Effect of cooling configuration on thermal shock fracture toughness of SiC

Abstract

Experiments were carried out to establish a test method for thermal shock fracture toughness and to generate the experimental data for silicon carbide. A 20mm wide, 50 mm long, and 6 mm thick specimen having an edge crack in the central section was heated up to a given temperature and quenched in such a way that the crack mouth side of the specimen was sunk to a depth of 1 mm from the water surface. The thermal shock fracture toughness of SiC was greater than the fracture toughness obtained using a three-point bending specimen at the corresponding temperature. This was well explained from the fact that the normal stress component parallel to the crack line is greater than the perpendicular stress component near the crack tip in the thermal shock specimen. Time histories of the stress intensity factors for various values of a/W and two cooling methods were analysed by using the finite element method and appropriate conditions were determined.