TENSILE BEHAVIOUR AND DAMAGE EVOLUTION OF A C/SiC MINICOMPOSITE FABRICATED BY CHEMICAL VAPOUR INFILTRATION

摘要

The tensile behaviour of a C/SiC minicomposite fabricated by chemical vapour infiltration was examined and the associated damage evolution was monitored by using acoustic emission (AE) technique. The microstructure of minicomposite can be characterized by a uniformly thick SiC sheath, the thin fibre coatings, and large pores due to the tendency of fibres to cluster in the minicomposite. The load-displacement curves of minicomposite show a greatly nonlinear behaviour with four distinct regimes: initial self-alignment due to relaxation of fibres followed by preexisting microcrack extension, matrix macrocrack multiplication and then saturation. All these regimes can be well characterized by the corresponding AE activities. Therefore, it is believed that such experimental results would be beneficial to the optimization of processing conditions and derivation of parameters necessary for further modelling of the thermomechanical behaviours of real C/SiC composites with more complex architectures by fabricating minicomposites in a short time.