EDM mechanism of single crystal SiC with respect to thermal, mechanical and chemical aspects

In this study, electrical discharge machining (EDM), a non-contact thermal machining process, is proposed for machining single crystal silicon carbide (SiC) which exhibits extreme mechanical hardness. However, as a semiconductor, SiC demonstrates significantly different EDM characteristics compared with those of metallic materials. This research clarifies the EDM characteristics of SiC from thermal, mechanical and chemical aspects through experimental and analytical approaches. The heat transfer analysis of a single discharge of SiC taking into account Joule heating effect revealed that Joule heating effect can increase the surface temperature of SiC near the discharge spot considerably. On the other hand, experimental investigations on the EDM of SiC found that brittle fractures along crystal orientations occur in the EDM of SiC due to thermal shock. However, the influence of the crystal anisotropy of SiC on the EDM characteristics was not significant. Finally, the EDM mechanism of SiC was investigated from chemical aspects. Oxidation reaction was confirmed in the EDM of SiC in deionized water. All of these factors helped improve the machining rate of SiC to a certain extent.