Young’s modulus measurements of magnesia–spinel composites using load–deflection curves, sonic modulus, strain gauges and Rayleigh waves

Abstract

Abstract The extent of interlinking of the microcracking and a decrease in strength and modulus values were determined to be a function of both spinel particle size and volume fraction to allow calculation of thermal shock parameter, R‴. Measurements of Young’s modulus were carried out both at room temperature and after thermal shock testing by using the load–deflection curves (defined as “mechanical” modulus) and by the sonic modulus technique. The values obtained from these methods were significantly different for quenched/unquenched samples. To understand the basis for these differences, strain gauge and Rayleigh wave methods were also used to determine Young’s modulus of the composites. Modulus values obtained from these methods confirmed the differences measured, and provided a guide to the values to be used in calculating thermal shock parameters. The mechanical modulus technique was considered the most meaningful indicator of Young’s modulus for a situation in which large mechanical strains were to be applied to the materials during thermal shock.