Tungsten Copper Used for Vacuum High-voltage Switch

Tungsten copper composite materials have widely used in electrical contacts, high voltage switches and breakers, especially in high voltage SF6, air / oil medium, large current circuit breaker. Recent years, with the rapid development of vacuum high-voltage switch, the contact materials have some innovation correspondly. Compared with other contacts, vacuum contact materials have higher requirements. Except the normal properties of switches, due to the surface of contact is particular clean, which will be easier welded in the air. So based on high resistance to weld, it also needs higher welding resistance, higher anti-electric erosion, low cut-off current and low content of gas. And tungsten copper excellent properties can perfectly meet the needs of high-voltage switch contacts.

From compression molding, for tungsten copper sheet contacts, CIP (Cold Isostatic Pressing) has good forming performance, but it has higher equipment investment and lower material utilization. The mechanical molding should be noted that the gap of molding tools and tungsten powder granularity. The smaller gap will cause the difficulties in stripping; the larger gap will make tungsten powder scratch the mold and produce the cracks on the surface of compact. From sintering process, porous tungsten skeleton sintered is the key process of tungsten copper manufacturing. High-temperature sintering is easy to remove impurities and ensure the electrical conductivity and the gas content meet the requirements. In addition, during the sintering process also need to consider the tungsten powder particle size, size distribution and pressing density. Too low temperature will increase the porosity and reduce the density and hardness of products; too high temperature will reduce the content of Cu and the electrical conductivity decrease. Overall, choose pure tungsten powder as raw material, mechanical molding, sintering furnace hydrogen reduction, hydrogen protection copper infiltration process to produce high-pressure vacuum switch tungsten copper material, it has high strength of porous W skeleton, low gas content, Cu has network-like distribution, tungsten copper matrix bonded tightly.