In order to avoid the burning of the silver contact, the end of the static contact is made into a curved shape, and the middle part of the moving contact protrudes. This way the arc will not burn on the contact surface. It is a better form of contact and its use is increasingly widespread. The above discussion about  the working process of the contacts places many demands on the material. Because copper has good electrical and thermal conductivity. Have enough hardness. Higher melting point, easy to process. Therefore, it is widely used as the conductive part of the contact of the high voltage circuit breaker. However, copper is easily oxidized by hand, and the contact resistance is large after oxidation. Therefore, in some circuit breakers, the silver layer is covered outside the copper main contacts. Silver has good electrical conductivity. Its oxide film is also electrically conductive. After silver plating, it can improve the working performance of copper contacts. With the frequent use of the circuit breaker, the arc heat effect on the silver contact is significantly increased, and the contact surface may be seriously worn, so the heat resistance, the arc resistance and the wear resistance of the silver contact are put forward higher requirements. The powder rice metallurgy method has opened up a new way for the development of contact materials. Powder metallurgy does not use ordinary metallurgy methods, but mixes the powders of the two metals together in a mold for press molding. It is then sintered in a protective gas (hydrogen). This type of gold is actually a mixture of institutions. Because of its similarity to ceramics, it is also called the alloy. Copper-tungsten, silver-nickel and silver should be widely used in high-voltage circuit breakers. Graphite as an arc-resistant head or arc-resistant ring on the contact. Used in relays, contactors, air switches, current limiting switches, motor protectors, micro switches, instrumentation, household appliances, automotive electrical appliances (light switches, starter motors and other load switches), leakage protection switches. Compared with silver cadmium oxide, silver tin oxide does not contain toxic metal cadmium. The metal oxide has high thermal stability, good electrical and thermal conductivity, high heat resistance, arc erosion resistance and anti-melting during the on-off process. Weldability, thus ensuring the reliability of electrical operation and increasing the service life. Silver tin oxide develops rapidly. Even in some electrical switches, silver tin oxide can be used directly instead of silver cadmium oxide. The use range is from 10A to 100A, which is close to or even better than silver cadmium oxide in many properties. In order to avoid contact burning, the end of the static contact is made into a curved shape, and the middle part of the moving contact protrudes. This way the arc will not burn on the contact surface. It is a better form of contact and its use is increasingly widespread. The above discussion of the working process of the contacts places many demands on the material. Because copper has good electrical and thermal conductivity. Have enough hardness. Higher melting point, easy to process. Therefore, it is widely used as the conductive part of the contact of the high voltage circuit breaker. However, copper is easily oxidized by hand, and the contact resistance is large after oxidation. Therefore, in some circuit breakers, the silver layer is covered outside the copper main contacts. Silver has good electrical conductivity. Its oxide film is also electrically conductive. After silver plating, it can improve the working performance of copper contacts. With the frequent use of the circuit breaker, the arc heat effect on the contact is significantly increased, and the contact surface may be seriously worn, so that the heat resistance, the arc resistance and the wear resistance of the silver contact are put forward higher requirements. The powder rice metallurgy method has gotten a new way for the development of contact materials.