Tungsten Electrode Production Technology-Sintering Process and Influence Factors

Tungsten powder and rare earth oxide powder after pressing, tungsten blanks’ density and strength have been greatly improved. After pressing, the blanks should to process sintering. The sintering process will affect tungsten blank’s density, grain size, distribution of rare earth oxides and high temperature evaporation loss quantity and so on, thereby affecting the performance of the tungsten electrode. In the sintering process, time, temperature, heating gradient, heating rate and purity are the main factors affecting the properties of sintered blanks.

When the powder particles is small, if the sintering temperature is too high, the tungsten grain will grow dramatically and will reduce the matrix diffusion coefficient of rare earth oxides in tungsten matrix, increasing electrode’s fare damage rate. Besides, high sintering temperature will lead to low-melting material aggregation, increasing segregation and rare earth oxides loss, so rare earth oxides distributed in the tungsten matrix is unevenly. Meanwhile, the sintering temperature is too high is prone to produce anti-sintering phenomenon, so that tungsten blanks density will decline. Because during the multi-component series sintering, the densification is based on diffusion, with the sintering temperature increase, the diffusion coefficient increases as well, and the shrinkage of sintered blanks become slow. When the sintering temperature is too low, the sintered density of the tungsten electrode can reach requirement also affect the using results.

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