Abstract
Thermal shock fracture behavior of KZr2(PO4)3 ceramic, which has a near-zero thermal expansion coefficient, was evaluated by the water-quenching test. The specimens having almost the same density, strength, Young's modulus, and thermal expansion coefficient, but different grain sizes, were prepared by adjusting the sintering conditions. The maximum temperature difference (ΔTmax), to which the specimens were subjected without failure in the thermal quench test, increased with decreasing grain size. KZr2(PO4)3 ceramic composed of fine grains<3μm withstood the test without lowering of strength even when quenching from 1300°C into water was repeated 20 times. The grain size dependence of ΔTmax has been attributed to residual stress caused by the thermal expansion anisotropy. As a result, grain size and thermal expansion anisotropy were incorporated into the equation for the thermal shock resistance.
