Copper alloys applications

Copper is used extensively for its high thermal and electrical conductivity and corrosion resistance. In the United States, the most predominant of thousands of copper and copper alloy applications include building construction (largely sheet, tube, building wire, and hardware), 45 percent electrical and electronic products, 26 percent transportation equipment, 9 percent industrial machinery and equipment, 10 percent and consumer products, 10 percent, see also Electrochemistry. 

Application Data Sheet—Standard Designationsfor Wrought and Cast Copper and Copper Alloys, Copper Development Association, Greenwich, Conn., 1992. 

Nickel is usually alloyed with elements including copper, chromium, molybdenum and then for strengthening and to improve corrosion resistance for specific applications. Nickel-copper alloys (and copper-nickel alloys see Section 53.5.4) are widely used for handling water. Pumps and valve bodies for fresh water, seawater and mildly acidic alkaline conditions are made from cast Ni-30% Cu type alloys. The wrought material is used for shafts and stems. In seawater contaminated with sulfide, these alloys are subject to pitting and corrosion fatigue. Ammonia contamination creates corrosion problems as for commercially pure nickel. 

The choice of alloy for any particular application is determined by the desired physical, mechanical and metallurgical properties. Within these limits, however, a range of materials is usually available. It is essential that at the very earliest stage the choice of materials and the details of design of the installation should be considered from the point of view of corrosion, if the best performance is to be obtained in service. This is particularly true of copper alloys, where protective measures are not normally applied. 

Copper alloys in wrought or cast form are used for other purposes in ships and other marine installations, such as for propellers bearings, valves and pumps. One widespread application of aluminium-brass is its use for heating coils in tankers carrying crude oil or petroleum products. Some corrosion problems encountered in this and other applications on board ship have been described by Gilbert and Jenner . 

Much attention continues to be devoted to the corrosion behaviour of copper alloys in an increasing range of marine applications ... 

Standard Handbook — Copper, Brass, Bronze, Wrought Mill Products, 8lh edn, Copper Development Association Inc., New York (1985) Properties and Applications of Wrought Coppers and Copper Alloys , Meta Prog., 98, 85 (1970)... 

The periodic development and use of new steel alloys can improve ferrous corrosion resistance however, where economizer units are constructed of copper alloys, under certain conditions serious copper corrosion problems may result. This occurs when FW having a pH over 8.3 also contains small amounts of ammonia and dissolved oxygen (DO). The ammonia may be present, for example, as a result of the overuse or inappropriate application of certain amines. Further damage may occur from the plating-out of the copper-ammonia ion then created as a cathode on boiler tubes. This promotes anodic corrosion of the immediate surrounding anodic areas. 

In certain direct steam-contact process applications (such as in food and beverage processing or pharmaceutical preparations) the use of amine-based products in steam and condensate systems is subject to legal restrictions. Also, the use of ammonia or amines may be dependent on the materials of construction employed or technical limitations (such as the risk of copper alloy corrosion). 

This process is currently being used at five other installations manufacturing copper and copper-alloy products. The chemical rinse technique is applicable to electroplating operations and has gained... 

Researchers have tried to fabricate plates using many different metals— mainly, stainless steel, aluminum alloys, titanium alloys, nickel alloys, copper alloys, intermetallic alloys, and metal-based composites such as carbon fiber-reinforced aluminum alloys, carbon fiber reinforced copper alloys, etc. [26]. Although Ta, Hf, Nb, Zr, and Ti metals show good corrosion resistance and chemical stability [6], the cost of fhese metals is too high for them to be used as materials in metal plates. That is why relatively cheaper iron-based alloys, particularly stainless steel, have been popularly studied as plate material. In the following secfions, we will infroduce sfainless sfeel (SS) and SS plates, which have been extensively investigated and show promise for the final applications [6,11]. 

In electronic applications, where it is common to deposit copper and/or copper alloy and tin in sequence, with a nickel diffusion barrier layer, 0.5 fim thick, between the layers present, no failure occurs. Without the nickel layers between bronze/-copper/tin layers themselves, for instance, intermetaUic brittle layer(s) and Kirkendall voids are formed, leading eventually to separation of the coated system and substrate. 

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. 

One attractive property of beryllium is its nonsparking quality, which makes it useful in such diverse applications as the manufacture of dental appliances and of nuclear weapons. Beryllium-copper alloys find use as components of computers, in the encasement of the first stage of nuclear weapons, in devices that require hardening such as missile ceramic nose cones, and in the space shuttle heat shield tiles. Because of the use of beryllium in dental appliances, dentists and dental appliance makers are often exposed to beryllium dust in toxic concentrations. 

Tellurium—copper alloys are recommended for situations demanding a high production rate with no significant sacrifice in conductivity. These alloys can be soldered, brazed, or welded without incurring embrittlement. They are used in vacuum applications, forgings, screw-machine parts, welding-torch tips, transistor bases, semiconductor heat sinks, electrical connectors (qv), motor and switch parts, and nuts, bolts, and studs. Addition of tellurium significantly improves the surface of machined parts. 

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