CONTAINERLESS

PROPERTY

HIGH TEMPERATURE

MEASUREMENTS

FINAL TECHNICAL REPORT

December 6, 1991

NASA Contract No. NAS8-37427

Contract Period: September 21, 1988 - October 31, 1991

by

Paul C. Nordine, J. K. Richard Weber,

Shankar Krishnan, and Collin D. Anderson

for

Microgravity Sciences and Applications Program

Technical Contract Monitor: Dr. M. B. Robinson/ES-74

NASA-George C. Marshall Space Flight Center

Marshall Space Flight Center, Alabama 35812

(NA_A-CR-I_4271) CONTATNERLESS HTGH

TEMPERATURE PROPERTY MEASUREMENTS Final

Rpport, 21Sep. 1988 - 31 Oct. I_QI

(Tntersonics) 14 p CSCL 22A

G3129

N92-I_196

3453 Commercial Avenue Northbrook, IL 80062-1818 708/272-1772 Phone 708/272-9324 FAX
PREFACE

This is the final technical report for NASA Contract No.

NAS8-37427 for research conducted at Intersonics, Incorporated

during the period September 21, 1988 - October 31, 1991. It

continued work directed by Dr. Paul Nordine in two previous NASA

projects, Contract No. NAS8-34383 at Yale University and Grant No.

NAGS-465 at Midwest Research Institute. Technical questions may be

directed to Dr. Nordine. Administrative questions may be directed

to Ms. Betty Brewer, Contracts Manager.

Approved for

INTERSONICS, INCORPORATED

President

December 6, 1991
TABLE OF CONTENTS

io

2.

g

4.

5.

INTRODUCTION AND SUMMARY ................

RESEARCH RESULTS .................

2.2 Hybrid Aerodynamic-Electromagnetic Levitation

REFERENCES .......................

PUBLICATIONS, REPORTS & PRESENTATIONS .........

APPENDIX ........................

1

2

2

3

5

7

10

Figure i Hybrid Aerodynamic-Electromagnetic Levitation

Apparatus .....................

4
L I F

.1. INTRODUCTION AND SUMMARY

Containerless processing in the low-gravity environment of space

provides the opportunity to increase the temperature at which well

controlled processing of and property measurements on materials is

possible. The thermodynamic inevitability of container

interactions [i] may thus be defeated.

This project was directed towards advancing containerless

processing and property measurement techniques for application to

materials research at high temperatures in space. The work was

carried out in the ground-based containerless processing facility

at Intersonics, Incorporated. The experimental work served three

major goals, to: (i) apply new techniques to containerless property

measurements, (ii) perform property measurements on materials of

interest to NASA-supported scientists and (iii) extend the limits

of ground-based containerless techniques.

Containerless conditions were achieved by electromagnetic

levitation of liquid and solid metals and aerodynamic levitation of

solid non-metals. These techniques were used in combination with

cw CO 2 laser beam heating. Optical techniques used for non-contact

property measurements were optical pyrometry for temperature, laser

induced fluorescence for gaseous species concentrations, and laser

polarimetry for optical properties and spectral emissivities.

Containerless high temperature material property investigations

which have been completed in this work include measurements of the

vapor pressure, melting temperature, optical properties, and

spectral emissivities of solid boron [2,3]. The reaction of boron

with nitrogen was also investigated by laser polarimetric

measurement of boron nitride film growth [3]. The optical

properties and spectral emissivities were measured [4-7] for solid

and liquid silicon, niobium, and zirconium; liquid aluminum and

titanium; and liquid Ti-AI alloys of 5-60 atomic percent titanium.

Alternative means for non-contact temperature measurement in the

absence of material emissivity data were evaluated [8]. In

addition, the application of laser induced fluorescence for

component activity measurements in electromagnetically levitated

liquids was investigated, and the feasibility of a hybrid

aerodynamic-electromagnetic levitation technique was demonstrated.

Thermodynamic criteria for cleaning a number of materials were

evaluated [5-7,9]. Clean metal surfaces were achieved for AI, Si,

Ti, Nb, Zr, and Ti-AI alloys. The purification of Zr [7] was

particularly difficult due to the high temperature required to

decompose the nitride. The purification of the ambient gas by

reaction with metal vapor was also demonstrated and confirmed by

laser induced fluorescence (LIF) measurements. Titanium vapor was

detected by LIF only if its vaporization rate calculated from vapor

pressure data exceeded the measured flow rate of gaseous impurities

in the inert gas and from outgassing or leaks.

1
• The research conducted in this project had important implications

for several other investigations. The Ti-AI alloy emissivity data

allowed Anderson et al. [10-12] to measure the true degree of

undercooling that could be achieved in these alloys [ii] and to

obtain accurate liquidus temperature measurements [12] in this

system. Substantial errors in the previous liquidus data were

found in their work. Also, in work that was supported by the Air

Force and by Los Alamos National Laboratory, it was possible to

extend the optical property investigations to measurements on

liquid aluminum oxide [13] and levitated liquid uranium metal [14].

This report concludes a sequence of three NASA-sponsored projects

in Containerless Property Measurements. The two earlier projects

were conducted at Yale University and at Midwest Research

Institute. The present work benefited greatly from developments in

polarimetric measurement of optical properties that originated at

Rice University [15,16], and also included collaborative work with

scientists from Vanderbilt University on the Ti-AI system [6,10-

12]. NASA-supported work in the area of containerless processing

and property measurements is continuing at Intersonics in two new

projects funded under the recent NRA on Containerless Microgravity

Experimentation.

2. RESEARCH RESULTS

Much of the research performed under this contract has been

reported in the literature [2-9,17]. Abstracts for papers in

preparation [6,7] are given in the appendix. In addition two sets

of feasibility experiments were conducted which are described

below.

2.1 Alloy Component Activity Measurements

Feasibility experiments were performed to evaluate the

measurement of component activities and vapor pressures by laser

induced fluorescence over electromagnetically levitated liquid

alloys. Since emissivities of liquids can be measured with high

accuracy via polarimetry, their absolute temperatures can be

determined. Then activity values can be measured as the LIF

intensity ratio over the alloy and its pure components at the same

temperature.

Spatially resolved LIF intensity measurements are required in

these experiments because the atom concentrations in the gas phase

decrease with distance from the specimen surface. True equilibrium

vapor pressures and activities are obtained only by extrapolating

LIF intensity measurements to the specimen surface. The spatially

resolved measurements proved to be impossible in the tightly wound

coils necessary to levitate liquid titanium. They could be made in

more open EM coil configurations, which might be possible if

increased electromagnetic power was available. A 5 kW EM generator

was used in this research.

2
The feasibility of an alternative technique for using more

open EM coils was investigated, i.e. , the combination of

aerodynamic and electromagnetic levitation. This is described in

the next section.

2.2 Hybrid _erodynamic-Electromagnetic Levitation

The simultaneous use of aerodynamic and electromagnetic

levitation offers the ability to extend the operating conditions

available with either levitation technique. Aerodynamic forces

reduce the EM field strength requirements and (i) allow reduced

temperatures to be obtained and (ii) more open coil configurations

consistent with the requirements of property measurement

experiments. At the same time, electromagnetic centering and

shaping forces stabilize the aerodynamic levitation of liquids.

This has already been demonstrated in early work [18] to

investigate electromagnetic heated and aerodynamically levitated

liquid aluminum and uranium. The early work used a conicallyshaped levitator which limited optical access to the specimen even

though the EM coil did not. In the present feasibility study, the

use of free jet levitation in combination with a more open EM coil

architecture was investigated.

The apparatus is illustrated in Figure i. Experiments were

conducted with 3 mm diameter aluminum spheres. The spheres were

levitated in the gas jet and conditions adjusted to center the

specimen in the EM coil. Then the EM power was turned on and the

specimens were heated.

Results from the feasibility experiments were as follows:

O With a 5 mm i.d. cusp coil, the specimen could not be

positioned in the coil gap which was about 3mm. The specimen

levitated either above or below but not within the coil as the

levitation gas flow rate was changed. It should be possible

to levitate in the gap if the gap distance were increased.

O The specimen could be inserted into a coil of i0 mm i.d. by

adjusting the levitation gas flow rate.

O Stable levitation continued as the specimen was EM heated to

the melting point. The specimen tended to move down in the

coil as its temperature increased and could be raised by

decreasing the gas flow rate.

O Rapid oscillations of the solid specimens occurred during

heating unless the gas jet and EM coil were carefully centered

on the same axis.
(

-1I

_ -r"I

E3n

Om

LI_

13_EU

(3
.O Upon melting, specimen stability was maintained for several

seconds, it then became unstable. Small changes in the coil

separation, centering, and other adjustments influenced the

rate at which instabilities developed.

o Most stable levitation and melting behavior was achieved with

the most open coils with inside diameters up to i0 mm and coil

gaps up to 6 mm.

Hybrid aerodynamic-electromagnetic levitation of liquid metals

was demonstrated to provide the basis for new experiments. Two

qualities of the technique which extend existing capabilities are:

(i) levitation with an open coil architecture, and (ii) extension

to lower temperatures of the temperature range over which liquids

can be levitated.

Levitation in an open coil will enable spatially resolved LIF

measurements to be made up to the specimen surface. When the

operating protocols for stable levitation of liquid metals are

established, alloy activity and thermodynamic property measurements

can be conducted on liquid alloys.

3. REFERENCES

I , P.C. Nordine and R.A. Schiffman, "Containerless Laser-Induced

Fluorescence Study of Vaporization and Optical Properties for

Sapphire and Alumina", Adv. Ceram. Mats., _, 478 (1988).

. P.C. Nordine, J.K.R. Weber, S. Krishnan and R.A. Schiffman,

"The Vapor Pressure and Sublimation Enthalpy of Pure Boron,"

High Temperature Science, 1991, in press.

S. Krishnan, P.C. Nordine, J.K.R. Weber and R.A. Schiffman,

"Optical Properties and Melting Point of Pure Boron," High

Temperature Science, 1991, in press.

J.K. Richard Weber, S. Krishnan, R.A. Schiffman and Paul C.

Nordine, "Optical and Thermodynamic Property Measurements of

Liquid Metals and Alloys," Advances in Space Research, ii, 43

(1991) .

. S. Krishnan, J.K.R. Weber, P.C. Nordine, R.A. Schiffman, R.H.

Hauge and J.L. Margrave, "Spectral Emissivities and Optical

Properties of Liquid Silicon, Aluminum, Titanium, and Niobium

at 632.8 nm", High Temperature Science, 1991, in press.

. S. Krishnan, C.D. Anderson, J.K.R. Weber, P.C. Nordine, W.H.

Hofmeister, and R.J. Bayuzick, "Spectral Emissivities and

Optical Properties in the Titanium -Aluminum System", in

preparation.

5
.7. S. Krishnan, C.D. Anderson, J.K.R. Weber, P.C. Nordine,

"Spectral Emissivities and Optical Properties of Solid and

Liquid Zirconium", in preparation•

• P.C. Nordine, S. Krishnan, J.K. Richard Weber, and Robert A.

Schiffman,"Non-Contact Temperature Measurement," Advances in

Space Research, 11, 170 (1991).

• J.K. Richard Weber, Shankar Krishnan and Paul C. Nordine, "The

Use of Containerless Processing in Researching Reactive

Materials," J. Mets. 43, 8 (1991)•

I0. C.D. Anderson, Phase Stability, Metastability, and

Solidification Kinetics in Binary Ti-AI, Ph.D. Dissertation,

Vanderbilt University, May, 1991.

II. C.D. Anderson, W.H. Hofmeister and R.J. Bayuzick,

"Solidification Kinetics and Metastable Phase Formation in

Binary Ti-AI, " submitted to Met. Trans

12.

13.

C.D. Anderson, W.H. Hofmeister and R.J. Bayuzick, "Liquidus

Temperatures in the TiAI System", in preparation.

S. Krishnan, J.K.R. Weber, R. Schiffman and P. Nordine,

"Refractive Index of Liquid Aluminum Oxide at 0.6328 _m," J.

Am. Cer. Soc. 74, 4 (1991).

14. S. Krishnan, J.K.R. Weber, P.C. Nordine and R.I. Sheldon,

"Spectral Emissivity, Optical and Thermodynamic Properties of

Levitated Liquid Uranium at High Temperatures", in

preparation.

15.

16.

S. Krishnan, "Thermophysical and Optical Property Measurements

of ElectromagneticallyLevitated Liquid Metals", Ph.D Thesis,

Rice University, Dec. 1988.

S. Krishnan, G.P. Hansen, R.H. Hauge, and J.L. Margrave,

"Spectral Emissivities and Optical Properties of

Electromagnetically Levitated Liquid Metals as Functions of

Temperature and Wavelength," High Temperature Science, 2917,

(1990).

17. J.K.R. Weber, R.A. Schiffman, S. Krishnan and P.C. Nordine,

"Containerless Processing and Property Measurements of High

Temperature Liquids and Solids" Proc. VIIth European Symposium

on Materials and Fluid Sciences in Microgravity, Oxford, UK,

Sept. 1989.

18. D.A. Winborne, P.C. Nordine, D.E. Rosner and N.F. Marley,

"Aerodynamic Levitation Technique for Containerless High

Temperature Studies on Liquid and Solid Samples", Met. Trans.

7B, 711, 1976.
.4, PUBLICATIONS, REPORT8 & PRESENTATIONS

"Vapor Pressure and Spectral Emissivity of Boron," P. C. Nordine,

R. A. Schiffman, J. K. R. Weber, and S. Krishnan, pres. at the

Sixth Int. Conf. on High Temperatures - Chemistry of Inorganic

Materials, Gaithersburg, MD, 3-7 April 1989.

"Spectral Emissivities and Optical Constants of Electromagnetically

Levitated Liquid Metals as Functions of Temperature and

Wavelength," S. Krishnan, R.H. Hauge, and J.L. Margrave, Proc.

Second Noncontact Temperature Measurement Workshop, NASA Publ. JPL89-16, Jun 1989.

"Containerless Processing and Property Measurements of High

Temperature Liquids and Solids" J.K.R. Weber, R.A. Schiffman, S.

Krishnan and P.C. Nordine, Proc. VIIth European Symposium on

Materials and Fluid Sciences in Microgravity, Oxford, UK, Sept.

1989, pp. 639-643.

"Emissivities and Optical Constants of Electromagnetically

Levitated Liquid Metals as Functions of Temperature and

Wavelength," S. Krishnan, G.P. Hansen, R.H. Hauge, and J.L.

Margrave, Sixth IUPAC Proc. Washington, DC, April 1989, High Temp.

sci. 26, 143 (1990).

"optical Property Measurements as a Diagnostic Tool in

Containerless Processing," S. Krishnan, J. K. R. Weber, P. C.

Nordine, and R. A. Schiffman, Proc. Containerless Experimentation

in Microgravity Workshop, JPL, Pasadena, CA, 17-19 Jan. 1990, pp.

237-241.

"NCTM of Liquids at High Temperatures Using Polarization

Techniques," S. Krishnan, J. K. R. Weber, P. C. Nordine, and R. A.

Schiffman, Proc. Containerless Experimentation in Microgravity

Workshop, JPL, Pasadena, CA, 17-19 Jan. 1990, pp. 379-384.

"Containerless Processing of Amorphous Ceramics", J. K. R. Weber,

S. Krishnan, P.C. Nordine and R.A. Schiffman, Proc. Containerless

Experimentation in Microgravity Workshop, JPL, Pasadena, CA, 17-19

Jan. 1990, pp. 385-390.

"Optical Properties of Liquid Niobium, Titanium, and Zirconium," S.

Krishnan, R. A. Schiffman, P. C. Nordine, J. K. R. Weber, R. H.

Hauge, J. L. Margrave and W. Hofmeister, pres. at Gordon Research

Conference on High Temperature Chemistry, Meriden, NH, 23-27 July

1990.
"Optical Properties of solid and Liquid Metals at Elevated

Temperature," S. Krishnan, J. K. R. Weber, P. C. Nordine, and R. A.

Schiffman, Pres. at the Symp. on High Temp. Chemistry, 178th

Electrochemical Society Meeting, Seattle, WA, 14-19 Oct. 1990

"Polarization Techniques for Temperature Measurement and Control in

Materials Processing," S. Krishnan, J. K. R. Weber, P. C. Nordine,

and R. A. Schiffman, Pres. at the Symp. on High Temp. Chemistry,

178th Electrochemical Society Meeting, Seattle, WA, Oct. 14-19 Oct.

1990

"Spectral Emissivities and Optical Properties of

Electromagnetically Levitated Liquid Metals as Functions of

Temperature and Wavelength," S. Krishnan, G.P. Hansen, R.H. Hauge,

and J.L. Margrave, High Temp. sci. 29, 17-52 (1990).

"Optical and Thermodynamic Property Measurements of Liquid Metals

and Alloys," J.K. Richard Weber, S. Krishnan, R.A. Schiffman and

Paul C. Nordine, Advances in Space Research, Ii, 43 (1991).

"Non-Contact Temperature Measurement," P.C. Nordine, S. Krishnan,

J.K. Richard Weber, and Robert A. Schiffman, Advances in Space

Research, ii, 170 (1991).

"The Use of Containerless Processing in Researching Reactive

Materials," J.K. Richard Weber, Shankar Krishnan and Paul C.

Nordine, J. Metals 43, 8 (1991).

"Containerless Processing of Refractory Metals,", J.K.R. Weber, S.

Krishnan, and P.C. Nordine Proc. TMS Refractory Metals Symp., TMS

1991.

"Optical Properties and Melting Point of Pure Boron," S. Krishnan,

P.C. Nordine, J.K.R. Weber and R.A. Schiffman, High Temperature

Science, 1991, in press.

"The Vapor Pressure and Sublimation Enthalpy of Pure Boron," P.C.

Nordine, J.K.R. Weber, S. Krishnan and R.A. Schiffman, High

Temperature Science, 1991, in press.

"Spectral Emissivities and Optical Properties of Liquid Silicon,

Aluminum, Titanium, and Niobium at 632.8 nm," S. Krishnan, J.K.R.

Weber, P.C. Nordine, R.A. Schiffman, R.H. Hauge and J.L. Margrave,

High Temperature Science, 1991, in press.

"Spectral Emissivities and Optical Properties in the Titanium -

Aluminum System," S. Krishnan, C.A. Anderson, J.K.R. Weber, P.C.

Nordine, W.H. Hofmeister, and R.J. Bayuzick, in preparation.

8
."Spectral Emissivities and Optical Properties of Solid and Liquid

Zirconium", S. Krishnan, C.A. Anderson, J.K.R. Weber, P.C. Nordine,

in preparation.

"High Temperature Containerless Materials Research", P.C. Nordine,

J.K.R. Weber and S. Krishnan, pres. at the High Temperature

Materials Properties VII Conference, Orleans, France, 15-21 June

1991.

"Liquidus Temperatures and Liquid Phase Emissivities in the Ti-AI

System", C.D. Anderson, S. Krishnan, W.H. Hofmeister, R.J.

Bayuzick, J.K.R. Weber, P.C. Nordine, pres. TMS Fall Meeting,

Cincinnati, Ohio, September 1991.

9
APPENDIX

ABSTRACTS OF PAPERS IN PREPARATION

Spectral Emissivities and Optical Properties in the Titanium -

Aluminum System

S. Krishnan, C.D. Anderson, J.K.R. Weber, P.C. Nordine,

W.H. Hofmeister, and R.J. Bayuzick

The spectral emissivities, refractive indices, and extinction

coefficients of solid, liquid, and supercooled liquid titaniumaluminum alloys were measured vs temperature by He-Ne laser

polarimetry at 632.8 nm. The experiments were carried out under

containerless conditions using electromagnetic levitation and

heating supplemented by CO 2 laser beam heating. Small temperature

dependencies to the normal spectral emissivities were observed for

all the alloy compositions that were studied. The undercooled

melts exhibited virtually constant spectral emissivities but

emissivities varied slightly with temperature for the stable

liquids. The optical properties and spectral emissivities of the

liquid phase varied smoothly with composition. The spectral

emissivities decreased by a factor of six and the optical constants

differed two-fold between pure liquid titanium and aluminum. The

spectral emissivity vs composition at 1800K showed a maximum near

the equiatomic Ti-AI composition and a minimum near pure liquid

aluminum. Up to 300K undercooling of the liquid was observed for

near-equiatomic compositions.

i0
w i

Spectral Emissivities and Optical Properties of Solid and Liquid

Zirconium

S. Krishnan, C.D. Anderson, J.K.R. Weber, P.C. Nordine

The spectral emissivities, refractive indices, and extinction

coefficients of solid, liquid, and supercooled liquid zirconium

were measured vs temperature by He-Ne laser polarimetry at 632.8

nm. The experiments were carried out under containerless

conditions using electromagnetic levitation and heating

supplemented by CO 2 laser beam heating. No significant differences

in the normal spectral emissivities and optical properties were

observed for these materials over the 2000 - 2128K temperature

range for the solid and 2000 - 2650K for the liquid. The values e

= 0.35, n - 2.85, and k - 4.20 were determined for the emissivity,

index of refraction, and extinction coefficient, respectively. The

emissivity value agrees with selected results from the recent

scientific literature.

ii