Effect of Coating on Retention of SiC Particles in the Composite during Grinding

Abstract

The paper considers the problem of keeping coarse (150 µm) SiC particles in the composite when it is being ground with a cup diamond wheel with fine grains (20/14 µm). SiC particles were coated with Co, Ni, Cu, and WC and are denoted as SiC (Co), SiC (Ni), SiC (Cu), and SiC (WC), respectively. The powders were pressed in a steel mold with a diameter of 8.15 mm. Thecompacts were 5–8.5mm in height. The compacts were sintered in hydrogen at 980–1470 ºC and were hold for 1–2 h. In addition, samples consisting of SiC(WC) were impregnated with a WC +Ni eutectic melt (TN65). Metallographic analysis showed that in the samples consisting of SiC (Co), SiC (Ni), and SiC (Cu), SiC particles could not be retained in the grinding process due to the formation of brittle silicides during sintering. In case of SiC particles covered with WC, most of the SiC particles were not removed from the composite in the grinding process. When SiC(WC) samples were impregnated with the TN65 eutectic mixture, the SiC the particles mainly remained in place.