Alloys and soldering

Uses. Photographic materials electrical and electronics products alloys and solders in jewelry, mirrors, flatware, and coinage... 

Silver and its alloys and compounds have numerous applications. As a precious metal, silver is used in jewelry. Also, one of its alloys, sterling silver, containing 92.5 weight % silver and 7.5 weight % copper, is a jewelry item and is used in tableware and decorative pieces. The metal and its copper alloys are used in coins. Silver-copper brazing alloys and solders have many applications. They are used in automotive radiators, heat exchangers, electrical contacts, steam tubes, coins, and musical instruments. 

The total U.S. annual release of silver to land from production processes and consumptive uses in 1978 was estimated at 1.01 million kg (Scow et al. 1981). Of this amount, an estimated 630,000 kg were released from the photographic industry (in manufacture and developing), 165,000 kg from metals production, 150,000 kg from uses in electrical contacts and conductors, 60,000 kg from uses in brazing alloys and solders, and the remainder from miscellaneous uses. An additional 370,000 to... 

Negative health effects can result from corrosion of lead, corrosion of copper alloys and solder in water supply systems, and corrosion of copper plumbing in potable water systems. 

Because of its high thermal conductivity, diamond is an excellent heatsink material, mostly for hIgh-density electronic circuits. Athin slice, in size up to 3 X 3 X1 mm, is cut from a natural crystal, metallized by sputtering a gold alloy and soldered to a copper base. A typical diamond heat-sink configuration is shown in Fig. 12.12. ... 

Its alloys include solder, type metal, and various antifriction metals. Great quantities of lead, both as the metal and as the dioxide, are used in storage batteries. Much metal also goes into cable covering, plumbing, ammunition, and in the manufacture of lead tetraethyl. 

Alloys of tin are very important. Soft solder, type metal, fusible metal, pewter, bronze, bell metal. Babbitt metal. White metal, die casting alloy, and phosphor bronze are some of the... 

Although materials such as Portland cement (see Cement), solder (see Solder and brazing alloys), and siUcates can be considered to be adhesives, this discussion only includes organic materials such as those that form the materials presented in Table 1. 

Skiving is a variant in which the base metal surface oxides are mechanically removed foUowed immediately by pressure rolling of a precious metal or alloy strip. This is commonly used for inlays for electrical contacts and for jewelry fabrication. The common inlay materials include gold, silver, copper, brass, and solder. No heat is needed, and the coating is appHed only to designated areas so there is Htde waste (3,50). 

The atomic radius of silver (144 pm) is within about 15% of many elements, permitting sofid solutions with Al, Au, Be, Bi, Cu, Cd, Ge, In, Mn, Pb, Pd, Pt, Sb, Sn, Th, and Zn. These metals form useful braziag, jewelry, and soldering alloys. Copper is the only metal with which silver forms a simple eutectic between two sofid solutions (Pig. 3). Silver has extremely limited solubiUtyia B, C, Co, Cr, Pe, Ge, Ir, Ni, Mg, Mo, Se, Si, Te, Ti, and W. Thus these metals may be brazed by silver alloys without serious erosion during welding (qv). 

Molten tin wets and adheres readily to clean iron, steel, copper, and copper-base alloys, and the coating is bright. It provides protection against oxidation of the coated metal and aids in subsequent fabrication because it is ductile and solderable. Tin coatings can be appHed to most metals by electro deposition (see Electroplating). 

Gold, platinum, palladium, and silver are the principal components of most of the solders used for joining both noble and base metal alloys. Some solders for base metal alloys also contain nickel, chromium, and/or cobalt as primary ingredients. 

The contact between the aluminium layers and the ceramic substrate requires a joining material which will wet both metal and ceramic, and solders such as the conventional Pb-Sn alloy have been used which are molten during the annealing process. The contact between the solder and the aluminium layer is frequently unsatisfactoty because of the intervention of the AI2O3 layer, and a practical solution appears to be to place drree layers of metal clrromium in contact widr the aluminium, copper in contact with the clrromium, and gold between the copper layer and the solder. 

Major uses for (heso alloys are as while mcial bearing alloys, extruded cable slieatbiiig, and solders. Tin forms ihc basis of pewter used for uiliiian applications. 

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