Young's modulus, thermal expansion coefficient and fracture behavior of selected Si-B-C based carbides in the 20-1200 °C temperature range as derived from the behavior of carbon fiber reinforced microcomposites

The Young's modulus, thermal expansion coefficient and fracture behavior of different ceramic phases in the Si-B-C system have been determined from room temperature up to 1200 degrees C using results of tests performed on matrix-dominated carbon fiber reinforced microcomposites by means of a specific high temperature testing apparatus. Results have shown that the boron-rich materials had higher stresses to failure and thermal expansion coefficients than silicon-rich materials whereas all the boron containing materials exhibited a viscoplastic time-dependant mechanical behavior over 1000 degrees C. The thermoelastic values of the Si-B-C based carbides thus obtained have been used to compute thermal residual stresses in model composite systems, in view of understanding some results reported in the literature regarding the implantation of layered matrices in ceramic matrix composites. (c) 2007 Elsevier Ltd. All rights reserved.