Determination of thermal shock resistance in refractory materials by ultrasonic pulse velocity measurement

Thermal shock resistance of refractory materials is one of the most important parameters in refractory material characterization since it determines their performance in many applications. Ultrasonic pulse velocity testing was used for non-destructive quantification of thermal shock damage in refractory plates used as support for the firing of porcelain articles. When refractory materials are subjected to the industrial thermal cycles crack nucleation and propagation occurs resulting in loss of strength and material degradation. The formation of cracks decreases the velocity of ultrasonic pulses travelling in the refractory because it depends on the density and elastic properties of the material. Therefore measuring either of these properties can directly monitor the development of thermal shock damage level. Youngʹs modulus of representative samples was calculated using measured values of ultrasonic velocities obtained by ultrasonic pulse velocity technique. Results were compared with industrial statistical data of thermal shock behaviour of the investigated materials. The capability of the ultrasonic velocity technique for simple, sensitive, and reliable non-destructive characterisation of thermal shock damage was demonstrated in this investigation.