Assessment of the intrinsic damage to refractory materials at high temperatures using the laser ultrasonic pulse method

Abstract

Refractory materials play a significant role for high temperature industrial processes. In such harsh environments occurring material damages are a challenge and their assessment is important. In this work refractory material damages have been assessed by laser ultrasonic pulse (LUP) method by investigating changes of Young's modulus and Poisson's ratio up to 1000 °C. The LUP method operates by laser ultrasonic wave generation and detection and is therefore non-contacting and non-destructive. As a consequence of material damages, the propagation velocities of the ultrasonic waves inside the materials are affected. Therefore, the elastic properties change and material damages can be determined up to a microstructural range. A broad variety of refractory ceramics were examined e.g., fused silica, alumina, andalusite and high alumina composite materials. After induced intrinsic damages by pressing and water quenching thermal shocks from 950 °C to 10 °C Young's modulus and Poisson's ratio decreased.