Abstract
Bending strengths of porous Al2O3 ceramics with relative densities of 97, 74 and 60-65% were measured before and after the thermal shock by water quenching. An instantaneous decrease in strength was observed when the ceramics with relative densities of 97 and 74% were thermally shocked through the temperature difference of larger than 200°C. On the other hand, the strength of the ceramics with relative densities of 60-65% did not show the instantaneous decrease, but gradually decreased with an increase in quenching temperature. The width of the cracks caused by the thermal stress fracture was 2-3μm when the temperature difference in quenching was 585°C. Thermal shock fracture resistance parameter (R′) and thermal shock damage resistance parameter (R″) were calculated for each ceramics, which resulted that the high density ceramics showed higherest R′ and the lowest R″ values.
