Comparative mechanical evaluation of two 2,5D C/SiC composites processed via chemical vapor infiltration and powder infiltration/polymer injection routes

Ceramic matrix composites were processed using two matrix infiltration techniques: chemical vapor infiltration (CVI) and powder infiltration/polymer injection. However, the two composites were elaborated from an identical fiber preform, and with a similar pyrocarbon interphase deposited onto the fibers by CVI. They reached comparable densification level and had an equivalent monotonic tensile behavior, although the CVI technique gave a higher modulus and a 10% higher tensile strength. The main differences were found in the details of the mechanical behavior (Young`s modulus evolution, residual strain and unloading-loading loops) and in some fatigue behaviors. These differences were related to the matrix modulus and microstructure. Merits of the resulting composites and the two techniques were discussed.