QUARTERLY

Volume 6, Number 3

AMPTIAC is a DOD Information Analysis Center Administered by the Defense Information Systems Agency, Defense Technical Information Center and Operated by IIT Research Institute

Mobile Parts Hospital

Making Replacement Parts

in the Field

MaterialEASE: 

Tips and Pitfalls 

of Corrosion Testing
The AMPTIAC Quarterly is published by the Advanced Materials and Processes Technology Information

Analysis Center (AMPTIAC). AMPTIAC is a DOD sponsored Information Analysis Center, operated 

by IIT Research Institute and administratively managed by the Defense Information Systems Agency (DISA),

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than 25,000 materials professionals around the world.

Inquiries about AMPTIAC capabilities, products and services may be addressed to 

David H. Rose

Director, AMPTIAC

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Editor-in-Chief

Wade G. Babcock

Creative Director 

Cynthia Long

Information Processing

Judy E. Tallarino

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Training Coordinator

Christian E. Grethlein, P.E.

Every Defense researcher knows that our ultimate responsibility is to help our soldiers and sailors by providing them with

the best possible equipment and technology available. We take

this mission very seriously, and realize that our efforts will eventually save the lives of our countrymen by enabling them to do

their jobs better, from farther away, with more precision and

accuracy.

Our military is in the midst of a fundamental change in the

type of war it will wage in the future. We have spent the better

part of the past fifty years preparing to fight a well-organized

enemy, with massive war-making tools on the land and in the

sea and air. This enemy played by a similar rulebook to ours,

structured itself similarly, and basically had a fighting ability

and sense of morality not unlike our own. Our experiences

with enemies in Europe and Japan taught us much about how

to fight, but in the end we always knew who our enemies were,

and could invite them to a negotiating table to discuss peace.

In the 60s and 70s, we learned a valuable lesson: Much of the

technology we had developed proved less effective against a

loosely organized enemy with basic weapons and an intense

desire to defend their homeland. We learned to fight a guerrilla

war, in the jungles, ditches and swamps, with foot soldiers on

the ground the main asset to face the enemy. We learned a lesson we had initially taught the British almost two centuries

before: loosely organized militia with plenty of hiding places will

pose a difficult challenge to organized and structured troops

studying a well-defined rule book for how wars are supposed to

be fought. We also learned that intelligence gathering was going

to be a key ingredient of future combat. Our experiences in the

Far East thirty years ago again taught us much, but our primary

enemy was still the Soviet Union and Southeast Asia was only

one battle against Communism, not the entire war.

I am not a military historian, and these views are simply my

take on recent history that has led us to this point in time. Our

former enemies are now our allies, our new enemies are shrouded in mystery and our technology has many difficulties in

breaching their organizations. Our military faces far greater

challenges in today’s world: How do you fight an enemy that

we know so little about? How do you find out more? How do

you fight him in his own land, streets, and buildings? How do

you shift your war-making tools to policing tools after the battles are won? Indeed, how do you find someone who has practiced hiding to the point that it is an innate skill?

Our military is carrying out its new mission, but it is a mission that is still evolving. We are learning how to use the tools

we have in new ways, to accomplish new tasks that weren’t

envisioned just a few years ago. We are learning to focus more

on information in the battlespace, such that resources are used

in the most effective manner possible. Constant vigilance is our

only ally, because our new enemy is very creative, devious and,

above all, patient

But back to us, the Defense materials and processes community. Our mission of supporting our military is a challenging

one. We are often so far from the "point of the spear" that we

risk loosing sight of our mission, and sometimes we even struggle with our own political opinions. Simply put, our job is to

create the new materials and technologies needed for remote

sensing, force protection, intelligence gathering, guidance, control, and weapons systems. Existing tools will be modified and

new ones designed to fit the needs of a new and very different

kind of war. Advanced materials are just as important in

enabling today’s new systems and capabilities as they were in

the past. We must also realize that our focus may have to evolve

to recognize new opportunities. But when all is said and done,

our mission is simply to provide our warfighters with the

equipment they need to do the job, and in that, we will not fail.

Wade G. Babcock

Editor-in-Chief

Editorial: Survival of the Fittest

CORRECTION: On page 7 of the last issue of AMPTIAC Quarterly, in Figures 3 and 4 of the article

“Lowering the Cost of Titanium,” the Internet address for AeroMet Corporation was incorrectly identified.

The correct Web address is www.aerometcorp.com. We apologize for any inconvenience this may have caused. 
The AMPTIAC Quarterly, Volume 6, Number 3 3

Stan Kolisch

IIT Research Institute

Introduction

The U.S. Army, through its Tank-automotive and Armaments

Command (TACOM), is engaged in an R&D program to

develop a capability to produce replacement parts for equipment in the field at or near the point-of-need. This capability

will enable the rapid repair and return to service of disabled

equipment and address the military priority of weapon system

readiness.

The program, titled the Mobile Parts Hospital (MPH)*, is

analogous to the Mobile Army Surgical Hospitals (M.A.S.H.).

Since their inception, M.A.S.H. units have been effective at

returning soldiers to health in the field. The MPH units are

designed to do the same for Army equipment. The overall

approach is to develop a mini-factory that can be deployed in

the field to manufacture replacement parts in order to return

disabled military equipment quickly to operational and combat-ready status.

The Army faces a major challenge in equipment maintenance and combat readiness in today’s environment. It must

continue to meet readiness standards while maintaining a large

aging inventory of weapon systems. Increasing the effective

service life of these legacy systems has led to an increased

demand for spare parts, many of which are from product lines

or manufacturers that no longer exist. Because the Army is purchasing fewer systems (and in significantly reduced volumes),

suppliers assign lower priority to the Army’s production and

schedule requirements, thereby increasing product lead times,

particularly for forged and cast items. Additionally, the Army is

poised to introduce several new systems into the inventory,

many of which will pose logistical challenges when fielded.

MPH is meant to address this challenge by significantly reducing the lead-time needed for replacement parts. The Army is

actively developing advanced logistical systems to address these

challenges. The MPH will play an integral role in supporting

these new systems, and will continue to support current supply

systems.

As the MPH program has progressed, three major developments have evolved 1) the mobile modules referred to as the

rapid manufacturing system (RMS), 2) an agile manufacturing

cell linked to the RMS via 3) the control and communications

center.

Technical Challenges

The MPH manufacturing capability must meet the following

requirements to be effective: be readily transportable, have a

small logistics footprint, and be able to fabricate parts for which

there is a critical need. These requirements translate into some

important technical challenges.

Transportable: The RMS is limited in size and weight and

must be configured so that it is transportable by C-130 aircraft

and/or the Army’s Palletized Load System. The number of

pieces of equipment is limited by this volume requirement, but

the system must maintain the capability to make a wide range

of necessary parts. Consequently, the production equipment

selected must be compact and sufficiently flexible to make a

variety of parts. Moreover, ancillary operations such as heat

treatment or plating need be kept to a minimum.

Logistics Footprint:To maintain a small logistics footprint on

the battlefield, the RMS must be self-sustaining in terms of

power, environmental, communications and inventory needs.

The current RMS prototype designs address these factors. Of

particular significance is the need to minimize the amount and

variety of material stock required to make the desired parts. This

translates into the need for flexible fabrication processes to enable

the production of a variety of parts from limited material stock

that meet the functional engineering requirements of the part.

* www.mobilepartshospital.com

Materials are enablers of technology – this is an axiom that most materials specialists know and embrace. Typically, we tend to think of

such materials in terms of fielded hardware and the added performance they provide. What is not always considered yet equally true, is

that materials enable new and improved manufacturing processes and technologies as well. Thus, new materials not only afford us with

systems that perform better, but they also allow us to produce such systems at higher rates, lower costs, and with higher degrees of quality

and reliability. The advances in powder metallurgy over the past two decades have facilitated a series of rapid prototyping and

manufacturing technologies, which are allowing us to redefine the conventions of manufacturing and production. The Army’s Mobile 

Parts Hospital is an excellent example of harnessing the potential of such emerging technologies. - Editor
Critical Parts: Above all, a flexible fabrication capability is

necessary to produce the range of critical parts required.

During the development of the MPH, a parts selection process

has been employed to identify select parts that: impact on systems readiness due to high cost, are not readily available

(because of lack of suppliers), require a long lead time, and

directly impact mission success. To provide MPH with the

capability to make all these parts, a database is being built that

houses the engineering and manufacturing data required to

produce them. In addition, MPH integrates a satellite communication capability to transfer data from remote sites and

includes a capability for reverse engineering when no data are

available. The need for flexible manufacturing processes permeates the overall requirements for the MPH program. This

flexibility has been facilitated by the adoption of advanced

metal-cutting technology, as well as by the conversion of rapid

prototyping technology into rapid manufacturing systems.

Rapid Manufacturing System

MPH mobile modules are designated as Rapid Manufacturing

Systems (RMS). The RMS is a mobile manufacturing system

that can produce parts rapidly near the point of need. The initial MPH utilized a 53-foot enclosed trailer, similar to a standard road-going tractor-trailer arrangement. Transportation

requirements however, dictated a smaller footprint. The current

RMS prototype consists of two twenty-foot expandable 

ISO-standard (International Standards Organization) freight

containers, each housing one primary piece of fabricating

equipment. Each of these modules meets the size and weight

requirements for a C-130 transport plane and can be moved

overland on Army trucks. The first module contains a Directed

Material Deposition (DMDTM) machine that utilizes a patented process called Laser Engineered Net Shaping(TM) (LENS®).

LENS® can create a fully dense metal part from a computer

aided design (CAD) model, which is converted to a standard

triangulation language (STL) file. This module has a 20' by 8'

footprint when stowed, but is designed to expand to 20' by 24'

when deployed. (See Figure 1)

After a part is built “near net shape” with this process, it is

directed to the other machine – a 5-axis multi-task machining

center for final finishing and dimensioning. This machine is

housed in a 20' by 8' container that expands to 20' by 12' when

deployed (See Figure 2). In addition to the major machines

inside each module, there is also an engineering workstation

with both engineering and manufacturing software, a satellite

communications system, and a reverse engineering capability

4 The AMPTIAC Quarterly, Volume 6, Number 3

LENS®

Laser

Chiller

LENS®

Laser

Chiller

LENS®

Machine

LENS®

Machine

LENS®

Control

Fold Down

Work Table

Fold Down

Work Table

Scanner

Scanner w/Engineering

Workstation

LENS®

Control

HVAC

Unit

HVAC

Unit

Laser

Laser

Argon

Container

Argon

Container

HVAC

Unit

Tool

Cabinet

Tool

Cabinet

HVAC

Unit

Air

Compressor

Tool

Cabinet

Multitask

Machining Unit

(MAZAK®)

Multitask

Machining Unit

(MAZAK®)

HVAC

Unit

HVAC

Unit

Tool

Cabinet

Figure 2. Multitask Machining Center Module

Air

Compressor

Figure 1. Directed Material Deposition Module

Entrance Entrance

Entrance

Entrance

8’ Stowed 

Configuration

12’ Operational 

Configuration

20’

8’ Stowed 24’ Operational Configuration Configuration

20’

LENS® is the registered trademark and service mark of Sandia National Laboratories and Sandia Corporation

Laser Engineered Net Shaping(TM) is a trademark of Sandia National Laboratories and Sandia Corporation
The AMPTIAC Quarterly, Volume 6, Number 3 5

including laser-scanning equipment to capture part geometry

from old parts in need of replacement.

When a request for a part comes to the RMS, its on-board

databases are searched to determine if that specific part (or one

similar to it) has been built before, and if the manufacturing

data are available. To manufacture an article, the RMS must

have a complete 3-Dimensional model of the requested part. If

the required data were not available in the databases, on-board

equipment could be used to create it – using the CAD/CAM

software in combination with the non-contact laser scanner.

Once a 3-D model is obtained, the file is converted to a format

used by the LENS® manufacturing process.

Laser Engineered Net Shape Process

The LENS® process is considered a DMD process because 

powdered metal is directed into the path of a laser beam, where

it is melted and then solidified on the workpiece, creating a

component, particle-by-particle and layer-by-layer. The properties of metal parts created using this process can be made 

equivalent to and potentially better than those of wrought

material of the same composition. In addition, the time to 

create a part using this process, compared to casting or forging,

is greatly reduced (See Figures 3 & 4). 

The LENS® process is an emerging technology which is still

maturing, thus both development and testing of LENS® continue in the MPH program. Controlled process optimization

studies, employing design of experiments (DOE) methodology,

are underway to relate process variables to resulting material

microstructures and mechanical properties. In addition to 

relating the process variables to material properties, the experiments are designed to identify methodologies for increasing

processing speed, improving surface finish, and maximizing the

configurational capabilities of the process. Key process variables

include laser power, powder feed rate, weld pool size, and beam

path control strategy.

A major asset of the LENS® process is the ability to make free

form (without molds or dies) metal parts of high-density and

near-net-shape, enabling the MPH system to make a variety 

of parts. Inclusion of this process enhances MPH’s mobile 

processing capability. Because the process is based on powder

technology, the material inventory can be dramatically reduced,

as there is no need to store varieties of solid stock, in turn

reducing the footprint of the facility. In addition, the ability of

the process to consolidate a number of high performance alloy

powders (e.g. high alloy steel, titanium) permits MPH to 

operate with a reduced material compositional inventory by

building parts to better than original part properties. In this

strategy, a single high performance alloy can be employed for a

whole family of parts, yielding mechanical properties equal to or

better than those in the original parts. Consequently, the compositional varieties of powder stock can be kept to a minimum

in the materials inventory. Finally, the near-net-shape capability

minimizes scrap, which consequently reduces the required total

of the powder stock inventory. The ideal goal of the MPH program would be to carry a single powdered metal to the battle

space that would meet all part property requirements. 

The Multitask Machining Center

Post-processing of parts made by the LENS® process requires

the use of a second piece of manufacturing equipment, the 5-

axis multitask milling machine to meet surface finish and tolerance specifications. The second ISO module of the RMS contains this 5-axis multi-task-machining center. This machine is a

multi-axis mill that is set up primarily as a lathe. Work pieces

such as gears and camshafts that normally would require 

separate turning centers, and both vertical and horizontal

machining centers, can now be completely machined with efficiency and accuracy in the multi-task machining center. All

axes are direct motor driven with no belts, pulleys, or gears, and

tool exchange speed is nearly instantaneous (See Figure 5).

The milling machine incorporates an integrated 64-bit 

computer numerical controller (CNC), color graphics display,

and a simple programming language. In addition to having the

capability of directly inputting machine code, the programmer

Figure 3. Directed Material

Deposition Machine (Exterior View)

Figure 4. Directed Material Deposition

Machine (Interior View)
can also simply input the dimensions in a logical machining

sequence (guided by the machine). The video display unit

shows a shaded model of the work-piece for each stage, including a model of the cutting tools in action. This can be seen

dynamically for an entire program prior to cutting material and

while the actual machining is in progress. During programming, the controller immediately flags any x-y-z interference 

or an unfeasible operation as an error, and the corresponding

program line is highlighted for correction.

The 64-bit controller is capable of making tool path adjustments on the fly (OTF) to compensate for tool wear. Any 

manual adjustments (tweaking) done by the operator while the

program is running can be recorded by the controller and

immediately incorporated into the master program file, if

desired. Another capability of this machine is the ability to

record cutting path data in the event of tool breakage. These

data (up to 5 motions) are recorded as the operator manually

guides the tool away from the work-piece for changing. At the

restart command, the stored cutting path data guides the tooling back to the interrupted stage position, and the original program continues. There is no need to return to the program

beginning, saving significant time over conventional methods. 

Agile Manufacturing Cell

Although the mobile RMS can successfully manufacture a variety of parts, it has repair part size and weight restrictions based

on mobile process limitations. Several critical parts are either

too large or have manufacturing requirements that are simply

impractical for a mobile manufacturing environment. A prototype agile manufacturing cell (AMC) has been designed to 

support the mobile RMS. This flexible manufacturing would

be located in the U.S. but would serve as a support system

capable of handling these larger repair parts and processes not

available in a mobile unit. The AMC will also be able to produce larger quantities of parts (50-100 each) in contrast to the

RMS that is designed for low volumes on an as-needed basis.

Control and Communications Center (C2)

The C2 is the link for direct communication between the

mobile systems and the U.S. based agile manufacturing cells.

An essential function is the management and transmission of

the engineering and manufacturing data required to produce

replacement parts.

The program’s engineering and manufacturing database

serves as the manufacturing foundation for the MPH program.

The part database is managed by product data management

software (WindChillTM) that is incorporated into the communications center. This software is designed to operate in a distributed engineering environment and consequently facilitates

the control and transfer of information between multiple units.

Producing parts on demand with a CAD/CAM data library

provides a distinct advantage in timeliness. When the data are

not available in the database, outside sources must be queried

or reverse engineering is required. The MPH program continually identifies and adds parts to this database by gathering or

creating manufacturing data. The ISO Standard for Exchange

of Product (STEP) data format is the current, universally

adaptable CAD language and manufacturing data format of

choice, and is being utilized by the MPH program.

The C2 utilizes a two-way satellite system to provide the

communications link between the AMC, the RMS, and the

Army’s established logistics systems. The system provides audio,

video, and data exchange capabilities. The C2 satellite data

transfer system can receive/send both CAD and/or CAM data

from the RMS located anywhere in the world. The transferred

data can be directly fed into either of the manufacturing

machines or into the CAD/CAM workstation for further

model definition and storage.

The CAD/CAM database of parts and raw material procurement would logically be handled in a central location.

TACOM-TARDEC (Warren, Michigan) is a likely location for

the communications and control center, which will network

the RMS fleet and agile manufacturing cells. Tentative plans are

to merge the MPH C2 activities with those of the Emergency

Operations Center already located at TACOM.

Summary

The development of a mobile manufacturing capability to 

produce replacement parts in the field will provide the Army

with the ability to reduce spare parts inventory, reduce the cost

and size of logistics operations, and provide for increased operational readiness. It is designed to complement existing supply

systems and to integrate with the advanced logistic systems

being developed for the Army of the future. Ultimately, the

goal of MPH is to increase and enhance the effectiveness of our

combat commanders.

The MPH program is working with emerging technologies

to achieve the manufacturing capabilities needed for the mobile

environment. The most advanced rapid prototyping and manufacturing processes available today are not yet adequate to fulfill all the requirements of the MPH program, but great strides

have been made in recent years. In the future, the MPH program can look forward to increased and broadened capabilities,

producing better parts from a wider range of materials at faster

build rates, with greater configurational range and accuracy.

For more information on the MPH, visit www.mobileparts

hospital.com.

6 The AMPTIAC Quarterly, Volume 6, Number 3

Figure 5. Multitask Machining

Center
MatML is an extensible markup language for the automated

exchange of materials property data. In development since

October 1999, MatML presently exists as a working draft, and

is being revised in anticipation of its public release as a proposed

recommendation. This article provides a brief description of

MatML, including its history and sample markup. The vision of

a future materials data exchange environment in which MatML

will serve all parties with an interest in the promulgation of

materials property data is also discussed.

Introduction

The World Wide Web is clearly one of the most remarkable

developments of 20th century computing. From extremely

modest beginnings in 1990 at CERN, the European

Organization for Nuclear Research, the Web has grown exponentially to the point where today it is by far the largest source

of information ever assembled.

Like any information technology resource, the Web is supported by an extensive hardware and software infrastructure.

One of the major components of the software infrastructure is

hypertext markup language, or HTML, which is used to format

nearly all of the content presently available on the Web.

In recent years, the World Wide Web consortium (W3C –

http://www.w3.org), the organization responsible for the various standards underlying the Web, including HTML, has

found HTML to be insufficient for the processing and

exchange of structured data via the Web. Responding to this

insufficiency, the W3C in February 1998 released the

Extensible Markup Language (XML), which is actually a

meta-language for defining markup languages used to

describe domain-specific information. Various communities

of specialists interested in exchanging data specific to their

field have since come forward and developed markup languages based on XML. This article describes the efforts and

results of the materials community in developing MatML, a

markup language for describing and exchanging materials

property data.

What is MatML?

In May 1999, a workshop entitled “Materials Data in the

Internet Era” was held at the National Institute of Standards and

Technology (NIST). The attendees recognized the tremendous

potential of XML, which had been released the year before and

was already beginning to spawn markup languages in various

scientific and technical domains. In the fall of 1999, E.F. Begley

of NIST assembled an international working group of about 40

materials data experts to determine the scope of MatML, a new

language for materials property data, and formulate its vocabulary and syntax.

Perhaps the best way to describe MatML is by example and in

contrast to HTML. Table 1 contains an excerpt of data drawn

from the NIST High-Temperature Superconducting Materials

Database (WebHTS) as it would appear when rendered by a

web browser.

The AMPTIAC Quarterly, Volume 6, Number 3 7

Dr. Charles Sturrock, Dr. Edward Begley

National Institute of Standards and Technology

Those of us who have dealt with the utilization, storage, or transfer of materials property data are well aware of the difficulties (and pitfalls)

of handling such design-critical information. Whether in printed form (such as the MIL-Handbooks), or in electronic form (such as 

material property databases or material information systems), assimilating and displaying such data has proven to be a daunting task, and

in some cases, an insurmountable one. The advent of the World Wide Web significantly advanced the state-of-the-art in information

exchange. More than a decade since the initial revolution, a second generation of exchange languages has emerged, with greater flexibility

and adaptability to the parochial terminologies of a disparate number of professions; such as chemistry, medicine, law, and even finance. 

For those of you who have wrestled with the challenges of material data standardization, data quality, or the handling of mass quantities of

materials property information, the virtues and benefits of a materials-specific exchange language will be immediately obvious. For those not

familiar with the topic, enjoy this first glimpse into the future! - Editor
8 The AMPTIAC Quarterly, Volume 6, Number 3

The HTML markup for this table is as follows, with the tags

shown in italics and the data shown in normal text:

<table>

<tr>

<td align=“center”><b>Magnetic Field (Tesla)</b></td>

<td align=“center”><b>Temperature (K)</b></td>

<td align=“center”><b>Critical Current Density 

(kA/cm<sup>2</sup>)</b></td>

</tr>

<tr>

<td align=“center”>0</td>

<td align=“center”>3</td>

<td align=“center”>3040</td>

</tr>

</table>

Note that the tags in HTML specify only how the data are to

be presented, and convey no descriptive content whatsoever.

Here is the same excerpt in MatML markup:

<Properties>

<PropertyDetails>

<Name>Critical Current Density</Name>

<Units>kA/cm<sup>2</sup></Units>

<DataSource>Journal</DataSource>

<DataType>Evaluated</DataType>

</PropertyDetails>

<Value>3040</Value>

<Parameters>

<Name>Magnetic Field</Name>

<Value type=“integer”>0</Value>

<Units>Tesla</Units>

<Name>Temperature</Name>

<Value type=“integer”>3</Value>

<Units>K</Units>

</Parameters>

</Properties>

The descriptive nature of the MatML tags, such as

<Properties>, <Name>, and <Units> is plainly evident. Note also

that the MatML version includes other information about the

pedigree of the data, as conveyed by <DataSource> and

<DataType>. MatML, like all extensible markup languages,

provides for any number of user-defined tags such as these. The

descriptive nature and extensibility of the language renders it

far more intelligible and malleable than non-descriptive fixed

tagsets such as HTML.

MatML presently exists as a working draft in XML

Document Type Definition (DTD) format. Table 2 contains

the complete tagset for the language. An annotated version of

the entire DTD, along with many other MatML-related

resources, can be found at the MatML website:

http://matml.nist.gov/.

June 2001 MatML Workshop

Last summer, members of the materials data community convened at NIST at a workshop devoted to the technical and

strategic future of MatML. The proceedings of this workshop

can be found at the MatML website. In brief, the main findings

of the workshop were as follows:

• The development of MatML has been met with great

interest, with frequent visits to the MatML website, downloads of the DTD, and inquiries to NIST and other parties that have contributed to the development of the language;

• The extensibility of MatML makes it possible to address

the full range of materials information needed by materials researchers, specialists, designers, and quality control

analysts, as well as the full range of materials-related applications used by these professionals;

• MatML markup is relatively easy for materials scientists and

engineers to understand, as the code consists largely of

materials and engineering terminology (see previous example), which has the key advantage of enabling materials specialists to review the markup in detail to ensure that all of

the required parameters involving test methods, quality, reliability, and applicability of the data have been addressed;

• A good set of illustrations demonstrating the power and

flexibility of MatML should be established in order to

advance the widespread adoption of MatML;

• MatML must be tested thoroughly, involving individuals

at various stages in the material development/application

cycle ranging from materials specialists who select materials to designers responsible for addressing load-carrying

capacity and failure limits. In addition, the needs of materials scientists exploring the fundamental structure and

properties of materials, and of journal publishers disseminating materials information, must also be addressed;

• At the appropriate time, MatML should be recognized

officially and formally via registry with XML repositories

such as xml.org and/or by standards organizations such as

the Object Management Group, the American Society for

Testing and Materials (ASTM), or the American National

Standards Institute (ANSI);

Table 2. MatML DTD Version 2.0 Complete Tagset

Associate Elements Processing

Associations Form Properties

Bulk Details Formula Property Details

Characterization Geometry Qualifier

Chemical Composition Graphs Relationship

Class Material Result

Component Details MatML–Doc Shape

Compound Measurement Technique Source

Concentration Name Specification

DataSource Notes Subclass

Data Type Orientation Terms

Dimension Details Parameters Units

Dimensions Phase Composition Value

Table 1. Tabular Display of Data Excerpt from WebHTS

Magnetic Field (Tesla) Temperature (K) Critical Current Density (kA/cm2)

0 3 3040
The AMPTIAC Quarterly, Volume 6, Number 3 9

• The overall effort should be linked with key industries,

that might, via some of their applications, be in position to

provide good tests for MatML and, assuming success,

encourage or perhaps even require users of their information systems to use MatML as the data exchange medium.

MatML - Present and Future

MatML is presently being revised to be reissued in XML

Schema representation. XML Schema provides robust data 

typing, including user-defined datatypes, and is much more

suitable for application development than XML DTD representation. The next phase of MatML’s development will involve

acceptance testing, and migrating to MatML Schema will 

provide sound support for such testing.

With respect to acceptance testing, there are two principal

kinds of XML applications: document publishing and document processing. Document publishing, which is the manipulation of information for human consumption, by necessity,

comes first and will exhibit the strengths and weaknesses of

MatML. In a sense, acceptance testing is already underway with

the development of a compendium of markup examples, but

wider participation is needed in order to assess MatML’s application to a broader and deeper range of materials. Future NIST

testing might include markup of NIST WebSCD, NIST

WebHTS, and NIST WebPDS, which are online compilations

of structural ceramic, high temperature superconductor and

property data summaries, respectively.[1]

Document processing, which is the manipulation of information intended for software consumption, represents the second phase of MatML’s acceptance testing. While no specific

plans have yet been identified, several projects are already

exploring the use of MatML, including:

• Green’s Function Research and Education Enhancement

Network (Kent State University, Massachusetts Institute

of Technology, NIST, (Web address:

http://shreve.mcls.kent.

edu/NSDLGreen/GREENProject.htm));

• femML – the finite element modeling markup language

(J. Michopoulos, U.S. Naval Research Laboratory, (private communication)).

Another important issue is education. It is not sufficient to

publish MatML simply as a language specification. It is necessary to provide additional resources to promote understanding

and adoption of the new language. This philosophy was behind

the publication of MatML in an annotated format on the

MatML website, where, in addition to the syntactic and semantic formalism of the language, English language explanations

are provided as well as sample markup. Examples of other 

supporting resources for MatML found on the MatML website

include links to sources of information about XML, and 

related expositions such as “XML, Element Types, DTDs and

All That.” Finally, the compendium of markup examples will

be extremely valuable for assisting users with learning how to

apply MatML to their own data.

Presently the three main strategic issues for MatML are: promotion and outreach, MatML registration, and long-term

stewardship. Direct communications, journal publications, the

MatML website, conference presentations, and the MatML

workshop proceedings can be used to reach data providers and

consumers such as journal editors, handbook and database

publishers, materials suppliers (data sheets), instrument manufacturers, and researchers. Registering MatML with the

www.xml.org registry as well as the NIST registry/repository

for XML may also provide broader exposure and access to

MatML.[2]

The MatML Steering Committee has been established to

oversee and promote continued development and adoption of

MatML, to coordinate acceptance testing activities, and to

explore opportunities for MatML’s long-term stewardship. Its

members include:

J.G. Kaufman, Chairman, the Aluminum Assoc. (ret.)

E.F. Begley, Lead Technical Expert, NIST

F. Cverna, ASM International

C. Grethlein, AMPTIAC

S. McCormick, ESM Software

D. Mies, MSC Software

C. Nunez, CenTOR Software Corporation

C. Sturrock, NIST

M. Sullentrup, Boeing Company

The MatML Steering Committee represents the interests of

a much larger community of materials and computing professionals interested in MatML and its objective of automating the

exchange of materials property data over the Web. This larger

community is in turn kept abreast of developments via the

MatML website and dedicated mailing list (for information

contact begley@nist.gov).

At present, the materials data “marketplace” can be very

chaotic and difficult for both providers and consumers. Until

the arrival of MatML, there was no common exchange format,

but instead hundreds of proprietary formats that resulted in

wasteful duplication of effort and poor scale-up. Also plaguing

the materials data community was (is) the absence of software

interoperability, whereby one computer program, such as a

finite element code, can automatically input material properties

from another computer program or database without the necessity of human intervention. The present situation overall yields

very inefficient data processing.

MatML will serve the materials data marketplace as a 

common, public-domain materials data exchange format - a

non-proprietary “Esperanto” for materials property data. With

considerable flexibility and extensibility built-in as attributes of

the language, MatML will provide for direct program-toprogram interoperability, efficient data processing, and rapid,

reliable, and useful response to searches for materials data over

the Web. Its widespread adoption will provide for powerful and

malleable connection of the various materials data sources

found on the Web today, as well as those to be added to the

Web tomorrow.

References

[1] For more information, see the Ceramics WebBook at

http://www.ceramics.nist.gov/webbook/webbook.htm

[2] For more information, see the MatML website at

http://matml.nist.gov
10 The AMPTIAC Quarterly, Volume 6, Number 3

As the contents of the AMPTIAC Quarterly might suggest, we

are in the business of promoting materials technology and technology transfer within the materials and defense communities.

What you may not know is that AMPTIAC also offers a variety

of products, printed and electronic, to promote technical awareness and serve as an educational resource for the community.

Our complete and interactive product catalog, along with

descriptions of our other technical services, are available for

viewing at the AMPTIAC website, http://amptiac.iitri.org/

ProductsAndServices. If you have any questions about any of our

products, or if you would like to order one or more of them,

please contact our Product Sales Manager, Gina Nash at (315)

339-7047 or e-mail at gnash@iitri.org. 

This past year has been an exceptional one for AMPTIAC,

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Regardless of your specific discipline, there is an AMPTIAC

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AMPTIAC surveyed DOD, government, and academic efforts

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and from this research compiled this report. It provides and indepth examination of CMS and describes many of the programs,

techniques, and methodologies being used and developed. The

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Special attention was paid to novel combinations of materials

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sponsored by Dr. Lewis Sloter, Staff Specialist, Materials and

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New AMPTIAC Products Available Now
“Corrosion is Corrosion” – we have heard that all too often at the 

AMPTIAC inquiry desk. In our experience, corrosion is one of the most misunderstood and mischaracterized forms of material degradation.

Consequently, corrosion analysis and mitigation methods tend to be some of

the most misapplied. This MaterialEASE is the third and final installment

excerpting a new AMPTIAC State-of-the-Art Review entitled “Accelerated

Testing: A Methodology for Determining Life and Degradation of Materials”.

It will be published in the near future. This article examines the fundamentals

of accelerated corrosion testing, the associated pitfalls therein, and what

tools today’s materials engineer will have to battle corrosion.

The Problem:

As recently as 1995, a major study concluded that the cost impact of corrosion to the U.S. economy totaled nearly $300 billion annually.[1] This represents nearly 4% of the Gross Domestic Product, and is a conservative estimate at best – indirect costs, which are substantial and mostly unreported,

would greatly inflate the total estimated cost. Estimates suggest that about

two-thirds of present corrosion-related costs are unavoidable. In addition, corrosion affects our Nation’s force effectiveness and readiness levels through

the diminished safety and reliability of structures, mechanisms and electronics.

In many cases, corrosion is the life-limiting factor of a component.

Corrosive failures can occur unexpectedly at the worst possible moment.

Corrosion testing can consume enormous blocks of time; particularly in the

case of outdoor atmospheric tests. Unfortunately, the timescales involved in

such tests preclude the opportunity for proper materials selection. In typical

circumstances, new systems may be halfway through their lifecycle before

real data on the fielded system would indicate any corrosion problems.

Under the right conditions, accelerated testing may yield data beneficial in

selecting the most corrosion resistant materials for an application.

Accelerated testing isn’t limited to the design stage of a system’s lifecycle, but

can be used to provide in-field support, as the emergence of sudden corrosion problems on fielded systems requires quick answers.

Managing corrosion in structural components and critical systems, to

extend service life and ensure reliability, is paramount. Effective corrosion control requires meaningful test data in a reasonable time frame such that it may

be employed to influence materials selection and protection efforts. There are

presently hundreds of existing accelerated corrosion test methods and no

doubt there will be many more in the future.

Background

The most accepted definition for corrosion is the destruction of material due

to a chemical reaction of the material with its environment. Generally, this

destruction takes place on its surface in the form of material dissolution or redeposition in some other form. Metallic systems are the predominant materials of construction, and as a class, are generally susceptible to corrosion.

Consequently, the bulk of corrosion science focuses upon metals and alloys.

Corrosion does occur in polymers and ceramics but the mechanisms are

quite different from those of metals. As such, this article limits itself to a discussion of metallic corrosion.

The Electrochemical Process

Corrosion consists of an oxidation reaction and a reduction reaction at the

surface of the corroding material. The oxidation reaction generates metal

ions and electrons; the electrons are then consumed in the reduction reaction.

For environments with water present including moisture in the air, the electrons

are consumed by converting oxygen and water to hydroxide ions. In iron and

many iron alloys, these hydroxide ions in-turn combine with iron ions to form

a hydrated oxide (Fe(OH)2). Subsequent reactions form a mix of magnetite

(Fe3O4) and hematite (Fe2O3). This red-brown mixture of iron oxides is rust.

The figure below illustrates the basic oxidation/reduction reaction behind

corrosion.

The higher the ionic conductivity, the quicker this reaction takes place.

This is why water containing electrolytes, such as salt, is far more damaging.

Another key point to note is that reducing the amount of dissolved oxygen in

solution directly can inhibit corrosion. However, many other reduction reactions can consume the electrons.

AMPTIAC Material 15

EASE

ACCELERATED CORROSION TESTING

Jeffrey Guthrie, Brigitte Battat and Chris Grethlein

AMPTIAC, Rome, NY

19 AMPTIAC

The AMPTIAC Quarterly, Volume 6, Number 3 11

OH OH OH OH

Iron

e e e e

Fe+2 Fe H2O +2 H2O O2

Figure 1. Electrochemical Process
Material EASE

12 The AMPTIAC Quarterly, Volume 6, Number 3

Table 1. Traditional Corrosion Classifications[3].

Uniform (General).. Occurs evenly over the entire surface. The rate of corrosion is often presented as a weight loss. Uniform corrosion is very 

predictable, and is the basis of most corrosion prediction equations.

Galvanic .................. Corrosion caused by an electrochemical reaction between two dissimilar metals when placed in contact or electrically connected with each other in an electrolyte.

Crevice .................... A localized form of corrosion which occurs within the stagnant zones created by the interfaces between two surfaces. Crevice

corrosion can occur under washers, gaskets, debonded coatings, surface deposits, sealing rings, rivets, sleeves, surface scale,

switch contacts, clamps, etc. The diverse environmental factors causing crevice corrosion make it almost impossible to simulate

field conditions in the laboratory. Predicted life from accelerated tests is also unlikely.

Pitting ...................... Pitting corrosion is a localized form of corrosion that proceeds with minimal overall metal loss, making it difficult to detect.

Consequently, it is difficult to predict, and its rate of attack is hard to quantify, as its reaction rate is not quantifiable.

Intergranular .......... This phenomenon occurs preferentially at grain boundaries, usually with slight or negligible attack on the adjacent grains.

Selective Leaching .. One element is preferentially removed from an alloy, leaving a residue (often porous) of the elements that are more resistant to 

the particular environment. It is also called de-alloying or parting. Common forms of selective leaching are decarburization,

decobaltification, denickelification, dezincification, and graphitic corrosion. 

Erosion .................... An action involving both corrosion and erosion in the presence of a moving corrosive fluid, leading to the accelerated loss of 

material.

Stress ...................... Induced by the joint influence of mechanical stress and corrosion processes. Static-tensile stress causes stress corrosion cracking (SCC). The stresses initiating SCC damage are in the form of applied mechanical stress or residual stress. Manufacturing

processes such as welding, bending, cold deformation (cold working), or electroplating of metallic components can bring

about residual stresses. Differences in the coefficients of thermal expansion (CTE) of the materials in contact increase the risk of

SCC. Corrosion fatigue is often considered to be a form of SCC. Cyclic loading brings about corrosion fatigue.

General Corrosion:

Corrosive attack 

dominated by 

uniform thinning

• Atmospheric Corrosion

• Galvanic Corrosion

• Stray-Current Corrosion

• General Biological

Corrosion

• Molten Salt Corrosion

• Corrosion in Liquid 

Metals

• High-Temperature 

Corrosion

Localized Corrosion: 

High rates of metal 

penetration at 

specific sites

• Crevice Corrosion

• Filiform Corrosion

• Pitting Corrosion

• Localized Biological

Corrosion

Metallurgically

Influenced Corrosion:

Affected by alloy 

chemistry & heat 

treatment

• Intergranular Corrosion

• Dealloying Corrosion

Mechanically Assisted

Degradation:

Corrosion with a 

mechanical component 

• Erosion Corrosion

• Fretting Corrosion

• Cavitation and Water

Drop Impingement

• Corrosion Fatigue

Environmentally

Induced Cracking:

Cracking produced 

by corrosion, in the 

presence of stress.

• Stress-Corrosion 

Cracking (SCC)

• Hydrogen Damage

• Liquid Metal 

Embrittlement

• Solid Metal Induced

Embrittlement

Table 2. Forms of Corrosion – ASM Classifications[4].
AMPTIAC A DVANCED M ATERIALS AND P ROCESSES T ECHNOLOGY

The AMPTIAC Quarterly, Volume 6, Number 3 13

The corrosion of iron illustrates that many reactions can occur. Similar to

iron, aluminum forms an oxide scale; however, the oxide scale formed (alumina) is cohesive, adherent and inhibits further corrosion. The oxide film formed

ennobles the metal and reduces electrical current density by as much as six

orders of magnitude. Materials like aluminum exhibit three corrosion regions:

a. Active Region -Increases in the oxidation potential lead to increasing corrosion rates. This region corresponds to the beginning of corrosion. 

b. Passive Region - Increasing the oxidation potential past the active region

reduces the corrosion rate.

c. Transpassive Region - Increasing the oxidation potential past the passive

region, increases corrosion rate.

If the oxidizing potential is raised to high enough levels the oxide film

breaks down and the material begins to actively corrode again. Given the

many reactions that can occur and the corrosion regions possible, accelerating the corrosion process is difficult without altering the corrosion mechanism. 

Categorizing corrosion forms into specific groups is not straightforward,

because such groups have overlapping characteristics, which influence the initiation and propagation of corrosion. However, corrosion is often categorized

by how it manifests itself, as described in Table 1, Traditional Corrosion

Classifications. 

Classes of Corrosion

ASM offers a complementary classification of corrosion that can be useful for

designers. This classification, shown in Table 2, categorizes various corrosion

processes by mechanism of attack. Inspection of this table indicates that some

forms of corrosion affect (relatively) large areas as indicated in the section

addressing “General Corrosion” while other mechanisms are very local in

nature. Other corrosion mechanisms are facilitated by metallurgical factors

while still others rely upon the movement of two structures relative to each other

or a structure or component subjected to moving fluids or slurries. The final category identifies corrosion mechanisms that result from the inspection of a

“stressed” material in the presence of a corrosive agent. Some of these mechanisms can be easily dealt with or mitigated through proper design and materials selection decisions. Accelerated testing can be a useful tool in this process

as long as the investigator realizes the intent of the test. Accelerated tests can

seldom be used to accurately predict the life of a structure. Rather, they more

appropriately give insight in a qualitative fashion to how materials will behave

when subjected to an environment.

In either classification system, the corrosion categories overlap and often

influence each other. Consequently, the classification of corrosion into groups

may be gradually losing its significance as understanding of basic corrosion

mechanisms continues to grow. Because of its intricacy, accelerated testing for

corrosion is difficult to implement, and most types of corrosion do not lend

themselves to prediction of performance through accelerated tests.

Corrosion Testing

Typically, all conventional corrosion testing requires long testing times and is

expensive. There are three major types of corrosion tests: Laboratory, Field,

and Service Testing.

Naturally, service testing provides the highest fidelity results followed by

field testing. However, the service and field tests have limited prospects for

accelerated testing. Accelerated corrosion testing, like any other form of accelerated testing, becomes increasingly more realistic as the laboratory environment approaches that of the service environment. To account for the variation

of corrosion properties with configuration, several other standardized tests are

performed for particular corrosion types, such as uniform attack, pitting, stress

corrosion, and crevice corrosion. There are many ASTM and ISO publications

describing standard test methods for different types of corrosion testing in various atmospheres. Table 3 shows several common tests addressing a variety of

environments.

Before testing

Before implementing any corrosion test, care must be taken when selecting the

corrosive media and preparing the test specimen. Accelerating tests often represent the worst-case scenario, requiring a very aggressive corroding factor.

The onset of corrosion may seriously accelerate damage in an entirely unpredictable manner. Caution must be exercised to make certain the corrosion

mechanism is not altered. Consequently, most accelerated tests should not be

used to predict life or corrosion rates. These tests are typically qualitative, and

the information obtained from them is best used to down-select the most

appropriate materials for use in specific applications.

Selection of Corrosive Media: The corrosion process largely depends

on the corrosive environment. A thorough study of this environment is suggested before planning any corrosion test. In addition to analyzing the characteristics of that environment, make sure that the test does not introduce additional corrosion mechanisms. For instance, inadvertently using a bolt and test

specimen which create a galvanic couple will lead to spurious results. If the

corrosion experiment has an extremely stagnant electrolyte for a crevice corrosion test, the results may not show as aggressive an attack as desired since

the amount of dissolved oxygen in a liquid environment greatly impacts the

corrosion rate. 

Test Specimen Preparation: In addition to carefully selecting the corrosive

environment, the corrosion specimen must be prepared in a fashion indicative

of the service material. Corrosion behavior is influenced by the slightest variation in metallurgical structure and surface preparation - thus care must be taken

while preparing the surface of the testing specimens. Avoid excessive heating

of the surface from grinding operations to remove scale and remove excessive

cold worked surfaces from sample machining, like those found near sheared

surfaces or stamped edges.

Table 3. ASTM Standard Test Methods for Various Environments

Environment causing corrosion Types of Tests

Fresh Water 39 ASTM Standards

Seawater Environments ASTM B117, Salt Spray, Fog Test (Oldest and Most Widely used Cabinet Test) 

General Environments ASTM G31 (Immersion Corrosion Testing), ASTM G50 (Atmospheric Corrosion Testing)

(e.g., atmospheric, galvanic)
Material EASE

14 The AMPTIAC Quarterly, Volume 6, Number 3

Acceleration

Testing does not have to correlate exactly to the service environment as

long as the corrosion mechanism remains the same. However, the results

of accelerated testing should correlate to results from more reliable

sources, e.g., service experience and field testing. The method of accelerating corrosion testing will depend upon the material being examined,

the environment and the type of corrosion mechanism. Several common

methods for acceleration include increasing:

• Aeration for immersion tests

• Temperature (The most common and greatest accelerating factor for

many corrosion mechanisms.)

• Pressure for stress corrosion cracking tests

• Acidity in immersion tests

• The amount of NO2 and SO2 for atmospheric tests

• Relative humidity for atmospheric tests

• Impingement velocity in erosion corrosion tests

• Current in electronic parts prone to corrosion

Additionally for aqueous corrosion, the corroding electrolyte and the

ionic conductivity help determine the rate of corrosion attack. Even when

accelerated, corrosion tests can be inherently slow; hence, testers must

exercise control of these variables. Besides altering the main corrosion

mechanisms, gross variations of all these factors can alter the kinetics of

several intermediate corrosion reactions leading to spurious results.

Since most laboratory corrosion tests are accelerated tests, careful

attention to, and meticulous execution of, their procedure is necessary to

obtain useful results. Standard testing procedures have been set up for the

various laboratory tests. These are described in some detail in Reference

5, and an outline of some of the specific tests and their corresponding

ASTM standards is given in Table 4.

There are many other factors affecting corrosion rates, which lead to

countless test methods. There are fifteen ASTM standards on controlled

humidity tests alone. Moreover, each test includes a range of test conditions. ASTM B 117 allows the concentration of NaCl solution to range

from 3.5% to 20%. The goal is to accelerate the test as much as possible

while keeping the test corrosion mechanism the same as the service corrosion mechanism.

Interpreting the results

In order to correctly interpret the results of any corrosion test, a complete pedigree of material information and testing parameters should

accompany the test results. Variations in the material’s chemical composition, fabrication history, shape and size of the specimen all affect the corrosion rate. For example, the corrosion rate of wrought versus cast alloy

will likely be different. Classifying materials in broad categories such as

“Stainless Steel” or “Aluminum” is a mistake.

The changes in specimen weight versus time are most often used to

calculate corrosion rates. They are the easiest measurement to make.

Additionally, electrochemical polarization methods for measuring corrosion rate are amenable to aqueous corrosion.[4] Other methods, such as

directly measuring a “depth-of-penetration,” can be difficult.

Unfortunately, measuring weight loss is unsuitable for localized corrosion

effects such as pitting, crevice and intergranular attack since total weight

loss can be minimal while local damage can be severe. 

Table 4. Summary of Specific Laboratory Corrosion

Tests and Their Corresponding Standards

Electrochemical Methods ASTM Standard

Electrochemical polarization resistance G-59, D-2776

Electrochemical impedance G-106

Cyclic potentiodynamic polarization G-61

Galvanostatic polarization D-6208

Scratch-repassivation D-6208

Immersion Tests

Total Immersion G-31

Partial immersion G-31

Intermittent immersion G-44

Salt Spray (Fog) Testing

Neutral B-117

Acetic Acid G-85 Annex A1

Cyclic Acidified G-85 Annex A2

Cyclic Seawater Acidified G-85 Annex A3

Cyclic SO2 G-85 Annex A4

Dilute Electrolyte Cyclic Fog Dry G-85 Annex A5

Copper-Accelerated Acetic Acid B-368

Figure 2. Example of How Short-Term Corrosion Test Results

Can Be Misleading.[7]

Extrapolation of

Initical Corrosion

Rate

2-Point Estimate of

Linear Rate

Actual Corrosion

Curve

1 2 4 8 16

Exposure Time, years

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Average Penetration, mm
A DVANCED M ATERIALS AND P ROCESSES T ECHNOLOGY

The AMPTIAC Quarterly, Volume 6, Number 3 15

For general corrosion, (uniform thinning) the corrosion rate is proportional

to the weight loss and inversely proportional to the area, exposure time and

density of the specimen. (Use the original area, not the reduced area, to calculate rates.) Even with general corrosion, care must be taken while testing to

correlate a weight loss to a corrosion rate. For example, many materials produce a scale. If this scale is adherent but does not protect the base metal, it

must be removed before weighing. Adherent scales may exhibit a weight

growth even though the material is severely damaged. Note, the sample

should be carefully examined before cleaning to gain insight into the corrosion

mechanism. For example, adherent deposits or encrustations may cause pitting

or crevice corrosion.

To compound the damage assessment, the corrosion rate often changes

with time due to film formation on the material’s surface. This change in corrosion rate can even undergo cyclical acceleration and deceleration if a scale

thickens and sloughs off. For example, copper immersed in tropical seawater

corrodes at a rate that is proportional to the square root of exposure time and

not linear to it (Figure 2). Curves α and β were calculated from short-term test

data (6-months and 2-year rate respectively). Curve γ is the actual corrosion

rate, which resembles a long-term corrosion rate at short exposure times. On

the other hand, low-carbon steel immersed in a similar environment initially

forms a protective film after which the corrosion rate becomes almost linear

with time. The ASM Handbook on Corrosion[5,6] recommends that at least

three replicate sets of specimens should be tested through exposure at

increased duration, to validate the data.

Pitfalls of Accelerated Testing

With any accelerated testing, caution must be exercised to gain meaningful

results. This is particularly true with accelerated corrosion testing, where the

“pitfalls” are numerous. The following describes some of the more prominent

ones.

Multiple Failure Modes complicate the design of accelerated testing.

New failure modes may appear that can cause the component or the material to degrade or fail. The example mentioned earlier describing scale 

creating sites for pitting or crevice corrosion is a common case of multiple

mechanisms at work. Test specimens which fail by an alternate mechanism not

experienced in the field must be considered invalid.

Misapplied Models are responsible for many of the errors of corrosion

rate and life prediction. Many of the corrosion rate formulas are frequently

misused. Most common among these is the application of predictive equations (often derived from uniform corrosion phenomena) to characterize and

predict the behavior of localized phenomena, such as pitting or crevice 

corrosion. While some debate in this area still exists, one thing is clear: 

uniform corrosion models cannot and should not be applied to localized 

phenomena.

Model Uncertainty is tremendously amplified via extrapolation of results

from the accelerated test. For example, small sample size, sample shape, small

numbers of failures, and large degrees of extrapolation from available data all

combine to create great uncertainty.

Unquantifiable Corrosion factors are major contributors to the uncertainty of models and their frequent misapplication. Certain factors render components much more susceptible to corrosion, such as geometry (crevice 

corrosion, pitting) or welds (selective leaching, SCC). Such effects, while substantial, are not readily quantifiable. Consequently, data from accelerated 

testing cannot provide reliable life predictions in such cases, and is instead 

limited to qualitative assessments.

Multiple Factors Change Degradation when Multiple Time Scale is

Involved. Most failures are the result of several factors. If only one of these factors is accelerated, it may invalidate the contributors of non-accelerated factors. A classic “snake in the grass” is the case of immersing a steel specimen in

water near the boiling point. As the temperature approaches the boiling point

the corrosion rate decreases since the free oxygen in the solution is driven off.

While accelerating one failure mode, a different failure mode (that is usually

the first to appear in the field) is masked.

Acceleration of Specific Variables May Actually Decelerate Failure. For

example, in the case of accelerated testing of a circuit-pack, the test increased

temperature, thus lowering humidity and inhibiting corrosion. The result was

fewer test failures as compared to field conditions.

Prototype Articles for Laboratory Testing May Vary from Production

Units. Materials and parts used to build prototypes may vary from the ones

used in production, partly due to different levels of cleanliness, as well as the

extra attention paid when building them. Test units should be taken from the

field, and should use raw materials from actual production. Manufacturing

conditions should be closely simulated in the accelerated test.

These pitfalls illustrate that, among other difficulties, the field environment is

not as carefully controlled as the laboratory. Because of this, it is difficult to

design an accelerated test that can predict field reliability. Climate, which is

supremely stochastic and essentially random, greatly affects the environmental

conditions, thus rendering test variables highly unpredictable. Some have

attempted to “average” out environmental conditions for accelerated life tests

in the hope of reproducing the variable effects of climate. However, experience has shown that “smearing” environmental effects in accelerated tests

does not provide good prediction of field reliability.

Conclusion

Corrosion is a complex electrochemical process dependent upon a myriad of

factors. Be extremely cautious when devising any accelerated test technique

or using a corrosion rate as gospel for predicting lifetimes. Accelerated corrosion testing is a necessary and powerful tool when used to: (a) help with materials selection as a relative indicator of corrosion resistance, (b) help examine

potential environments for new materials, and (c) help determine corrosion

control strategies of fielded items.

References

[1] Kuruvilla, A.K., Life Prediction and Performance Assurance of Structural

Materials in Corrosive Environments - A State of the Art Report (AMPT-15),

AMPTIAC, 1999.

[2] Fontana, M.G., Corrosion Engineering, 3rd Edition, McGraw-Hill Book

Company, 1986, pp 39-152.

[3] Metals Handbook Ninth Edition, Vol. 13, ASM International, 1987, pp.

79-189

[4] Scully, J.R., Taylor, D.W., “Electrochemical Methods of Corrosion Testing,”

Metals Handbook, Vol. 13, ASM, 1987, pp. 212-228

[5] Metals Handbook Ninth Edition, Vol. 13, ASM International, 1987, pp.

191-317

[6] Baboian, Robert, Editor, “Corrosion Tests and Standards: Application and

Interpretation,” ASTM, 1995.

AMPTIAC
16 The AMPTIAC Quarterly, Volume 6, Number 3

Workshop on Synthetic Aperture 

Radar Tech

10/16/02 - 10/17/02

Redstone Arensal, AL

Contact: Sherry Starling

University of Alabama

Huntsville, AL 35899 

Phone: (256) 876-2628

Email: Sherry.Starling@rdec.redstone. 

army.mil

Web Link: smaplab.ri.uah.edu/SAR02

Refractory Ceramics Division Fall Mtg

10/16/02 - 10/18/02

Pittsburgh, PA

The American Ceramic Society

PO Box 6136

Westerville, OH 43086-6136

Phone: (614) 890-4700

Fax: (614) 899-6109

Email: info@acers.com

Web Link: www.ceramics.org

INTEGRAM - Designing Manufacturable

MEMS for Product Integration

10/29/02

Ulm, Germany

10/30/02

Grenoble, France

11/01/02

Malver, United Kindom

Contact: Gail Messari

Coventor, Inc.

4001 Weston Parkway

Cary, NC 27513

Phone: (919) 854-7500 x102

Fax: (919) 854-7501

Email: gail.massari@coventor.com

Web Link: www.coventor.com

1st Internatl Defence 

Nanotechnology Conf

10/31/02 - 11/01/02

London, United Kingdom

Contact: Alexander Giles

Defence Event Management Ltd.

Southbank House, Black Prince Road

London SE1 7SJ U. Kingdom

Phone: +44 (0) 208 297 8005

Fax: +44 (0) 709 216 2703

Email: agiles@dem-ltd.demon.co.uk

Web Link: www.dem-ltd.com

Workshop on Life Cycle 

Systems Engineering

11/06/02 - 11/07/02

Redstone Arensal, AL

Contact: Sherry Starling

University of Alabama

Huntsville, AL 35899 

Email: Sherry.Starling@rdec.redstone. 

army.mil

Web Link: smaplab.ri.uah.edu/lcse02

Workshop on Lean Manufacturing

11/20/02 - 11/21/02

Redstone Arsenal, AL

Contact: Sherry Starling

University of Alabama in Huntsville

Huntsville, AL 35899 

Phone: (256) 876-2628

Email: Sherry.Starling@rdec.redstone. 

army.mil

Web Link: smaplab.ri.uah.edu/LM02/

DMC-2002 Defense Manufacturing

Conference

12/02/02 - 12/05/02

Dallas, TX

Universal Technologies Corp.

1270 North Fairfield Road

Dayton, OH 45432 

Phone: (937) 426-2808

Fax: (937) 426-8755

Email: utc-mmg@utcdayton.com

Web Link: http://www.dmc.utdayton.com/

Workshop on Nano and Microsystems

Technology and Metrology

12/04/02 - 12/05/02

Redstone Arsenal, AL

Contact: Sherry Starling

University of Alabama in Huntsville

Huntsville, AL 35899 

Phone: (256) 876-2628

Email: Sherry.Starling@rdec.redstone. 

army.mil

Web Link: smaplab.ri.uah.edu/NMTM02/

5th International Military 

Sensing Symposia

12/09/02 - 12/12/02

Gaithersburg, MD

Contact: International MSS Committee

c/o Infrared Information Analysis 

(IRIA) Center

Veridian Systems Division, Inc

PO Box 134008

Ann Arbor, MI 48113-4008 

Phone: (734) 994-1200

Fax: (734) 994-5550

Email: mss@veridian.com

Web Link: www.iriacenter.org

ASIP 2002 (USAF Aircraft Structural

Integrity Program Conference)

12/10/02 - 12/12/02

Savannah, GA

Contact: Jill Jennewine

Universal Technology Corporation

1270 North Fairfield Road

Dayton, OH 45432-2600 

Phone: (937) 426-2808

Fax: (937) 426-8755

Email: jjennewine@utcdayton.com;

Web Link: www.asipcon.com/

ShipTech 2003 - A Shipbuilding

Technologies Information Exchange

01/16/03 - 01/17/03

Biloxi, MS

Contact: Tricia Wright, Event Coordinator

Phone: (814) 269-2567

Email: wright@ctcgsc.org

Web Link: www.ncemt.ctc.com

27th Annual Cocoa Beach Conference 

& Expo. on Advanced Ceramics 

& Composites

01/26/03 - 01/31/03

Cocoa Beach, FL

The American Ceramic Society

PO Box 6136

Westerville, OH 43086-6136

Phone: (614) 890-4700

Fax: (614) 899-6109

Email: info@acers.com

Web Link: www.ceramics.org

High Temple Workshop XXIII

02/10/03 - 02/13/03

Jacksonville, FL

Contact: Jim Sutter

NASA Glenn Research Center

M/S 49-3, 21000 Brookpark Rd

Cleveland, OH 44135

Phone: (216) 433-3226

Fax: (505) 846-8265

Email: james.k.sutter@grc.nasa.gov

Web Link: www.namis.iitri.org

7th International Conference

Commercialization of Military 

and Space Electronics

02/10/03 - 02/13/03

Los Angeles, CA

Contact: Dale Stamps or Leon Hamiter;

Composites Technology, Inc.

Huntsville, AL 35801 

Phone: (256) 536-1304

Fax: (256) 539-8477

Email: dale@cti-us.com

lhamiter@cti-us.com

Web Link: www.cti-us.com

132nd TMS Annual 

Meeting & Exhibition

03/02/03 - 03/06/03

San Diego, CA

Contact: TMS Customer Service; TMS

420 Commonwealth Dr.

Warrendale, PA 15086

Phone: (412) 776-9000 x 253

Fax: (412) 776-3770

Email: csc@tms.org

Web Link: cms.tms.org

Mark Your Calendar
Introduction

Multiple pressures are driving both commercial and military

airframes to stay in service much longer than their designed

service life. Accordingly, inspection requirements to insure aircraft airworthiness have created a need for cost effective NDI

techniques that are accurate, reliable and easy to use.

Studies made it clear that aircraft kept on the ground during long maintenance cycles dramatically increased the

expense of air transport. Maintenance groups not only needed

new and better equipment, they also needed a process to

implement these new technologies into the

maintenance mainstream. Magneto-optic imaging is one such technique, and has gained wide

acceptance for detection of both surface and subsurface defects.

Similar requirements apply to military aircraft

as well if not more so. Many military airframes

are expected to fly up to, and in some cases more

than, twice their design life. Some flight crews

may be operating the same airframes that flew

their fathers or even grandfathers! Inspections for

these aging aircraft must be capable of detecting

surface and subsurface defects, including cracks

and corrosion. This article discusses the development of the magneto-optic technology and its

current inspection applications in both commercial and military aircraft maintenance programs.

An incident involving an Aloha Airlines

Boeing 737, where a large section of the plane’s

skin peeled off during flight, defined the need to

perform careful periodic inspections. It also

spurred companies like PRI Research & Development (PRI)

to bring their budding technologies to the marketplace. One

such technology is the Magneto Optic Imager (MOI), introduced by PRI to the aircraft maintenance world in 1990 at the

Farnborough Air Show in the United Kingdom. Application

of the instrument is shown in Figure 1. It consists of a control

unit, a handheld imager and a head-mounted video display.

Since its introduction, use of the MOI has steadily increased

particularly in areas where it clearly outperformed traditional

methods such as eddy-current spot probes and sliding probes.

Multiple tests have shown the MOI to be a fast and reliable

method of finding surface and subsurface cracks and sometimes corrosion in metal aircraft skins. Since its introduction,

many changes and improvements to the instrument have been

made. These changes have been driven by the changing

inspection priorities and have resulted in the new MOI 308

currently used today (Figure 2). The number of procedures by

major aircraft manufacturers continues to increase, allowing

maintenance personnel to use the instrument in many more

inspections, increasing the cost effectiveness of the instrument

and their acceptance of its place in the NDT arsenal.

The AMPTIAC Quarterly, Volume 6, Number 3 17

W.C.L. Shih, G.L. Fitzpatrick, 

PRI R&D, 25500 Hawthorne Blvd. #2300

Torrance, CA 90505

Figure 1. Using

the MOI*

Figure 2. The MOI 308 System

* All images in this article courtesy PRI Research & Development

308/3

Imager

Personal Video System

Control Unit

308/7 

Imager

Low Frequency

Eddy-current Attachment
The Technology: Its Growth and Change

The MOI uses a combination of an innovative eddy current induction method to induce magnetic fields in defects

and magneto-optics to form images of the magnetic fields

associated with the defects. These real time field images

closely resemble the defects themselves. The MOI is able

to image through paint and other surface coverings in real

time and displays results as visual images on a heads-up

display and/or an ordinary TV monitor. The instrument is

hand-held, portable, requires minimal training, and greatly increases the speed and reliability of inspection. Results

may be videotaped, printed using a video printer or captured digitally.

The magneto-optic/eddy current nondestructive testing

instrument is based in part on the principles of Faraday magneto-optic rotation. In 1845 British physicist Michael Faraday

first observed the effect when linearly polarized light was transmitted through a piece of glass placed in an external magnetic

field. It was observed that magnetic fields affect optical properties of certain materials so that when linearly polarized light is

transmitted through the material in the direction of an applied

magnetic field, the plane of polarization is rotated. This is the

Faraday magneto-optic effect also referred to as the Faraday

rotation, where the amount of rotation is proportional to the

magnetic field H and the path length l. 

In the case of the MOI, the images are formed by distortions

in the magnetic domains of the magneto-optic sensor in

response to the external fields and are relatively insensitive to

the strength of these fields. That is, the images are of a binary

nature, which form with some minimum field strength.

A schematic of the MOI instrument is shown in Figure 3. A

foil carrying alternating current serves as the excitation source

and induces eddy currents in a conducting test specimen.

Under normal conditions, the associated magnetic flux is tangential to the specimen surface. Anomalies in the specimen

generate a normal component of the magnetic flux density,

which the magneto-optic sensor images. The sensor used in the

instrument consists of a thin film of bismuth-doped iron garnet grown on a substrate of gadolinium gallium garnet. These

films exhibit three important properties that are crucial for

generating a magneto-optic image, namely,

1) They possess uniaxial magnetic anisotropy, i.e. they have an

‘easy’ axis of magnetization normal to the sensor surface and

a ‘hard’ axis of magnetization in the plane of the sensor.

2) They possess ‘memory’, i.e. if the magnetization along the

easy axis of magnetization is removed the film will retain

most of the established magnetization.

3) Garnet films possess a relatively large specific Faraday rotation θf which can be in the range of 3 or 4 degrees per

micron of material thickness.

If linearly polarized light is incident normally on the sensor,

the plane of polarization of light is rotated by an angle θ given

approximately by

θ ≈ θf(k

→

•M

→

)l/(|k→||M→|)

Where k

→

is the wave vector of the incident light, l is the sensor

thickness, and M→

is the local state of magnetization of the sensor. Note that M→

is always directed parallel to the ‘easy’ axis of

magnetization. When the reflected light is viewed through the

analyzer, local occurrence of normal magnetic flux is seen as a

‘dark’ or ‘light’ area in the magneto-optic image depending on

the direction of magnetization.

When the MOI was introduced in 1990, inspectors had to

watch images on a monitor that had to be carried with them.

In addition, a second scan of the inspection area was necessary,

because the linear eddy-current induction method produced a

null in the magnetic field in the same direction as that of the

current induction. The original equipment had only one imager with a frequency range of 6.5 kHz to 100 kHz. High interest in corrosion detection spurred development of an imager

utilizing an even lower eddy current induction frequency (to

1.5 kHz to permit deeper field penetration). Further development replaced the monitor with a head mounted display (see

Figure 1), making the inspector completely mobile. In addition, the imager incorporated a rotating current scheme that

eliminated the need for a second scan. Images now reflect a

complete 360 degrees of the area being inspected. 

During the mid nineties, an MOI system directed toward the

inspection of gas turbine engine parts was developed. The result

was the MOI 307, which is significantly smaller and lighter and

was able to operate at higher frequencies for engine materials

such as stainless steel and titanium.

The MOI 308 was introduced in 2000 (see Figure 2). This

system replaces the MOI 303 and MOI 307 with a system

incorporating both imagers with one single control unit. The

new MOI 308 is a modular design approach, allowing inspectors to purchase as much or as little of the equipment necessary

to accomplish the inspections required by various procedures.

It is available in the following configurations:

• The MOI 308/3 (MOI 303 imager) has a frequency range of

1.5 kHz to 100 kHz.

• The MOI 308/7 (MOI 307 imager) has a total frequency

range of 1.5 kHz to 200 kHz. This smaller imager has two

different eddy-current induction attachments. The low frequency unit has a frequency range of 1.5 kHz to 50 kHz and

the high frequency unit has a frequency range of 20 kHz to

200 kHz. They are interchangeable and snap on the imager.

• The MOI 308/37 includes both the MOI 303 and MOI 307

imagers.

18 The AMPTIAC Quarterly, Volume 6, Number 3

Figure 3. Schematic of

the Magneto Optic

Imaging System

Light Source

Polarizer

Analyzer

Induction Foil

Sensor

Bias Coil

Lap Joint
The primary difference between the MOI 308/3 and the

MOI 308/7 is in the size and weight of the imagers and the size

of the imager field of view (FOV). Due to its larger FOV the

MOI 308/3 allows for easier interpretation of subsurface corrosion and permits a larger number of rivets to be seen at once.

The higher frequency range of the MOI 308/7 allows a wider

range of applications that include lower conductivity materials

such as titanium and stainless steel with improved resolution.

Its low weight and small size facilitate its use in restricted areas

as well as general surface and subsurface inspections. Examples

of MOI images for surface cracks using the 303 and 307

imagers are shown in Figure 4.

The real-time imaging capability of the MOI permits rapid

scanning of lap joints for the inspection of spot welds which

was originally performed by tedious spot probe methods at the

Air Force Logistic Centers (ALCs). An example is shown in

Figure 5.

POD Studies for Surface Cracks

The capabilities of the MOI for detecting surface cracks have

been evaluated in independent probability-of-detection (POD)

studies. 

Shown in Figure 6 are POD curves obtained at the

Airworthiness Assurance Nondestructive Inspection Validation

Center (AANC) at Sandia National Laboratories using the MOI

on a set of fatigue crack samples produced to evaluate various

inspection techniques. The four curves to the right were obtained

using the earlier MOI 301 and an eddy current based sliding

probe. The results were published in a Materials Evaluation article[1]. The furthest curve on the left was obtained subsequently

using the newer MOI 303. No data on the same samples have

been obtained with the MOI 307 imager. However, similar

results as for the MOI 303 are to be expected.

The AMPTIAC Quarterly, Volume 6, Number 3 19

Photograph of spot weld sample Cracked spot welds next to fasteners

Uncracked spot welds (not visible) 

next to fasteners

Figure 6. POD Curves for the MOI on Fatigue Crack Samples

Figure 4. MOI 308/3 Image (a) and MOI 308/7 Image (b) of Surface Cracks

Figure 5. MOI Image of Spot Welds. The Larger Split Images are of Fasteners and Smaller Images are

of Defective Spot Welds. Linear Eddy Current Induction Mode is Used.

0 20 40 60 80 100 120

Crack length from rivet shank (mils)

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Probability of Detection

MOI 301 Lab EC Lab MOI 301 Field EC Field MOI 303

(a) (b)
20 The AMPTIAC Quarterly, Volume 6, Number 3

Subsurface Defects

Since the MOI is also eddy current-based, the depth of penetration of electromagnetic waves into conducting inspection materials may be varied by adjusting the eddy current induction frequency. This permits the inspection of conducting materials for

subsurface defects such as fatigue cracks and corrosion. 

Figure 7 shows the MOI image of a third layer-simulated

crack. The crack is made with EDM (electrical-dischargemachining) creating a notch which measures 0.200" from the

5/32" rivet shank. Two sheets of .040" aluminum representing

the outer skin and doubler cover the

third layer .040" aluminum sheet.

Behind the third layer is another

.040" tear strap. The MOI induction

frequency is 3 kHz.

Figure 8 shows the image of corrosion from an actual aircraft belly skin

sample. The piece was cut from the

aircraft after the corrosion was

detected by an MOI from the outside of the aircraft. The skin is .063"

thick with a step to .093".

The worm-like structure seen in

the images are the magnetic domains

in the magneto-optic sensor. They

interact with the magnetic fields

from the defects to form the images.

When the MOI is scanned over the

inspection area, the domain structure

remains stationary while the defect

images move. This facilitates distinguishing subtler defect images from the background. Currently,

image-processing algorithms are being developed at Michigan

State University to perform this function. 

Computational Analysis Support

Since MOI technology is relatively new, its full capabilities have

not been fully explored, but the use of numerical computational methods has been very useful in evaluating some of its

capabilities. An Iowa State University computational nondestructive evaluation (CNDE) group under Prof. L. Udpa

Figure 7. MOI Image of Simulated Third Layer Crack

Figure 8. MOI Image of Corrosion on Actual

Aircraft Belly Skin

Backside of skin 

MOI image from front side of skin

Figure 9. Peak Value of

Magnetic Flux Density

as a Function of

Corrosion Dome Height

for the Single and

Double Layer

Geometry.

Corrosion

Chem-milled Step

Single Layer

Two Layers

(Current MOI)

0 5 10 15 20 25 30 35 40

Depth of Corrosion Dome (%)

Peak Value of Flux Density (Gauss)

2.5

2

1.5

1

0.5

0
The AMPTIAC Quarterly, Volume 6, Number 3 21

(now at Michigan State University) has performed these computations. One exercise was to determine the effect of the second layer of a lap joint on the detectability of corrosion on the

backside of the first layer.

The computations[2] were conducted for corrosion domes of

depths 10%, 20%, 30% and 40% of total thickness at the bottom of an aluminum plate. The model was then modified to

study the effect of a second layer of aluminum in the geometry

below the first layer. The presence of a second layer of aluminum - below the corrosion, provides an additional path for

the induced eddy currents, thereby reducing the magnetic flux

at the sensor placed above the first plate. The peak values of

magnetic field in the presence of the second layer are therefore

reduced by a factor of 2. Figure 9 shows that peak amplitudes

of the magnetic field B

→

z max are a function of height h of the corrosion dome for both single and double layer geometry.

These results are extremely useful in guiding further development of the MOI for the detection of corrosion in lap joints.

This can be accomplished by a combination of increased sensor

sensitivity and/or increase in eddy current induction. Such

improvements are being implemented.

One additional example is the numerical verification of an

inspection used at an Air Force ALC for the detection of circumferential cracks in dimpled countersinks under rivet heads.

Originally, the observation was made that the usual symmetrical MOI image of some rivet sites was distorted using linear

current induction. Upon visual inspection, a circumferential

crack was detected in the countersink region. This effect was

later modeled and verified numerically[3]. The computational

region is shown in Figure 10. The computed magnetic field distribution is shown in Figure 11. The predicted MOI image can

be inferred from Figure 11 by taking a plane cut parallel to the

y-z plane through the field distribution. The resulting cross section will be the MOI image. Due to the asymmetry of the field

distribution, the resulting image will be asymmetric. The actual MOI image is shown in Figure 12.

Procedures

Procedures for using MOI have been written by airlines, maintenance facilities and the military. In particular, Boeing,

Lockheed, Cessna and Bombardier have developed commercial

inspection procedures and the military has written Technical

Orders for KC-135s, B-52s, E-2s, P-3s, and C-141s.

Gulfstream has issued a corrosion inspection procedure.

A recently issued procedure for the MOI uses traditional

eddy current spot probe procedures for the detection of hidden

cracks in the skin along the chem-milled (doubler) edge on the

back side of the outer skin. It was found that the MOI is significantly faster and easier to use. Boeing personnel estimate

that using the MOI for the chem-mill crack inspections would

be faster by at least a factor of four including verification of

MOI-detected cracks with a spot probe. Actual on-plane tests

proved even faster.

The MOI permits the inspector to simultaneously locate the

doubler edge as well as scan for subsurface cracks along the

doubler edges from the front side of the skin. On the other

hand, using a spot probe, the inspector would first have to trace

out the doubler edge, mark the location on the surface and then

use the spot probe to inspect for cracks along the marked edge.

This would be a very tedious procedure.

There have also been some creative uses of the instrument,

not detailed in manufacturer’s procedures. Considerable success

Figure 10. Computational Grid for Dimpled Countersink with

Circumferential Crack

Figure 11. Magnetic Field

Distribution for Dimpled

Countersink with Crack

Figure 12. MOI Image of Cracked Countersink (image on right)
22 The AMPTIAC Quarterly, Volume 6, Number 3

has been achieved in using the MOI for screening old 707s for

conversion to JSTARS specifications for the Air Force. The

MOI was used to rapidly identify aircraft unfit for use. This

resulted in significant savings by avoiding unnecessary, expensive repairs. According to Bill Pember with NorthropGrumman in Melbourne, Florida, initially these aircraft were

evaluated primarily through visual screening and documentation review. They often required tremendous rework and repair

to bring them up to the required level of quality and structural

integrity. The cost associated with this labor-intensive task was

difficult to accept. The newly developed philosophy (1998)

which utilizes MOI in the assessment of aging aircraft has

reduced this problem and significant savings are now being

realized.[4]

R&D activities and other applications

Developing improvements to the MOI system is an on-going

activity. Many of the improvements have been made as

upgrades to existing units to minimize equipment obsolescence. Current activities include an FAA-sponsored research

program to improve the magneto-optic sensor’s sensitivity and

to develop image processing techniques to improve and automate defect recognition.

PRI has also cooperated with NASA under a Space Act

Agreement. The intent is to develop a prototype reader for

Data Matrix symbols (used for direct parts marking (DPM))

covered by paint and other coverings.

Summary

The MOI technology represents a relatively new application of

magneto-optics to NDT. It retains many attributes associated

with eddy current testing with obvious advantages of providing a

visual display of the results using only analog methods. In this

article, we have summarized the development of the MOI since

its introduction to the NDT community a decade ago. Although

the instrument is now widely used by both commercial and military installations to inspect for surface and subsurface defects,

the route to general acceptance and use by the community has

been long and serendipitous. As yet, there is no well-defined

process or criteria by which new technologies are introduced and

accepted into the marketplace. The OEM on whose aircraft the

instrument will be used must approve use of the instrument for

specific inspections. If no general procedures exist, then each airline must receive specific approval for its use. The difficulty is the

development of general criteria applicable to all possible inspections of a multiple variety of structural designs.

For more information 

The preceding article describes an NDT technique aiding in

the search for corrosion and other flaws on aging aircraft. While

the article details specific materials-related attributes of this system’s design and implementation, this is just one of many techniques available in the large field of NDT The interested reader is encouraged to consult our colleagues at the

Nondestructive Testing Information Analysis Center (NTIAC,

one of 13 Defense Technical Information Center IACs like

AMPTIAC) who specialize in this field. NTIAC can provide

more information on NDE techniques, systems and standards,

as well as links to other resources in the NDE community. 

NTIAC can be reached at www.ntiac.com, or 1-800-

NTIAC39.

References

[1] “The Validation Process as Applied to the MagnetoOptic/Eddy Current Imager (MOI),” Vanessa Brechling

(Northwestern University) and Floyd Spencer (Sandia National

Laboratories), Materials Evaluation, July, 1995, Vol. 53, No. 7,

pp. 815-818.

[2] “Finite-Element Predictions of MOI Performance for

Application to Aging Aircraft Inspection” Lalita Udpa, in

Center for NDE News, Iowa State University, Vol. 10, Issue 3,

Winter 2000.

[3] Private communications from Professor L. Udpa and Dr. L.

Xuan of Michigan State University.

[4] Private communications from Bill Pember, NorthropGrumman, Melbourne, FL.

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The AMPTIAC Quarterly, Volume 6, Number 3 23

AMPTIAC Directory

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TECHNICAL MANAGER/COTR

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Staff Specialist, Materials & Structures

ODUSD(S&T)/Weapons Systems

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Email: lewis.sloter@osd.mil

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Email: mrozga@dtic.mil

ASSOCIATE COTRS

CERAMICS, CERAMIC COMPOSITES

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Naval Research Laboratory

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(202) 767-2264, Fax: (202) 404-8009

Email: sanday@anvil.nrl.navy.mil

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ORGANIC MATRIX COMPOSITES

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US Air Force

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Wright-Patterson AFB, OH 45433-7702

(937) 656-6052, Fax: (937) 255-2945

Email: roger.griswold@wpafb.af.mil

ENVIRONMENTAL PROTECTION

& SPECIAL FUNCTION MATERIALS

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Naval Research Laboratory

4555 Overlook Ave., S.W. Code 6100

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Email: murday@ccsalpha3.nrl.navy.mil

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Email: dbrumbaugh@iitri.org

Overworked? Overloaded? 

Could you use some materials engineering help? 

AMPTIAC can provide answers to materials-related technical questions. 

Here’s how it works: You contact our inquiry manager with the problem. The

inquiry manager discusses the problem with you to make sure we understand exactly what

you need. He then assigns the task to an AMPTIAC technical expert with knowledge and

experience of the discipline in question. 

AMPTIAC maintains the DOD’s knowledge base in advanced materials; nearly 220,000 technical reports addressing

all classes of materials. Our database contains information on properties, durability, applications, processes, and more.

Plus if we don’t find it in our resources, we also have direct access to NASA and DOE databases. With this tremendous

amount of data, our engineering staff can save you time and money by quickly providing you with off-the-shelf information or technical solutions that directly meet your needs. 

For smaller inquiries and bibliographic searches we can provide you some information free of charge. Larger efforts are

on a cost-reimbursable basis but under no circumstances do we begin work before you accept our quote and issue us a

purchase order. For more information on how we can help you, please contact AMPTIAC’s Inquiry Services Manager,

Mr. David Brumbaugh, at (315) 339-7113. 

A Recent Example 

A government contractor asked us to locate and compile properties of carbon fiber composites at cryogenic temperature.

In less than 2 weeks we: 

• performed a literature review • identified 162 relevant technical reports • reviewed the reports and extracted 

appropriate data • organized 152 pages of data in a binder • and cross-linked the data to a searchable spreadsheet 

The resultant data book provided the contractor with valuable information they needed in their effort to design a satellite structure. 

IITRI Personnel
MaterialEASE: 

Tips and Pitfalls 

of Corrosion Testing

MOI System Allows Examiners 

to “See” Defects in Metal

Materials Data Exchange 

Made Easier on the Web

... and more!

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