Early contact materials with pure tungsten, pure aluminum and pure copper and silver, precious metals vacuum switch almost all use the refractory metals such as W, Mo, as contact material, this kind of contact material with a series of advantages, such as there is proper breaking capacity, good compressive strength and resistance to welding the appropriate heat transfer coefficient and the conductivity, the arc ablation rate is small, and contact the service life is long, etc., until now has been widely used in vacuum switch breaking small current. But high melting point of pure metal contact material has many shortcomings, such as breaking current and high level of river closure, limiting the use of vacuum switch. Started developing composite after contact, the present study is more low voltage electrical appliances silver based contact materials, double layer or multilayer compound contact materials, vacuum switch, high voltage and other closed switch with contact materials.
Foreign study of electrical contact element and material has a history of 78. At present foreign production and research and development of electrical contact materials company mainly AMI DODUCO (Germany), forthcoming OMC hair company (USA) Metalor company (glass), etc.In our country since 1956 in contact materials research and production, after nearly 50 years of development, the current domestic engaged in electrical contact materials production enterprises for more than 60 (means only members of the wga's electrical alloy), total about 12000 employees, assets of about 1.2 billion yuan, in more than 60 branch members, mostly private enterprises (about 90%), about 10 enterprises with certain scale and technical strength, the product variety, technical personnel and production equipment is complete, in terms of the varieties and properties of contact materials, The current international domestic all can produce the electric contact material variety, in general, can satisfy the demand of the electric switch,
The species is close to or reached the international advanced level. But the scale of production, technological level, product quality and so on, compared with the developed countries contact materials in our country is still there is a big gap. Mainly displays in: (1), enterprise scale is small, low degree of automation, product quality is often unstable. (2) materials in the form of contacts, wire, sheet, the terminal product supply added value is small. (3) the demand for raw materials and control measure and post-treatment of the product. (4) pay attention to production, ignore scientific research
