ORNL-TM-3609.txt

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UNION CARBIDE

 

 

 

OAK RIDGE ‘NATIONAL LABORATORY

operated by
CORPORATION ¢ NUCLEAR DIVISION

for the

U.S. ATOMIC ENERGY COMMISSION

ORNL- TM - 3609

A STUDY OF THE ADHERENCE OF TUNGSTEN AND MOLYBDENUM COATINGS

J. |. Federerand L. E., Poteat

THIS DOCUMENT co

NFIRM
DIVISION OF G ASED oS
BY IFICATION

DATE " bl

RE269

NOTICE This document contains information of o preliminary nature
ond was prepared primarily for internal use at the Ouk Ridge National

Loboratory. It is subject 1o revision or correction and therefore does

not represent a final report.

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usefulness of any information, apparatus, product or process disclosed, or
represents that its use would not infringe privately owned rights,

 

 
 

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Contract No. W-7405-~eng-26

METALS AND CERAMICS DIVISION

ORNL~-TM~3609

Con #7204 o~- 3

A STUDY OF THE ADHERENCE OF TUNGSTEN AND MOLYBDENUM COATINGS

J. I. Federer and L. E. Poteat

Paper to be presented at the
Third International Conference
Chemical Vepor Deposition,
Salt Lake City, Utah,
April 2427, 1972,

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on

 

to be published in
proceedings of meeting

 

— NOTICE
This report was prepared as an account of work

| sponsored by the United Staies Government. Neither

the United States nor the United States Atomic Energy

- Commmission, nor any of their employees, nor any of

. | their contractors, subcontractors, or their employees,

DECEMBER 1971

 

makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, com-
pleteness or usefulness of any information, apparatus,
product or process disclosed, or represents that its use

{ would not infringe privately owned rights,

 

OAK RIDGE NATIONAL IABORATORY
Oek Ridge, Tennessee 37830
operated by '
UNION CARBIDE CORPORATION
for the
U.S. ATOMIC ENERGY COMMISSION

TS ROSUMERT IS UMLK |

 
 

DISTRIBUTIGH OF

 
 

 

 

 

 

 
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CONTENTS
Abstract .
Introduction . .
Coating Technique
Materials . . . . . . . . . . . . ..
Substrate Reactions . . . .
Preliminary Coating Results . . . . .

Coating Adherence

Thermal Cycle Tests .

Bend Tests

Tensile Tests .
Conclusions
Acknowledgments

References . . .

 

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A STUDY OF THE ADHERENCE OF TUNGSTEN AND MOLYBDENUM COATINGS

J. I. Federer and L. E. Poteat

ABSTRACT

Tungsten and molybdenum coatings on iron- and nickel-base alloys are being
investigated as a potential solution to the corrosion problem in Molten Salt
Breeder Reactor reprocessing equipment. The adhesion of coatings applied by
hydrogen reduction of WFg and MoFe¢ has been evaluated. Displacement reactions
between iron and chromium in the iron-base alloys and the WFg and MoF, pre-
vented adhesion of the coatings. A thin nickel plate diffusion bonded to the
iron-base alloys minimized side reactions and solved the adhesion problem.
Both tungsten and molybdenum coatings remained intact after repeated thermal
cycling between 25 and 600°C and during a spiral bend test. Tungsten coatings
had tensile bond strengths up to 35,000 psi.

 

INTRODUCTION

The purpose of this study was to develop a corrosion-resistant coating for
Molten Salt Breeder Reactor fuel reprocessing equipment. The reprocessing
scheme involves the extraction of uranium, protactinium, and rare-earth fission
products from the molten fluoride salt fuel at 500 to 700°C with liquid bismuth
containing lithium and thorium as reductants. The desired characteristics of
the material of construction of the reprocessing equipment include fabricabil-
ity, strength, resistance to air oxidation, and resistance to attack by liquid
bismuth~lithium-thorium solution and molten fluoride salts. Alloys based on
iron and nickel have many of the properties required for this application, but
lack resistance to mass transfer in bismuth. On the other hand, tungsten and
molybdenum, and certain alloys of these metals are resistant to corrosion by
liquid bismuth, but are much more difficult to fabricate. A potential sclution
to this problem would be coatings of corrosion-resistant tungsten or molybdenum
on the more easily fabricated iron- and nickel-base alloys.

In order to investigate this potential solution, tungsten and molybdenum coat-
ings were deposited on several iron- and nickel-base alloy substrates. The
adherence of the coatings to the substrates was evaluated by thermal cycling
tests, bend tests, and tensile tests to determine their suitability for
protecting the substrates.

COATING TECHNIQUE

Tungsten and molybdenum coatings were deposited by hydrogen reduction of WFg
and MoFg¢, respectively. Deposition temperatures were typlcally 500 to 600°C
for tungsten and 800 to 900°C for molybdenum at & pressure of 5 to 10 torr.
The specimens were coupons (3/4 by 2 in.) or strips (3/4 by 10 in.). These
were positioned on edge In a furnace-heated tube and coated on both surfaces.
 

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The substrate materials included in this study are shown in Table 1.

MATERIAIS

These

materials are representative of the numerous iron- and nickel-base alloys of

commercial importance.

The average coefficients of thermal expansion over the

temperature range 25 to 600°C are compared with tungsten and molybdenum in

Table 1.

The closest match in thermal expansion between coating and substrate

is obtained with the iron-nickel alloys, followed closely by the ferritic
stainless steels (types 405, 430, and 442), while the greatest mismatch is

At the outset of this study, the dif-
ference in thermal expansion between coating and substrate was considered to
be a critical factor influencing adherence.

obtained with type 304 stainless steel.

 

 

 

Table 1. Materials Included in Coating Study
Nominal Composition, % a
Materials Fe Cr  Ni W Mo (u-in. in.”? °c"1)
Steel 99+ 14.5
Type 304 stainless steel 74 18 8 18.5
Type 405 stainless steel 88 12 11.2
Type 430 stainless steel 84 16 11.2
Type 442 stainless steel 80 20 11.7
Fe-35% Ni 65 35 10.0
Fe-40% Ni 60 40 10.0
Fe—45% Ni 55 45 10.0
Fe-50% Ni 50 50 10.0
Nickel 99+ 13.3
Hastelloy C 5 15 58 4 16 13.3
Inconel 600 9 16 75 15.3
Monel 1.5 67 17.8
Hastelloy N 5 7 70 16 .1
Tungsten 100 4.6
Molybdenum 100 5.9

 

8a1so contains 30% cu.

SUBSTRATE REACTIONS

The primary reactions of interest are those resulting in deposition of tungsten
and molybdenum costings by hydrogen reduction of WFg and MoFg, but reactions

' between components of the substrate and WFg or MoFe are also possible. The

standard free energy of reaction of several possible reactions is shown in

Table 2.

The values in Table 2 indicate that displacement reactions between

WF¢ and iron, chromium, and nickel are all thermodynamically favorable, espe-

cially those leading to the formation of FeF; and CrFs.

Similarly, in reac-

tions involving MoF¢ and the substrate, formation of FeF; and CrFi is thermo-
These secondary reactions are believed to be importent
factors controlling adherence of the coatings, as will be described.

dynamically favored.
 

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Table 2. Substrate Reactions

 

 

Temperature OF°

(°c) (kcal)

WFg + 3H, » W + 6HF 600 -138
MoFg + 3H, = Mo + GHF 800 54
WFe + Fe = WF; + FeF, 600 -86
WFg + 2Fe = W + 2FeF, 600 =130
WF¢ + Cr = WF, + CrF, 600 -98
WFg + 2Cr = W + 2CrF, 600 =190
WFg + Ni = WF, + NiF, 600 ~72
MoFg + Fe - MoF, + FeF 800 +11
MoFg + 2Fe = Mo + 2FeF; {00 22
MoFg + Cr -+ MoF, + CrFs 800 4
MoFg + 2Cr - Mo + 2CrF, 800 -82
MoFg + Ni =+ MoF, + NiF; 800 +25

 

PRELIMINARY COATING RESULTS

Smooth tungsten coatings were obtained with a H,/WF, ratio in the range of 5 to
10. In the case of molybdenum coatings, the ratio had to be between 3 and 6.

At lower ratios than 3 the substrates were attacked by MoFg, and at higher
ratios than 6 the coatings were nonuniform in thickness with a rough crystalline
surface.

A visual assessment of the adherence of tungsten-coated specimens indicated
that the coating was not adherent to carbon steel or the stainless steels. In
fact, the coating cracked and separated from these materials during cooling
from the deposition temperature. On the other hand, the coating was adherent
to nickel, the iron-nickel alloys, and the nickel-base alloys. These early
results showed a strong dependence of adherence on the composition of the sub-
strate, and we suspected that the displacement reactions discussed in the
previous section were responsible. A black powder occurred at the interface
between nonadherent tungsten coatings and the substrates. This powder, which
was identified as tungsten by x-ray diffraction, evidently prevented adhesion
of the coating. Although no fluoride compounds were found, they may not have
been present in sufficient amount to be detected.

Two tests were then performed to further evaluate the possibility of displace-
ment reactions. Samples of various substrates were exposed to WFg and to MoFg
at 900°C in the absence of hydrogen. Figure 1 shows the appearance of the
samples. No reaction with WFg was visually detected on the nickel, Hastelloy C,
Inconel 600, Fe—50% Ni, and Fe—35% Ni samples. The other samples had a non-
adherent tungsten coating which varied in luster from bright to gray. Samples
exposed to MoFg reacted more extensively. Again, no reaction could be visually
detected on the nickel, Hastelloy C, and Inconel 600 samples, but all the other
samples had nonadherent molybdenum coatings. These results definitely showed
that WF¢ and MoFg undergo displacement reactions with iron-base alloys, but
react much less, if at all, with nickel and nickel-base alloys.

Subsequently, we applied a 0.00l-in.-thick nickel coating to several stainless
steel specimens by electrodeposition, then bonded the nickel to the stainless
steel by heating to 800°C in hydrogen. Afterwards, a 0.005-in.-thick coating
of tungsten was applied to the specimens by chemical vapor deposition (cvDp).
The beneficial effect of the nickel underlayer on the adherence of the tungsten
coating to type 430 stainless steel is shown in Fig. 2. The tungsten coating
      

 

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”""'A." ni;:k;al ) ‘Hcsnsféulfllo} € Inconel 600 Fe-50 Ni  Fe-35 Ni fype 304 Type 405 Type 430 Carbon steel

Fig. 1. Reaction of WF; and MoFg with Iron- and Nickel-Base Alloys at 900°C.

 
 

Y-9

   
   

8673

Fig. 2. Typicel Tungsten-Coated Specimens. (a) Type 430 stainless steel;
coating cracked and separated. (b) Type 430 stainless steel; nickel-plated
prior to coating. (¢) Inconel 600.

cracked and separated from the specimen without the nickel underlayer, but was
adherent to the specimen having the nickel underlayer. The Inconel 600 speci-
men, a nickel-base alloy, did not require a nickel underlayer for an adherent
tungsten coating.

These preliminary results showed that tungsten coatings were adherent to nickel,
the nickel-base alloys Inconel 600 and Hastelloy C, Fe—35% Ni, and Fe-50% Wi,
and that a thin layer of electroplated nickel on stainless steels prevented or
minimized displacement reactions which result in nonadherent coatings. The
nickel layer, to be effective, had to be bonded to the substrate; bonding was
accomplished by heating to about 800°C for & few minutes in hydrogen.

These results are in asgreement with those of Bryant who related the adherence
of tungsten coatings to the tendency of the substrate to react with WFg¢ to form
fluoride compounds more stable than HF.! Bryant found that tungsten coatings
were adherent to molybdenum, copper, nickel, and cobalt in the temperature

range 325 to 1290°C, but were not adherent to iron and chromium below about
1000°C.

COATING ADHERENCE

In order to qualify as a corrosion-resistant coating, the coatings must be
adherent to the substrates under stress. The adherence of tungsten coatings
to various substrates was evaluated by thermal cycle tests, bend tests, and
tenslle tests. Molybdenum coatings were also subjected to the bend test.

THERMAL CYCLE TESTS

Coated specimens for thermal cycle tests were Hastelloy C and Inconel 600 (10
X 0.875 X 0.073 in.) and nickel-plated type 304 and 430 stainless steels (10
X 0.75 x 0.042 in.). A 0.005-in.-thick coating of tungsten had been deposited
on these specimens at 550°C, 5 torr, and a H/WF¢ ratio of 10. The specimens
were inserted into the hot zone of a 600°C furnace tube, equilibrated for

15 min, then moved into the water-cooled zone (about 25°C) of the tube and
equilibrated for 15 min. Visual and dye-penetrant inspection revealed no
cracks in the coatings after 5 and 10 cycles. After 25 cycles a few cracks
 

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were observed in the coating on one end of the type 304 stainless steel speci-
men, but the coating remained intact. No cracks, blisters, or separation of
the coating were observed on the other specimens. After 50 cycles no other
changes were observed in any of the specimens.

A 4-in.-long section of a 4 3/8-in.-ID Monel vessel that had been coated on the
inner surface with a 0.010-in.-thick layer of tungsten was also thermal cycled
between 25 and 600°C. After 25 cycles the coating was intact with no evidence
of cracks or separation. The section was distorted out of round apparently
due to the difference in thermal expansion between tungsten and Monel. Another
4=in.-long section was cycled 10 times between 25 and 1000°C. Substantially
more distortion occurred in this case and the coatinglcracked in regions of
greatest distortion; however, the coating did not spall. The distortion that
occurred in the cylindrical sections 1s evidence of the adhesion between the
coating and Monel substrate.

BEND TESTS

Coated specimens were bent on the spiral bending jig shown in Fig. 3. The con-
struction of the spira} 3ig has been discussed by Edwards.? The equation of
the spiral is r = ae® , where r is the radius vector, 6 is the angle of rota-
tion, and a is a constant The radius of curvature, p, is related to r by the
expression p = br, where b 1s another constant. The angle & at which a crack
formed in the coating could be determined from the jig, which was graduated in
degrees. The radius of curvature could then be calculated. In this test the
specimens were bent at an ever-decreasing radius of curvature down to a
minimum radius of about 1/2 in. Initially, the bend test was construed as a
screening test. Lacking prior knowledge we expected that the coatings would
be more adherent to some substrates than to others, and that the variation in
adherence could be measured in terms of the radius of curvature at which
separation of the coating occurred. The coatings were almost all so adherent,
however, that very little differentiation between specimens was possible.

Y-98670

 

 

Fig. 3. Spiral Bending Jig.
 

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Specimens for the bend test were 10 in. long by 3/4 in. wide, coated on both
sides. These were bent by hand at room temperature to conform to the curvature
of the bending jig. Then the location of cracks in the coating was observed
with the aid of a dye penetrant. Numerous lateral cracks occurred in the coat-
ings, and the spacing between cracks decreased as the radius of curvature
decreased. Although the coatings cracked during bending, only six coatings
spalled. Spalling occurred only at the minimum radius of curvature, and, in
four of the six cases, the specimens had been plated with Ni-8% P by the elec-
troless process instead of being electroplated with nickel. Figure 4 shows
typical cracks, but no spalling, in coatings on Inconel 600 specimens.

Y-100285

 

 

    

Molybdenu;fi s ffingsfen |
Coating . Coating

Fig. 4. TInconel 600 Bend Specimens Showing
Cracks in the Coatings. ' .
The radius of curvature at which the first crack occurred in the coating is
shown in Table 3. The results are arranged so that substrates of the same
thickness can be compared on the basis of coating type and coating thickness.
Several slight trends 'in the data can be detected: (1) for a constant sub-
strate thickness the radius of curvature at the first crack decreased with
decreasing coating thickness; (2) for a constant coating thickness the radius
of curvature decreased with decreasing substrate thickness; (3) for a given
substrate and coating thickness molybdenum cracked at a smaller radius of

curvature than tungsten; (4) electroplated nickel underlayers provided greater

adherence than electroless nickel; and (5) tungsten coatings were less adherent

- to Hastelloy C than to Inconel 600. V :

TENSILE TESTS

' The bond strength between tungsten coatings-ahd various substrates was further

evaluated by tensile tests. Specimens coated on both sides were cut into
3/4 by 3/4 in. squares, then brazed between steel pull bars so that a tensile

force could be applied perpendicular to the coating-substrate interface. A

tensile test specimen is shown in Fig. 5. Brazing was accomplished by placing
& 0.002-in.-thick sheet of copper between the surfaces to be joined, then
loading the joint to about 500 psi. This assembly was induction heated to the
 

)

Table 3. Results of Bend Tests of Tungsten and
Molybdenum Coated Specimens

 

 

 

Thickness Coating Radius of Curvature
Substrate Material cg:ii;g Thickness &t First Crack, in.
(in.) (in.) Tungsten Molybdenum
Hastelloy C 0.063 0.005 4.1
Inconel 600 0.063 0.005 4.2
Type 304 stainless steel (Ni)  0.063 0.004 4.1%P 4 %P
Type 430 stainless steel (Ni)  0.063 0.004 420 5 3D
Type 304 stainless steel (Ni) 0.063 0.002 0.9¢
Type 430 stainless steel (Ni)  0.063 0.002 < 0.4
Hastelloy C 0.032 0.008 3.2b
Inconel 600 0.032 0.006 3.1,
Hastelloy C 0.032 0.005 2.6 3
Inconel 600 0.032 0.005 2.7, 2.6, 2.4
Type 304 stainless steel (Ni)  0.032 0.003 1.5°
Pype 430 stainless steel (Ni)  0.032 0.003 2.5¢
Inconel 600 0.032 0.002 - 0.7

 

®Nickel underleyer applied by the electroless method; contained 8% P.
bCoa.ting spalled at a radius of curvature of about 1 in.
®Electroplated with nickel.

dNb cracks observed in the coating.

Cogted Y-98672
Specimen

7

   

Fig. 5. Tensile Test Specimen.

brazing temperature in about 3 min, then rapidly cooled. Initially, the cross-
sectional area of the specimens was 0.56 in.?. When the limiting load

(10,000 1b) of the jaws of the tensile machine was applied to an area of

0.56 in.? the stress was 17,800 psi. If the specimens sustained this stress,
the cross-sectional area was usually decreased by machining so that the speci-
mens could be stressed to a higher value. :

The results of tensile tests on tungsten-coated speclmens are shown in

Teble 4. The Hastelloy C specimen was not tested to failure after sustaining
e stress of 17,800 psi. The Inconel 600, Fe-35% Ni, and Fe-50% Ni specimens

each sustained a stress of 33,300 psi, but later fractured at 17,800, 36,800,
and 35,500 psi, respectively, when the cross-sectional area wes reduced.
 

Table 4. Results of Tensile Tests on Tungsten-
Coated Specimens

 

 

Cross-
Maximum
Substrate Sezfii:nal Stress Location of Fracture
(in.2) (psi)

Hastelloy C 0.563 17,800 No fracture
Inconel 600 0.563 17,800 No fracture

(=) 0.300 33,300 No fracture

(v) 0.143 17,800 Braze and coating
Fe-35% Ni 0.563 17,800 No fracture

(2) 0.300 33i300 No fracture

(v) 0.146 36,800 Coating
Fe-50% Ni 0.563 17,800 No fracture

(a) 0.300 33,300 No fracture

(v) 0.156 35,500 Coating
Type 304 stain- 0.563 17,800 No fracture

(l§ss steel (Ni) e .

a 0. 22,400 Braze and coating
Type 430 sta%n—) 0.563 17,800 No fracture

less steel (Ni :

(a) 0.143 . 22,300 Braze and coating
Type 430 sta%n—) 0.563 17,800 No fracture

less steel (Ni

(a) 0.141 17,300 Braze and coating

 

Spirst retest of specimen after decreasing the cross-sectional
ares because of a 10,000 1b load 1limit on the jaws of the
tensile machine.

bS‘econd retest of specimen after another decrease in the cross-
sectional area.

Types 304 and 430 stainless steel specimens finally fractured at about 17,000
end 22,000 psi after first sustaining a stress of 17,800 psi. In the two
iron-nickel specimens the fracture occurred only in the coating, but in the
other specimens the fracture also involved the copper braze metal. In the
latter cases we were not able to determine whether fracture originated in the
coating or in the braze metal. Our results were insufficient to precisely
determine the bond strength, since the strength was probably affected by the
quality of the braze Joint and by cracks in the coating inadvertently caused by
cutting the specimens to slze for the tests. Figure 6 shows the coating sub-
strate interface for a typlcal specimen. The high bond strength obtained in
tensile tests is probably releted to the cleanliness and lack of porosity at
the interface. ,

. CONCLUSIONS

The resulte of this study allow the following conclusions. - Tungsten and molyb-
denum coatings adhere tenaclously to nickel and nickel-base alloys as demon-
strated by thermal cycle, bend, and tension tests. Coatings measuring about
0.005 in. thick would be expected to remain intact during repeated thermal
cycling between 25 and 600°C and when bent to a radius of curvature as small
as 1/2 in. In addition, bond strengths should be about 20,000 psi or higher.
 

 

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Y-100328

Fe-50 Ni W Fe-50Ni W

s 3.0 35 INCHES e ey
I . 10.00 in. 1

ke

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7 INEHE " e e sty
15 |

 

 

e et reeeeeete
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Fig. 6. Tungsten Coating on Fe-50% Ni Alloy.

Tungsten and molybdenum coatings are not adherent to stainless steels because
of secondary substrate reactions; however, equivalent adherence can be obtained
by nickel plating the stalnless steels prior to coating.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the assistance of other memhers of the Qak
Ridge Natlonal Laboratory staff: E. R. Turnbill, deposition experiments;

C. W. Dollins, tensile tests; M. D. Allen, metallography; R. M. Steele, x-ray
diffraction; W. R. Laing, chemical analyses; and C. B. Pollock, J. R. DiStefano,
and W. R. Martin for critical review and helpful discussions.

REFERENCES

1. W. A. Bryant, "The Adherence of Chemically Vapor Deposited Coatings,"
Pp. 409421 in Chemical Vapor Deposition 2nd Intern. Conf., ed. by
J. M. Blocher, Jr., and J. C. Withers, The Electrochemical Society, New
York, 1970. ' .

 

2. J. Rawards, "Spiral Bending Test for Flectrodeposited Coatings," Trans.
- Inst. Met. Pinishing 35, 101-106 (1958). ""'""‘
 

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16.
17.

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20.
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23.
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25.
26.
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30.
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36.
37.
38.
39.

71.
72.
73.
7.

~ 76.

77-78.

79.
80.

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Cleveland, OH 44135

J. J. Lynch, NASA Headquarters, Code RN, 600 Independence Avenue,
‘Washington, DC 20545

I. Machlin, Bureau of Naval Weapons, Department of the Navy,
Washington, DC 20360 '

C. L. Matthews, RDT, AEC, OSR, Oak Ridge National Laboratory

D. J. Maykuth, Battelle Memorial Institute, 505 King Avenue,
Columbus, OH 43201

T. W. McIntosh, RDT, AEC, Washington, DC 20545

J. F. Mondt, Jet Propulsion Laboratory, 4800 Oak Grove Drive,
Pasadena, CA 91103

Peter A. Morris, Director, Division of Reactor Licensing, AEC,
Washington, DC 20545

W.ngtt Division of Isotopes Development, AEC Washington, DC

20545

J. Neff, RDT, AEC, Washington, DC 20545

M. V. Nevitt Argonne National Laboratory, 9700 S Cass Avenue,
Argonne, IL 60439

E. C. Normen, RDT, AEC, Washington, DC 20545

I. Perlmutter, Air Force Materials Laboratory, Wright-Patterson
Air Force Base, OH 45433
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13

J. A. Powers, Space Nuclear Systems Office, AEC, Washington, DC
20545

L. Price, Space Nuclear Systems Office, AEC, Washington, DC 20545
N. E. Promisel, Buresu of Naval Weapons, Department of the Navy,
Washington, DC 20360 ‘
N. T. Saunders, NASA, Lewis Research Center, 21000 Brookpark Road,
Cleveland, OH 44135

F. C. Schwenk, Space Nuclear Systems Office, AEC, Washington, DC
20545

R. J. Schwinghamer, George C. Marshall Space Flight Center,
Huntsville, AL 35812

L. C. Shaheen, Thermo Electron Corporation, 85 First Avenue,
Waltham, MA 02154

M. Shaw, RDT, AEC, Washington, DC 20545

Sidngir Siegel, Atomics International, P.0. Box 309, Canoga Park, CA
913

J. M. Simmons, RDT, AEC, Washington, DC 20545

M. T. Simnad, Gulf General Atomic, P.0. Box 608, San Diego, CA
92112

D. Stoner, Westinghouse, Astronuclear Laboratory, P.0. Box 10864,
Pittsburgh, PA 15236

C. 0. Tarr, Space Nuclear Systems Office, AEC, Washington, DC
20545

Technical Library, Los Alamos Scientific Laboratory,

P.O. Box 1663, Los Alamos, NM 87544

Technical Library, Westinghouse, Atomic Power Division,

P.0. Box 355, Pittsburgh, PA 15230

G. Tummins, Climax Molybdenum Company, Ann Arbor, MI 48103

. R. E. Vallee, Mound Laboratory, P.0O. Box 32, Miamisburg, OH 45342

A. Van Echo, RDT, AEC, Washington, DC 20545

M. J. Whitman, RDT, AEC, Washington, DC 20545

Laboratory and University Division, AEC, Oak Ridge Operations
Division of Technlcal Information Extension