Experimental stress/strain behavior of SiC-matrix composites reinforced with Si–Ti–C–O fibers and estimation of matrix elastic modulus

NAL, Ube Industries Ltd and Shikibo Ltd have conducted a joint programme to develop and evaluate ceramic-matrix composites (CMCs) reinforced with Si–Ti–C-O (Tyranno®) fiber from Ube Ltd in an orthogonal 3-D fabric reinforcement configuration woven by Shikibo Ltd. For most of the composites, the polymer conversion (PC) technique was used for matrix consolidation, although chemical vapor infiltration (CVI) was also used for some composites. The polymer precursor processing route is considered to be more cost effective as compared to the conventional CVI route. These materials were characterized by excellent oxidation resistance compared to carbon/carbon composites. The room-temperature monotonic tensile strength exceeded 450MPa, and this was retained at 1200°C in vacuum. However, a micro-mechanical understanding of these composites has not been completed because the matrix properties were unknown. An attempt has been made to estimate the elastic modulus of these PC-based matrices in the initial purely elastic region and an estimated value range obtained. The model is based on a simple linkage of parallel and serial arrangements of elastic blocks.