Studying Thermal Shock Resistance of Ceramic Materials Based on Their Structural Sensitivity to a Stress Concentrator

Abstract

A method for determining the thermal shock resistance of ceramic materials is proposed based on their structural sensitivity to a stress concentrator controlling fracture during thermal loading. For this purpose, a prismatic sample with a specially created notch (stress concentrator) was subjected to thermal cycling realized by heating it to 850°C and cooling with a water jet (20°C). The coolant was supplied to the notch apex of the heated sample (local thermal shock (LTS) technique). By using the LTS technique, the thermal shock resistance of the following 3 types of ceramic materials was studied: α-Al2O3(type 1), α-Al2O3– β-SiC whiskers (20 vol.%) (type 2) and t-ZrO2 partially stabilized with Y2O3 (3.5 mol.%) (type 3). Type 2 ceramics has the highest thermal shock resistance, type 3 ceramics—the lowest, and type 1 ceramics occupies an intermediate position among the studied materials, which is associated with the specifics of formation and distribution of thermal defects in the structure of these ceramic materials as a result of using the LTS technique. The advantage of the latter consists in an explicit reproducibility of the results of determining thermal shock resistance (RT) within the studied batch of samples (measurement accuracy 3 – 5%).