Alloys containing lead

Tin - the atomic number is 50 and the chemcial symbol is Sn. The name derives from the Anglo-Saxon tin of unknown origin. The chemical symbol, Sn, is derived from the Latin stannum for alloys containing lead. The element was known in prehistoric times. 

Many tin alloys containing lead, copper, antimony, and bismuth were also in use in Marggrafs time. He mentioned three kinds of unalloyed tin first the Malaga, reputed to be the best, second the English, and third the Saxon and Bohemian (219). 

Lohberg, K. (1945-1946). Series of articles Investigation of corrosion by steam/moist air/water on zinc/aluminum alloys containing lead, in Metall forschung. 

Soldering and brazing alloys containing lead, zinc, or cadmium should be used with proper ventilation. The noble metals themselves present no direct problems because the reactive osmium is not used in these alloys. 

Topic of the search is alloys containing lead and gold, other elements are permitted, too. 

SnAg3.0Cu0.5 217to 220°C Poorer wetting than alloys containing lead ... 

Solders are typically classified as either soft or hard. Some confusion often results from this convention because some hard solders are really braze materials if the melting temperature criterion is applied. Soft solders typically consist of alloys containing lead and tin, but also often contain indium (In), bismuth (Bi), antimony (Sb), or silver (Ag). In practice, most soft alloys melt at temperatures lower than 450°C, usually between 180°C and 300°C. High-tin solders, typical of lead-free solders, tend to be stiffer, harder, and less ductile compared to high-lead solders. Hard solders often contain metals such as Au, Zn, Al, and Si. 

Automobile battery grids employ about 1—3 wt % antimony—lead alloys. Hybrid batteries use low (1.6—2.5 wt %) alloys for the positive grids and nonantimony alloys for the negative grids to give reduced or no water loss. The posts and straps of virtually all lead—acid batteries are made of alloys containing about 3 wt % antimony. 

Anodes. Lead—antimony (6—10 wt %) alloys containing 0.5—1.0 wt % arsenic have been used widely as anodes in copper, nickel, and chromium electrowinning and metal plating processes. Lead—antimony anodes have high strength and develop a corrosion-resistant protective layer of lead dioxide during use. Lead—antimony anodes are resistant to passivation when the current is frequendy intermpted. 

Excellent antifriction properties and good hardness (qv) make lead—antimony—tin alloys suitable for journal bearings. The alloys contain 9—15 wt % antimony and 1—20 wt % tin and may also contain copper and arsenic, which improve compression, fatigue, and creep strength important in bearings. Lead—antimony—tin bearing alloys are Hsted in ASTM B23-92 (7). 

Low (2—5 wt %) antimony, low (2—5 wt %) tin lead alloys are used for automobde body solder. Special lead—antimony alloys containing 1—4 wt % antimony are used for wheel-balancing weights, battery cable clamps, collapsible tubes, and highly machined isotope pots. 

Lead alloys containing 0.09—0.15 wt % calcium and 0.015—0.03 wt % aluminum are used for the negative battery grids of virtually all lead—acid batteries in the United States and are also used in Japan, Canada, and Europe. If the molten alloy is held at too low a temperature, the aluminum precipitates from solution, rises to the surface of the molten alloy as finely divided aluminum particles, and enters the dross layer atop the melt. 

Wrought lead—calcium—tin alloys contain more tin, have higher mechanical strength, exhibit greater stabiUty, and are more creep resistant than the cast alloys. RoUed lead—calcium—tin alloy strip is used to produce automotive battery grids in a continuous process (13). Table 5 Hsts the mechanical properties of roUed lead—calcium—tin alloys, compared with lead—copper and roUed lead—antimony (6 wt %) alloys. 

Only lead alloys containing copper below 0.08% have practical appHcations. Lead sheet, pipe, cable sheathing, wine, and fabricated products are produced from lead—copper alloys having copper contents near the eutectic composition. Lead—copper alloys in the range 0.03—0.08 wt % copper are covered by many specifications ASTM B29-92 (7), QQL 171 (United States), BS 334, HP2 Type 11 (Canada), DIN 1719 (Germany), and AS 1812 (Austraha). 

Lead—copper alloys are the primary material used in the continuous extmsion of cable coverings for the electrical power cable industry in the United States. Other alloys, containing tin and arsenic as well as copper, have also been developed for cable sheathing in the United States to provide higher fatigue strength. 

Extmded or roUed lead—copper alloys contain a uniform dispersion of copper particles in a lead matrix. Because the soHd solubiUty of copper in lead is very low, copper particles in the matrix remain stable up to near the melting point of lead, maintaining uniform grain size even at elevated temperature. 

Copper-containing lead alloys undergo less corrosion in sulfuric acid or sulfate solutions than pure lead or other lead alloys. The uniformly dispersed copper particles give rise to local cells in which lead forms the anode and copper forms the cathode. Through this anodic corrosion of the lead, an insoluble film of lead sulfate forms on the surface of the lead, passivating it and preventing further corrosion. The film, if damaged, rapidly reforms. 

Volatilization. In this simplest separation process, the impurity or the base metal is removed as a gas. Lead containing small amounts of zinc is refined by batch vacuum distillation of the zinc. Most of the zinc produced by smelting processes contains lead and cadmium. Cmde zinc is refined by a two-step fractional distillation. In the first column, zinc and cadmium are volatilized from the lead residue, and in the second column cadmium is removed from the zinc (see Zinc and zinc alloys). 

Commercial-grade nitroparaftins are shipped and stored ia ordinary carbon steel. However, wet nitroparaftins containing more than 0.1—0.2% water may become discolored when stored ia steel for long periods, even though corrosion is not excessive. Aluminum and stainless steel are completely resistant to corrosion by wet nitroparaftins. Storage ia contact with lead (qv), copper, or alloys containing these metals should be avoided. Polymeric materials for gaskets, hoses, and connections should be tested for thek suitabiHty before exposure to nitroparaftins. 

Antimony Alloys. Approximately one-half of the total antimony demand is for metal used in antimony alloys. Antimonial lead is a term used to describe lead alloys containing antimony in proportions of up to 25%. Most commercial lead—antimony alloys have antimony contents less than 11%. The compositions of several important antimony alloys are given in Table 4. 

This bismuth—calcium—magnesium dross also contains lead that must be removed. The dross is heated in a ketde to free any entrapped lead that melts and forms a pool under the dross. This lead is cast and returned to the bismuth separation cycle. The dross is then melted and treated with chlorine and/or lead chloride to remove the calcium and magnesium. The resulting molten metal is an alloy of bismuth and lead, high in bismuth which is then treated to produce refined bismuth metal. 

Lead alloys containing small amounts of calcium aie formed by plunging a basket containing a 77 or 75% calcium—23—25% A1 alloy into a molten lead bath or by stirring the Ca—A1 alloy into a vortex created by a mixing impeUor (19). 

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