Evaluation of Thermal Shock Resistance of Ceramics : 1st Report, A Novel Quench Test Technique

Abstract

Under the prevailing quenching method by freely dropping specimens for a thermal shock test of high-strength ceramics, ambient gas is possibly introduced when the specimen is dropped into liquid, causing errors in the evaluation of retained strength and dispersements of measurement data. This paper clarifies that, by observation using a high-speed camera, the ambient gas is introduced when the specimen is dropped into liquid and is attached to the specimen while falling through the liquid, and proposes the dropping method and shape of the specimen which introduces the least ambient gas. Furthermore, it discusses the maximum dropping speed which does not introduce the ambient gas, as well as the influence of the properties of the liquid upon the introduction of the ambient gas. This paper also discusses the influence of the introduction of the ambient gas upon the cooling rate of specimens, and the quenching temperature difference which generates cracks.