Thermal shock fracture behavior of alumina ceramics containing pores

Thermal shock fracture behavior of alumina ceramics containing pores was studied by measuring strength after water-quenching. The thermal shock fracture behavior was evaluated by a critical temperature difference (DeltaT(c)) and a survival strength (sigma(r)) after water-quenching test. The critical temperature difference increased with increasing porosity. On the other hand, an influence of pore size could not be recognized. From the comparison between measured and estimated values, it was suggested that an increase in critical temperature difference was originated from the adiabatic effect by air bubbles generating at surface pores. The survival strength after water-quenching test increased with increasing pore size, but increase became smaller in pore sizes over 10 mum. The reciprocal of squared survival strength could be related with the elastic strain energy stored up to fracture.