Electric Erosive Resistance of Tungsten Copper Electrode Improving

Tungsten copper material is a kind of composite material that composed of tungsten and copper, which not only has high hardness and high density, but also has excellent electrical and thermal conductivity, electric erosive resistance and welding resistance. It is the best choice in electrode and contact materials, especially in EDM (electrical discharge machining), ECM (Electrochemical Machining), circuit breaker, vacuum contact and high voltage switch has an extensive application prospect. Generally, the comprehensive property of tungsten copper is determined by the proportion of tungsten and copper.

On one hand, tungsten (W) has high density, high hardness, high strength and good chemical stability, the hardness of tungsten copper electrode will remarkably increase with the increasing amount of tungsten, especially the tensile strength at high temperature. It can practically embody that the wastage of tungsten copper electrode is lower and the stability of machining is improved. On the other hand, owing to the increasing amount of tungsten, the content of Cu will decrease, which weakens the thermal and electrical conductivity of tungsten copper electrode. On the contrary, the less tungsten that is the content of Cu becomes a majority, the plasticity, thermal and electrical conductivity, sweat cooling and thermal shock resistance of tungsten copper electrode will be correspondingly improved.

In addition, there is a big difference between the melting point of tungsten and copper (W-3410℃, Cu-1084.5℃). It belongs to completely mutual insolubility system and only infiltrates with each other at high temperature so that it is not suitable for common casting process and requires powder metallurgy (PM) with copper infiltration (Tungsten skeleton infiltrated by copper liquid and the pores filled with copper at the high temperature higher than the melting point of copper).

Recent years, more and more tungsten copper electrode manufacturing processes are appearing, which improve the traditional process to strengthen some properties and push forward the better applications of tungsten copper electrode according to the different emphasizes of electrode (such as intercepting level, electric erosive resistance, welding resistance and so on). This paper concentrates on two kinds of process: one is research in nano tungsten copper fabricating, which produces nano grains through improving the porosity of tungsten skeleton infiltrated; another one is based on the traditional powder metallurgy (PM), add rare earth or rare earth oxide grain before copper infiltration. Both of two kinds of process have some advantages and disadvantages.

• < Prev
• Next >