Micro electrical discharge drilling characteristics of conductive SiC–Ti2CN composite

An electrically conductive SiC-Ti2CN composite was fabricated from β-SiC and TiN powders with 2 vol% equimolar Y2O3-Sc2O3 additives by conventional hot-pressing. The composite (electrical resistivity of nearly 10-4 Ω·cm) was wire electro discharge machined into a specimen having a thickness of 500 μm. Entrance clearance, machining time, number of shorts, material removal rate (MRR), counts, and the effects of the capacitance and voltage of conductive SiC-Ti2CN composite during micro electrical discharge drilling were measured and compared to those of SUS304. As the unit discharge energy increased, entrance clearance, machining time, and number of shorts decreased. A decrement in the number of shorts was the main reason for decrements in entrance clearance and machining time. MRR was proportional to unit discharge energy. The study to determine the location of shorts during electro discharge drilling was also conducted. It was founded that the short circuit occurred mainly at the beginning (0–1000 cts) because of low electrical density, and right before the exit (3000–5000 cts) owing to the difficulty of removing debris. Both the capacitance and voltage tended to be inversely proportional to the number of shorts.