Erosion behavior of TiC and Cu-TiC contact materials under vacuum arc

Abstract

TiC compact and Cu-TiC composites were fabricated by Spark Plasma Sintering and their arc erosion behavior in vacuum was investigated in detail. It was found that TiC cathode becomes brittle and cracks easily during the arc erosion process, and TiC particles in Cu-TiC cathodes also exhibit similar behavior. After the first vacuum breakdown, erosion pits are mostly concentrated on the TiC particles at Cu-TiC cathode. After the repeated vacuum breakdowns, TiC particles are more easily eroded than the Cu matrix. In the arc-eroded zone, TiC particles are melted before Cu. Thermal cracks are developed not only inside the TiC particles but also at the interface of Cu and TiC. Both Ti and C can be found as the decomposition products of TiC under vacuum arc erosion. The obtained results suggest that a moderate amount of TiC addition (less than 5 %) can effectively disperse the arc and protect the Cu matrix from arc erosion. An excessive TiC addition is harmful since TiC has the possibility to be broken into small fragments and suffers severe ablation under cathodic arcs.