Micro-electrical discharge machining characteristics of newly developed conductive SiC ceramic

An electrically conductive SiC ceramic was fabricated via hot-pressing a 72.6 wt% β-SiC, 7.6 wt% polysiloxane, 4.3 wt% phenol resin, and 15.5 wt% yttrium nitrate powder mixture. It was machined into 300-μm-thick cylindrical specimens (YN-SiC) with diameters of 3 mm. The micro-electrical discharge machining characteristics such as the number of shorts, machining time, entrance clearance, material removal rate (MRR), and debris size of the conductive SiC ceramic were compared to those of SUS304. The number of shorts for SiC was smaller than that of SUS304 because of its low electrical conductivity. As the unit discharge energy increased, the debris size and its standard deviation for YN-SiC increased, while those of SUS304 decreased. The machining time for the SiC was longer than that of SUS304 because of the increase in the number of shorts at a small discharge energy. It was also found that the entrance clearance of the SiC was the smallest at a unit discharge energy of about 7 μJ. The MRR was inversely proportional to the machining time.