Water-Quench Thermal Shock Testing for Ceramic Disks

Thermal shock fracture testing was performed on both alumina and silicon nitride by water-quenching method. Disk-shaped specimens in this study were preferred because of their easier processing and smaller volume as composed to the pencil-shaped specimen recommended by JIS. Thermal stress in the specimen during quenching was calculated by numerical analysis in order to evaluate the critical temperature difference, Δθc. The heat transfer coefficient of water was previously measured on a Ni-specimen under experimental conditions similar to the present thermal shock test. Observed values of Δθc agreed well with the calculated values for alumina, but disagreed by about 150K in silicon nitride.