Tungsten Copper High Voltage Contact Material

Tungsten copper based alloy is a pseudo-alloy composed of high melting point, high hardness tungsten and high conductivity and thermal conductivity copper. It has good arc erosion resistance, fusion resistance, high strength and high hardness. Contact materials for various types of ultra-high voltage, high voltage, medium voltage circuit breakers, transformer changeover switches, vacuum contactors, load switches.

At present, the main preparation methods of the contacts are a mixed-press sintering method, an infiltration method, and the like. The physical, electrical and mechanical properties of the materials prepared by the method of mixing-compression sintering are not ideal. In the preparation process of the infiltration sintering process, the liquid phase copper penetrates only by the capillary action of the pores of the tungsten or molybdenum skeleton, and the solidification phase of the copper is coarse and uneven. And high-temperature sintering causes the tungsten or molybdenum particles to aggregate and grow to form coarse and uneven structure.

In order to overcome the shortcomings of the above-mentioned technologies, some scholars have proposed a direct forming method for preparing W-Cu high-pressure contact materials. The technical scheme adopted includes the following steps:

The first step is to mix the raw material powders evenly according to the composition ratio of the high-pressure contacts, including 50-80% copper, 20-50% tungsten, 5-50 micron tungsten and 70-150 micron copper.

In the second step, the mixed raw material powder is input into the powder feeding system of the cold spraying system, and the heated gas is sprayed, the heated gas temperature is 500-550 ℃, and the raw material powder is under the action of 1.5-2.5 Mpa high pressure gas. The impact copper matrix is plastically deformed, and then deposited on the surface of the copper base to form a high-voltage contact material, and the gas is air.

In the third step, the W-Cu high-pressure contact material will be annealed at 1000-1100 ℃ for 20-30 minutes.

The above-mentioned method for preparing W-Cu high-pressure contact material simplifies the process, overcomes the high temperature deformation of copper base, finely and uniformly distributes copper solids, reduces the cost of cold spraying equipment, improves the safety of working process, is suitable for on-line processing, and saves the cost of spraying.

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