The Strength and Modulus of Imperfectly Bonded Whisker Reinforced Ceramic Matrix Composites

The whisker reinforced ceramic matrix composites show a significant improvement in room temperature strength and modulus over those of monolithic ceramics. However, at elevated temperatures, these materials do not exhibit any improve ment in the above mechanical properties. It is postulated that the degradation in modulus and strength with temperature occurs due to a deterioration of the whisker/matrix interface bond, that is, imperfect bonding. A micromechanics model was developed to explain this behavior and to predict the modulus and ultimate strength of whisker reinforced ceramic matrix composites at elevated temperatures. It was assumed that the interface was purely frictional in nature, and degradation in the mechanical properties was a result of the change in the bond strength and growth of preexisting interface imperfections. A paramet ric study was done to show the role of various micromechanical parameters on the ultimate strength and modulus of the composite.