High Density Rare Earth Tungsten Electrode Manufacturing

As an indispensable functional material in machinery, shipbuilding, aerospace, construction, nuclear power, metallurgy and other industries, tungsten electrode materials are mainly used in inert gas shielded welding, plasma cutting, spraying and smelting technology. At the same time, another important application of tungsten electrode material is to act as a hot cathode electron emission source in welding process.

Recently, some researchers have developed a preparation method of rare earth tungsten electrode material. This method adopts ball milling, hot pressing, electron beam vacuum high temperature melting and heat treatment, and finally obtains the rare earth tungsten electrode material with high density and good plasticity.

Step 1 the tungsten powder with average particle size of 1 micron and purity of 99.2% was mixed with zirconia powder with average particle size of 4 micron and purity of 99.3%. After milling for 1 hour, the zirconia powder takes up 1% of the total mass of the mixed powder.

Step 2 hot-pressing: the tungsten-based zirconia bulk mixture is obtained by hot-pressing the mixed powder at 1800 ℃ and 30 MPa for 1 h.

Step 3 electron beam melting: Put the tungsten-zirconia bulk mixture in the crucible of the electron beam melting furnace, vacuum it below 0.0042Pa, open the electron gun at high pressure of 30 kV, beam current of 600 mA for smelting, smelting for 20 minutes, turn the tungsten-zirconia alloy ingot upside down after solidification and cooling, smelting at high pressure of 30 kV and beam current of 400 mA for 20 minutes. The tungsten zirconia alloy ingot was obtained after solidification and cooling.

Step 4 vacuum heat treatment: vacuum heat treatment has no oxidation, no decarbonization, no element dilution characteristics, can achieve bright heat treatment, can make the parts degrease, degassing, avoid surface pollution and hydrogen embrittlement; at the same time can achieve control heating and cooling, reduce heat treatment deformation, improve material performance;

Rare earth elements can not only increase the recrystallization temperature, but also activate electron emission. The W-RE alloy formed by combining with tungsten has the characteristics of low work function, high melting point and low vapor pressure. It is a kind of electrode material with high performance and safety.

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