Determination of thermal shock resistance of silicon carbide/cordierite composite material using nondestructive test methods

Abstract

In the present work Mg-exchanged zeolit and silicon carbide were used as starting materials for obtaining cordierite/SiC composite ceramics with weight ratio 30:70 and 50:50. Behavior of composite ceramics after thermal shock treatments was investigated. Thermal shock of the samples was measured using standard laboratory procedure, water quench test (JUS.B.D8.319.). Level of surface deterioration before and during quenching was monitored by image analysis. Ultrasonic measurements were used as nondestructive quantification of thermal shock damage in refractory specimens. 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 are presented in this investigation. It was found that both composite materials exhibit good thermal shock resistance.