection of the other two axes such that the vector cross product

generates the central pole with the use of ASCII file hklalll, which contains alI

possible plane poles containing -1, 0, or 1 (Instructor Note 4).

(2) determine the angle between two specific plane poles using both Equation (1)

and a Wulff net.

(3) sketch both great circles belonging to these poles and using a protractor to

measure the angle between the tangents of these great circles at the point of

intersection which is equal to the angle computed using Equation (1) and the

angle measured with the Wulff net.

(4) start with a (001) projection with only (hkl) that are -1,0, or 1 and then

establish the rotations undergone by selected poles to create a (011) projection

with similar hkrs and then obtain it.

(5) determine the rotation of the above (011) projection that would be required to

generate a (111) projection and then obtain it.

90
SAMPLE PLOTS AND RESULTS:

The (001) standardprojection, where [def] = [100] and [uvw] = [010], appears in

Figure 6. The great circles corresponding to the (011) and (111) plane poles are shown.

The angle between these planes can be determined to be 35.3° using Equation (1) or the

Wulff net using the great circle corresponding to the (0T1)plane pole. The corresponding

great circle tangents are also sketched with the angle measurement indicated.

Additionally, the rotations necessary for three selected poles to create a (011) projection

are indicated. A resulting (011)standard projection, where [def]= [100] and

[uvw] = [01_], is given in Figure 7. Included are the rotations necessary to create a (111)

standard projection for three selected poles. Figure 8 shows this new projection, where

[def]= [2ii'1 and [uvw] = [01_].

INSTRUCTOR NOTES:

(1) Although no longer covered in most introductory materials science textbooks,

stereographic projections are a powerful tool to examine geometric relationships between

crystal planes and directions. It is useful for sophomore students to become acquainted

with stereographic projections in a laboratory exercise in order to become more familiar

with the crystallographic topics covered in one or more accompanying lectures.

Generally, students grasp fundamental aspects but often lack the confidence to solve

applied problems in crystallography. However, this is remedied when students encounter

the use of stereographic projections in subsequent upper-level materials science courses

(e.g., companion paper in this Workshop [14].

(2) The only major consideration with this procedure is that the density of plotting is

limited by the amount of random access memory in the printer. This can be overcome by

increasing memory, but there is some upper limit dictated by individual machines. The

original code was developed for an early-model PC and laser printer. In lieu of tracing

the technology of the PC and the evolution of laser printers, a current-day PC and printer

were tested for compatibility. An IBM PS/Value Point 425/SX PC running DOS 5.0 and

Windows 3.1 was used for testing. The DOS directory contains a Basic interpreter

TM

IBM Basic Ver. a3.4 which is the file BASICA.COM. In addition, a Hewlett Packard

TM

LaserJet IIIP , using Printer Control Language 5 (PCL5), was used to generate hard

copies. Following the same procedures detailed in the section on Plot Generation will

91
(alxz)=(0 , 0 , 1 ) (def)=(1 , 0 , 0 ) (uvw):(0 , 1 , 0 )

ioo

.,......-- 4o,- o, ....,

.. ",.. .- .

• .

• .

• .

• .

•"" .:-4-_ (011 ) Plane --

-- %0

• _ (111) Plane

iOl.

I--'111 I _Jl_---------..__j.

i n

8[0 0_i" 001 011 01o

I I I -_ I

• 0

45 Rotation

I I

• i__- 0 /•

353 o

"-

"._o

l •

"°'''''•''o °•• • --••••-•°•

o•• .•

°°.° _.•.••.•**•

Figure 6. (001) cubic standard projection.

92
(abc)=(0 , 1 , 1 ) (def)=(1 , 0 , 0 ) (uvw)=(0 , 1 ,-i )

ioo

...,--4---,....

+.o+ ...

.. °.o

e. •

• °

• o.

e

,m •

iol _o i I

_. •

I

8-11 001 011 010 011 | m |

0 o

I •

35.3° Rotation

1(31 ii0 m I

_ .°

e

°e°'''e°''e° "" " "e • ° ° • • .° ° °+ "° " • +'°''e'''°

°'°-e. • °.. _i_ _.+...°'°

Figure 7. (011) cubic standard projection.

93
(abc)=(1 , 1 , 1 ) (def)=(2 ,-i ,-i ) (uvw)=(0 , 1 ,-i )

,,,,oooo,,°o,

ioOe ele° O°oo

oo °o • •

• o°

Ioi-" "._Io

oOIF °o

• Oo

|

Ol_l

I

001 010

I | °

o_

i01 110

o •

Ill llZ

I •

i00

I

°°Oo

•.llo lot" -g.

ee°eeOol oeoo e°e° ",,, 2Tff. ,,'"

oOoeo.4, oo. oe°

Figure 8. (1 11) cubic standard projection.

94
create the same stereographic projections, but there is still a memory limitation. The key

feature for portability is the laser printer. Any printer which supports PCL5 should

generate the same projections given that the connected PC can generate the same

sequence of characters asthe program in Appendix A. The original code was developed

before PCL5 was established, but upward compatibility was maintained by Hewlett

Packard as its laser printer family developed.

(3) A number of additional crystallography problems with solutions are provided by

Moon [15].

(4) The (100), (010), and (001) projections are generated using the program in Appendix

A and the input ASCII file, referred to as hklall1, in Appendix B. The program in

Appendix A can be easily adapted to the tetragonal and orthorhombic crystal systems.

This will require the generation ofseparate plane pole and direction plots.

REFERENCES:

[1] Van Vlack, L. H.: Elements of MaterialsScience andEngineering,Fifth Edition.

Addison-Wesley Publishing Company, Inc., 1985, pp. 84-90.

[2] Cullity, B. D.: Elements of X-rayDiffraction,Second Edition. Addison-Wesley

Publishing Company, Inc., 1987, pp. 63-78.

[3]Barrett,C.; andMassalski,T.B.: Structureof MetalsCry_stallom'aphicMethods.

PrinciplesandData,ThirdRevisedEdition.PergamonPress, 1980,pp. 30-43.

[4] Cullity, B. D.: ._Qp__.___ p. 65. L.,

[5] Barrett, C.; and Massalski, T. B.: _, p. 32.

[6]Cullity, B. D.: 9.P_,_..€_., P. 67.

[7] Barrett, C.; and Massalski, T. B.: _, p. 35.

95
[8] Johafi, O.; and Buchanan, W.: Computer Program for Obtaining Standard Projections

of Planes and Directions in AnyCrystal System. Trans. Met. Soc. AIME, vol. 236, no.

12, 1966, pp. 1760-1761.

[9]Johari, O.; and Thomas, G.: The Stereographic Projection and Its Applications.

Techniques of Metals Research, Editor: Bunshah, R. F., Volume IIA, Interscience

Publishers, 1969.

[10]Kosel,T. H.,:ComputationalTechniquesfor StereographicProjection.J. Mater.

Sci.,vol. 19,no. 12, 1984,pp. 4106-4118.

[11] Kosel, T. H., : Microcomputer Stereographic Projection. J. Metals, vol. 37, no. 3,

1985, pp. 56-57.

[12] Staley, J. T.: PC Program for Materials Science - Part II. J. Metals, vol. 37, no. 3,

1985,p. 71.

[13] Staley,J. T.: PC Program for Materials Science - Part III.J. Metals, vol. 37, no. 4,

1985, p. 76.

[14] Elban, W. L.: Stereographic Projection Analysis of Fracture Plane Traces in Polished

Silicon Wafers for Integrated Circuits. National Educators' Workshop: Update 94, NASA

CP- . 1994.

[15] Moon,J. R.: Worked Examples in Stereographic Projection. Monograph No. 2, The

Institution of Metallurgists, 1978.

SOURCES OF SUPPLIES (1994 Prices): The Wulff net, made of plastic, is available

from Polycrystal Book Service, P. O. Box 3439, Dayton, OH 45401-3439 at a cost of

$20.00. A few (i.e., (001), (111), (211), (011), and (130)) standard cubic projections (18

cm diameter) can also be purchased from Polycrystal for $15.00 each.

ACKNOWLEDGMENT: The Office of Naval Research under Work Request Number

N00014-87-K-0175 originally funded software development to create stereographic

projections for orthorhombic ammonium perchlorate crystals. Subsequently, the software

was modified to create cubic projections for instructional purposes.

96
APPENDIX A:

Program CUBICSP. BAS

1 REM STEREOGRAPHIC PROJECTION

10 REM CUBIC CRYSTAL LASER OUTPUT

20 X=I !

30 Y=I!

40 Z=I!

45 PRINT "PUT LASER PRINTER ON LINE "

50 PRINT "ENTER THREE PERPENDICULAR PLANES WHOSE NORMALS SATISFY "

60 PRINT" [def] X [uvw] = [abc]"

70 INPUT "(abc)" ;A,B ,C

80 INPUT "(def)";D,E,F

90 INPUT "(uvw)";U,V,W

92 PRINT "DO YOU WISH TO DISPLAY POLE INDEXES (Y=I N-0) "; : INPUT ANS

94 PRINT "INPUT (hkl) FILE NAME => "; : INPUT F$

95 REM SET LASER PRINTER FOR LETTER SIZE,NO TOP MARGIN,AND H+V SPACING

96 PRINT "HOW MANY COPIES ? "; : INPUT ICOUNT

97 FOR I=l TO ICOUNT

98 OPEN "I",#1,F$

100 LPRINT CHR$(27)+"&12a0elC": LPRINT CHR$(27)+"&klH"

105 R=475 'radius of circle

106 TH=6.3 'angle,in radians, for complete circle draw

107 AR=.4 'aspect ratio for Laser Printer

108 DELTH=250! 'default TH increment factor

110 XLOC=475: YLOC=275: RAD=475: GOSUB 1000 'draw major circle

115 GOSUB 5000 ' locate three major poles on circle

120 X2=X*X : Y2=Y*Y : Z2=Z*Z

130 CI=SQR( A*AJX2 + B'B/Y2 + C*C/Z2 )

140 C2=SQR( U*U/X2 + V'V/Y2 + W*W/Z2 )

150 C3=SQR( D'D/X2 + E'ElY2 + F*F/Z2 )

160 INPUT #1,H,K,L,DGC

162 IF (H=0) THEN IF (K=0) THEN IF (L=0) THEN GOTO 9000 'end of input file

170 H2=H*H : HA=H*A : HU=H*U : HD=H*D

190 K2=K*K : KB=K*B : KV=K*V : KE=K*E

210 L2=L*L • LC=L*C : LW=L*W : LF=L*F

215 C4=SQR( H2/X2 + K2/Y2 + L2/Z2 )

220 COAL=( HA/X2 + KB/Y2 + LC/Z2 )1(C 1"C4 )

230 COMU=( HU/X2 + KV/Y2 + LW/Z2 )/( C2"C4 )

240 CODE=( HD/X2 + KE/Y2 + LF/Z2 )/( C3"C4 )

242 AAL=ABS(COAL)

245 IF (AAL<I.00001 AND AAL>.99999) GOTO 330' (abc) and compliment are ignored

250 XP=475+INT((R*COMU/(1 !+COAL))+.5)

260 YP=275+INT((R*AR*CODE/(1 !+COAL))+.5)

264 AXP=XP-475

265 AYP=(YP-275)/AR : RAXY=INT(SQR(AXP*AXP+AYP*AYP)+.5)

266 IF( RAXY> 476 ) GOTO 330' pole on back projection, ignore.

267 XLOC=XP: YLOC=YP: GOSUB 4000 ' plot pole

269 IF(DGC=0) GOTO 330' do not draw great circle

270 IF(COAL=0) THEN GOSUB 3000' projection of circle is a straight line

271 IF (COAL=0) GOTO 330

97
272 XP=XP-475 :YP=(YP-275)*(1YAR) :RGC=INT(R/ABS(COAL)+.5)

273 DOC=R*ABS(SQR(1-COAL*COAL)/COAL) :IF(RGC> 1500) THEN DELTH=1000!

274 XC=475+INT(DOC*XP/SQR(XP*XP+YP*YP)+.5)

275 YC=275+INT(AR*DOC*YP/SQR(XP*XP+YP*YP)+.5)

276 XLOC=XC: YLOC=YC: RAD=RGC: GOSUB 2000' draw great circle

280 DELTH=250 !

330 GOTO 160

400 LPRINT CHR$(27)+"&10H"

405 CLOSE #1

410 NEXT I

420 GOTO 9999

1000REM CIRCLE DRAW SUBROUTINE

1010 DTH=0!

1020C$=STR$(INT(XLOC+RAD*1!*SIN(DTH)+.5))

1030R$=STR$(INT(YLOC+RAD*AR*COS(DTH)+.5))

1040 LPRINT CHR$(27)+"&a"+R$+"r"+C$+"C";: LPRINT "."

1050 DTH=DTH+TH/250 !

1060 IF(DTH<=TH) GOTO 1020

1100RETURN

2000 REM ARC DRAW SUBROUTINE

2010 DTH=0!

2020 CN=INT(XLOC+RAD*1!*SIN(DTH)+.5)

2025 CNC--CN-475

2030 RN=INT(YLOC+RAD*AR*COS(DTH)+.5)

2035 RNR=(RN-275)/AR

2040 IF(SQR(CNC*CNC+RNR*RNR) > 475) GOTO 2080

2050 C$=STR$(CN)

2060 R$=STR$(RN)

2070 LPRINT CHR$(27)+"&a"+R$+"r"+C$+"C";:LPRINT "."

2080 DTH=DTH+TH/DELTH

2090 IF(DTH<=TH) GOTO 2020

2999 RETURN

3000 REM LINE DRAw SUBROUTINE

3005 Pl=475+AYP : Ql=275-AXP*AR • P2=475-AYP : Q2=275+AXP*AR

3010 DP=(P2-P1)/100! : DQ=(Q2-Q1)/100!

3012 FOR I=0 TO 100

3015 P1R=P1-475 : Q1R=(Q1-275)/AR

3016 RPQ=SQR(P1R*P1R+Q1R*Q1R)

3017 IF( RPQ > 475 ) GOTO 3040

3020 C$=STR$(INT(P1)) : R$=STR$(INT(Q1))

3030 LPRINT CHR$(27)+"&a"+R$+"r"+C$+"C"; : LPRINT "."

3040 PI=PI+DP : QI=QI+DQ

3100 NEXT I

3500 RETURN

4000 REM POINT DRAW SUBROUTINE

4010 FOR IX=XLOC-1 TO XLOC+I

4020 FOR IY=YLOC-1 TO YLOC+1

4030 C$=STR$(INT(IX)) :R$=STR$(INT(IY))

4040 LPRINT CHR$(27)+"&a"+R$+"r"+C$+"C"; : LPRINT "."

4050 NEXT IY

4060 NEXT IX

4070 IF(ANS=0) GOTO 4500

4200 C$=STR$(INT(XLOC-8)): R$=STR$(INT(YLOC-3))

4210 LPRINTCHR$(27)+"&a"+R$+"r"+C$+"C";
4220 LPRINT STR$(ABS(H))+SPACE$(7)+STR$(ABS(K))+SPACE$(7)+STR$(ABS(L))

4230 C$=STR$(INT(XLOC-8)) :R$=STR$(INT(YLOC-6))

4240H$= .... :KS= .... :L$= ....

4250 IF(H<0) THEN H$="-"

4260 IF(K<0) THEN KS="-"

4270 IF(L<0) THEN L$="-"

4280 LPRINT CHR$(27)+"&a"+RS+"r"+C$+"C";

4290 LPRINT H$+SPACES(9)+K$+SPACE$(9)+L$

4500 RETURN

5000REM AXIS POINTS DRAW SUBROUTINE

5010 H=A: K=B: L--C: GOSUB 4000

5020 XLOC=950:YLOC=275

5030 H=U: K=V: L=W: GOSUB 4000

5040 XLOC=475:YLOC=465

5050 H=D: K=E: L=F: GOSUB 4000

5500 RETURN

9000 REM EXIT AND "ID" CODE

9010 LPRINT CHR$(27)+"&12D": LPRINT CHR$(27)+"&k10H"

9020 LPRINT CHR$(27)+"&alrlC";

9025 LPRINT "CUBIC PROJECTION ON ";DATES;" AT ";TIMES;" using file ";F$

9030 LPRINT CHR$(27)+"&a2rlC";

9040 LPRINT "(abc)=(";A;",";B;",";C;")";:

9050 LPRINT" (def)=(";D;",";E;",";F;")";:

9060 LPRINT" (uvw)=(";U;",";V;",";W;")";: 9070 GOTO 400

9999 END

99
APPENDIX B:

ASCII File hklalll

-1 -I ,-1 ,0

-1 -I ,0,0

-I -1 , 1 , 0

-1 0,-1 ,0

-1 0,0,0

-1 0,1,0

-1 1 ,-1 ,0

-1 1 ,0,0

-1 1,1,0

0,-I -1 ,0

0,-1 0 0

0,-I I 0

0,0 -I 0

0,0 1 0

0,1 -1 0

0,1 0 0

0,1 I 0

1,-1 0 0

I,-1 1 0

1 0 -1 0

1 0 0 0

1 0 1 0

1 1 -1 0

1 1 0 0

1 1 1 0

0,0,0,0

lOO
STEREOGRAPHIC PROJECTION ANALYSIS OF

FRACTURE PLANE TRACES IN POLISHED SILICON

WAFERS FOR INTEGRATED CIRCUITS

Wayne L. Elban

Department of Electrical Engineering and Engineering Science

Loyola College

4501 North Charles Street

Baltimore, Maryland 21210

Telephone 410-617-2853

101
/

102
STEREOGRAPHICPROJECTIONANALYSISOF FRACTUREPLANE TRACES

IN POLISHEDSILICONWAFERSFOR INTEGRATEDCIRCUITS

Wayne L. Elban

Dept. of Electrical Engineering and Engineering Science

Loyola College, Baltimore, Maryland 21210

ABSTRACT: A procedure is described for crystallographicaUy assessing probable

fracture planes observed in polished wafers used in integrated circuit manufacturing. The

wafers had been sliced from a silicon single crystal grown by the Czochralski method.

To confirm the wafer orientation as provided by the manufacturer, a back-reflection Laue

x-ray diffraction photograph was obtained, and a zone analysis was performed. The

wafers are reasonably fragile and can be broken into large fragments, making the

intersection of the fracture planes with the polished surface suitable for characterization.

A single-trace analysis, involving the use of a standard cubic stereographic projection,

was performed on: (1) a simple (crystallographic-appearing or cleavage) fracture for one

wafer and (2) a more complex fracture (i.e., partially non-crystallographic-appearing with

straight segments) for a second wafer. This allowed the identification of a number of

possible fracture planes from which the most likely were selected by comparison with

what is reported in the literature for silicon. The cleavage fracture in the first wafer and

three straight segments of the complex fracture in the second wafer are consistent with

{111} fracture planes. A two-trace analysis on the wafer with the cleavage fracture

confirmed this plane.

KEY WORDS: crystallography,singlecrystal, back-reflectionLaue x-ray diffraction,

stereographicprojection, trace analysis,fracture, cleavage,silicon.

PREREQUISITE KNOWLEDGE: upper-levelundergraduatelaboratoryexperiment

requiring basic knowledgeof crystallography,x-raydiffraction, and fracturebehavior as

described in an introductorymaterialssciencecourse.

OBJECTIVES:

(a) ExperimentalGoals:

1. to determinethe orientationof a polishedwafer of single crystal silicon

using the back-reflectionLaue x-ray diffractiontechniqueand

103
2. to perform a stereographicprojectionanalysisof fractureplane traces in

silicon wafersto identifyprobablecandidateplanes.

(b) Learning Goals:

1. to become familiarwith a widelyused x-ray diffractionmethodfor

orienting singlecrystals;

2. to become familiarwith stereographicprojectionsand their use in applied

crystallographyproblems;

3. to become familiarwith the appearanceof crystallographicversus noncrystallographicfracture in brittle materials;

4. to become familiar with trace analysis to identify important crystallographic

features in single crystals; and

5. to become familiarwith the materialsscienceliterature in order to extract

relevant crystallographicinformation.

EQUIPMENT AND SUPPLIES: (1) Polished single crystal silicon wafers (100 mm

diameter x 0.54 mm thick); (2) Standard x-ray generator with back-reflection Laue

apparatus providing diffraction photograph; (3) Tracing paper; (4) Greninger chart; (5)

Wulff net; (6) Standard cubic stereographic projections -- (001), (110), and (111).

PROCEDURE:

Introduction

Single-crystal materials are increasingly being adopted in technological

applications. Examples include turbine blades in jet engines and semiconducting

materials in a variety of electronic devices. The ability to orient single crystals and to

identify their crystallographic features are important skills to acquire. The determination

of the orientation of a single crystal is often accomplished using the Laue x-ray

diffraction method in either back-reflection or through-transmission arrangement [1,2].

To analyze the resultant diffraction pattern, a two-dimensional circular plot of threedimensional angular relationships for crystal directions and planes, known as a

stereographic projection [3,4], is used (Instructor Note 1). In this plot, directions and

104
plane poles are representedby points whileplanes appearas great circles. Stereographic

projectionsare also useful in characterizingcrystallographicfeaturessuch as growth

facets, slip bands, growth and deformationtwins, cracks, and etch pit arrays. Relevant

planes/directionsfor such featurescan be identifiedby analyzingtheir traces (i.e., the

intersectionof the plane associatedwith a particularfeature with the as-viewedsurface).

For single crystals of brittlematerials,fractureoften occurs along specific

crystallographicplanes, termed cleavageplanes. Lawnand Wilshaw[5] provide a list of

the primary cleavageplanesfor a numberof materials. Cleavagefracture is identifiedby

the appearanceof straight, crystallographictraces. Fracture in brittle crystals can also be

non-crystallographicor amorphousin characterwith traces that are curved or highly

irregular.

Large (>_ 76 mm diameter) polished single-crystal silicon wafers [6] are used in

considerable quantity in integrated circuit (IC) manufacturing. The wafers are sliced

from an ingot grown by the Czochralski method. A crystallographic reference flat (Fig

6.1, Mayer and Lau [7]) is ground on the ingot prior to slicing. Because of their thinness

and the brittleness of silicon, the wafers are reasonably fragile, and breakage can occur

on handling.

This work consists of performing a back-reflection Laue experiment to substantiate

the orientation of the wafers as given by the manufacturer. A stereographic projection

analysis of fracture plane traces is then performed on wafers that have been broken. The

trace analysis provides a number of candidate planes from which the most probable are

selected on the basis of what has been reported in the literature. In one instance, the

necessary two-trace analysis to confirm the plane was performed (as an option). The

following problem statement is given:

Youhave recentlybeen hired as a materialsscientistby a companythat

manufacturespolishedsingle crystalsiliconwafersfor use as the IC substrate

material. Unfortunately,an unusuallylarge numberof wafershave been breaking.

As a first step in failure analysis, you havebeen askedto identifythe fracture

planes that result. It is of interestto investigatethe fracture that resulted in two

wafers:

(1) the simplefracture in Wafer#1; and

(2) the more complexfracture in Wafer #2.

105
A. BACK-REFLECTION LAUE EXPERIMENT (Instructor Note 2)

1. Mount the entirewafer or a portion containingthe reference flat on a goniometer

(Instructor Note 3). The orientationof the wafer must be noted (instructorNote

4).

2. Obtaina Laue photograph(instructorNote 5).

Data Analysis

1. Study the shapeof the diffractionspotsrecordedon the film [8-9]. Sharp,

circular spotsindicategood perfectionin the small volumeof the crystal that was

sampled. Streakedspots(i.e., spotswith asterism)reveal that the crystal is

strained.

2. Since the photographwas taken in back-reflection,it must be read throughits

back to relateproperly to the as-viewedwafersurfacewhose orien_tion was

previously noted. The film readingcan be accomplishedby pressing a needle into

the center of the spotsto be analyzedand then markingeach spot on the film back

with a black felt tip marker. Transferthe spotsto tracing paper by placing it on

top of the back of the film while lightlydenotingthe outline of the film with its

top being up.

3. For six (6) prominent zones of spots, measure the angle of inclination, if, and the

azimuthal angle, o_,using a Greninger chart and following in detail the procedure

described by Barrett and Massalski [10].

4. Using a Wulff net and again referring to the procedure in Barrett and Massalski,

plot the zone axes on a stereographicprojectionpaper. This can be accomplished

by imposingthe axes on the sametracing paper containingthe previouslyrecorded

Laue spots. In this case, care must be taken to ensure that the centers of the Laue

photograph and stereographicprojectioncoincide.

5. The crystal surface incident to the x-ray beam is identified by comparing the

positions of the zone axes with the locations of directions denoted in the various

computer-generated [11] standard cubic stereographic projections provided (i.e.,

(001), (110), and (111)) -- (Instructor Note 6). Close coincidence for all six (6)

axes must occur to establish the identity of the irradiated surface (Instructor Note 7).

106
B. IDENTIFICATIONOF PROBABLEFRACTUREPLANES

1. Trace the outlinesfor the fragmentsof the two wafers provided (InstructorNote

8).

2. Examinethe perimeterof the wafer fragments. Distinguishthose portionsthat are

curved or irregular from straight-linesegments. The exterior growth surfaceof

the crystal is curved and non-crystallographicfractureyields curved or irregular

traces. The straight-line(i.e., crystallographic)traces result from the intersection

of either a fracture planeor the referenceflat with the as-viewedpolished surface.

Referring to the proceduredescribedby Barrett and Massalski[12], extend those

crystallographic-appearingfracture and referencefiat traces using a thin lead

pencil and straight edge suchas drafting triangle. Measurethe angle between

each fracture trace and the referenceflat trace for each wafer using a protractor.

Data Analysis

1. For the wafer fragments,label at least two (2) instancesof non-crystallographic

fracture if it occurred.

2. Impose each crystallographic fracture plane trace, correctly oriented, on a separate

appropriate (Instructor Note 9) standard stereographic projection using the

corresponding angular measurement relative to the reference flat trace.

3. Constructa diametralline that is orthogonalto each fractureplane trace. The

constructedline shouldintersect or be in close proximityto a number of Miller

indicesthat appear on the standardprojection. Anyof theseindicesthen are for

poles of planes(i.e., plane normals)that couldexplain the observedfracture. The

field of candidatescan be immediatelyreduced,roughlyin half, by visually

determiningthe inclinationof the fractureplane and discardingthose poles on the

side of the projectionthat are not appropriate.

4. Refer to fractureplane observationsreported in the literature [5,13-16] to

determine whetherany of the other remainingplane poles are consistent.

5. Optional Activity: Obtaina photomicrographof the endview of the fracture

plane and perform a secondtrace analysisto determinethe exact identityof the

plane in question,thus eliminatingthe other remainingcandidates.

107
SAMPLE PLOTS AND DATA SHEETS: All of the experimental steps were performed

twice to verify that the results were reproducible.

Laue Spot Appearance: All of the spotswere circular and withoutany evidenceof

asterism.

Wafer Orientation: A schematic of the Laue photograph for Wafer #2 that was analyzed

appears in Figure 1 imposed on a (111) stereographic projection in which the orthogonal

[121] and [101] directions are shown. Six (6) prominent zones and corresponding axes

are identified, including [101] (Zone A). The measured 4_,o_angles allowing the zone

axes to be plotted are given in Table I. The polished surface was identified to be

approximately 4° off (111) as directly viewed. Rotating the stereographic projection this

angular amount about the +[101] direction provided a nearly exact match with the

standard cubic (111) stereographic projection. This result is in perfect agreement with

the crystallographic information provided by the manufacturer.

Non-CrystallographicFracture and CrystallographicFracture Plane Traces: The outlines

of the fragmentsof Wafers#1 and 2 are givenin Figures 2 and 3, respectively.

Althoughnot present in Wafer#1, examplesof non-crystallographicfracture did occur in

Wafer #2. The traces of fractureplanesthat appearedto be crystallographicare denoted

in both figures. Includedare the measuredanglesbetweenthe fractureplane traces and

the reference fiat trace. The crystallographicfractureplane traces and their orthogonal

constructionsappear in a seriesof standardcubic (111)stereographicprojections(Figures

4-6). Traces 2 and 5 were not analyzedsincethey are the sameas Trace 1 (Figure 4).

Fracture Plane Candidatesand LiteratureComparison:-Referringto Figures 4-6, those

plane poles with low indices(h, k, and 1 < 131)that are intersected (either exactlyor

nearly) by the orthogonalconstructionsare listed in Table II. The poles are divided

based on the inclinationof their planesto the polishedwafersurface, and the impossible

poles are noted and eliminatedfrom consideration. The single-traceanalysisresults are

consistent with the well-knownobservation(e.g., References[5] and [13]) of {111}as

the primary fractureplanesfor silicon. However, the results are unableto distinguish

between {110}fracture that has also been reported [13-16]. As such, a two-trace analysis

is necessaryto resolvewhich plane is involvedin the wafers used in this study.

SecondTrace Analysis: A photomicrographshowingan end view of the cleavage

fracture plane in Wafer #1 appearsin Figure 7. The angle between this plane and the

polished near (111) planewas measuredto be 73°. Placing (Figure 8) this fracture plane

108
Top @C

I F [lil]

A [iOl]z

B [lio]z !

(lll)

I/off A

D [l_flz

E [1_2]Z

C {OTqz /

I

Near[fill

O Position When Rotated 4° About + [ T01 ] Axis

Near (111)

Figure 1. Back-reflection Laue photograph in combination with stereographic

projection showing zones of diffraction spots and zone axes to identify the near

( 111) polished surface of Wafer #2 as directly viewed.

109
Table I. MeasuredAngularInformationfor ProminentZonesin Back-ReflectionLaue

Photograph of Wafer #2 (Figure 1)

Zone Angle of Inclination (_b) Azimuthal Angle (o0

A 0° 90° CCW*

B 4° 149° CCW*

C 4° 210° CCW*

D 4° 180° CCW*

E 4+0 190° CCW*

F 23+0 180° CCW*

*CCW = counterclockwise.

Table II. CandidateFracture Planes Obtainedfrom SingleTrace Analyses(Figures 4-6)

Trace PossiblePlanes EliminatedPlanes

1, 2, & 5 (233) (122) (133) (322) (219 (311)

(911)(T33) (T22) (100) (311) (211)

(233) (111) (322)

(211)

3 & 6 (323) (212) (313) (232) (129 (131_)

(101) (313) (212) (010) (131) (121)

(3_23)(1i"1)(232)

(121)

4 (332) (221) (331) (223) (112) (113)

(110) (331) (221) (001) (113) (112)

(332_)(liT) (223)

(112)

110
Near

[:::]

I

/

I

/

/ 31.5°1

/ I

I

Reference Flat

Near (i 11)

Trace 1 Polished Surface

/

10nun

b----t

Figure 2. Wafer #1 fragment exhibiting cleavage fracture

with associated Trace 1.

111
Near

t

I 32.5° /

/

/I

,2| o

Examples of /

/

Trace 4 Non-crystallographic /

\ Fracture / I /

Trace 6 \ / -If-- --

\ /I

\ /

\ / Reference Flat

\ /

Trace 3 -¥

/

/ Near (111)

/ / Polished Surface

/ /

/ /

/ /

\

/ /

Trace 2 \

/ \

/ \ Trace 5

\

\

10mm I d_X

/

b-----t _3_o \

I

Figure 3. Wafer #2 fi'agments exhibiting both cleavage fiacture with

associated Traces 2-6 and non-crystallographic fi'acture.

112
2_;1 . . • 4- • • i_€

,o oD oo ° ° " °oH Oo

...." ""..... . Trace 1

_.-" 2,_2 ._.....

lr" 3il

• i 2_.1 122 113

• • t 332 2_3 a

" Iji 0_3 "'. •" 3io 3_1 _3 / o_3 4_3

32_ " ' / o_2 _"

• m 3_2 2_3

"o

Candidate Plane ' 3,_3 ' '_2 / , ..

_zt4 Poles Along si2 ' 2i3 _i3 oi_ ,

• 3i{ This Line , 3_3 , ' _s ..

23

3j} .^o 201 302 101 203 102 103

__ ,3Ul l l I II l

l , I

,,oo / ool

• | o

,o, / ,o, zo_ ' 312 3,13 21 ' _oz " • _311 m 212 ,m 113 m

m m m 3_03 .

30;5 m "',.211 323 / 112 0t3 m

l 3JO 1.,,,,,322 i /223 m I

t / I

50{ 31i 210 321 _111 123 012 _113 ;,Or l l l II l l |

332/m_3 m 32o 221,/ .,22 023 _,3

• 31;;| 21t i 32{ ' 311" /2152 _3 ' 123 112| |

• 3j_ , 1jo 2_31121 132 "',,_1 , _,13 •

21_ 32_ - 7 ' ' _33 213 _12 : • I ,22{ 3m31 230 131 o_ "_'_ 2 _23' "

32:3, 33;, _' . " 120/ ' 02? . _,_3 , _12

;_1_ ..: 231 , i' _m32 "_/;,,'% ,

' ';' ' / 11o o31 ' _"_-I •

22_ 2,_212i / 121 " "-q,-- •

"I_ , , /, ojo

-__. 221 • _'

• 1_ 1_ 2_, , ..'"

"_2_ 133 / 031 _3o b}l _,za"

• l / l l • ,

.. / o_{ i2o ."

"... / o?_" ' _?o .."

•. /. _I_

"qZ' ?jo-"

"'"'"-._Z _ _i _3_..-'" • o o ,.|o "

Figure 4. Standardcubic (111) stereographicprojection showing

Trace 1 and corresponding candidate fracture plane poles.

113
Candidate Plane Poles 

I /Along This Line 

Figure 5. Standard cubic (1 11) stereographic projection showing 

Traces 3 and 6 and corresponding candidate fracture plane poles. 
Figure 6. Standardcubic (111) stereographic projectionshowing

Trace 4 and corresponding candidate fracture plane poles.

115
Figure 7. Photomicrograph of end view of Wafer #1 showing

cleavage fracture with associated Trace 7.

116
A []01] Z

B [fi'o]z

(111)

[Tol]A

D [l_l]z

E [1_2]z

C [O_l] (ill)

F [ITI] Z /

from

Trace 7

I

[T2[]

Near[fffl

O Position When Rotated 4°About + [ ]'01 ] Axis

Near (111)

Figure 8. Trace 1 together with Trace 7 angle plotted on Figure 1 to

identify (] 11) cleavage fracture in Wafer #1.

117
trace on the stereographicprojectionappearingin Figure 1 and performing the necessary

4° rotationabout the _.+[_01]axis allowedthe fractureplane to be identifiedas (]'11).

INSTRUCTOR NOTES:

1. Stereographicprojectionsand their applicationsare discussedin considerabledetailby

Johari and Thomas [17]. A numberof very nice workedexamplesinvolving

stereographicprojectionsare presentedby Moon [18].

2. If it is not possibleto perform the Laue experiment,orientationinformationprovided

by the manufacturercan be relied upon, allowingthe trace-analysisportion of the

experimentto be performed still.

3. A small(1 cm x 1cm) pieceof double-sidedtape (3M Scotchbrand) was used to

attach the wafer firmly to the goniometerand preserve the necessaryorthogonality

conditionfor the incidentsurfaceof the waferand x-raybeam. The wafershould

subsequentlybe removedas soon as is practicalto lessendetachmentdifficultythat can

lead to unwantedbreaka,ge.

4. In this work, the polishedside of the wafer was as-viewedwith the reference flat on

the fight, and care was taken to align the flat vertically.

5. SAFETY PRECAUTION: Consideration should be given to obtaining the Laue

photograph for the students ahead of time and simply showing the experimental setup and explaining how the photograph was taken. Using a copper x-ray tube, a high

quality photograph resulted with Polaroid Type 57 film (positioned 3 cm from the wafer)

when the generator was operated at 30 kV and 20 ma for an exposure time of 7.5 min.

The time was sufficiently short that fluorescence was not a problem.

6. Seecompanionpaper[11]in thisWorkshopfor availabilityofstandardcubic

stereographicprojections.

7. The agreementbetweenthe plottedzone axes and thebest candidatestandard

projection (i.e., (111)in this experiment)will be reasonablyclose but still only

approximatesince the waferswere intentionallysliced3.5 to 4.5° off of (111) by the

manufacturer.

118
8. The fragmentswere obtainedby fracturingas-receivedwholewafersin cantilever

flexure by hand. Care wastaken to align the wafer in the hand-heldclamp so that the

desired {111}fractureoccurredpreferentially. SAFETYPRECAUTION: It is required

that gogglesbe worn while wafers are being flexed to avoid the danger of flying

fragments! It is suggestedthat 75 mmdiameterwafers be tried as they are much thinner

and hence easier to fracture.

9. Since the surface incidentto the x-ray beamwas determinedto be approximately4°

from (111), the standard(111) projectionis adequate.

REFERENCES:

[1] Barrett, C.; and Massalski,T.B.: Structureof MetalsCrystallographicMethods,

Principlesand Data, ThirdRevisedEdition.PergamonPress, 1980, pp. 90-96.

[2] Cullity, B.D.: Elementsof X-rayDiffraction, SecondEdition. Addison-Wesley

PublishingCompany,Inc., 1987,pp. 149-160.

[3] Barrett, C.; and Massalski, T.B.: _, pp. 30-50.

[4] Cullity, B.D.: _, pp. 63-78.

[5] Lawn, B.R.; and WilshawT.R." Fracture of BrittleSolids. CambridgeUniversity

Press, 1975, p. 17.

[6] "Silicon in Electronics," Excerpt from KEYNOTES '91-92. MEMC Electronic

Materials, Inc., 501 Pearl Drive (City of O'Fallon), P.O. Box 8, St. Peters,

Missouri 63376.

[7] Mayer, J.W.; and Lau, S.S.: ElectronicMaterialsScience:For IntegratedCircuits

in Si and GaAs. MacmillanPublishingCompany, 1990, p. 143.

[8] Barrett, C.; and Massalski, T.B.: _, pp. 92-95.

[9] Cullity, B.D.: _, pp. 158-160 and 260-265.

[10] Barrett, C.; and Massalski, T.B.: _, pp. 211-222.

119
[11] Coyne, P.J., Jr.; Kohne, G.S.; and Elban, W.L.: PC Laser Printer-Generated

Cubic StereographicProjectionswith AccompanyingStudentExercise, National

Educators' Workshop:Update94, NASACP- , 1994.

[12] Barrett, C.; and Massalski, T.B.: _, pp. 44-47.

[13] Misra, A.; and Finnie, I.: On the Scribingand SubsequentFracturing of Silicon

SemiconductorWafers.J. Mater. Sci., vol. 14, no. 11, November 1979, pp.

2567-2574.

[14] Kaufman, M.J.; and Forty, A.J.: A Detailed Fractographic Analysis of Cleavage

Steps in Silicon. J. Mater. Sci., vol. 21, no. 9, September 1986, pp. 3167-3172.

[15] Tsal, Y.L.; and Mecholsky, J.J., Jr.: Fractal Fracture of Single Crystal Silicon. J.

Mater. Res., vol. 6, no. 6, June 1991, pp. 1248-1263.

[16] Tsai, Y.L.; and Mecholsky,J.J., Jr.: Fracture MechanicsDescriptionof Fracture

Mirror Formation in SingleCrystals.Int. J. Fract., vol. 57, no. 2, September 15,

1992, pp. 167-182.

[17] Johari, O; and Thomas, G.: The Stereographic Projection and Its Applications.

Techniques of Metals Research Volume IIA, Interscience Publishers, 1969.

[18] Moon, J.R.: Worked Examples in Stereographic Projection. Monograph No. 2,

The Institution of Metallurgists, 1978.

SOURCES OF SUPPLIES (1994 Prices): Polished single crystal silicon wafers in

several diameters are available from MEMC Electronic Materials, Inc., 128 Corporate

Center, 70 Blanchard Road, Burlington MA 01803. The cost is nominally $12.00-15.00

each for 100 mm wafers. The Greninger chart and Wulff net, both plastic, are available

from Polycrystal Book Service, P.O. Box 3439, Dayton, OH 45401-3439 at a cost of

$20.00 each. Various standard cubic projections (18 cm diameter) can also be purchased

from Polycrystal for $15.00 each.

ACKNOWLEDGEMENTS: The author is deeply indebted to D.W. Sloat, MEMC

Electronic Materials, Inc., for providing the polished silicon wafers with crystallographic

information that allowed the current work to be accomplished. The help of D.S.

Richards, Dept. of Electrical Engineering and Engineering Science, Loyola College, in

120
using computergraphicsto generateFigures 1-3 and 8 is gratefullyrecognized. Special

thanksto R.D. Eastman, Dept. of ComputerScience,Loyola College, for using image

processingsoftware to obtainFigure 7 in its final form. It is highly unlikelythat this

work wouldhave been performedhad not R.W. Armstrong,Dept. of Mechanical

Engineering, Universityof Maryland, CollegePark, masterfullydemonstratedthe use of

stereographicprojectionsto the authorto solve a variety of applied crystallography

problems.

121

PAPER CLIP FATIGUE BEND TEST

Alan K. Karplus

Mechanical Engineering, School of Engineering

Western New England College

1215 Wilbraham Road

Springfield, Massachusetts 01119-2684

Telephone 413-782-1220

123
124
Paper Clip Fatigue Bend Test

Alan K. Karplus

Department of Mechanical Engineering

Western New England College

Springfield, MA 01119-2684

KEYWORDS: Fatigue Test, Wire, Paper Clips

PREREQUISITE tGgOWLEDGE:

The student should be familiar with different types of paper clipsand may be aware that paper clips can

be made of materials other than steel wire. The student is most likely familiar with the fact that a paper

clip can be broken or fatigued by bending it back and forth, too.

OBJECTIVES:

Fatigue tests are performed to determine the effect of different bend angles on the response of a

materialto cyclic loading.A thin wire rod, such as found on the straight leg of a regular size paper clip,

is selected and cut to three-quarters of one inch long. Each rod is then held and cycled through a

bend angle of a specified size until the rod fails. This processis repeated three times for a specified bend

angle. The average number of cyclesto failure for three samples is then calculated and plotted on a

graph. To show how the number of cycles changes as the angle of bend changes four different bend

angles are used. Next the sequence is repeated for a differentsize paper clip and the findings compared

to illustrate the wire size effect and the impact of the fatigue attribute of paper clip wire.

EQUIPMENT AND SUPPLIES:

1. Paper Clips. Regularsize or Associated Paper clips No.1 (H4-02001) and Jumbo, Associated Paper

Clips, Jumbo (H4-2002)

2. Protractor made with an 8 1/2 in. by 11 in. piece of paper, and a plastic protector page

3. Diagonal Cutting Pliers

4. Two pairs of regular Pliers or Homemade wire sample holders

5. Safety Glasses

5. Gloves

7. Wire gage measure or Vernier Caliper

8. Data Sheet see below for the format

PROCEDURE:

l'he firststep is the creation of handmade symmetricpaperprotractor with total angles of 45, 90, 135 and

180 degrees designated on the paper. This protractor is desig-nedso that a total angle will be half of its

:tepee displacement to the left and the other half to the rightof the centralposition of the starting position

tbr a test. A full cycle is a left off-set followed by a center pass through to a right off-set and return to the

:enter.

l'hesecond stepistomakefourtrials,eachat a differentbend testangle.Atrialisthe processingof three

125
samples at a selected bend angle. This means that for each bend test angle, three samples are made, cycled

to failure, the number of cycles to failure recorded and the average number of cycles tallied. After the first

trial the three remaining test angles are to be processed, and then prepare a graph with labeled axes of the

test angle on the vertical axis against the number of cycles to failure on the horizontal axis. The line on the

plot should be labeled "Regular". The plot should be titled "Fatigue Bend Test for Paper Clips", and you

should add where the work was done, your name and the date.

The third step is the selection of a second size of wire such as that found in a jumbo paper clip and making

trials. Again, four trials, each with three samples and the determination of an average number of cycles to

failure for each of the four test angles listed above, is required. The findings are plotted on the same graph

as for the regular size paper clip and labeled "Jumbo". A comparison between the jumbo and regular paper

clip test results can show the impact of size on the 'fatigue curve'.

PA_PER PROTRACTOR:

To make a Paper Protractor secure an 8.5 by 11 inch sheet of paper and fold it in half parallel to the

long length. Select one narrow end of the tblded sheet and fold back the end until the short end

coincides with the long fold line to obtain a 45 degree angle. Repeat this tblding with the 45 degree

folded portion of the sheet so a 22.5 degree angle is obtained. Repeat the tblding sequence for the other

half of the sheet. Unfold the sheet and draw a dark line to specify, and dimension the 45, 90, 135, and

180 degree included angles that are symmetric to the long 11 inch fold line. Darken the longest fold

line on the protractor as this line should be in line with the extended part of the fastener when a test is

run.

Hint: Place a clear plastic protector page (an overhead transparency is suggested) over the Paper

Protractor and use masking tape around the edge to secure the clear cover page to the protractor page.

SAMPLE PREPAR.ATION:

Secure several regular sized paper clips and prepare a dozen rod pieces each three-quarters of an inch

long by cutting the semi-circular loop ends from the paper clips. This process is to be repeated for the

Jumbo paper clip, too.

TEST ACTIVITY, DATA AVERAGING AND GRAPHING:

Tests are to be performed to determine the effect of size of bend angle on the fatigue behavior of a

material. This first set of trials is for the regular paper clips.

The initial step for trial one is to select the rod, grip each end of the rod in the jaws of a pair of pliers

being sure the rod is fully inserted 1/4 inch into the jaws. Next place the nose of one pair of the pliers

with the sample extending over the protractor with the plastic protection page at the vertex of the

protractor and in line with the center line of the protractor. There should be a 3/8 inch long open len_h

that covers the protractor, and in which the bending can occur. The second pair of pliers will be on top of

the plastic protection page.

When the 45 degree test angle is chosen, the cycle of bending starts at the center line, moves to the left,

moves to the right passing the center line, and returns to the centeral position. Count this as one

complete cycle. This cycle is repeated until the saample fails at which time the number of full and

partial cycles are counted and recorded in the data sheet show in Table 1. Several practice _xlrl_are

126
recommended tO develop skill in holding each end of the rod securely while bending the rod.

Please fasten the protractor onto a surface with masking tape and then hold one end of the rod at the

origin on the protractor and move the pliers back and forth within the appropriate bend angle lines.

Remember when you start bending that the axis ot"the rod should be in line with the centertine of the

protractor. For each bend angle three samples are used, loaded to failure, and the number of cycles for

each sample to fail recorded, and the average number of cycles to failure tallied. This completes trial

one.

For larger rods the use of a prefabricated holder instead of pliers is recommended. See the Appendix for

specifications. THE EXPERIMENTER SHOULD TAKE CARE TO WEAR SAFETY GLASSES and

to carefully watch the rod to discern the first site on the rod where failure starts. The region will

discolor,change in geometry, and fracture. Sometimes the experimenter can feet a change in the

resistance offered while bending, too.

Trials two through tour follow the same sequence, except that the angle is changed to 90 degrees, to 135

and to 180 degrees. Prepare a graph of the bend angle on the vertical axis against the number of cycles

to failure on the horizontal axis. Be sure to label the axes with a name and scale. Each point placed on

the graph should be placed on the plot and circled by a symbol that surrounds the data point. Connect

the symbols on the graph sequentially from high to low by using the data points to 'line-up' the data

points, but drawing a line ONLY between the symbols. This process lets the data points be clearly seen.

Be sure to label the line "Regular" for the regular paper clip. To complete the gaph add on the title

"FatigueBend Test for Paper Clips", the place where you did the testing, your name, and the date.

Table 1.Regular Paper Clip Data Table

Regular Paper Clip

Bend Angle 45 90 135 180

Trials Cycles Cycles Cycles Cycles

Sample 1

Sample 2

Sample 3

Total

Average

Run a second set of trials for the jumbo paper clip rods repeating the same four trials used for the

regular paper clip wire rods. This includes making three sample runs at a specified bend angle,

averaging the data to place in Table 2, below and adding the results to the graph. The label "Jumbo"

should be attached to the curve drawn by connecting the 'Jumbo average points symbols" with a series

of sequential lines. The symbol could be a triangle with the data point inside.

127
Table 2. Jumbo Paper Clip Data Table

Jumbo Paper Clip

Bend Angle 45 90 135 180

Trials Cycles Cycles Cycles Cycles

Sample 1

Sample 2

Sample 3

Total

Average

A comparison between the jumbo and regular paper clip can show the impact of size on the 'fatigue curve'.

Features to notice include how rapidly the curve 'fails' as the size to the total angle changes. Remember

that the size of the bend angle represents the amount of mechanical straining introduced by the

experimenter.The larger paper clip mig3athave a curve that is below the 'regular' paper clip because it is

larger in diameter and less ductile or bendable.

COM-MENTS:

There are many oppommitiesthat can be developed fromthis basic exercise.

1. For example a paper fastener usually made of brass can be used instead of the paper clip. !'nthis case

two sizes of paper fastener can to be studied: Brass Round Head Fasteners No. 6 and No. 4. Two

experiments are to be made. The first is for the No. 6 Paper Fastener. Three samples at each of four bend

angles are to be evaluated for experiment one. Follow the same procedure outline for the paper clips

with recommended angles of bend of: 45, 90, 135, and 180 degrees. This time align the centerline of the

protractor with respect to an axis in which the paper fastener is mounted. It may be helpful to usejust

the paper protractor without the plastic cover page mounted with masking tape.

To mount the paper fastener in a parallel jaw clamp or a vise, separate the legs of the fastener and secure

the free end of one leg in the clamp mid-way along its leng_.h.Take the extended portion of the paper

fastener between your fingers and bend the fastener back and forth perpendicular to the width of the leg

through either a 180, 135, 90, or 45 degree angle, counting the number of complete bend cycles to

failure. Record this value in the data table. Complete the remaining trials. Each trial has three tests for a

bend angle, an average value calculated for the number of cyclesto failure as shown in the table, and a

plot of the average values on a graph against the total bend angle. Be sure to label the curve, the axes,

the graph with a title, where the work was done, your name and date.

The second experiment is for the No. 4 Paper Fastener. Be sure to place the findings from Paper

Fastener No. 6 with a labeled curve on the same _aph as for Paper Fastener No. 6. To help size the

bend angle a Paper Protractor as presented above, can be made. Also, to save Paper Fasteners and

128
use all available legs, the second leg of the fastener can be used for the next test to reduce the number of

fasteners destroyed.

2. A comparison between the jumbo and regular paper clip can show the impact of size on the 'fatigue

curve'. The same is true for the Paper Fastener. Additional experiments with different materialssuch as

rod samples of aluminum, brass, welding rods, etc., and some plastics can add depth of understanding as

well as provide interesting contrasts on a plot of results. In all cases the material and diameter of the rod

should be noted on the gaph. For the future different types of (heat) treating of the rods can be considered

as well as changing the surface condition by abrading with emery clothes of various grits or even adding a

notch. The latter case provides tbr the calculation of a notch sensitivity ratio when a base test is for an unnotched rod..Amothervariation is the cleaning of the surface of the rods with different mediums such as

acetone, oil, blueing, and other operatives, and each time creatingsensivitity ratios to a 'base' rod condition.

3. To assist the reader and give confidence in the performanceof Fatigue Bend Tests the tbllowing data is

supplied. First, an aluminum CX WELD NO. 23 fillerrod (diameter 0.125 inches) was used, and second, a

gas welding bronze colored steel filler rod ( diameter 0.091 inches) was tested. Figure 1 show the

graphical comparison.

Table 3. Aluminum Filler Rod Data

Aluminum Filler Rod: CX WELD NO. 23

Bend Angle 45 [ 90 135 180

Trials Cycles Cycles Cycles Cycles

Sample 1 8 3.5 2 .75

Sample 2 8 3.5 1 .50

Sample 3 7.5 2.5 1.5 .50

Total 23.5 9.5 4.5 1.75

Average 7.8 3.2 1.5 .6

Table 4. Steel Filler Rod Data

Bronze Colored Steel: Welding Filler Rod

Bend Angle 45 90 135 180

Trials Cycles Cycles Cycles Cycles

Sample 1 38 7.5 4.5 2.75

Sample 2 37 8 4.75 3.25

Sample 3 43 8 4.75 2.75

Total 118 21.5 14.0 8.75

Average 39.3 7.2 4.7 2.9

129
Figure 1. Sample Fatigue Curve (Data from Tables 3 and 4)

4. The use of holders is best for wire rods that have diameters for which tooling to make the holes in the

ends of the holders, exists. Diameters smaller than 0.040 inches is often a machine shop limit. If the hole

prepared is larger than appropriate, the wire can 'flip around', easily come out of the holder(s), and not

bend. This offers the opportunity to experiment with longer and shorter than 3/4 of an inch rods to

learn the best ways to hold a rod to be bent.

APPENDIX: Holders

A rod sample holding tool set can be prepared by seccuring a pair of rods such as 3/8 inch diameter

round, square, or hexagonal cross-section stock each five inches long.Next machine a hole of the proper

diameter (check the rod size to be tested) with a 0.001 to 0.002 inch clearance one quarter to one- half

inch deep in one end of each of the holders. Consider facing the end first to have a clean surface on the

holders. Remember the wires under test must be long enough to clear the holders in the 180 degree

bends ( two half inch deep holes plus 3/4 inch bend region needs a one and three-quarters inch long bend

sample). Also recall that diameters larger than 0.040 inches are available as drill sizes so that another

approach may be best for smaller wire rods. Regular pliers and even vise grips can be considered.

130
ALAN K. KAI_LUS

Alan K. Karplus is Professor of Mechanical

Engineering at WesternNew England

College, Springfield,Massachusetts. He has a

Bachelor's degree fromTufts College, a

Master'sdegree fromIowa StateUniversity

and a Ph.D. from Colorado StateUniversity.

He has been involved with the freshman

engineering program, coordinatesthe junior

and seniormechanical engineering laboratory

program,teaches Materials Science and

supervises M.E. SeniorProjects. He is a

member of ASME, ASEE and ASM

International.

131

MATHEMATICS FOR ENGINEERING MATERIALS

TECHNOLOGY EXPERIMENTS AND

PROBLEM SOLVING

Thomas F. Kilduff

Division of Engineering Technologies

Thomas Nelson Community College

Hampton, Virginia 23366

Telephone 804-851-0272

and

\

James A. Jacobs

School of Technology

Norfolk State University

Norfolk, Virginia 23504

Telephone 804-683-8109

133
134
Mathematics for Engineering Materials Technology

Experiments and Problem Solving

Thomas F. Kilduff

Division of Engineering Technologies

Thomas Nelson Community College

Hampton, VA 23366

James A. Jacobs

School of Technology

Norfolk State University

Norfolk, VA 23504

t

KEY WORDS: Analysis, unit conversions, SI Units and U.S. Customary Units

PREREQUISITE KNOWLEDGE: Often students enter the first course in engineering

materials technology with only basic algebra.

OBJECTIVES: To develop skill and confidence in applying mathematics to solving

problems in engineering materials technology.

EQUIPMENT AND SUPPLIES:

Overhead projector calculator

Microcomputer

RATIONALE: Mathematics, when used wisely, can be a great asset in the study of

engineering materials. This sentence defines the objective of this presentation to remind

instructors to encourage their students to exercise this skill at every opportunity. All of us

recognize that one cardinal principle of good teaching is to allow students to engage in hands-on

activities as part of their learning. Not too long ago books dealing with engineering materials

technology would include a statement such as: 'It is assumed that students have an adequate

background in mathematics, physics, and chemistry for the level of treatment presented.' Is this

statement an adequate description of the students coming into your classrooms today?

In spite of the general poor mathematical preparation of many of our students, it is doubly

important to give them the opportunity, wherever possible, to use their limited knowledge of

mathematics in their study of materials. In so doing they may experience, for the first time, how

mathematics can be an excellent tool to use outside the math classroom in other studies. Second,

if properly used, it can assist them in assimilating and mastering the principles of materials

education.

135
Numerous examples throughout the study of materials can be found to provide .students the

experience, through mathematical calculation, to 1) determine, 2) predict, 3) estimate, and 4)

analyze physical quantities. In this regard we must be sensitive to the requirement that students

develop the habit of producing neat, accurate, and clearly written solutions to assigned problems.

In that regard a statement of what the problem is and what is known about the problem, as well

as a proper identification of the final solution WITH THE CORRECT UNITS INDICATED is

part of the documentation.

ANALYSIS

Analysis, being a mental process, requires a database of knowledge along with the ability to

apply that knowledge. Just as one cannot solve a cross word puzzle without a knowledge of

words, so one cannot analyze a materials problem without a knowledge of materials and

mathematics. This knowledge must be augmented by experience with the tools associated with

these disciplines. The language of both engineering science and technology is mathematics. To

express in words how, for example, forces acting on a material are related to each other, is

difficult to describe with words alone but in mathematical terms this relationship can be

expressed simply and easily.

In our just revised book, Engineering Materials Technology, Jim Jacobs and I have not assumed

students bring to their class a strong mathematical background. We have tried to provide

numerous aids in the book and instructor's manual that offer one stop shopping for problem

solving, thereby enhancing the ease of understanding engineering materials with its associated

mathematics. In the design of the book, we have made great use of work generated by you and

our colleagues form previous NEW:Updates. The many experiments from NEW:Updates provide

excellent opportunities for hands-on activates that help to make concrete demonstrations of

important analysis techniques.

CONVERSION OF UNITS

In spite of repeated efforts to establish the world-wide system of units of measure known as SI

(Internationale Systeme d'Unites) in the U.S. as the one and only legal system, the dual system

of units that includes the U.S. Customary system still is practiced in many areas. Consequently,

the conversion of units is still a necessary technique that must be practiced to perfection. In

addition it is imperative that students of materials must realize the importance of substituting

units as well as numbers into their formulas and other calculations in order to communicate

effectively the results of their analyses in both systems of measure. Note this type of substitution

in the illustrative problem below dealing with thermal conductivity.

We've devoted a segment of our Appendix to discussion of SI/US Customary Units and

Conversions and included tables such as Names and Symbols of SI Units which lists most of the

common derived units, a table with special names for some of these derived units.

136
|llustratlve l'rohlcnl

All illSLllatilign|aterial placedinsidt:Ih¢ walls o1a h(nne is 6 ill. Illick. Tilt: heatflow is

calculatedto bt:4.2 Lltu/hr when the ill.':,iLle tenll)craturc is 7(J°l ;' and the outside [ell|l)erature

iS O°F. Deterllline the thermal o.)tlduclivity of the insulating ii|aterial as the heal Ilow passes

through I ft2of the wall. In addition to expressing k in units of Btu/(hr • ft • °F), convert

your units to SI units using watts, meters, and Kelvin tcmDcrature.

Solution

q Ad

A At

1 ft\" hr 70°g

= 0.03Blu/(hr•ft'°F)

Usingconversion(TableA-7),we have

! Lltu/f•!hr •oF = I.'/29W/m •K

11.03Btu /1i"hr.°F 1.729W\

= 0.052 W/m • K

lnch|ded in this special appendix on the SI system are some thirteen Rules for Usage of these

units as seen on the next page. One example of an illustrative problem dealing with a

computation of a tensile load and using the SI system of units is shown below. Again, it is

stressed that this would be an unnecessaryexercise if the US followed the rest of the world, with

possibly one exception, and converted to the SI system of units in toto. Remember those

wonderful fraction problems such as 3 5/8 + 2/3 = ? Wouldn't it be nice to avoid them?

Problem I

(;iron: A metal rod under tensile load of 356 kN is allowed to withstand a unitstress of Il0

NM/m'.

R_'quired: I:iml tile dialnClcr of lilt: rod in inilliuleters.

SollJllon

I. Ct)nvcrt SI prelixes to powers of 10:

356 kN = 356 x IO'N

IIOMN/m 2 = II0 x I&NIm 2

2. IJ_,eIhe direct stress ft)rnlnla (s = PIA) and solve for the area (A):

P 356 x lip N

A .... 3.24 x 10-j m_

s II0 x I()_N/m _

D = ,/_(3.24 4 x 10-_m 2)

ilr

D = (3.24 x 10'j m_)

132.4 x I114ill]

= 6.429 x 10 2m

= 64.29 x 10 ' m = 64.3 mm (rounding up and using three significant digits)

137
Rules for usage. For standardized usage, the following rules should be observed:

1. Uppercase (capitals) and lowercase letters are never interchanged: kg, not KG.

2. The same symbol is used for plurals: N, not Ns; 14 metcrs or 14 m.

3. No space is left between the prefix and its unit symbol: Gtlz, not G tlz.

4. To form products, a raised dot is preferred (or a dot on a line): kN • m, or kN.m.

The dot may be dispensed with if confusion is not created by its absence.

5. To form quotients, one solidus (an oblique line), a fraction line (horizontal), or a

m

negative power is used to express derived units: m/s, --, or m • s-i S

Note: The solidus illtist not be rel)Calod on the S:iliie line" ili/S", not ill/Sis. Also,

kgl(m • s),_,kg or kg • m__• s-_, but not kg/m/s. Note also tile use of tile m • s

parentheses to avoid ambiguity.

6. An exponent aflixcd to a synlbol containing a prclix indicates Ihat Ihc ululliple or

submultiple of the unit is raised to the power expressed by the exponent.

I ninl _ = "10 -'_ ill _, not I0 -_ lit _

I Ciii _ = I0 <' III _, Illll I(I : nii

l cnl -I = l0 2 in -I , not l0 -2 ni "-I

7. A period is used as a decimal marker. It is not used to separate groups of digits.

A space is left for this purpose: 5 279 585 J, and 0.000 34 s.

8, Numbers are preferably expressed between the limits 0.1 and 1000, using the

appropriate prefix to change the size of the unit: 5.23 GN.

9. For decimal numbers less than 1, the leading zero is never omitted: 0.625, not .625.

10, When units are written in words, they always start with lowercase Ictters exccpt at

the beginning of a sentence. If the unit is derived from the name of a person, the

symbol is capitalized. Plurals of special names are written in the usual manner.

125 willis or 125 W

0.25 newton or 0.25 N

58.6 hertz or 58.6 Hz

11. A space or hyphen may be used to form the product expressed in words: newton -

meters or newton meters.

12. For quotients, the word per may be used: newton per meter squared, kilogram per

cubic meter.

13. The kelvin (symbol K) is the standard unit of temperature. In writing this absolute

temperature, the word degree or its symbol (°) is not used: 472 K. In addition, K

may be used to express an interval or a difference in temperature. Celsius temperature is expressed in degrees Celsius with symbol °C. The unit degrees Celsius

is equal to the unit kelvin and may also be used to represent an inlerval or a

difference of Celsius temperature: 25°C. Temperature in K -- temperature in

°C + 273.15.

138
DIMENSIONALHOMOGENEITY

Balancing of units in an equation is known as dimensional homogeneity. A simple example is

the formula (a mathematical rule that can be expressed by the proper signs and symbols) for the

area(A) of a rectangle, i.e. A = bxh where b represents the base and h the height. The units for

A must balance or be the same as the product of b x h. Failure to evaluate an equation for

substitution of the correct units that accompany the numbers assigned to each variable in the

equation is the downfall of many neophyte analysts. The Illustrative Problem on torque, printed

below, shows an example of this substitution.

Illustrative I'roblcm

Ih)w much torque (T) is needed to produce a shear stress of 79.6 MPa on the surfaceof a

4()-mm-dianletcr shaft with a polar moment of inertia (J) equal to 25.12 x 10-" m4?

Solulion

Tr

T = Pr _ = --

J

D

r - - 0.02 m _-J

2 T=--

r

79.6MPa x 25.12 x 10-sin 4

T=P.r =

0.02 m

_' =.02m 79.6 x 10'_N/r/a2 x 25.12 x 10-"m '¢

r=

0.02 ri1

= 999.8 N • m -_ I kN • m

T

This is a common practice when using the many formulas found in textbooks and other reference

works in which constants are expressed in terms of a number.

A classic example taken from a reference on machine design using U.S. Customary units is the

formula for calculating the torque on a round circular shaft transmitting a certain amount of

power at a particular speed.

T = 63 000 P/n

The constant 63 000, is the key that should remind students that this formula requires that the

correct units for both power (P) and speed (n) be used and no other. In this case the correct units

are horsepower and revolutions per minute with the result expressed in pound inches. Incidently

the student should be required to verify the value of the constant - 63 000. Further emphasis

139
should be placed on insisting that students substitute the units as well as the numbers for every

variable/term in an equation to ensure the proper units are arrived at in expressing the answer to

their computations. An example taken from the materials literature is the expression for thermal

shock resistance.

Thermal Shock Index(TSI) is a ratio of four variables. A complete discussion of TSI was

provided by L.Roy Bunnell of Pacific Northwest Laboratory and can be found in NEW:

UPDATE 1991. This figure of merit is an excellent tool for selecting ceramics with good thermal

shock characteristics. Regardless of what system of units are employed the TSI is expressed

using a standard set of units. If the units are mixed between the two systems of units the results

are useless. This ratio is an excellent opportunity to exercise the reader's knowledge of how each

of the four variables affect the resultant index.

(rXk

TS! -

axe

where

cr = tensile strength

k = thermal conductivity

ec = linear coefficient of thermal expansion

E = modulus of elasticity (Young's modulus)

THERMAL SHOCK INDEX (TSI) FOR SELECTED MATERIALS

Material _r (MPa) k(W/cm • °C) ot(°C-I x 10-") E (GPa) TSI'(W/em)

I;tl,,CdN.(): 1_8 (_ × 1112 0.6 "/2 94

AI:()_ 211-1, 3 × I11 i 5.4 344 33

Graphite 8.7 1.4 3.8 7.7 416

Soda-lime silica 69 2 x 10-2 9.2 68 2.1

gla+is

ITSI units in tile U.S. Cuxtom;iry system are Blu • in./hr/fl2; in the SI ._yslemthey are W/cm.

Illustrative Problem

I)cternfiuc the "l'SII't_r:uamid libcr and E-glass liber and indicate which has the best thermal

+,,hockresixtatlcc ba,_cdon Illct_ccalculations. Selected properties for each of the,_entaferials

are provided in the table that follows:

Aramid tiber E-Glass fiber

E = 18 x 10"psi E = 10.5 x 10"psi

cr = 400 x 10'psi cr = 500 x 10_psi

k = 3.5 Btu • in./hr • ft-"• °F k = 7.0 Btu • in./hr • ft2 • °F

_ :_ O.8 X IO "°F _(Iong.) a = 1.6 x I0 "°F -_

Solution

4 x 10_ x 3.5

TSI ........, = = 9.7 x I0' Bfu- in./hr, ft _

0.8 x IO " x 18 x IO"

5xlO'x7

TSIa:,_.,,, = = 2.1 x 10_ Btu • in./hr • ft2

1.6 x 10 " x 10.5 x 10"

Ar;iiiiitl Iibcr w:is Ihc t,lt+':lli+'rlind Iliclcl'llx'e tile best shc+ck resistance.

140
ASSUMPTIONS

One of the first steps in the analysis of a problem is that of making simplified assumptions. If

this step is done successfully what remains is what one believes are the determining factors. In

essence these assumptions not only simplify the problem but in many cases make a tentative

solution possible. The assumptions made are not forgotten but must be addressed in later

considerations to evaluate their affect, if any, on the solution. As one of the final steps the

assumptions set forth in the problem must be verified usually by conducting experiments to test

their validity. Examples of simplified assumptions are: the internal structure of a 20 ft steel Ibeam is homogeneous; the density of a solid ceramic body is uniform throughout; a surface is

flat; a solid material under load is rigid; or the shear stress increases in a linear fashion outward

from the neutral axis to the external surface of a shaft under torque (asseen in figure4-28below).

rma.= torsionalyield

strength

r = Torsional stress

rma, = Maximum torsional stress

outer surfaceof circular

rod

Figure 4-28 Distribution of torsional stress in a circular rod

A model is a representation of a mental picture of a problem just as a diagram represents

a play in a football game. A simple sketch of an atom is a model that helps one understand the

inner workings of atoms. An equation or formula is another example of a model which visually

represents a problem. Other examples are charts, functional plots, and diagrams (free body

diagrams, block diagrams, etc.). Functional charts or plots show relationships between variables.

All of these are used throughout the study of materials as evidenced by the various figures used

in this presentation. The use of a model and the mathematical equations that relate to it describe

simply and easily the precise 'physical theory' of the situation. Using Figure 4-3, note the

tssumptions made but not specified in the construction of the model. Using a model and its

tccompanying mathematical relationships, the mental process of analysis is used to calculate the

)ehavior of materials under various conditions of stress. This step in the process of engineering

lesign illustrates the need for all involved in the world of materials to gain expertise in applying

he tools of mathematics to every day problems.

141

I

I
I Noo.

I

i I

._ £ il ___ d

F _ F Load

A_ = 6_ = _ - t o Total axial deformation

Ad = 5d = d- do Total lateral deformation

Note: Deformations exaggerated for ilhlstrative purposes

Figure 4-3 Rod under a tensile stress

STATISTICS

The result of analysis of materials using the tools of mathematics rarely represents exactly the

physical behavior of 'real materials and devices'. Recall our discussion of assumptions. Further,

the introduction of errors plus the fact that all measurements rarely yield the same value add to

the fact that answers arrived at by whatever means are not true or exact. Consequently, the result

is, at best, a statistical average. The results of the analysis of most problems take the form of

a set of data. In other words the true magnitude of a property or quality of a material is a

distribution function that requires statistical measures for its solution. The task now is to obtain

the 'best value' of all the data or to extract the most useful information. To do this statistical data

reduction procedures are used. Such procedures as determining significant figures (fictitious

precision), or the accuracy of measuring instruments employ to a degree the tools of statistics.

Production inspection of manufactured parts, quality control, and sampling are other areas that

are based upon statistical measures. In the field of failure analysis, the concept of probability

must be further addressed to properly document the results of such analysis. Because of the

usual large amount of data involved, the computer is the tool to use to analyze it.

H.T.McClelland, University of Wisconsin addresses this subject in his paper "Introduction to

Usable Statistical Methods ", found in NEW:Upate 93.

COMPUTERS

An essential requirement in today's technological world is to be computer literate. Without an

understanding of the digital computer, its role, and its use, it is most difficult if not impossible

for a person to function in today's age. In addition to the computing power of a computer, the

use of computer spread sheets makes available most mathematical functions and statistical

quantities needed for calculation, searching tabular data, iterative problem solving, and the display

of numbers graphically for better visualization of the data. A review of NEW:Update 93

discloses that of 39 experiments described 9 (or about 25%) specifically mentioned the use of

142
a computer in conducting the experiment. One contributor mentioned prerequisite knowledge of

the basic application of the microcomputer and DOS commands as being essential ("Graphing

Techniques for Materials Laboratory Using Excel" by Nikhil K. Kundu, Purdue University). The

addition of automated data collection system to the Charpy Impact Tester allowed a single

student to conduct the experiment in half of the time previously required with a ten-fold increase

in the accuracy of the measurements. ("An Automated Digital Data Collection and Analysis

System for the Charpy Impact Tester" by Glenn S. Kohne and F. Xavier Spiegel, Loyola

College).

SUMMATION

A working knowledge of mathematics and microcomputers, plus the ability to apply it to

engineering materials technology experiments and other problem solving, permits one to more

efficiently learn new knowledge of materials and to apply that knowledge for ones own benefit

as well as for other members of our advanced technological society. Recognizing that students

will need assistance in improving their competencies in mathematics will enable instructors to

improve engineering materials technology teaching.

REFERENCES

1. Jacobs, James A. and Thomas F. Kilduff. Engineering Materials Technology, 2nd Edition,

Prentice-Hall, Inc. 1994. Figures and Tables listed used with permission granted.

2. Bunnell, L. Roy. "Tempered Glass and Thermal Shock Index", National Educators'

Workshop:Update 91 - Standard Experiments in Engineering Materials, Science and

Technology. NASA CP-3151, 1992.

3. Kundu Nikhil K. "Graphing Techniques for Materials Laboratory Using Excel", National

Educators' Workshop:Update 93 - Standard Experiments in Engineering Materials, Science

and Technology. NASA CP-3259. April, 1994.

4. Kohne, Glenn S. and F. Xavier Spiegel. "An Automated Digital Data Collection and Analysis

System for the Charpy Impact Tester", National Educators' Workshop:Update 93 - Standard

Experiments in Engineering Materials, Science and Technology. NASA CP-3259. April, 1994.

5. McClelland, H.T. "Introduction to Usable Statistical Methods", National Educators'

Workshop:Update 93- Standard Experiments in Engineering Materials, Science and

Technology. NASA CP-3259. April, 1994. April, 1994.

143

INCORPORATING "INTELLIGENT" MATERIALS

INTO SCIENCE EDUCATION

Robert J. Scheer

Research Scientist

Protein Solutions, Inc.

350 West 800 North Suite 218

Salt Lake City, Utah 84103

Telephone 801-596-2675

€

145
146
INCORPORATING "INTELLIGENT" MATERIALS INTO SCIENCE EDUCATION

Robert J. Scheer, Ph.D.

Project Director

Protein Solutions,Inc.

Salt Lake City, Utah

Presented at:

NEW/UPDATE 1994

Gaithersburg, Maryland

November 7, 1994

Outline

I. Rational and philosophy for the intelligent materials lab (8-10)

A. Provide "real reality" in the classroom (8)

B. Easily assimilated format

C. Provide a lab where one does not exist due to cost or logistics (9,10)

D. Free up instructor time for class preparation and student interaction

II. Review of basic concepts and themes covered in introductory polymer/materials class (1-7)

III. Handout of materials for exercises in polymeric and materials sciences.

A. DOP plasticizer gradient of poly(vinyl chloride)

B. Temperature responsive polymer, poly(N-isopropyl acrylamide)

C. Ion concentration responsive polymer, sodium polyacrylate

VI. "Do the lab"

147
Basic Concepts and Themes in Polymer Science and Engineering (1-7)

MolecularWeightand Distribution _-_

Thermoset/Thermoplastic

Steric Hindrances/Side Groups

Polymerization - -

Intermolecular Forces/Cohesive Energy Density

Entropy/Elasticity _ _

Morphology/Crystallinity

148
Temperature Transitions

Viscoelasticity

Surface versus Bulk Properties I I

Modifiers/Additives -__

Processing/Fabrication _ J"_

Optical Properties -lb..

Time-TemperatureSuperposition L __

149
Table.Explorationmaterialmatrixmatchedto introductorypolymerconceptmatrix.

TemperatureResponsive Polymer _ X X X

]

Ionic Responsive Polymer _< X X _<

Tg Homopolymers X _<

Heat Shrink Material )< X )< _

Composites X X

SurfaceGradient

Voight-MaxwellModels X X X X _

Shape Memory Polymer X X X l _ _

Crosslink Density Study X iX X _

Elastomer X X X X X

Polymerization Procedure X X X iX _

Spherulite Gradient X X X X ,X X X X

CrosslinkGradient X X X X X X'X

Plasticizer Gradient X X X X X X !X

Copolymer gradient X X X

i "i

•._. _-_ _

__ _.__ _ .__

150
Rational and Philosophy

Moststudentscome into polymercourseswith variousconceptsandpreconceptionswhich leadthem

to concludethatthe behavior and propertiesof pol_,mersarecounter-intuitive.It istherefore importantthat

they fullydiscover and observe the properties andbehavior of polymericmaterialsfor themselves.

A very large numberof science andengineeringcoursestaughtin colleges and universitiestodaydo

notinvolve laboratories. Althoughgood instructorsincorporateclass demonstrationsh, ands-onhomework,

andvariousteaching aids, including computersimulations,the factis thatstudentsin such courses often

accept key concepts andexperimentalresults withoutdiscovering them for themselves. The only partial

solution to this problem has been increasing the use of class demonstrations and computer simulations.

We are developing a set of inexpensive and convenient hands-on discovery based experiments which

the students can perform for themselves. The laboratory, although packaged like a textbook, will contain

within it all of the materials, equipment, and information needed to directly discover and experience key

conceptsrelated to polymer materials.

The experiments are based on:

1) actual materials commonly utilized in consumer products, and

2) a set of specially developed materials which the students can utilize to directly see and experience

complex concepts (8).

In both cases, the experiments and observations will utilize only the students' senses for

transduction and detection.

Another important area of education which this research will impact is the growing field of distance

learning. The Public Broadcasting Service (PBS) has developed a new program called "Going the

Distance." In thePBS's definitive guide to distance learning, Going the Distance (9), major issuesrelated to

developing a distance learning program are discussed. The guide points out special needs of the laboratory

sciences and distance learning. Others have addressed distance learning (9,10), and currently severalstates,

including Utah, axe strongly committed to the development of distance learning for secondary and postsecondaryeducation.

Uniqueness: The difference between our proposed laboratory explorations and those of other, more

common exercises is two-fold. The primary difference is in the required detection devices; our laboratories

require the human perceptions of both sight and touch, others often require costly (though no_.Amore t

sophisticated) detection equipment. This isthe very difference which allows the Labless LabTM to be used

outside the classroom. The secondary difference is the useof "intelligentmaterials" as teaching devices (8).

The students can utilize thesesmaterialsto directly see complex polymer concepts.

151
Plasticizer Gradient (PVC)

Observation # 1: Stiffness/Compliance

Draping Additives

LowM.W.Components

MolecularWeightDistributions

Viscoelasticity

Observation #2: Hardness

Elasticity

Indentation Viscoelasticity

Observation #3: Viscoelasticity

Glass Transition

Long MoleculeMobility

Molding Time-Temp. Relationship

Processing

IntermolecularForces

** PVC is a very common commercial material (car seats, irrigation pipe, Tygon® tubing). Its wide

range of uses and propertiesis due to different degrees of plasticization. This unique sample demonstrates

this concept handily.

152
Shape Memory Polymer (polynorbomene)

Observation #1: Glass Transition

Comparison of mechanical Elasticity

properties at room temperature

and at T>Tg IntermolecularForces

Observation #2: IntermolecularForces

Mold polymer when T>Tg GlassTransition

and cool,

;does it hold its shape?

Observation #3: MolecularMobility

Glass Transition

Reheat above Tg IntermolecularForces

** This polymer can be purchased as a novelty' from Maruyoshi® Co., Ltd. (Japan) Tel.

03(3470)6360. The raw/unformed polymer powder can be purchased from Zeon Chemicals, Inc. (USA)

Tel. (708)437-9770. It has been proposed for use in medical devices, particularly arterial stents. The idea

was to place the stent, in a collapsed geometry, into the artery; when the stent reaches body temperature it

will expand to support the artery.

153
Surface Wettability Gradient (polystyrene)

Observation #1: Intermolecular Forces §8.14, p.177

Sessile Drop Test Surface and Bulk properties §17.20, p.425

Observation #2: Intermolecular Forces §8.14, p.177

Peel Test Surface and Bulk properties §17.20, p.425

Observation #3" Intermolecular Forces §8.14, p.177

Capillarity Test Surface and Bulk properties §17.20, p.425

** Polystyrene is used for food packaging and compact disc cases. It is well suited to these uses

because of its transparency and hydrophobicity (it repels water). The transparency can be altered by adding

a foaming agent which also increases its temperature insulation properties (StyrofoamrM). The surface

chemistry can be altered (oxygen or water plasma) to demonstrate the effect of chemistry on surface

properties.

154
Temperature Responsive Polymer

(poly(N,isopropylacrylamide))

Observation #1: Intermolecular Forces §8.14, p. 177

Dry material properties Solubility and Concentration §8.14, p.177

compared to solution properties

Side Groups §15.6, p.327

Observation #2: Intermolecular Forces §8.14, p.177

Solubility and C.E.D. §8.14, p.177

Effect of different temperatures Optical properties §11.8, p.241

on solution properties Side Groups §15.6, p.327

IReversibility Observation #3:- Heating and Cooling II Solubility Intermolecular and C.E.D. Forces §8.14, §8.14, p. p.177 177

** The primary use of this product is for controlled chemical delivery systems, where the polymer is

used as a crosslinked gel. As a gel, the polymer expands and contracts in water solutions instead of

dissolving and precipitating as did the nonlinked sample demonstrated. This is not a commercial polymer.
Ionic Responsive Polymer (sodium polyacrylate)

Observation #1" Crosslinking §15.13, p.345

Dry material properties Elasticity §13.2

compared to

Hydrated gel material properties Morphology §11.8

Observation #2: Intermolecular Forces §8.14, p.177

Affect of different solutions Solubility and Concentration §8.14, p. 177

(saline, sugar water, food coloring)

Side Groups §15.6, p.327

Observation #3: Molecular Mobility §12.1

Reversibility - Heat,Agitation Intermolecular Forces §8.14, p.177

Observation #4: Viscosity §9.13, p.207

Solution Properties Molecular Weight §9.2, p.187

Cohesive Energy Density §8.14, p. 177

** Used in diapers to absorb liquids. Negative ions in solution take the place of the water and release

the water. Can be purchased from Flinn Scientific Inc. Tel. (708)879-6900.

156
References

I. Cowie, J.M.G.: Polymers: Chemistry and Physics of Modern Materials. Chapman and Hall, 199I.

2. Billmeyer, F.W.: Textbook of Polymer Science. John Wiley and Sons, 1984.

3. Young, R.J.: Introduction to Polymers. Chapman and Hall, 1981.

4. Cambell, I.M.: Introduction to Synthetic Polymers. Oxford University Press, 1994.

5. Rodriguez, F.: Principles of Polymer Systems. McGraw-Hill, 1982.

6. Carraher, C.: Polymer Chemistry. Dekker, 1992.

7. Seymour, R.B.: Recommended ACS Syllabus for Introductory Courses in Polymer Chemistry. J.

Chem. Educ., vol. 59, 1982, p. 652.

8. Andrade, J.D.; and Scheer, R.J.: Applying 'Intelligent' Materials for Materials Education: The

Labless LabTM. Proceedings of the Second International Conference on Intelligent Materials. C.A.

Rogers, and Williams, G.G., eds. Technomic, 1994.

9. Toby Levine Communications, Inc. Bethesda, Maryland. Going the Distance: A Handbook for

Developing Distance Degree Programs Using Television Courses and Telecommunications

Technologies." Annenberg/CPB Project and PBS Adult Learning Service, Corporation for Public

Broadcasting and Public Broadcasting Service. 1994.

10. Watkins, B.T. "Uniting North Dakota." The Chronicle of Higher Education. Aug. 10, 1994, p. A17.

11. More details on preparation of these samples and their uses will be published in the Journal of MaterialsEducation to be submittedmid-December.

157

MEASURINGENERGYLOSS BETWEEN

COLLIDINGMETALOBJECTS

Bernard J. Weigman

Department of Physics and Computer Science

Loyola College

4501 North Charles Street

Baltimore, Maryland 21210-2699

Telephone 410-617-2000

and

Stamos Courpas

Graduate Assistant

Department of Physics and Computer Science

Loyola College

Baltimore, Maryland 21210-2699

159
160
Measuring Energy Loss between Colliding Metal Objects

Bernard J. Weigman

Professor

StamosCourpas

Graduate Assistant

Dept. of Physics and Computer Science

Loyola College

Baltimore, MD 21210

Key Words: Coefficient of restitution,kinetic energy

Prerequisite Knowledge: Knowledge of basic mechanics, conservation of energy

Objective: To determinethe loss of kinetic energy when a metal sphere bounces off of a flat,

hard metalsurface. To determinehow thisloss of kinetic energyis relatedto the kinetic energy

just before impact. To measure very short times electronically.

Equipment:

1. collection of metal spheres of various diameters

2. a small microphone

3. LM324 operationalamplifier

4. 74121 monostablemultivibrator

5. a "first and second pulse" detector

6. a 10 Khz crystal controlled squarewave generator

7. a 7 digit counter

8. a meter stick accurateto 0.5 mm

9. a fiat, hard, fairly massive metal surface

10. an RC - diode filter

11. 7414 schmitt trigger

Introduction

The coefficient of restitution between two collidingsurfacesis defined as the ratio of the

magnitudeof the relativevelocitiesafter impactto the magnitudeof therelativevelocitiesbefore

impact. If one object is falling and has a speedv just before hitting a stationary surface and

rebounds with a speed v' just after hitting the surface, the coefficientof restitution_e can be

definedas

v !

e=-- (1)

v

161
In a perfectlyelasticcollision,e wouldbe equalto 1. If theball is droppedfromrestfroma

heighth, its kineticenergyjustbeforehittingthe flooris2

l--ray =mg2h (2) 2

h

Figure 1 Falling Sphere apparatus

Afterthe sphererebounds,it will have a speedv' and willrise to a heighth' where it will have

potentialenergy

mgh/=Imv:z (3) 2

162
Combining equations 2 and 3, we see that

/ /

(4)

v h

Thus from equation 1

e= (5)

Measuring h' becomes very difficult when h gets to be small. For this reason, an alternative

approach has been developed to measure h' and thus e.

Since the sphere will rise to a height h' before coming to rest and starting to fall back to the flat

surface, the time that it takes to come to rest at height h' is just t where3

h/=Igt2 (6)

fromwhichwe get

t=_ --2ght- (7)

The time for the sphere to hit the flat surface from the top of its trajectoryis also t so the total

time between the first and second bounce is T where

T=2t (8)

Combining equations 5, 7 and 8, we get

T=e_hg (9)

163
Thus for a given initial height h, we can measure the time T between bounces and find e.

e=T_--_ (10)

The quantity e is related to the loss in kinetic energy due to the collision. The kinetic energy

before impact is given in eqn 2 while the kinetic energy after impact is given in eqn 3.

The loss of kinetic energy due to impact is

6KE=lmv2-1mv:2 (11)

2 2

The ratio of the loss of kinetic energy to the initial kineticenergy is given by

1,nv:_l,nv:

8KE_ 2 2 =l_V :2 (12)

KEo lmv2 v 2

2

From equation 1:

8KE=I-e2 (13)

KEo

And finally from equation 10:

8KE- 1 gT2 (14)

KE 8h

Thusfor a giveninitial heighth, thepercentageloss of kineticenergy can be determinedby the

measuringthe time between the first and secondbounce.

Apparatus

In order to measure the times betweenbounces, we designeda circuit to detect the noise that

the sphere madewhen it hit the flat surface.For this we useda microphone.After amplifying

the output of the microphone,we fed the amplifiedsignal to an analogcomparatorto produce

outputs that were +5 volts or ground.These signalswentto a schmitttrigger to sharpenthe

pulses and make them qTL compatible.Finally, a monostablemultivibratorwas triggeredon

the first 0 to I transitionand stayedhigh for a timedeterminedby its RC time constant untilall

164
the ringing from the noise vibrations were finished. The time was made long enough to mask

all vibrations but the first and short enough to be ready for the next bounce. Effectively, each

time the sphere bounced, a single logic 1 pulse was produced which stayed high for about 30

milliseconds. See Appendix I.

The output of this control circuit was fed to a pulse detector which was a digital circuit

containingD type flip-flopswhich went high when the first pulse came along, low when the

second pulse came along and stayedlow for all followingpulses until manuallycleared. The

outputof this circuitwasANDedwitha 10Khzclockand theoutput of the ANDgate wentto

a counter. Thusthe numberof countswas a directmeasurementof the timeT betweenbounces

measuredin tenthsof milliseconds.

Procedure:

A metal sphere is held by a release mechanism which allows the sphere to be dropped from the

same height on each trial. The distance h from the flat surface to the bottom of the sphere is

measured using a meter stick and recorded in Table I. The counter is cleared and the "two

bounce detector" is reset. The sphere isreleased. When the sphere hits the surface the first time,

the counter begins to count. When the sphere hits the surface the second time, the counter stops

counting. All subsequent bounces are ignored by the counter. The number on the counter is the

time T between bounces in units of 0.0001 seconds. This number is recorded in Table I. This

is repeated 5 times. The average and the standarddeviation are computed and also entered into

table I. This procedure is repeated for 7 different heights as indicated in Table I. We also

measured and recorded the mass and the diameter of the sphere. The clock frequency is recorded

in Table I as is the gravity constant g which appears in equation 14. In Table II, the percentage

loss of kinetic energy is calculated from equation 14 using the experimentally determined values

of h and T. The value of g is recorded as 9.80 m/sec2. The coefficient of restitution e is also

calculated using equation 10 and displayed in Table II.

Results:

The data in Table II is presentedin two differentgraphs. In figure 2 the percentage loss of

kinetic energy is plotted versus kineticenergy before impactand in figure 3 the coefficientof

restitutionis plottedversusinitial heighth. Asthe graphsindicate,thepercentageof energy lost

upon impact decreaseswith decreasinginitial totalenergy and the coefficientof restitutione

decreaseswith increasinginitialheighth. The studentis givennoexplanationfor this. He orshe

is asked to try to explainwhy this mightbe the case.

165
TABLE I. Data Collection for Sample Run

h(em) 1.00 2.00 3.00 4.00 5.00 6.00 7.00

run 1 503 668 785 894 960 1043 1099

run 2 504 663 780 876 959 1023 1105

run 3 497 660 778 871 957 1041 1112

run 4 499 660 777 885 944 1037 1109

run 5 498 668 783 887 954 1050 1100

Average 500.2 663.8 780.6 882.6 954.8 1038.8 1105.0

st.dev. 2.1 2.7 2.3 6.2 4.4 6.8 3.8

T(sec) 0.0500 0.0664 0.0781 0.0883 0.0955 0.1039 0.1105

mass of sphere= 0.012 kgm

gravity g= 9.80 m/see/see

diam of sphere= 1.43 cm

clock freq= 10000 Hz

166
Per-cent energy loss vs

klnetl¢ enirgy l>eforl Inl_ICt

80

79

! ,o _.

72

71

711 /

69

1.178 2,352 3.528 4. ?04 5• 8eo 7. 058 8,232

i_EI:_fOl'll ImpaCt.OralI IIJGull_l_l

Figure 2 PercentKE loss vs initial energy

Coefficient of restitution vs

IrtltlBI helQht of ilphar't

0.SS

0.55

O. 53

_ o,,_ ,,,, o.sl

__ o._ u

i °." ""-

0.46

\

0.47

0.48

0.01 0.02 0.03 0.04 0.05 0.08 0.07

h Cruets-s)

Figure 3 Coefficientof restitutionvsinitial h

167
TABLE II Calculations of e and energy loss

Avg h(m) Initial % KE e

T (see) mgh(mJ) loss

0.0500 0.01 1.176 69.4 0.554

0.0664 0.02 2.352 73.0 0.520

0.0781 0.03 3.528 75.1 0.499

0.0883 0.04 4.704 76.1 0.488

0.0955 0.05 5.880 77.7 0.473

0.1039 0.06 7.056 78.0 0.469

0.1105 0.07 8.232 78.6 0.462

References:

1. Roller and Blum, Physics Volume 1,Holden Day, p210

2. McLean and Nelson,Engineering Mechanics - Schaum's Outline Series,

McGraw Hill, p320

3. R. C. Hibbeler, Engineering Mechanics: Dynamics, Macmillan, p439

168
APPENDIX I BOUNCE DETECTION CIRCUIT

169
/"
STRESS CONCENTRATION:

COMPUTER FINITE ELEMENT ANALYSIS

VS. PHOTOELASTICITY

Vernon S. Hinsman

Mechanical Engineering Technology Department

Purdue University

1417 Knoy Hall

West Lafayette, Indiana 47907-1417

Telephone 317-494-7486

171
172
Stress Concentration:

Computer Finite Element Analysis vs. Photoelasticity

Vernon S. HiUsman

Mechanical Engineering Technology Department

Purdue University, West Lafayette, Indiana, 47907

KeyWords: finite element analysis,stress concentration,photoelasticity,maximumstress

Prerequisite Knowledge:Studentsshould have a basicunderstanding of applied strength of

materi.alsthrough principalstresses and strains, and a prior laboratory coveting

plaotoelasticmethods isrecommended. Studentsshouldbe computer literate. Prior

computer aided design training is helpfulwhen developingthe geometry of the computer

models, but is not required.

Objective: To gain insightinto stress concentration due to geometricdiscontinuities. To

compare computer finite element analysiswith traditional methods used to determine

stress concentration factors and maximumstress at geometric discontinuities.

Equipment:

1. Computer with finite element analysissoftware

2. Birefringent plastic test specimen(s)

3. Transnussionpolariscope with load frame and load cell

4. Digital readout for loadcell

5. Tables ofstress concentration factorsfor variousgeometric discontinuitiesand

loadings

Introduction: The elementaryformulasfor average stress and strain presented in most

mechanics of materials courses are based on members that have constant, or gradually

changing,cross-sectional area. However,thisis not usuallythe case in actual machine parts

or structural members where shoulders,notchesholes or other geometric discontinuities

result in a modification of the simple average stress distribution. A small discontinuityin a

member will generally increase stresslocally,with the increase being out of proportion

when consideringthe nominal cross-sectionalarea and applied load. The stressraising

effect of a discontinuity resultsin a maximumstress that normallyoccurs at the boundary of

the discontinuity. These maximumstress valuesmust then be address when designing

actual load bearing members.

The stress concentration factor (SCF) isthe ratio between the maximumstress and the

nominal stress. Values for the SCF formembers with commongeometric discontinuities

(notches, holes, shoulders, etc.) can be found in tabular form (1,2)for variousload cases.

Multiplyingthe SCF by the nominalstressreturnsthe maximumstress in the cross-section

containing the discontinuity.

The photoelastic method can also be used to determine maximumstress at a discontinuity,

and provides a visual representation of the stress distribution in the model. When using a

transmission polariscope, a birefringent,uniform cross-sectioncalibration specimen is used

to determine the fringe constant of the modelingmaterial. SCF and maximumstress can

then be calculated using the photoelasticstress opticformula (3). Care must be taken to

173
obtain a number of readingswhen using photoelasticity,since the load at whicha fringe

becomes visibleis an arbitrary decisionmade by the observer.

Microcomputer based finite element analysis(FEA) also provides a visual image of the

stress distribution around a discontinuity,and the FEA program will provide values for

stress at any location on the computer model. Comparingthe computer generated image

with that found from the photoelasticitytest is a quickway to verify the accuracy of the

computer model. Experimental verification of FEA models helps students gain confidence

in their abilityto correctly develop the computer models. The computer modeling was

done using the microcomputerversion of COSMOS/M, Version 1.61,from Structural

Research and Analysis Corporation.

Procedure: The maximumstress at a discontinuityisto be found and compared using

three different methods; computer FEA, reference tables and photoelasticlty. The pattern

of stress distribution developedfrom FEA willalso be compared to that observedusing

photoelasticity.

The test specimen is made of a birefringent plastic that is 0.117inches thick, and has a

modulus of elasticity of 360,000psi (see Figure 1). The load isto be 50 pounds tension

along the x-axis,applied at the ends of the model or test specimen. It isrecommended that

the experiment proceed in the followingorder: FEA, reference tables, photoelasticity.

¥

_X j1⁄2" Dia Thru Hole

Figure 1. Model used for stress concentration experiment

Finite elementAnalysis(FEA). Regardless of the object to be modeled, finite element

analysisfollowsthe same basic pattern; the user mustspecifymodel geometry, element

type, mesh densities,sectionproperties, material properties, constraints and loading. After

the model specificationsare complete, the type(s) of analysisrequired is executed and then

the output form isspecified. This output can then be compared to that found using the

reference tables or photoelasticity.

First, the model geometry isinput per the specificationsin Figure 1. This can be quickly

accomplishedsince the model consistsofjust twobasic geometric shapes, a circle and a

rectangle, and willbe represented as a two dimensionalmodel with constant thickness.

The stress concentration specimencan best be represented by two dimensional elements

that have a constant thickness. COSMOS/M uses the term PLANE2D to represent this

type of element. The surface ofthe computer model must now be "meshed",whichmeans

that the surface of the model isto be completelycoveredwith PLANE2D elements that are

joined at their corners, or nodes.

174
Typically,high mesh densities(many elements in a unit of area) willreturn more accurate

resultsthan low mesh densitiessincevalues for stress and strain will be computed for each

element. However, increasingthe number of elements increasesthe computer time

required to run the FEA model,so highmesh densitiesshould onlybe used in areas of

specific interest, such asthe area around the discontinuity. The stress concentration model

in Figure 1is also symmetricabout both the X and Y axes,so thisspecimen can be most

efficientlymodelled through the use of a quarter section to further reduce the problem

size. Boundary conditionsmust nowbe enforced on the quarter section so that it properly

represents the entire stress concentration specimen (4).

The 50 pound tensile load isthen applied to the computer model, and a static analysisis

specified. Results from the analysiscan then be displayedon the computer screen as a

stress plot, as shownin Figure 2. The stress distribution from the computer model can now

be visuallycompared with that of the photoelasticityexperiment. Values for the

magnitudes of the stress contours are also shown on this plot.

tlorlllises

II-', =-..2 2E',.'9-_

" '.... l!e', se!,zs ',,.I / /)' / /' ", / X '\.

:,:" ," ",., X '\,. 1t",2 :'_42.15 "t

L. ". \,,.[] 20, _2. '_5

", "",,. "g 9, __=_.,.,_

/"'' \' "\ m-' _-.,aa. i-_

L ""'% '...... 'X _X. []_, _',--eI. _5

',..,_..,. ,. i_-,::_ _.'25. '

'%...._.---,. , \

dq%

"L '%',

._---_.,. ,. \ ',, " ' L

., _. ', v _ \ '' '\ ,_ ... '_%.\

Figure 2 Stress distribution plot

Reference tables: Students use reference tables (1,2)to determine the stress

concentration factor (SCF) for a model with geometry asshownin Figure 1. The nominal

stress isthen calculated based on the cross-sectionthat contains the discontinuity. The

maximumstress isfound from multiplyingthe nominal stress by the SCF. This can then be

compared to the resultsfor maximumstressfound using the FEA model.

Photoelasticity: Students are giventhe stress concentration data from a previous Applied

Strength of Materials laboratory, as shownin Figure 3. The data include the specimen

dimensions,fringe constant for the specimenmaterial, and sufficient informauon from the

experiment so that a stress concentration factor can be calculated. The maximumstress

due to a 50 lb. applied load iscalculated, and can then be compared with results based on

both reference tables and FEA.

A birefringent test specimen (see Fig. 1) isthen placed in the load frame of the polariscope

and a 50 lb. load is applied. The stress distribution pattern developed is observed and

compared to the stress distribution developedusing finite element analysis.

175
/__.._.__.__ /

'D_ i'IIOTOI_LASTFCITY DATA ;:III_L:'{."

._ of _o 16s.

r.11Ibrtrlon Pa_

Frhw.o I l:_dou_,z ;¢,_ A_3

o._o " I ....' "°°' ....._'_L__'.___L. __

//5-

l,q.y_ _, II. 33 5Z,.I_,5"

I'rln_o i Moo,lo_, I ^VJ ^'/C_ { ema,: ere-_

_,.= O.IIS4 ,u._ °',,' _,.., ._,,.2....: , ...

• ,s ........ _.g3 m,/,.-!32fl I,_.

- =

• I , u,';'l\ _11_.... qgO 48:z

""" , uJ__.._J ....t..,._ l //'/z '77,1 __

<-- I,.cot-.>

Figure 3 Photoelasticity data sheet

Conclusions: A table of the maximumstressesfound using each method should be

developedfor comparison.ofthe results. A comparisonof the stress distributionpatterns

found byFEA and photoelasticitycan be done usingphotographsof eachtechnique,

howeverit may be more convenientto set up a microcomputernext to the polariscopeand

auowstudents to pzottheirFEA resultsduringthe photoelasticity experimentfora realtime comparison.

Instructor Notes: This experiment was used in a course on Applied Finite Element

Analysis as an exercise in experimental verification of FEA results. Students with a solid

CAD background and good computer skills are able to quickly learn to develop FEA

models, but seem to have difficulty with properly meshing a model, applying boundary

conditions and properly interpreting results. The use of proper mesh densities is easily

shown using a very simple model that includes a stress concentration; highermesh densities

near the discontinuity for greater accuracy,lower mesh densities in the main body of the

model for efficiency. The model used here also provides an opportunity to develop

boundary conditions for the quarter section used in the FEA analysis. Students have a

tendency to accept any output generated by an FEA pro_am, so the verification

experiments are used as a tool to increase students' confidence in their ability to generate

accurate FEA models.

References:

1. Roark, Raymond J., Roark's Formulas for Stress and Strain, 6th Edition, McGraw-Hill,

Inc., New York, NY 1989

2. Cheng, Fa-Hwa, Applied Strength of Material_, Macmillan Publishing Company, New

York, NY 1986

3. "Student Manual on the Photoelastic Coating Technique", Bulletin 315-A,

Measurements Group, Inc. 1984

4. Baran, Nicholas M., Finite Element Analysis on Microcomputers, McGraw-Hill Book

Company, New York, NY 1988

176
FAILURE ANALYSIS OF INJECTION

MOLDED PLASTIC ENGINEERED PARTS

Jerry L. Wickman

Plastics Research and Education Center

Departmem of Industry and Technology

Ball State University

Muncie, Indiana 47306-0255

Telephone 317-285-5648

and

Nikhil K. Kundu

Purdue University

Statewide Technology

2424 California Road

Elkhart, Indiana 46514

219-264-3111

177
178
Failure Analysis of Injection Molded

Plastic Engineered Parts

J.L. Wickman

Ball State University

N.Kundu

Purdue University

Key Words: Fractography, Fracture, Service life, Polymer

Degradation, Failure Analysis,

Prerequisite Knowledge: Knowledge of plastics injection molding,

materials testing, quality control,

plastics as an engineered material, and

ASTM standards are beneficial.

Objective: To locate a suitable injection molded engineered

part. Analyze the part, materials selection,

probable processing characteristics and design as

dictated by the parts intended function, and

develop a plan using design of experiments (DOE) to

exhibit planned laboratory failure.

Equipment: Various test equipment sensitive enough to show

results when testing plastics, i.e., impact,

tensile, compression, friction, hardness,

stiffness, dimensional, melting point and

viscosity/flow characteristics, plus other tests as

needed.

Various chemicals, fixtures, gages, environmental

conditions, ovens, analytical balance, software

packages (statistical, material selection, part

design, and other packages) to assist in the

analysis of the parts.

Multiple copies (approximately 6) of the selected

part to be tested and an abundance of insight, and

analytical, synthesis and observation skills plus

the time required to thoroughly analyze the

implications of the DOE process on part failure.

Introduction:

Failure as defined by ASTM D 1780, (one of many related

definitions) is rupture of the specimen, or exceeding the strain

requirements of a specific design. Whereas analysis is defined by

ASTM E 135 as the ascertainment of the identity or concentration,

or both, of the constituents or components of a sample. Failure

analysis can then be defined as the ascertainment of the identity

of the strain(s) exceeding the requirements of a specific design.

179
This laboratory combines failure analysis with design of

experiment, it is to be used in a senior level DOE (ITMFG 425)

capstone course. The laboratory is intended to last for 8 to i0

weeks and represents a major portion of the lab grade. Design of

experiment is defined as the process of planning an experiment.

Failure analysis and DOE is quite literally a planned experiment to

evaluate the design of a product after the fact. Designing an

experiment can work both in the assembly of a product

(manufacturing) and also in the disassembly, gradual or rapid

failure of a product or component. The benefit of using DOE in

failure analysis gives one a target, the failure of a part or

product. Working backwards from the failure one can produce a more

robust product. What is involved in this process can range from but

is not limited to the topic of DOE to systems design, materials

testing, testing standards, material, processing, applications of

technology, literature searches, materials testing, processing

variation and control, software, data collection, and fixtures and

fixture design (gage R&R).

Failure analysis of an injection molded plastic product is a

convenient, but not an easy approach to understanding the impact of

DOE, materials and processing. The plastic products are readily

available, selection of the part itself requires some engineering

analysis, the cost is minimal, the methods used to induce failure

are varied, and fixturing and testing of the parts can be done

quite easily. The problem with using injection molded parts may be

the quantity of unknown items, which is at times typical in failure

analysis.

A cornucopia of problems associated with the actual part failure

exist. The researcher must find a plausible, defensible cause for

failure. With an injection molded part causes for failures (to list

a few) may be any one or a combination of the following;

Materials problems

Thermal degradation

Excessive molecular weight distribution

Appropriate viscosity or changes in viscosity

Sampling procedures

Material selection

Blends ofmaterial

Contaminants

etc...

Part design

Proper radii

Size of bosses

Fasteners and their use

Forces anticipated

Cost

Location of sprue, runners and gates

etc...

180
Processing

Material conditioning

Resident time

Internal pressures and shear characteristics of material

Internal temperatures

etc...

Consumer use and abuse

Chemicals

Temperature

Radiation

etc...

Several of the experimental stress analysis techniques that have

been developed for metal applications can be used for injection

molded plastic parts. Some of the experimental techniques used for

stress analysis are:

* Brittle coatings

* Strain gages

* Photoelasticity

* Solvent testing.

Brittle coatings are based on perfect adhesion of a strain

sensitive coating applied on the surface of the part to be tested.

As the part is loaded, strains developed in the part are

transmitted to the coating which first begins to crack at its

sensitivity threshold in the area of the largest principal stress.

The cracks tend to be perpendicular to the direction of the

principal stress.

Strain gages of several types exist, acoustical, electrical,

mechanical, optical and pneumatic. Electrical strain gages tend to

be the most readily available and can be very easily adapted for

use in failure analysis. There are four major categories of

electrical resistance strain gages:

i. Unbonded-wire gages

2. Bonded-wire gages

3. Bonded-foil gages

4. Piezoelectric gages.

The most popular and useful for molded plastic part use is the

bonded-foil gages. Foil gages can be cemented easily to almost any

shape. The co-efficient of linear thermal expansion of plastics is

a factor to consider when using sensitive strain gages.

Photoelasticity - Using polarized filters and white light with some

transparent and opaque plastics (ASTM D 4093), they will tend to

show fringe patterns. The fringe patterns represent the overall

stress distribution present in the part. Interpretation of the

fringe patterns can lead to quantitative measurements of the

magnitude and direction of the stress as molded into the part or

induced through handling or the part in its actual environment.

181
Solvent testing - Stress as molded into a part or applied has an

adverse impact on the chemical resistance of the material. The

molded part can be saturated (sprayed or dipped) with a solvent of

predetermined strength at a specified time and temperature, then

cleaned to observe cracks and/or crazing. Any visual changes

indicate that the stress levels in the area of the molded part are

greater than those not effected. This method is indicative of

stresses only, either that the stresses (compressive or tensile)

are present or absent. Typical household solvents (cleaners) can

be used with a variety of materials, the solvents are very specific

to a particular plastic. Toluene with n-propyl alcohol and ethyl

acetate with methyl alcohol works well with polycarbonate relative

to generating cracks or crazes with reference to stress

concentrations.

Depending on the part design, material selection, and application

various combinations of the above techniques can be used with

typical equipment and fixtures available in a materials test

laboratory and/or metrology laboratory. For example, photoelastic

measurements can be used in combination with a coordinate measuring

machine. Fringe patterns/order and associated stresses on the part

can be correlated over a range of forces on the part. Solvent

testing can also be incorporated to enhance failure and analysis.

Procedure:

i. Obtain an injection molded engineered plastic part, depending

on the DOE, obtain approximately six duplicate parts. Part

selection should be based on the intent of this laboratory,

DOE/failure analysis, not on availability of parts.

Many products exist that are suitable for this laboratory. The

list of products are endless and can be found in stores

ranging from industrial supply (hydraulic, electrical,

plumbing, and construction) to office, medical, engineering

supply and even housewares.

Collect and document all available information relative to the

part, where it will be used, what properties might be expected

of the part, what will be the expected environmental

conditions for the life of the part (this includes shipping),

consider consumer use and abuse, processing considerations

and any other supportive information relative to your failure

analysis.

The following may provide some insight into the selection

criteria for the part;

Design characteristics of part

Mating part characteristics if any

Bolts-torque settings and variation

Screws-design and size variation

Snap fits

Bonding

Drilled holes

182
Molded in holes

Part loading

Gating of part and system

Plastic flow into cavity

Amorphous polymer chain orientation

Crystalline polymer chain orientation

Sprue/runner/gates

Size

Location

Balanced cavities

Polymer materials properties

Physical

Mechanical

Dimensional

Chemical

Electrical

Processing

Part environment

Temperature

Humidity

Light

Chemicals

Pressure/vacuum

Stress concentrations

What properties can be tested in your existing

facilities?

Mechanical

Physical

Dimensional

Chemical

Electrical

2. Assume failure(s) of a particular type, defend and justify the

parts possible failure(s) based on;

Literature search

Material characteristics

Processing precautions-sensitivity to heat/moisture

Design criteria of specific material

Material selection

Processing characteristics

Gating

Amorphous/crystalline

Processing data

Material handling

Drying

Assembly processes

Machining

Bonding/joining/etc...

183
3. Develop the DOE to induce laboratory failure and maintain

subsequent analysis and documentation.

Determine possible failure analysis schemes

Develop quantitative analysis procedures to support

findings, know what properties need to be evaluated and

how they will be evaluated.

Consider fixtures needed for testing

Consider testing options

Identify critical properties

Develop test criteria to show slow gradual part failure

(planned vs. actual) using available equipment as listed.

Chemical stress analysis may be used as needed to enhance

failure. A clear or transparent part will facilitate the use

of ASTM D 4093 and make failure analysis more thorough.

Slow failure implies gradual failure as evidenced by a variety

of quantitative changes over time, i.e., visual, dimensional,

shape, etc...

Develop quantitative analysis procedures to support findings.

Document what works vs. what doesn't work to highlight

tendency towards part failure. Maintain an accurate log of all

activities.

Select the appropriate part tests based on available;

Equipment

Environment

Tools

Fixtures (fixture design)

Fixture availability

Sampling procedure

Samples available

Materials ID

Material specs

Time to run tests

Quantitative data available (data collection)

Forces used vs. time required for results

Notes to the Instructor:

Keep the selection of parts to the less complicated designs.

Keep testing and fixtures as simple as possible.

Rubber tooling

Epoxy

Other cast materials

Assume sample sizes of 1 or 2 are acceptable.

Assume data from test results using a small sample size are

valid.

184
Because of the possible complexity of this project, encourage

students to work in groups of 2 to 3.

References:

A.J. Durelle, E. Phillips and C.H. Tsao, Introduction to

Theoretical and Experimental Stress Analysis, McGraw-Hill Book

Company, NY, 1958.

J.W. Dally and W.F. Riley, Experimental Stress Analysis, McGrawHill Book Company, NY, 1965.

R.D. Moen, T.W. Nolan and L.P. Provost, Improving Quality Through

Planned Experimentation, McGraw-Hill Book Company, NY, 1991.

A.S. Redner and W.E. Nickola, Measurement of Residual Strains and

Stresses in Transparent Materials, Experimental Techniques, Vol.

#2, February 1984.

S.R. Schmmidt and R.G. Launsby, Understanding Industrial Designed

Experiments, Air Academy Press, Colorado, 1992.

185

DEMONSTRATIONS IN MATERIALS SCIENCE

FROM THE CANDY SHOP

F. Xavier Spiegel

Department of Electrical Engineering and Engineering Science

Loyola College

4501 North Charles Street

Baltimore, Maryland 21210-2699

t

Telephone 410-617-2515

187
188
DEMONSTRATIONS IN MATERIALS SCIENCE FROM THE CANDY SHOP

F. Xavier Spiegel

Department of Electrical Engineering and Engineering Science

Loyola College, Baltimore, Maryland

ABSTRACT; Readily available items from the candy

counter at any supermarket or other stores can be used to

demonstrate such properties as elasticity, plasticity,

composite behavior, ductile and brittle fractures and

luminescence.

REQUISITE KNOWLEDGE; Curiosity.

KEY WORDS; Composite, Elasticity, Plasticity,

Ductility, Fracture, Triboluminescence.

OBJECTIVES; The purpose of these demonstrations is to

illustrate some interesting properties of some candy

products. 1,2

EQUIPMENT AND SUPPLIES; i) Chewing gum (sticks)

2) Chewing gum (coated)

3) Hard candy

4) Coated chocolate candy

5) Taffy

6) Peanut brittle

7) Licorice

8) Wintergreen mints

CHEWING GUM; Pull a stick of gum from both ends. The

gum will deform in a ductile manner, i.e. when it fractures,

you can note a necking area and considerable deformation. If

the gum is put in the freezer to cool for about fifteen

minutes, you can cause the gum to break in a brittle manner.

This phenomenon is known as a ductile to brittle transition,

and is very important in designing structures which will

experience variations in temperature. A similar fracture can

be demonstrated if you allow the gum to lose moisture and

become stale. The loss of moisture causes the gum to become

less ductile. Wood exhibits a similar behavior and has

drastically different mechanical and thermal properties when

the moisture has been removed. Taffy can be substituted for

gum in this demonstration.

COATED GUM; Gum is coated for several reasons such as

to give the customer a double treat, a sweet rather hard

candy and chewing treat, and also for convenience of

packaging and the added convenience of not needing a

wrapping. Coated gum is an excellent example of one type of

composite where a coating is placed on another material to

protect the inner material from deterioration. Regular gum

without a wrapper or coating would become sticky and lose

its appeal, and usually not be very appealing. Coatings such

189
as zinc on steel, paint on wood or walls, and asphalt on

foundations are used to protect these materials from the

outside elements and provide corrosion resistance, esthetic

appeal, and waterproofing respectifully. Coated chocolate

candy can be used in this demonstration.

HARD CANDY; Any hard candy can be used to demonstate a

brittle fracture. Hard candies are meant to last longer than

other candies and give the consumer a lengthier taste

experience. Striking a hard candy lightly with a hammer will

result in several pieces of candy. Quite often designers

need very hard materials which can withstand large loads

without deformation. Foundations and superstructures for

large buildings are examples of brittle materials.

PEANUT BRITTLE; Peanut brittle is a combination of a

syrup (taffy-like) and nuts. The nuts are added to the syrup

to provide a double treat, and this addition of nuts also

changes the mechanical properties. The pure brittle would

act in a typical brittle or hard manner, however when the

nuts are added the brittle is strengthened. Although this

may not mean much to the consumer it is an important

materials result. This phenomenon is an example of another

type of composite. In this case two different materials are

combined as a mixture to enhance the properties. In the case

of peanut brittle,the manufacturer wants to enhance the

taste, and incidentally has changed the mechanical

properties. Concrete is a mixture of stones and cement which

is the most abundant building material in the world. The

Egyptians added straw to clay to make more durable bricks,

and steel or composite bars or mesh are added to concrete to

improve the load bearing capacity.

LICORICE; Licorice sticks come in a variety of colors.

The color is added to appeal to the desires of the consumer.

If a licorice stick is pulled gently from opposite ends and

then released the licorice will deform, but then almost

immediately return to its original length, pull a little

harder and it will deform but take a little longer to return

to its original length, pull even harder and the licorice

will become permanently deformed. This behavior is known as

elasticity, anelasticity and plasticity. Continued pulling

on the licorice will cause a ductile fracture. Many

engineering materials are designed to take advantage of this

range of behavior of materials. Certain alloying elements

are added to a material to change the range or limit of this

type of behavior. Carbon in iron, silicon in aluminum,

copper in zinc and tin in copper are excellent examples.

WINTERGREEN MINTS; Any wintergreen mint has the

wintergreen flavor added to enhance the taste and appeal to

a certain consumer. However, the wintergreen flavor enhancer

adds an unexpected added attraction. When the mint is broken

in a darkened room, you will note a flash of light. This

190
phenonmenon is called triboluminescence. A mechanical

deformation results in the emission of light energy. Other

examples are bioluminescence, chemoluminescence and

electroluminescence, each named for the phenomenon that

causes the emission of light. Examples include fire-flies, a

propeller's wake at night, a swimmer's wake at night,

certain xhemical reactions, etc.

CONCLUSIONS; The author has performed these

experiments and demonstrations to audiences of all ages with

enthusiastic results. 3,4,5 Quantitative results can be

measured and each demonstration can be expanded and/or

altered to your desires. You are only limited by your

imagination and curiosity.

REFERENCES;

i. Jacobs, James A. and Kilduff, Thomas F. :

Engineering Materials Technology, Prentice-Hall 1993.

2. Fellers, William O.: Materials Science, Testing and

Properties for Technicians, Prentice-Hall 1990.

3. Spiegel, F. Xavier: Five experiments in Materials

Science for less than $i0.00, NASA Conference Publication

3151 November 1991 263-265.

4. Spiegel, F. Xavier: Experiments in Materials Science

from Household,Items, NASA Conference Publication 3201

November 1992 373-375.

5. Spiegel, F. Xavier: Inexpensive Materials Science

Demonstrations, NASA Conference Publication 3259 November

1993 119-124.

ACKNOWLEDGEMENT; The author wishes to thank Mary L.

Spiegel for typing this manuscript.

191

I

OPTIMIZING WING DESIGN BY USING

A PIEZOELECTRIC POLYMER

Mukul Kundu

John AdamsHighSchool

SouthBend, Indiana

and

Nikhil K. Kundu

Purdue University

Statewide Technology

2424 California Road

Elkhart, Indiana 46514

Telephone 219-264-3111

AN AFFORDABLE MATERIAL TESTING DEVICE

Nikhil K. Kundu

and

Jerry L. Wickman

College of Applied Sciences and Technology

Department of Industry and Technology

Ball State University

Muncie, Indiana 47306-0255

Telephone 317-285-5648

193
Optimizing Wing Design by Using a Piezoelectric Polymer

Mukul Kundu

John Adams High School

SouthBend, Indiana

Nikhfl K. Kundu

Purdue University

Elkhart, Indiana

SponsoringTeacheratJohnAdamsHighSchoolNevin : E.Longenecker

Objective:

Thisexperimenallows t studenttsolearnhow touseelectroniwictshanelectromechanipolymer cal to

monitor win8 stability. By using thispolymer, changes in air pressure arounda model wing can be detected

and used to determine stable wing designs.

Equipment:

• LM741 orLM1458 OperationalAmplifiers

• CHAMPdigitizerinterface

• Apple He computer

• Wind Tunnel

Introduction:

The principle of airplanelift is based in the design 0fits wings. Thrust is necessary to produce an air flow

aroundthe vehicle so thatlift is achieved. The amount of thrustrequired to lift the plane into the air is

dependent on the wing design and the mass of the vehicle. The lift thatan airplane produces is determined

by the difference in air pressure on the wings' lower and upper sides. This pressure differenceoccurs

because the velocities of the air on the top and the bottom ofthe wing are different.

The relationshipbetweenair velocityand air pressure was firstdiscoveredby DanielBernoulli. BemouUi

observedthat asthevelocityof air increasedthe airpressure decreasedand vice versa. Since the air velocity

above thewing is lfigherthanthe air velocity below the wing, the airpressure is lower and higher

respectively. Iflaminarair flow (asopposed to turbulentairflow) exists, thenthis principlecanbe applied

and liftis produced.

In this experiment, the piezoelectricpolymerpolyvinylidenefluoride(PVDF) was used to measure stability

in several wing designs. Piezoelectricmaterials have the abilityto convert amechanical force into an

electrical pulse and vice versa. The molecules in this polymerare arranged in a zig zag formationwhere two

fluorine atoms and a carbonatomform a dipole which causes a charge redistribution. Likewise two

hydrogen atoms are bonded to a carbon atom which .causesan oppositecharge redistribution (fig 1). When

the film is exposed to a strong DC field,hydrogen and fluorinemolecules align as dipoles. This causes an

electric field polarization to exist within the film. When the dipolesmove, this electric field polarizationwill

produce a voltage which is proportional to the physical displacement.

194
MolecularStructureof PVF2 Th_ PVDFonly generates and electricalpulse when thereis a change in mechanical force on it. Since

PVDFis manufactured in sheets it was easily

attachedto the model wings thatwereplaced in the

wind tunnel. By attaching an amplifier to the

transductive film, it was possible to measure changes

in lift.

elphe lahore - t,_nl_ol_rizect

.:" '_

Studentsconducting this experimentwilllearn about

polyvinylidenefluoride and how to harness its

piez_lectric properties. They will learn elementary

dectroniesiby ass_mblin8 the amplifierneeded with

_ ph_s_-_oJarize_ the PVDF.

Figure l

This experimentdemonstrated an efficient and inexpensivemethodto measure wing stability by using

polyvinylidenefluoride as the primary sensor device. A computerdigitizer was also used to get the

graphical results fromthe PVDF sensor. The procedures required to execute the experiment are listed

below:

• design and constructionof model wings with sensormounted Wing 1

• mounting of model wings in the wind tunnel

• design andconstructionof amplifier circuitand data collection

Design and constructionof model wings with sensor mounted: Wing2

Fourdifferentwing designs wereused (fig 2). ( _- [ 2__

Procedure:

_/ing3

• .Thewings were constructedwith a sturdy flexibleplastic sheet. The sheet

was shaped into the design for the wings and then forcedin shape with

cellophane tape and supported by holders at the ends. Balsa wooden mounts k2_Z>

were attachedto the ends of thewing formounting (fig 3). Wing 4

• Thesensorwas attachedto the undersideof the wing forliftmeasurement, f jJ" _,,-_'_-_

ThePVDF was attachedwith glue to the plastic.Electrodeswereattached to

the ends of the film. \'lf

Figure 2

195
• Tomake contactwith the PVDF sensor

aluminumfoilwasplacedbetweenthefilmand

the wing at one end and over the film on the

other end. Rubber bands were placed over the

overlap of the PVDF and aluminum to insure

contact. The aluminum foil was then attached

• to wires which ledto the amplifier.

Mountingof modelwings in the wind tunnel

• A low speed,indraflwind tunnel was used to

providethe laminarairflow around thewings.

Thewindtunnelis 22 feetlong with a test area

of 10in. * 10in. * 60in. Theratioof the

contractionsectionto the testsection is 1:20

with the diffusersectionsloped at an angle of 7

degrees.Windspeedsrangefrom0 to 20.1

m/sec (45 mph) andis producedby twovariablespeedfans.

Figure 3

• A mountingstandwas constructed j

with walnutwood. The standhad "

rubberfeetunderneathitto increase

frictionbetween it andthe wind tunnel. _,

Thestand was created so thatwing i "_

models could be mounted and

dismountedquickly. Thestandwas

equippedwith a compassso the angle

of the wing could be measured.

• ,Thestand with the model wing was

placed in thewind tunnelwitha "**

weightplacedon a lowerpart ofthe

stand so thatthewing remained

stationary.Wireswere connectedwith

alligatorclipsto the aJuminumfoil.

Thismade it easy to switch wing .................

models in thewind tunnel (fig 4).

Figure4

196
Design and constructionof amplifier circuit and data collection:

• The amplifiercircuit(fig 5) is used so thatthe pulses generatedby the PVDF axeable to be read by the

CHAMP analogto digitalconverterinterface.

• TheCHAMP was connectedto anAppleHe computer.Thedatawas then transferredto an IBM

compatiblecomputerandonto a spreadsheetwhich was usedto generatethe graphs.

100 kQ 1 kfl

. _ 220 n

_/_ _ Outpu_

14_8

_LAmp_er Stage 220 n

| D.C. Offset Stage

IN k_

Figure 5

Results:

Bemoulli's principleoccursin win8 mechanicsbecause the distanceairtravels above a wing is morethan

the distanceit tm_b underneath a wing. Thismeansthattheratio of thelengthon the topa wingto the

lengthunderneathcanbe usedto comparelift of wings. Thelift of the fourmodelwings aregraphedbelow

(fig 6). Thehigher theratiothemoreliftthewingcanproduce.

TheCHAMP analogto digitalconverterallowsthe electricpulses producedbythe PVDF onthe underside

of _e wing to be storedon a computer. By using a spreadsheet,graphswere createdforeachwingwith

approximately45 MPH air flow (fig 8). SincePVDF only createsa pulse when a change in liftoccurs,the

graphsarealternatingwaves. To attaina qualitativevalue, the voltage rangesforeachwing was compared

(fig 7). Thegreaterthe range,the moreunstable the wing is.

197
5 4.6

4.5 4.4

4 _4.2

4

3.5

> > 3.8

3 3.6

2.5 3.4

Samples(#) Samples(#)

Fisum 8a: Win 8 1 Figure 8b: Win8 2

10 5.1

9 4.9

8

.-, 7

>-_.. _ 4.7

6 =4.5

_j 4 _4.3

> 3 > 4.1

2

1 3.9

0 3.7

Samples(#) Samples(#)

Figure 8c: Wi_8 3 Figure 8d: Wia8 4

198
Conclusions:

Thestabilitytests indicatedthatwing 4 was the most stableofthe models. However,the liftfromwing 4

was lower thanthe otherdesigns. Thisis becausewing 4 hada "symmetrical"shape where the distance

above the wing was veryclose to the distancebelow it. Itssmallthicknessandits symmetricalshapewas

responsiblefor the high stability.

Stabilityforwing 1wassecondbest. The _ fromthiswingwas alsosecondbest. The"streamlintyp e ical"

shapeof thiswinghelpreducedragandproducea substantialamountofliftwitha largeamountofstability.

Stability forwing 2 was elose to that ofwing 1. Howrcer, the liftof the wing was _mid_Tably more than

that of wing 1. This is because the "typical" shape wing boasts a largerthickness which increasesthe

distance above the wing. This will produce considerable stabilityand high amounts of lift.

Stability forwing 3 was eighttimes worsethan the other models. This model was designed with the

purpose to indicatea low stabilityrating. This "tear drop" shape produces a low amount of liftand is useful

forcomparison to the othermodels.

199

An Affordable Material Testing Device

Nikhil K. Kundu

Purdue University

Elkhart, Indiana

Jerry L. Wickman

Ball State University

Muncie, Indiana

Participating Students: R. Clark, S. Stump, T. Flanders, J. Wamer

Introduction:

One of the thrusts in engineering technology education is to combine a laboratory experience with the

theoretical portion of the coursework. Experimental demonstration is an important factor in creating

interest and motivation in learning. Most of the time budgetary limitation does not permit the purchase of

expensive laboratory equipment. The project presented here is an effort to design an universal testing

device for the strength of materials laboratory at the minimum cost.

This project was assigned to a group of four students as a partial requirement for a sophomore level

strength of materials course. The paper describes the construction of a testing apparatus for a number of

experiments such as tensile test, punching shear test, column buckling, and spring rate.

The device consists of a metal frame made of two channel iron with one asthe base and the other at the top

supported by four all thread rods for height adjustment (fig 1). A hand operated hydraulic power pack is

used to operate a cylinder that applies force on test samples. Applied force is determined by multiplying

the pressure recorded with the effective area of the hydraulic cylinder. Accessories include a holding

fixture for punching shear samples and two cup shaped holder for column buckling, and two jaws for

holding samples for tensile tests.

After brief description of each experimental procedure and data collection the results are graphically

reproduced at the end of this paper. This device is meant to be used for classroom demonstration and

laboratory exercises. It is lightweight,simple and affordable.

This testing device will perform the following experiments:

• Punching Shear

• Spring Rate

• Tensile Test

• Beam Bending

• Column Buckling

201
ITEM SlZ__EE MATERIAL QTY PRICE

A1 C 6 x 10.5 x 14" Am.Std.Steel 2 $0.69/Lb.

Channel

A2 314"- 10 x 24" Steel Thd. Rod 4 $4.50 ea.

A3 3/4" - 10 Steel Zink Nuts 20 $0.40 ea.

A4 1" x 2" x 15" Aluminum 6063 1 $51.14/8'

A5 62205Kll MF2 Dbl. Act. Hyd. Cyl. 1 $230.88

If everything was purchased: Total Cost $898.71

I_'JG -- I

202
SHEAR PUNCH

Figure 2 Figure 3

Punching Shear (fig2 & 3):

The purposeof thisexperimentisto determinethe ultimateshearstrengthofvariousspecimens.

Procedure:

• Measure and record all specimen thicknesses

• Measure punch and die diameters

• Estimate force required to punch specimens

• Install punch and die and proper shaft on cylinder

• Insert specimen between punch and die

• Set directional valve to extend position

• Apply force with the hand pump till shear failure

• Lift punch out of specimen and die

• Determine maximum shear strength for all specimens

See figure 12 for the graph.

203
B1 1 1/2"dia. x 2" Ig. 6061 Aluminum 1 $2.55

B2 1 1/2"dia. x 2" Ig. 6061 Aluminum 1. $2.55

l_';_.[ lure 4. 83 7/8" washer Zinc plated steel l/net 51b $8.11

134 3J8" bolt Zinc plated steel llnet 100

TOTAL $25.31

Spring Rate Test (fig 4 & 5):

The purpose of this experiment is to find rate of Figure 5

springs with various geometry.

Procedure:

• Find the inside and the outside diameter of each spring

• Measure the wire diameter of each spring

• Find free length of each spring

• Attach the upper half of the spring test fixture to the hydraulic cylinder and the lower half to the

adjustable cross member.

• Place a spring into the fixture and slowly lower the hydraulic cylinder. Make sure that the spring sets

inside of the recess of the fixture. Apply enough force to hold the spring in place.

• Set a dial indicator on the top or bottom of the upper spring fixture to measure the amount of

deflection.

See figure 13 for the graph.

204
Figure 6 Figure 7

Tensile Test (fig 6 & 7):

The purpose of this experiment is to obtain experimental data for a stress strain diagram.

Procedure:

• Attach the upper and lowerjaws (fig 7) to the fixture and adjust the distance between the jaws if

required.

• Using the dial calipers and micrometers, determine measurements of the sample.

• Place the sample in the tensile testing fixture. Make sure that it is properly aligned.

• Slowly increase the pressure with the hand pump, thereby increasing tension on the sample.

• Continue to increase the pressure and incrementally record your data until the sample ruptures.

• After the sample has ruptured remove it fromthe fixture, place the fractured ends together, measure

and record the length.

See figure 14 for the graph.

205
BEAM BENDING

[ ....... -]

I +ooo ,1

I" o+oo I

_.13 ALL I TEI_

E1 1"x1"x18 gaJc2T' lg. Steel sq. tube I $2.87

'- ! & F._2 1"xl"x18 ga.xlT _g. Steel sq. fLOe 1 $1.50

-- E3 I I/2_ I t/Z'b_ I/'2" I_ Stee_ar_le 4 $,4,70

E4 7/16" nut Zinc plated steed lh_et 100 $7.56

F_5 1/8 Mdd-steel 1/5 Lb $850

TOTAL $25.13

Figure 8 Figure 9

Beam Bending (Flexural Strain) Test (Fig 8 & 9):

The purpose of this experiment is to determine flexural strain in a beam. Flexural strain is directly related

to the bending moment and beam geometry.

Procedure:

• Attach the beam bending fixtures to the base of the testing device and the hydraulic cylinder.

• Place the specimen on the fixtures (Fig. 9) so that it is centered and in contact with four points on the

fixture.

• Set the dial indicator with modified arm extension in place to measure the beam deflection once a

compressive force applied with the help of the hand pump.

• Read and record the pressure gage and the dial indicator.

See figure 15 for the graph.

206
COLUMN BUCKLING

Figure 10 Figure 11

Column Buckling Test (fig. 10 & 11):

The purpose of this experiment is to determine the critical buckling load for slender columns.

Procedure:

• Measure and record the diameter and length of the specimen

• Oil both ends of the rod - insert into top seat.

• Extend cylinder rod using the hand pump.

• Continue to lower rod until seats hold the specimen rod.

• Slowly extend the cylinder rod - observe the specimen rod for bow and read the pressure.

• Calculate the critical load

207
Graphs:

Ultimate Stress vs. Material Thickness

45000

m

_" 40000

35000 ----m---- UILStress

--4--- Calculatedstress

30000

E

_ 25000

20000 ! _ i i i i

0.03 0.04 0.05 0.06 0.07 0.08 0.09

Matedal Thickness (in)

Figure 12 - Punch Shear: ultimate shear stress vs. material thickness

St_ng_teO-_

i)

• I

In , ,

=I,* =

0

0 _(]6 0.1 0.1S O_ 0._

De_e_m(inches)

Figure 13- SpringRate: loadvs. deflectionof twosamplesprings

208
0.2%Of_et

8O0OO

7oooo / _,

_oooo /_/ \, // _'50000

40000 °

30000 /

,,, /

20000 /

10000 "/

o_

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Displacement{in)

Figure 14 -Tensile: stress vs. displacement curve

BeamBending

9(

• 811 /

3Q _

'°0 i

0 0005 001 0015 0.2 002S

Deflection, (Inches)

Figure 15 - Beam Bending: load vs. beam deflection

209

I

PHOTOCATALYTIC DESTRUCTION

OF AN ORGANIC DYE

USING TiO2

Kim Giglio

John Bowling

Ben Hutchinson

David Green

Natural Science Division

Pepperdine University

24255 Pacific Coast Highway

Malibu, California 90263

Telephone 310-456-4321

J !

211
212
Photocatalytic Destruction of an Organic Dye Using TiO2

KimGiglio,JolmBowling,Ben Hutchinson,DavidGreen

Natural ScienceDivision

PepperdineUniversity

Malibu,California

Key Words: Photocatalytic, Solar, Titanium Dioxide

P. erequisite Knowledge: Knowledgeof basic semiconductorband theory and spectrophotometric

techniquesare helpfulin understandingand pertbrrningthe experiment.

Objective: To observe the effect ofa photocatalystactivatedby solar energyappliedin the presence

of a dye solution.

Equipment:

I. Basicglassware including500 mL round-bottomflask, gas spargingtube, 1 cm x 20 cm drying

columns,500 mL gas washingbottle

2. Aquariumair pump

3. Magnetic stirrer

4. 10 mL plastic syringe

5. Bausch& Lomb Spectronic-20UV-visiblespectrophotometer(or similarinstrument)and

appropriate cells

6. Time measuringdevice

7. Soda Lime(P. K. Morgan Instrument Co.)

8. Desiccant(such as DrieriteTM)

9. 90%-saturatedbariumhydroxide solution

10.0.45 gm nylon-membranesyringefilters(Gelman Sciences,Inc.)

Introduction:

Titaniumdioxide, TiO2, is used by college students on a regularbasis whetherthey are aware of it or

not. Widely known asthe principlepigmentin whitepaint, TiO2maybe found as close as their eyelids

and noses in the form of cosmetics and sunblock.

TiO2 hasrecently attracted scientificattentiondue to photocatalyticpropertiesin its colloidaland

immobilizedphases. Although the "chalking"of paint containingTiO2 providedan early clue and

213
sparked interest in its use as a photocatalyst(l), this property hasfound applicationrecentlyin organic

synthesis(2)and has been investigatedas an environmentallycleanmethod to destroy organicsin

water(3,4).

Colloidal anatase-TiO2 is a semiconductor with a band-gap energy of 3.2eV which, when illuminated

by light with wavelengths less than 360 run will cause photoexcitation of the TiO2 producing an

electron and a positive hole, h+. In the presence ofdioxygen and water, hydroxy radicals (OH') are

produced. In a solution containing an organic molecule such as a dye, the OH. will react with the

molecule to produce carbon dioxide.

In this experiment,students use solar energyto activate an aqueous slurryof TiO2 that mineralizesan

organic dye to carbon dioxide. Since the solar energy spectrumpossesses wavelengthsbelow 360 nm,

although at low intensityat the Earth's surface, the experimentdescribedhere can be performed in

naturalsunlight.

Procedure:

Apparatus:

I o,1

Figure 1. Schematicdiagramof the reactor system, a. airpump;b. drying column;c. soda limecolumn;d. 500 mL

round-bottom flask; e. 10 mL samplingsyringe;f. gas

washingbottle; g. magnetic stirrer.

A schematicof the reactor systemisshown inFigure 1. The reactionvessel is a 500 mL, 3-neck round

bottom flask (Figure ld). Ground-glassjoints are securedwith plasticclipsavailablefromFisher

ScientificCo. Air,which is pumpedthrough the systemusing a Whisper-500TM aquariumair-pump

(figure la), is dried through a 1cm x 20 cm tube containingdesiccant and the CO2removedusing a

similartube containing"indicating"soda lime (P. K. Morgan Instrument Co.), Figure lc. All connections are made with short lengthsof latex tubing and securedwith copper wire. The dry, CO2-freeair

is introduced into the reactionvessel through a mediumporosity,sintered-glassspargingtube attached

through one of the necks of the flask. A 6 mmglasstube isinserted through a standard-taper 19/22

214
thermometerfittingforthecollectionof theeffluentgases. Theglasstubingisconnectedto a 500mL

gas-washingbottlecontaining250mLof 90%-saturatedbariumhydroxide(Figure1f)fittedwitha

coarsesintered-glassbubbler.

Samplesare collectedviaa 3.5mmo.d.glasscapillaryextendedintothe solutionthrougha #00oneholerubberstopperfittedintoa standard-taper19/22thermometerfitting. Approximately8 cmof 1/8"

o.d.TygonTM tubingisconnectedto the maleendofa Luer-lockstopcockanda 10mLsyringeis

attachedto thestopcock.Theentireapparatusis placedon a corkringforsupportandthesolution

stirredwitha magnetic stirrer.

Preparation of Solutions:

A 100 ppm stock solution of malachite green oxalate (MG) (J. T. Baker Chemical Co.) is prepared by

dissolving 0.100 g of solid MG in a 1L volumetric flask, diluting to the mark with water, and mi:dng

well. The stock solution may be shared among many groups of students. Aliquots of 2, 5, 8, 10 mL

aretransferredto 100mLvolumetricflasksanddilutedto givefinalconcentrationsof2, 5, 8, 10ppm

for constructionof a Beer'sLawcalibrationplot. Simulatedpollutedwaterispreparedbydilutinga 25

mLaliquotofstockMGsolutionto 250mLin a volumetricflaskto givea concentrationof l0 ppm.

Mr-free90%-saturatedsolutionofBa(OH)2usedforCO2-analysisispreparedbystirringandheatinga

mixtureof 30g ofsolidbariumhydroxidewith500mLofwateruntilthe solidcompletelydissolves.

Thesolutionneednotbe heatedabove35-40°C.Thesolutionisallowedto coolto roomtemperature

in a closedcontainerto protectitfi'omtheair. Whenthe solutioniscool,-450 mLofthe clear

solution is decanted into another bottle followed by 50 mL of boiled and cooled deionized water The

amount of barium hydroxide solution is sufficient for two complete runs of the experiment.

l l i i

2,0 ' ' ' ' ' '

1.5 .-

/.. -

Q /

1.5 _ /...

£ 1.0 ."

_ .

1.0 i II1,,

< / _ ."

o 0.5

0.5 _ "/

I''I', f II

.o \ •

rJ e.o._Q_" //

o.o 0.0 ,.•

I I I I I f I 1 I I I

300 40o 5oo 600 7oo 0 2 4 6 8 10

WavelenglWnm Concentration/ppm

Figure2. UV-visibleabsorbancespec- Figure3. Beer'sLawcalibrationplot of

trumof MG. absorbanceat610nmvs. concentration

forMG.

215
Visible Light Spectrum and Beer's Law Calibration Plot

A Bausch & Lomb Spectronic-20 spectrophotometer may be used for the acquiring the UV-visible

spectrum from 350 to 650 rimin 20 nm intervals on the 10 ppm MG solution using water as a reference

(Figure 2). The Beer's Law calibration plot is prepared at 610 nm using the standard dilutions (Figure

3). If the wavelength of maximum absorbance differs from 610 nm, the wavelength measured on the

particular instrument should be used.

Photocatalytic Reactor Set-Up and Acquisition of Samples

In order to isolate the effect of TiO2,three different experimentaltreatmentsare used to study the

decompositionreaction with MG; 1) a control experimentin whichthe solution isin contact with the

catalystbut kept in the dark, 2) a second control experimentin whichthe solution is exposed to

sunlightin the absenceof the catalyst, and 3) conditionsin whichthe solutionis exposed to sunlightin

the presence of the catalyst.

Set up the reaction systemas shown inFigure 1. In experiments1) and 3) a 0.1% suspensionof TiO2

(0.25gTiOzper 250 mL solution)is used with a magneticstirringbar to keep the catalystsuspended

The reaction vessel is completelycovered with aluminumfoilto prevent exposure to light prior to

acquisitionof the firstsample. Place about 250 mLof the Ba(OH)2 solutioninto the gas washing

bottle and attach a short piece of latex tubing to the gas washingbottle fromthe reactionvessel as

shown.

Experimentsin the sunlightare performedduring the earlyafternoon and initiatedby removingthe toil

immediatelyalter taking a 6 mL sample of the solution. Take additionalsamples every 15 minutes

throughout the experiment, place in labeledtest tubes, and protect fromlight with aluminumfoil.

Centrifuge samplesfor about 5 min and remove the remainingsuspendedTiO2by filtrationusing0.45

lampore-size nylon syringe-filter(GelmanSciences,Inc.).

The effluentair containingCOz produced in the decompositionreaction passingthrough the gas

washing bottle forms a precipitateof BaCO3. The white solidBaCO3is collected by vacuumfiltration

on a fine, sinteredglass filter, driedto constant weight in a 105°Coven for one hour, andweighed.

The mass of CO2 produced is determinedfrom the mass ofBaCO3 tbrmed.

Analysis of Data:

Compare the quantity of CO2 produced to the theoreticalmass of CO2which is calculatedfromthe

mass of MG placed in the reactionvessel. The concentrationof MGfor each sampleis calculatedfrom

the equation of the Beer's Law calibrationline. On one graph plot the concentration of MGvs. time

216
for each of the experiments.

Effect of the Photocatalyst TiO2:

Based on the results in the three experiments comment andexplain your reasoning on the effect of"solar

energy and the photocatalyst TiO2 in the reaction. Calculate the % yield of CO2.

Notes to Instructor:

1. The % CO2 found willbe slightlylow since some solutionisremovedfor samplingduring the

experiment,but the error is lessthan 10%.

2. We suggest the zero-timesamplesbe taken fromthe reactionvessel after the additionof the

catalyst and just priorto exposingthe vesselto the sunlight.

3. The initialconcentrationmeasured spectroscopicallywas consistentlylower than the calculated

concentration based on massbecause of smallamountsof stray lightand adsorptionof the d_e to

the surface of the catalyst.

4. A team of at least three students isrecommendedtbr the experimentwhich require shouldbe

performed over two laboratory periods. The firstto prepare solutions,set-up and test the rea,::or

system, and performone of the control experiments.

5. This basic experimentcan be extended by usingother dyes and/orperforminga kinetic anal_s_s

depending on the level of the students chemistrybackground.

References:

1. Kennedy, D. g.: Trans. Far. Soc. vol. 54, 1958, pp. 119.

2. Fox, M. A.: Acc. Chem. Res. 1983, vol. 16, pp. 1242.

3. Ollis, D. G.: Environ. Sci. Technol. vol. 19, 1985, pp. 480.

4. Schiavello, M.Ed.: NATOAdv. Studybtst. Ser. 1988, pp. 237.

217

ULTRASONIC WELDING OF RECYCLED HIGH

DENSITY POLYETHYLENE (HDPE)

Ping Liu

and

Tommy L. Waskom

School of Technology

Eastern Illinois University

101 Klehm Hall

Charleston, Illinois 61920

Telephone 217-581-6267

219
22O
Ultrasonic Welding of Recycled High Density Polyethylene (HDPE)

Ping Liu and Tommy L. Waskom

School of Technology

Eastern Illinois University

Charleston, IL 61920

KEY WORDS: ultrasonic welding, high density polyethylene, milk container, ASTM

standards, tensile test, welding strength.

PREREQUISITE KNOWLEDGE: The students should understand the fundamentals

of ultrasonic welding of thermoplastics and mechanical property testing of materials. The

ability to use ASTM standards is also necessary for designing material test specimens and

testing procedures.

OBJECTIVES: To understand the concept of thermoplastic ultrasonic welding and

applications in industry.

EQUIPMENT AND SUPPLIES:

1. Recycled plastic one-gallon milk containers

2. Ultrasonic welding system

3. Steel rules and compass (or a specimen template)

4. Scissors

5. Tensile test machine.

INTRODUCTION:

Ultrasonicassembly is a fast, clean and efficient method of assembling or processing

rigid thermoplastic parts, films or synthetic fabrics. Various ultrasonic assembly techniques

are used by all segments of industry to join plastic to plastic, plastic to metal parts or other

non-plasticmaterial. Ultrasonicweldingcan replace or precludethe use of solvent, adhesives,

mechanical fasteners, or other consumable. Ultrasonic welding is one of the techniques

commonly used in industry.

The basicprinciple of ultrasonicwelding is presented as follows. When two pieces of

thermoplastics are vibrated together fast enough with appropriate amplitude, heat will be

developed. As a result, a flow of plastic will occur at the joint interface. The method can

provide strong and hermetically sealed components at a high production rate.

Figure 1 illustrates the principle of ultrasonic welder. A solid-state power supply

converts 50/60 Hz current to 20 kHz or 40 kHz electrical energy. This high frequency

electrical energy is supplied to the converter that changes electrical energy into mechanical

vibratory energy at ultrasonic frequencies. The vibratory energy is then transmitted through

an amplitude-modifying device called booster to the horn. The horn is an acoustic tool that

transfers this vibratory energy directly to the parts being welded.

The variables in theultrasonicweldinginclude pressure, trigger force, weld time, hold

221
time, after-burst (AB) delayand AB time. The characteristics of thermoplastics, such as melt

temperature, modulus of elasticity and structure, determine the energy requirements of the

weld. Optimum parameters can be identified through experiments according to the energy

requirements.

Power Supply

20/40 kHz 60 Hz

Converter Booster Horn

Figure 1 Principle of ultrasonicweldingequipment(CourtesyBransonUltrasonicsCorp.).

222
PROCEDURE:

1. Collect,clean anddryrecycledplasticmilk containers.

2. Cutfiatsheetsof highdensitypolyethylenefromthe milkcontainers. The sheetsize

is approximately127 × 127mm (5 × 5 in.).

3. Set parametersof the ultrasonicweldingsystemas follows:

Air pressure: 172kPa (25 psi)

Triggerforce: 178N (40 lb., dial reading 5)

Down speed: Dial reading 5

Hold time: 0.42 s

Weld time: Variable, 0.21-0.33 s

AB delay: 0.25 s

AB time 0.05 s

4. Weld the plastic sheetsto obtainproper quality.

5. Cut the tensile test specimensfrom the weldedplastics accordingto dimensions

specifiedby ASTM standards[1], asshownin Figure2.

6. Test the tensile strengthof the weldingand evaluatethe effectivenessof welding

SL 33 rnm ._ _,

80 mm

ll5mm

Figure 2 Dimensions of the tensile test specimen per ASTM standard D 638M-89.

223
SAMPLE DATA SHEETS

The data in the following table are tensile test results of welding joints formed with

different weld time. All other parameters were identical.

Welding Time (s) Peak Load N (lb.)

0.21 52 N (11.7 lb.)

0.24 817 N (183.8 lb.)

0.27 544 N (122.4 lb.)

0.30 426 N (95.9 lb.)

0.33 279 N (62.7 lb.)

INSTRUCTOR NOTES:

Students can perform investigative studies of the effect of welding parameters such

as weld time on the weld quality. Figure 3 shows variation of peak load with ultrasonic

welding time for recycled high density polyethylene welds. All other processing

parameters were kept the same as those showed in step 3 of procedure section. Initially,

the welding strength increased with the welding time up to a maximum at a weld time of

0.24-0.25 seconds. Then, the welding strength declined with increased weld time. It is

concluded that the weld time of 0.24-0.25 second will provide the optimum welding

strength for the thickness of high density polyethylene.

Dueto the irregularweld section,it is a better choiceto evaluatethe peak loadthan

shear stressfor practicalweldingapplication.

REFERENCES:

1. ASTM: 1993 Annual Book of ASTM Standards, Vol. 8.01 Plastics (I),

American Society for Testing and Materials, Philadelphia, 1993.

2. M. L. Berins: SPI Plastics Engineering Handbook (5th ed.), Van Nostrand

Reinhold, New York, 1991.

3. Branson Ultrasonics Corp.: Ultrasonic Plastic Assembly, 1994.

SOURCES OF SUPPLIES:

The high density polyethylene was obtained from milk containers recycledby

faculty and students without any cost.

224
ACKNOWLEDGMENT:

The donation of the ultrasonic plastic welder from BransonUltrasonic Corporation,

Danbury, CT is greatly appreciated.

Part of the financialsupportfor this project is from the Illinois Departmentof

Energy and NaturalResources throughthe Office of Solid WasteResearchat the

University of Illinois at Urbana-Champaign. Another part of the material is based upon

work supportedby the National Science FoundationunderGrant No. DUE-9350629.

900.............................................................................................................................

I _ i I I !

800.......i...../_-.i ......_........_...... - i........ i /..._....N.. _ _ i

....700 ............. i'"; ! _ ........... i............. i............... i.......... :z 600

--- -......i"7....T.....!-N-fi........i-......!........ "cI /

500 i i

-_ 400

0J 300

200 ./-___! .....

loo....;/-_ ....._..........

O' ' I , I , I , I , I , I ,

0.20 0.22 0.24 0.26 0.28 0.30 0.32 0.34

WeldTime (s)

Figure 3 Variation of peak load with ultrasonic welding time for recycled high density

polyethylene.

225

INTRODUCTION TO CONTINUOUS FIBER

CERAMIC COMPOSITES

William G. Long

Babcock & Wilcox Co.

Lynchburg Research Center

Mt. Athos Road

P. O. Box 11165

Lynchburg, Virginia 24506-1165

Telephone 804-522-5716

227
228
INTRODUCTION TO 

CONTINUOUS FIBER 

CERAMIC COMPOSITES 

WILLIAM G. LONG 

BABCOCK & WILCOX 
Examples of Composites in Nature 

Wood 

Cellulose fiber in a resin matrix 

Probably the oldest, cheapest, and most reliable composite 

material 

Limited in fracture stress level, temperature and geometry 

Bone 

Collagen fibers provide toughness and flexibility 

WGL 911 2/94\ 
Ceramics Have Excellent 

High-Temperature Properties 

Strength to 1300 - 1400°C (2372 - 2552°F) 

Corrosion resistance 

4 Select from a variety of materials that include: 

Carbides 

Nitrides 

Oxides 
Monolithic Ceramics Have 

Limitations 

4 Fail in brittle fracture 

4 Reliability suspect 

4 Thermal and mechanical shock properties poor 

WGL 9/12/94 
-- - 

Definition of Terms 

Fiber Normally used in a multi-filament tow, with 

300 - 1000 filaments per tow. Each filament 

typically is about 10 microns diameter. Fibers 

may be carbide, oxide, or nitride. 

Matrix Body of the composite that contains the fiber 

reinforcement 

Interface Area in a composite where the fibers and matrix 

meet. The chemistry of the interface is critical to 

performance at temperature, and will control the 

pullout of the fiber at fracture. 

Fiber coating Filaments are coated to produce an interface 

that allows pullout and protects the fiber from 

chemical attack 
CFCCs - An Engineered Solution 

Fiber reinforcement retards crack propagation and 

provides mechanical support at high stress levels. 

The individual fibers must fail before fracture can 

WGL 911 2/94\ 
Application Specific Properties 

Like other composites, CFCCs offer great potential 

to customize materials for specific applications 

based on appropriate choices of constituents and 

design of fiber architectures 

Directional properties 

Controlled failure modes 

Tailored environmental stability 
Potential Operating Temperature Regimes 

Based on Corrosion in Waste Incinerators 

Temperature 

(" F) 

FR Plastics Corrosion- Superalloys Advanced 

Resistant Ceramics and 

Alloys Ceramic 

Composites WG L 911 2/94\ 
CFCC Targets 

Heat Exchangers 

Performance targets 

Component temperatures to 1200°C (2192 OF) 

Proportional limit (matrix microcracking) >41 MPa (>6 kpsi) 

Thermal conductivity >8.6 w/mK 

Thermal shock resistance >330K in 5 minutes 

Permeability negligible (to be determined) 

Lifetimes of 24,000 hours to 10 years 

Economic target 

~$50 per foot 
CFCC Targets 

Gas Turbine Components 

Performance targets 

@ Component temperatures to -1300°C (2372°F) 

@ No film air cooling 

@ Lifetimes of 24,000 hours 

Economic target 

@ Ceramic hardware should be 1 3 - 5 times current metal 

hardware 
DOE CFCC Program Components 

Porous radiant burners 

Surface mat 

Reverberatory screen 

Atmospheric-pressure and high-pressure heat 

exchangers 

Tubes 

Elbows 

Manifolds 

Hot furnace fans 

Hot gas filters (for coal combustion and chemical 

processes) 

Candle filters 

Tubular filters WGL 911 2/94\ 
DOE CFCC Program Components (contit.) 

Gas turbines (large and small) 

Combustor liners 

Turbine tip shrouds 

Turbine blades 

Vanes 

Blisks (bladed discs) 

Hot gas transfer pipes 

W Radiant burner tubes 

Immersion heaters 

Boiler components 

Diesel engine valve guides and piston rings 

Steam reformer tubes 

W Containment shell for sealless chemical pump WGL9/1U%\ 
Continuous Fiber Ceramic Composites 

Retain Strength at Elevated Temperatures 

WGL 9/12l94\ 
CFCC Applications in MET' 

Advanced Power Systems 
Westinghouse Candle Fi ter Svste r%' 

...... ....... ;.. ................... ,, ,$ .% :< A:..:. .... .,... .A. ...... 

WGL 911 2/94\ 
Filament Winding a Turbine Combustor 

WGL 911 2/94\ 
DESIGNING WITH CONTINUOUS FIBER

CERAMIC COMPOSITES

Kenneth L. Reifsnider

Virginia Polytechnic Institute and State University

Virginia Institute of Materials Systems

120 Patton Hall

Blacksburg, Virginia 24061-0219

Telephone 703-231-5316

245
!i!_!!!iii!!!iii_iiiiiiiii

246
~omd~naaous Fiber 

Ceramic Composites 

Ken Reifsnider 

Materials Response Group, Virginia Polytechnic Institute & State University 
Comparative Utility 

I Manufacturing cost 

1 

Corrosion resistance 

Material cost 

Durability 

Knowledge base 

Designldata base 

Polymer 

Metal 

Ceramic - 

Polymer 

Metal 

Ceramic 

Polymer 

Metal 

Ceramic 

Polymer 

Metal 

Ceramic 

Polymer 

Metal 

Ceramic - 

Polymer 

~eial 

Ceramic 

Materials Response Group, Virginia Polytechnic Institute & State University 
Comparative Utility 

Thermal expansion 

Use temperature 

Thermal conductivity 

Product cost 

I Polymer 

Metal 

Ceramic Specific stiffness 

Polymer 

Metal 

Ceramic Specific strength 

Polymer 

Metal 

Ceramic 

Polymer 

Metal 

Ceramic 

Polymer 

Metal 

Ceramic 

Polymer 

Metal 

Ceramic 

Materials Response Group, Virginia Polytechnic Institute & State University 
- if! i i Ceramic Matrix Composites :. i 

. - 

Applications - 

; -> Gas turbines - liners, vanes, shrouds, blades 

-> Radiant burners - tubes, combustors 

-, Heat exchangers - tubes, headers, manifolds 

-> Electronic components - boards, elements, 

sensors, fiber optic devices 

-> Engines - power transfer, exhaustlair 

transfer systems 

-> Hot gas filters - engines, power plants 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ill Ceramic Matrix Composites 

-> Steel soaking pits 

-> Aluminum remelt furnaces 

-> Glass melting furnaces 

-> Recycling facilities 

I 

Materials Response Group, Virginia Polytechnic Institute & State University 

Manufacturing industry applications - 
111 Ceramic Matrix Composites 

-r Engines - 10-35 percent fuel savings 

I 

-> Heat exchangers - recovery of large part of 

Projected advantages = 

the 25 to 65 percent heat loss generated 

by high temperature combustion systems 

Materials Response Group, ~irginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

Flexural strength, Hardness Fracture toughness, Maximum use Younp's modulus*, 

Material MPa' (Vlcken), GPa' MPa mTR temperature, OC GPa End uses 

I 

Alumina 310 17 4 1200 31 0 Wear parts, cutting tools 

Silicon carbide 690 22.4 4 2000 450 Wear parts, cutting tools, 

heat exchangers 

Silicon nitride 925 15.9 5.5 1400 31 5 Wear parts, automotive engine applications 

Zirconia 1440 12.8 8.5 800 220 Cutting tools, wear parts, 

experimental heat engines 

Tool steel 5500 10 98 700 21 0 Cutting tools, wear parts 

-> Properties and end uses of advanced ceramics 

* Megapascals. 

bGigapascals. 

cYoung's modulus defines the ratlo between stress and strain and is an indicator of the elasticity of a material. 

CHEMTECH NOVEMBER 1993 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I I Ceramic Matrix Composites 

Table 3. Various current and potential applications of ASC 

and application requirements 

I 

Industry Application Application requirements Table2. Estimated size of current and 

Machine tool Cutting tools Wear and corrosion resistance, projected U.S. markets for ASC 

Bearings minimum lubrication requirements (in millions of dollars) (6) 

Wire drawing dies 

-> Advanced structural composites; applications 

Petrochemical Seals Energy-efficient heat regeneration 

Valves 

Pump impellers 

Heat exchangers 

Automotive Turbocharger rotors Light-weight, high-temperature, 

Push rod tips corrosion and wear resistance 

Rocker arms 

Cylinder liners 

Defense Gun liners Light -weight, strength, corrosion, 

Ceramic armor and high- temperature resistance 

and markets 

Wear parts 

Cutting tool inserts 

Bearings 

Bioceramics 

Heat exchangers 

Autornotive/heat engine 

Aerospace, defense 

CHEMTECH NOVEMBER 1993 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

I I -> Projected development of ceramic cc 

I 

Mililary applications B4C Armor &lings 6earlnQs Diesels TurblMs Radomss lsobted componants 

Wear parts 

CUIIII~ IWIS 

I Bearings I AIzO, SbN4 ~llttq omm men^ I 

SIC Si,N Cornpasla A1201 S13N4-BN 

A12°3 A1203 coating si,~, A124 -SIC Advanced materlak 

L 

B~oceramics I FDA hip 0imopadlc Mvanced 

approval and dental matetiah 

Heal exchangers RruprataQ ROW Tubular CogsnenUon Fixad 

lurnacas Mlllla~ lnduslrkl boundan 

Advanced curlslruclron products Ulamlcally I bonded ceramla Composlta 

I Diesel aulomolivs 

k~lomot~vs lurbrne 

1 O2 sensors Ekclroch~lion Na-S bamry Fuel al 0. oumn I 1 -.rus1 orl liner 

b~ger piston p~n 

isolated rls 

~num~efingine components 

Isolated 

cornoonenb I ' J 

Cuttlnp Turbine colnponenls Mhimwnzooled 

IWIS dinsel c~npo~nls 

Flgurr 1. E:llmrlts lor lmplrmtnlrllon ol ctnmic componrnl: in :lruclunl rpplic~llon cale~odlt (4). 

41 CMUTECH NOVEMBER 1993 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I 

Task 1 Applications Assesstnerzt 

Solar Tzirbines - Benefits 

Ceramic Matrix Composites 

I 

Energy Savings - Fleet of Metallic end Ceramic Engines to Meet Predicted Needs 

-r Application examples - benefits 

Year 

Environmental Savings - Comparative NOx Emissions in TonslYear for Metalllc vs. Ceramic Englne 

Cumulative 

GW Installed 

8 

24 

40 

Strategic Elements SavingslEngine: Cr, Co, W, Mo, Cb, Ni 

Component Total Unflnlshed Wei~ht (Ibs.1 

Combustor 447 

Turbine 1408 

Turbine Diffuser Houslng 839 

Total 2694 

Materials Response Group, Virginia Polytechnic Institute & State University 

Engines Required to Satisfy Need 

MetJiic 

814 

2443 

4071 

Ic 

571 

1714 

2856 
I I I Ceramic Matrix Composites 

-> Application example - valve guides 
Ceramic Matrix Composites 

/II'I'LlCATION AREA: I'ItIMAItY AND SECONDAItY RlEI'ALS I'ItOCESSINC 

I'I~OSI'ECTI YE CIiCC COI1II'ONENTS: It ADIAN'I' OH IMMERSION IIEA'I'ER 'I'UIIES 

I 

~TEXTRON I 

Specialty Materials 

-> Application example - immersion heater tubes 

P ROSPEC'L'IVE CFCC COMI'ON EN'I' AI'l'LICA'I'IONS 

OXIDIZING, RIOL'I'EN RIE'I'AL Olt INIZII'I' 

2300-2600°17 (IZ00-14U0°C) OI'EItA'I'lNC 'I'Ehll'S 

l'HINCII'AI,LY I'lIERMOMECIIANICAL (AND LR.1I'AC'I') LOADING'; (I'EItIIAI'S 

15-20 ksi (100-130 RlPa) STRESS LEVELS) 

ONE TO FOUlt YEAR LIliE'J'IME 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I I Ceramic Matrix Composites 

SURFACE COMBUSTION'S 

BIQ FURNACE 

I 

I b!h 

Materials Response Group, Virginia Polytechnic Institute & State University 

-> Application example - soaking furnaces 

'Il+lC++ 

+I++++ ARCA.-. amercorn H..r,.L I".(*- + +I 
I I 1 Ceramic Matrix Composites 

I AIJPLICATION AREA: PE'I'ROCILEMICAL PROCESSING INDUSI'RY 

IJIIOSI'EC1'IVE C1;CC COAflJONENT: CA'I'ALY'I'IC IIEIiORMElI 011 IBYItOLYSIS 'I'UUIIS 

/ 

Proccrr Far Out 

-+ 

Coolcd 

Combusttun 

Car Out 

- Application example - chemical processing 

I'ROSPECTIVE CFCC COMIDONENT AYPLICA'I'IONS 

0XII)IZING; MO1)EIlKI'E-IIIGII PAITI'IAL I'IIESSUIIES 01; S'I'EAM 

2300-2600°C)OYE11A'I'ING 'I'EMI'S 

I'RINCIPALLY 'I'IIEIIMOMECJIANICAL (AND IMPACT) LOADING; (L'EIIIIAI'S 15-20 

ksi (100-130 MPa) S'I'IIESS LEVELS) 

LIFE'I'IME UP '1'0 'I'EN OH MOItE YEAllS 

ITEXTEN 1 

Specialty Materials 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I I Ceramic Matrix Composites 

111111 

111111 ARC atnetcorn ..-. Y.",*. Urn rn! 

I 

RADIANT BURNER TUBES 

(SURFACE COMBUSTION) 

CONTINUED 

-> Application example - radiant burner tubes 

BENEFITS - ASSUME FULL MARKET POTENTIAL 

ANNUAL ENERGY SAVINGS 

BATCH INTEGRAL QUENCH FURNACES 

3000 FURNACES 

8000 HOURSNEAR 

CURRENT TEMPERATURE 

INCREASED RECUPERATION => 280 MW-Hrs 

(500 BBLS OF OIL) 

ELECTRIC PIT FURNACES 

900 FURNACES 

8000 HOURSNEAR 

CURRENT TEMPERATURES 

CONVERSION FROM ELECTRIC TO GAS FIRED => 790 MW - Hrs 

(1,400 BBLS OF OIL) 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I I Ceramic Matrix Composites 

-> Production methods and costs 

I 

-> Reliability, reproducability, inspection methods 

-> Availability of design data (static, long term) 

-> Thermal stability 

Technical Constraints - 

-r Supporting technologies - 

* Characterization methodologies 

* Durability, damage tolerance, life prediction 

* Design methodologies 

Materials Response Group, Virginia Polytechnic Institute & State University 
. ii: I Ceramic Matrix Composites i i i 

; i i i I Preliminary Design Properties - 

-s Stiffness and strength (all anisotropic values) 

-r Coefficients of thermal expansion 

-> Thermal conductivity 

-> Thermal diffusivity 

-> Creep, creep-rupture, fatigue behavior 

-> Environmental degradation 

Materials Response Group, Virginia Polytechnic institute & State University 
ba

4_

iC ° °

-> Each composite system offers a range

of properties and performance

L_ D T 300/5208

200 0 GY70/5208

• 7075-T6

• • 4130

SCS-2-AI

• Borsic/Ti

0 I I I I

0 I0 20 30 40

Modulusof Eloslicily

Materials Response Group, Virginia Polytechnic Institute & State University
Ceramic Matrix Composites 

-> Reinforcement is the key to properties 

and performance 

. - 

(b) 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

A weave pattern 

I 

\crimping near a crossover 

-> Local fiber architecture influences performance 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

ternal constraints 

A+ 

cause thermal stresses 

C (F) + 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I I Ceramic Matrix Composites 

-> Damage tolerance (fatigue) 

I 

-> Resistance to creep, creep rupture 

Durability- 

-> Resistance to aging 

- chemical 

- physical 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

1 1 - Matrix cracking is a dominant damage mode 

Fibers control the effect of 

matrix cracking 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I 

Materials Response Group, Virginia Polytechnic Institute & State University 

Ceramic trix Composites 

/ = Local damage modes control damage tolerance 
Ceramic Matrix Composites 

" f 12345678 

Materials Response Group, Virginia Polytechnic Institute & State University 

I 

-> Fibers can break many times before '!rupturew 
Ceramic Matrix Composites 

-> Damage tolerance (fatigue) 

* Failure modes are similar 

to those for short-term behavior 

* Internal stress redistribution 

results from damage modes 

* Composite systems fail from the 

(statistical) accululation of defects 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

= Damage develops by accumulation 

I I 

I 

RESIDUAL STRENGTH I 

I 

.RUPTURE 

POINT 

I I I 

I a n STAGES I 

I I I 

I I I 

log N 

Materials Response Group, Virginia Polytechnic Institute & State University 
-> Resistance to (physical, chemical) aging 

Modulus 

Temperature 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I I Ceramic Matrix Composites 

* Chemical reaction rates or 

diffusion may control rate 

I 

or chemical aging 

-> Resistance to (physical, chemical) aging 

Temperature 

Materials Response Group, Virginia Polytechnic Institute & State University 
I 

I -> Resistance to creep, creep rupture 

I I 

Slope = ? 

Ceramic Matrix Composites 

Stress 

Materials Response Group, ~irginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

* Combined effects may be "anomalous" 

I 

* Mechanisms control the 

slope of the rate curve 

-> Resistance to creep, creep rupture 

* Temperature greatly affects 

the controlling mechanism 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

-> Damage tolerance (fatigue) 

ining Strength 

Stress 

..--*-- 

.------------------ 

Cycles 

Materials Response Group, Virginia Polytechnic Institute & State University 
Durability - The Problem: 

I I Ceramic Matrix Composites 

Initial 

strength 

' 

Degradation 

How can we combine our data and understandings of material system 

Cycle 

dependent 

f damage 

behavior under long-term conditions to estimate remaining strength 

and life, or to make a better material system? 

if Kinetic 

Processes 

Geometry 

4 

\ 

Constitutive 

Chemical 

Thermodynamic N 

life 

Materials Response Group, Virginia Polytechnic Institute & State University 
III Ceramic Matrix Composites 

Our Approach: 

laminate 

/ 

"damage" 

"Critical Element Concept" 

- identify a local material element whose failure defines 

global failure for a given failure mode. 

4 

subcritical 

I critical 

element(s) 

failure modes 

element A A 

representative volume 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic 2Matrix Composites 

Degradation Processes Modeled: 

St iff ness Strength 

Phenomena Change Change 

Stress relaxation X 

Oxidation 

Viscoelast ic creep 

Creep rupture 

Moisture effect 

Aging 

Environmental degradation 

Temperature effect 

MRLife TM 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I I Ceramic 2Matrix Composites 

- 

Remaining Strength 

1 I Failure Criterion I 

I I 

State of . State of 

Stress Material 

I I 

Micro-, Meso-, - Properties, 

Macro-mechanics Evolution 

I 

Subcritical Critical 

N2 

Elements Element 

life N1 

Damage Failure 

Modes Mode 

I 

I Loading History, geometry, Properties 1 

MRLife TM 

Materials Response Group, Virginia Polytechnic Institute & State University 
I I 

Residual / / 

strength Failure criterion Current life 

1. K/Kc 1. Constituent SN 

Fora given 2. Tsai-Hill 2. Kinetic process life 

failure mode 3. A€ / M(critica1) 

Ceramic Matrix Composites 

1 

1 4. (Others ...I 

Residual Strength Calculation: 

MRLife TM 

Materials Response Group, Virginia Polytechnic Institute & State University 
Ceramic Matrix Composites 

1 Rate Equations Needed: 

>> Chemical - activation rates 

>> Cracking - density vs. applied conditions 

>> Creep - compliance vs. time (tensor components?) 

>> Delamination - rate as a function of energy release 

>> Geometry or property degradation rates 

MRLife TM 

Materials Response Group, Virginia Polytechnic Institute & State University 
III Ceramic Matrix Composites 

MRLife 

A Performance Simulation Code 

for Material Systems 

An Opportunity: 

The MRLife code, and the critical element philosophy behind it, present 

a unique opportunity to design for durability, damage tolerance, 

reliability, and safety in a rigorous, economical, convenient, and 

competitive manner. 

Materials Response Group, Virginia Polytechnic Institute & State University 
Implementation: 

I I 

Integration into Design Codes - MRLife TM 

>> Full Integration: _ - - ---->------- - - _ # - - - # 

- - . 0 r-z-:, ..: . . . 0 

0 ".J . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . ...... . 

. . . . 

. 

. . . ;' MRLife . \ 

\ 

\ 

\ 

Simulation Structural \ 

\ 

\ 

Reliability I I 

Analysis 

Structural Analysis 

Ceramic Matrix Composites 

. 

\ 

. . . . - . (Stresses) - 0 @ . , Remaining Strength - - - # - - - - _--- ---______--- 

Life 

Cycles / Time 

Materials Response Group, Virginia Polytechnic Institute & State University 
Designing with 

Continuous Fiber 

Ceramic Composites 

Summary: (CFCCs) 

CFCCs have unique high temperature and 

aggressive environment capabilities 

We can design safe, reliable structures with CFCCs 

More experimental characterization and design 

experience will make the design effort 

quicker and easier 

Ken Reifsnider 

Materials Response Group, Virginia Polytechnic Institute & State University 
111 Ceramic Matrix Composites 

-> Joining, load application methods 

-> Process control methods, methodologies 

I 

-> Processing 1 property relationships 

-> Basic understanding of behavior 

other issues - 

Materials Response Group, Virginia Polytechnic Institute & State University 
NANOSTRUCTURED MATERIALS

Robert D. Shull

United States Department of Commerce

National Institute of Standards and Testing

B-140, Materials

Gaithersburg, Maryland 20899

Telephone

289
290
NANOSTRUCTURED

MATERIALS

_ob_rt_. _hull

(Magnetic Materials Group)

Metallurgy Division

National Institute

of Standards and Technology

Gaithersburg, Maryland

USA

291
STRUCTURE SCHEMATIC:

-NANOPHASE MATERIALSchematic of an equiaxed nanocrystalline metal showing atoms

associated with individual grains (filled circles) and those

constituting the grain boundaries (open circles). [H. Gleiter,

Prog. Mater. Sci. 89, 223 (1989)]

292
2rim

High resolution TEM picture of Nanophase Pd.

[G.J. Thomas, R.W. Siegel, and J.A. Eastman, Scri. Metall. 24, 201

(1990)]

293
HIGH INTERFACE VOLUME

-NANOPHASE MATERIALSPercentage of atoms in grain boundaries of a nanophase material as a

function of grain diameter, with grain boundary thickness of 0.5 and 1.0

nm (i.e., 2 or 4 atomic planes). [R.W. Siegel, Annu. Rev. Mater. Sci.

21,559 (1991)]

294
ATOM LOCATIONS

-NANOPHASE MATERIALS1

- REGION

Z

o_

t---

(D

rr"

t.l.. j_

toO. 1

-- • ,%

0.01 1 , ,

1 10 100

GRAIN SIZE, nm

The effect of grain size on the calculated volume fractions for intercrystalline

regions, grain boundaries, and triple junctions, assuming a grain boundary

thickness of 1 nm. [C. Suryanarayana and F.H. Froes, Met. Trans. A23,

1071 (1992)]

295
VAPOR-CONDENSATION

PROCESS

f LIQUID NITROGEN

Schematic of a gas-condensation chamber for the synthesis of

nanocrystalline materials. [R.W. Siegel, MRS Bulletin 1___55,

60 (1990)]

296
VAPOR-CONDENSED

PARTICLE SIZE DISTRIBUTION

I ILl I I !

200 _

150 --

z

I00 _

50 _ m

r

o FF I I I

0 5 IO 15 20 25 30

GRAIN DIAMETER (nm)

Grain size distribution for nanophase Ti02 (futile) sample

compacted to 1.4 GPa at room temperature as determined via

TEM. [R.W. Siegel, S. Ramasamy, H. Hahn, Z. Li, T. Lu,

R. Gronsky, J. Mater. Res. 3, 1376 (1988)]

297
CHEMICAL ROUTES TO

NANOPHASE AND NANOCOMPOSITE

MATERIALS AT NIST

1. "Modern" Chemical Procedures

(a) Sol-gel fechniques

(b) Confrolled Pyrolysis of

mefal-organo complexes

(c) Reducfive dehalogenafion

2. "Classical" Chemical Procedures

(a) Coprecipifafion

(b) Ion reduction in solution

(c) Use of oxidizing, reducing,

nifriding, dehalogenafing, etc.,

gases

298
METAL ION - ORGANIC COMPLEX ROUTE 

Soluble Metal ionOrganic Molecule 

Complexes 

Polymer Multicomponent 

Oxide Powder 
INCREASED YIELD POINT

_ 200 ............................................................ "/- _-........ ......... Y-_....... ......'-i!"_-;ain size

-_ 100 ..................................... / i

o V,,?,,_ .,, _, ,, i,,,,

0.0 0.5 - 1.0 1.5 2.0 2.5

Strain (%)

Stress-strain curves for nanocrystalline (14 nm) and coarsegrained (50 /xm) Pd, measured at a strain rate of 2x10-5 s-1.

[G.W. Nieman, J.R. Weertman, & R.W. Siegel, Scripta Metall.

Mater. 24, 145 (1990)]

300
LOW TEMPERATURE

SINTERABILITY

Vickers microhardness of TiO2 (rutile) measured at 300 K as

a function of one-half hour sintering at the indicated

temperatures. Note that the 12 nm grain size rutile sinters at

temperatures 400-600°C lower than coarse-grained (1.3 Fm)

material. [R.W. Siegel, S. Ramasamy, H. Hahn, Z. Li, T.

Lu, & R. Gronsky, J. Mater. Res. 3, 1376 (1988)]

301
GRAIN SIZE STABILITY

. 1 I , _ z ! , , , _ !

0 500 1000

Sintering temperature in °C

Density (open symbols) and grain size (filled symbols) of

nanocrystalline TiO2compacted at the indicated pressures as

a function of sintering temperature. [R.S. Averback, H.

Hahn, H.J. H6fler, J.L. Logas, & T.C. Chen, Mater. Res.

Soc. Symp. Proc. 158, 3 (1989)]

302
OPTICAL TRANSPARENCY

nanoph , 0 R .

Disks of nanocrystalline Y203 showing that the optical

transparency can be controlled by changing the pore size. (J.C.

Parker, private comm. 1/94)

303
INCREASED CHEMICAL

ACTIVITY

Activity

0.5 I I I I I I

Activity of nanocrystalline TiO2 for H2S

decomposition as a function of exposure time at

500°C compared with that from several commercial

TiO2 materials and a reference (A: 76 m2/g

nanocrystalline rutile; B: 61 m2/g anatase; C: 2.4 m2/g

rutile; D: 30 m2/g anatase; E: 20 m2/g rutile; and F:

reference alumina). [D.D. Beck and R.W. Siegel, J.

Mater. Res. 7_,2840 (1992)]

304
INCREASED ABRASIVE

WEAR RESISTANCE

800

Nano

Nano O M A,, 6Co 0.3

,,,ano,.qne 13Co 0.3 gm

v CompanyA Nano

_. 70O 15Co 0.4 o

• Nano

CompanyB O 15Co 0.3 pm

Z 600

v

(1)

o

c

-,-, 500 6Co 1pm

03 °_

03

d_ 6Co 0.8 pm

r'r" .

t-- O 400 15Co 1-2 gm

°_

03

"-Q 20Co 1-2

< .

300 6Co 1-2 l.tm

10Co 4 gm

200 i I I I I I I I I I I

1000 1200 1400 1600 1800 2000 2200 2400

Hardness (kg/mm2)

Abrasion resistance vs. hardness for conventional and

nanocrystalline WC-Co materials. [L.E. McCandlish, private

comm. 1994]

305
INCREASED ELECTRICAL

RESISTIVITY

100 - o 30 nm

O

O

O

O

O

80 -

O

O

O

O

,_ o o [] 40nm

r--

60 - D DD [] 0

-._ [] O []

_L [] [] • • 50 nm

DO • • °° ° °

40 _ oO • •

[] [] [] nu 90 nm

[] []

II []

[] []

Nil

20 -

I t I

50 1O0 150 200 250

T (K)

Variation of electrical resistivity with temperature for

nanocrystalline Fe-Cu-Si-B alloys. [Y.Z. Wang, G.W.

Qiao, X.D. Liu, B.Z. Ding, & Z.Q. Hu, Mater. Lett. 17,

152 (1993)]

306
REDUCED MAGNETIC

COERCIVITY

100

10 -

O 1 _ D6 . Fe-Si

"r"

L

__

_ 0.1 -

13:: o

IL!

0

0

0.01 - amor- 1"

phous / perm- [] \

x- - '_ alloy []

0.001 I I I

1 nm 1 p.m 1 mm

GRAIN SIZE, d

Magnetic coercivity vs. grain size for several soft ferromagnetic

materials. [G. Herzer, IEEE Trans. MAG26, 1397 (1990)]

307
NANOCOMPOSITES

Spherical particle Disk-type particle Rod-shaped particle

O Materials possessing acharacteristic

size scale on the order of = 1-20nm

O For magnetic properties: critical lengths

are grain size, magnetic species

diameter (+ separation), and magnetic

exchange length

O Are Composites of two or more magnetic

states; highly composition dependent

O May be single or multiple phase

Can be prepared from the vapor, from

chemical solution, via precipitation,

and by deformation

@ Possess (1) UNIQUE properties, (2) NEW

magnetic states, and (3) UNUSUAL

property combinations

Provide Opportunity for Electronicand

Magnetic Engineering

i;- _'.i °°_\! :,,

Fiber Thin layer Lamella

308
Zero Thermol Coefficient of Resistc]nce

METAL NON-METAL

Temperature (T) Temperature (T)

NANOCOMPOSITE

(Au +Ta205)

ID

0

C

- o_

n,-

Temperature (T)

Resistors requiring NO WARMUPPERIOD

3g9
NANOCOMPOSITE

(Ml-xNx)

PARAMAGNETIC

TC

SUPERPARAMAGNETIC

FERROMAGNETIC

Magnetic 0.3 0.5 0.7 Non-Magnetic

Species Vol. Fracf. N Species

(M) (X) (N)

310
Conventional Magnetic Recording Media

Fe30 4

O0 000

0000 0 0

0

0

High Density Magnetic Recording MediG

NANOCOMPOSITES

oo ooo __

OOoo o o

° ooooo °ooo o° -I 20 (2Angstroms nm)

Fe504- Ag

311
SOFT

MAGNETIC MATERIALS

For Large Grains:

Magnetization (M) is determined

largely by magnefocrystalline

anisofropy (K)

For Small Diameters:

Increased importance of ferromagnetic exchange

causes decrease in K

Nanocrysfalline Fe-Cu-Nb-Si-B

("Finemet")

Average Anisotropy <K> in kJim 3 loo

10, E 7-'*

o 10- ;" _".

, . I/0

< ._ ".

.I g • O

8, c 1 '* 6. U

6 "1- 0 6', °'. o

o.t ; a..

O< , O>Lex "_ ; %. o

4 "0 + • A

_,0.01- g %, "

o _..... .' ,, "" (O

2 0.001 ......

Into I/z_ Irne

O0 10 2o 30 4"0 50 Grain Size D

GrainSizeD innm E (*) amorphouCso(Fe)-base

Fig. 7. Theoretical estimate of the average anisotropy (K) : noFe-nS_ocGtysta .5 wtllXinFee-Cu._,Nb,(SiO).._

for randomly oriented u-Fe-20at.%Si as a function of grain o 50 _-ge

sizeD. AP_.oy

G. Herzer, Mot'Is. Sci. & Eng. A133 (199 1) p, 1.

312
REDUCED CORE LOSSES

Comparison of core losses of conventional coarse-grained Fe-3.5 wt. % Si,

amorphous Fe-9 at. % Si-13 at. %B, and nanocrystalline Fe-7 at. %Zr-1 at. %Cu6 at. %B alloys as a function of maximum induction field (Bin) and frequency

(f). [A. Makino, K. Suzuki, A. Inoue, & T. Masumoto, Mater. Trans. JIM

32, 551 (1991)]

313
HARD

MAGNETIC MATERIALS

"Magnequench" Magnets

/,0 \_ Ixld15Fe77B_

""-. .... _) lqdpl-e 14B

\ II 1,1_I 1. I I:e 4 l:_-I

\ --

I I 1 I l --I' I I

Fe 20 /,0 fi() 1 8() Nd

/

Nd 7 ITC .3

Figure 7. A compadsan ol Ihe phase relations in the equilibrium phase diagram (solid line) and

in lhe melaslable phase diagram (dashed line).

E

2

Nd

Figure 8.The idealmicrostructureof asinteredmagnet. 1he hard magneticgrains (@are ) decoupled

by neodymium-rich nonmagnetic grain boundary phnse.

A. Hutfen, JOM (March, 1992) p. 11.

314
GIANT MAGNETORESISTANCE

Fe-Cr-Fe Multilayers

/7_U=o

4.2 K _o3o_fsA, )_o

(VoSO_ 9 A),_

os T

u,

! | ! l

-40 -30 -20 -I0 0 10 20 30 40

Magnetic field (kG)

Baibich, et. al., Phys. Rev. Left. 61 (1988) p. 2472.

Co-Ag Nanocomposites

C%AgTs (T^=600°C ) at 5 K

4.0 9

.-. 3/; _ 7

3.2 S

K

_s P(IIs) 3 I-_

I l I f

-so -_o -_o Io _o so o o.I o_ o_ o.4 o_ oG

II (l_Oc) 1 / r ( nln "_)

Xioo, et. o1., MRS Symp. Proc. 286 (1993) p. 197.

315
NEW

MAGNETIC

REFRIGERANTS

1.0

• t

• j

- : spin 7/2 atoms 0.8 "

,

i 10 atom clusters

; i

" ' 30 atom clusters

_ ().6 : '

;

°o

- ',

I 1O0atom clusters

I

°° o I

• I

°Ool

_,._0.4 _,..

°l °

" i'"....

• QOOO_oo

% •

0.2 "...

_.'.------.-2_"":.........

I I i I I ! i I i

0 20 40 60 80 100

Temp (K)

Calculated entropy change vs T for a magnetic field change of

1 tesla for a system of magnetic spins isolated and grouped into

clusters as in magnetic nanocomposites. Note the enhancement

when clustered. [R.D. McMichael, R.D. Shull, L.J.

Swartzendruber, L.H. Bennett, & R.E. Watson, J. Mag. &

Magn. Mater. 111, 29 (1992)]

316
[MAGNETOCALOR IC EFFECT ]

High Spin Entropy LowSpinEntropy

_*", J _ -'_'_"- Adiabaticapplication I I I * { *

°f a magnetic field (H) I I { { I I

i -_ "_ _","" lowersthe magnetic

_%.M" ¢ _ ¢ _ spin entropyand { { i i I i heats the sample.

d" \ _ _ _-'-_ Removal ofthefield I i I I i I H coolsthe sample.

Zero Field Applied Field

MAGNETIC

REFRIGERATOR

Cyclicmotion of a _Cyclicmotion of. refrigerant in and out of refrigerantin ana

a magnetic field while } out ot the field

alternating the thermal Heat Exchan connections between two

Tube filled with

heat reservoirs allows the (Heat) heat exchange transfer of heat from one fluid

reservoir to the other: i.e.,

a refrigerator. _Magnetic Shutter Nanocomposite

Refrigerant \ .....

GeneralMotorsCorp. ., -_-i

isworkingwithNIST (, "-,

to developnewmaterials _ .', Windings Mag_ et

for higher temperature (.., "-,

coolingjobs,such as Heat

ear air conditioners.

317
SINGLE-PHASE

MAGNETIC NANOCOMPOSITE

REFRIGERANT

Schematic of the Gd3Gas_xFexO12magnetic nanocomposite

structure showing atomic positions, spin directions (via

arrows) of the Gd atoms and the locations of magnetic

clusters (dashed lines). [R.D. Shull, R.D. McMichael, J.J.

Ritter, and L.H. Bennett, MRS Symp. Proc. 286, 449

(1993)]

318
MEASURED

MAGNETOCALORIC EFFECT

FOR Gd3Gas_xFe_O12NANOCOMPOSITES

2.0 0 x=2.5

0.0

0 20 dO 60 80 100

Temperat ure (K)

Measured entropy changes (for a field change of 1 tesla) vs T for

paramagnetic GGG (x=0) and magnetic nanocomposiies GGIG (x > 0)

showing enhanced magnetocaloric effects of tile nanocomposites.

[R.D. Shull, R.D. McMichael, J.J. Ritter, and L.H. Bennett, MRS

Symp. Proc. 286, 449 (1993)]

319

DEVELOPMENT OF COURSE MODULES

FOR MATERIALS EXPERIMENTS

Kristen P. Constant

and

Krishna Vedula

Materials Science and Engineering

Iowa State University

3053 Gilman Hall

Ames, Iowa 50011

Telephone 515-294-3337

321
322
DEVELOPMENT OF COURSE MODULES FOR

MATERIALS EXPERIMENTS

K.P. Constant and K. Vedula

Materials Science and Engineering

Iowa State University

3053 Gilman Hall, Ames, IA 50011

Key Words: Computer Courseware

Prerequisite Knowledge'. Basic math, chemistry and physics for entry-level materials science

laboratories, elementary computer skills.

Objective: To enhance Iearning in materials sciencelaboratories.

Equipment: This coursewareis presently Macintosh compatible, although a PC version will be

available in the near future. The minimum system configuration issystem 7.0 or higher, 4 MB

of RAM, and prefers 256 colors.

Introduction:

Recent U.S. government-sponsored studies of the decline of international competitiveness have

reported that one of the most severe problems is the lack of education of future engineers in

synthesis and processing of advanced engineered materials. In response, the National Science

Foundation has made awards 6 universities to develop materials processing coursematerials

for improving processing education. Iowa State University is among those selected.

Approach:

Development philosophy

A common problem with introducing new course material to an existing curriculum is that

most programs are considered to be "over-committed" in terms of course topics and time and

have very little flexibility. Few departments can afford the curriculum space to introduce an

entirely new course in their program, and therefore must depend on introducing new or

expanded material in the framework of the already existing courses. Since there is an

outstanding variety of programs which include materials science and processing, flexibility is

the key. In order to ensure that the materials developed at ISU can benefit the maximum

number of students in Materials Science and Engineering, a new approach was developed.

A system involving flexible teaching modules has been designed to respond to the varying

needs of existing departments, including that at Iowa State University. Each module is a 4-6

week set of teaching lectures and laboratories which can be used individually or together. This

approach addresses the needs not only of the education of students majoring in the field of

323
materials science and engineering, but also in allied disciplines either in the form of service

courses taught to non-majors, or materials-related courses taught by other departments.

Computer-based course development was selected as a mode of delivery largely because of its

flexibility. Computer based course material (courseware) can be designed such that the

modules emphasizing specific processing techniques share common links to fundamental

concepts so that each module can be as complete and concise as possible without repeating

common material. Courseware also allows great flexibility in the order of presentation of

materials, a significant departure from the traditional linear textbook approach. Also, the user

can choose the level of the presentation, from basic to advanced. Delivery of courseware over a

national network also provides maximum availability to students and educators. Additionally,

courseware provides functionality not easily achieved in "hard copy" form. Specifically, color

photographs and images, animations, videos, and sounds'are easily accommodated. Finally,

courseware can be designed to require interactive learning -- the student is asked to answer

questions or provide some sort of input in order to proceed. It has been suggested that active

learning is more effective for a majority of students than classical passive learning styles

frequently associated with lectures or reading a text. Since this interactive component is

particularly well-suited to laboratory exercises, the scope of lab exercises has been expanded to

include 9 experiments outsidethe area of materials processing for use in an introductory

materials science class.

Software description

Authorware ProfessionaV M2.0.0 courseware development software was selected as a vehicle

for delivery of these modules for a number of reasons. This software is available for both the

Apple Macintosh and IBM-PC compatible platforms, and can be translated from the Macintosh

to the PC, utilizing a large fraction of educational computing equipment already in place. This

software also allows the "packaging" of programs so that the end product is self-contained.

The user does not need to own the softwarein order to use the product. This software also has

a full range of multi-media capabilities.

Navigating through the courseware is through pull-down menus and click-touch areas similar

to those familiar to most students who have worked either in the Macintosh or Windowsenvironments. Within each section, push-button forward and backward arrows allow the

students review material already presented. There is an optional "help session" available either

at the beginning of a session, or at any time during the session which fully describes the use of

the program. In the processing courseware, there are module-specific problems and

experiments. The laboratory exercises make use of a variety of interactions including

"assembly" interactions where a student is asked to drag and drop items with the mouse

(either labels or pictures) to an appropriate place on the screen (sometimes in a specific order).

This is extremely useful for "walking through" a lab experiment and equipment use before

going in to lab. The experiments have an introduction, a background, a procedure and an

analysis section, as well as information on safety and handling of the equipment and materials

used.

The effectiveness of this approach is being tested this semester in an introductory materials

science laboratory at Iowa State University. Students are required to complete a tutorial on the

324
computer before attending the laboratory. One:of the major advantages over other types of

pre-lab exercises (in written form, or on video tape) is the ability of the computer to provide

feedback both to thestudent and to the professor. Built into the software is a record tracking

scheme so that a professor can access a file that records which students have accessed the file

and what responses were given for various interactions. This provides a unique opportunity

for the instructors to learn which parts of the laboratory are most confusing to students so they

can provide additional information before and during the laboratory

Sample experiment:

Twelve experiments have been developed covering various concepts in structure of materails,

phase equilibria, defects and electrical, thermal, and mechanical properties. One such

experiment introduces phase diagrams through the use of the Pb/Sn system. The experiment

involves identifying the composition of a Pb/Sn alloy by measuring the cooling curve and

consulting the phase diagram. A number of concepts are employed, including binary phase

diagrams, the lever rule and the phase rule. In the computer lab-tutorial the student completes

exercises which describe phase diagrams including the level rule, the amountof phases and

their compositions, and the phase rule. These exercises involve the student by requiring

moving labels to appropriate areas, or by pointing to correct answers or by typing responses

The student is then quizzed on various aspects of binary phase diagrams. Figure I shown one

screen which requires the student label various parts of the phase diagram as they flash on the

screen.

Binary Phase Diagram

In this lab, each groupwill receivea Pb/Sn sample&unknown

composition. The composition&this samplecanbe determinedwith the

use of thePb/Sn phasediagramandthe coolingcurve from solidification

&your sample. Fromthe liquidusandsolidustemperaturesandthe

amountof each constituentpresent, the compositioncanbe derived.

Move theword liquidusto the pointon the diagramwhere the

compositionX crosses the liquidus.

L liquidus

100% A X lO0%B

composition (%B)

Figure I A screen which shows the drag and drop interaction.

Students are asked to name various parts of the phase diagram.

325
After the introduction, the experimental procedure is reviewed. In this section, students are

required to assemble the apparatus for measuring the temperature of the alloy on cooling.

Students may choose to review the use of the microprocessor based controllers used in this

laboratory, if necessary. (Figure 2). Finally, typical results are shown and the analysis is

discussed. (Figure 3)

Set Paint I --

1800 factual temperalvre)

_C 1800 _ Set Variable

iiflplJt tefnperature)

index Button Enter

[next menu llem) (stores changes)

Up Arrow € Down Rrraw

(increments value ur Oli) {decren|entsvalue or off)

The microprocessor controllers

have been programmed for type

K thermocouples; these

controllers should display the

temperature in °C.

Figure 2 A screen from the tutorial on using furnace controllers.

Results

Plotssimilamr thoseoutlinedbelowcan be constructefromd the

solidification data (assuming that T_ is room temperature,- 26°C,

and Tois3600C).Notethatthearrowsindicatea changeinslope.

The pointsforthechange inslopeon theTemperaturevs.time

plotbecomemore evidentwhen linesaredrawn.

o) Temperature vs. time b) Jog T-Too vs. time

To-Too

8.5

Temp (°C) log T-T____

To-Too

Tliquidus'

I's_lidu,

125 i,85

$ time (see) 58_ 8 time (sec) 5OOil

Figure 3 The Results screen shows the student typical results

326
Constraints and Challenges:

Dual Modes of Use

These experiment modulesnecessarily rely on the availability of specific equipment. Although

we have made an attempt to include general equipment which is probably available in most

materials science departments, it is quite likely that some of the experiments cannot be

performed in some departments. We include sample results and reports for experiments which

will provide some learning experience (though not hands on), for students in equipmentlimited situations. In the case where equipment is available, the professor may choose to limit

the students' access to the results and interpretation section to allow the student to perform

these tasks alone.

Module Size

Multimedia computing can providea rich experience of sight and sound, but can also require

sophisticated hardware and large quantities of computer memory. We are attempting to limit

file size and use file-compression schemes which would allow even modestly configured

computers to use most, if not all of the capabilities of the modules.

Copyright issues

Although these modules will not be sold, there are copyright issues which must be considered

especially for use of graphics. Since the laws relating electronic duplication and manipulation

of images are not well defined, we have been keeping careful records of the sources of graphics

used in these modules. We will seek guidance on these legal aspects, and seek permission

when necessary.

Assessment of Effectiveness

Although it is difficult to assessthe effectiveness of these lab modulesin enhancing the

laboratory learning experience, we hope to learn from student responses to questionnaires. We

also plan to test this material at other universities and solicit suggestions for improvement.

Future Work:

Work on experimental moduleswilI continue both improving existing modulesand expanding

the scope of experiments to include a broader range of advanced materials. A module

involving laboratory safety is also planned.

This work is funded by theNational Science Foundation and the Engineering Computing

Support Services.at Iowa.State.University

327

TESTING SAND QUALITY IN THE FOUNDRY

(A BASIC UNIVERSITY-INDUSTRY PARTNERSHIP)

Donald H. Martin

School of Manufacturing Technology

Tri-State University

300 South Darling Street

Angola, Indiana 46703-0307

Telephone 219-665-4265

and

Hermann Schwan

Production Manager

Auburn Foundry Group Europe

Gebruder Gienanth

Eisenberg, Germany

and

Michael Diehm

Product Development Engineer

Auburn Foundry, Inc.

Auburn, Indiana

329
33O
TESTING SAND QUALITY IN THE FOUNDRY

(A BASIC UNIVERSITY - INDUSTRY PARTNERSHIP)

Donald H. Martin

Associate Professorof Manufacturing

Tri-StateUniversity

Angola,Indiana

and

HermannSchwan

ProductionManager

AuburnFoundryGroup Europe

Gebmder Gienanth

Eisenberg,Germany

and

Michael Diehm

ProductDevelopmentEngineer

Auburn Foundry,Inc.

Auburn,Indiana

Key Words: Sand, clay, bonding material, moisture content, grain size, permeability

moldhardness, green compression, friability, sand temperature, compactibility.

Prerequisite Knowledge: No prerequisite knowledge required for this experiment.

Objective: To observe and understand the key elements in sand testing (specifically testing

for moisture content) in a modern flaskless foundry operation. A look at sand, clay, and sand

additive receiving control to reclaiming and controlling process sand.

Equipment: Equipment essential for making moisture tests with the No. 276 Moisture Teller

is as follows:

1. The Moisture Teller

2. Lecture Type Balance, No. 250 or No. 240-A Speed Balance

3. Sample pans with wire cloth bottoms. (Two tared pans of matched weight are

supplied with the No. 276 Moisture Teller.)

4. Counterweight (equal to the weight of the pans) and a 50 gram weight or a set of

weights No. 260, for special work.

5. Pan Lifter for handling pans while hot and soft brush for cleaning wire cloth pan

bottoms (supplied with all Moisture Tellers).

Equipment can be purchased from:

George Fischer Foundry Systems, Inc.

407 Hadley Street

P.O. Box 40

Holly, Michigan 48442

331
Introduction:

One of the most important elements in proper foundry sand conditioning is percentage of

moisture content. Too much moisture and I've got "mud" and gas holes in the cast part; too

little moisture and the sand will not hold its shape and crumble and you lose dimensional

control of the part. There are many deposits of various grades of molding sands found

throughout the world. The most common sands are composed of silicas, which do not melt

or fuse together when they contact the molten metal in the casting process.

We talk about "green sand molding", but we should explain that the sand is not green in

color, but green in process. Green sand molds are widely used in today's foundry practices.

They are simply made of the sand, clay, water, and other materials and are used without

further conditioning. Green means that the molded sand mixture is allowed to remain moist

throughout the manufacturing process.

Silica sands are the most common types of sand used in the foundry operation today. Two

general types are used: naturally bonded and synthetic. Both are found to exist naturally.

Naturally bonded sands (bank sands) can contain up to 10-20% clay-based contaminants and

must be selectively used depending on material being cast.

Synthetic sands (lake sands) are made up of basic sand grains. Most foundries processing

metals at high temperatures use synthetic sands; the sand composition can be more closely

regulated. In malleable and grey iron foundry operations a combination of naturally bonded

and synthetic sands are used to provide quality casting.

Due to the shape of the grains and to some extent the amount of washing, wet-reclaimed sand

usually appears grey. This is because of the retained carbon deposited on the sand grains.

The silica sand on the beach or bank sand will not hold its shape unless a bonding agent,

usually clay of some type, is used to hold it together. We then add water (from 3 to 9%)

depending on the material being cast and arrive at the required specifications for sand

conditions required to consistently produce quality casting.

The size of pores (holes) in the face of molds varies depending on the sand size and shape

and are determined by the mixture of various mesh sand sizes.

Clay is the most commonly used bonding material for molding sand. When clay is mixed

with the correct amount (percent) of water, it is made plastic and adhesive and holds the sand

grains together. When water is added to a mixture of sand and clay, all the water is absorbed

by the clay. The shear strength of high-water clays is always low. As the amount of water

decreases, the strength rises, slowly at first, but further decreases in water content cause a

sharp rise in strength up to ideal sand specification (mixture).

Moisture determination of warm or hot sand needs special attention to enable the lab

technician to obtain a moisture percentage that is meaningful. First, it must be realized that

warm or hot sand is tempered with additional moisture to compensate for loss of moisture due

332
to evaporation. The moisture percentage required at the sand mixer increases with an

increase of sand temperature so that when the sand arrives at the molding station, the sand is

not too dry, but contains an actual moisture percentage, which imparts a good moldability.

Therefore, in sand control we are interested in two different moisture tests. One is the

Compensated Moisture Test at the mixer, and the other is the Actual Moisture Test at the

molding station.

In controlling the moisture at the sand mixer, we are interested in the compensated moisture.

The compensated moisture test gives a moisture percentage that anticipates the moisture loss

in transportation and storage. The compensated moisture percentage at the sand mixer is a

constant. Whereas, if an actual moisture test was used showing all the moisture present, one

would have a variable moisture percentage due to temperature fluctuations calling for

different total moisture. Therefore, actual moisture percentage at the sand mixer would

complicate sand control.

Most foundries are now using compensated moisture test readings, but are not fully aware of

the meaning, nor are they conducting the test carefully enough to give them the degree of

moisture control they really need to provide consistent quality cast products.

This also applies to the standard actual moisture test. Its use is primarily for determining the

actual moisture of research batches of sand, or of sand as is delivered to the molders at the

time of molding. The Actual or Standard Moisture Test is, in reality, a check on the

Compensated Moisture Test.

In a continuous foundry operation sand conditions are checked on an hourly basis and

adjustments made to the mixture (either sand, bonding material and/or water are added)

depending on the basic standard test results.

333
ADVANCING TECHNOLOGY TRANSFER 

AUBURN FOUNDRY, INC. 

AUBURN, IN 

AUBURN FOUNDRY GROUP EUROPE 

EISENBERG, GERMANY 

* Disamatic Molding System 

* Sand Testing Laboratory 

* Sand Data Collection Sheet 

* SPC Sand Data Evaluation 

Daily 

Monthly Summary 

* Disamatic Molding System 

* Sand Testing Laboratory 

* Sand Data Collection Sheet 

* SPC Sand Data Evaluation 

Daily 

Monthly Summary 

SAND DATA COLLECTION SHEET

FROM SAND LABORATORY

EISENBERG, GERMANY

m

if)

ta 3_"

in

g Total clay

Gesamtschl,Smmstoff

Clay content %

Schl_mmstol! erb

Loss on ignition %

Gl0hverlust % "nX

o_

g Moisture content %

Feuchtigkeit % _

Gasdurchlgtssigkeit grfin _ Permeability of green sand

I

Druckfestigkeit _ Compressive green strength

gn]n Nlcm2'

" o Friability

Glfihverlust des Sandes

! e-

[ "-1 Shear green strength

Scherfestigkeil N/cm z 1._

Wet tensile strength Nagzugfestigkeit N/cm2

C Staub %

Dust content %

-._=:' Verdichtbarkeit _ Compactability %

.k,_eB_o, . oo_,Oe._,, _ Effective day content %

EinwaaQe/g Total weight

336
Phase I: Testing for Moisture Content:

The MoistureTeller produces a rapidlymoving stream of hot air which is directed at a

weighed sample of the materialto be checked. The hot air dries out the sample in a few

minutes andafter reweighing, only a simple calculationis requiredto determine the percent

loss or percentmoisture in the originalmaterial.

To determinemoisturewith the No. 276 Moisture Teller, there are three steps to be followed:

1. When the No. 250 Laboratory Balance is used, place one of the tared(weighed) pans

on the fight-hand balancepan and the counter-weight on the left, with the slide weight at

zero. Check to see that it balances and, if not, adjust the knurled nuts accordingly. Add the

50 gram weight to the left-handbalance pan, and then quickly place the materialundertest in

the moisturepan until a balance is obtained. (Any undue delay here will cause loss of

moistureduring weighing and will lead to low results.) Distribute materialevenly in the pan.

2. Insertpan into MoistureTeller by depressing rubber buttonon the pan holder and

sliding panin so that it sits evenly in the holder. Release panholder and see that the pan fits

snugly around its top edge against the body of the Moisture Teller. Start the Moisture Teller

by turning the timerpointer to the drying time desired.

3. When the timerturns off the Moisture Teller, remove the pan by means of the lifter

and replace it on the right-hand balancepan. Move the 1 to 10 gram slide weight to the right

until a balance is obtained. The readingof the slide weight scale multipliedby 2 equalsthe

percent moisture. If the samplecontains more than 20 percent moisture,a 10 gram weight

must be placedwith sample panon the right-handpan and added to the slide weight reading.

OR

Determine percentage:

%Moisture = moist weight-driedweight x 100

Moist Weight

NOTE: Clean the sample panafter each use.

The counterweightmay Wearwith continued use and the pans may acquireadhering dirt,so it

is advisable to check the pans againstthe counterweight periodically.

337
Moisture teller.

338
Phase II: Class Tour of local foundry to observe the total foundry process with

emphasis on sand testing and control

Sands for foundry operations are usually a mechanical mixture containing as much as 98%

silica sand, plus clay, carbonaceous material, and water. Fireclay, western and southern

bentonite are used usually in combination to bond the sand grains. The carbonaceous material

may be ground bituminous coal (sea coal), cellulose (cereal and wood flour) or any other

special compounded material either natural or synthetic.

Most companies after years of experience have developed the "correct sand specification" for

their product line.

Automatic molding systems arecommon in most of today's foundry operation. An example

of one such system is the DISAMATIC method (this is a flaskless vertical parted green sand

molding process).

Sand Testing

I Laboratory

339
DISAMATIC Molding Machine (DMM)

MOLDING PRINCIPLE AND MACHINE DESIGN FEATURES

The 2070 DISAMATIC is a shot-squeezemoldingmachine

producingflaskless, verticallyparted sand molds.

The essential componentsfor the productionof the molds

are:

- a molding chamber with fixed bottom, top and side

walls,

- movable pattern plates,

- a sand hopper,

a sand shot arrangement, and

a hydraulic system providing the force for squeezing

and transporting the molds.

The principle of the DISAMATIC molding method.

€€€

•

Filling the molding chamber Squeezing the mold Stripping the pattern and with sand

transporting the molds

340
Define the following terms as they apply to sand testing in

today's foundry operations:

Sand

Clay

Moisture Content

Grain Size

Permeability

Mold Hardness

Green Compression

Friability

Sand Temperature

Compactibility

Naturally Bonded Sands

Synthetic Sands

341
REFERENCES:

1. Dansk IndustriSnydikat,Disa FoundryTechnology,Printedin Denmark,1989.

2. Diehm, Michael, Product Development Engineer, Auburn Foundry, Auburn, Indiana,

August 26, 1994, Plant Tour, Review of Sand Testing Laboratory and Collection of

Sand Test Data.

3. Doyle, Lawrence E., Manufacturing Processes and Materials for Engineers, 3rd

Edition, Prentice-Hall, Inc., 1985.

4. Heine,W. Richard,Principlesof MetalCasting,McGraw-HillBookCompany,1967.

5. Lyman,Taylor (Editor),MetalsHandbookVol. 5, Forgingand Casting,8th Edition,

American Societyfor Metals, 1970.

6. Schwan, Hermann, Production Manager of Foundry Operation Eisenberg, Germany,

August 11, 1994, Plant Tour, Review of Sand Testing Laboratory, and Collection of

Sand Test Data.

342
OBSERVING AND MODELING CREEP BEHAVIOR

IN WOOD

Thomas M. Gorman

Department of Forest Products

University of Idaho

Moscow, Idaho 83844-1132

Telephone 208-885-7402

343
344
Observing and Modeling Creep Behavior in Wood

Thomas M. Gorman

Associate Professor

Department of Forest Products

University of Idaho

Moscow, Idaho

Key Words: creep, creep models,loadduration,woodproperties

Prerequisite Knowledge: Someknowledgeof elasticpropertiesof materialsor beamtheory

is helpful but not necessary. A basic understandingof logarithmsis necessaryto perform the

numericalanalysisand curve fittingexercises.

Objective: To observe the creep phenomenonin a woodbeamplaced underconstantload.

This demonstratesthe need for woodengineersto adjustallowabledesignstressesfor

duration of load. A secondobjectiveis to use experimentaldata to evaluatevarious

numericalmethodsfor creep analysis.

Equipment:

1. clear, straight-grained wood beam (measuring approximately 1/8" x 1-3/4" x 30")

2. weight (approximately 1 Ib)

3. blocks sufficient to support beam ends about 3-4 inches above table

4. stop watch

5. dial gage with support arm

6. log-log graph paper

Introduction:

Creep effects under mechanical stress are observed in most solid materials. For wood-based

structural components, creep and its effect on strength reduction must be accounted for by

considering the "duration of load."

For example, the National Design Specification (NDS) for Wood Construction (NFPA 1991)

provides allowab'e stress adjustment factors for various types of loads -- wind, snow,

seismic, and permanent loads, Depending on whether the expected design loads are in place

for less than or more than 10 years (normal duration), allowable design stresses may be

increased or reduced respectively (Figure 1). In addition, ASTM procedures for testing

wood samples (ASTM 1991) include specific time limits for reaching ultimate stress, as a

way to minimize the effect of loading rate on stress--strain relationships.

This experiment illustrates the need for duration of load adjustment factors by measuring

creep in a simply-supported wood beam and plotting the results on a log-scale. In addition,

mathematical creep models that have been put forth by various researchers are presented,

345
allowing the opportunity for their assessment by fitting the experimental data to the various models.

2.0

1=1 1.9

1.8

1.7

_ 1.6 . •

o o _.5

"_ _ 1.4

I_ h 1.3

r._ _ _.2

_ _ _" 1.0

.,., _ 0.9

_! _ o.8

o_ 0.7

== o.o

0.5

_ 0,4

_ 0,3

_ 0.21

0.0

_-} Z -- I',- _0 _ >

- _.

Duration of Maximum Load

Figure 1. Load duration factors, CD,for various load durations (NFPA 1991).

Procedure:

The phenomenon of creep can be observed by loading a wood beam, such as that described

above in the equipment list, about its weak axis, and measuring deflection over time. As

illustrated below (Figure 2), the beam is supported on blocks, allowing about 1 inch at each

end to rest on the support blocks. The weight is positioned at mid span, and deflectionis

recorded over time with the dial gauge.

Figure 2. Test set-up.

346
The dial gauge can be zeroedas soonas the loadis in place, thusignoring initialdeflection

at time zero. That way, subsequentmeasurementsof defectionwill pertainonly to deflection

due to creep (A_,).The deflectiondata can be recordedon a table similarto Table 1. The

suggested time intervalsare usefulwhen plottingthe resultson a logarithmicscale.

. -": / ?..:% : i :: i(4::

Time (min_) i:: 1/2 1 2 5 10 20 30 45 60

ii.oo.3.oo, .oo .oo7.o,3.o,7 .o,q.o2o

Table 1. Data collection table with experimental data added.

Analysis of Data:

Many empirical creep equationshave been developedby researchers and are availablein

various publications(Bodig andIayne 1982, Conway 1967, Cristwell and Vanderbuilt 1982).

A few of these equationsare included in Table 2.

::i:ii: ::iNam.e ::i:ii ii::iilt:iiii:::_i!_e:!!_i:i: I _!::::. ::ii_:i_!:: :i::::i _i_uai_oni::::::_:z_:!:_ :::i::_::_i [_ii_::!:Co_::ts: z_ii_:_i:i

Parabolic primary a. = atm a,m

Logarithmic primary Acr = a + b log t a,b

Polynomial primary and A. = a + btu* + ct2z*+ dtaz* a,b,c,d,n

secondary

Hyperbolic sine primary and A. = a + b sinh ctm a,b,c,m

secondary (m= 1/3 usually)

deLacombe primary, A,r = at= + bP a,b,m,n

secondary and

part of tertiary

Table 2. Some commonly used empirical creep equations.

One of the relatively simple equations that can be fit to the data that is collected is the

parabolic form:

A,,=a(time)" (1)

The constantscan be determinedby plottingthedataon log-logpaper and fittinga straight

line. Simple statisticaltechniques,such asleast-squarescurvefitting, can be used to find the

best fit. Constanta is the creep deflectionat 1 time unit. The slopeof the fittedline is the

constantm.

347
Another form of Equation 1 can be developedby takinglogarithms:

log(Acr)=log(a)+mlog(time) (2)

By plotting log (h,) as a function of log (time) the parameters a and m can be determined.

Again, because the transformed relationship is linear, simple straight-line fitting can be used

to obtain values for a and m. As shown in Figure 3, which was developed with data taken

from the test set-up as described in the procedure, the slope of the plot is m and the intercept

of the straight line is log a. In this case, m = 0.4298 and log a = -2.4. Thus, a =

0.00398 for use in Equation 1. Figure 3 was produced using a spreadsheet with a regression

function, and using the logadthims of the data shown in Table 1 as input. The R2 for this

regression analysis was 0.9365.

-1.6

-1.7-

-1.8-

-1.9-

<3

o) -2" _o

-2.1

-2.2 log a = -2.4 /"

/

/

-2,3

-2.4 _, " , , , ; , ' '

0.130 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

log t (min)

Figure 3. Relationship between log (A,) and log (time) for a spruce beam.

Notes to the Instructor:

1. The dimensions of the bending member or the magnitude of the weight are not critical of

themselves, but they should be designed to create an equivalent bending stress of about 1500

psi. The combination illustrated in this experiment results in a bending stress just over 1400

psi.

348
To determinebendingstressina simply-supportedbeamwith a single, concentratedload as

illustrated,use the followingformula(derivedfromthe flexureformula):

o=1.5 pL (3)

where:

o = stress(psi)

P = load (pounds)

L = spanlength (inches)

b = width of beam (inches)

d = depthof beam (inches)

2. Creep is affectedby severalfactors,includingthe stresslevel on the beam, the

temperature,and the moisturecontentof the wood. Additionalcreep tests can be conducted,

for comparison,by alteringthe loadlevel or conditionof the wood. Plywoodmight offer

anothermethodof comparison,sincethe graindirectionof test samplescan be easily

orientedwhen sawingthe samples.

3. While the NDS providesa singleload durationfactor(CD)relationship,it maybe

interestingto comparecreep effectsfor differentspeciesof wood. For example, hardmaple

has a muchhigher densitythandoes spruce. Be surethat all other factors(size of members,

moisturecontent,etc.) remain constant.

References:

American Society for Testing and Materials: Standard methods of testing small clear

specimens of timber. ASTM D 143-83. ASTM, Philadelphia, Pennsylvania, 1991.

Bodig, J. and B.A. Jayne: Mechanics of Wood and Composites. Van Nostrand Reinhold Co.,

New York, 1982.

Conway, J.B.: Numerical Methods for Creep and Rupture Analysis. Gordon and Breach,

Science Publishers, Inc., New York, 1967.

Criswell, M.E. and M.D. Vanderbuilt: Laboratory testing of wood and structural wood

products, in: Wood as a Structural Material. Dietz, A.G.H., E.L. Schaffer, and D.S.

Gromala, eds., Educational Modules for Materials Science and Engineering (EMMSE)

Project, Materials Research Laboratory, The Pennsylvania State University, University Park,

Pa, 1982.

National Forest Products Association: National Design Specificationfor Wood Construction.

NFPA, Washington, DC, 1991.

349

THE DEVELOPMENT OF MECHANICAL STRENGTH

IN A CERAMIC

MATERIAL DURING FIRING

L. Roy Bunnell

Materials Science Department

Battelle

Pacific Northwest Laboratories

P. O. Box 999

Richland, Washington 99352

Telephone 509-376-2799

and

Steven W. Piippo

Materials Science Technology

Richland High School

930 Long Avenue

Richland, Washington 99352

Telephone 509-946-5121

351
352
DEVELOPMENT OF MECHANICAL STRENGTH IN A CERAMIC MATERIAL FIRED

AT SEVERAL DIFFERENT TEMPERATURES

L. R. Bunnell

Pacific Northwest Laboratory, Richland, WA

S. W. Piippo

Richland High School, Richland, WA

Key Words: Ceramics, Extrusion, Modulus of Rupture, Strength Testing, Brittle Materials

Prerequisite Knowledge: This experiment was designed for high school students who have a

very limited background in ceramic materials, but could be used at the college level.

Objective: To teach students about: 1) the development of mechanical strength in a ceramic

material as a result of the firing process, and 2) about testing methods used for brittle materials.

Procedure: To begin, introduce the concept of brittleness, which is failure at very low values of

mechanical strain. Although ceramic materials can be stronger than some metals, the measured

strain at failure is very low, typically0.01 to 0.1% strain. This is because the typicallyionically

bonded ceramic cannot relieve the high stresses at inherent flaws by flow, as usually occurs in

metals and polymers. Cracks remain sharp and propagate through the material at high speed.

The ceramic article tends to break catastrophically. There are exceptions to this behavior, with

certain ceramic composites or new ceramics processed for toughness, but the generalization

holds true for glasses and traditional clay-basedceramics.

In this experiment, we will prepare clay-basedceramic bars of uniform circular crosssection by

extrusion. Then we will fire the bars at temperatures high enough to achieve high strength by

development of a glassybonding phase. Finally, the bars will be stressed to failure in a simple

testing machine. This will quantify the increase in strength as a function of firing temperature.

* Pacific Northwest Laboratory is operated by Battelle Memorial Institute for the U.S.

Department of Energy under Contract DE-AC06-76RLO 1830.

353
First, purchase some low-firingclaysuitablefor extrusionfrom your local hobbyceramic

supplier. Such a clay shouldbe free from large particleswhichwould cause tears during

extrusion. (The claywe used is of the same compositionas the slipused to make ceramicbells

for a presentation in NEW:93 [Bunnelland Piippo,1993]). Sincethe claywill be extruded,ask

the supplierto make the clayslightlyhigherin watercontentthanwould be used with a potter's

wheel. Use a simple,inexpensivehand-operatedextruderto extrude the clayto a uniform

circularcross-sectionabout2 cm in diameter. If the extruderdie has multipleholes of different

sizes, constructa cover for the sizesnot desired,to preventextrusionthrough those holes. Cut

the clay asit emergesfrom the extrusion die into approximately0.5 m lengths,straightenthem

as much as possible by rollingon a benchtop, and allowthem to air dry overnight at room

temperature. Then cut each claybar into segmentsabout 20 cm long by hacksawingabout 1/3

throughand carefullybreakingit. Scratchthe intendedfiring temperaturesnear one end of

eachbar. A minimumof thirtybars are required,whichallowsfor testingof five specimensat

each of five firing temperatures,plusfive barsto be testedwithoutfiring them. About ten extra

bars should be producedin case of mistakesor accidentalbreakage. For our claycomposition,

we used the followingfiring temperatures: 650,750 850, 950 and 1050C. Heat the specimens

to the firingtemperaturein aboutfourhours, hold at that temperaturefor 1.5hours,and allow

them to furnacecool.1 Specimensthat have been driedbut not fired should also be testedfor

comparison.

In order to test the strength of the ceramic specimens,several methods were considered in

terms of simplicityand validity of results. For instance, the direct application of tensile stresses

to a ceramic specimen is difficult. In order to obtain valid results, tensile specimens must

experience no bending loads. Another method, diametral compression of a right circular

cylinder is good in that the specimen is inherently self-aligning,but trimming the specimen faces

parallel is difficult and the force required to cause failure probably exceeds our measuring

1Depending on the size of the clay body being fired, steam formation could cause

specimens to explode during firing if the temperature increases too quickly. We did not

experience any difficultyat the specimen diameter used, but the problem could be avoided

by drying the specimens overnight at a temperature of about 90°C.

354
capability. Three-point bend testing of a uniformcross-sectionis a reasonable approach, and

the specimenis self-aligningif circularin cross-section.

For our testing,we built and used the simple testingmachine shown in Fig. 1 (cost less than

$50).2 Of course, any universal testing machine could be used. The failure of ceramics is

relatively insensitive to strain-rate effects, which permits us to apply the load at an uncontrolled

rate without introducing major error. Loading the specimensin three-point bending also

permits foreknowledge of the failure location (the center of the top of the test bar), and any

obvious surface flaws can be simplyplaced on the compression side of the specimens so that

they have a smaller influence on the results. Results in which the specimen did not fail near

the center of the test bar where stress is known should be ignored.

The size and loading conditionsfor specimensshould be chosen to minimize stored energy in

the test machine and specimen, so that fragments will not be thrown when the specimen

fractures. Also, the test setup we used would tend to throw fragments downward rather than

outward. As long as three-point bending is used and the breaking force is less than about 1000

N, a scatter shield is probably unnecessary. Perform a dry-run of the experiment, followingall

steps and checking for unexpected safety hazards. If it appears that fragments could be thrown,

the specimens could be tested while contained in polyethylene bags. During testing with our

machine, one person operated the jack and a second person read the force gauge.

During testing of the specimens, only the specimen diameter and peak load are measured.

When testing is complete, use these values in the equation for the maximum tensile stress

sustained by the bar:

S = PL/'n'r3 (I)

In the above equation, S is the maximum stress on the tensile side of the specimen (Pa), P is

2The designfor thistestingmachine was adapted from one built by Andy Nydam, a high

school Materials Science and Technologyinstructor at River Ridge High School in Lacey,

WA.

355
the breaking force (N), L is the distance between the two outer load points (m), and r is the

specimen radius (m). The maximum stress calculated by the above equation of traditionally

called the modulus of rupture in the literature. The stress values for any given specimen

condition will show scatter, which is typicalfor ceramic materials. (The fabrication methods

used for ceramics tend to leave cracklike artifacts, unlike the pouring of a molten metal.)

Average the strength values and calculate the standard deviation for each group of specimens

fired at a given temperature.

A plot of our results is shown in Figure 2. Note that the strength of the fired ceramic increased

at an accelerating rate with firing temperature. The strength increase is correlated with the

development of a glassybonding phase at temperatures above about 800 C, and the amount of

this bonding phase increases with temperature. (For a general discussion of ceramic materials

and the firing process, see Flinn and Trojan, Ch. 7, or Jacobs and Kilduff, Module 7.) The

ceramic thus becomes stronger as it is fired to higher temperature. If the claywe used is

heated another 100 C to 1150degrees C, the glassyphase is sufficientlyfluid and present at a

high enough volume percentage that the ceramic will deform or slump. As shown in Figure 2,

the standard deviation of specimen strength tends to increase with increasing strength.

However, the scatter in the data is no greater than about 20%, which is in the expected range

for ceramic materials,fabricated:'byunsophisticated methods. Careful measurements will reveal

that the cross section of each rod is not quite round, which could be a major source of error

since the radius is cubed in the equation used to calculate fracture stress. If the diameter is

measured at one point in the center and that point is marked, the specimen could be oriented

so that load is applied parallel to the measured diameter.

Note also that the values of breaking stress in Figure 2 are very high. This is an artifact of

testing by the three-point bend method, and is caused by the very small volume of material

stressed to the calculated maximum level. Bend testing generally overestimates the true tensile

stress as determined in a uniaxial tension test, by a factor of about three. This bias is of no

consequence for the purposes of this experiment, since failure stresses are used only for

comparison purposes.

SampleDataSheets: Nonenecessary.

356
Instructor Notes: There are many possible Variations of this experiment. For instance,

specimens could be fired for different lengths of time at the higher temperatures (above 800 C)

to study strength development as the glass has more time to form and flow. Intentional defects

could be introduced into the specimens, and oriented on either the tensile or the compressive

faces. The effect of defects will be much more evident on the tensile face. Round ceramic

rods subjected to a thermal shock test such as described in (Bunnell 1991) could be tested, and

the decrease in strength with thermal shock damage could be measured.

References:

1. Flinn, R. A.; and Trojan, P. K.: Engineering Materials and Their Applications, Third Ed.,

Houghton Mifflin Co., 1986.

2. Jacobs, J. A.; and Kilduff, T. F.: Engineering Materials Technology, Second Ed., PrenticeHall, 1994.

3. Bunnell, L. R.: Thermal Shock of Ceramic Materials, presented at National Educators"

Workshop, Update 1991, NASA Conference Publication 3151, 1992.

4. Bunnell, L. R.; and Piippo, S.W.: Property Changes During Firing of a Typical Porcelain

Ceramic, presented at National Educators' Workshop: Update 1993, NASA-Langley,

1993.

Sourcesof Supplies:

1. EM210 clay composition,made from 50% Talc, 50% Ball Clay, available from Laguna

Clay Co., City of Industry, CA 91746

2. We used a Standard Clay Hand Extruder, made by North Star Equipment, PO Box 189,

Cheney,WA 99004.

357
I I I I

I I I I

I I Steel Selected for Stiffness I

I I

I

[ _ t__l

Bathroom Scale --- _ 1 t,

1 -20 mm

I "© Specimen O. I

_12 mm

Steel Roller

i crew

Jack

= --- Steel Base

--_ _-- _

L.J LJ

I S0om I

39409033.2

Figure 1. Testing machine used to load ceramic test bars in three point bending.

358
-- 500

70--

60 --

-- 400

-- 100

10

0 I I 0

500 1000 1500

FiringTemperature, °C

39409033.1

Figure 2. Strength of ceramic bars, as a function of firing temperature.

359

WATER DROP TEST FOR SILVER MIGRATION

Ted Gabrykewicz

EngineeringTechnologiesand ScienceDepartment

HockingCollege

3301 HockingParkway

Nelsonville,Ohio 45764

Telephone 614-753-3591 ext. 2403

361
362
WATER DROP TEST FOR SILVER MIGRATION

Ted Gabrykewicz

Instructor

EngineeringTechnologies and ScienceDepartment

HockingCollege,Nelsonville,Ohio 45764

Key Words: Silvermigration,thick film, dendrite, electrolyte

Prerequisite knowledge: Knowledgeof precious metals and familiaritywith electronic

circuitsis helpful.

Objective: To observe silvermigrationin a microcircuit application. To measure the

effectivenessof a silver alloy for reducing silvermigration.

Equipment:

1. 9 and 1.5 volt batteries

2. microscope, 10 to 30X

3. voltmeter

4. two electrical leads each with an alligator clip and probe tip

5. thick film test patterns with silver conductors

6. thick film test patterns with silver alloy conductors

7. DI water

8. stop watch

9. eye dropper

10. beaker, 50 ml

Introduction:

At room temperature silverhas the highestelectrical conductivityof anymetal, but the high

cost of silverprevents its use for many commercial applications. Silverdoes become

economicallyfeasible for microelectronic applications,because the quantity of silverrequired

is small. One microelectronic technology that uses silverfor circuit conductors is Thick Film.

This technology uses the silk-screeningprocess to produce miniatureelectronic circuitsfrom

conductor, resistor, and glass compositions. These materialsare prepared as inks and a

squeegee forces the ink through openingsin a finemesh screen and deposits it onto a

substrate. Miniature circuits consistingof conductors, resistors, and capacitors can be

created with thistechnology.

Unfortunately, a 100 percent silver conductor can not be used in all electrical applications.

Silver can be easily oxidized or reduced. For example, silverin contact with vulcanized

insulation can migrate and create conductor paths within the insulationwhich greatly reduces

363
insulation resistance. Silvercan also migrate in a thickfilm microcircuit and only requiresthe

presence of moisture and a sufficientDC voltage gradient.

Moisture will form on most commercial circuits as a result of condensation from changing

humidity and temperature conditions. Although the moisture may evaporate, the effect of

silver migrationis cumulative. The silverwill beginmigratingagain with the next instance of

condensation on the circuit. The finalresult can result in an electricalshort between the two

conductors.

This problem is an exampleof metallic corrosion, because a silver atom loses an electron

and becomes a positive ion. An electrolyte consisting of water and positive silverions is

created. The silverions acquire electrons at the negative electrode and metallic silveris

deposited at the negative electrode. Thus, silver dendrites grow fromthe negative electrode

to the positive electrode. Figure 1 shows dendrite growth between two conductor lines.

ConductorLine

( positive)

Conductor Line

( negative )

Figure 1. Dendrite Formation between

conductor lines.

The distancebetweenconductorlines,significantlyaffectssilvermigrationinmicrocircuits.

Forthickfilmcircuitsthe spacingbetweenlinescanbe lessthan0.2mm,andthisresultsin an

electricfieldthat issufficientformigration.Increasingthe voltageor decreasingthe spacing

betweenconductorlinesincreasesthe rateof silvermigration.

Othermetalssuchas copper,gold,platinumandaluminumdo not experiencemigrationwith

just wateranda DCbias,becausetheydo not readilyformpositiveionsin water. However,

thesemetalshaveothermaterialproblemsor are too expensiveforthickfilmcircuits. To

resolvethe silvermigrationproblem,materialscientistsalloysilverwith otherprecious

metals.The additionof 2%platinumor 15%palladiumbyweightwillsignificantlyreduce

the rate ofsilvermigration.

A common test that determinesthe resistance of a thick filmconductor to silvermigration is

the water drop test. Thisis an accelerated test designedto generate dendrites in a short

period of time. The test consists of placing a drop of water on two conductors that are < 0.2

mm apart. A DC voltage is applied at the test pads, and the time for the dendritesto bridge

364
the gapisrecorded. Figure2 showsan exampleof a typicaltest pattern. The dendrites

shownpreviouslyin Figure1will formin the migrationarea.

[_ Test Pad MigrationArea

i Test Pad

Figure 2. Migration test pattern.

Procedure:

1. Initial Preparation - Clean the 50 mlbeaker and addN20 ml of distilledwater.

Record the voltage of the battery and check lead continuitywith the voltmeter.

2. All SilverConductors - Attach the alligator clipsto the test pads of the thick film substrate

with the silver conductor. Place the sampleunder the microscope so that it islevel and bring

the migrationarea into focus. Add a drop of DI water over the migrationarea; make firm

contact to the 1.5 volt battery with the tip of each probe; start the stop watch andwith the

microscope observe the test area for dendrite formation. Do allsamples on the test pattern,

and record the average time required to bridge the gap between the conductors.

3. Silver AlloyConductors - Repeat the procedure in step 2 for the silver alloy samples.

4. Repeat steps 2 and 3 with a 9 volt battery and record all results in a table similarto

the one below.

Table I. Sample Data Summary

Conductor DCVoltage, MigrationTime,

Sample AlloyingMetal volts sec Comments

Group A all Ag 1.5 15

GroupA allAg 9 5 HigherDCvoltage

Group B Ag/Pd 1.5 40 Pd alloying

Group B Ag/Pd 9 20 Pd alloy & higher volt.

365
Notes to the instructor:

1. The thick film migration test patterns can be obtained from the author at Hocking

College, 3301 Hocking Parkway, Nelsonville, OH 45764. Additional potential sources

are:Engelhard Corp., Precious Metals Coating Group, 1W. Central Ave., East Newark,

NJ 07029 and E.I. DuPont, Microcircuit & Comp. Materials Div., Barley Mill Plaza,

P30.2362, Wilmington, DE 19898.

2. The 9 volt battery mayproduce excessivegeneration of bubblesthat can break up the

dendrites and prevent them frombridging the gap. If this occurs you may have to use

two 1.5volt batteries in series or a 0 to 15volt DC power supply.

3. The generation of bubblesresults from the electrolysisof water and represents the

production of hydrogen or oxygen gas depending on the pH of the water.

4. Keepthethickfilmsubstratesin a plasticbagto reducetarnishing.Do notstorethemin

a paperenvelope,becauseitmaycontainsulfur.

5. Hold the sample by its edge to prevent salt contaminationfromyour fingers. The salt

will increase the rate of silvermigration.

6. Be sure the beaker is clean and free of contaminants or fastermigrationstimes maybe

incorrectly obtained.

7. The spacingbetweenthe conductorsmayvaryfor differentsamplelots. Thiscould

resultin significantlydifferentmigrationtimesfortwo lotsof the samecomposition.

8. Samples canbe reused by thoroughly cleaningthe migrationarea with a rubber

eraser.

References:

I. McGraw-Hill Encyclopedia of Science attd Technology,sixth ed., McGraw-HillBook

Co. Vol. 16, 1987, pp. 420.

366
INEXPENSIVEEXPERIMENTSIN CREEP

AND RELAXATIONOF POLYMERS

Kopl Halperin

Charles Eccles

Brett Latimer

Department of Mechanical Engineering

School of Engineering and Engineering Technology

Pennsylvania State University-Behrend

Erie, Pennsylvania 16563-1701

Telephone 814-898-6153

367
368
Inexpensive Experiments in Creep and Relaxation of Polymers

Kopl Halperin, Charles Eccles and Brett Latimer

School of Engineering and Engineering Technology

Penn State-Behrend

Erie, PA 16563-1701

Key Words: creep, relaxation, polymers, plastics

Prerequisite Knowledge: Some knowledge of solid mechanics/strength of materials/mechanical

properties of materials.

Objective: To show that the mechanical properties of plastics are dependent on time. To alert the

student to the design implications of putting plastics under constant loads.

Equipment:

1. Tensile specimens ("dogbones") of various plastics

2. Watch with second hand

3. Notebook to record data

For relaxation experiment

4. Tensile test machine

For creep experiment

5. Weights from bar-bell set

6. Small c-clamps

7. Metal wire

8. Ruler

Introduction:

Plastics are not often used for applications that must support a constant applied load. The reason for

this is simple - under constant load, any plastic will deform if left for a long enough time. This will

happen even at low loads and even at room temperature. Ceramics, wood, and most metals do not

deform under the same circumstances. It is this type of deformation of plastics that limits the

potential market for recycled plastic lumber. On the other hand, Higgins [1] points out the

deformation of a plastic under its own weight is not so great that a plastic raincoat hanging in the

closet winds up touching the floor.

The deformation of materials under conditions of constant load cannot be seen on a stress-strain

curve, although it does explain why the speed of loading is important in plastics. To see it requires

measurement of explicitly time-dependent behavior. There are two different time dependent behaviors

that can be measured - creep and relaxation.

369
Creepoccurswhen a materialunderconstantloaddeformsovertime. Relaxationoccurswhen stress

fallsoff in a materialheldat constantextension. In the labcreep and relaxationare measured

separately. But in the real world, creep and relaxationtypicallyoccurtogether. Both are aspectsof

viscoelasticity,the overridingmechanicalbehaviorof plastics[2;3].

A Creep Experiment:

There are commercialdevicesavailableto measurecreep. These are costly, and if only one is

availableit takesa long time to get results. For studentuse, a simpleexperimentwhichmeasures

manysamplesin parallel is moreuseful. The experimentshownhere measuresmany samples

simultaneously,at low cost.

Procedure:

Procure Tensile Dogbones of a Range of Plastics

Ours are made by students in the Plastics Engineering Technology program at Penn State-Behrend as a

part of their studies in injection molding. They are thus available to us in large quantities at no cost.

People who don't have this luxury may wish to cut specimens out of food containers (after eating the

food, if you want our advice) or defunct shower curtains, or any available stock. It is possible to

meet the ASTM standards by any of these methods [4;5]. It is always a good idea to meet the

standard if possible, both to ensure a good test and to introduce students to the use of the

relevant standards.

Choose, or make, dogbones of small enough cross-sections so that barbell weights result in stresses in

the 1000 to 3500 psi range. ASTM D 638 type V are ideal [4].

It is best if all applied stresses are the same. This can be achieved by having uniform weights and

cross-sections, or by varying the cross-sections to go with the available weights. An optimal

experiment might be to use a 1/8 inch square cross _ectionwith a fifty pound weight, for a stress of

3200 psi.

Preparea notebookpage with twocolumns:time and length. The lengthshouldbe the lengthof the

gage area.

Attach c-clamps to top and bottom of specimen, on the wide parts of the specimens. Real grips would

be better, but the c-clamps are close enough to the standard and much less expensive.

Hang the top end of the dogbone by a metal wire from a rigid support.

Hang the weight by a metal wire from the c-clamp attached to the bottom end of the dogbone.

Immediately measure the leligth of the specimen.

370
Continueto takemeasurements,every 15sec. for the firstfive minutes,every five minutesfor the

first hour, at leastonce a day for as long as desired. The standardexperimenttakesthe samplesto

creeprupture [5]. We foundtwo weeksto be sufficientto demonstratecreep; even one day will give

enoughdata for discussion.

Sample Results:

We usedone sample each of five very different plastics. In order of increasing toughness, these were:

polystyrene (PS), acrylonitrile-butadiene-styrene(ABS), polypropylene (PP), a nylon, and

polycarbonate(PC). For this sample experimentno effort was made to make the stresses uniform.

The samples were ASTM D 638 Type I, machineddown to narrower cross-sections [4].

The sample dimensions, weights used and stresses are given in table 1.

Table 1: Sample Dimensions, Weights and Stresses

Cross-Section

Material area, sq. in. Load, lb. Applied Stress, psi

Polystyrene (PS) 0.017 25 1500

Acrylonitrile- 0.030 30 1000

butadienestyrene (ABS)

Polypropylene (PP) 0.015 15 1000

Nylon 0.027 40 1500

Polycarbonate(PC) 0.013 40 3000

The data are presented in Figure 1. The experiment was run for a little less than two weeks. These

results are sufficient to establish that the experiment works, and that the experiment can be used to

show that different plastics have different creep behaviors. Given that the samples were not all at the

same initial stress, it is not easy to say anything further about the plastics. Creep rate

is highly dependent on stress [1]. It is easy to recommend better practice when performing this

experiment. Most of these recommendations are incorporated into the experimental procedure, above.

Further recommendations are: to do at least two samples of each material. One set of samples could

be at 1000 psi, the other at 3000 psi. Separate plots could be made of:

1. All the samples at 1000 psi

2. All the samples at 3000 psi

3. A single material at 1000 psi and 3000 psi.

371
This would enable comparison of creep behavior across materials, and of the effect of increased stress

on each material. If the experiment was done carefully enough, it should be possible to calculate the

creep constants if the instructor so desired [7].

The Relaxation Experiment:

Unlike the creep experiment, this experiment has been run in the materials lab at Penn State-Behrend

for five years, over at least 50 lab groups. It is thus well-established.

Procedure:

Procure Tensile Dogbones of a Range of Plastics

Use the same materials as in the creep experiment. Standard dogbones of any shape will work. Our

dogbones are ASTM D 638 Type I, gage area 1/8" x 1/2", gage length 2.25 " [4]. Table 2 lists all of

the materials we have used. ASTM practice [6] allows machined from existing materials; the samples

do not have to be dogbones.

Table 2: Polymers used for Relaxation Experiment, with Approximate Failure Stresses

Material Failure stress, psi Type of failure

Elastomers < 1600 Cannot support greater stresses

Polyethylenes < 4800. Cannot support greater stresses

Polypropylene < 4800 Cannot support greater stresses, or

pulls apart

Recycled PP Slightly less

Acetates < 4800 Brittle

Polystyrene < 4800 Brittle

ABS < 6000 Brittle or pulls apart

Nylons < 8000 Pulls apart

Polycarbonate > 9600 Pulls apart

Measure and record the specimens

Use a Tensile Tester

The ideal tester is accurate to one pound in a range of zero to one thousand pounds, for the gage cross

section we use. This gives a stress range of zero to 16000 psi. Our tester has a maximum of 500

pounds. As is shown in table 2, this makes it incapable of breaking polycarbonate, but more than

372
sufficient to break every other plastic we have used. The ideal tester would have computer data

collection. The steps that follow assume hand collection of data.

Prepare a notebook page with two columns: time and force. The force is the raw data from the tensile

tester.

Install a Specimen in the Tester

Increase the force until a stress of around 3000 psi is reached. Then stop the motion of the

crossheads. A constant strain has now been applied, and the stress is expected to fall off. 200 Ibs on

our dogbone cross section gives a stress of 3200 psi. Generally elastomers cannot reach this stress.

In all other polymers, this stress is less than the failure stress, but high enough that some interesting

relaxation behavior should be seen.

Immediately Take a Measurement

Continue to take measurements, every 15 sec. for the first five minutes. Even three minutes gives

enough data for useful results. If desired, the last sample can be left in the tester until the next lab

meeting. The shape of the relaxation curve does not change, nor does it ever approach an asymptote.

Stressjust continues to fall. The longest time we have let a sample relax is two weeks.

Leaving the sample in the tester, increase the stress. We generally increase to 250 Ibs (4000 psi) then

300 lbs (4800 psi) for each sample, and go on to 400 lbs (6400 psi) and 500 lbs (8000 psi) for those

plastics which can support those loads.

In theory it may be better to use a new sample for each stress, but we have found that the differences

between samples of the same batch of the same plastic are as large as the errors that may be

introduced by just continuing to use the loaded sample. And using the loaded sample saves time.

Repeat the procedure with each material.

Report:

The lab report requires the students to plot:

1. All the plastics at one stress, and

2. One plastic at three or more different stresses.

Figure 2 shows a sample result of stress relaxation for five plastics at one initial stress. The students

are also required to calculate a relaxation time for all the materials. For example, the half-time of a

material isthe time it takes for the material to relax to half of the initial stress. As this is never

reached in this experiment, the students are required to calculate the time it takes for the stress to fall

to 95% of its initial value. For example, at an initial stress of 3200 psi, the time at which the stress

reaches 3040 psi is reported. A table of these values for all plastics tested is reported by our students.

This gives some measure of the relative relaxation resistance of the plastics. If the instructor so

desired, the students could be asked to calculate the relaxation constant which Flinn and Trojan [8]

373
and Shackleford [9] call the relaxation time, which is the time it would take for the stress to fall to

0.37 (= l/e) of its initial value.

Discussion

This experimentis quite successfulin showingthatstressbehaviorof plasticsistime-dependent.The

studentsare askedto write oneparagraphaboutthe importanceof thisresultfor design;this has been

a successfulexerciseforthem.

Of the two properties,creep and relaxation,creep is more important. It isfound in practicallyall

introductorymaterialstexts at every level- technology[1;2], design[7;8], materialsscience[9] and

evenphysics[10]. In practice it is easierto picturea constantloadapplicationthan a constantstrain

one. The studentshavebeenaskedto explainthe significanceof relaxationfor creep. This has not

beenvery successful. It is easy enoughto statethatboth are non-steady-statematerialresponses. But

for the purposesof actuallyseeingcreep, it is necessaryto performa creep experiment.

Conclusions

Two experiments have been presented. One has been used for many lab sections with great success;

the other is newly developed. Both should be useful for explaining some aspects of design with

pl_tics.

In addition, they can be used as inexpensive analogues for metals experiments. Because of our

proximity to a cheap source of plastic experimental pieces, we use plastic samples for much of our

materials testing. This has proved quite useful for explaining the range of behaviors across various

materials classes. There are brittle plastics, like polystyrene (PS). There are also tough plastics, like

polycarbonate (PC). The tensile test results for PS look like those for a ceramic. The tensile test

results for PC look remarkably like those for low carbon steel. In both cases the results for plastics

are shifted down to lower stresses and out to higher strains. Similarly, plastics impact testing is much

cheaper than metals impact testing. The same range of behaviors can be shown, including sensitivity

to forming methods. Of course, plastics forming methods are not the same as heat treating.

Creep and relaxation in metals are high temperature phenomena, but room temperature is a high

temperature for a polymer. All polymers melt or burn below 500 celsius [2]. Most, including all of

those used here are destroyed below 300 celsius. Thus room temperature is above the rule of thumb

temperature for creep and relaxation behavior in plastics. If one uses a rule of thumb of 1/3 of the

melting point in degrees Kelvin as the onset of creep [7], a melting point of 300 celsius gives creep

being important at any temperature above -80 degrees celsius. Thus plastics will always creep and

relax in use.

This explainswhyplasticsare notpresentlygood for structuraluses. Creep and relaxationwill

alwaysleadto failureof plastics underconstantloads.

374
References

1. Higgins, R.A.: Properties of Engineering Materials. EdwardArnold, London, 1977.

2. Jacobs, J.A.; andKilduff, T.F.: Engineering Materials Technology. Prentice-Hall,

Englewood Cliffs, NJ, 1985.

3. Young, R.J.: Introduction to Polymers. ChapmanandHall, London, 1981.

4. ASTM D 638 - 89: Standard Test Methodfor Tensile Properties of Plastics. American Society

for Testing andMaterials(ASTM), Philadelphia, 1990.

5. ASTM D 2990 - 77: Standard Test Methodfor Tensile, Compressive, and Flexural Creep and

Creep-Rupture of Plastics. American Society for Testing andMaterials(ASTM),

Philadelphia, 1990.

6. ASTM D 2991 - 84: Standard Practice for Testing Stress-Relaxation Plastics. American

Society for Testing and Materials (ASTM), Philadelphia, 1990.

7. Ashby, M.F.: Materials Selection in Mechanical Design. Pergamon Press, Oxford, 1992.

8. Flinn, R.A.; and Trojan, P.K.: Engineering Materials and Their Applications, 3rd ed.

Houghton Mifflin Co., Boston, 1986.

9. Shackleford, J.F.: Introduction to Materials Sciencefor Engineers, 2nd ed. MacMillan

Publishing Co., New York, 1988.

10. Lovell, M.C.; Avery, A.J.; and Vernon, M.W." Physical Properties of Materials. Van

Nostrand Reinhold, New York, 1976.

375
Fig. 1"

Results of sample creep experiment

5 plastics, 1000 to 3000 psi

160

140- _-E -_--__4=_- _-_-_'_=_- _''_A Nylon

._i./" 120- _-E_-__--_

E_r -4_- .,i_-,_°" -- - Po!ypropytene

._a.o.100-_ .__-.&---'_r_

i

-_._ 80 -_' __a, _-_ Polystyrene

60- _--_-

,_-_:" Polycarbonate

40- ,_

20" • . . -,. o,..,. ABS .............. _............ -..... _ .! _ _'_ ._-_.:$, .::_..:'i,, .:i_,

o _, 4- 6 8 1'0 12

Time, days

376
Fig. 2:

Results of sample relaxation experiment

5 plastics at same initial stress

3200 "-'-

",_ ..... - -,. -,- .,. _ .... _ -,- _ _ .._

3100 ,,_J_--..... ._"'*"'_-" _=_ .........................................................................................................Nylon

_, _ --______ ==___ ...

3000 ...._ ........................................................................................ _....-T_...._.__._ .........................

_ 2900- _"_ '__ T =--_=--_--_" PS ................... _'-_"-"_E ..................... ........................................................................................................

o_ ---_m.___................................................

+

_- .......................... -_

_._°°°........................ iiiiiiii iii _212................... .................+_°

_ 2700 ......................... -._ L._._i_ ABS

2600 ........................................................................................................ :................................. '-:_'__:........................

---_.______ _

'2500 ................................................................................................................................................PP

24"00 0 I ' i i I i ' _ i I I _ I i I 4 I I I 5

Time, minutes

377

CONCRETE REPAIR APPLICATIONS

Leonard W. Fine

Department of Chemistry

Columbia University in the City of New York

Havemeyer Hall

New York, New York 10027

Telephone 212-854-2017

379
380
CONCRETE REPAIR APPLICATIONS

Using High Molecular Weight Methacrylate Monomers

LeonardW.Fine

DepartmentofChemistry

ColumbiaUniversity

NewYork,NewYork 10027

Key Words: High molecular weight methacrylatemonomer, free radical polymerization,

catalysts, concrete repair.

Prerequisite Knowledge: Basic organic chemistry and general chemical principles. Some

understanding of polymers and polymerization reaction chemistrryhelpful but not necessary.

Objective: To provide a simple demonstrationof how high molecular weight methacrylate

monomers can be used to create a polymer compositethat can be used successfully in concrete

repair applicationssuch asf'lllingcracks in sidewalks and roadways, and especially in solving the

pothole problem that plaguesmany municipalitiesduring latewinter and spring each year.

Materials and Equipment:

1. Sand (Pettinos No. 2 and 4)

2. Silica flour 120

3. Titanium dioxide (DuPont)

4. Cobalt acetyl acetonate

5. High molecular weightmethacryaltemonomer (Rohm& Haas)

6. Cumene hydroperoxide (Lucidol)

7. Make-shift wooden block and concrete forms

8. Disposable tongue applicators(for stirring)

9. Tissue wipes

10. Safety goggles and Platex-styled gloves.

Procedure:

Cumenehydroperoxide(73%)is thoroughlymixedwith the high molecularweight

methacrylatemonomerselected.The freshly catalyzedmonomeris quicklyaddedto the dry mix of

allthe other componentsin a disposablepolyethylenecontainerofsuch size thatitis aboutonequarterfilled.The resultingslurryis stirreduntilthe drymix isthoroughlywettedoutwith the

381
catalyzedmonomer. Test samples are thencast in miniatureconcrete molds or are filled directly

into cracks in previously prepared concrete samples.Bulk cure is complete in 1-2 hours but surface

cure takes 3-4 hours due to the inhibitionof free radicalpolymerizationreactions by oxygen in the

air. For the purposes of a lecture demonstration,an accelerator can be added which effects cure of

the bulk polymer in 5-10 minutes.

The actual mold that we have used to simulate a pothole consists of a 3X3X1 inch Lucite

frame mounted an a somewhatlarger piece of concrete. The wetted mix is spooned into the frame

with the disposable wooden applicator and "evened"off. It is then allowed to stand until cured.

Since the surface will be uncured, a Handi-wipe canbe used to dry the residual monomer before

testing. Stress analysis and crack length can be used to evaluate the differentmonomers.

For our immediate purposes,the monomer that will be used is dicyclopentadienyl

ethoxyethylmethacrylate. It is especially interestingbecause of the chemistry of its cure. Because

of its low volatility, it is an excellentmonomer for classroom demonstrations.It is easily

synthesized.

Notes to the Instructor:

1. All of the above items are commerciallyavailable.Generaltoxicity of all materials,including the

monomers, islow. Suitablemonomers can be purchased from several differentsources or

synthesized from easy-to-followprocedures available in the literature.

2. To visually demonstrate the strength of the material before an audience, use a hammer to

violently stress the material on the side of the frame or directly on the surface of the cured

polymer. Both tests willshow the repair to adhere strongly to the oldmaterial, and in most

demonstrationsto be strongerthan any originalsample.

382
GENERAL MECHANISM FOR THE CORROSION 

OF REINFORCING STEEL IN CONCRETE. 

Salt Cryrtal Growth and Alternate Longitudinal Crack: Path for Easy Penetration ot 

Freeze and Thaw Cycles Promote the Corrosive Agents. 

Formation ot Crackr. 

LOW ALKALINE CONCRETE , , 0 . . . 0'. . ' 0. '. : . ,.J ; 

0.. .'o .. 0.. . . . .. . ... . 'kte ot Penetration Depend. on Permeability of ' Concrete. Penetration ot C02 Causer 

0% H20, NaCl Inhibit the Porsibility Carbonltation ot Concrete, Lowering the'pH. of Sell-limiting Corrosion 

Expensive Forcer Created by the Corrorion 

Product Promote the Cracking and Spalling 

Initially Rust Scale Formr at Transverre 

Crackr. The Expansive Forcer Created 

Promote Longitudinal Cracking it C/D 

End View ot Embedded Bar - Ratio ir Small. 

, . 0 

HIGH ALKALINE CONCRETE 
STRENGTH/ WEAKNESS COMPARISON 

OF CRACK REPAIR MATERIALS 

PROPERTY 

SET TIME 

BULK CURE 

LOW TEMPERATURE CURE 

VISCOSITY 

TOXICITY 

ADHESION 

VOLATILITY 

SUBSTRATE PREPARATION 

FLAMMABILITY 

ODOR 

HMWM EPOXY MMA 
TYPICAL MECHANICAL PROPERTIES 

OF HMWM POLYMER CONCRETE 

MONOMER MONOMER MONOMER 

1540 1630 1680 

COMPRESSIVE STRENGTH, PSI 9000 7200 5900 

SHEARBOND ADHESION, PSI 735 900 650 

TENSILE STRENGTH, PSI 1725 1100 800 

FLEXURAL STRESS, PSI 2500 3000 1600 

FLEXURAL STRAIN, IN/IN 0.002 0.0 13 0.043 

FLEXURAL MODULUS, MM PSI 1.6 0.7 0.3 

GLASSFRACTUREEXPERIMENTFOR

FAILUREANALYSIS

CharlesV. White andKathrynForland

GMI Engineering andManagementInstitute

1700West Third Avenue

Flint, Michigan 48504-4898

Telephone 810-762-7884

387
(Paper presented by Kathryn Forland)

388
GLASSFRACTUREEXPERIMENTFOR

FAILUREANALYSIS

CharlesV. White

GMI Engineering& ManagementInstitute.

Flint,Mi.

Key words: Fracture surface analysis, failure analysis, glass

Prerequisite knowledge: basic failure mode analysis and simple

observation techniques

Objectives: 1)To provide the student with a learning experience in

which they analyze a failure in a 2-4 hour period, and are able to

verify their analysis with the people who have created the failure. 2)

to learn to "read" a glass fracture and map the fracture path.

Equipment:

1. Drinking glasses with smooth sides approx. 60mm dia. by

150mm tall

2. 4-6 Ziploc quart size freezer bags

3. Safety glasses

4. Students dressed properly: long pants, shoes, shirts and long

hair contained

5. Clear plastic tape

6. China markers or marking pens which will write on glass and not

smear

7. Lab tongs

8. Several sheets of heavy brown wrapping paper.

9. 50mm wide masking tape

10. Hand held magnifiers 3X and 10X

11. Reference material pack (see bibliography)

12. Flashlight

Introduction:

The analysis of a failure involves proper procedure, careful study of

the details and documentation of the facts. Often it is difficult for the

student to fully appreciate the care and patience necessary in the

examination and analysis of a failure. Secondly the student rarely

389
sees an example in which he/she can do an actual analysis and get

a definitive answer at the end of the exercise.

The idea of this exercise is to give the student practice in "reading

fracture" surfaces and an appreciation for the care which is required

to conduct a complete failure analysis.

Procedure:

This exercise requiresthe studentto followa procedurewhichwill

minimizethe possibilityfor injury.

Safetyglassesare to be worn duringthe entireexercise.

Each groupof students2-3 are givena drinkingglass. This glass is

placedin a plasticbag andsealed. Make sureto get allthe airout of

the bag. The entireparcelisthen placedintoa secondplasticbag

whichis sealed afterremovingthe air.The studentsare then

instructedto break the glass.Studentsare allowedto breakthe glass

anyway they wantto excepthighenergycompression.For example,

usingan arbor pressto crushthe glasswilltendto powderthe glass

and make it impossibleto analyze. Forthispart ofthe exerciseeach

groupworksoutof siteandear shotofthe othergroups.This is

necessaryfor securityindivulgingthe methodof breaking.At no

time during this period are the glasses removed from the plastic

bags. Shouldthe bags be damagedduringthe exerciseadditional

bagsare providedto carrythe contentsbacktothe worktables.

The work area is covered with a sheet of heavy wrapping paper. The

edges of this paper are folded to form an enclosure and taped to the

table. The bags with the broken glasses are placed on the paper.

When all the students have returned the glasses to the work area the

groups are assigned to a glass they have not broken.

Safety:

At this point the instructor demonstrates how to select and clean the

glass fragments before beginning the analysis. The bags are opened

and using lab tongs the larger pieces are removed from the plastic

bag. Each piece is brushed with a piece of tape to remove the small

particles of glass which would adhere to the surface. This procedure

is similar to removing lint from a coat. Once the pieces are cleaned

they are collected on the paper in an area away from the cleaning

area.

390
When all the larger pieces h_ivebeen removed from the bag and only

the fines remain, the bag is sealed and the work area is cleaned

using the same technique that was used to clean the glass pieces.

The teacher should again remind the students of the safety

requirements.

Analysis and reassembly.

The students are now allowed to proceed with the analysis using the

reference material which they have been given. It works better if the

reference material has been distributed to the students prior to the

class so they can read it and become familiar with the fracture

surface pictures. Students examine the individual fractured pieces,

noting the nature of the fracture. From the references the student can

"read "the fracture surface and determine those sections which are

areas of fast and slow fracture. In addition one can determine the

direction of the break by reassembling the glass with clear tape.

The following illustrations are typical of some of the features which

are definable in the surface of the fractured edge.

Crack propagation

-- f

high speed/energy low speed/energy

Direction

Bending at edge bending at center

Fracture origin

-------- mirror

// L\ \_.__ hackel

391
The reassembling of the parts of a fracture is a violation of the

principles of failure analysis. This breach of procedure, explained in

the context of a learning experience usually satisfies the harshest

student critic. In the reassembly, each piece is examined by eye and

or low power magnification. The pieces are handled with lab tongs

and only when absolutely necessary are they manipulated by hand.

Each side of the piece is marked with an arrow indicating the

direction of the fracture path and a letter for s for fast or slow

fracture mode. This process is carried out on all the pieces for each

fracture surface.

When this procedure is completed the reassembly is begun. This part

of the process takes about 1-1.5 hr.

Upon completing the assembly or that portion which can be

completed, the student is asked to determine the mode of failure and

make an oral presentation to the class. After the analysis group

finishes its presentation the breaking group presents how they

actually broke the glass. A class discussion follows on how the

method and analysis differ.

Data:

The photo in Fig.1 illustrates the final product of the reassembly. It

can be seen that the markings indicate not only the direction but the

speed of the crack propagation.

Instructor notes:

This experiment is fun for both the students and the instructor. It

teaches patience and the necessity for careful procedure and

cooperation among the group members. I use this experiment in my

Failure Analysis class which is a Sr./grad (573) class. The students

are mature and understand the safety precautions necessary for the

success of this kind of exercise. These students must still be

cautioned about the potential hazards throughout the exercise.

Comments would be appreciated cvwhite@beretta.gmi.edu

392
Figure 1.

393
References:

1. Stratton, D. R., CPP,: Reading the Clues in Fractured Glass.

Security management, Jan. 1994, p. 56.

2. Preston, F.W.: Bottle Breakage - Causes and Types of

Fractures, The Study Course on Mechanical Properites of

Glassware with Particular Reference to Glass Containers.

The Bulletin of the American Ceramic Society, February 1939,

p. 35.

3. Orr, L.: Practical Analysis of Fractures in Glass Windows.

Materials Research and Standards, January 1972, p. 21.

4. Preston, F. W.: The Propagation of Fissures in Glass and Other

Bodies With Special Reference to the Split-Wave Front.

Presented at the Annual Meeting, American Ceramic Society,

Cleveland, Ohio, February 1931, p. 419.

5. Murgatroyd, J.B., B.A., F.S.G.T.: The Significance of Surface

Marks on Fractured Glass. Presented at the Sheffield

Metting, Journal of the Society of Glass Technology, June

17th, 1942, p. 155.

6. French, M.A.: How to Analyze Tempered Glass Fracture. Glass

Digest, September 15, 1980, p. 50.

7. Nichols, R. T.: How to find the Cause of a Windshield Crack.

Glass Digest, March 15, 1989, p. 56.

394
IMPACT OF FLAWS

JoDee Daufenbach

and

Alair Griffin

Lone Peak Engineering

12660 S. Fort Street (950 E.) Suite Y

Draper, Utah 84020-9362

Telephone 801-553-1732

395
396
IMPACT OF FLAWS ON STRENGTH

JODEEDAUFENBACH AND ALAIR GR!FFIN

LONE PEAK ENGINEERING,INC.

DRAPER,UTAH

84020

Key Words: Impact of flaws, laminated object manufacturing, structural ceramics

Prerequisite Knowledge: Knowledge of basic structural ceramic concepts is helpful but not

necessary.

Introduction and Objectives

The purpose of this laboratory experiment is to demonstrate the impact of flaw size and

geometry using the table-top test unit illustrated in Figure 1. Using this kit, a professor can

dramatically illustrate the impact of flaws on load-at-failure for specific materials.

Ideally, high-technology materials should be flaw free. Realistically, flaws will always be

present. These flaws should have a significant impact on the strength of a material and its

suitability for particular production processes.

The material used in this test-apparatus is a green (un-fired) ceramic sheet. These sheets are

flexible and are prepared from alumina ceramic powder and polymers. During the experiment

students will test sheets that have dimensions of 3.8 x 7.6 cm. Three sets of sheets will be

tested. Two sets contain different size flaws that have been cut into the tape using a laser.

The third set of specimens does not contain a controlled flaw.

e_-Cx -tunic Tape

Figure 1. Test Unit

397
The test sheets used in this experimentwere made by tape-casting,a specialized ceramic

fabricationtechnique. Tape-castingis used to form sheetsthat have large surface areaswith

verythin crosssections. These ceramicsheetsare essentiallytwo dimensionalin nature and

are used as the basicbuildingblocksfor many electronic substratesand packages. Green

ceramictape has also beenused asthe feed materialfor a rapid prototypingprocess called

laminatedobject manufacturing(1). Lone Peak Engineeringoriginallydeveloped thistest

apparatusto rate the suitabilityof different ceramic tape compositionsfor use in an

automatedlaminationsystem.

Equipment and Supplies

1. Table-top test unit (see figuresfor details)

2. Green ceramic tape

3. Access to a scale

4. Data sheets

5. Calculator or computerized spreadsheet

Procedure

The professor should review how the test apparatus works with the students. The test

apparatus is detailed in Figure 2. Overalloperation of the test unit isfairly simple.

F'_ure 2. Det_ed Test Unit

398
Ste

(1) Make tape measurements (subtract mylar backing thickness from total),

(2) Record information on data sheet,

(3) Remove tape from mylar backing,

(4) Insert tape into plastic sleeve,

(5) Place clamp over sleeve ( clamp has nylon cable with hook attached),

(6) Attach empty load container to hook,

(7) Attach free end of tape to the lever clamp (clamp, nylon cable, hook, and load

container should be attached to the other end of tape specimen before attaching to

lever clamp),

(8) Tare weight container,

(9) Pour weights into load container at a steady rate until tape fails,

(10) After failure, pour weights from load container into weight container, and

(11) Weigh and record data.

Data Sheet

The student should use a separate data sheet for each specimen set. A sample data sheet is

presented as Figure 3. It isrecommended that students work in pairs and that 5 samples from

each set be tested.

.DATA SECTION

.._m_l_ Cornpon'ition:

[ NUMe_ s_.._ [ OESC_J_rToN v,.Aw [ _GRA_S) LOAO [

T

2

3

5"

OB..q.ERVATION -q;'-CTION

_Figure3. Sample Dam Sheet

399
Have the students calculate the standard deviationfor each set of sheets using the formula

below.

,/_-,)

s = y _(xrl::)2/_-1)

Where:

N = the total number of specimens measured

I_ = the failure load of each individualspecimen

F = the average failure load

Test SpecimenDetails

The test specimens have the following dimension.

(1) Width = 3.8 cm

(2) Length = 7.6 cm

(3) Flaw length (2a) where (a) is either 0, 0.48, or 0.95 cm

Stress

!.

.2a _Y Length

i Width

Figure 4. CeramicTest Specimen

400
Instructor's Notes

The instructor should have the student's examine the failure area. Perhaps a drawing, such as

presented below, would be helpful. The specimen in Figure 5 broke uniformly. The students

should writeup a report to go with the data sheet that summarizes their findings. It would be

helpful if the instructor covered some design theory as it relates to flaws in materi_Is before

the students begin the experiment.

Figure 5. Failure of a Flawed Test Specimen.

References

1. _ C.W., Daufenbach, $., and Feygin, M., flexibleManufacturing of Advanced

Structural CeramicsUsing Laminated Object Manufacturing Techniques, Phase I

DARPA, Arlington,Vkginia under Contract DAAHO1-92-C-R244, DAAHO1-93-C-K350,

1993.

Source of Supplies

It would be possible to make your own table-top tester using the details provided by the

different drawings. Green ceramic tape can be purchased from commercial vendors or

prepared by students in a University laboratory setting. However, LPE has prepared this

experiment as a complete kit. The kit includes:

1. Table-top tester

2. Supply of ceramic tape, with and without controlled flaws.

3. Data sheets

Please contact Lone Peak for additionalinformation.

401

STUDYING MACROSCOPIC YIELDING IN

WELDED ALUMINUM JOINTS

USING PHOTOSTRESS

Kishen Kavikondala

Department of Engineering Science and Mechanics

University of Alabama

Tuscaloosa, Alabama 35487

Telephone 713-586-7775

and

S. C. Gambrell, Jr.

Professor of Engineering Mechanics

University of Alabama

Tuscaloosa, Alabama 35487

403
STUDYING MACROSCOPIC YIELDING IN WELDED ALUMINUM

JOINTS USING PHOTOSTRESS

Kishen Kavikondala S.C. Gambrell,Jr.

Dept. of Engineeringscience & Mechanics Professorof Engineering

University of Alabama Universityof Alabama

Tuscaloosa,Alabama 35487 Tuscaloosa,Alabama 35487

Key Words: Photostress, Photoelastic Coatings, Stress Analysis,

Material Characterization, and Mechanical Behavior.

Prerequisite Knowledge: Senior in College having a basic

understanding of mechanics of materials and mechanical behavior of

materials. The instructor should give the student a basic lecture in

the theory of Photoelasticity and its application to strain

measurement.

Objective: To observe the macroscopic yielding characteristics of a

welded aluminum joint using photoelastic coatings. To determine the

variation in the stress-strain behavior on a point by point basis in

the weld metal and the heat affected zone.

Equipment:

i. GTAW aluminum plate (2219-T87 base plate and 2319 filler)(or

appropriate substitute).

2. Rubbing alcohol (or acetone).

3. Coarse and fine silicon-carbide paper (220 grit and 400 grit).

4. Gauze sponges.

5. Q-tips.

6. Flat wooden mixers.

7. Metal surface cleaner (M-prep conditioner A).

8. Neutralizer (M-prep neutralizer 5A).

404
9. Photoelastic Coating (PS-I).

i0. Adhesive (PC-8).

ii. Reflection polariscope with a uniform field compensator,

tele-microscope, and a digital strain recorder.

12. Universal Testing Machine.

13. i000 speed color film.

14. Automatic camera.

15. Curve fitting program on a computer.

Introduction: Many structures are fabricated by welding standard

structural members such as beams, columns, angles, etc. The process

of welding involves melting, phase change, and intimate inter-granular

mixing of the two metals to be joined. Heating and cooling during

welding is known to alter the mechanical properties of the weld metal

and the metal surrounding the weld, called the heat affected zone

(HAZ).

Characterization of yielding behavior in weld material and the

surrounding HAZ is very important for a complete understanding of the

response of welded joints to loads. Knowledge of the mechanical

properties and the macroscopic yielding characteristics is very

important for accurate modeling and design of structures having welded

joints.

There are several experimental methods which canbe used to determine

the distribution of strain in structures and other machine components.

The most common method is the use of electrical resistance strain

gages. Unfortunately, strain gages provide data only at points where

they are mounted on the structure and little is learned of the

yielding characteristics of other regions. The method of

Photostress, also known as the method of photoelastic coatings, is a

full field optical technique which allows the study of macroscopic

yield behavior in the area of interest. At the same time, it allows

for measurement of strain on a point by point basis. A detailed

description of the theory of photoelastic coatings can be found in [i].

The Photostress technique allows for measurement of maximum in-plane

shearing strain using the equation:

7 = _i - €2 = Nfc

405
where f_ - I/2TK and

7 is the maximum in-plane shearing strain,

_I and _2 are the principal strains,

N is the fringe order,

f_ is the fringe value,

is the wavelength of light = 22.7 x 10-6 in,

K is the calibration constant of the coating, and

T is the thickness of the coating used (0.01 or 0.02 in.).

Procedure:

Specimen Preparation: Machine a dog bone specimen (Figure i) from

welded aluminum plate based upon the capacity of the testing machine

and the ultimate strength of the material. Insure that the centerline

of the weld is at the center of the specimen. Using the coarse

silicon-carbide paper, abrade the area of interest which is the weld

metal and the area surrounding the weld metal (approximately 2 inches

on either side of the weld centerline). Clean the abraded area with

rubbing alcohol (or acetone) and gauze sponges to remove foreign

substances. Put a few drops of metal surface cleaner (diluted acid)

on the surface and wet-lap it with fine silicon-carbide paper. Clean

the surface with a gauze sponge, add a sufficient quantity of

neutralizer (diluted basic solution) and, using a Q-tip, clean the

surface thoroughly. Before th_ surface dries, wipe it clean with a

gauze sponge.

Cut the photoelastic coating (PS-I) to the required dimensions (see

Figure i) using sharp scissors. Care should be taken not to snap the

scissors as this results in damage to the coating material. Using a

flat wooden mixer, spread the adhesive (prepared by your instructor)

evenly on the surface of the specimen. Place the cut photoelastic

coating sheet along one edge of the specimen and slowly press it into

position while working out the air bubbles in the process (see Photo

i). After approximately 45 minutes, make a fillet of the adhesive

along the edges and remove the excess adhesive. Let the specimen cure

at room temperature for 48 hours. Then take the specimen and, using a

permanent ink marker (Figure i), mark the locations where you want to

measure strain. Now the specimen is ready for testing.

Testing:

Based on the capacity of the testing machine, prepare a loading

sequence to load the specimen in a reasonable number of steps to about

90% of the ultimate strength of the weld metal. Using Photograph 2 as

a reference, set up the experiment. Program the universal testing

4O6
machine to load in the predetermined loading sequence. Have the

camera loaded and focused to photograph the fringe patterns. After

the experiment set up has been completed, turn down the lights in the

lab. Adjust the direction of the polariscope light source to see that

there is no reflection off of the coating material and that the light

shines uniformly on the photoelastic coating. Start loading the test

specimen and, at each load step, take a photograph of the fringe

pattern and, using the telemicroscope attached to the reflection

polariscope, measure the strain as explained by your instructor in the

introductory lecture. Tabulate load and strain (micro strain)

measured at each point as shown in the sample below:

Measured ShearinqStrain

Load Centerline Quarter- Half- Three-quarter One-inch

(lbs) point point point point

2000 800 600 450 200 190

4000 ll00 880 630 280 250

Photograph 2 shows the progressive development of fringe patterns for

a 1.4" thick, 2219-T87 welded aluminum joint and the corresponding

stress values. It can be clearly seen that the fringe development

gives a good representation of the yielding characteristics of the

weld metal and the surrounding heat affected zone. This understanding

is critical in developing analytical and finite element models for

welded joints.

After measuring the strain, convert the load values into the

corresponding stress values based upon the cross-sectional area of the

specimen and, using a curve fitting program, plot stress-strain curves

for each of the points. Figure 2 shows stress-strain curves for the

1.4" thick welded aluminum joint shown in Photograph 2. The stressstrain curves show the highly non-linear behavior of the welded joint

and the variation in mechanical properties from the center of the weld

outward to points one inch away. This technique can be used not only

on flat surfaces but can also be used on curved surfaces if the

photoelastic coating is contoured to the shape of the surface while it

is in a semi-polymerized state.

Notes to Instructor:

All materials and techniques required for using Photostress can be

obtained from Measurements Group, P. O. Box 27777, Raleigh, North

Carolina 27611. Telephone (919)365-3800. They also can provide a

wide variety of literature on using photoelastic coatings. A few of

407
their bulletins are listed in the reference section. They will be

particularly useful in conducting the experiment described.

References:

i. Coker, E. G., and Filon, L. N., 1931, "A Treatise on

Photoelasticity," Cambridge University Press.

2. "How to Select Photoelastic Coatings," Measurements Group, Inc.,

Literature, Raleigh, NC, TN-704, (1978).

3. "Photostress Instrumentation," Measurements Group, Inc.,

Literature, Raleigh, NC, Bulletin 315-B, (1989).

4. "Automatic Data Acquisition," ADA-I through ADA-8, Measurements

Group, Inc., Literature, Raleigh, NC.

5. "Operating Instructions and Technical Manual-Strain Measurement

with 030-Series Reflection Polariscope," Measurements Group,

Inc., Literature, Raleigh, NC.

6. "Instructions for Bonding Flat and Contoured Photoelastic Sheets

to Test-Part Surfaces," Measurements Group, Inc., Literature,

Raleigh, NC, IB-223-F, (1982).

7. "Instructions for Using PC-8 Adhesive," Measurements Group, Inc.,

Literature, Raleigh, NC, IB-231, (1982).

408
Photo 1. Typical Spechn Figure 1. Sketch of Specimen 
(a) 25,260 psi (b) 28,890 psi (c) 36,100 psi 

Photograph 2. Shear Strain, Through Weld, Bead On 
Photostress - Strain curves 

'l'l~rougli weld , Vertical Centerline 

5 1000 

S/~ecinzerts 2-3,3-4 & 3-5 

0.71" * 1.4" , Weld olt 

Cetzterlirze 

One fourtlt i~zclline 

---. One halfi~tclline 

--. Three four.tlts inch line 

--- One irzclt line 

! 

0 

0 4000 8000 12000 16000 20000 

Shear Strain * 10E06 

Figure 2. Behavior, Weld On, Vertical Ce~lterlille 

BUBBLE RAFTS, CRYSTAL STRUCTURES,

AND COMPUTER ANIMATION

James V. Masi

Department of Electrical Engineering

Western New England College

Springfield, Massachusetts 01119

Telephone 413-782-1344

413
414
BUBBLERAFTS, CRYSTAL STRUCTURES,

AND COMPUTERANIMATION

James V. Masi, Ph.D.

WesternNew England College

Dept. of ElectricalEngineering

Springfield, MA01119

(413) 782-1344, FAX(413) 782-!746

KEY WORDS: Crystals, bubble rafts, computer animation, which do nol show any long-range order and only have

directional bonding between atoms. The simplest crystal

PREREQUISITE KNOWLEDGE: The student should be structures are composed of pure elements and exhibit isotropic

familiar with the basics of materials science and chemistry, properties due to non-directional interatomic bonds. These

Levels at which these experiments are performed are second aloms pack togelher in such a way as to minimize the open

semester junior and either semester senior year. The students space in the structure and form what we call close-packed

are first given lectures on crystal structures, solids, and basics of crystal structures. There are fot,rteen ways in which atoms can

crystallography, defects, and diffraction. No microscopy is arrange t 1eraseyes in space. These are called the Bravais

needed and only a computer and an overhead projector are Lattices, shown in Figure I below. Looking at these, one can

really essential. A video filmed by the instructor showing the

_ubble formation and the computer animation gives the student

an idea of what is expected.

OBJECTIVES: To illustrate the process atom-by-atom ,.

structureforthation usingbubbleraftsandto show __ 'a,. _"'--_'[ _.._, _/__x ,V /'I

three-dimensionalanimatedstick,bail, andhard-sphere /_-_ _----_ ]'i*_-'*_--_' , t ', / "

animated computer models using public domain software on one , . _ ....

360K floppy. This should aid the sometimes filtile attempt by ,\._/

boththe professor to teach and the student to visualize crystal S_p,_ E,,d....... d

structures and defects, monoclinic m,mr_clinic Triclinlc Hexagonal Rhombohedral

EQUIPMENT AND SUPPLIES:

tI) Pyrex flat, square dishes ( 2 per student)

(2) Oleie acid, triethanolamine, glycerine, miscellaneous s;°,p,o _ody........._ E.d........d v...........

chemicals, orthorhombic orthofhombie orthorhombic orihorhombic

(4) A pin,

{5) A 286/386/486 PC with DOS or Windows,

(6) Public domain software (ptnvided).

Simple Body-centered

INTRODUCTION: Using simple chemicals and materials and ,_,,._o._t ,_,,.go.._

using simple, public domain software, tile student can become

betler acquainted with crystal structures, defects, and stacking in

two andthreedimensions.Crystalsymmetryandthe densityof _ ._i _

atomic packing using the hard sphere model can be easily

visualized. Rotation of the specimens in three dimensions and

creation of varying types of defects can be easily accomplished " F.=-_.,_,_ Simple Body-cx:ntered in this one session laboratory, c,,b_ _.b_ _.b;_

Part l:Crystal Slructures: Crystalline materials tend Fi!_ure !

to have long-range order in the position and stacking sequence The fourteen Bravais Lattices

of atoms or molecules. On the other hand are amorphous solids,

415
observe that they have different rotational symmetries, Miller

indices of their planes, holes. ,andpacking densities. By

examining models of these crystal structures, one can become

more familiar with their physical properties and bonding

relationships. Numerous references give excellent introductions

to crystallography_'_'_.

Part lh Imperfections: In today's world, we know

there is no such thing as a perfect crystal, so we can visualize a

real crystal as the superposition of discrete imperfections onto a

perfect crystalline lattice. These imperfections may be

conveniently classified with respect to their dimensionality 2

Zero dimensional imperfections are known as point defects.

Point defects are located at defective regions of a crystal that are

confined to a volume of a point (a sphere of atomic dimensions).

Some ex,'unplesof this cl_s are vacant lattice sites and impurity

or foreign atoms. Ex,'unplesof these types of imperfections are

shown in Figure 2.

Figure 3

Grain boundary

arrangement of atoms of a crystal is interrupted. The

._ _ __ three-dilnensio,lal c,.qs._ or de|'ects are knowTl as bu,k defects.

( _ ' Bulk defects are macroscopic defects that represent an

inhomogeneity on the shape or stn]cture of a solid. Some

typical bulk defects are voids and cracks. Two of these are

shown in Figure 4.

(a) (hi (c)

_l_nnklll_o ¢lvitils in I _tl_i elltln O.

Id) (€1

',_:_', ..:il!

Figure 2 .k

Classifications of point defects _:'.: -.'_'..

(a) vacancy; (b) divacancy; (c) ion pair vacancy (Schottky :_.,-_ , .f'

defect); (d) interstitialcy; ,.'_i-:"i_:

and (e) displaced ion (Frenkel defect) :_,_r.i

The one dimensional class of imperfections ,areknown as line -'_.':_'

imperfections, or, generally called, dislocations. There are

defective regions of the crystal that extend through the crystal

along a line. This line is not necessarily straight, and it may be _,_,_,, ............. , ,,,.,

curved or even be a loop. Interfaces are two dimensional Figure 4

imperfections that serve as boundaries between regions of a Bulk defects

crystal which have different ordering or arrangements. A These classifications of dimensionality range in size

depiction of a grain boundary is shown in Figure 3. An from microscopic (t0-_'ml to the macroscopic range of fractions

interface is the transition region in which the configurational of meters. A depiction ofthese is shown in Figure5

416
TIlE EXPERIMENTS:

Computer generated crystal struclures:

In order to provide the student with another tool for

visualizing the three dimensional structures in space, a computer

visualization progr,'un called "Chemview" was employed. It is a

public domain, DOS based program costing $3.50 from Sector

I_menstoa (meters) It

I' 4, t0 -,o !'" 'I "z 111 Systems Company, Inc., Marblehead, MA. One can construct as

I 1° I I I complex an organic, polymeric, or crystalline structure as time

permits. This figure can then be rotated in 3-D space and

r r l L"'_' ''''c'' "/ L"b"'k''r'''' d

,- q v q.......... viewed at any angle. If one wishes to incorporate Ibis constlMct

L, Inllrflctal defecll .l

r m into a report, a screen grab may be used or the view (nay be

777 elba:Ironic _lomi¢

•,,_,,,,,,,,h, p.,., _,,,,, printed directly fon'n the program One such construct, a

b,,a.,r, p,, d,f,,,, a,r,,u dodecahedron, is shown (as grabbed frovn tile screen) iv]Figure

(PIIILOSOPI]y) (PHYSICS) (MILITA R_z') "

7. Usually, the studentwill takethe copy of the program from

the laboratory and spend hours making cutaways of planes in

crystal structures as well as challenging variations of diamond

Figure 5 cubic for binary, ternary, or higher compounds. The instructor

Size classification of defects in solids is free to use the program as he or she sees fit. in accord with

classroom or other laboratory exercises. Other more expensive

In addition, some defects may be removed (or moved) by programs _may be substituted tbr this if funding permits.

annealing, making larger regions of perfection in the crystal, as Motivationally, this departure from. 2-D drawings and

shown in Figure 6. Stvrot'oam models is superior for retention ,'rodcrealivity.

./¢

I- P _.:---. _f--l:/.' _ :::_. _::::.:_"%";:_',-_.;:1

%

Figure 7

...... __ Computer generated dodecahedron structure rotated about

__?,_;L an axis

The Imbble raft: The bubble raft is an experiment

originally designed and built by Bragg and Nye' in 1947 to

overcome the student's apparent inability to visualize detect

structures in hard-sphere model solids. In this experiment.

Figure 6 crystal structure of a metal is represented by an assemblage of

Annealing to enlarge regions of crystallinity millimeter-sized bubbles, Iloating on the surface of a soap

(depictions (a) through (d) showing annealing vs time) solution. The bubbles are blown beneath the surface of the

417
solution under constant air pressure, creating a highly uniform

,arrayof bubbles (atoms) held togetherby capillary attraction,

simulating quasi-flee electron forces. This experiment shows

representationsof structuresin two and threedimensions, such

as point defects, grain boundaries5,faults, slip, recrystallization.

annealing, and strain, all at room temperature. These structures

can he easily observedon ,anoverheadprojector.

1) To 15.2 cc of oleic acid,

2) Add 50 cc distilled H20.

3) Mix (shake well) together.

4) Mix with 73 cc of 10% solution of _...... o._.....

triethanolamine and the mixture made up to 200 cc.

5")Add 164cc pure glycerine.

6) Let stand and draw of clear liquid from below.

(Jrnhl t,q,.idari_'_

7")This solution can be diluted in three times its volume

of water to reduce its viscosity.

8) From this decant, yield is approximately 300 mE,of

usable mix.

9) Dilute with 150 mL of H_Oto make soap solution Figure 8(b)

for trays. Observations of defect structure using bubble rafts

10")Tomake solution: 1:4 bubble solution to water. Reporting: On the photographstakenor on a suitable

Using an eyedropper as a nozzle held at least 0.5 cm drawing,indicate the positions of tile following: (a) a vacancy;

_elow the surfaceof the solution, blow the bubbles using an (b) a grain boundary;(c) a triple point:(d) a dislocation; (e) an

aspiratorbottle, making sure that the bubbles format a slow and impurity atom. Following your observations of the bubble raft

unitbrm rate. Bubbles should be of the order of 1-3 mm in andof yourstudies of imperfections, you should be able to

diameter. Using an aspirator bottle held at a given level, a sitar,late the tbllowing:

tmiform pressure can be delivered to the bubble nozzle orifice. I) A polycrystalline structure and crystal or grain

In the same tray, these bubbles may be used to simulate grain growth, grain boundaries. How did you do it? What happened?

boundaries, dislocations, vacancies, slip, recrystalization, and 2) Vacancies and impurities. How did you do it? What

annealing By introducing smaller or larger bubbles, impurity happened?

atoms may be simulated. By putting a piece of fiat wood into 3) Dislocations showing their motion (apply a stress to

one side of the solution, simulation of stress c,'mbe achieved, the raft), their interaction, mutual annihilation, and climb of

The meeting of two dislocations results in an observed vacancy dislocations. Ple:tseindicate graphically and narratively what

formation as well. Typical examples of the bubble simulations happens.

are shown in Figures 8(a) and 8(b). Using tile computer modeling programs, construct a

structure of your choosing. This should be of at least the

difficulty level of a face centered cubic structure.

Alternate scenarios of diffusion (using dyes), climb

(propagating a defect), and putting large and small bubbles on

opposite sides of the tray (solid solution formation) are possible

with some practice. Once again, making the bubble material

.-:., available to the student, even after the laboratory sessions,

allows for a safe and realistic simulation of defects.

Summary: Using simple chemicals and materials,

students can familiarize themselves with the basics of crystal

/. _ structures, defects, and three-dimensional computer models. A

fidl experiment is provided for implementation of this

laboratory. By employing inexpensive, public domain, computer

ot,l_q,u,.1,-orth,,.._l.... io,,l_r,. programs, meaningful visualization and retention of three

dimensional structures are possible.

These experiments were developed by seniors in the

process of their senior desigll project capstone courses at

Figure 8(a) Western New England College.

418
REFERENCES:

1. VanVlack,L. H., Elementsof MaterialsScienceand

Engineering,6thEd., Addison-WeslePyublishingCompany,

ReadingM, A 1989.

2.Jacobs,J. A. andKilduff,T. F.,EngineeringMaterials

Technology,2ndEd.,PrenticeHallPublishingCo.,West

Nyack,NY 1994.

3. ShackelfordJ., andAlexander,W.,The CRCMaterials

ScienceandEngineeringHandbook,CRCPress,BocaRaton,

FL 1991.

4. Bragg,L. andNye, J.F.,A dynamicalmodelof a crystal

structure, Proc.of the RoyalSoc.of London, A190, 10.1947.

5. Ishida,Y., Bubbleraft grain boundaries,in Order

Structures,ChapmanHall, 1972. pp.75-82.

6.Chemintosh,AutodeskModules,Chemwindows,etc.

SOURCESOFSUPPLY: The laboratorysuppliesand

chemicalswere obtainedfromCole-Parmerand Fisher

Scientific. Allothersuppliesare easilyobtainedfromlocal

universitysupplyhouses. The softwareis publicdomainand is

availablefromSectorSystemsSoftware,Marblehead,MA.

419

IN-CLASS EXPERIMENTS: PIANO WIRE

AND POLYMERS

David Stienstra

Department of Mechanical Engineering

Rose-Hulman Institute of Technology

5500 Wabash Avenue

Terre Haute, Indiana 47803

Telephone 812-877-8422

421
In-Class Experiments: Piano Wire and Polymers

David Stienstra

Assistant Professor of Mechanical Engineering

Rose-Hulman Institute of Technology

Terre Haute, Indiana

Overview

A number of challenges arise when teaching an introductory materials engineering course.

Many students lack hands-on experience with hardware, especially with the variety of

currently available materials. Laboratory experience is an effective way to deal with this

challenge, but the available time, money, and facilities often constrains the amount of

laboratory exposure. One solution that allows students to explore material response in less

time and a lower cost is to have small in-class experiments.

In the introductorymaterialscourseatRose-HulmanInstituteofTechnology,a numberof

smallexperimentshavebeenusedto getthe studentsactivelyinvolvedwithmaterialsin the

classroom. Theseareteam-basedexperimentsin whichthe studentsexplorematerialresponse

and attemptto relatematerialbehaviortomaterialprocessingand microstructure.

Two short, inexpensiv.e in-class experiments are described in this paper. In Part One students

experimentwith music wire to reinforce their understanding of processing, microstructure and

properties of steel. In Part Two, some readily available polymer parts and toys are used to

discuss viscoelasticity, and polymer microstructure.

Key Words:

Part 1: Cold Work, Heat Treatment, Steel

Part 2: Polymers, Viscoelasticity,

Prerequisite Knowledge:

Part 1: Some knowledge of the processing-microstructure-property relationship for

steel.

Part 2: Difference between thermosets and thermoplastics, microstructure of polymers,

deformation mechanisms of polymers.

Objective:

1)to help the students develop an intuitive understanding of materials by hands-on

exposure to material behavior and correlation with processing and microstructure.

2) to continue to encourage cooperative learning 1through the use of a team-based

problem solution. The goals for the individual experiments are listed in the class

handouts.

422
Part One: Music Wire

The following are abbreviated versions of the course handouts used for the music wire

experiment. To encourage teamwork, one handout is given per group.

Properties of Music Wire

Task: To qualitatively examine the mechanical properties of three pieces of music wire

and deduce the processing that produced those mechanical properties. Justify your

deductions from a microstructural perspective using the information and tools

learned in class.

Materials:Three 10-15 cm long samples of 20 Gauge (0.045 in diam.) steel music wire. Each

sample has been processed differently.

• Specimen A - Shiny.

• Specimen B - Not shiny, blue dye on one end.

• Specimen C - Not shiny, no dye at either end.

Group member roles: For this work identify a recorder and a runner for your team. Their

responsibilities are:

Recorder - Record all group observations on the supplied sheet.

Runner - Act when needed according to the following instructions.

Instructions:

1. Have runner acquire one of each type of specimen for the group from the table at the

front of the room.

2. Each person in the group will try to bend each specimen

3. As a group, discussthe mechanical behavior for each specimen and record your

description.

4. As a group, deduce and justify:

• What type of microstructure each specimen has

• What type of processing each specimen has seen.

Background:

Music wire is a high purity plain carbon steel with carbon content of approximately

0.8%. It is sold in the cold worked condition (formed by wire drawing). The strength

in the cold worked condition is typically between 200 and 400 ksi. As purchased, it

should be able to bend back on itself (180° bend) without fracture. The primary

industrial application of music wire is for springs.

423
Properties of Music Wire

Recorder Sheet

3. Description of the mechanical properties (qualitative) of the specimens.

• Specimen A

• Specimen B

• Specimen C

.

Specimen Microstructure Justification

A

B

C

Specimen Processing Justification

A

B

C

Instructor Notes: In the piano wire experiment, each team of three to four students receives a

packet of three color-coded short lengths of piano wire that have undergone different thermomechanical treatments. The students are instructed to bend each of the wires, noting the

relative force required for each and comparing the materials with respect to strength and

ductility. After testing, each student team must answer a series of questions that require them

to deduce the processing and consequent microstructure of the steel. All deductions must be

accompanied by reasoned justification.

• Specimen A was the music wire in the as-received conditioned - cold worked to high

strength.

• Specimen B was heated to 1600°F for one hour and quenched in water.

• Specimen C was heated to 1600°F for one hour and furnace cooled.

• As an alternative, a specimen D that has been austenitized, quenched, and tempered

could be included, but tends to create significant confusion_

At the time of the experiment, the students had received a thorough grounding through lecture

in cold work and annealing, and had an introduction to steel microstructure and heat treating.

Consequently, the student's could be expected to recognize that the very brittle response of

Specimen B was due to a martensitic microstructure caused by being austenitized and

quenched. Likewise, the shiny appearance of Specimen A indicated no thermal processing

and its strength and ductility was good evidence that the material is still in the as-received

424
condition. The very soft and ductile Specimen Cpresented the students with the most

difficulty. Ninety percent of the twenty groups correctly identified the microstructures of

Specimen A as pearlite and Specimen B as martensite. For Specimen C, one third of the

teams correctly deduced pearlite. Of the others, one third deduced bainite and one third other

responses.

The small group discussion in this exercise allows two important things to take place. First,

the students must convince each other that their answer is correct. This encourages them to

apply reasoning rather than memorization to solve the problem. Second, discussion provides

an opportunity for the students to sort out the meanings of the new vocabulary. Past

experience indicated that many students were confused by the quantity of new vocabulary

describing the microstructure and heat treatment of steel.

The results of the lab indicated several things. The fact that many of the students expressed

surprise at the differences in mechanical behavior showed the lack of experience with

materials. Observation of the teams showed that the cooperative effor_of the group was

helpful in reaching the correct responses. The groups making the mistakes were often

guessing and were not able to relate the book values for hardness of the microstructures to the

relative strengths of the wires.

This experiment could be done at the outset of introduction to steels as well, but less could be

expected of the students in terms of microstructure and processing.

Part Two: Polymers

The following are abbreviated handouts used for the polymer experiment.

Time Dependent Properties of Polymers

Task: To qualitatively examine the effect of strain rate on the mechanical properties of

several thermoplastic polymers and relate those properties to microstructural

behavior.

Materials: Three polymer samples.

• Silly Putty

• Six Pack Rings

• Nylon cable tie

• Splat Ball

Group member roles: For this work identify a recorder and a runner for your team. Their

responsibilities are:

Recorder - Record all group observations on the supplied sheet.

Runner - Act when needed according to the following instructions.

425
Instructions:

1. Have runneracquire one of each type of specimen for the group.

2. Silly Putty

• Each personshoulddeterminethe effect of strain rate on the mechanicalbehavior

of silly puttyby pulling slowly, pullingquickly, and throwingdown on the floor.

• As a groupdescribe(and record)the behaviorin engineeringterms.

3. Six PackRings

• Eachpersonshouldpull one loop of thetings very slowly and pull one loop of the

tings very rapidlyto failure.

• As a group,describe (and record)the mechanicalbehaviorusing engineering

terms.

4. Nylon cable ties.

• Each person should pull one cable tie loop very slowly and pull one cable tie loop

very rapidly to failure.

• As a group, describe (and record) mechanical behavior using engineering terms.

5. Splat balls.

• Each person should throw the Splat ball on the table top.

• As a group, describe (and record) mechanical behavior using engineering terms.

5. As a group, Deduce and Justify:

• What happens in the microstructure to produce the behavior in each case. (Are the

materials thermoplastics or thermosets?, What are the molecules doing?)

• What type of polymer would be a good choice for six pack rings. (what are the

important criteria and how does your choice meet those criteria?)

Recorder Sheet

1. Description of the mechanical properties (qualitative) of the specimens with emphasis

on the effect of strain rate"

• Six Pack Rings

• Silly Putty

• Nylon Cable Ties

• Splat Ball

2. Deductions regarding microstructure

Specimen Microstructure Justification

Six Pack Ring

Silly Putty

Cable Ties

Splat Ball

3. Materialselection for six pack rings(and why?).

426
Instructor Notes:

The students really enjoy throwing the Splat balls and silly putty. Consequently, the learning

process can quickly degenerate into pure fun without some gentle external pressure and a time

deadline.

At the time of this experiment, the students have had lectures on the difference between

thermoplastic and thermosetting polymers. As part of this they have heard about the

microstructure, deformation mechanisms and the consequent time- and temperature-dependent

behavior (viscoelasticity). This experiment allowsthe students to experience extremes of

polymer response with parts that they recognize and can manipulate.

Silly Putty is a time-honored demonstrator of the coupling of large scale viscous response

(creep) under slow strain rates and highly elastic response (and "brittle" fracture) under faster

rates. The student's task is to recognize that the elastic response results from the "entropy

spring" of chain coiling and uncoiling with relatively little internal friction, while the viscous

response results from relative chain sliding.3

The polyethylene six pack rings are also show the effect of strain rate clearly with significant

drawing behavior at slow strain rates and little deformation at high strain rates.3 Note that

many of the newer six pack rings are designed with notches to reduce animal strangulation,

and will not draw as expected. The increased opacity of the stretched portion of the rings

allows the instructor to discuss crystallinity. The use of a heat gun to reverse the process can

reinforce the concept of the aligned, crystallized neck reverting to a less aligned and more

amorphous original state.

The nylon cable ties reinforce the notion that viscoelasticity of the stronger engineering alloys

operating below their glass transition temperature may present more subtly and the effect may

be missed in casual examination.4 If the cable ties have about the same cross-sectional area as

the six pack rings, the difference in tensile strength between a low density polyethylene and

nylon is also apparent.

Splat toys flatten significantly when thrown against a surface and then slowly recover to

original shape. They are included because of their ability to fully recover after large scale

deformation. These are available at K-Mart as Splat Bunnies and Splat Trolls. American

Science and Surplus (3605 Howard Street, Skokie, IL 60076, 708-982-0870) sells them as

Sticky Balls for less than $2 apiece. Again we have an example of a time dependent entropy

spring, but this time in a lightly cross-linked polymer that allows the shape recovery. The

students generally do not make the connection between the large scale recovery of rubber

bands and the recovery of the Splat balls.

In-class discussion following the polymers experiment centered on the design challenges and

the engineering applications of viscoelastic materials. Special emphasis was placed on design

for creep and applications of energy damping.

427
Conclusions:

Spendingclass time in this way was valuable for several reasons. Student evaluations

indicated that the majority of the students found the in-class, hands-on work very helpful and

recommended that use of such labs be increased in the future. Some students still resisted

working in teams, but many also found that aspect helpful. In particular, by observing the

groups at work, I was able to see more clearly holes in the student's knowledge, and the

problems students were having integrating that knowledge. Finally, the equipment used is

relatively inexpensive and easily available.

References:

1. Johnson, D.W., Johnson, R.T., Smith,K, A., Active Learning: Cooperation in the

Classroom, Interaction Book Company, Edina, MN, 612-831-9500.

2. Newey, C. and Weaver, G., eds.: Materials Principles and Practice, Butterworths, London,

1990,pp. 310-311.

3. Ibid, pp. 314-316.

4. Weidman, G., Lewis, P., and Reid, N., eds.: Structural Materials, Butterworths, London,

1990, pp. 220-224..

428
DIELECTRIC ANALYSIS FOR

POLYMER PROCESSING

Kris Kern

and

Heidi R. Ries

Materials Research Laboratory

Norfolk State University

2401 Corprew Avenue

Norfolk, Virginia 23504

Telephone 804-683-2447/8020

429
430
DIELECTRIC ANALYSIS FOR POLYMER PROCESSING

Kristen T. Kern and Heidi R. Ries

Center for Materials Research

Norfolk State University

Norfolk, Virginia

Edward R. Long, Jr.

National Aeronautics and Space Administration

Langley Research Center

Hampton, Virginia

ABSTRACT

The cure cycle for an epoxy resin is investigated using a system for monitoring

frequency- and temperature-dependent dielectric properties. The dielectric analysis

system is computer controlled and features a comb capacitor small enough to be

imbedded in a sample of material. The system allows for monitoring of dielectric storage

and loss constants for frequencies spanning 5 orders of magnitude, with the temperature

of the sample controlled independently. In addition, the dielectric analysis system may

be used to study cure mechanisms and glass transition temperatures.

KeyWords: cure cycle,dielectricproperties,epoxyresins,polymericmaterials

processing.

Prerequisite Knowledge: General information about polymer structure and synthesis,

basic AC circuit theory, definitions of various dielectric properties.

Experimental Objective: To evaluate the cure state of an epoxy resin for various cure

profiles using dielectric analysis.

Learning Objectives: After completing this experiment, the studentshould be able to

1. describe the dielectric response curve as a function of cure time for an epoxy resin.

2. explain the dielectric response curve very generally in terms of the molecular

changes during the cure cycle.

431
_TRODUCTION

The epoxy resins form an important class of thermosetting polymers with high

adhesive strength, low shrinkage, good chemical resistance, and excellent mechanical and

electrical properties. While many commonly used epoxy resins rapidly crosslink at room

temperature when mixed with a curing agent, others require elevated temperatures for

cure and may be shipped from the manufacturer with the curing agent premixed.

Epoxy resin manufacturers provide data sheets with recommended cure cycles,

typically obtained by evaluating the state of cure by using thermal techniques such as

differential scanning calorimetry (DSC) with small specimens. However, the optimum

cure cycle may vary depending upon the desired degree of cure for a particular

manufacturing application, and may be difficult to determine via thermal techniques due

to the size of the product. While an appropriate cure cycle for the product may be

identified by thermally cycling the epoxy resin and then conducting post-cure mechanical

and electrical tests, this approach may require many attempts before the optimum cure

cycle is determined. Therefore, to optimize the curing process efficiently, it is desirable

to have an in-situ analysis technique capable of identifying the onset and completion of

the crosslinking reactions regardless ofspecimen size.

Electrical measurements have long been used as an alternative to thermal

techniques to estimate the extent of crosslinking [1] in epoxy resins, and the dielectric

properties have been found to be a useful indicator of properties such as viscosity,

density, and index of refraction for materials during chemical reactions [2]. In particular,

measurement of conductivity has been used to monitor the cure processes in

thermosetting polymers.

In the classical experimental arrangement shown in Figure 1, the epoxy resin is

placed in a capacitor (with known empty capacitance Co), an alternating voltage V is

V

Figure 1. Simplified Circuitfor Dielectric Analysis

applied, and the resulting current I is measured. The "resistive" component of the current

IR(that part which is in phase with the voltage and can therefore cause energy dissipation)

432
isgivenby

IR = 0)Co_"V [1]

where cois the frequency of the applied alternating voltage and _" is the dielectric loss

factor [3]. This may be rewritten as:

_"0) = IR/C OV. [2]

The measured current in a polymer has both dipolar and ionic contributions.

Dipolar current is due to the motion of segments of the polymer chain with dipolar charge

distribution when an electric field is applied. The ionic contribution, on the other hand,

results from the migration of charged molecules through the material. The dipolar and

ionic currents vary significantly as a function of temperature and the degree of

crosslinking. However, if isothermal measurements are made the current (and therefore

_"co) will stabilize after an appropriate curing time. The current will, however, vary

somewhat at different frequencies due to differing ability of the chain segments and ions

to respond. Thus the apparent cure time will vary with frequency, and measurements

must be made at a range of frequencies to determine the optimum cure time.

One challenge for this type of analysis has been the ability to perform in situ

measurements during fabrication of components with designs that do not readily accept a

dielectric sensor. This has resulted in the development of the compact, comb capacitor

sensor used in this experiment.

INSTRUMENTATION

A diagramof theexperimentalapparatusis shownin Figure2. Eachcomponent

will be discussedbelow.

Sensor: The sensor used to monitor the dielectric response is a comb capacitor with a

tooth size of 0.02 mm and a tooth spacing of 0.03 mm. The electrode is deposited on a

glass or plastic substrate. The sensor dimensions are 1 in. by 0.5 in. The small size of the

sensor allows it to be imbedded in a small quantity of the material being studied or in a

small section of a large component.

Impedance/Gain-Phase Analyzer: The analyzer applies a voltage to the capacitor and

measures the resulting current and phase information. In particular, the voltage

difference acrossthe sensor and the current through the sensor are measured. The phase

difference between the applied voltage and the current is also determined by the analyzer.

The analyzer repeats these measurements for each frequency specified by the user, and

transmits the results of each measurement to the computer.

433
Thermocouples: A Scanner and DMM/Scanner combination is used to monitor up to 8

thermocouples. Typically one thermocouple is placed on or near the sample to measure

its temperature. Additional thermocouples may be used as desired by the operator.

Computer; All instruments listed above are connected to a computer which is used for

controlling the instruments and data collection. The software for this system is a basiclanguage program written by Dekdyne, Inc. The software features instrumentation

control subroutines which allow for user selection of data acquisition interval, total run

time, aJadAC frequencies for analysis. The frequency range of the analyzer used by the

authors in from 5 Hz to 1 MHz. The system may scan up to 11frequencies during data

acquisition.

Temperature Controller: A programmable temperature controller, independent of the

computer, is used to control oven temperature. This system features a separate

thermocouple for sample temperature measurement.

PROCEDURE

Preparation for measuring dielectric properties requires selection of a cure cycle,

initialization of the dielectric system, and application of the polymer resin onto the

sensor.

Cure Cycle: Cure cycles for polymer resins are provided by the manufacturer, although

the specific application may require modification of the manufacturer's recommendations.

Arrangements for controlling the temperature of the oven must be made. The authors use

a programmable temperature controller which may be programmed priorto the start of

the cure cycle and controls the sample temperature for the duration of the cycle. An

example of a cure cycle used by the authors to cure Fiberite 977-2 resin is shown in Table

1. This cure cycle is based,upon a cure cycle reported by Fiberite Composite Materials

[4], which included a 2 oC/min temperature increase followed by a hold of approximately

38 min at 180 oC.

Table1. CureCycleSelectedfor Fiberite977-2BasedUponReference4.

Step Beginning Ending Duration

Temperature Temperature

1 30 °C 180 °C 71 min

2 180 °C 180 °C 38 min

3 180 °C 30 °C 30 min

434
Initialization: Initialization of the dielectric instrumentation involves entering into the

computer parameters for the cure cycle,such as total time of operation, interval between

data collection, frequencies for analysis, and number of thermocouples. The computer

program then enters a calibration routine, which involves measuring the signal from the

sensor under conditions of having the circuit shorted, having the circuit open, and finally

with the sensor in the circuit but open to air. The program then pauses until the operator

is ready for data acquisition to begin.

Sample Preparation: For sample preparation, the sensor must be brought into contact

with the material to be cured. For liquid epoxy studies, the authors place the sensor at the

bottom of a small reservoir. The uncured epoxy is then prepared for curing as directed by

the manufacturer and poured onto the sensor. As epoxy resins may be quite viscous,

good contact is often not achieved at this point. However, as the sample is heated, it will

become less viscous and willspread over the sensor.

Data acquisition: Once initialization is complete, the temperature controller is started

and the data acquisition routine of the program is started. For the duration of the cure

cycle, the system is automated, and no action by the operator is needed. For analysis, the

system sends an AC signal of known current, voltage, and frequency to the sensor, and

measures the voltage acrossthe sensor, resulting current, and phase difference on the

opposite terminal. From these data, the capacitance and impedance of the capacitor may

be calculated, and, in turn, the dielectric storage and loss constants may be found. These

data are recorded at intervals (typically 60 sec) throughout the cure cycle, and may be

displayed graphically during acquisition orstored and plotted later.

RESULTS AND ANALYSIS

An example of the results is shown in Figure3, where ¢"t.o,(the dielectric loss

constant multiplied by the frequency) of Fiberite 977-2 epoxy resin is plotted as a

function of time during the cure cycle. As the temperature of the resin is raised, _"¢.o

increases, indicating an increase in the in-phase current (see eq. 2). During this stage, the

current in the uncured epoxy is largely ionic, and the increasing _"o3is an indication that

ions are migrating through the material more readily. Furthermore, as the temperature

increases, polymerization reactions are producing additional ions.

At the onset of cure indicated in Figure 3, the crosslinking reactions consume ions

causing the ionic contribution to the current to begin to decrease. These reactions cause

the formation of a molecular network,segments of which may undergo small scale

motion as a result of their dipolar charge distribution. Thus, the dipolar contribution to

the conductivity increases to partially offset the ionic decline as the cure state advances.

Eventually, dipolar contributions become the dominate conduction mechanism.

Presumably, the ionic current contribution will become negligible as the network

435
becomes more complete. Then a value of _"olis reached that is due solely to dipolar

motion. Therefore, the flatness of the _"o_-timecurve after a dwell time at the cure

temperature should indicate the completeness of cure. Dipolar contributions are

dominant as the temperature is lowered at the end of the cure cycle.

EQUIPMENT LIST

The dielectric apparatus as used by the authors and availablefrom Dekdyne has the

following components:

Dielectric Sensors

Schlumberger 1260 Impedance Gain/Phase Analyzer

Keithley199SystemDMM/Scanner

Keithley 705 Scanner

IBM PS/2 Computer

INSTRUCTOR'S NOTES

Equipment: Substitute components may be used. The scanner system used for

thermocouple reading was chosen for the purpose of reading multiple thermocouples.

Single thermocouple readers that may be interfaced with a computer are available. The

major cost of this system is the gain/phase analyzer. Other impedance analyzers are

available from Hewlett Packard amongst other vendors.

Other applications: An inflection in the loss constant curve, indicative of the glass

transition, is characteristic of dipolar current contributions. The system may therefore be

used to measure glass transition temperatures.

REFERENCES

1. Handbook of Epoxy Resins Henry Lee and Kris Neville McGraw-Hill 1967

p.6-13.

2. Epoxy Resins and CompositesIV, Advances in Polymer Science 80mK. Dusek,

ed. ("Dielectric Analysis of Thermoset Cure" S.D. Senturia and N.F. Sheppard,

Jr.) Springer Verlag p.3.

3. Electrical Properties of Polymers A.R. Blythe Cambridge University Press 1979

p. 40.

4. Rheological Behavior of Fiberite 977-2 Resin, Fiberite Composite Materials, Doc

# 77-9.

436
I IBM Cornpatable 

Computer 

HP-IB 

Figure 2. Diagram of AC Dielectric Analysis System. 

ImpedanceIGain-Phase 

Analyzer 

Out ~i~h I v~ow 

Oven 

1 ---------- I 

I Sensor I 

I I 

I 

I 

I Thermocou~le 

DMMI 

Scanner 

In L 

Scanner 

Out In 
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 

Time, min 

Temperature, OC 

Time, min 

Figure 3. Dielectric Response for Fiberite 977-2 Resin. 
CRYSTAL MODELS FOR THE

BEGINNING STUDENT:

AN EXTENSION TO DIAMOND CUBIC

Harvey A. West

Department of Materials Science and Engineering

North Carolina State University

Box 7907

Riddick Hall Room 229

Raleigh, North Carolina 27695-7907

Telephone 919-515-3568

and

F. Xavier Spiegel

Engineering Department

Loyola College

4501 North Charles Street

Baltimore, Maryland 21210-2699

Telephone 410-617-2515

439
440
Crystal Models for the Beginning Student:

An Extension to Diamond Cubic

Harvey A. West andF. XavierSpiegel*

North CarolinaStateUniversity,Raleigh, NC

*LoyolaCollege,Baltimore,MD

Key Words: Crystal,structure,model,diamondcubic

Prerequisite Knowledge: Knowledge of elementary crystal structures.

Objective: Tobuilda modelof thediamondcubicstructureon the sametemplateusedfor

constructionof thebody-centeredcubicstructure.

Equipment:

1. Base template measuring 6" x 6" x 1" made of wood or Micarta with 3/32" holes drilled 1/2"deep

as shown in Figure 1.

2. Stainless steel rods 3/32" in diameter and 6-1/2" in length and inserted into the holes in the base.

3. Wooden spheres(at least 95 tomake eight unit cells) nominally 1"in diameter with 1/8"diametral

holes. These are available from Klinger Educational ProductsCorp., College Point, New York

(Phone 1-800-522-6252). These spheres actually measure 1.025" in diameter which has been

accounted for in the spacing of the rods.

Introducton:

This paper gives an adaptation of the crystal models developed by F.Xavier Spiegel and presented at

the National Educators Workshop: Update '901. The models were originally designed to give

students a better visualizaton of directions, planes, and three-dimensionalrelationships in face centered

cubic (FCC), body centered cubic (BCC), and hexagonal close packed (HCP) crystal structures. With

increased student exposure to the growth and characterizationof semiconductivematerials, a

representation of the diamond cubic structure is also desirable. Simplyenough, a [100]orientationof

this structure can be built on the BCC template.

Construction:

The diamond cubic structure is built upon the same template as givenin Reference 1 for the body

centered cubic structure (Fig. 1) and is based upon the face centered cubic structure with half of the

tetrahedral interstitialsitesf'tlledwith host atoms. The diamond cubic structure is not a unique lattice

441
because, when second neighbor relationships are examined, the environments of all atoms are not

equal. The strucure is treated as an FCC lattice with a basis of two atoms per lattice site, (0, 0, 0) and

(1/4, 1/4, 1/4). The fast plane of atoms (z--0 as shown in Fig. 2) is typical of the (100) plane of FCC

but note that the unit cell has twice the lattice parameter(a) as the BCCunit cell normally constructed

on this template. The second layer (z=a/4 as shown in Fig. 3) has atoms placed in half of the FCC

tetrahedral intersitial sites at unit cell locations (1/4, 1/4, 1/4) and (3/4, 3/4, 1/4). Continuing with the

third layer (z=a/2 as shown in Fig. 4), typifying the midplane of the FCC structure, the atoms are

placed at (1/2, 0, 1/2), (0, 1/2, 1/2), (1/2, 1, 1/2), and (1, 1/2, 1/2). The fourth layer (z=3a/4 as

shown in Fig. 5) puts atoms over the unoccupied tetrahedral sites, namely (1/4, 3/4, 3/4) and (3/4, 1/4,

3/4). The fifth and final layer of the unit cellrepeats the fast layer; however, the comer atoms at (0, 0,

1) and (2, 2, 1) will need support as they will not be in direct contact with any of the previously placed

atoms. This dictates the insertion of spacers constructed from straws, coffee stirrers, or tubing, of

length equal to (a-2r). Using our template based on spheres of diameter 1.025" with a diamond cubic

lattice parameter of 2.368", the spacers should have a length of 1.343" and should be placed over the

rods in the locations denoted in Figure 2. Figures 6 and 7 show the completed model from the top and

side,respectively.

Notes to the Instructor:

The students can be presentedwith such questions as:

What is the packing factor for this structure?

The answeris half of thatfor BCC (0.34) as it has 8 atoms per unit cell (fourtimes as many

as BCC) but occupies eight times the volume.

Why doessuch an open structure result in such a strong,yet brittle, material?

The answer is that this structure is composed of Grou_6IV elements whose electrons prefer

strong, highly directional covalentbonding (hence thefour-fold coorch'nation)as opposed to

metallic bondingwhere the valence electrons are not closely bound to each host atom. The

metallic bond may result in higher coordination,but the atom-atom (ion-ion) bonding is

lower and slip can occur before the overallstructurefails.

This strucure could be built onto an existingBCC structure to give the students an introduction to the

concept of epitaxial growth. In reality, however, BCC carbon does not exist and the substrates which

have successfully been used for the growth of diamond (i.e. silicon and molybdenum) primarily

develop an intermediate layer of carbide.

Reference:

1. Harris, Jonice S. and Jacobs, James A., eds.: National Educators Workshop: Update '90, NIST

Special Publication 822, November 1991, pp. 31-44.

442
• .... r .... • .... ,.... • .... r----I .... 1.... •

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Figure 1. Base layout for the placementof holes for the diamond cubic model

443
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Figure 2. First and fifth layers of atoms (z--Oand z=a). Spacers are used after the fh'st layer.

444
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445
-----'I' I- .... r .... T I

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446
I i l

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447
z=Oandz=a _ z=a/4

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Figure 6. Top view of model

448
z=Oandz= a _ z = a/4

0 z= a/2 Q z= 3a/4

Figure 7. Side view of model with two layers of unit cells

449

TRANSFERRING KNOWLEDGE TO THE

SHOP FLOOR

J. K. Brimacombe

Alcan Chair in Materials Process Engineering

The Centre for Metallurgical Process Engineering

The University of British Columbia

309-6350 Stores Road

Vancouver, B.C. CANADA V6T 1Z4

Telephone 604-822-3667

451
452
_ndish

Mold

"-'_'_ Sprays Shear/torch

:'/". _nch_oU

Figure I A schematicof a billetcaster.

453
Transversemidfacecrack

Longitudinal

midfacecrack Transverse

corner crack

Crazecracks

Diagonal

crack

II Longitudinal

corner crack

III / //Centerline crack

"'-"_'_ = / /Midway cracks I1_

"_11_ Pinchrollcracks

Rhomboidbillet Off-cornerinternalcracks

Figure 2 Schematicofa rhomboidbillet

sbou'ing various O,pesof cracks.

454
_. 80

o

t

i thickness

t

1,200 40

$

'_ Surfacetemperature D

tn

0

amlm

m 600 o

0 5 10 15 20 25

Distance From the Meniscus (m)

Figure 3 AOpicaloutput of themathematicalmodelsbou'ing

predictedsolid sheflthicknessand billetsurfacetemperatureprofiles

(castingspeedof 25 mm per second:section size. 150-mm square).

455
QUALITYPROBLEMSREQUIRING I

DETMLEDANALYSIS

Off-cornerCrack ] _dwayCracks]

TransverseDefects 11r

Rhomboidity I ASCEORI RTAIN GCRA hN CKI

Breakouts _r

SPRAANAL Y YSIS

I MidwayCracks

NO { DOESSPRAYPROBLEM [ '_T-'S

I HighDisbelief UncertainEXI;? HighBelief_

MOLDANALYSIS MOLDANALYSIS MOLDANALYSIS NEEDED

i I I

SPRAYANALYSIS INASPRAPYROBLEM NO

.

I_°_,_s.°_ I

Figure 4 Schemefor diagnosingqualityproblems requiringdetailedmold and/orspray

analysis.

456
ADVERSEMOLD-SHELL [

INTERACTION

I

I I

MENISCUS MENISCUS

I i

t L

CoolingWaterVelocity OilFlowRate NegativeStrip"lime

CoolingWaterQuality OilDistribution MoldLead

Mold-TubeAlignment Oil.PysicalProperties Natureof OscillationMarLs

MoldConstraint OilSystemCleanliness MetalLevelVariation

MoldWallThickness Cleanlinessof MeniscusArea

Positionof MetalLevel CoolingWaterTemperature

MoldCopperAlloy HotFaceTemperature

MoldDesignTolerances

Figure 5 Ageneraloutline of mold-relatedfactors that contritmte to qualityproblems in

billetcasting.

457
KNOWLEDGE

Classes

t Objects Attributes Values Degreeof Belief

I I

I

Keyword Triplets

I"Exclusivesets

Logical | Multichoicesets

t._Fuzz,,s'ets

String

[--Single

Numeric | Double

L..Integer

Rules

_ K_'word Triplet.,;

Condition Statements LogicalConnectives

Predicates/Operators

Functions

_ Ke_-_,ordTriplets

Conclusion Statements _ Ce_'taintFvactors

Else Statements _ Assignments

Functions

Procedures _arch Strategies

_ nference Strategies Input/OutputStrategies

CommunicationControl

Metaknowledge TripleRepresen t tations

_ ustomiz_xQtuestions CustomizedRuleDescriptions

CustomizedExplanations

Figure 6 Knou'ledgeunits availablein theCOMDALE/Xdet_/opmenttool.

458
_ In

Ai _--

/

/

/

l ./

/

/

/ ,

k_

I,_ 5( / "" ....' ................................... tn _ / / OCD-Onlyreheat /

E ] / • / OBD Composition"OR"

_ / superheatproblem

='g ,

mCD,- OAD- Composition",_ND" n-

,_ ._ superheatproblem

o 50 1oo

Belief in High Reheat Due to the

sprays1%1

Figure 7 A schematic illustratingthe calculationof degreeof belief

in a spray-relatedtensilestrainproblemfrom beliefin highreheatin the

radiationzone, highsuperheatand compositionproblems.

459
.E 100 : C

E

/

i ,

/

/

!lb, 50 / /

Bi /

_ OBC- Nomold problem

t OAC- Moldproblem --"E I' "

o 50 1oo

Initial Belief in Spray-Related

Strain Problem (%)

Figure 8 A schematic illustratingthe calculationoffinal beliefin a

spray-relatedtensile strainproblemfollowing the detectionof a mold

disorder.

460
OPERATINGPARAMETERS[

INPUT

MAINMODULE

Analysisofspecificitassocia y, ted

withthe mostimportant problem

MODULE1 [ ] MODULE2 ] I MODULE3 [

Figure 9 Ageneralflow sheetrepresenting the structure of theexpertsystem.

461
Table I Internal Cracks in Billet Casting

QualityProblems Location Causes InfluencingFactors

Off-cornercrack Lowerpartof mold Bulgingofthesolid Thermomechanicalbehaviorof

or verycloseto shelland hingingat the mold;adversemold-shell

moldexit off-corners interaction;deepand nonuniform

oscillationmarks;steelcomposition and superheat

Diagonalcrack Sprayzone Nonuniformshell Thermomechanicalbehaviorofthe

generatedby mold;adversemold-shellinterthe mold action;asynchronousintermittent

boilingin the mold;deepandnonuniformoscillationmarks;steel

compositionand superheat

Asymmetric Poorspraydesignandmaintenance;

spraycooling steelcompositionand superheat

Centerlinecrack Nearthe pointof Suddendecrease Inadequatespraycoolingnear

complete in the centerline thepointofcompletesolidification;

solidification temperatureatthe steelcompositionand superheat

pointof complete

solidification

Pinchrollcrack Closeto the Squeezingon a Excessivepinchroll pressure;

pinch rolls strandwitha steel compositionand superheat

liquidcore

Unbending Closeto thepoint Unbendingon a Excessivebendingstrains;steel

cracks ofunbending strandwitha compositionand superheat;high

liquid center castingspeed

462
Table II Midway Cracks in Billet Casting

Locations Causes InfluencingFactors

•Moldexitor in thegap Reheatingofthe Mismatchbetweenthe moldand thespraysdue to

betweenthe mold billetsurface designor maintenanceproblem;poor designofcooling

and the sprays jacketnearthemoldexit;steelcompositionandsuperheat

Upperportion of Reheatingofthe Poorspraymaintenancedue tobent or pluggedspray

the sprays billetsurface nozzles;steelcompositionand superheat

Lowerportionof the Reheatingofthe Designand maintenanceissuesforthe sprays;steel

spraysor theradiation billetsurfacedue compositionand superheat

coolingzone tothe sprays

Reheatingofdark Thermomechanicalbehaviorofthemold;adversemoldovercooledpatches shellinteraction;deepandnonuniformoscillationmarks;

generatedbythe mold steelcompositionand superheat

463
Table III Surface Cracksin Billet Casting

QualityProblems Origins Causes InfluencingFactors

Transversecrack Inthe mold Pullingactionon the Thermomechanicalbehaviorofthe

(and depression) strandas a resultof mold; adversemold-shellinteracbindingor suckingin tion;deep and nonuniformoscillathe mold tionmarks;steelcompositionand

superheat

Longitudinal Inthe mold Reheatingof the Largecorner radius;presenceof

corner crack corner dueto a large corner "keyholes,"mold-tube

mold/shellgap alignment;asynchronousintermittentboilingin themold;deep and

and/or nonuniformoscillationmarks;

thermomechanicalbehaviorof the

Thinand weakshellat mold;adversemold-shellinteracthe hottercorners tion;steelcomposition

Longitudinal In the mold Excessivereheatingofa Presenceofscratch or gouge

midfacecrack localizedportion ofthe markson theinnersurfaceof

billetsurface;stream themoldwall;misalignment

impingementon a face ofmetalstream

Crazecrack In thesprays Grainboundaryembrittle- HighlevelofCu,Snor lowmelting

•mentdue tothepresence impuritiesin steel

ofCu,Snor lowmelting

impuritiesin steel

464
Table IV Summary of flhomboidity Problem in Billet Casting

Origins Causes InfluencingFactors

In themold Nonuniformshell Thermomechanicalbehaviorofthemold;adversemoldand/or the generatedin the mold shellinteraction;asynchronousintermittentboilingin

sprays themold; deepand nonuniformoscillationmarks;

mold-tubealignment;steelsuperheat

In thesprays Asymmetricspraycooling Poorspraydesignand maintenance;steelsuperheat

465
Table V Summa_ of Breakout Problems in Billet Casting

Origins Causes InfluencingFactors

Closeto obtuse- Thinshellsgeneratedatthe Thermomechanicalbehaviorof themold;

anglecorners of obtuse-anglecorners due to adversemold-sheUinteraction;deepand nonthestrand 'asymmetricalcooling uniformoscillationmarks;Mold-tubealignment;

in themold steelsuperheat

Closeto transverse Localreductionin the shell Adversemold-sheUinteraction;deepand nondepressionsor thicknessdue to thepresence uniformoscillationmarks;thermomechanical

deep oscillation of depressionsor deep behaviorof the mold

markson the oscillationmarks

billetsurface

Closeto a weak Inadequateshell thickness Insufficien.dwell t timein themold;entrapment

spotin the shell atthemoldexit ofslagor scumbetweenmoldand billet

Moldoverflow Operatorerror Poor metalcontrol

466
Table VI Initial Scheme Proposed by the Expertsfor the Analysis of Midway Cracks

Originating in the Radiation Zone

Stages Details

1 Input Distancefromtheoutertipof thecrack to thebilletsurface

2 Compare Measureddistancewithsolidshellthicknessprofile

3 Establish Locationof crack originin the machine

4 Input. Modelpredictedbilletsurface reheatforradiationzone;sprayparameters- zone

lengthand waterflowrate; hightemperaturestrengthofsteel- Mn:Sratio;cast

structure- superheatlevel

5 Analyze Compareinputparameterswithvaluesspecifiedbytheexperts

6 Correlate Generationof midwaycrackwiththe operatingparameters

7 Conclude Conclusionsand justification

467
Table VII Definition of a Fuzz, Setfor

the Adjective "High"

Radiationzone reheat

temperature(°C) 0 50 75 100 150

Degreeof beliefin a

highreheat (%) 0 25 50 75 100

468
Table VIII Examples of the Successful Diagnosis of Quality Problems

Company Commentson theAnalysis

A The systemrelateda problemwithrhomboidityto pluggedspray nozzles.The operators

solvedthis problembyimprovingthespraycoolingwaterquality.

B Off-comercracks were found to originatenear the mold exit.The systemsuggesteda

mismatchbetweensprayandmoldheatextractionratesduetoa largegapbetweenthemold

exitand thefirstspraynozzle.

C Theheattransfermodelcalculateda highreheatintheradiationzone.Midwaycrackswere

seen in the radiationzone.Thecause ofthis highreheatwasa shortsprayzone.

469

UNDERSTANDING PHASE DIAGRAMS

Patricia J. Olesak

MET Department

Purdue University

1417 Knoy Hall - Room 115

West Lafayette, Indiana 47907-1417

Telephone 317-494-7532

471
472
Understanding Phase Diagrams

Patricia J. Olesak

Purdue University,West Lafayette,IN

KeyWords: phases, liquidus,solidus,solvus,eutectic reaction

Prerequisite Knowledge: General knowledgeof phase transformations as affected by

temperature and composition.

Objective: To assiststudentsin understanding phase diagrams. Emphasis is placed on the

use of the lever law,and interpretation of the phase diagrams.

Equipment: IBM compatible computer whichruns MS-DOS or PC-DOS,with a minimum

hardware configuration of 256Kwith CGA. Softwareisthe "Useof Phase Diagrams",

Engineering Materials Software Series,Dahl, K. S.,Van Tyne,C.J., Institute of Metals,

London.

Introduction: The topic ofphase diagramsisnever an easy subjectfor studentsto

understand. Lectures, and homework assignmentsusing the "leverlaw"may assist

understanding, but students seem to stumble over thisrelatively easytopic, despite the

many waysthe subject is covered.

In an attempt to present this subject in lab,I have begun using a softwareprogram which

illustrates various phase diagram on the computer screen and usesthe lever law to

calculate weight fractionsof a phase. This same program islater used in a junior-level

course to coverthe subjectsof solidification,heat treatment and an in-depth study of phase

diagrams.

Procedure: Students are givena write-up whichinstructsthem on the use of the program.

They begin by selecting the simplediagrams or eutectics option. There are several alloy

systemslisted. Once a selection is made, the user is asked ifthey wouldlike a phase

analysis,or fraction chart (amount vs. composition,or amount vs.temperature). When

phase analysisis chosen,the phase diagram is displayed. A temperature and composition

must be specified to see your location (asterisk designation) on the phase diagram. The

results from use of the leverlaw, as well as phase compositionsusing a tie line are then

shown.

__ _...[ Temp Phase Co__osltion _ount

1480 _"_'_'"_ 1300.0 Gamma 98.7Fe-1.3C 68.1X

\ , -,,. L Liquid 97._e-3._ 39.9"/.

0 _.,.

C12f_ , _,,___. 7'

1B(]8 /

A

"'/ t

•Fe 1 2 3 d C

HeightPercentaBeCarbon

Figure 1. Fe-Cphase diagram with

compositionsand weightfractionsof

phases noted for a 2.0% C alloy at 1300°C.

473
Figure 1 illustratesthe Fe-C phase diagram that isshownon the computer screen. A

temperature of 1300°Cand a composition of 2.0%C has been selected. As shown,the

weightfraction of gamma is 60.1%and the weight traction of liquid is 39.9% The

composition of the gamma phase is 98.7Fe - 1.3C and the composition of the liquid is 97.0

Fe - 3.0 C.

If fraction charts are specified, a plot of the amount of each phase present as a function of

either temperature or composition isgiven. Figure 2 illustrates a weight fraction chart for

the Fe-C alloysystemat a temperature of 800°C.

1400 \\ "" "-'i L

C 1_ I_ " t 1--._L---- I

\ _, / _" + IC

"" i II

m i_ f

o 58 58

u ._

t B 7 "/" "

X Fe 1 2 3 4 C

Weigh'LPercentageCarbon

Figure 2. Weightfraction chart

for the Fe-C alloysystemat 800°C.

In a junior-level materials course, solidificationisstudied. When the solificationoption is

chosen,the phase diagram, cooling curveand rnicrostructure of the solidifyingmaterial is

shown on the screen. Figure 3-6 illustrate the screens that are presented for the

solidificationof the hypereutectic alloy.

474
solidificationof a hypereutec_ialc loy

Figure 3. Solidificationof a 10%B

alloy. Microstructure isliquid.

,i

I I I \ _o,,og_rv,

°C 300 I

21_ _..__ ,/ t

i°°_I/ii I Ii --i

0 x II I

A .10_ 30405868TO 80 90B Time"_

WeightPercentaaeB

solidification ofa hypereutectic alloy

Figure4. Solidificationof a 10% B

al!oy. Proeutectic B is present in the lmcrostructure.

475
580 i _" Coo!in9Curve

400 • , \

"_>F"-F-4I.._b.

0

A 10 20 :-8 40_ 60 78 80 _ B Time.-. -',

I,'JeightPercentageI3

solidification ofa hypereu_ectic alloy

Figure 5. Solidificationof a 10% B

alloy. Proeutectic B is growingand the

eutectic (A + B) isbeginning to form.

=olidifica'cio{na hypereutectlcalloy eu'_ec'c__ic

Figure 6. Solidificationof a 10%B

AllOy.Proeutectie B and eutectic

+ B) ispresent in the microstructure.

476
Students are required to complete a table, whichasksfor the weightfractions and

composition of 20 alloy/temperature combinations. The programwillshowstudents the

correct answers,but all answersmust be verifiedby hand using the lever rule, and tie line.

I have found that students enjoylearning from a computer (even the subject of phase

diagrams). They begin to learn how to interpret phase diagrams,and understand the use of

the tie line and leverrule. This programhelps students to understand the difference

between composition and weight fraction, and also between eutectie and eutectoid

reactions. The subject of phase transformation and the interpretation of phase diagramsis

a difficultsubject for studentsto understand, but I believe thissoftware program helps

studentsto better grasp a difficultsubject.

Note to Instructor: The lab write-up consistsof a general tutorial for using the software,

alongwith the problem assignment. This exerciseis best presented in a self-taught

envaronment,where studentslearn for themselves. Theyshould be able to pace themselves

depending on their computer skills,understanding of the subject,etc.. The instructor

serves as a reference, but does not "teach"the subject.

References:

Dahl, ICS.,van Tyne, C.J., The Use of Phase Diagrams,operating manual, Institute of

Metals, London, England, 1988.

477

PRECISION MEASUREMENTS OF THE MICROWAVE

DIELECTRIC CONSTANTS OF POLYVINYL

STEARATE AND POLYVINYLIDENE FLUORIDE AS A

FUNCTION OF FREQUENCY AND TEMPERATURE

Jai N. Dahiya

Physics Department

Southeast Missouri State University

One University Plaza

Mail Stop 6600

Cape Girardeau, Missouri 63701

Telephone 314-651-2390

479
480
Precision Measurementsof the MicrowaveDielectric Constants

of Polyvinyl Stearate and Polyvinylidene Fluoride

as a Function of FrequencyandTemperature.

O. N. Dahtya

Physics Department

Southeast Missouri State University

CapeGtrardeau, Missouri

KEYWORDS

Dielectric constant, microwaveresonant cavity, polymers and Dielectric

relaxation.

OB3ECTIVES

1. To tune a microwaveresonant cavity.

2. To operatea microwavespectrometerat differentfrequencies.

3. To operatethermalbathsforheatingand coolingthe resonantcavity.

4. To studydielectricrelaxationand analyzedatafor dielectricconstant

measurement.

SUMMARY

A microwavespectrometerin the x-bandof frequenciesis designedto

studydielectricbehaviorof polarand non-polarmolecules,l'heresonant

cavityin the spectrometeris usedas a probeto determinethe complex

permittivityof a sampleof polyvinylstearateandpolyvinylidenefluoride.A

verysensitiveheatingand coolingtechniqueis designedto studythe

microwaveresponseof thesematerialsat differenttemperatures.The realand

imaginarypartsof the complexpermittivityare calculatedby usingSlater's

perturbationequationsand Debye'sequationsare usedto calculatethe

relaxationtimes.

INTRODUCTION

Polymersare largemoleculesof nonmetallicelementscomposedof many

repetitiveunitscalledmersjustas crystalshavemany unitcells. The

polymermoleculesarevery largein sizeand becauseof thistheyare often

knownas macromolecules.The molecularsizesof the polymerscan be defined

in termsof the degreeof polymerizationwhichis the ratioof themolecular

481
weightof themoleculeto itsmer'sweight. Polyvinylstearaterepresentsa

numberof groupsof polymerslikepolyacrylatesand polyvinylesters. The

polyvinylsare linearmolecules.Thesemoleculespossessa chainof carbon

atomsthatare covalentlybonded. Vinylidenepolymersare producedwhentwo

of the hydrogenatomsin ethyleneare beingsubstitutedby a groupof atoms.

When a stressis appliedto suchmaterial,the largeratoms,suchas chlorine

or fluorineinterferewiththe slidingof the chainsand thisprocess

increasesthe strengthof the polymer.

The presentexperimentinvolvesthe use of a microwaveresonantcavity

in the TEolzmodeto studythe dielectricresponseof polyvinylstearateand

polyvinylidenefluorideat microwavefrequenciesof 9.2 and9.7 GHz. The

dielectricrelaxationof thesepolymersis alsostudiedas a functionof

temperature.It has provento be a very interestingexperimentto findthe

dielectricresponseof a materialneara phasetransitionregioni.e.,going

froman orderedto a disorderedphase. Itwas shownby Smyth(Ref.I) that

frommeasurementsof the staticdielectricconstantof compoundsas a function

of the temperature,importantconclusionsconcerningmolecularfreedommay be

drawn. A numberof experimentshavebeendoneto studythe dielectric

behaviorof a numberof:liquidsand solids(2-7). The dielectricresponseof

a polarliquidshowsa largechangeat the freezingpoint. A typicalexample

is thatof nitromethaneas studiedby SmythandWalls (Ref.8). The

measurementsof thispolarsubstancewerecarriedout at a frequencyof about

7 x 104Hz. The drop in the dielectricconstantof nitromethanefrom45.5to

3.93 at the freezingpointis causedby the partialor completelossof

rotationalpolarization(freedomto reorient),whilethe electronicand

vibrationalpolarizationremainrelativelyunchanged.Smythand Hitchcock

(Ref.g) made similarmeasurementson nitrobenzeneand foundthatthe dipole

482
relaxationoccurredat ratherlargefrequencies.On the basisof the x-ray

studies,indicationsof side-chaincrystallinityhavebeenreportedfor

polyvinylestersand polyacrylates(Ref.10 and 11). The roomtemperature

valuesof the dielectricconstantandlosstangentfor the polyethyleneare

2.25 and lessthan0.0002respectivelyas shownby Von Hippel(Ref.12).

THEORY

In his theoryof polarmolecules,Debye(Ref.13)explainedthe relaxation

phenomenonand showedthatpolarizationof a dielectricmediumin an electric

fieldmightarisefromthe partialorientationof permanentmoleculardipoles

by the fieldas well as fromthe distortionof electronicorbitsin the

molecules.The theorystartsfroman assumptionaboutthe timevariationof

the polarizationin responseto a stepfunctionremovalof the field. The

simplestassumptionis of an exponentialdecay:

P(t) = Po e-t/' (i)

wherePois the polarizationof themediumin the presenceof an appliedfield

in the formof a stepfunction,P(t)is the timeresponseof the polarization

when the appliedfieldis removedand_ is the relaxationtime.

Further,usinghis simplemodel,Debyeexplainedthe processof

molecularrelaxationby assumingthe dipolarmoleculeto be a sphereof radius

a movingin a continuousviscousfluidpossessinga coefficientof internal

friction_ and obtainedan expressionforthe relaxationtime

- 4xa3

kT _ (2)

wherek istheBoltzmannconstant, 's T istheabsolutetemperature, a isthe

radiusof the Debyesphereand9 is the viscosityof the medium.

483
The aboveequationis validfor systemsin whichthereis no interaction

betweendipoles. This requiresdilutesolutionsof dipolarmoleculesin a

non-polarliquid.

The factthatthe relaxationtimedependsso stronglyon the temperature

indicatesthatat some stagein the relaxationprocessa particleneedsa

certainamountof energyin excessof the averagethermalenergyto overcomea

potentialbarrier. Thus,the exponentialtemperaturedependenceof _ and_ is

similarto thatof chemicalreactionrateswherewe alsodealwith the case

that a particlehas to acquirea certainactivationfreeenergy. This

possibilityof approachingthe dielectricrelaxationfromthe standpointof

chemicalratetheorywas firstpointedout by Eyring(Ref.14) and developed

by Kauzmann(Ref.15).

The dielectricpropertiesof differentmaterialscan be expressedin

termsof the complexpermeability_*, the complexpermittivity€*, and their

relativelosstangents.Theseare expressedas follows.

I_*= P/ - dl_// (3)

with

tan_ = /_ (4}

where_' and_" are the realand imaginarypartsof the complexpermeability.

and

{.= {l_ j_, (s)

484
with

tan6 - --_ (6)

€I

where{' and {" arethe realand imaginarypartsof the complexpermittivity.

The polarizationof a certainmaterialcan be measuredin termsof these

quantities(_* and€*). Dispersionis shownin a numberof materialswith

variationof the complexpermeabilityandthe complexpermittivity.Thereare

basicallytwo differentkindsof dispersionshowninmaterials. In the first

typeof dispersionthe polarizationsareunableto followthe fieldsat higher

frequencies.This is knownas the Debyerelaxation.The secondtypeof

dispersionis associatedwith quantizedtransitionstakingplacefromone

energylevelto anotherin the atomor molecule.

Accordingto Slater'sperturbationtheoryforresonantcavities,the

phaseshiftand the cavityQ changesare functionsof the dielectric

propertiesand itsperturbationchange(Ref.16). Onlythe finalresultsare

givenhereand are:

A_ av

(_)_- (7) f_._adV

and

I dv

A (--_)= f_._adv (8)

is the angularfrequency2xf,wheref is in Hertz. A_/_ is the phaseshift,

E representsthe electricfieldof the perturbedcavity,Eais the electric

fieldof the unperturbedcavity,Esis the localfieldof the sample,and v

and V are the volumesof the sampleand the cavity,respectively.

485
EXPERIMENTALPROCEDUREANDRESULTS

A microwaveresonant cavity in the TE0nmodewas used as a probe in a

microwavespectrometer in the x-band of frequencies. The details of this

spectrometer are given elsewhere (Ref. 2) but for conveniencea block diagram

is shownin Figure ] with major components. A 2k25 klystron is used in this

experiment and this is slightly tunable around9.0 GHz. The dielectric

behavior of polyvinyl stearate wasstudied at 9.2 GHzas a function of

temperatureandthatof polyvinylidenefluoridewas studiedas a functionof

frequencybetween8.8 and 9.7 GHz. Figure2 showsthe schematicfor a very

sensitivethermalbathfor heatingandcoolingthe cavityto get desired

temperaturefor dielectricrelaxatonstudies.

The shiftin o and changein Q aredependentuponthe locationas well

as the dielectricnatureof the perturbingsample. In thisexperimentthe

perturbingsamplewas placedalongthe symmetryaxisof the cylindrical

cavity. The resultantchangein o and changein Q were monitoredas the

cavitytemperaturewas varied. The two parameters,o and Q are relatedto the

realand imaginarypartsof the complexpemittivity(€*)of the perturbing

sampleandmeasurementson thesetwoparametersenablethe valuesfor{' and

€" to be obtainedvia Equations7 and8 respectively.

Figures3 and 4 showthe behaviorof frequencyshiftand Q-changeas a

functionof temperature.FromSlater'sequations(#7and8) one can see that

the frequencyshiftsare relatedto {' the realpartof the dielectric

constantand the Q-changeson the otherhandare relatedto _", the imaginary

partof the complexdielectricconstant(_*). As can be seen fromthese

figuresthatthereis a dramaticchangein the dielectricbehaviorof

polyvinylstearatenearits phasetransitiontemperatureof about51.6°C. The

real and imaginarypartsof the complexpermittivitychangesharplyaround

486
thattemperature.The realpartof the dielectricconstant({')remains

constantafterthe phasetransitiontemperaturebut the imaginarypart ({")

showsa uniformdecreaseas thetemperatureis changedup to aroundI00°C.

Figures5 and 6 displaythedielectricbehaviorfor a sampleof

polyvinylidenefluorideas a functionof frequency.The frequencyshiftthat

correspondsto the realpartof thedielectricconstantshowshighervaluesat

lowerfrequencies.Rightaround9.3GHz thereseemsto be a discontinuityin

thevalueof the dielectricconstantand afterthat it decreasesup to a

frequencyof about9.6 GHz and thenlevelsoff. The dielectriclossterm ({")

showsan increaseas the frequencyincreasesup to aroundg.2 GHz andthen its

valuedecreasesas the frequencyincreases.

Microwaveresonantcavityused in thisexperimentwas very successfulin

monitoringthe phasechangesin polyvinylstearateandpolyvinylidene

fluoride.The dielectricbehaviorof thesetwo polymerswas studiedvery

preciselywith thistechnique.The thermalbathdesignedto take thedata at

varioustemperaturewas verysensitive.With thistechniquethe temperature

of the samplecouldbe maintainedat a desiredvalueto studythe dielectric

behaviormorepreciselyat thatvalue. It is verycriticalto maintainthe

temperatureof the substanceunderstudyas it goes throughits phase

transitiontemperature.In thisexperimentthiscouldbe achievedvery

successfully.

487
REFERENCES

I. Smyth,C. P.: DielectricPolarizationof LiquidsV. Atomic

Polarization.J. Am. Chem.Soc.,51, 1929,p. 2051.

2. Dahiya,J. N.,Jani,S. K., andRoberts,J. A.: PhaseTransition

Studiesin Polarand Non-PolarLiquidsat MicrowaveFrequencies.J.

Chem.Phys,74(6),1981,p. 3609.

3. Benedict,T. S., and Durand,J. L.: DielectricPropertiesof Single

DomainCrystalsof BaTi03at MicrowaveFrequencies.Phys.Rev.109,

1958,p. 1091.

4. Birnbaum,G., and Franeau,J.: Measurementsof the Dielectricand Loss

of Solidsand Liquidsby a CavityPerturbationMethod.J. Appl.Phys.,

20, 1949,p. 817.

5. Collie,C. H., Hasted,J. B., and Ritson,D.M.: The Dielectric

Propertiesof Waterand HeavyWater. Proc.Phys.Soc.,60, 1948,

p. 145.

6. Crouch,G. E.: DielectricMeasurementof Liquidsat Microwave

Frequencies.J. Chem.Phys.,16, 1948,p. 364.

7. Gevers,M.: Measuringthe DielectricConstantand the LossAngleof

Solidsat 3,000Mc/s. PhilipsTech.Rev.,13, 1951,p. 61.

8. Smyth,C. P., andWills,W. S.: DielectricInvestigationson

Nitromethaneand Chloropicrin.J. Chem.Phys.,3, 1935,p. 557.

9. Smyth,C. P., and Hitchcock,C. S.: DipoleRotationin Crystalline

Solids. J. Am. Chem.Soc.,54, 1932,p. 4631.

10. Fitzgerald,EdwinR.: MechanicalResonanceDispersionin Crystalline

Polymersat Audio-Frequencies.J. Chem.Phys.,27, 1957,p..1180.

11. Fitzgerald,EdwinR.: DynamicMechanicalPropertiesof Polyvinyl

Stearateat Audio-Frequencies.J. Appl.Phys.,29, 1958,p. 1442.

12. Von Hippel,A. R.: Editor,TechnologyPressof M.I.T.and J. Wileyand

Sons,N.Y.,1954.

13. Debye,P.: PolarMolecules.ChemicalCatalog,New York,1929,Chap.V.

14. Stearn,AllenE., and Eyring,Henry: The Deductionof Reaction

mechanismfromtheTheoryof AbsoluteRates. J. Chem.Phys.,5, 1937,

p. 113.

15. Kauzmann,Walter: DielectricRelaxationas a ChemicalRateProcess.

Rev.Mod.Phys.,14, 1942,p. 12.

16L Slater,J. C.: PerturbationTheoryfor ResonantCavities.Rev.Mod.

Phys.,18, 1946,p. 441.

488
I 

POWER 

SUPPLY 

PRINTER 

I 

KLYSTRON 

? 

1. Block diagram of the microwave spectrometer used in this experiment. 

- DIRECTIONAL WAVEMETER ATTENTUATOR - COUPLER 

RESONANT MICRO- - - CAVITY - 

COMPUTER 

I I 

1- INTERFACE 

FM PREEXTERNAL MODULATED GENERATOR AMPLIFIER 

u 

MODULATION 

FREQUENCY 

i 

MARKERS 

SIGNAL OSCILLOSCOPE 
2. Block diagram of the heating and cooling system used in this experiment. 
Temperature (OC) 

Frequency shift (Af) as a function of temperature for a sample of 

polyvinyl stearate. 
Temperature (OC) 

4. Quantity f,. A(l/Q) as a function of temperature for a sample of 

polyvinyl stearate. 
Frequency (GH Z) 

5. Frequency shift (Af) as a function of the microwave resonant frequency 

for a sample of polyvinyl idene fluoride. 
Frequency (GH ,)

6. Quantity f,. A(l/Q) as a function of the microwave resonant frequency 

for a sample of polyvinyl idene fluoride. 
EXPLORING THE CRYSTAL

STRUCTURE OF METALS

Richard P. Krepski

Principal Researcher

Intermet Technology

1306 Airport Road

Aliquippa, Pennsylvania 15001

Telephone 412-378-3781

495
496
EXPLORING THE CRYSTAL STRUCTURE OF METALS

Richard P. Krepski

Principal Researcher

Intermet Technology

Aliquippa, Pennsylvania

-andInstructor, Dept. of Engineering

Geneva College

Beaver Falls, Pennsylvania

KEY WORDS: Crystal Structure, Cleavage, Plastic Deformation,

Alloys, Glassy (Amorphous) Structure

PREREQUISITE KNOWLEDGE: Introduction to crystal structure and

atomic bonding, as covered in a middle school or junior high

school earth science class.

OBJECTIVE: These activities are intended to supplement

the study of mineral crystal structure in a middle school earth

science class. The simple metallic close-packed structures are

explored through model building, and differences in structure

are related to mechanical behavior. The concepts of alloying

and glassy (amorphous) stucture are introduced, and give

students a glimpse of what a materials scientist does. Some of

these approaches may prove useful in a college-level

introductory materials science class.

EQUIPMENT/MATERIALS:

1. Magnetic Marbles (120 required for student activity and

permanent models)

2. Spray Craft Glaze

3. Zinc, Zinc-Aluminum, and Aluminum Rods, and Jig for Holding

Both Ends of Rod for Impact Test.

4. Galvanized steel with distinctive surface grains or

"spangles".

5. Hammer

INTRODUCTION

Crystal structure generally holds the fascination of students

at the middle school/junior high level, because of the inherent

beauty of faceted mineral crystals. Standard curriculum

typically includes identification of mineral samples,

introduction to the various crystal lattice symmetries, and

discussion of the kinds of atomic bonds. Metallic structures

receive minimal attention.

Using magnetic marbles, studentsare challengedto construct

the two close packed metallic crystal structures. These

497

I
activities can be structured as team races to stimulate

interest. Differences in structure can be related to

deformation behavior, and this relationship can be demonstrated

by a simple impact test.

MAGNETIC BALL MODELS OF CLOSE-PACKED METAL STRUCTURES

The simplified picture of the metallic bond is that of core

atoms packed in a "sea" of di_ssociated valence electrons.

This allows construction of models of the two close-packed

structures using magnetic marbles. (Students should be

reminded that the forces holding the atoms together are not the

same as the magnetic attraction holding the marbles together.)

A good in-class approach is to have two groups of four students

participate in a race to build a closest-packed structure (boys

vs. girls works well). Each student is given seven marbles.

The first task is to make a layer of the seven "atoms" that is

as tightly packed as possible. Most students can accomplish

this fairly quickly. The easiest way is to make a row of six

marbles, close it into a circle, and then place the seventh

marble in the center. The real challenge is to stack these

layers to make a three dimensional structure that is also as

tightly packed as possible. Students often start with a

structure having the center atom of each layer aligned. This

causes the center atom of the top layer to stick out, and is

not a closest packed structure. Closest packing can be

attained by putting the second layer above the B or C hole

sites in the first layer, and similarly nestling subsequent

layers in the holes of the layer below it (Figure 1).

FIGURE 1

Stacking Sequences in Close-Packed Crystal Structures

(from R.E. Reed-Hill, Physical Metallurgy Principles, Van

Nostrand Reinhold Co., New York, 1964)

Once the students' race is over, the instructor can explore

details of the structures. It is helpful to "cheat" by

building models with layers that have been glued together using

498
spray craft glaze. There are two basic options in stacking,

the ABAB sequence of the hexagonal close-packed structure, and

the ABCA of the face-centered cubic structure. (I do not

mention face-centered cubic to younger students, as it tends to

confuse them; instructors should be able to point out the faces

of the cubic unit cell revealed by the model).

By adding individual marbles to the ABCA stacking arrangement,

students can discover a key aspect of this structure: diagonal

planes have the same close-packed symmetry as the base plane.

On the other hand, the ABAB stacking arrangement has close

packed layers only on the horiontal plane of the model. This

subtle difference in structure makes a tremendous difference in

mechanical behavior.

RELATION OF CRYSTAL STRUCTURE TO MECHANICAL BEHAVIOR

Assembly of the ABAB and ABCA models reveals an important

relationship between metallic crystal structure and mechanical

behavior. The ABCA model displays diagonal faces that have the

same tightly packed arrangement as the base. This structure is

associated with metals like aluminum and copper, which can be

easily bent. For metals to "plastically deform", atoms have to

slide over each other. This occurs more easily on these tightly

packed planes. Aluminum deforms easily because it has many of

these planes in different orientations. On the other hand,

crystals of zinc and magnesium have the ABAB structure, and

atoms slide easily only on the base layer. Zinc tends to break

or "cleave" along crystal faces when it is struck with too much

energy. (I generally avoid the concept of dislocations when

presenting this material at the pre-college level).

To reinforce this concept, a simple impact test is performed

using rods of aluminum, zinc, and zinc-5 wt.% aluminum alloy.

The rods are supported at both ends in a jig, and impacted with

a hammer. (Students should wear eye protection to guard

against flying pieces of metal). The aluminum bar will bend,

while the zinc will break by cleavage, revealing the crystal

structure inside the metal. Students should note that the zinc

is not one big crystal, but a number of little crystals or

"grains". The grain structure of zinc can also be seen in a

sample of galvanized steel, which has a coating of zinc

deposited on it for corrosion protection.

If zinc and aluminum have such different properties, what will

be the behavior of a blend of the two? Such a blend is called

an "alloy". Hammer impact of the rod of zinc with 5% (by

weight) aluminum will reveal its strength and toughness. At

high magnification, the internal structure of this alloy is

revealed as a fine assembly of zinc-rich and aluminum-rich

regions, each with its characteristic crystal structure (Figure

2). The instructor should explain how a microscopic image like

Figure 2 is obtained: a small piece of the metal is mounted in

499
plastic, polished to a mirror finish, and then etched with an

acid. The alloying of a metal to improve its properties is a

good example of what a materials scientist does. By

understanding the structure of a material and how it controls

properties, we can design new materials that are stronger,

tougher, lighter, more durable, more reliable, less costly, and

better for the environment.

FIGURE 2

Microstructure of Zinc-5wt.% Aluminum Alloy; 1000X

GLASSY OR AMORPHOUS STRUCTURE

A final game with the magnetic marbles can be used to show the

difference between crystalline and glassy (amorphous)

structure. We have seen that crystals have an orderly

arrangement of atoms. Nature makes these structures because

they have a low energy associated with them. The other

alternative is the structure of a glass, which has no long

range order in the packing of the atoms. This occurs because

different atoms do not fit together well, or are cooled from

the liquid or vapor state so quickly that there is no time for

the atoms to arrange themselves into crystals.

Two student volunteers are picked for a race to build a glassy

stru_ur_ using the _agnet_c _rbles. As an incent£Te, the

winner gets to keep the marbles. However, the loser has to

perform a horrible homework assignment. This may decrease the

pool of volunteers, but usually there are a few students game

500
enough to try. The fact is that the race is fixed so that both

students win. As soon as the race starts it is over, because

any random cluster of marbles will have an amorphous structure.

This reinforces the notion that rapid cooling from the liquid

state can "freeze in" the glassy structure. Obsidian is a good

mineral example of rapidly cooled glass. Snowflake obsidian

shows crystals of quartz starting to form in the glassy matrix.

Window glass is another example - in this case the complex

chemistry of the silicate glass gives an amorphous structure

even if it is cooled fairly slowly. Actually, many metallic

alloys can be amorphous if they are quenched from the liquid

state quickly enough (on the order of a million degrees

centigrade per second!) Amorphous metals can have unusual and

advantageous properties, and provide another example of the

work of the materials scientist.

NOTES TO THE INSTRUCTOR:

1. Magnetic marbles are available from Edmund Scientific Co.,

(609) 573-6250.

2. Zinc, aluminum, and zinc-aluminum alloy rods are available

from Intermet Technology, 1306 Airport Rd., Aliquippa, PA

15001, (412)378-3781.

3. If this presentation is made by a visiting professional, it

is a good idea to give every student something to keep. I like

to have a pre-cracked zinc rod for every two students.

Students can break these by hand to reveal the cleaved facets

of the cast grain structue.

ACKNOWLEDGEMENTS

This material was developed under a National Science Foundation

SBIR grant to Intermet Technology. In-class presentations were

performed under the "PRISM" program coordinated by

ASH-International. Zinc Corp. of America provided zinc samples

and access to metallographic equipment.

501

FLUIDS WITH MAGNETIC PERSONALITIES

Glenn S. Kohne

Department of Electrical Engineering and Engineering Science

Loyola College

4501 North Charles Street, DS-224

Baltimore, Maryland 21210-2699

Telephone 410-617-2249

503
5114
Fluids with Magnetic Personalities

Glenn S. Kohne

Associate Professor of Electrical Engineering &

Engineering Science

Loyola College

Baltimore, Maryland

Key Words: Magnetorheological,Electrorheological,VariableViscosity

Prerequisite Knowledge: Basicprinciplesof electricity,magnetism,electromagnetismandviscosity.

Objective: To introducethe scienceofrheology. To observethebehaviorcharacteristicsof

magnetorheologicalfluids. To demonstrateseveralpracticalapplicationsof thesefluids. To suggest

somepossiblestudentlaboratoryexperimentsusingmagnetorheologicalfluidswhichprovidedata

suitablefor variouserror andstatisticalanalyses.

Equipment:

1. Vegetable Oil (& possibly otherthin oils)

2. Iron Filings

3. Various plastic bottles, tubing and Goop adhesive

4. DC power supply (2-3 amps @1-5 volts)

5. SmallDC motor

6. 26-30 gauge wire

7. Severalstrong permanent magnets

8. Several 2 liter plastic soft drink bottles

9. Plastic Tubing, 5/16 OD, 3/16 ID, 5 feet long

505
Introduction to the Science of Rheology:

The termtheology meansliterallythe studyof flow. As a science, the fieldofrheology concernsitself

with allaspectsof deformationof real bodiesunderthe influenceof externalstress. Intraditional

mechanics,the responseof real bodiesto externalstressisstudiedusing idealizedbodies suchas anideal

elasticbody or an ideal viscous(Newtonian) fluid which exactly obeycertainphysicallaws. These

classicalmodelsareof practicalvalue for classes of materialswhere the modeledpropertydominatesthe

characteristicbehaviorof the material.

Real materialswhose propertiesandbehaviorcan be approximatedby one of the classicalmodelsunder

one set of conditions will exhibk a differenttype of behaviorunder other properly chosen conditions.

Somematerials cannot be adequately described by any classicalmodel because they exhibit properties

characteristicof differentmodels at the same time. Rheology as a science is concerned with the behavior

of real materialswhich exhibit,to an extent that cannot be neglected, more than one fundamental

property of deformationunder external stress, such as elasticity and viscosity. While classicalmechanics

treats the solid state and the fluid state of materials separately,theology dealswith phenomenawhich

occur in a verybroad intermediate range between the solid and fluid state.

Phenomenologicalrheology (macrorheology) deals with real materialson a macroscopic scale and

ignores the molecular nature of the material. This allowsthe development of mathematicallycontinuous

functionswith experimentallydeterminedparameters (coefficients)to model the observed behavior of the

material[_1.The experimentalapparatus presented herein can be used to provide the observational data

necessaryto develop andexplore basicmathematically-continuousmodels of theological materials.

Magnetorheological Fluids

Magnetorheologicalfluidsare fluidswhich exhibitthe propertythattheirviscosityis a functionof the

strengthof the magnetic fieldinwhich they areimmersed. Ina very weakmagnetic field,the material

behaves as a fluid. In a strongmagneticfield,the materialbehaves as a thickslush or a weak solid. The

relationshipbetween the viscosity of the fluidand the magnetic fieldis continuouslyadjustableby varying

the concentrationof the magneticmaterialsuspendedin the magnetorheologicalfluidor by selecting a

differentviscosity oil asthe baseof the magnetorheologicalfluid.

Basically,a magnetorheologicalfluidis a suspensionof magneticpanicles such asironfilingsin a host

liquidwhich istypicallya light oilsuchas lightmachineoil, soybeanoil or othervegetable oil. Whenthe

fluidis immersedin a magneticfield,the ironfilingstendto alignthemselveswith the magneticfieldand

canforman elaboratesolidmatrixif they areplentifulenoughfor continuousphysicalcontact with each

other. The oil tendsto adhereto the rigidlyheldironfilings. Obviously,the higherthe concentrationof

the ironfilings,the less likelythe surroundingoil will be overcomewith the gravitationaltendencyto

flow. Onthe down side,the ironfilingstendto be highlyabrasivewhenin contactwith other solids

havingrelativemotionto the magnetorheologicalfluid. Whileincreasingthe densityof the ironfilingsin

the magnetorheologicalfluidimprovesthe solidificationof the fluidin a magneticfield,it increasesthe

abrasioncausedby the fluidto any solid movingwithinthe fluid.

506
Why Magnetorheological Materials

Therearemanyvery , broadclassesofrheologicalmaterialsincludingbiologicalfluidssuchasblood,

saliva,andsynoviafluid l ;polymermeltsandsolutions;suspensions, emulsionsandpastes.

Magnetorheologisucspensionlend s themselvetos introductorylaboratoryworkbecausetheyareeasy

andinexpensiveto create,theydonotrequireexpensiveorspeciallaboratoryequipmenat,ndthey

adequatelydemonstratheolo te gicbehaviors.

Anexperimenust ingelectrorheologicflaluidswaspresentedatNEW:93t21.Considerabapplica le tions

researchhasbeenconductedusingelectrorheologicfluid al s.Thetheologicaeffec l tisbasedprimarilyon

thetendencyofsuspendedordissolvedparticlesormoleculesto alignthemselveswithandremain

stationarywithintheexternallyappliedelectricfieldandto restrictthemovemenoft thesolventor

suspensionliquidt31The . principleprobleminworkingwiththemisthehighvoltage(easily1000V/n'an)

requiredto seetherheologicabehl avior.

Magnetorheologiflcaluids,whichcloselyparallelelectrorheologicfluid al behaviors, aregenerally

suspensionsofmagneticallysusceptibleparticlesinanonmagnetliicquid.Thetheologiceffectisbased

onthetendencyofthesuspendedparticlesto alignthemselveans dremainstationarywithintheexternally

appliedmagneticfieldandto restrictthemovemenoft thesuspensionliquid.Whilemagnetorheologic

fluidstendto bemessy,theyareveryeasyandquitesafeto workwith.Equipmentcanbeassimpleas

vegetableoil,ironfilings,anda horseshoemagnet.Theysatisfactorilydemonstrathee theologic

behavior.

Demonstration #1: Basic Magnetorheologicai Effect

Fluids assumethe shapeof their containerand tend to have flat surfaces(beyondthe meniscusarea).

Solids,andto a lesser extent slurries,tendto retaintheir shaperegardlessof theircontainers.Inthe first

demonstration,the magnetorheologicalfluidis observedto behaveas a fluidin the absenceof a magnetic

field. Whena sufficientlystrongmagneticfieldis applied,the magnetorheologicalfluidcanbe shaped

with a non-magneticspatulainto a formwhich behaves as an almostsolidifiedslurry.When the magnetic

fieldis removed,the fluidrelaxesandassumesthe shapeof its containerwith a flatsurface.

Preparethe fluidbymixingironfilingsinto the oil with a 4 to 1 ratioby weight. Pour the fluidinto the

clear plasticcontainerasinFigure 1a. Stirwith the spatulaand note its behavioras a fluid. Put the

magnetsagainstthe side of the containerand use the spatulato formthe materialinto a bar shapedbridge

between the two magnetsleavingvoids on the perpendicularaxis asinFigurelb. Point out the nonfluid

behavior. Removethe magnetsandnote that the materialbecomesfluidagain.

507
a b

Figure 1. Basic magnetorheological effect demonstration.

Demonstration #2: Fluid Flow Rate Control

The flowrate of a magnetorheologicalfluidcanbemodulatedbyvaryingthefieldstrengthof a magnetic

valveappliedto a tube carryingthe fluid. In thisdemonstration,we canvary(visibly)the flowrate ofthe

magnetorheologicalfluidbyvaryingthe magneticfieldstrengthin the flowvalve.

Prepare the apparatus by drilling 5/16 in holes for the tubing into the two 2-1itersoft drink bottles'

approximately as shown in Figure 2. Cement the two 2 foot lengths of plastic tubing in place using the

Goop and allow to cure for 24 hours. The top tube inFigure 2 serves as an air return during the

demonstration and as a fluid return when bottle B is inverted and raised to prepare for the next

demonstration run. In a separate bottle, prepare 1 liter ofthe. fluidby adding as much iron filing material

(approximately 1/2 pound) as willstay suspended in the oil for 5 minutes. Pour the prepared fluid into

bottle A and seal both bottles. The fluidcan be transferred between bottles A and B by gravity. Move

the fluidto bottle A and shake the bottle prior to beginningthe demonstration. Raise bottle A as high as

possible above B and note the flow rate of the stream into B. Apply the magnetsto the lower tube as

indicated in Figure 1and note the significantlyreduced flow rate. As you move the magnets closer and

further away, you can continuously moderate the flow rate.

A challengingstudent project might be to design and build a flow rate transducer for this apparatus. A

more involved student project might be to explore particle migration as the fluidflows through the tube.

This effect occurs when dispersionsflow through long sections of pipe_41.Flow velocity through the tube

is not uniform. Sheafing stresses decrease fromthe surface of the tube toward the middle. It appears

that the tendency for particlesto migrate toward the center where shearingforces are at a minimumarise

from an imbalance in the torque forces experiencedby the particles in this non-uniform flow.

5O8
Figure 2. Flow control demonstration apparatus.

Demonstration #3: Magnetically Controlled Brake

Magnetorheologicalfluids can perform admirablyas dynamic brakes. In this demonstration, a motor

driven disk will be braked to a varying degree by varyingthe magnetic field applied to the

magnetorheologicalfluidin which the rotating disk is immersed. The effect can be observed by

monitoring either the rpm of the driving motor (at a fixed drivingvoltage) or by monitoring the current

drawn by the drivingmotor (at a fixed drivingvoltage) asthe magnetic field isincreased.

The apparatus can be builtfrom commonlyavailablematerials. The dimensionsof the apparatus are

nominal. The stirringdisk is scrap aluminumcut to a circle somewhat smallerthan the diameter of the

fluidcontainer. It must be center drilledto fit the threaded shaft. It should have several axial cuts

creating pie shaped areas which are to be twisted to form a crude fan. The fan shape servesto help keep

the iron filing suspensionwell mixed. The threaded shaft is brass from a toilet repair kit. The aluminum

disk is mounted on the threaded shaft with two nuts by force fit. The shaft to motor coupling is a piece

of insulation stripped from hook-up wire. For a more permanent situation the motor and shatt can be

joined with Goop or a good epoxy cement.

A student project here might be to better instrumentthe apparatus by adding precisemeasurement of the

motor's rpm. Another might be to develop a 3-D graph showingthe relationshipbetween work done, as

determined by the electricalinput to the system;the magnetic field strength, which could be characterized

by the electrical energy supplied to electromagnets (used in place of the permanent magnets); and the

density of iron filingssuspended in the fluid.

509
Ammeter Power

Supply

::::::::::::::::::::::::::::::::::::::::::::::::::::: •.....,.,.............................,.....,............................ ===================================================

iiiiiiiiiiiiiiiiiiiv iiiiiiJii

..................... •,.,...,..............;......,....?.....;,;.

Figure 3. Magneticallycontrolled brake demonstration.

Notes to the Instructor:

1. Suitablysmall iron fdings are availablefrom Edmund Scientificas part number N60,176.

2. Magnets from Edmund Scientificas part number N40,818.

3. Goop, threaded brass rods, & plastic tubing is available in general hardware stores.

4. Suitable DC motors are from Radio Shack part nos 273-237 or 273-223.

5. Vegetable (soybean)Oil fromthe comer grocery store.

References:

1. Ferguson, J.; andKemblowski,Z: Applied Fluid Rheology, Elsevier Science Publ. Ltd., 1991, pp

3-8.

2. Marshall, J. A.: Liquidsthat take onlymillisecondsto turn into Solids,Prodeedings of National

Educators Workshop:Update93, pp 315-322.

3. Halsey, T. C.; and Martin, J. E.: Electrorheological Fluids, Scientific American, vol. 269, no. 4,

Oct 1993, pp 58-64.

4. Fergnson, J.; and Kemblowski, Z: Applied Fluid Rheology, Elsevier Science Publ. Ltd., 1991, pp

204-205.

510
CDROM TECHNOLOGY TO STRENGTHEN

MATERIALS EDUCATION

Alfred E. McKenney

and

Evelyn D. McKenney

516 Fairfax Way

Williamsburg, Virginia 23185t

Telephone 804-221-0476

and

Robert Berrettini

Materials Education Council

Materials Research Laboratory

Pennsylvania State University

110 Materials Research Laboratory

University Park, Pennsylvania 16802

Telephone 814-865-1643

511
512
CDROM TECHNOLOGY TO STRENGTHEN MATERIALS EDUCATION

Robert Berrettini, Administrator

Materials Education Council, MRL, University Park, PA 16802

(814) 865-1643

Alfred E. McKenney, Engineer

Evelyn D. McKenney, Instructional Designer

516 Fairfax Way, Williamsburg, VA 23185

(804) 221-0476

• _ j Z:::I:.I:..:.I:I:I:_: :,:•: ]:i:./ _ :, . •

ABSTRACT: It s a material world.:::::_Expe_!_n',en!s_:::a!ld:::_y_e!opments m the engineering

materials scienca_i::i_:_:nol_::_:_i_!_:pi_en)i_i_;at.the National Educator's

_rksh_p_:_::_e:_:!ai_:_::_aiua_t_es_u_e_:::_:_:::._:::_an:i:_i_:_ii!:_ enhanceathe :;.t_teaching

dist_:_:_:_i_:!::_D;_:ROM;:i N_:U!_)?_i]_:b_:_i:::::_Ne: t_ search fo!;_riments by

::iiiitistrations:._gi_g -. -:: CD::ROMtechnology; the NEW:: ex e ents :::::..+:+:+: +: " . :..:: :an 5:::: become a

:::ii:::::_St?rate, reusable laborato_' resource for universi_::i_aeul_i:_an6_:{_achers in

••:::: ::ii_i{_:: :::..::: . s_go[iana . p_g{ . isecondary...... institutions. :_.......:................. .:.:::::::::::::::::: i::ii:_{{{:: ::::: :

PREREQ UIS!i_i_:::X :i.._;:.._i...!..:_i:...:,:.".:: d:i._;.. esire_i_:_::use .::.:.::!:..iiii:.!::...::@ _ {heNEW " Procee_irigs " miii_i;i_ii_}i_{::_! . ::i.::::{:::}: ::::::::::::::::::::::: f_:::?:-:::::_5:1 ::::::::::::::::::::::::::.:h..:." :{ea_]n:_I

•::i_:!_.... " i_ _.. :::: :::: 4:::::::::::

PURPOSE: _::di:_m!ak_:tfi(:National Education Workshop Standard g_im_N i:i:?.i.!+::{:::???)?) !!'ii:::i:i:i :??! i "in

E:n_e_ring Materials; Science an_ Technology more a_¢_S:gib[_i:iofaculty and

stu_en:{s::: using a digitai_::3:?{_:rmai:::io;s_i:ppiem:_ni the _a_i:!_p}_3_:!:i_ok. This digital

form:at_will provide r_ip_d • : .............. access•. to:experiments; ........... incluili_g:::.i_ables ::::: ::::>: and graphics,

througil p0weffui texi::searchingand ihypert_iXtlinking:ii_;:_:eintended media is

CD ROM w_iCh::alt_s _meconOmiCaland thus wider:distribution to the

educational C0mmuntt_i : :

513
THE NEW: UPDATE COMPENDIUM

WHO? The Materials Education Council, in cooperation with the American

Society for Engineering Education will review and select experiments to

be presented in electronic format.

WHAT? 50 Experiments or more will be selected from seven years of NEW

Proceedings.

WHERE? The CD ROM will be produced in participation with Pennsylvania State

University's Materials Research Laboratory which publishes the

Materials Education Council's Jot_rnal of Materials Education, and

other publications and teaching aids.

THE RESOURCE: EIGHT YEARS OF EXPERIMENTS AND DEMONSTRATIONS

The inventory is building.

Participation in NEW:Update Workshops

Attendance at Workshops

1986 1987 1988 1989 1990 1991 1992 1993"

i

45 54 42 82 69 80 67 106"

* These 106 academic participgnts represented 50 separate institutions

Number of Experiments and Demonstrations Published in the NEW:Update Proceedings

Number of Experiments and Demonstrations

1986 1987 1988 1989 1990 1991 1992 1993 Total

* * 16 24 31 32 31 38 172

* Only updates on developments in the materials science field were presented in 1986

and 1987.

514
DIGITIZED TEXT DATA REPRESENTATION, STORAGE and RETRIEVAL

This subject is key to understanding why the soft copy of the NEW Compendium requires

digitized text submission, such as that produced by a word processor. This form of data

enables the most powerful search capability for data retrieval. Digitized text may also be

produced from hard copy by using a scanner equipped with optical character recognition

(OCR) software.

By contrast, a graphic page image can be used to store text and graphics data. In this case, a

scanner is used to capture an entire document page as a grid of black and white pixels. OCR

software is not used. Text, as well as drawings, pictures, and tables are represented as part of

the same page image. Captured this way the text is not machine-readable and therefore not

searchable. Only the whole page can be indexed and accessed. This approach may be useful

where the arrangement of the text on the page is complex, where graphics appear with

regularity, and when the user can find the desired page by means of a key word or

hierarchical index that points to the page image. Graphic page storage also requires

substantially more space than digitized text.

Text data may be structured by an outline for browsing purposes. Users can select chapters,

sections, and headings as convenient access points, provided they know that the material of

interest is located within that part of the text.

Key word searches provide another way of accessing text. Users can find information when

its location is not obvious, or when its occurrence is so frequent that looking though a book

index becomes tedious or impractical. Key terms may be combined to find unique "and",

"or", and "not" related documents.

Besides the above search methods, the software to be used in the Compendium CD-ROM will

provide hypertext capability. Hypenext describes different ways of linking related items to

each other. In its simplest form, know as "sideways browsing," the user selects a displayed

word or phrase and with a single keystroke finds all documents that contain that word or

phrase. It is possible to search for related terms as well, or provide for item linking created by

the publisher or user. "Fuzzy logic" searching is also provided. This permits detection of

"near hits" and ranking by probability of value of the hits.

Graphics, which includes pictures, charts, illustrations, and formulas, will be searched in the

Compendium by means of indexed captions.

The user may make soft copy "notes" as review of the material proceeds, for later use.

In digitized form, including the essential graphics charts and pictures, the Compendium will

take an estimated 1/6 of a CD-ROM's capacity. This will leave adequate space for expansion

in future years and for additional still and motion video.

515
PROJECT ACTIVITIES REQUIRED to PRODUCE the COMPENDIUM CD-ROM

SET UP

A project management system will be set up for reporting activity and

maintaining essential files.

USER NEEDS

"Users" are the ultimate beneficiaries of this project. Faculty who have been

active in the workshops and in use of the proceedings will be consulted prior to

drafting specifications for the end product, insofar as these requirements can be

achieved in this initial issue. Some requests may be set aside for future

consideration. By the end of this activity, agreement will be reached on the

experiments to be included in the compendium; specifications for searching,

reading, and using the information; and the platform(s) for this initial issue.

SOFTCOPY BOOK DESIGN

A style sheet will be prepared that reflects the user specifications for searching,

reading, and using information. A production guideline will be prepared

outlining the sequence and procedures for data preparation and digitizing. The

guideline will accommodate the different types of documents, including tables,

graphics, photographic images, etc. The guideline will include quality control

processes to ensure accuracy of the final product.

TEXT and GRAPHICS ENTRY

The difficults_ of producing the compendium will be eased by obtaining

electronic files of documents from their presenters, where they exist. However,

we anticipate that initially some of the text and graphics content will not be

found in digital form. Many documents and images will need to be scanned

using optical character recognition (OCR) and graphics software. Student

interns will check for errors in text scanning and pay meticulous attention to

formulae. Formulae may be treated as scanned text or as graphics, whichever

may best suit user needs.

Final text must be in one of the following formats: WP5.0 or 5.1, WP for Win

5.1 or MS Word for Win 2.0.

A log will be kept of all activity, including "lessons learned" and recommendations made for document style and format submitted in future Proceedings.

516
?roject Activities continued)

BUILDANDTEST

The components of each experiment - text, tables, graphics, and images will be

formatted in accordance with the previously defined style sheet. The

compendium will be indexed and compiled using the IBM BookManager

software.

Once compiled, the compendium can be tested while it resides on the hard

disk. A developer's test will ensure that the book operates as expected. Test

copies will be produced and distributed on 3.5" disks for loading on testers'

hard drives. Selected users will then search, read, display, print and copy the

information as it is intended to be used by faculty and students. When revisions

are complete, the master file will be transferred to a "one-off" single CD ROM

for final testing.

PRODUCE AND DISTRIBUTE

A vendor will be selected for production - stamping the discs, imprinting with

art work, inserting into the familiar "jewel" box and sealing for distribution.

Distribution of the CD ROM will be on an "at cost" basis to NEW:Update

attendees, interested faculty, teachers and media centers of educational

institutions.

The IBM BookManager DOS/Windows/OS/2 Read module will be included on

the Compendium CD-ROM.

EVALUATION

Formative and summative evaluation will ensure acceptance of the initial issue

and provide recommendations for future editions of the Compendium.

SUBMISSION GUIDELINES

Based upon experience with this first CD-ROM, a guide will be prepared to

supplement the existing Call for Papers standards where changes would

facilitate both hard copy printing and soft copy production.

RELEASE DATE

Project funding for the CD ROM has been requested from the National Science

Foundation. Summer '95 is the anticipated release date if funding is granted.

517
POTENTIAL IMPACT

THE EXPERIMENTS

Each experiment that is submitted for presentation at the Workshops is

subjected to peer review prior to acceptance. During presentation at the

Workshop, experiments are critiqued on site and also videotaped for review by

the author or other participants. This acceptance process ensures it's value as a

laboratory resource.

LABORATORY RESOURCE

In their present form, the experiments are proving their value to faculty who

have adopted them for instruction. The Compendium on CD ROM will widen

this audience and provide the materials education community with current,

valuable aids for teaching and research in a format that can be readily searched,

retrieved, and edited. It is expected that the experiments will find their way

into the laboratories of educators at every level.

NETWORKED RESOURCE

Once installed in a CD ROM tower at a media center, the Compendium on CD

ROM can be accessed through local and wide area networks.

COMPENDIUM PROGENY

Some experiments will have added value when presented with video,

animation, and interactive content. Future issues of the Compendium may

include multimedia presentations.

This experience will allow the publication of a guide for submitting future

experiments and demonstrations to provide efficient and rapid dissemination.

A production guide for faculty interested in developing similar materials in

digital form will be a product of the lessons learned in producing this f'trst CD

ROM.

518
A COMPARISON of ESTIMATED PRINTING and CD-ROM PRODUCTION COSTS

This is for a quantity of 400 NEW Update93 Proceedings. The cost excludes one time costs,

data preparation, editing and authoring costs.

HARD COPY

PRINTING & BINDING $9,600 Unit Cost $24

SHIPPING $ 3

CD-ROM

PRODUCTION & PACKAGING $3,200 Unit Cost $ 8

SHIPPING $ 1.50

THE FEDERAL GOVERNMENT is a LEADER in EFFICIENT DATA STORAGE,

DISTRIBUTION and RETRIEVAL THROUGH the USE of CD-ROM TECHNOLOGY

On November 18, 1993, OPNAV Instruction 5230 was issued. This instruction establishes

CD-ROM technology as "the preferred media for storage and dissemination of data and

information" for the Navy and Marine Corps.

All other major agencies are actively engaged in the production of CD-ROMS in order to

increase efficiency of storage and distribution of data. Some examples:

The Government Printing Office publishes the massive USCode on one CD--ROM for $30.

The US Coast and Geodetic Survey (USCGS), a leader in the field, publishes geographic data

on CD-ROMs for industry and the public. The USCGS has took the lead in 1986 by

establishing a Special Interest Group on CD-ROM Applications & Technology (SIGCAT).

This group has sponsored many studies on the technology and applications and participated in

international standards setting. Meetings open to the public and government agencies are held

every two months around the country, often in the Washington Metropolitan Area.

The Department of Agriculture is using CD-ROMs to preserve irreplaceable old archived

documents which are disintegrating. In this case, graphic page storage is used to preserve the

many tables, figures and illustrations contained in the documents.

END of PAPER

519
520
521
ABOUT the AUTHORS

Robert Berrettini has served for the past 14 years as administrator of the Materials Education

Council and managing editor of the Journal of Materials Education. He has been directly

involved in the development of video taped courses and teleconferences, and a variety of

teaching aids in materials science ad engineering. He also currently serves as adjunct

Assistant Professor in the Science, Technology and Society Program at Penn State. He

received his B.A. (sociology) from Shippensburg University, M.S.Ed. from Wilkes University

and D.Ed. from Penn State.

Alfred E. McKenney, a NEW Workshop participant since 1988, was a systems designer with

IBM until he was assigned by IBM on its faculty loan program, to the School of Technology,

Norfolk State University. At NSU he joined Dr. James Jacobs in a successful effort to fund

and establish the School's Technology Education Learning Lab. This lab was a 20 station

networked facility with CD-ROM, interactive videodisc, and video capture capabilities for

multimedia development. Mr. McKenney instructed educators of all levels in the use of

commercially available experiments programs such as the IBM Personal Science Laboratory,

and in the production of their own materials. Mr. McKenney received his B.S. (engineering)

from the United States Coast Guard Academy and his MBA from Harvard Business School.

Evelyn David McKenney, has ten years experience in interactive videodisc instructional

design and production - for industrial training. She supervised a development lab responsible

for converting 60 videodiscs from their original barcoded format to run on SONY, JVC, IBM,

VISAGE, and ITS platforms. She has worked with UNIX, Apple, and DOS operating '

systems. As a senior consultant to Boeing Computer Services she designed and supervised

their RCAS award winning prototype, an Open Systems Computer Based Training module for

delivery at the desktop. The course was developed and delivered in an Open Systems, Xwindows, SCO-UNIX networked environment. Ms. McKenney received her B.A. (design)

from Antioch College and her M.Ed. from Harvard Univeisity.

522
/

OSHA A93-2 \

REGtSTRATION

q/otmat*on t,n luture OSHA CO.ROMs, please out the February 1993 "'-""_1

qecj4strahol; Form. [f you reqlstered previously, you do not need to d(: _: . ,:,_,. ,,_la,n. When completed, send to: U.S. Oepartment of Labor, OSHA

:,D.ROM Reg=s{rauon, PO Box 65200. Salt Lake City. UT 84165. ' ,..i

- _r!lI:all, !

_,,cDar(rllelll

_rllaCl P_tSorl

_JJress

t_{i,.'e lv,.e IGIIC ,,itl{_ £:ottlr'MetltslsLIg(Jestlolls:

523

EFFECT OF RISERS ON CAST ALUMINUM PLATES

H. T. McClelland

2103 14th Avenue, E.

Menomonie, Wisconsin 54751

Telephone 715-232-9597

525
526
EFFECT OF RISERS ON CAST ALUMINUM PLATES

by

H. T. McClelland

Technology Department

University of Wisconsin--Stout

Menomonie, WI 54751

KEY WORDS: Casting, risers, gating systems.

PREREQUISITE KNOWLEDGE: This experiment is intended for an

introductory casting class. The students should have been

exposed to the concepts of solidification shrinkage and risers in

class.

OBJECTIVES: To demonstrate the solidification shrinkage of

metal and common methods of producing a good cast part. To

demonstrate the casting of a plate with no riser, a small riser,

a medium riser, a large riser, and the effects of feeding

distance.

EQUIPMENT AND SUPPLIES: To perform this experiment with

aluminum or copper, a furnace capable of melting these metals is

required. Crucibles, patterns, green sand or oil sand, flasks,

and mold making tools are needed. A well ventilated area is

recommended.

BACKGROUND Cast metal parts shrink in three stages: when

cooling from the pouring temperature to the solidification

temperature, during solidification, and from the solidification

temperature to room temperature. The pattern maker makes the

pattern oversize to compensate for the solid shrinkage but the

gating system must compensate for the liquid shrinkage. In some

cases, the runner system provides enough liquid mass but, in many

cases, a riser is needed to compensate for the liquid shrinkage.

A riser is a liquid reservoir closely connected to the casting

and which is designed to be the last part of the system to

freeze.

PROCEDURE: The kidney shaped pattern used for this

experiment at Stout is shown in Figures 1 and 2 but any platelike shape of the same approximate dimensions could be used. The

pattern contains a draft (taper) on the sides so it could be

removed from the mold after ramming. A small hole in the middle

of the top of the pattern was used with a screw to help remove

the pattern from the mold.

Eight mold configurations are used:

i. Gating into the middle of the plate with no riser,

2. Gating into the end of the plate with no riser,

3,4. Gating into the same locations using risers

approximately 38 mm (1.5 inches) in diameter and 38 mm (1.5

inches) high.

5,6. The same gating locations using risers

527
approximately 47.6 mm (1.87 inches) in diameter and 51 mm (2 in)

high,

7,8. Gating from the same locations using risers

approximately 63.5 mm (2.5 in) in diameter and 63.5 mm (2.5 in)

high.

The riser patterns are shown in Figure 3. The risers should

be placed as close to the plates as possible allowing for

relatively easy removal. Riser bulbs were cut by hand under the

patterns.

After the molds were made and vented, they were moved to a

proper pouring area near the melting furnace. Weights were

placed on top of the molds to prevent the cope from floating and

a runout occurring. The aluminum was poured in two melts at

680°C (1250°F). Once the castings solidified and cooled, they

were shaken out.

ANALYSIS OF THE RESULTS: The amount of shrinkage was

observed as a function of the presence and location of the

risers. There was no shrinkage with the medium or largest risers

when the gates were properly made as shown in Figures 4. It can

be seen that the medium riser contains a shrinkage cavity

indicating proper feeding. The large riser had a small hole on

the far side and the shrinkage occurred internally. Figure 5

contains an example of the casting with a small riser with severe

shrinkage on the bottom. Figure 6 contains an example of the

casting with no riser, again with bottom shrinkage. Figure 7

contains a casting from another class with no riser demonstrating

top shrinkage.

The importance of a proper gating system is shown in Figures

8 and 9. Figure 8 contains an example of a casting with a medium

riser where the gate was not completely open. Figure 9 contains

a similar example for a casting with a large riser.

Figure i0 contains a summary of the types of shrinkage

observed in the other cases. At gate location 1 with no risers,

a large shrink cavity was generally observed as shown by location

"a" and was often at the bottom of the part. The shrinkage is at

the bottom of the part when the hottest metal enters the part

along the bottom and the top freezes first. Shrinkage from a

gate at location 2 with no risers was generally at locations "b".

Again, these are often at the bottom of the part.

The medium riser size is a borderline situation. If the

gate into the riser and the riser connection are large enough

coupled with a somewhat hotter pour, there was no shrinkage.

Otherwise, smaller amounts of shrinkage occurred at "c" or "b"

The smallest risers were not adequate to feed without some

shrinkage occurring and the castings with no risers had increased

shrinkage.

It should be noted that modifications of the gating system

may cause the hotter metal to flow along the top and the

resulting shrinkage to occur there. Changes to a more simple

plate-like shape may also change the location of the shrinkage.

The final observation was the relative amount of good

casting versus the total amount of metal poured. The gating

528
systems were removed and weighed, the cast parts were weighed,

and relative amounts calculated:

% yield = i00 x (wt. of part/total wt. of part and gating

system)

The major decrease in yield as risers were added are shown in the

table:

Configuration Yield

No risers 49%

Smallest riser 41%

Medium riser 40%

Largest riser 31%

The best configuration is the one with the smallest gating

system that produces consistently good parts which, in this case,

is the medium riser configuration.

SAFETY CONSIDERATIONS: The use of high temperatures and the

presence of molten metal make safety a major consideration.

Melting should be done in a well ventilated area. All furnace

charge material should be dry and clean; this is particularly

important for all metal added to the molten metal or a steam

explosion may occur.

All personnel directly involved in pouring should wear

protective clothing including face shields. All others should

stay well clear of the pouring area in case a mold blows back.

The castings should be allowed to cool completely after

pouring to avoid burns. Overnight cooling will guarantee to

castings are cool enough to handle. If the castings are shaken

out before they are completely cool, they should be handled with

tongs and quenched until cool.

INSTRUCTOR'S NOTES: The instructor should demonstrate mold

making using the type of mold material available before beginning

to melt the metal, possibly in a previous class period. The

students can then make their molds while the metal is melting

with each student or group of students using a different mold

configuration. A normal class size at Stout is about 25 students

using eight molding stations. This allows some duplication in

mold configurations. There are usually two sections on

consecutive days so two replicates of each configuration are

made.

A second demonstration may occur at this time if there are

enough molds compared to the amount of metal melted to require a

second crucible of metal. The first pour can be made at the

recommended pouring temperature (approximately 680°C (1250° F)

529
for aluminum) and the second pour can be made considerably hotter

(approximately 780oC (1400OF)). The lower temperature pour

should result in a relatively smooth surface while the hotter

poured surface should be much rougher due to the hotter, more

fluid metal seeping between the sand grains.

The size of the required riser can be approximately

calculated using a number of techniques. For the current

configuration, calculations were made using the modulus method:

M = V/S where M is the modulus, V is the volume, and s is

the surface area.

The modulus of the riser should be at least 10% greater than

that of the casting to ensure that the riser freezes last. The

volume of the casting, in this case, was approximated as a

rectangular plate 130 mm x 78 mm x 18 mm (5 in x 3 in x 0.75 in).

For the sake of easier calculations, a domed cylinder with a

height equal to the diameter was considered.

V = 130(78) (18) = 182520 mm3

S = 2(130) (78) + 2(78) (18) + 2(18) (130) = 25896 mm2

Mc = V/S = 182520/25896 = 7.05

Assume the riser modulus to be 10% greater

Mr = 1.1(7.05) = 7.76

Assume the riser is a domed cylinder

Vr = _(D2 /4)H + (I/6)_D3

Sr = _DH + _D2

Assume D = H

Mr = ((_/4)D3 + (_/6)D3 ) / 2_D2

Mr = 0.208D = 7.76

D = 37.3 mrd_ 1.47 in

The calculations gave a riser diameter of approximately 37.3

mm (1.5 inches). An abbreviated method shown in reference 1 for

a truncated cone results in the same'value. This would indicate

that the small riser should be sufficient. Closer agreement

could possibly be obtained by calculating the true volume and

area but would still be approximate since various alloys can be

expected to react somewhat differently. These calculations are

generally considered to be used as a guide and serve to reduce

the amount of trial and error needed.

REFERENCES;

i. American Foundrymen's Society Cast Metals Institute,

Basic Principles of Gating and Risering, 1973, AFS, Inc, Des

Plaines, IL, 60016-8399.

The tables containing the riser equations are contained

in an accompanying Gating Worksheets document, page 24.

2. LaRue, J.P.,.Basic Metalcasting, American Foundrymen's

Society, Inc., Des Plaines, IL. 60016-2277, 1989.

This is a very good introductory text on the techniques

of making castings including safety precautions.

53O
_" 130 mm -"

25 mm rad

_ 78 mm 1 j\ 50mm il i

! \

- t 2

13 mm "---i /

TOP VlEW

Figure I: Top view of sample part showing riser locations.

_78mm "---"% _

/--_ / \

I _ I \ /

';2 /

/ / \ /

18ram /2 ,'I_ I

<..._.. <....J , ¢, U

FRONT VIEW

Figure 2:

Figure 2: Front view of sample part showing riser

locations.

531
Figure 3. The patterns for the small, medium, and large

risers are shown. The tape measure is in inches.

Figure 4. Successful end fed castings with a medium riser

showing the shrinkage cavity in the riser) and a large riser.

Figure 5. An end fed unsuccessful casting with a small

rlser and having bottom shrinkage.

532
Figure 6. An unsuccessful casting with no riser and bottom

shrinkage.

Figure 7. An end fed and a center fed casting with no

risers and containing top shrinkage.

Figure 8. An unsuccessful casting using a medium riser and

containing bottom shrinkage. The riser connection was not

completely open and froze prematurely.

533
Figure 9. A incomplete casting with a large riser. This

shrinkage was also due to the riser connection prematurely

freezing.

' i

...._..... ..... _ .... .2___- I

1 a C

/-

j,../

I I

SHRINKAGE TOPVIEW

Figure i0: Schematic top view of part showing shrinkage

locations.

534
EMERGING MATERIALS TECHNOLOGY

Harris M. Burte

Chief Scientist

WL/ML

Air Force Materials Laboratory

Wright Patterson Air Force Base

Ohio 45433-7734

Telephone 513-255-2738

535
536
EMERGING MATERIALS TECHNOLOGY 

HARRIS M. BURTE 

CHIEF SCIENTIST, AIR FORCE MATERIALS LAB 

MATERIALS SHAPE THE FORM OF CIVILIZATIONS 

MATERIALS ARE THE STUFF FROM WHICH THINGS ARE MADE 

MOST INDUSTRIAL NATIONS HAVE TARGETED MATERIALS TECHNOLOGY 

AS ESSENTIAL TO ECONOMIC DEVELOPMENT AND COMPETITIVENESS 
"MATERIALS SHAPE THE FORMS OF CIVILIZATIONS", 

"INNOVATION IN MATERIALS HAS BEEN RESPONSIBLE FOR #ORE MAJOR TECHNOLOGICAL 

ADVANCES IN THE LAST 50 YEARS THAN I S GENERALLY RECOGNIZED, MATERIALS 

TECHNOLOGY IS TRULY AIJ ENABLING TECHNOLOGY, FURTHERMORE THERE IS NO SIGN 

THAT THE SOURCE OF INNOVATION IS DRYING UPN, 

"ADVANCED MATERIALS WILL BE THE RATE DETERMINING STEP IN THE INTRODUCTION 

OF TOMORROW'S NEW TECHNOLOG IES AND INDUSTRIES", 

WORKING GROUP ON TECHNOLOGY, GROWTH 

AND EMPLOYMENT-VERSAILLES ECONOMIC 

SUMMIT, 1982 
THE GROWTH AND ACTIVITY OF A WORLDWIDE MATERIALS SCIENCE COMMUNITY IS 

YIELDING A CORNUCOPIA OF POSSIBILITIES FOR NEW MATERIALS AND PROCESSES 

THE PURSUIT OF THESE INTO TECHNOLOGY HAS LED TO SOME OUTSTANDING 

SUCCESSES - BUT ALSO SEVERAL EXAMPLES OF BIlTER DISAPPOINTMENT OR EVEN 

BANKRUPTCY 

LET US BOTH LOOK AT THE CORNUCOPIA AND EXPLORE HOW WE MAY MAXIMIZE THE 

POTENTIAL AND AVOID THE PITFALLS OF EMERGING MATERIALS TECHNOLOGY 
STERlOSPEClFlC POLY MERlZATlON 

RAPID SOLIDIFICATION 

MOLECULAR BEAM EPITAXY 

PULSED LASER DEPOSITION 

THE CORNUCOPIA 

ADVANCED COMPOSITES 

- POLYMER MATRIX 

- METAL MATRIX 

- CERAMIC MATRIX 

- CARBON CARBON 

SUPERLATTICES 

MOLECULAR COMPOSITES 

DIAMOND COATINGS 

NONLINEAR OPTICAL MATERIALS 

CONDUCTING POLYMERS 
CONSIDER THE COMPETITION 

THE DEVELOPMENT OF OXIDE-DISPERSION-STRENGTHENED ALLOYS IN THE 1950s AND 1960s WAS 

A METALLURGICAL BREAKTHROUGH. ALUMINUM AND NICKEL COULD BE ENDOWED WlTH USABLE 

STRENGTH UP TO 90% OF THEIR MELTING POINTS INSTEAD OF THE FORMER TEXTBOOK LIMIT OF 

ABOUT 60%. YET THE DEVELOPMENT OF OXIDE-DISPERSIONSTRENGTHENED ALLOYED PRODUCTS 

(E.G., SINTERED ALUMINUM POWDER) WAS NOT COMPETITIVE WlTH NEW TITANIUM ALLOYS. 

SINTERED ALUMINUM POWDER AND RELATED PRODUCTS SOON WENT OUT OF PRODUCTION. 

DISPERSION-STRENGTHENED NICKEL WAS PERHAPS THE MOST SUCCESSFUL OF THE GROUP BUT 

NOT SUFFICIENTLY SO TO PREVENT SERIOUS FINANCIAL LOSS TO SOME OF ITS EARLY PROPONENTS. 

NOT ONLY DID COMPETITION EMERGE FROM OTHER APPROACHES TO HIGH-TEMPERATURE STRENGTH 

IN NICKEL-BASE ALLOYS, BUT IMPROVED DESIGNS FOR COOLING MADE THE ALLOYS' CAPACITY TO 

BE SHAPED INTO COMPLEX CONFIGURATIONS AS IMPORTANT AS STRENGTH. COMPETITION IS A 

FUNDAMENTAL RISK. 
REN 400 - A 

-, ALUMINUM 

E 41 (A) 

S.A. P. 

I I LA-. - - I I 

209 400 609 839 1390 1200 

TEMPERATURE (OF) 
POLYMER MATRIX COMPOSITES 

THE DEVELOPMENT OF POLYMER MATRIX COMPOSITES AND THE TRANSITION TO THEIR USE HAS 

BEEN ONE OF THE MORE EXCITING CHAPTERS OF MODERN MATERIALS TECHNOLOGY-BUT THERE 

HAVE BEEN PITFALLS. ROLLS ROYCE, IN COMMITTING ITSELF TO A JET ENGINE USING FAN BLADES 

MADE OF CARBON FIBER-EPOXY MATRIX COMPOSITE, DID NOT ADEQUATELY CONSIDER OR 

EVALUATE THE EROSION OR IMPACT-RESISTANT QUALITIES OF THE MATERIALS AND DESIGNS 

THEY WERE USING. BEFORE THE COMPANY COULD SOLVE THE PROBLEM, THIS OVERSIGHT LED 

TO ITS BANKRUPTCY. 
WROUGHT TITANIUM 

WROUGHT TITANIUM FOR USE IN JET ENGINES WAS A COMPARABLE DEVELOPMENT THAT 

PRECEDED THE ROLLS ROYCE EFFORT. SHORTLY AFTER ITS INTRODUCTION, A SERIES OF 

SERVICE FAILURES THREATENED ITS CONTINUED USE, BUT IN THlS CASE, A STRONG 

TECHNOLOGY BASE RESEARCH GROUP WAS EXPLORING SOME UNUSUAL BEHAVIOR IN 

TITANIUM, INCLUDING THE DETRIMENTAL EFFECTS OF HYDROGEN. THlS RESEARCH GROUP 

HAD THE BACKGROUND AND EXPERIMENTAL CAPABILITIES TO STUDY THE FAILURES AND 

QUICKLY REALIZED THAT SLOW STRAIN-RATE HYDROGEN EMBRITTLEMENT, WHICH WAS 

KNOWN TO OCCUR IN'STEEL, COULD ALSO OCCUR IN CERTAIN TITANIUM ALLOYS. THE 

RESEARCH GROUP WAS ABLE TO PROVIDE SOLUTIONS TO ENSURE THE CONTINUED 

EFFECTIVE USE OF TITANIUM. 
l5ummEs 

DENS I TY 

PLASTIC HODUL I

STRENGTH 

DIELECTRIC COIJST . PERMEAB I L I TY 

Loss FACTOR 

PROCESS 4 STRUCTURE* PROPERTIES 

DENS 1 TY 

PLASTI c MODUL 1 

STRENGTH 

0 I ELECTRIC Corrc T . Loss FACTOR 

Syms - -RE - PRI)PERTIES - u3k 

MILLING TIME COMPOS 1 T ION DENS I TY BLADE 

PPESSED ~ENS~TY PHASES PLASTIC MODULI COM@USTOP 

FlRltl~ TIME MICROSTRUCTURE STRENGTH HEAT ExcI~I.'I..I. 

FIRI:,; I\TMOS. Dl ELECTR IC CONST. EEAR I NG 

FI~:,IG TEMP. Loss FACTOR RADC:.'~ 
WHAT DO WE KNOW? 

MICROSTRUCTURE - PROPERTY 

HOW DO DIFFERENT CHEMISTRIESIMICROSTRUCTURES 

INFLUENCE PROPERTIES? 

PROCESSING - PROPERTY 

CAN WE SYNTHESIZE THE DESIRED MICROSTRUCTURE? 

UNIFORMLY AND REPRODUCIBLY? 

CAN WE MODEL THE PROCESS TO GUIDE SCALE-UP? 

PROPERTY-USE 

WHAT PROPERTIES MEASURED IN THE LABORATORY WILL 

PREDICT BEHAVIOR IN SERVICE? 
PROCESSING 

A KEY ASPECT OF SUCCESSFUL TECHNOLOGY INVOLVES ROBUST PROCESSING -THE COST OF MAKING THE MATERIAL 

AND SHAPING IT INTO THINGS WE USE AND THE UNIFORMITY AND REPRODUCIBILITY OF THESE THINGS. THE EVOLUTION 

OF COMPUTATIONAL PLENTY IN THE LAST TWO DECADES NOW ENABLES US TO AlTAlN ADEQUATELY ELEGANT SOLUTlONS 

TO PREVIOUSLY INTRACTABLE SETS OF EQUATIONS WHICH DESCRIBE A PROCESS SUCH AS FORGING. THE 

MODELING AND COMPUTER SIMULATION OF THESE PROCESSES ALLOWS US TO DESIGN THEM QUICKLY AND RELIABLY, 

TO SCALE THEM AND TO CONTROL THEM. AN EXAMPLE TO BE GIVEN, OF NON-ISOTHERMAL FORGING OF A STEEL BILLET, 

WAS ACCOMPLISHED AS HIS SENIOR COLLEGE THESIS BY MY YOUNGEST SON. I SHOW IT NOT ONLY AS A PROUD FATHER, 

BUT MORE IMPORTANT TO MAKE THE POINT THAT AN INCREASING NUMBER OF YOUNG ENGINEERS ARE BEING GRADUATED 

WHO ARE FAMILIAR AND COMFORTABLE WITH THE SCIENCE AND TECHNOLOGY OF MODELING UNIT OPERATIONS 

AND UNIT PROCESSES. INDUSTRY WHICH LEARNS TO USE THEM WILL PROSPER IN A COMPETITIVE WORLD. THE CHEMICAL 

ENGINEERS HAVE DONE THIS FOR DECADES; IT IS RAPIDLY EXTENDING TO MANY OTHER FIELDS AND PROCESSES. EVEN 

WHERE THE PROCESSES ARE TOO COMPLEX FOR NUMERICAL SIMULATION - AS IN OUR CURRENT INABILITY TO FULLY MODEL 

THE MANY PROCESSES OCCURIE!G IN AUTOCLAVE CURING OF COMPOSITES - A QUALITATIVE MODEL CAN EE DEVELOPED 

USING THEORETICAL OR EMPIRICAL KNOWLEDGE. THIS CAN BE EXPRESSED AS A SET OF RULES AS IN AN EXPERT 

SYSTEM OR OTHER ARTIFICIAL INTELLIGENCE BASED APPROACHES, WHICH BECOMES THE BASIS FOR MUCH IMPROVED 

CONTROL SYSTEMS. 
DUAL PROPERTY TI-6242 DlSK 

PROPERTIES t-----' MICROSTRUCTURE - POTENTIAL WINDOWS 

- BORE 

TENSILE STRENGTH 180 KSI SMALL ENGINE (HIGH RPM) DlSK 

FRACTUR:TOUGHNESS 70 KSI IN. HIGH PERFORMANCE LARGE GAS 

LOW CYCLE FATIGUE 10IN1lOOKSI TURBINE ENGINE DlSK 

1750Fl1750FIAC 

ALPHA + BETA PROCESSED MICROSTRUCTURE 

- RIM 

CREEP PROPERTIES 95 KSU.2°/~1120 HRS. 

FRACTURE TOUGHNESS 70 KSI IN 

21 00Fl1840FlAC 

WIDMANSTATTEN MICROSTRUCTURE 
ROBUST CHARACTERIZATION AND DESIGN 

INCREASINGLY, IN OUR TECHNOLOGICAL CIVILIZATION, WE ARE USING MATERIALS CLOSER TO 

THEIR LIMITS (TO ACHIEVE PERFORMANCE), AND THE CONSEQUENCES OF FAILURE ARE MORE 

CATASTROPHIC. THIS MAY NOT BE A NEW PROBLEM, BUT IT CERTAINLY TAKES ON ADDED 

IMPORTANCE WHEN THE VIABILITY OF AN ENTIRE INDUSTRY OR APPROACH TO SOLVING 

HUMANITY'S NEEDS - SUCH AS NUCLEAR POWER - DEPENDS ON HOW WE COPE WITH IT. NEW 

SCIENCE AND TECHNOLOGY, SUCH AS LIFE PREDICTION AND NONDESTRUCTIVE INSPECTION 

CAN ALLOW US TO ACHIEVE PERFORMANCE, EXTEND LlFElREDUCE COST AND RETAIN 

RELIABILITY. 
PROBABILITY OF REJECTION

CRITICAL FLAW

SIZE

FA/

55O
PERFORMANCE MODELS

RELIABILITY B MAINTAINABILITY ANALYSIS

LOGISTICS ANALYSIS

OFF_ oPERFORMANCE

I oPRODUCIBILITY

DESIGNTRADE- oRELIABILITY

oSUPPORTABILITY

o ETC.

MANNING/TRAININGANALYSIS

MANUFACTURINMODE G LS

OPTIMIZATIONRULES/ INTEGRATIONEXPE.RT

PERFORMANCE(CAD]

WEB

MANUFACTURE |CAM|

b.

BORE

SUPPORTABILITY |CASI

€.

551

ASM EDUCATIONAL TOOLS NOW AND

INTO THE FUTURE

Robert Uhl

Director of New Services Development

ASM International

St. Rt. 81

Materials Park, Ohio 44073

Telephone 216-338-5151

553
554
INFORMATION DELIVERY MOOES

APPROPRIATE TO THE LIFE SPAN OF TECHNOLOGY

I::;ectronicNetworks

"Seminam/Conferences

Journals

Magazines

Oflline D-ar'aJ_asse

Te,c_lk=]lBoolm

How-toManuals

Handbooks/GeneralReferenceBooks

Stable MEl/Video

"11_modes

555
Longer-Term View: Holder of information will have

power. What will the long-term hold for us "as users"

can connect directly into databases? How do we

position ourselves for the long-term ...

• Quality

• Quantity

• Structured

• Expert Systems (searchable)

• Consolidated

• More Searchable

• Ranking of Attributes

RCU4/jld/mkt2

556
"AN ELECTRONIC FUTURE"

Concept/IssuesPlanningDocument

INFORMATION USERS

Individuals

• Research • Students

• Engineers • Technicians

• UniversityLibraries

• Corporate h'braries

• Research Laboratories

• Non-North American

• Non-EnglishReading

,• CAD/CAM Producers

• Training Schools

• Universities

• Trade Associations/Societies

• Corporate Trainers

557
"AN ELECTRONIC FUTURE"

Concept/Issues Planning Document

PRODUCTS/SERVICES

• Traditional Book

• Segmented Print Product (print-on-demand)

• Committee/staff-selected • Customer online selection

• Online review of material/download

• Online/Electronic Product Search Engine (Tool)

• Word, phrase, association, thesaurus, numerical values (properties), greater

than/less than, etc. "

• Expert System (online interface PC product, work station, LAN)

• Information Availability on Common Software (Lotus, Excel, etc.)

# CD-ROM

• PC/LAN • download & print feature

• single/multi-user

• Images

# Video

• AudioTapes

• BulletinBoards

• SegmentsofDatabase as ElectronicDatabaseProducts

• Selectionas SegmentedPrint Product

• Usage Issuessuchas for CD-ROM

• InformationCentral(complexvision- multi-usage)

558
"AN ELECTRONIC FUTURE"

Concept/Issues Planning Document

DATABASE ARCHITECTURAL/BUSINESS ISSUES

• Online Purchase/Billing for Print-On-Demand Products

• Royalties on Online Downloads/Online Billing

• Online/Electronic Product Search Engines (Tools)

• Expert System (online interface, PC product, work station, LAN)

• Source of Material Information and Tracking (References -- original & last)

* Tagging System

• File Control

• In-house/out-house • Maintenance

• Security • Copyright notices

• Establishing updating programs on

subscription products in electronic format

• PC Download Online

• CD-ROM Royalties

i

• PC-Based Product

• Networks

• Site licenses

• Ability to Work Across Platforms

• Multimedia

• Database Contents

* Text • Images

• Properties • Audio

• Graphs • Video

• Artwork

• Bulletin Boards

559
Digital Info of Any Type on a Single Disc 

Mainframe Computer 

Database 

---.-.-- Electronic 

Publishing 

Scanned Text 

Graphics 

Audio 

Video L 

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570
DENSITY BY TITRATION

Raymond Bruzan

Science Department Chair

Lanphier High School

Springfield, Illinois 62702

Telephone 217-525-3080

and

DouglasBaker

SpringfieldPlastics,Inc.

Auburn,Illinois62615

571
Density By Titration

Raymond Bruzanl

ScienceDepartmentChair

Lanphier High School

Springfield, Illinois 62702

and

Douglas Baker

Springfield Plastics, Inc.

Aubum, Illinois 62615

Key Words: Polymers, density, polypropylene, titration, volumetric analysis, miscible,

buret, displacement, percentage of error.

Prerequisite Knowledge: The student should have an understanding of the concept of

density and be familiar with density calculations that involve data experimentally collected.

Students should be given instructions on how to properly prepare and read a buret.

Objectives: 1) To better understand the concept of density. 2) To acquire volumetric

analysis laboratory techniques and apply them to the determination of the density of

polypropylene by titration and displacement.

Equipment and Supplies:

1. two 50 mL burets

2. buret clamp and stand

3. distilled water

4. ethanol

5. two 100mLbeakers

6. balance

7. Bic round stic ® pen

Introduction:

Density is one of the decidingfactors of a material's usefulness and selectionfor application.

The concept of distinguishing between low-density and high-density polyethylene presented by

Kolb2led to the development of this density lab involvingvolumetric analysis. Often called the

flotation method, this proceduremay be used to determine the density of a_solid that is

insoluble in two miscible liquids of different densities.3

The plastic barrel of a Bic4round stic® pen serves as the solid. It is composed of

polypropylene and containsthe pigment titanium dioxide,TiO2.The density of the plastic, as

572
reported by the Bic@ Corporation, is .903 g/mL and must fall between the densities of the two

liquids. Ethanol and water thus serve as suitable liquids.

Using titration, the end point is reached when a solution of the two liquids has a density

equivalent to the plastic of the barrel. At this point, the plastic just becomes buoyant. The

solution's mass and density can be calculated since the solution volume and volumes of both

liquids at the end point of titration are known. The following procedure, previously described

in the Journal of Chemical Education (1993, Vol. 70, p. 397), is used to determine density of

the two liquids. Density of the plastic barrel is then determined utilizing titration and ethanol

displacement. Sample data and calculated results are provided in the table.

Procedure A - Density of Ethanol and Water

1. Fill two 50 mL burets, one with distilled water and one with ethanol.

2. Label two 100 mL beakers, #1 and #2.

3. Mass beaker #1 and run 15.00mL of ethanol into it from the buret.

4. Mass the beaker and ethanol. Save this for Procedure B.

5. Repeat the above procedure using water and beaker #2. Save this for Procedure B.

Procedure B - Density of Plastic by Titration

1. Remove and discard from the barrel the inside ink cartridge and the end caps of a Bic round

stic® pen.

2. Use a sharp blade with caution to cut offtwo 3-4 mm pieces of the barrel. Save the

remainder of the barrel for Procedure C.

3. Drop one piece into each of the two beakers containing liquidsfromProcedure A.

4. Observe evidence that the plastic's density is greater thanethanol but less than water (See

the figure).

5. Place beaker #1, containing ethanol and plastic, under the buret withwater. While stirring

vigorously, titrate with water until theplastic just becomes buoyant (See the figure).

6. Record thevolume of water required to reach the end point.

7. Remove the plastic carefullyfrom the solutionand use a graduated cylinderto determine the

solution's volume.

Procedure C - Density of Plastic by Displacement

1. Determine themass of the remainingBicround stic®pen barrel saved from Procedure B.

2. Record the volume of ethanol remaining in the buret.

3. Drop the barrel into the ethanol buret and record the new volume.

Calculations

1. Calculate the density of the two liquidsfromthe ProcedureA data.

/

573
2. Calculatethe mass of both liquids (M--dV)in the titrationusingthe densitiesobtainedin

Procedure A. Add the masses of water and ethanol to determine the solution's mass at

the end point.

3. Calculate the density of the plastic by using the solution's mass and volume. At the end

point, the solution's density is equivalent to that of the plastic.

4. Calculate the percentage of volume reductionof the titrated solution.

5. Calculate the plastic density again, this time using the barrel mass and volume displacement

of ethanol obtained in Procedure C.

6. Calculate percentage of errorfor the densitiesof water and ethanol. Calculate the

percentage of error for the densityof plastic determined by both titrationand ethanol

•displacement.

Notes to the Instructor:

1. No open flamesin the lab areashould be permitted. Wear protective eyewear and aprons.

2. This exercise has been useful in advanced high school and introductory college chemistry

classes. As a new twist to an old concept, it provides a vehicle for the early introduction of

volumetric methods. Students apply the density data for the two liquidsto determine the mass

of the titrated solution and become aware that the total volume of the titrated solutionis not the

sum of the volumes dispensed from the two burets. After calculating the approximate 4%

volume reduction, studentsshould attempt to explainwhy the solution's volume is lessthan the

sum of the volumes of the two liquids.

3. Percentage of error analysisis made on the densitiesof water, etlaanoland the plastic pen

barrel determined both by titrationand ethanol displacement. Percent errorfor the plastic

ranges from 0.00% to 6.0% by both methods, with ethanol displacement usually providing

betterresults. Students are encouraged to suggest weaknesses of both methodsthat might

account for errors.

4. The Bic round stic® pen was chosen because it isreadily available, fits in the 50 mL buret,

and is a common object in the lives of many students. Plastic containers imprintedwith

recycling code 4, low-density polyethylene (LDPE), and 5, polypropylene (PP), provide other

sources of plasticswhose density may be determined by titration using water and ethanol.

Additionalrelated studies can explore the separationand identificationof various plastics with

solvents of different densities as described by KolbS.

References:

1. Author to whom correspondence should be addressed.

2. Kolb, K.E.; Kolb, D.K.: "A Quick, Simple Demonstration to Distinguish between HD and

LD Polyethylene." J. Chem. Educ., Vol. 63, No. 5, May 1986, p. 417.

3. Craig, R.E.R.: "Determination of theDensity of Crystalline Solids in the Undergraduate

Laboratory." J. Chem Educ., Vol. 66, No. 7, July 1989, pp. 599-600.

574
4. Bic is a trademark of the Bic Corporation, Milford, CT 06460.

5. Kolb, K.E.; Kolb, D.K.: "Method for Separating or Identifying Plastics," J. Chem. Ed.,

Vol. 68, No. 4, April 1991, p. 348.

Source of Supplies:

Flinn Scientific Inc., P.O. Box 219, 131 Flinn Street, Batavia, IL 60510

575
Table: Sample of ExperimentalData andCalculatedResults

Procedure A Trial #1 Trial

#__g2

1. Volumeof ethanol 15.00 mL 15.00 rnL

2. Mass of ethanol 11.80 g 11.81 g

3. Calculateddensityof ethanol .7867 g/mL .7873

 rnL

[2+ 1]

4. Volume of water 15.00 mL 15.00 mL

5. Mass of water 14.93 g 14.88 g

6. Calculated density of water .9953 g/mL .9920

g/mL

[5+41

Procedure B

7. Volumeof water usedin titration 12.20 mL 12.50 mL

8. Volumeof solutionat endpoint 26.0 mL 26.0 mL

9. Calculatedmass of solution 23.94 g 24.21 g

[(7 x 6) + 2]

10. Calculated solution density and plastic density .921 g/mL .931

g/mL

[9+81

11. Calculated volume reduction 4.4% 5.5%

[(1 + 7) - 8] + [(1 + 7)] x 100

Procedure C

12. Massof pen barrel 1.77 g 1.82 g

13. Volumeof penbarrel 1.97mL 2.00 mL

14. Calculateddensityof barrelby displacement .898 g/mL .910

grnL

[12 + 131

15. Percenterrorby titration 1.99% 3.10%

16. Percenterrorbydisplacement .55% .78%

576
577

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1. AGENCY USE ONLY (Leaveblank) 2. REPORT DATE 3. REPORTTYPE AND DATESCOVERED

August 1995 Conference Publication

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

National Educators' Workshop:Update 94

Standard Experimentsin Engineering Materials Science and Technology 243-10-01-01

6. AUTHOR(S)

Compilers:JamesE.Gardner,NASALangleyResearchCenter,Hampton,VA,

JamesA.Jacobs,NorfolkStateUniversity,Norfolk,VA,

andAnna C. Fraker,NationalInstituteof StandardsandTechnolology,Gaithersburg,MD

7. PERFORMING ORGANIZATIONNAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION

REPORT NUMBER

NASA Langley Research Center

Hampton, VA23681-0001 L-17514

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

National Aeronautics and Space Administration,Washington,DC 20546-0001; NASA CP-3304 Norfolk State University,Norfolk, VA23504;

National Institute of Standards and Technology, Gaithersburg, MD 20899;

United States Department of Energy, OakRidge, TN 37831-6132

11. SUPPLEMENTARYNOTES

American Society for Engineering Education;ASM Foundation;Battelle, Pacific Northwest Laboratories;

Fernald Environmental Restoration ManagementCorp.; Martin Marietta Energy Systems, Inc.; Materials Education Council

12a. DISTRIBUTION/AVAILABIU'I'Y STATEMENT 12b. DISTRIBUTION CODE

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13. ABSTRACT (Maximum200 words)

This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop:

Update 94, held at the National Institute of Standards and Technology,Gaithersburg, Maryland, on November 7-9, 1994.

The experiments related to the nature and properties of engineering materials and provided information to assist in teaching

about materialsin the education community.

14. SUBJECT TERMS 15. NUMBER OF PAGES

Materials;Experiments;Education 618

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