Flexural strength and toughness of liquid phase sintered silicon carbide

Liquid phase sintering process of silicon carbide allows the obtaining of a dense sample at lower temperature than the solid state process with reduced grain growth and improved mechanical properties. In this paper mechanical properties at RT (room temperature) and at high temperature of liquid phase sintered silicon carbide (LPSSC) was determined. Flexural strength measurements were conducted by means of four-point bend tests in the range RT–1400°C. Hardness and fracture toughness were determined by Vickers indentation method at different load. Flexural strength changed from 532 MPa at RT to 240 MPa at 1400°C. SEM analysis showed that this behaviour is due to superficial oxidation of SiC and formation of yttrium silicate which create bubbles and cavities.