Thermal shock of ground and polished alumina and Al2O3/SiC nanocomposites

The thermal shock behaviour of sintered alumina and alumina/SiC nanocomposites with 1, 2.5 and 5 vol.% SiC was studied. The thermal shock testing was carried out by means of quenching into water from high temperatures (ΔT in the range 0–750 °C). Both single shocks and repeated shocks were used. The damage introduced by thermal shock was characterised by degradation of strength in four-point bending and by changes in Young's modulus. The effects of the surface finish of the test specimens (either ground or highly polished surfaces) on the thermal shock resistance were also studied. In both alumina and nanocomposite materials, specimens with ground surfaces showed a better resistance to thermal shocks than specimens with polished surfaces. However, the resistance of the nanocomposite material to single and repeated thermal shocks was no better than that of the pure alumina.