Different types of electrical contacts and alloying process

It is difficult for a single pure metal to meet all the requirements of the electrical contact. With the development of vacuum switch gear to large capacity, electrical contact materials have experienced the development process from single metal to binary and then to multicomponent composites. In different application occasions, the requirements for contact materials also have different degrees of emphasis. There are many contradictions between the electrical characteristics of contacts and the physical properties of materials;

1. Low cut-off level electrical contact requires the material to have low conductivity, thermal conductivity and low melting point. The high breaking capacity, fusion welding resistance and electric wear resistance require the opposite properties. This is also one of the biggest difficulties in developing contact materials.

2. electrical contact Materials with fusion welding resistance are generally brittle and have poor strength, which is in contradiction with the requirements for higher mechanical strength, deformation resistance and electrical wear resistance of contacts. In order to solve or reduce the above contradiction, most material workers believe that alloying is the only choice. In the selection of alloy elements, the following trends exist according to different requirements.