Copper reinforced SiAlON matrix composites produced by spark plasma sintering

Abstract

Cu particles (vol%. 0, 10, 20, 30) were incorporated into the αı:βı-SiAlON matrix to investigate its effect on fracture toughness, Vickers hardness, density, friction, and wear. The composite powders were prepared by planetary milling and sintering was carried out by spark plasma sintering at a temperature of 1600 °C for 10 min. The bulk density of Cu- αı:βı-SiAlON hybrid composites varied between 3,2501 and 2,9547 g/cm3, % open porosity values of composites increased with the addition of Cu. The fracture toughness showed improvement when the content of copper is 30 vol% (8,76 MPam1/2). On the other hand, hardness decreased from 17.6 GPa to 12.25 GPa, as expected, related to copper's low hardness value compared to the SiAlON matrix. Although the copper phase remained stable after sintering, it was determined that some of it formed copper silicide phase. In terms of wear, the use of metallic second phase as copper seems to enormous addition for SiAlONs in order to develop wear properties depending on the provided physico-mechanical properties such as high fracture toughness, self-lubrication etc., which discussed in this study. The wear rates were decimated in SiAlON matrix with the 30 wt% the optimal amount of copper.