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Bureau of Mines / Minerals yearbook: Metals, minerals, and fuels 1972
Year 1972, Volume 1 (1972)

Stevens, Richard F., Jr.
Tungsten,   pp. 1239-1259 ff. PDF (2.4 MB)

Page 1259

Materials Science and Technology Division of the American Nuclear Society
at the University of Utah in Salt Lake City.a7 Topics covered included fundamentals
and techniques of (ND processes, composites, coatings, fibers, and powders;
and application. 
 Continuing studies on vapor-deposited tungsten by National Aeronautics and
Space Adminisration (NASA) metallurgists at the Lewis Research Center indicated
that mechanical properties could be improved by the selective incorporation
of various nonmetallic impurties.SS 
 Additional studies of the mechanical behavior of CVD tungsten by University
of Utah research metallurgists indicated a lower strength than that of standard
powder metallurgy tungsten.39 A way to fabricate complicated tungsten shapes
was developed in which gaseous tungsten hexafluoride and hydrogen react at
high temperatures to deposit pure tungsten on a copper pipe or mandrel.40
When the copper is etched out, a pure tungsten pipe remains. 
 To eliminate the minute pits and flaws that lower the strength and -increase
the rate of rejects in cemented tungsten carbide products, Kennametal developed
a process for producing exceptionally highquality cemented tungsten carbide
forms by simultaneous application of isostatic pressure of up to 20,000 pounds
per square inch, and elevated temperature up to 
2,750° F.4' 
 In addition to using hot isostatic processing for bonding and pressing tungsten
metal powder in variety of applications, several companies have reported
using this process to manufacture tungsten carbides and tool steels.42 
 Consolidated tungsten metal was produced in good yields on a small scale
by aluminothermic reduction of tungstic oxide with small amounts of calcium
and sulfur to initiate the reaction at 450° C.43 The aluminum in the
consolidated tungsten, which initially contained 1,400 parts per million,
0.14%, was subsequently reduced to 30 parts per million by nonconsumable
arc melting. - 
 Submicroscopic gas bubbles trapped in doped tungsten filaments impart greater
high-temperature strength to the metal by solid solution or dispersed second
phase alloying.44 
 Tungsten alloys having excellent tensile strength and stress-rupture properties
at 1,650° C and 1,920° C were prepared from sintered powder blends
of tungsten and tungsten zirconium or zirconium nitride by high-impact (Dynapak)
extrusion.4~ The strengthening was attributed to solid solution strengthening
by zirconium and by submicron particles of zirconium dioxide. 
 A study of the development of submicroscopic porosity in several grades
of doped tungsten wire was conducted in the temperature range between 3,000°
and 3,350° C.46 The extremely small submicroscopic pores inhibit - recrystallization
and permit development of the interlocking grain structure necessary for
sag-resistant filaments. 
 A prototype device was developed for semiautomatic gas tungsten arc welding
of small diameter tubing.47 Because the torch nozzle is always centered over
the weld joint where the arc is started, the arc length remains constant
and arc initiation is easier since the tungsten is preset for the weld. 
 37 Glaski, F. A. (ed.). Proceedings of the Third International Conference
on Chemical Vapor Deposition. Am. Nuclear Society (Hinsdale, Ill.), 1972,
787 pp. 
 38 National Aeronautics and Space Administration. Nonmetallic Impurities
Improve Mechanical Properties of Vapor-Deposited Tungsten. NASA Technol.
Brief B72—l0454, August 1972, 1 pp. 
39 Chun, J. S., H. S. Shim, and J. G. Byrne. 
Mechanical Behavior of Chemical Vapor Deposited 
Tungsten. Met. Trans., v. 3, No. 12, December 
1972, pp. 3093—3096. 
 40 Chemical and Engineering News. Tungsten Shapes. V. 50, No. 27, July 3,
1972, p. 13. 
 41 Kennametal Inc. Anssual Report 1972, 19 pp. 
 42 Boyer, C. B. Hot Isostatic Processing. Chem. 
Eng. Progress, v. 68, No. 5, May 1972, pp. 
78—80. The complete 28-page manuscript may be 
obtained from AIChE Pub. Dept. 345 E. 47th 
St., New York. 
 43 Belitskus, David. Aluminothermic Properties of Metals and Alloys. J.
Metals, v. 24, No. 1, January 1972, p. 34. 
 44 Dawson, Chester. Effect of a Temperature 
Gradient on Bubble Growth in Tungsten. Met. 
Trans., v. 3, No. 12, December 1972, pp. 3103— 3107. 
 Sell, Heinz G. and George W. King. Bubble Strengthening a New Materials
Concept. Res.f Development, v. 23, No. 7, July 1972, pp. 18—21. 
 45 Blickensderfer, R., M. I. Copeland, and W. L. O'Brien. Strengthening
of Tungsten by Powder Metallurgical Internal Oxidation. Internat. J. of Powder
Met., v. 8, No. 3, July 1972, pp. 
 46 Brett, J., and S. Friedman. High-Temperature Porosity in Tungsten. Met.
Trans., v. 3, No. 4, April 1972, pp. 769—778. 
 47 National Aeronautics and Space Administration and Small Business Administration.
Spinarc Gas Tungsten Arc Torch Holder. Welding Technol., NASA SP—59l8(02),
1973 p. 32. (Available from the National Technical Information Servsce, Springfield,

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