Thermal shock resistance of sintered alumina/silicon carbide nanocomposites evaluated by indentation techniques

The thermal shock resistance of sintered Al2O3/1, 2.5, and 5 vol% SiC nanocomposites was studied using two indentation techniques. In the first technique, "indentation thermal shock" measurements were made of the extension of median/radial cracks around Vickers indentations after quenching from various temperatures (up to 480degreesC) into a bath of boiling water. This technique allowed a critical thermal shock temperature, DeltaT(C)(Ind), to be quantitatively evaluated. In the second technique, "indentation fatigue" tests were conducted on the thermally shocked specimens; repeated indentations were made at the same site, and the number of load cycles needed to initiate lateral fracture was measured. The results showed that nanocomposites with an addition of SiC nanophase as low as I vol% had a thermal shock resistance superior to that of pure Al2O3.