E. M. SHERWOOD
h
LESS COMMON METALS FOR PROCESS EQUIPMENT New research on fabrication techniques, alloy development, and protective coatings promises designers of Process equipment many unexpected benebts
urrent research and development effort in aerospace, cryogenic, and nuclear engineering technology may provide some unexpected benefits for the chemical process industry. As additional experience is gained in the use of special techniques to fabricate large, complex structures from less common metals and their alloys and in their protection and behavior in special environments, designers of chemical process equipment will have at their disposal an increasingly useful body of technical information. However, the sources of relevant information, particularly those presenting property data, are widely scattered in the literature. Because many of these sources contain useful compilations and reviews, it is desirable for an individual or group to study the research data and compile in a concise manner those results of major interest to the chemical process industry. Continuing the trend reported in the 1962 review, many new publications appeared, dealing with less common metals as a group. T o permit easier and more sound fabri-
C
cation of the more refractory nernbers of this group, many unusual processing techniques were investigated. Electron-beam processes were employed for consolidating, purifying, and machining, while lasers were used for welding and cutting. Electrochemical and spark processes were used for machining. Ultrasonic energy aided in consolidation of materials during hot pressing. Deep drawing, stretchforming, extrusion, spinning, highenergy-rate forming, and diffusion bonding under pressure were thoroughly investigated. Chemical vapor deposition received considerable attention as a production tool. Means of rolling very thin refractory metal foils were developed. Much attention was given to preparation of the less common metals in a state of high purity, using both chemical and physical means of purification. New alloys with improved superconductor properties were devised. Extensive evaluation of irradiation damage and recovery was carried out, and a better insight was obtained into the effect of
structural defects on an atomistic level in behavior during irradiation. There can be little doubt that less common metals merit further consideration by the chemical industry as materials of construction for special applications, particularly because so much now is known about them. Availability, processing, properties, and applications of the less common metals were reviewed by many authors, but only a few of these reviews can even be listed (27, 57,90). Several symposia gave prominence to preparation and e\ aluation of the less corn-mon metals in a state of high purity (4, 7, 20,7 04). Consolidation (96, 707) and working (29, 46, 72, 87, 88) were widely studied, but greatest emphasis was placed on the use of processes involving vacuum and electron-beam technology (72, 47, 59, 83, 700). Joining the less common metals can be successfully accomplished by fusion welding, solid-state diffusion bonding, and brazing (74, 75). Electrochemical machining is particularly attractive for shaping com-
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More knowledge of fundamental behavior is leading to new applications plex parts from the refractory less common metals (37). Much more now is known about the how’s and why’s of irradiation damage in bodycentered cubic metals, such as Mo, Nb, and W (54). The benefits of alloying as a means of strengthening the ref1 actory metals are well known and such aspects as strengthening mechanism are being evaluated (5). Likewise, high temperature characteristics of the so-called “hard” compounds of less common metals (beryllides, borides. carbides, nitrides, and silicides) are attractive for many applications (84). Now that more is known about the four simultaneous phenomena which occur when a refractory metal oxidizes-i.e., solution of oxygen in the metal, nucleation and growth of a suboxide phase at the metal surface, and two-phase boundary processes giving rise to two different modifications of the same oxidprotective coatings can be devised which are more effectiL e (77). Periodic reviews of this coating field are now issued (36). Use of the less common metals themselves as coatings for various applications increased during the year just passed. In forming both coatings and freestanding shapes, chemical vapor deposition, a “rediscovered” production tool, has proved useful (8, 74). Helpful reviews of the less common metals as materials of construction for chemical plant service (44), in aerospace applications (37),and as superconducting alloys (42). lent breadth of coveraqe to the field of applications these materials now enjoy. Beryllium
Problems and the properties associated with beryllium and its alloys were reviewed (32, 47). Improved processes for extracting (69) and
E. M . Sherwood is Assistant Chief, Chemical Vapor Detosition Division, Battelle Memorial Institute in Columbus, Ohio. He has authored I&EC’s Less Common -Metals Review since 7955. AUTHOR
60
refining (703) beryllium were developed. Consolidation of beryllium by powder-metallurgy techniques received considerable attention (63, 95). New developments in welding (52) led to structures with improved characteristics. Exposure to nuclear environments (53)and the influences of impurities and vacuum coatings (92) on the corrosion of beryllium were evaluated. Intermetallic compounds of beryllium with Mo, Nb, Ta, and W possess excellent mechanical properties at ultrahigh temperatures (22). Very fine beryllium wire (0.005 inch in diameter) shows increased tensile and yield strength and an improved strength-to-weight ratio over conventional beryllium wire (34).
deposition was employed to prepare very fine molybdenum (and tungsten) powders in the 0.01- to 0.1-micron size range which may lead to new uses of these metals for structural and other applications (58). In addition, high-purity molybdenum in consolidated form was prepared by chemical vapor deposition ( 6 ) . Although difficult to machine, molybdenum can be handled both by mechanical and electrochemical methods (93). Molybdenum, as an alloying agent in stainless steels, nickel-, tungsten-, and zirconiumbase alloys, enhances corrosion resistance (24,33). A number of new applications for molybdenum as a structural material were disclosed
(30).
Chromium Niobium
\Vorld resources, production, marketing, mining, beneficiation methods, and applications of chromium were reviewed broadly (98). A review of properties and some thoughts regarding the future prospects for chromium and its alloys in high temperature service was presented (89). Chromium is one of the metals which, in high-purity form, has very interesting properties. Characteristics of high-purity iodide chromium were described (7, 65)and development of chromium composite alloys, containing a finely dispersed oxide phase, for application at 2000’ to 3000’ F. was announced (65). Hafnium
Interest in hafnium appears not great at present. One excellent review appeared (97). Hafnium containing up to 307, Zr, has good corrosion resistance in contact with high temperature water (350’ C.) (39). Further, prolonged exposure of hafnium in a steam-water medium at 350’ to 400’ C . does not lead to noticeable impairment of mechanical properties. Molybdenum
Several comprehensive reviews covering molybdenum and its alloys appeared (77, 48). Chemical vapor
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
Reviews on niobium were slanted toward nuclear engineering (55)and aerospace (70)applications. The halide compounds of niobium are becoming more important as source materials for the metal. Niobium (and tantalum) was prepared by thr Ka or Mg reduction of the pentachloride using the Kroll process (78), and by the thermal decomposition of the iodide by the Van Arkel-de Boer, hot-wire process. Both techniques are capable of yielding a high-purity metal product. Welding studies on niobium and its commercial and experimental alloys (35, 76) provided new information on the effect of alloying agents and welding atmospheres on properties such as bend ductility, hardness, ductile-to-brittle transition temperature, yield strength, and tensile strength. Mechanism and effects of the reaction of niobium with water vapor and oxygen at 200’ to 1200’ C. (73) and with oxygen and hydrogen (49) were investigated. The socalled breakaway oxidation which occurs between 400’ and 500’ C. in oxygen and between 750’ and 950’ C. in water vapor is caused by nucleation and growth of Nbz05 (73). Increasing the oxygen and hydrogen content of niobium produces in-
creased strength and raises the ductile-to-brittle transition temperaure (49). A study was made of the effect of second-phase strengthening as obtained by solution treatment and ging of Nb alloys (78). Zircolium and hafnium additions to niobium improve susceptibility to age hardening. Zirconium also promotes dispersion strengthening of niobium by reacting with C and 0 impurities present. Review of Nb alloy development studies disclosed new data on Nb alloys with Zr-C, Hf, Mn, and W (77). The most important new application for Nb and its alloys lies in the field of superconductivity. Numerous studies in this area were reported (94,702). Rhenium
Reviews on the chemistry (60) and general properties (82) of rhenium were published. Although rhenium is not plentiful, it has come into use in such special applications as electrical contacts, thermocouple alloys, electronic devices, brazing alloys, as an electrodeposited coating, and as a catalyst (79). A study was made of the influence of oxygen on the properties of zone-refined rhenium (85). Tantalum
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Chemical, physical, mechanical, and electrical properties of tantalum were summarized and its applicaions were reviewed (76). Very thin oils of tantalum (and zirconium) are needed in new nuclear engineering applications. Special equipment, located in dust-free areas, is required to produce such foil (62, 88). Owing to its excellent hightemperature mechanical properties and favorable fabrication characteristics, tantalum continues to receive attention as a material of construction for special structures. However, its relatively strong affinity for oxygen makes the use of both alloying agents and protective coatings desirable. By learning more about tantalum's oxidation mechanism, 'better protective means probably can be devised. Hence, numerous studies of oxidation have been made (26, 56). The results of corrosion
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testing of tantalum in such media as acids, molten metals, molten salts, and vapors and gases are of particular interest to chemical process engineers (28). T h e oxidation resistance of thin tantalum films prepared by sputtering in vacuum is considerably greater than that of bulk tantalum tested under the same conditions (77). Tungsten
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Favorable behavior in extreme aerospace environments and the use of improved techniques of preparation and fabrication have created renewed interest in tungsten (9, 61). Improved physical and mechanical properties are achieved in diffusionbonded tungsten structures ( 3 ) . Temperatures no higher than 2350’ F. (a temperature well below the recrystallization temperature of tungsten) are requircd. Cutting and welding of tungsten by both electrobeam (68) and laser (99) processes can be carried out successfully and may provide new production tools for many industries. Useful cornpilations of data on the tensile properties of tungsten were published (43, 80). As in the case of tantalum, but even to a greater extent for tungsten, reaction with oxygen is a major stumbling block in many high temperature applications. hTew information about the kinetics and mechanism of this reaction was developed (57,70), and protective coatings against oxidation were described (38). Coatings and bulk deposits of tungsten were prepared by chemical vapor deposition using hydrogen reduction of tungsten hexafluoride (66) and thermal decomposition of tungsten bromides (79). I n both cases, the deposition takes place on a heated surface at a temperature well below the melting point of tungsten, so that relatively low melting substrates can be used. Satisfactory coatings of tungsten also can be applied by plasma-arc spraying (64). Zirconium
The current status of zirconium technology was reviewed (45) and an analysis was made of its potential
Circle No. 52 on Readers’ Service Card
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I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
future applications in the chemical and nuclear industries (67). Techniques of producing Zr and Zircaloy tubing by extrusion and drawing were described (97). Zirconium and its alloys are most often used in applications where oxidation and corrosion resistance as well as mechanical properties are important, with emphasis on nuclear environments (2, 75, 25, 27, 40, 87). Hence, the effect of irradiation on these properties must be known (50). I n some cases, additional protection against oxidation must be provided (23). As a protective coating, zirconium has found use on molybdenum and stainless steel substrates (73). Such coatings are best applied by chemical vapor-deposition processes. I n chemical-plant service, zirconium compares well and even surpasses many stainless steels in important chemical and mechanical properties (86). BIBLIOGRAPHY (1) .4banin, D. D., Statsenko, V. E., Yemel’yanov, V. S., Yevstyukhin, A. I., in “Metallurgy and Metallography of Pure Metals,” p. 10, Gordon and Breach, New York, 1962. (2) Akram, K. H., Smeltzer, W. W., Can. Metals Quart. 1, 41 (July-September 1962). (3) Albom, M. J., Welding J . (iV.Y.)41, 491s (November 1962). (4) American Society for Metals, “UltraHigh Purity Metals,” .4SM, Metals Park, Ohio, 1962. (5) Armstrong, R. W., Bechtold, J. H., Begley, R. T., in “Refractory Metals and Alloys 11” (M. Semchyshen and I. Perlmutter, eds.) , Metallurgical Society Conferences, Vol. 17, p. 159, Interscience, New York: 1963. (6) Badiali, M. A., Kirschenbaum, 11. I\’., Bakish, R., Trans. M e t . Sac. AZME 227, 32 (February 1963). (7) Bakish, R., J . Metals 14, 229 (March 1962). (8) Bakish, R., Gellar, C. A., Marinow, I., Zbid.,14, 770 (October 1962). (9) Barth, V. D., Defense hletals Inform. Center Rev. Recent Developments (Aug. 24 and Nov. 23, 1962; Jan. 15, 1963). (10) Bartlett, E. S.; Schmidt, F. F., Defense Metals Inform. Center Rev. Recent Developments (July 10, 1962). (11) Basseches, H., J . Electrochem. Soc. 109, 475 (June 1962). (12) Beckett, F. J., Burtenshaw. P., Metallurgia 65, 107 (March 1962). (13) Blackburn, P. E., J . Electrochem. Soc. 109,1142 (December 1962). (14) Blocher, J. M., Jr.: Battelle Tech. Reo. 12, 2 (March 1963). (13) Boulton, J., in “Corrosion of Reactor Materials,” Vol. 2, p. 133. International Atomic Energy Agency, Vienna, 1962.
(16) Bourzes, M., Metallurgze (Paris) 94, 1173 (December 1962). (17) Braun, H., Metall 16, 646 (July 1962). (18) Campbell, T. T., Block, F. E., Robidart, G. B., Schaller, J. L., U. S. Bur. Mines, Rept. Invest. 6080, 1962. (19) Caves, R. M., Trans. Met. SOC.A l M E 224, 267 (April 1962). (20) Chang, W. H., Timmons, G. A., J . Metals 14, 187 (March 1962). (21) Chelius, J., Chem. Eng. 69, 178 (Dec. 10, 1962). (22) Chem. Rundschau 15, 731 (Dec. 1, 1962). (23) Corrosion Prevent. & Control 9, 44 (May 1962). (24) Ibid., 29 (October 1962). (25) Cotton, J. B., Gallant, P. E., in “First International Congress on Corrosion,” p. 458, Butterworths, London, 1962. (26) Cowgill, M. G., Stringer, J., J . Inst. Metals 91,220 (February 1963). (27) Cox, B., J . Nucl. Energy Pt. B 2, 166 (February 1962). (28) Cox, F. G., Corrosion Prevent. 3 Control 10, 56 (February 1963). (29) Crimmins, P. P., Heimlich, C. W., Metal Progr. 82, 66 (December 1962). (30) Czarnecki, E. G., Stacy, J. T., Zimmerman, D. K., in “Refractory Metals and Alloys 11” (M. Semchyshen and I. Perlmutter, eds.), Metallurgical Society Conferences, Vol. 17, p. 395, Interscience, New York, 1963. (31) Faust, C. L., Battelle Tech. Rev. 12, 7 (January 1963). (32) Finniston, H. M., Research (London) 15, 109 (March 1962). (33) Fox, G. F. P., Corrosion Prevent. @ Control 9, 43 (December 1962). (34) Fulop, R. J., Mater. Design Eng. 5 5 , 10 (March 1962). (35) Gerken, 3. M., Faulkner, J . M., Welding J . ( N . Y.) 42, 84s (February 1963). (36) Gibeaut, W. A., English, J. J., Defense Metals Inform. Center Rev. Recent Developments (Aug. 3 and Nov. 2, 1962; Jan. 25, 1963). (37) Gibeaut, W. A,, Maykuth, D. J., Defense Metals Inform. Center Rept. 175, Sept. 24, 1962. (38) Geotzel, C. G., Landler, P., in “Powder Metallurgy in the Nuclear Age,” p. 759, Metallwerk Plansee AG., Reute/ Tyrol, 1962. (39) Grebennikov, R. V., Shamoshov, F. P.: in “Corrosion of Reactor Materials,” Vol. 2, p. 149, International Atomic Energy Agency, Vienna, 1962. (40) Griggs, B., Maffei, H. P.: Shannon, T I . W., J . Electrochem. Sot. 109, 665 (August 1962). (41) Gruber, H., Metal Treat. Dro$ Forging 29, 141 (April 1962); 29, 191 (May 1962). (42) Hake, R. R., Berlincourt, T. G., Leslie, D. H., in “Superconductors” (M. Tannenbaum and W. V. Wright eds.), p. 53, Interscience, New York, 1962. (43) Harmsworth, C. L., Parechanian, H. S., Leggett, H., S.A.E. Preprint 520A, 1962. (44) Hepner, I. L., Chem. Proce.rs Eng. 43, 180 (April 1962). (45) Herenguel, J., “Zirconium and Its Alloys,” Special Metallurgy, Vol. 3,
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VOL. 5 5
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Presses Cniversitaires de France, Paris, 1962. (46) Hockett, J. E., Appl. Mech. Reu. 15, 157 (March 1962). (47) Hodge, W., Defense Metals Inform. Center Rept. 168, May 18, 1962. (48) Houck, J. A., Defense Metals Inform. Center Rev. Recent Developments (Apr. 6 and July 6, 1962; Jan. 4, 1963). (49) Imgram, A. G., Bartlett, E. S., Ogden, H . R., Trans. Met. SOC.AIME 227, 131 (February 1963). (50) International Atomic Energy Agency, “Radiation Damage in Solids,” Vol. 2, International Publications, N e w York, 1962. (51) Jaffee, R . I., Maykuth, D. J., Mater. Res. Std. 2, 412 (May 1962). (52) Jahnle, H. A., Welding J . (A’. Y.) 41, 331 (April 1962). (53) Jepson,-W. B., Research (London) 15, 288 (July 1962). (54) Johnson, A. A., Milasin, K.,Zein, F. N., in “Radiation Damage in Solids,” Vol. 1, p. 259, International Publications, New York, 1962. (55) Joly, F., Energie Nucl. 4, 189 (May 6, 1962). (56) Kofstad, P., J. Inst. Metals 91 (February 1963). (57) Lally, F. J., Hiltz, R. H . ; J . Metals 14,424 (June 1962). (58) Lamprey, H., Ripley, R . L., J . Electrochem. Sac. 109, 713 (August 1962). (59) Lawley, L., in “Introduction to Electron Beam Technology,” p. 184, Wiley, New York, 1962. (60) Lebedev, K . B., “Chemistry of Rhenium” (English transl.), Butterworths, London, 1962. (61) Li, K. C., J . Metals 14, 413 (June 1962). (62) Light Metals 25, 282 (October 1962). (63) Martin, A. J., Ellis, G. C., in “Powder Metallurgy in the Nuclear .Age,” p. 645, Metallwerk Plansee AG., Reutte/Tyrol, 1962. (64) Mash, D. R., in “Materials Science and Technology for Advanced Applications,” p. 656, Prentice-Hall, Englewood Cliffs, N. J.; 1962. (65) Masterson, J. F., S.A.E. J . 70, 31 (June 1962). (66) Miller, A., Barnett, G. D., J . Electrochem. SOC.109, 973 (October 1962). (67) Miller, G. L., Metal. Ind. (London) 101, 301 (Nov. 15, 1962). (68) Monroe, R. E., Evans, R. M., Defense Metals Inform. Center Memo. 152,May 21, 1962. (69) Morana, S. J., Simons, G. F., J . Metals 14, 571 (August 1962). (70) Ong, J. N., Jr., J . Electrochem. Sac. 109, 284 (A4pril1962). (71) Ong, J. N., Jr., Fassell, W. M., Jr., Corrosion 18, 382t (October 1962). (72) Ostermann, F., Metall 16, 656 (July 1962). (73) Owen, L. W., Fairman, L., Trans. Inst. Metal Finishing 39, 98 (1962). (74) Pattee, H. E., Evans, K. M., Defense Metals Inform. Center Memo 153, June 11, 1962. (75) Platte, W. Tu‘., in “Refractory Metals and Alloys 11” (M. Semchyshen and I . Perlmutter, eds.), Metallurgical Society Conferences, Vol. 17, p. 307, Interscience, New York, 1963. (76) Platte, W. N., Welding J . 42, 69s (February 1963).
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INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
(77) Pollock, W. I., Metals Eng. Quart. 2, 58 (November 1962). (78) Pollock, TI;. I., in “Materials Science and Technology for Advanced Applications,” p. 576,-Prentice-Hall, Engiewood Cliffs, N. J., 1962. (79) Port, J. ‘H., Wire Wire Prod. 38, 370 (March 1963). (80) Ratliff, J. L., Ogden, H. R . , Defense Metals Inform. Center Memo. 157, Sept. 11, 1962. (81) Rostoker, W.: in “Refractory Metals and Alloys 11‘’ (M. Semchyshen and I. Perlmutter, eds.), Metallurgical Society Conferences, Vol. 17, p. 379, Interscience, New York, 1963. (82) Sagoschen, J., Metall 16, 1193 (December 1962). (83) Samarin, A. M., Vide 17,53 (JanuaryFebruary 1962). (84) Samsonov, G. V., Umanskii, Ya. S., I\iASA Tech. Transl. F-102,June 1962. (85) Savitskii, E. M., Chuprikov, G. E., Izu. Akad. Nauk SSSR, Met. i To#liuo (4), 137 (1962). (86) Schemel, J. H., Mater. Protection 1, 20 (July 1962). (87) Sense, K. A,, J . Electrochem. SOC.109, 377 (May 1962). ( 8 8 ) Shet k e t a l I&’. 39, 31 6 (May 1962). (89) Sims, C. T., J . Metals 15, 127 (February 1963). (90) Smallman-Tew, K.? Nat. Res. Council Can. Rept. LR-358,November 1962. (91) Sperner, H., Metall 16, 679 (July 1962). (92) Steele, J. R., Mater. Protection 1, 59 (July 1962). (93) Stewart, I. J.; Tool M f g . Engr. 50, 77 (February 1963). (94) “Superconductors” (M. Tannenbaum and W. V. Wright, eds.), Interscience, New York, 1962. (95) Syre, R., Logerot, J. M., in “Powder Metallurgy in the Nuclear Age,” p. 677, Metallwerke Plansee AG., Reutte/Tyrol, 1962. (96) Tarpley, W.B., Kartluke, H., USAEC Rept. NYO-10007, December 1961. (97) Thevenet, J., Buffet, J., Rev. Met. (Paris) 59, 553 (June 1962). (98) U. S. Department of Commerce, “Materials Survey-Chromium,” U. S. Government Printing Office, lVashing-ton, D. C., 1962. (99) Western Machinery and Steel W o r l d 53, 68 (May 1962). (100) TVhite, S. S., Bakish, R., in “Introduction to Electron Beam Technology,” p. 212, Wiley, New York, 1962. (101) Wong, J. S., Christopher, S. S., [Vorcester, S. .4.,Jr., in “Refractory ,Metals and Alloys 11” (M. Semchyshen and I. Perlmutter, eds.), Metallurgical Society Conferences, Vol. 17, p. 351, Interscience, New York, 1963. (102) SVong, J., in “Superconductors” (M. Tannenbaum and W. V. Llirigh_t, eds.), p. 8 3 : Interscience, New York, 1962. (103) Wong. M. M., Campbell, R. E., Baker, D. J., Jr., U. S. Bur. Mines, Rept. Invest. 5959, 1962. (104) Yemel’yanov, V. S., Yevstyukhin A. K., Leont’yev, G. A., in “Metallurgy and Metallography of Pure Metals” (V. S. Yemel‘yanov and A. I. Yevstyukhin, eds.), p. 23, Gordon and Breach, New York. 1962.
