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Tin and Its AIIoys by Robert M. Maclntosh, Tin Research Institute, Inc., Columbus, Ohio N e w tin alloys, new techniques for using tin more efficiently, and a vast amount of basic knowledge about tin-containing materials have resulted fro m w or1d -wide investig at ions
THE age-hardening nary cobalt-tin and
b
Basket plating of delicate wires and parts is a boon to transistor and semiconductor manufacturers
b
Tin is advantageous in removing oxygen and nitrogen from titanium-base alloys
or
properties binickel-tin alloys, containing u p to 20Oj, tin, have been studied. For both series of alloys, the tin has a hardening effect on the matrix of the cast and solution-treated alloys. The addition of tin to titanium-base alloys counteracts the harmful effect of interstitial impurities, such as oxygen and nitrogen. This effect has considerable commercial importance, as there is no known method of removing these impurities from titanium. Studies of phase diagrams of tin-zirconium and tin-titanium show that tin forms compounds of high melting points, such as Zrg Sna, which melts a t approximately 2000’ C. Powder metallurgy methods are a likely means of preparation. Methods of assessing the quality of tinplate based on the accelerated corrosion of tinplate by fruit juice has shown that a sharp increase in rate of solution of iron occurs when a critical area of the steel base is exposed. This occurrence is associated with a fall in the current density on the exposed steel generated by the tin-steel couple. The American Welding Society published a soldering manual. This is a comprehensive treatment of soldering processes, techniques, solders, and fluxes. The director of the International Tin Research Council, with the collaboration of a group of authors from the Tin Research Institute, edited a book on tin and its alloys. This practical book covers the physical, mechanical, and chemical properties of tin and applications of tin in the alloy field. Bearing alloys, die-casting alloys, type metals, solders, and bronzes are also covered. A new process called “flat basket plating” was specifically developed for plating small delicate parts with a cop-
per-tin alloy coating. The procedure is applicable to the plating of single metal deposits. Tin plating and tin alloy-plating electrolytes and processes continue to attract more attention as practical solutions for decorative and protective applications and as an aid in fabrication. The corrosion resistance of the tin and tin alloy coatings in industrial atmospheres, under humid and tropical heat and in contact with foods and beverages, was the subject of several investigations. Alloy development of binary and ternary tin alloys and the determination of physical, mechanical, and electrical properties of the alloy systems resulted in a wealth of new information. Inorganic and organic tin compounds found use as catalysts and intermediates for many industrial products and processes. Practical advances were made in the use of tin-containing coatings for conductive glass and panelescent lighting. Further developments were published on the benefits of tin additions to nodular iron and cast iron. A new process of thermite welding with aluminum powder and tin oxide was announced. Special tin alloy anodes simplify the process of chromium plating gear teeth. Many improvements in bronze casting practices and studies to prevent segregation and improve properties were reported. Semiautomatic production of cored solder wire from billet to finished product was described. Zone refining of tin, growth of whiskers, and single crystals created considerable attention. The development of binary and ternary systems and studies of their properties continued to hold the interest of investigators.
General The annual report of the International Tin Research Council (4A) reviewed the conferences, lectures, and technical committee work in which the staff participated in 1959. Current research studies deal with hot tinning, tinplate, electrochemistry, and corrosion ; alloy developments in cobalt, nickel, and titanium-tin alloys, soldering fluxes, and tin chemicals. The Tin Research Institute staff in London and the staff from the seven branch offices published 37 original research papers, booklets, and technical articles dealing with tin. The majority of these published works are available from the Institute. The addition of 15% tin to titanium increased the ultimate tensile stress a t room temperature approximately 90% with a corresponding, though less marked, reduction in ductility ( 7 A ) . Electrodeposited tin coatings when flowmelted in oil have improved appearance and remain solderable indefinitely. A practical manual describes the technique and selection of flow-brightening oils that are available (8A). A complete review of the advantages of tin for modifying cast and nodular iron ( 3 A ) , recommendations for a new flux vehicle for soldering ( 5 A ) , and the benefits of hot tinned coatings for corrosion protection were discussed (IOA). A conductive film of tin oxide anchored to the silica network in the surface of glass has been usefully applied to prevent icing on airplane and automobile windshields. Glass flasks, with conductive areas on their bases, can be used in the laboratory. Glass with a conductive coating can be used on windows of instruments to leak away static VOL. 52, NO. 11
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Panelescent lighting, which utilizes tin-containing coatings, is ideal for passenger signs on the Comet 4
An automatic process for tin plating steel drums has been developed. T h e steel containers are formed by flashbutt welding, and the side seam is smoothed with pressure rolls. Plating in a stannate bath is followed by flowbrightening in an oil bath. Drums are used for bulk handling of food products (21C). A new method for tin-alloy plating delicate parts in bulk is achieved using a framenrork of stainless steel wire as a basket to hold the parts. The baskets are poly(viny1 chloride)-coated, except the two longitudinal conductors which carry current to the work. 4 n outer framework holding four baskets equalizes current distribution. Plating of 600:OOO leads for quartz crystals per eight-hour shift is possible (792). Development of tin-alloy systems for aircraft engines was based on the need for coatings with low sliding friction, high corrosion resistance, wear resistance, and heat resistance. Cadmiumtin meets the need for corrosion resistance. Tin-bronze coatings containing 5 to 15% tin have simplified nitriding operations. A deposit containing about 5% copper in a tin matrix has shown promise of good wear qualities. A silver-tin deposit was found useful in sleeve bearing applications whcre hardness slightly greater than silver is needed (28C). A method is described for clcctroplating porous materials, such as sintered bronze. Deep impregnation with oil prevents entrapment of elec~
charges. When the conductive glass is in contact with a phosphorescent material and voltage is applied, colored illuminated panels suitable for signs on aircraft operate without heating the glass. A 100-square inch panel may consume only 3 watts 19A). The performance of tin-nickel plating under corrosive conditions approaches that of the precious metals. Industrial applications for the coating were cited for the electronic, scientific instrument, household appliance, and chemical industries ( 7 A ) . T h e developments in tin and tin plating processes over the last 50 years were reviewed ( 6 A ) . A practical book on tin and tin alloys was published ( 2 A ) .
Tinplate, Cans, and Packaging The British Iron and Steel Research Association’s (BISRA) report on tinplate research briefly describes progress in continuous hot-dip tinning. marking of differentially coated plate with a thin electrodeposit of iron, electrically smoothing blackplate before tinning to improve rust resistance, and bonding of poly(viny1 chloride) plastic film to tinplate and steel strip (20B). T h e world’s first six-stand cold reduction mill with speeds u p to 7250 feet per minute will be used to roll light-basis weight plate (27B). -4 highly uniform, continuously annealed strip is obtained if the annealed strip is immediately cold reduced and the amount of reduction is used as a means of adjusting the furnace conditions (22B). There are advantages in using multiline. 60-ton-per-hour continuous annealing furnaces. T h e single pass, direct-fired moderate speed installations assure uniform quality ( 7 B ) . Tinplate is effectively oiled for ease of handling without abrasion by application of a thin coating of bis(2-ethylhexyl) sebacate amounting to 0.05 to 0.5 gram per A refined cottonseed base box (72%). oil containing 1 to 47; of a mixture of
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mono- and diglycerides is a suitable protection for tinplate against scratching and oxidative deterioration (7B). Methods of finishing tinplate and the materials used were reported (75B). Xew developments in can manufacture irere reviewed. Coil processing, new interior coatings, chemically treated plate, beaded cans, and bulk palletization were discussed ( 4 B ) . T h e problems of handling 10-ton coils require special equipment such as 70-ton gondola cars, electric fork-lift trucks, and a magnetic coil upender (19B). T h e first production of coiled stock in England was briefly described (13B). Can seaming costs are cut drastically if chromium is diffused into the surface or the seaming rolls to increase wear resistance (8B). Italy now has three plants producing tinplate (77B). Considerable progress has been made in applying the differential type of electrolytic plate to the canning of special food products (7623). T h e mechanism of corrosion of tinplate by various food products was studied and found to be a function of the food product (QB). Corrosion is controlled by product modification? container material selection, storage conditions, protective coatings, and treatments (2B, 3B, 5B). Corrosion problems in canning carbonated beverages are perforations and excessive iron pick-up. Best solution was limiting the galvanic current in the can by reducing corrosivity of beverage and control of metal exposure in can fabrication (74B, 78B). Evaluation of tinplate and organic coatings for food cans was described (6B). Colored spot defects on tinplates were traced to a thin oxide layer which appears on annealing. The oxide is difficult to remove by etching but is removed by polishing (77B). Obstacles to the use of aluminum cans in volume for processed food products are many. Heavier gages are needed to prevent paneling and buckling. T h e stronger magnesium-containing alloys drastically reduce shelf life ( 706’).
INDUSTRIAL AND ENGINEERING CHEMISTRY
New procedure for plating delicate parts in bulk utilizes special baskets, shown here on carrier rack
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trolyte (70C). Electroplating over soldered surfaces requires special cleaning procedures (7C, 73C). T h e use of ultrasonics in tin plating steel strip gives a smooth bright finish (2GC). T i n and tin alloy electrodeposits on ferrous a n d nonferrous basis metals were rated according to corrosion resistance a n d shelf life (72C, 22C). Exposure tests on tin-nickel coatings a t K u r e Beach have been in place two years with only slight signs of tarnish. Tests have been in place four years in the industrial areas of Pittsburgh and Bayonne with no sign of attack ( 78C). A high zinc-low tin alloy coating is solderable (25C), the anodes can be maintained in a polarized state (3C), and finger staining can be prevented (24C).
Electrodeposition Studies pertaining to electrodeposition are listed in Table I.
Courtesy: Bethlehem Steel Corp.
These 5000-pound tin anodes are being cast for electro tinplate production Electrodeposition of Tin and Its Alloys Subject Ref. Chemical plating of Sn on (6C)
Table 1.
cu Sulfamate bath for tin plating Rapid tin platinq- solution or process Electroplating on T h Investigation of Pb-Sn plating Ag-Sn alloy plating Addition agents for alkaline tin plating Electropolishing of Sn alloys Tin plating from fused salt baths Flow melting of Sn coatings Polarization and corrosion of
Sn Tin plating on readily oxidized metals Electroplating on A1 wire Electroplating printed wiring Casting Sn anodes for electro tinpiate Plating Sn-Ni from organic electrolytes
(77C) ( 76C, 3 2 C )
(4C) ( 74C) (23C
(26‘2)
(29C) (3UC, 37C) (7C)
(2C) (75C, 2 7 C )
(9C) (8C) ( 77C)
(5C)
Solders, Soldering Practices, Joining T h e American Welding Society through its Committee on Soldering a n d Brazing published a comprehensive soldering manual. T h e book covers the principles of soldering, solders, flux compositions, and soldering processes. Chapters are devoted to the joining of all the common ferrous and nonferrous basis metals ( 2 0 ) . T h e composition, properties, a n d applications for solders have been given careful study (30). Special techniques have been given for soldering aluminum and appraising the performance of the joints (50). Precoating aluminum prior to soldering is
accomplished by dipping in a two-layer liquid. T h e lower layer is a solution of fluosilicic arid, the upper layer a solution of activated rosin in alcohol ( 4 0 ) . Aluminum can be coated with fusible alloys by immersion in a molten solder bath covered with a zincate of an alkali metal (370). Soldering fluxes for aluminum (60, 790), a flux for soldering radiator cores ( 7 6 0 ) a n d electric-lamp base shells (IOD), a n d fluxes for noncorrosive applications ( 7 7 0 , 1 5 0 , 770, 260) were enumerated. A flux additive compound, which changes color on heating, has been suggested for flux residue control (300). A semiautomatic process for the production of cored solder wire includes the casting of billets, extrusion press a n d die design, wire drawing, and packaging (280). T h e brazing of articles for use a t high temperature with a filler metal containing 20 to 3070 tin, 60 to 70% nickel, chromium, and silicon gives joints that resist intergranular penetration or embrittleinent after 4.00 hours a t 1300” F. (70-90). T h e requirements and performance of special solders for nuclear a n d space environments have been discussed ( 7 2 0 , 270). When added to solder. an absorptive substance with “black body” characteristics, such as graphite, improves the performance of the solder under infrared heating (200). Alumin u m a n d uranium can be bonded with tin, zinc, a n d lead solders if a diffusion barrier layer of copper is applied to the aluminum a n d a nickel coating
is applied to the uranium ( 1 8 0 ) . T h e mechanical properties, strength behavior, a n d reliability of soldered joints have been discussed ( 7 0 , 730, 2 7 0 ) . Theoretical considerations regarding wettability, solidification characteristics, capillary spacing, a n d heating processes have been reviewed (220-250). Applications of rare a n d noble metals in soldering of semiconductors have been discussed ( 7 4 0 ) . T h e solderability of various coatings of tin, of alloys of tin with lead, zinc, and cadmium were compared after storage u p to two years. T h e program involved 8000 specimens. T h e influence of coating thickness, basis metal, a n d undercoat layers was studied. Recommendations were made for achieving high initial solderability a n d retainment of solderability during storage ( 2 9 0 ) .
Bearings A guide to the selection of bearings a n d types to use for various applications has been given. Emphasis is on externally pressurized bearings in machine tool applications (2E) a n d bearing alloys for the p u m p industry ( 7 E ) . Highest bond strengths are obtained by roll bonding aluminum-tin bearing alloys a t room temperature ( 3 E ) . T h e quaJities of aluminum-tin alloys as antifrictional bearings were discussed (4E, 5E). Procedures were given for the surface preparation of cast iron and steel before babbitting to improve bond strength (6E-8E). VOL. 52,
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Table II.
Bronze Research
Subject
Ref.
Effect of Pb and other impurities on tensile properties of Ni-Sn bronze sand castings Choosing correct gun metal for each application Tapered chills for pressure tight castings Alloys for marine propellcrs Running, gating, risering, and melting practices Microstructure and fracture characteristics of 85-5-5-5 gun metal Design and operating conditions for bronze sleeve bearings Physical properties of bronzes with fine structure Recrystallization behavior Creep properties Electrical conductivity Phase transformations Relationship between hardness and resistance to seizure Surface tension of commercia1 bronzes Growth of Cu-Sn powders during sintering
(2G)
T h e structure and phase constitution of hot tinned coatings on steel have been investigated ( 6 F ) , as well as the use of radioactive isotopes in studies of the mechanism of hot dip tinning (77F). A method for tinning readilv oxidizable metals by immersion in fused salts requires no electric current or reducing agent ( 9 C ) . New equipment is capable of annealing and tinning copper wire in one process ( 8 F ) . A new tinning oil consists of palm oil plus a n organic additive (7F). Y
( 8 G , 75G, 2lG)
(QG,70G, 13G) ( 77G, 78G)
Bronze Research (14G, 79G, 20G)
Table I1 contains a listing of investigations on bronze.
Corrosion Research
(6G)
Tin-zinc, tin-cadmium, and tin-bronze alloy coatings are recommended for protection against corrosion under severe conditions (7H, ZH, 4H: SH, IOH). Corrosion tests have been made on tin coatings a t three industrial sites (3H, SH). -The nature of the corrosion product of tin ( S H ) has been studied. Corrosion inhibitors are available for reducing galvanic attack in automotive radiators (7H, SH, I I H ) .
Hot Tinning Practices
A suggested strip tinning device has applicator disks mounted on shafts positioned above the level of the molten tin. T h e device can also apply zonal bands of tin to the strip (IOF). Application of a thin alloy layer to thin gage steel was described (7F), as were hot d i p tinning of cast iron (2F-4F) and control of impurities in the tinpot
(5F).
Practica I Develop ments Applications of tin and its alloys of practical significance are listed in Table
111. Basic Research Fundamental investigations of tin and its alloys are outlined in Tables IV and V.
Table
V.
Alloy
Developments
Properties Subject Binary Alloys Thermodvnamics of Bi-Sn system Sn transformation in Sn-Hg alloys Structure of oxide films on molten Pb-Sn alloys Electrical resistance of AuSn alloys Effect of slow cooling on SnBi and Sn-Cd alloys Cellular growth in Sn alloys Heat of combination in NaSn system Atomic distribution in liquid Sn-Sb alloys Thermodynamics of the PbSn system Diffusion in the Sn-Hg sys-
and
Ref.
(J2L)
v
t em
Reflectivity and structure of Cu-Si1 and Au-Sn films Creep of Pb-Sn alloys Grain boundary migration in zone refined Pb containing Sn Electrical properties of SnSb system High strength Zr-Sn alloys Zircalov 2 Corrosion: mechanical, and physical properties Creep properties Redistribution of Hz under thermal stress Diffusion of Oa at high temperature Plastic flow Effect of impurities in Ti-Sn alloys Structure of liquid Au-Sn allovs Struc Baird, D. C., Can. J . Phys. 37, 937-43 (August 1959). (4K) Bonar, L. G., Craig, G. B., Zbid., 36, 144-5-9 (1958). (5K) Erdmann-Tesnitzev, F.: Schubert, T., iVeue Hiitte 4, 359-65 (1959). (6K) ELvald, A. UT.> Tufte, 0.S , , “Advances in Semi-Conductor Science,‘’ Pergamon Press: New York, 1959. (7K) Holmes, E. L.. M’inegard, W’. C., Acta M e t . 7, 411-14 (Junc 1959). (8K) Holmes, E. L., M’inegard, W. C., Can. J . Phys. 37, 496-8 (1959). (9K) Honeycombe. R. W .K., M e t . R e ~ s . 4, No. 13, 1-47 (1959). (10K) Ivannikov, A. S., Egorov, A. M., Balmakov: A. Yu.: Russ. Patent 118,981 (March 25, 1959). (11K) Koyama, M., Bull. Znst. Chem. Research Kyoto L’ninic. 36, No. 43, 49-61 (1959). (12K) Parr. N. L.. A’ew Scientist 5 , 290-2 (Feb. 3, 1959). (13K) Pelzel, E., Galvanotechnik 50, 211 (April 15, 1959). (14K) Speiwak, M . , Unizl. Chicago Inst. Study M e t a l s Quart. Refit. 10, No. 51, 381-411 (Drcember 1958). - (15K) Toye, T. C., Proc. Phjs. S O ~(London) . 73, Pt. 5, 807-10 (May 1959). (16K) Urazov; G. G., Lovchikov. V . S.; Lipshits, B. M., Izuest. TJysshikh Ccheb. ZauenieniT: Tscetnayo Met. 4, 96-102 (1958). (17K) Zernov, V. B.: Sharvin, V . Yu., Zhur. Ekcptl. i T m r p t F i t . 36, 1038-45 (1959). (1K) Anastasiadis,
\
Alloy Developments a n d Properties
(1L) Aust, K. T., Rutter, J. W., Trans. A m . Znst. Mining, M e t . , Petrol. Engrs. 215, 119--27 (February 1959). (2L) Zbid., pp. 820-31 (October 1959). (3L) Bangert, L., Z . Metallk. 50, 269-74 (1959). (4L) Cheng, C. S., Wu L i Hsiieh Pa0 14, 346-53 (1958). (5L) Zbid.: pp. 393-9. (6L) Cheng, C. S., Lee, Y. L.: Tung Pei Jen iMin T a Hsiieh-Tzu Jan K’o Hsueh Hsiieh Pa0 1957, pp. 35-44. (7L) Fujiki: Y., J. Phys. Soc. Jafian 14, 913-17 (July 1959).
INDUSTRIAL A N D ENGINEERING CHEMlSTRY
(8L) Gebhardt, E., Petzow, G., Z . rtletallk. 50, 597-605 (1959). (9L) Geguzin, Ya. E., Kudrik, V. I., Fiz. Metal i Mefallowd., A k a d . iliauk S.S.S.R. 7, 235-42 (1959). (IOL) Gerasimov, Ya. I., I\’ikols’kaya, A . V., Evseev, A. M., J. chim. phys. 56, 641-8 (1959). (11L) Grigorescu, L., Hollos, G.: others, ~~aturruissenschaiten 46, 258-9 (1959). (12L) Guenther, F., Jehmlich, J., Z. L14eLallk. 50, 288-93 (May 1939). (13L) Haynes, R., Bidmead, G. F., J . Inst. Metals 87, 136-40 (.Jan. 1959). (14L) Holden, F. C., Douglass, R. IV., others. WADC Tech. Rept. No. 58-438 (December 1958). (15L) Jaffee, R . I., Ogden, H. R., Maykuth, D. J. (to Crucible Steel C o . ) , U. S. Patent 2,892,704 (June 30, 1959). (1 6L) Kendall, \V. B., Hultgren, R., J.Phys. Chem. 63, 1158-60 (1959). (17L) Kimura, R . , Planseeber. Pulzermct. 7, 50-66 (August 1959). (18L) Krebs, H., Haucke, M.. Weyland, H., “Physical Chemistry of Metallic Solutions and Intermetallic Compounds.” Vol. 2, Her Majesty‘s Stationery Office, London, 1959. (19L) Lashko, A . S.,Doklady Akad. :\’auk S.S.S.R. 125, 126-8 (January 1959). (20L) Mallett, M. W.:Xlbrecht, M. W., Wilson, P. R., J . Electrochem. SOC.106, 181-4 (1959). (21L) Markowitz, J. M.? U. S. Atomic Energy Comm. WAPD-TM-171 (.January 1959). (22L) Morachevskii, A. G., Lantratov, M. F., Zhur. Obshcher Khirn. 29, 2109~-.13 (July 1959). (23L) Pankaskie, P. ~ J , : L . S. Atomic Energy Comm. HW-59383 (Rev.) (March 25, 1959). (24L) Parr, N. L., Muscott. A.; Crocker, A . J., J . Znst. Metais 87, 321-9 (June 1959). &{ 1 (25L) Plaskett, T. S., Wincgard, W. C., Can. J.Phys. 37, 1555-7 (1959). (26L) Popov, A. .A,, Blyum, E. E., S a u c h . Doklady Vysshei Shkoly-&let. 1, 160-.4 (1959). (27L) Rayson, H. 5V.. Goulding. C . W., Raynor, G. V.: Metallur.gia 59, 57-62 (February 1959). (28L) Ibid., pp. 125-30 (March 1959). (29L) Robinson, H. ,A,: Doig, J . R., others, Trans. A m . Inst. -Mining, M e t . , Petrol, Engrs. 215, 237-45 (April 1959). (30L) Roll. A.: Uhl? E., .Z. .Metallk. 50, 159-65 (1959). (31L) Rubenstein, L. S., A-ucleonics 17, 72-6 (March 1959). (32L) Schubert, K., Briemer. H.. Gohle, R., %. A4etallk. 50, 146-53 (1959). (33L) Schubert, IC, Lukas: H. L., others, Zbid., 50, 534-40 (1959). (34L) Shimaoka, Goro; Trans. ;Ihtl. Znst. Metals 1, Yo. 1, 72 (1959). (35L) Smith, R. W.;Can. J. Piz~s. 37, 1079-84 (October 1959). (36L) Stadelmaier, H . H., Huetter, I,. J., Acta M e t . 7, 415-19 (June 1959). (37L) Suganuma, Ryoji, J . Phys. SOC..Jafian 14, 685-6 (1959). (38L) Tanner, L. E.: Levinson, D. W., Trans. A m . Soc. Metals 52, Preprint No. 166 (1959). (39L) Ustianov, V. I., SozJiet Phys.-Tech. Phys. 3,1106-10 (June 1958). (40L) Vyatkin, A . P., Zzve.\t. Vysshikh Ucheb. ZatiedenirFiz. 2, 48-52 (1959). (41L) Wagner, R. K . , Kline, H. E., U. S. Atomic Comm. NAA-Sr-3481 (July 15, 1959). (42L) Wittig, F. E., Huber. F., 2.physik. Chem. X e u e Folge 18, 330-47 (December 1958).
