Tungsten Powder Granularity Effect on Tungsten copper electrode

Since the high strength, excellent thermal and electrical conductivity and arc erosion resistance, tungsten copper has been becoming the one of the important materials for electrode application. There are many influencing factors of tungsten copper electrode materials, but the vast majority of literature can consult to affect mostly concentrated in the preparation process (tungsten skeleton, density, hardness, uniformity) of tungsten copper electrode material. We introduce the effect of tungsten powder granularity on tungsten copper electrode. Viewed from the distribution and structure, tungsten copper with the same composition, the finer particle size of tungsten will distribute more uniformly. But the possibility of closed-pore and defects appearing is also increasing, Cu enrichment increasing and the overall uniformity decreasing.

For the aspect of the hardness and the density, with the increasing of powder granularity, the pressing density and degreasing density of the tungsten skeleton fabricated by different granularity of tungsten powder is basically the same, and the overall density of tungsten copper also decreased after the infiltration. Take tungsten copper W-30Cu as example, When the tungsten powder particle size of 2.65μm, the highest hardness, Brinell hardness up to 222HB. With the powder size increases, the hardness decreases when the tungsten powder particle size of 8μm minimum hardness, Brinell hardness is 190HB. This is due to the higher density brings the greater brittleness. The powder granularity decreases, the specific surface area increases, the higher surface energy, the greater sintering activity and the more obvious volume shrinkage after sintering, which increases the content of W, improves the overall density and hardness. In the electrical conductivity, tungsten powder particle size of the smaller and more easily when pressed cause tissue inhomogeneity of skeleton sintered in the passage is closed and prone to clogging, thus resulting in voids or defects in copper-rich material and cause copper deficiency or liquid infiltration feeding can not effectively reduce the integrity of the copper network grid after infiltration, so that the electrical conductivity decreased.