and Its Alloys
___
ROBERT J. KERERVIS T i n Research I n s t i t u t e , Inc., Columbus 1 , Ohio
As far as supplies are concerned, there is plenty of tin.
shown that the corrosion and tarnish resistance of this alloy coating is at least comparable t o traditional chromium-on-nickel electrocoatings ( 7 2 ) . Any process that involves the use of nickel has special difficulties a t this time of nickel shortages. Since only one third of this coating alloy is nickel, this coating method is, in fact, a method of saving nickel. Accordingly, it has beensufficiently promising to warrant several large commercial installations (55, 91). Figure 1 is an illustration of one of these installations. Tin-Zinc Alloy Plating. Great strides have been made in tin-zinc (50 to 80% tin) electroplating ECAUSE of critical shortages, brief summaries on the supply since it first was adopted commercially in 1947 (88, 101j , Figure 2 picture were included in last year’s Materials of Construcis an illustration of one of the many commercial installations which tion Review. This year there is considerable improvement with is in continuous operation. It was not until this year, however, regard to metals, at least. The United States Government rethat sufficient time had elapsed since the introduction of this procstrictions on a number of metals were removed. Tin is still reess to evaluate fully the corrosion behavior of tin-zinc electrostricted. Just recently, the Government has ceased being the coatings in urban, suburban, and marine atmospheres. Published sole importer of tin and further decontrol may be on the way. For results on weathering tests show that tin-zinc coatings have adthe past 4 years, production has outdistanced consumption convantages over pure zinc coatings when prolonged humidity is ensiderably. The world picture on tin a t the end of 1951 was as folcountered. Also, it is excellent for applications requiring coatings lows: which are easily solderable with weak noncorrosive fluxes (15). A particularly interesting use of the tin-zinc alloy is the plating of Production (1951), Consumption (1951), Stocks (End of Long Tons Long Tons 1951), Long Tons nuts and bolts and other components that are used in contact with 166,000 136,000 251,500 aluminum. Comparative test performances of tin-zinc coatings (goyo tin) with zinc-electroplated, cadmium-electroplated, sharadized, parkerized, or black oxide finish coatings in salt spray, These are International Tin Study Group figures. The figure on humid sulfur dioxide, marine, or industrial atmospheres show stocks includes an estimated 150,000tons transferred to the U. S. tin-zinc coatings t o be the best protection that can be provided strategic stockpile. Reserves of tin ore are adequate. Tin has for components in contact with aluminum structures (90). been considered scarce because the major fields in the Far East Lead-Tin Alloy Plating. For a number of years, lead-tin elecare considered vulnerable. troplated alloys have been used for engineering applications such This year there are new developments in most of the fields in as break-in surfaces for machine parts, running surfaces for bearwhich tin is used. Probably the most interesting from the layings, and for corrosion resistman’s point of view is the use ance. Improved commercial of tin fluoride toprevent tooth plating methods have been cavities (66), tin fluoride bethe subject of recent reviews ing superior to sodium fluo(15, 66, 87). A new use for ride for this purpose. From this coating is to facilitate the viewpoint of industrial soldering of brass, copper, and and engineering chemistry, steel ( 2 5 ) . Corrosion behavior there are significant developof lead-tin coatings has been ments in many of the end studied by the British Gas products using tin. These Reserve Board (44j. will be discussed in the apCop’per-Tin Alloy Plating. proximate order of their imKen. developments in the mediate importance in these particular fields. electroplating of copper-tin alloys include red bronze platTIN ALLOY ELECTROing as a stopoff for selective PLATING case hardening ( 2 8 ) and the Tin-Nickel Alloy Plating. electrodeposition of copperCorrosion resistance studies tin alloysfromfluoboratesoluon the extremely tarnish-retions ( 5 ) . sistant tin-nickel coating (65 Control of Tin Alloy Elecparts tin, 35 parts nickel) Figure 1. Semiautomatic Tin-Nickel Plating Bath Used troplating Baths. The control for Plating Automotive Trim announced last year have
Production has exceeded consumption considerably for the past 4 years. Two outstanding new materials have been announced. Neither has been fully investigated, but initial developments indicate that new improved aluminum tin-hearing alloys may offer the desirable properties of babbitts with many times their fatigue resistance and that new precipitation hardening tin bronzes may allow a marked reduction in expensive beryllium without sacrificing strengths. Another new and important use for an established material is the use of tin bronzes for condenser tubes to replace cupronickel and so help relieve the critical nickel shortage. Tin bronze is in every respect the equivalent of cupronickel for this application and i n some cases is superior. Other outstanding developments include a method of bright electrotinning, a n effective method of soft soldering ceramics to metals, and a new immersion tin-plating method that can also be used to boost deposition in inaccessible areas during electrotinning.
2360
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INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1952
2361
of plating conditions is very critical in most alloy plating processes. The Hull cell is a particularly useful control tool, and its use in tin alloy electroplating has been studied (16). ELECTROTINNING AND IMMERSION TINNING PRACTICE
“,
Present methods of electrotinning do not yield a bright tin coating. The electro-tin coating must be melted after deposition t o achieve brightness. A new method of producing bright as-deposited electro-tin coatings has been patented ( 17 ) . It involves superimposing alternate current on direct current in a stannate bath. The method permits higher current densities than are feasible with direct current alone with higher current efficiencies. Another new and interesting development in electrotinning is the use of aluminum contacts during electro-tin plating to boost deposition on inaccessible areas, such as the inside of small tubes, etc., thus dispensing with the necessity of using auxil,iary, anodes (99). This development came about as a result of a discovery of a related development, viz., the use of aluminum for contact tinning using the usual stannate plating solution but without current. Exceptionally dense and adherent coatings on most metals, including cast iron, many alloy steels, brass, and copper, may be deposited by: this simple immersion method. Deposition does not cease when the base metal is covered, and fairly thick deposits can be built u p in a reasonable time. A rather special use for tin coatings is as a drawing lubricant in the so-called liquor finishing of steel wire. This tin coating is very thin and is usually applied over copper, both coatings being applied by simple immersion processes. A more rapid immersion liquor finish process has been patented (48). The growth of “whiskers” on many electroplated metal.coatings is a puzzling phenomenon which has frequently been the cause of high-frequency losses a t low currents. The phenomenon of whisker growth on electrotinned coatings has been studied (7, 20).
COURTESY BRITISH SMALL ARMS 00.. LTD.
Figure 2.
Semiautomatic Tin-Zinc Plating Bath Used for Finishing Motorcycle Parts
-
1900-aallon caoacitv *~ Chief outlet for tin-zinc as a solderable plate in the electronic and electrical industrics
ELECTRO-TIN PLATE MANUFACTURE
Probably the most newsworthy item in commercial electro-tin plate manufacture is the production of differentially coated electro-tin plate, i.e., tin plate having one side heavier than the other, the heavy side being destined for the inside of fruit, vegetable, and meat cans (60, 67). It is expected that this differentially coated tin plate will replace most of the relatively heavily coated hot-dip tin plate that is now used for these products. The lighter side of the differentially coated sheet is identified by a rougher or etched surface on the steel base. New patents in the electro-tin plate field include improvements in commercial strip electroplating, such as the use of adjustable auxiliary anodes in a stannate electroplating line to secure more uniform coatings (39) and the use of improved acid electrolytes to broaden the effective current density range, make precise control unnecessary, and make possible heavy coatings of good quality (1). TIN-PLATE PRODUCTION
Figure 3 is an illustration of a continuous annealing furnace for tin-plate steels that has been installed recently a t the Gary tin mill of U. S. Steel Co. This improved unit is designed to a protective atmosphere. tee1 surface which is very corrosion (83). It is the being canstructed. e manufacture i s the use of nitrogen additions in the l a d e t o secure additional hardness in tin plate (98). /
RROSION RESISTANCE OF TIN-PLATE CONTAINERS
of the factors which will delay the adoption of differen-
tially coated electro-tin plate is the erratic corrosion behavior of
present day electro-tin plate. The various factors affecting the shelf life of canned foods have been studied rather intensively (49-61). Annealing atmospheres used in the manufacture of the steel sheet and their consequent effect on the surface of the steel base have been found to be one of the factors responsible for the erratic corrosion behavior of electro-tin plate (59, 96). A rapid control test to measure the extent of this effect with various annealing atmospheres has been evolved (59). The effect of oxide films on tin plate and methods of retarding films by phosphate-chromate treatments have also been studied ($8,S2, 33). Results of long industrial experience and study have shown that the protective film can best be applied by first cleaning cathodically and then immediately oxidizing anodically in the same phosphate-chromate solution (28). The anodic treatment provides desirable effects, such as excellent resistance to further oxidation during storage, excellent resistance t o further oxidation and discoloration during baking, excellent resistance to sulfide staining from foods, and improved abrasion resistance of the protective film. Unfortunately, these good effects are acquired a t the expense of lacquer adherence properties. Since the adherence of lacquered can linings is most important, the best compromise appears to be to reduce the current density for the anodic portion of the treatment so that good resistance t o both storage and baking discoloration may be obtained with only a slight sacrifice of the degree of lacquer adherence. The general subject of protective organic linings for food cans has received attention this year (41, 78). CORROSION RESISTANCE OF OTHER TIN COATING
A recent discovery which has fairly important practical aspects is that the corrosion of tin in strong alkaline solutions is accelerated by contact with iron even in the absence of oxygen (18)
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Thus, in the cleaning of tinned ware in alkaline solutions, contact with a bare steel tank should be avoided. Another practical finding is that tin coatings on copper do not always furnish anodic protection to copper. Corrosion products that are more noble than the copper may form on the tin coatings, thus leading to pitting corrosion (68).
Vol. 44, No. 10
Improvements in Ultrasonic Soldering Methods for Aluminum.
Last year, a soldering iron having a bit which wm ultrasonically vibrated was introduced commercially. This year there ie a second type introduced. A emall electrically heated, ultrasonically vibrated solder container replaces the bit (83,25, 34) Fundamental Study of Soldering Processes. Ail investigatiori of the factors that control the flow of liquid metals on bolid metal surfaces has been undertaken t o better understand soldering brazing, and hot-dip coating proceeses ( 3 , 4). This study yielded some interesting results. One of them w a y an explanation d why various solder tests, such as the spreading drop test and thr capillary penetration test, place solders in diff went orders of merit Another was evidence that soldering fluu deposits tin dectro lytically on the metal surface ahead of the advanring molfrr, solder. New Solder Alloys and Noncorrosive Fluxes. A tin-baht aluminum solder containing zinc, cvrium, and aluminum has beer) patented ( 1 6 ) . The cerium and aluminum addiiioiis increahi the corrosion iesistance. Pat on noncoi rosive h u e s haw also been issued (40, 84). Improved Soldering Methods. 4 solder pot M ith provision t t r i removing surfacp dross has been patented (97). TXN-COi’4TAIYI%G. R14T EKIALS
COURTESY U. S. STEEL CORP.
Figure 3.
Continuous Furnace for Fast Annealing of Tin Plate
The Japanese have studied the corrosion of tin in nitric acid solutions (37). Their work indicated that tin remains passive in solutions containing more than SO% nitric acid. HOT-DIP COATING METHODS
h unique method of produring ductile galvanized coatings on strip has been patented ( 7 6 ) . The strip is first passed through a molten lead-tin alloy and then through a molten zinc bath which is floating on and in contact viith the lead-tin bath. Details of hotrtinning wire have been clarified in a recent artirlcl (64). SOFT SOLDERS
Soft Soldering Ceramics to Metals. Metals can be joined to ceramics directly by means of metal hydrides, titanium hydride, being outstanding in its ability to make good joints. The method recommended in published articles has been to apply titanium hydride to ceramics and then braze to metals or similarly prepared ceramics with silver or any other brazing alloy having a melting point around 1000° C. It is not generally realized that many of the so-called soft-Le., low melting-solders will work equally well with the hydride process (10). Tin, lead, and indium form the bases for the solders used in this application. These low melting metals are extremely ductile, thus allowing the joining of part? that have radically different expansion coefficients. Joints made with these alloys are universally strong, and if properly made, are csompletefy vacuumproof.
lmproved Aluminum Tin-Bearing Alloys. Thc ttlumniuiil tin-bearing alloys in present commercial use do no1 contain nioi ( than 770 tin because higher tin contents make the alloys brittlr, This is a serious dram-back. Further additions of tin t o thcit aluminum tin-beai ing alloys continuously increase their scuffing resistance. A recent devdopment is the production of ductilc aluminum tin-bearing alloys having tin contents 01 30% an(! more (47). These alloys seem to offer a combination of the good embeddability and softness of babbitt with many timea the fatiguiresistance of babbitt. Bearing testsare hring run to confirm them indications. Hardenable Pewter and Britannis Metal Alloys. Ai hardellable pel\ ter has been developed which Foftens during working and can later be fully hardened by heat tiratmcnt a t a relativel) low temperature (89). This nen alloy has been developed to hold distortion of pewter more to a minimum. The alloy contains 1’/2% bismuth in addition t o the usual poi tions of anfimony and copper. I t also contains 0.170 phosphorus to prevrvir staining during the hardening heat treatment. New Patents on Tin-Containing Materials. Patents have bcw granted on a new graphitic nickel tin-bearing alloy (SO), 01 organic tin compounds for inhibiting corrosion in dielectrics (30) and on improved tin-coated collapsible tubes (45). Bronzes. The recent critical shortage of nickel which ~k urgently required for armament purposes (and for which there Ez no substitute) has brought about the need for replacemenb where they are feasible. One such application is the use ai: 10% tin bronze for condenser tubes t o replace the ‘70-30cupronickel commoiily used for this purpose. A recent review of 15 years oi research on this shows that tin bionze is not only equivalent to cupronickel in corrosion iesistance but is superior so far as resistance to impingement is concerned (96). Recent k s t k by the British Admirality bear this out (80). New precipitation hardening copper-tin-beryllium alloys have been studied ($4). This study is not yet finished but a practical aspect is the marked reduction in amounts of the expensive bervllium necessary to achieve high strengths. Another newsworthy development in bronze are the new “stamp pads” made from porous bronze plate (74). There has been a need for a concise, yet complete, compilation of pertinent data on the commercial wrought phosphor (Le.?tin) bronzes. An excellent one appeared during the year (88). Analyses of Tin-Containing Materials. One of the neccxsar) chores in specifying and utilizing construction materials is checking to make sure the material. measures up to sprcificationc
INDUSTRIAL AHD ENGINEERING CHEMISTRY
October 1952
New and revised methods for sampling and analyzing tincontaining alloys (1,79) and tin ingots (76) have been published. A new spectrophotometric method for determining bismuth in tin- and lead-base alloys has been developed (8). BASIC RESEARCH
h hile basic research is the starting point of subsequent engi-
I
iieering developments, the field is so extensive and varied that only the briefest mention of those relating t o tin can be made here. Measurements of physical properties of tin were among the tundarnental studies reported this year. These covered the following properties of tin: surface tension (41), specific heat (63), heat of fusion (6), internal friction and grain boundary viscosity (77), radioactivity (If, 1 f , 46, 58, 64), superconductivity (63, I O d ) , and magnetic susceptibility (of gray tin) (15). Crystal structures also received attention. Studies of the crystal structure of tin (70, 86),of tin-lead eutectics (loo),of tintitanium compounds (79, ZS), and of tin-antimony alloys undergoing creep (9) have been made. Phase transformations in copper-tin alloys have been investigated (19, 96). A particularly interesting paper was the study of the solidificationof lead-tin alloy droplets (55). Other miscellaneous research subjects included the oxidation of eoppcr-tin alloys (17), the synthesis of tin tetraiodide (69), the preparation of selenium derivatives of stannonic acids (86),and tin ~.I~.ctrocrystalliaation studies (61). RECLAMATION AND REFINING
\Cith some justice, it might be Maid that the subject ot reclamation hardly belongs in a materials of construction review. Yet from the point of view of conservation, perhaps it does. If so, its handmaiden, refining, must also be considered. This year, in the literature on reclamation, articles appeared on two items which are of interest here. One dealt with the details of operation of a new detinning installation of Weirton Steel Co. to handle secondary material from their tin-plate mill (66, 81); the other covered a method of separating tin from copper in a bronze using a stream of hydrogen chloride (93,94). In the field of refining, patents have been granted on the following new methods: freeing tin from lead (81), recovering tin as tin bulfide from low grade unreduced tin ore (68),and extracting tin from ores by reduction in a shaft furnace (51). A description of the electrolytic sodium sulfide-refining procem for crude tins containing as little as 70% tin has appeared (57). The reactions of hydrogen with tin oxides and sulfides have been .tudied (43). New developments in the beneficiation of tin ores inc*ludeflotation studies on cassiterite ( 1 4 , 31) and a description of beneficiation practice a t an Australian mine (29). LITERATURE CITED (1)
Allen, W. S. (to U. 8.SteelCo.), U. S.Patent2,522,920(May 16,
1951). (2)Am. SOC. for Testing Materials, “Methods for Chemical Analysis of Metals,” Philadelphia, Pa., 1950. (3 Bailey, G. L. J., Brit. Nonferrous Metals Research Amoc.. TN601B77R-RRA898 (January 1951). Bailey, G. L. J.. and Watkins. H. C., J . Inst. Metals, 80,57-76 (October 1951) (5) Balachandra, J., Current Sci. (India), 20, 99 (1951). (6)Bartenev, G. M.. J. Tech. Phys. (U.S.S.R.), 17, 1325-30 (1947). (7) Bell Labs. Record, 29,262-3 (June 1951). (8) Bendigo, B. B., Bell, R. K., and Bright, H. A., J . Research Natl. B u r . Standards, 47, 252-5 (October 1951). (9)Betteridge, W., and Franklin, A. W., J . Inst. Metals, 80, 147-50 (November 1951). (10)Bondley, R. J., Ceram. Age, 58, 15-18 (July 1951). (11) Bowe, J. C., and Axel, P., Phys. Rev., 84, 939-43 (1951). (12) Britton, S. C., J . Applied Chem., 1, Suppl. 2, S132-6 (1951). (13) Britton, S. C., and qngles, R. M., Metallurgia, 44, 185-91 (October 1951). (14) Bull. Inst. M i n i n g Met., No. 482 (May 1951).
.
2363
(15) Busch, G., and Mooser, E., 2. phys. Chem., 198, No.1 4 , 23-9 (October 1951). (16) Chadwick, Richard, and Heaton, W. G. (to Imperial Chem. Ind., Ltd.), U.5.Patent 2,552,935(May 15, 1951). (17) Cheater, A. E. (to Poor & Co.), Ibid., 2,548,867(April 17,1951). (18) Coe, E.S., I r o n Age, 167, 86-8 (June 14, 1951). (19) Colearat, Robert, Gence, Pierre, Buidlet, Leon, and Portevin. Albert, Compt. rend., 232, 1041-2 (March 12, 1951). (20) Compton, K. G.,Mendizza, A,, and Arnold, S. M., Corrosion. 7,327-34 (October 1951). (21) Cork, J. M., Stoddard, A. E., Branym, C. E., Childs, W.J., Martin, D. M., and Le Blanc, J. M., Phys. Rm., 84, 596-7 (1951). (22) Criwford, A. E.,Light Metals, 15, 1024 (March 1952). (23) Crawford, A. E.,Metallurgia, 44, 113-6, 121 (September 1951). (24) Cresswell, R. A., and Cuthbertson, J. W., Trans. Am. Tnst. M i n i n g M e t . Engrs., 191, 782-91 (1951). (25) Cuthbertson, J. W., J . Electrodepositors’ T’ech. Soc., 26, Preprint, 99-106 (1950). (261 Cuthbertson, J. W., Metal Ind., 79, 87-90 (Aug. 3, 1951). De Carli, F., and Collari, N., Metallurgia ItaZ., 44, 1-5 (January 1952). Donelson, J. G., Natl. Lithographer, 58, 36-7, 83-6 (August 1951). Dunkin, H. H., and Blaskett, K. S., Commonwealth Sci. Ind
Research Organization and Mining Dept. Univ. Melbourne, O r e Dressing Invest., No. 390 (Oct. 19, 1950). Ea&, J. T., and Lee, G. L. (to International Nickel Co., Inc.). U. S.Patent 2,568,014(Sept. 18, 1951). Edwards, G.R.,and Ewers, W. E., Australian J . Sci. Research, 4,Ser. A,62743 (December 1951). Eilender, W., Metal Finishing, 50, No.3,7 3 4 (March 1952). Eilender, W., Werkstoffe u. Korrosion, 2, 289-92 (August 1951). Electronics, 24, 212-16 (September 1951). Electroplating, 4, No. 12,384 (December 1951).
Ellenberg, A. M. (to Monsanto Chemical Co.), U. 6. Patent 2,573,894(Nov. 6,1951). Endo, Hikozo, and Yokoyama, Goro, Sei. Rept. Research Inst. Tohoku Univ., 2, Ser. A, 63744 (1950). Everhart, J. L., Materials & Methods, 34,97-112 (Sept. 1951). Farmer, Q. B. (to Bethlehem Steel Co.), U. 8. Patent 2,654,943 (May 29,1951). Feldman, L. V. (to Continental Can C o . ) ,Ibid., 2,564,199(Aug. 14,1951).
Flugge, S. L., Food Eng., 23, No. 8 , 114-16, 158-9 (August 1951).
Foryst, J., Prace GEownego Inst. Met., 3, No. 4,307-27 (1951). Gallo, G., and Guorra, M. D., Ann. Chim. (Rome), 41, 51-60 (1951) . Gas Times, 69, 117-18 (Oct. 19,1951). Goffart, A. A.,U. S.Patent 2,551,116(May 1, 1951). Goldhaber, G. S., Mateosian, E., Coldhaber, M., Johnson G. W., and McKeown, M., Phys. Rev., 83, 480-1 (1951). Hardy, H. K..Liddiard, H. K., Higgs, J. Y., and Cuthbertson, J. W., Proc. First World Mat. Congr., 1951,457-82. Harris, A. W. (to American Steel & Wire Co. of New Jersey) U.S.Patent 2,543,365(Feb. 27, 1951). Hartwell, R. R., “Advances in Food Research,” Vol. 111, p 327-83, New York, Academic Press, 1951. Hartwell, R. R., Food Technol., 5,No. 10,402-8(October 1951).
Hartwell, R. R.,Proc. N.C.A. Tech. Sessions, Convention Issue, Inform. Letter, No. 1371 (Jan. 20,1952). Hayward, C. R.,and Wright, Livingstone (to New Enterpriseu, Inc.), U. S. Patent 2,547,939(April 10, 1951). Hill, R. W., and Parkinson, D. H., Phil. Mag., 43, Ser. 7,30916 (March 1952). Hoare, W. E.,Wire Ind., 18, 867-70, 873-5 (October 1951): 969-71 (November 1951). Hollomon, J. H.,and Turnbull, D., Trans. Am. Inst. M i n i n g Met. Engrs., 191,803-5 (1951). Tron Steel Engr., 29, No. 2,140 (February 1952). Jenson, C. W., M i n i n g Mag., 84,206-9 (April 1951). Kalkstein, M. I., and Libby, W. F., Phys. Rev., 85, 368-9 (1952). Koehler, E. L., Trans. A m . Soc. Metals, 44, 107f5-96(1952). Kolb, John, Iron Age, 168,No. 5 , 90-1 (Aug. 2, 1951). Krinkova, A. A., and Loshkarev, M. A.. Dokladu Akud N o S.S.S.R., 81, 1097-100 (Dec. 21. 1951). La Que, F.L., Corroszon, 8, 1 (Apri 119521 Lock, J. M., Proc. R o y SOC.(London), 208A, 391-408 (Sept 1951). McGinnis, C. L., Phys. Rev., 81,734-40 (1951). Mohler. J. B., I r o n Aae. 169. No. 6.139-41 (Feb. 7. 1952). Muhler, J. C., and Day, H . G., J . Nutrition, 44, No. 3.413.-21 (July 1951).
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INDUSTRIAL AND ENGINEERING CHEMISTRY
(67) Munns, J. J., Steel, 129, 102-4 (Dec. 17, 1951). (68) Muskat, I. E., and Taylor, R. H. (to the Vulcan Detinning Co.), U. S. Patent 2,585,161 (Feb. 12, 1952). (69) Nebergall, W. H., and Walsh, R. H., J . Am. Chem. SOC.,73, 4043 (August 1951). (70) Nicholas, J. F., Trans. Am. Inst. M i n i n g Met. Engrs., 191, 1142 (1951). (71) Parkinson, N., Britton, S.C., and ilngles, R. M., Sheet Metal Ind., 28,757-67,770 (August 1951). (72) Pietrokowsky, Paul, Tmns. Am. Inst. Mining M e t . Engm., 194,211-12 (1952). (73) Pietrokowsky, Paul, and Dewez, Pol, Ibid., 191, 272-3 (1951). (74) Plastics Ind., 9, 16 (April 1951). (75) Price, J. W., Plating, 39, h-0. 4, 344 (April 1952). (76) Renkin, R. F. (half to Roemer, H. A , ) , C. S.Patent 2,557,764 (June 19, 1951). (77) Rotherham, L., Smith, 9 . D. S . , and Greenough, G. R., J . Inst. Metals, 79, 439-54 (August 1951). (78) Scherber, H. E., Farbe u. Lack, 55, 370-2 (1949). (79) Scribner, B. F., and Ballinger, J. C., J . Research jVat2. Bur. Standards, 47,221-6 (October 1951). (80) Slater, I. G., Kennorthy, L., and May, R., J . Inst. iMetuZs, 77, (1950). (81) Societe d'electrocheniie, d'electrometallurgie, e t des acieries electriques de Ugine, French Patent 965,971 (September 1950). (82) Steel, 130, No. 4, 7G-2, 74 (Jan. 28, 1952). (83) Stone, -M. D., and Randich, E. A., Metal Progress, 62, 62-6 (February 1952). (84) Stright, B. hl. (to General Railway Signal Co.), U. S. Patent 2,581,820 (Jan. 8, 1952).
Vol. 4, No. 10
(85) Tchakirian, Arakel, and Bevillard, Pierro, Bull. sac. chim. France, 1950,1300. (86) Teghtsoonian, E., and Chalmers, Bruce, Can. J . Plzys., 29, 370-81 (September 1951). (87) Thews, E. R., MetalEoberflache, 4, Ser. B, B5-6 (January 1952). (88) Tin Research Inst., Tin and I t s Uses, Xo. 24, 11-12 (July 1951). (89) Ibid., Yo. 25,2 (December 1951). (90) Ibid., p. 3. (91) Ibid., p. 9. (92) Ibid., No. 26, 6 7 (May 1952).
(93) Trautzl, Peter, and Treadwell, W. D., Hell;. Chim. Acta, 34, 1723-31 iOct. 15.1951). (94) Trautzl, Peter, and Treadwell. IT. D., 2. SaturJorsch., 66, 22932 (July-August 1951). (95) Trimble, J. R., and Hill, J. E., Iron Steel Engr.. 28, KO.4, 70-3 (1951). (96) TT-ang, C. C., and Hansen, hI., Trans. Am. Inst. Mining Met. Enars.. 191. 1212 (1951). (97) Wairen, G. G. (to American Elec. Furnace), U. S. Patent 2,579,634 (Dec. 25, 1951). (98) Khite, A. M., Metal W o g r e s s , 60, 7s-80 (December 1951). (99) Wilson, 3. K., and Wright, O , Electroplatznn and M e t . F t n ~ s h i n y , 4,274-6 (September 1951). (100) Winegard, W.C., hIajka, S., Thall, B. M., and Chalmere, R., Can. J . Chem., 29,320-7 (1951). (101) WireInd., 18,885 (October 1951). (102) Zavaritskii, iX. V., Doklady Acad. Kauk S.S.S.R., 78, 665-8 (June 1, 1951). RECEIVED for review August 1, 1952.
-4CCEPTED A 4 U g U S t 4
, 1952.
Less Common Metals L. F. YSTERIA AND WILFRED R. BEKERREDE Fansteel lT&ietallurgicaE Corp., Y b r t h Chicago, I l l .
acid and by sulfuric acid, 50 to 100% between 65' and 150' C. Waber. Sturdy, Wise, and Tipton (143) have studied the oxidation of tantalum over the range of 220' to 350" C. Up to 320' C. the rate is logarithmic; above this temperature i t is parabolic. Ramage (123) developed a procedure for coating the surface of tantalum in order to protect it from oxidation at elevated temperatures I t consists of electroplating t h e t a n t a l u m with chromium, followed by a heat treatment in a hydrogen atmosphere at a temperature sufficient to form a eutectic between the chromium and the tantalum. Wensch, Bruckart, and Conolly (144) evaluated several methods of electropolishing and electroetching tantalum. They recommend a solution containing 90 parts (by volume) of concentrated sulfuric acid and 10 parts of concentrated (48%) hgdrofluoric acid, a graphite or platinum cathode, and a temperature of 35' t o 45" C. The current density should he 0.10 ampere per square centimeter for electropolishing and 0.02 ampere per square centimeter for electroetching. The physical properties of tantalum are revieTed in a bihliography compiled by Sachs (128). The microstructure and thermal expansion of tantalum have been investigated by EdTYards, Speiser, and Johnston (44). Yntema (147) described the work done on coating tantalum onto a base metal by reducing a tantalum halide with hydrogen
T h e use of a less common metal as a material of construction is suggested by a unique property or combination of properties, such as w-orlrability or resistance to chemical attack. The noble metals and tantalum have retained their positions of importance i n the chemical industries because of characteristics that fit them for many applications. The continued interest i n titanium, based o n its low density and high strength, is reflected i n the stress being laid on the economics of its reduction. Information has been accumulated on the properties of its alloys and on the working and fabrication of both alloys and the pure metal. In the case of zirconium the importance of purification is indicated by the publication of data o n the effects of small amounts of oxygen, nitrogen, carbon, and hafnium on its corrosion resistance and in the investigations directed toward improving melting techniques used i n its production. The molybdenum literature is concerned with its use and properties at high temperatures. Protection against oxidation is described. Data have been published o n alloy systems. The literature on the noble metals discusses their use i n the chemical industries, their physical and chemical properties, and a series of alloy systems.
HIS revieiv of the past year's literature on the less common metals as materials of construction is divided into sections on tantalum, titanium, zirconium, molybdenum, and the iioble metals. TAYTA L U M
The corrosion resistance of tantalum to 70 commonly handled organic materials, inorganic salts and acids, and free halogens is reported by Percy (119). There is no attack a t all up to 150" C. except by fluorine, hydrofluoric acid, fluosilicic acid, fuming sulfuric acid, sulfuric acid, aad phosphoric acid. The rate of attack of the fluorine compounds and fuming sulfuric acid is of the order of 0.05 inch per year at all concentrations from 0" to 150" C. .It is attacked a t the rate of 0.005 t o 0.02 inch per year by phosphoric
