Fabrication and Design of Silicon Carbide Whisker Reinforced Mullite Composites.Topical Report, September 1, 1986-November 30, 1989

摘要

The laminates were designed to improve the thermo-mechanical behavior for hightemperature applications, based upon the measured properties of individual laminas and the laminate plate theory. Otpimized laminate design, with minimum core residual tensile stress and sufficiently deep surface-layer of residual compressive stress, yielded a large improvement in fracture strength. The elastic properties and residual stresses of the designed laminates were evaluated experimentally and compared with those predicted using the laminate plate theory. The measured residual stresses in the laminates agreed well with the predicted values. Thermal shock resistance in mullite, monolithic composite laminate and optimized composite laminates was evaluated by water quenching samples to produce temperature differences ranging from 100 to 1100 deg C. The thermal shock resistance was determined from the change in Young's modulus and fracture strength. Based on the measure properties, the thermal shock initiation resistance parameter (R) was calculated and compared with the value observed experimentally. Finite element methods were used to predict the effectiveness of the optimized composite laminates to increase fracture strength and thermal shock resistance over monolithic mullite.