Influence of Ti3SiC2 content on erosion behavior of Cu–Ti3SiC2 cathode under vacuum arc

Abstract

In this study, a series of Cu–Ti3SiC2 composites with different Ti3SiC2 contents were prepared by spark plasma sintering. Their mechanical properties and electrical resistivity were investigated. Through analyzing the morphology and composition of the eroded regions, the effect of Ti3SiC2 content on the erosion behavior of Cu–Ti3SiC2 cathodes under vacuum arc was studied. Results show that the relative density and bending strength of the Cu–Ti3SiC2 composites decrease with the increasing Ti3SiC2 content, while the opposite holds for hardness and electrical resistivity. The morphology and phase composition of the erosion zone is dominated by the decomposition process and the amount of Ti3SiC2 in the cathode. Cu–Ti3SiC2 cathodes containing 10 mass%Ti3SiC2 or less displayed relatively flat eroded surface morphology. Cathodes with high Ti3SiC2 content suffered more serious erosion with voids, cracks, and severe decomposition of Ti3SiC2, all of which contribute to impairing the arc ablation resistance of the composite. Ti3SiC2 particles decomposed into TiC and Si vapor; eventually, this TiC also decomposed into Ti vapor and C, leaving a considerable amount of C on the arc affected cathode surface. Excess addition of Ti3SiC2 particles not only deteriorates the strength but also the electrical and thermal conductivity of the composite, both of which in turn harms the arc erosion resistance of the material. These results suggest that the optimal Ti3SiC2 content is below 10 mass% in the composite.