Nondestructive testing of thermal shock resistance of cordierite/silicon carbide composite materials after cyclic thermal shock

Abstract

Two different types cordierite/silicon carbide composite ceramic materials (KS 50 and KZ 50) were used for this investigation. Both materials were exposed to the water quench test from 950 degrees C, applying various numbers of thermal cycles. When refractory samples are subjected to the rapid temperature changes crack nucleation and propagation occurs resulting in loss of strength and materials degradation. The formation of cracks decreases the density and elastic properties of material. Therefore, measuring these properties can directly monitor the development of thermal shock damage level. Dynamic Young modulus of elasticity and strength degradation were calculated using measured values of ultrasonic velocities obtained by ultrasonic measurements. Level of degradation of the samples was monitored before and during testing using Image Pro Plus program for image analysis. The capability of ultrasonic velocity technique and image analysis for simple and reliable nondestructive methods of characterization was presented in this investigation. It was found that both composite materials exhibit good thermal shock resistance.