Fracture behaviour of cross-ply Nicalon/CAS-II glass-ceramic matrix composite laminate at room and elevated temperatures

The fracture behaviour of cross-ply Nicalon/CAS-II glass-ceramic matrix composite laminate has been investigated as a function of temperature, loading rate and environment. Tests were carried out at 20, 600, 800, 1000 degreesC in air and also at 1000 degreesC in vacuum. Increased flexural strength was obtained with increased loading rate but it decreased with increasing test temperature. Although the change in flexural strength was not very significant for the loading rates (10(-3) and 10(-1) nm/min) employed in this study except at 600 degreesC in air, the influence of environment was dramatic. The flexural strength at 1000 degreesC in vacuum was comparable to the value obtained at room temperature in air, however, the flexural strength at 1000 degreesC in air reduced significantly from its room temperature value. Two major damage modes have been identified: fibrous at room temperature and non-fibrous at high temperature. (C) 2002 Elsevier Science Ltd. All rights reserved.