FLEXURAL BEHAVIOUR OF 2D SILICA -SILICA CONTINUOUS FIBRE-REINFORCED, CERAMIC-MATRIX COMPOSITES

摘要

Advanced materials, such as continuous fiber-reinforced ceramic-matrix composites offer significant enhancements in a variety of properties, as compared to their bulk, monolithic counterparts. These properties include primarily the flexural and compressive strength and fracture toughness / energy. However, till date, there are hardly any scientific studies that are reported in case of the silica based fiber reinforced advanced ceramic composites, which bring out the effects of various experimental conditions on these properties. Some of these experimental conditions become very important as they simulate nearly the service conditions of components that are made from these materials. In the present study, the effects of various test conditions on the flexural strength of 2D woven silica continuous fiber-reinforced, (silica) ceramic-matrix composite (CFCC) materials have been comprehensively evaluated and reported. These conditions include the span length (effectively the specimen dimensions), strain rate, test temperature, high temperature exposure and finally the thermal shock. The results obtained are discussed and rationalized in terms of the material characteristics and the mode of failure. The study reveals that the material exhibits a well defined critical span length (L_c), beyond which the mode of failure is tensile (fully bend or flexural loading) and also the fact that L_c depends on the strain rate and test temperature.