Carbon fibre-reinforced CMCs by PCS infiltration

C/SiC-based composites were produced by infiltration of a woven carbon fabric preform with a polycarbosilane (PCS) solution. Progress of the infiltration process up to eight infiltrations was followed by density measurements, microscopy and mechanical testing. After six infiltration cycles, the density increase tended to a plateau. Dense deposition of the matrix on the outer surface sealed off the core of the composite, which hindered successive infiltrations. With further re-infiltration cycles, the development of the matrix and the degree of bonding between the fibre and matrix increased. There was also a transition in the failure mode of the composite, when tested in 3-point bending, from shear to plain brittle tensile failure, as the number of infiltrations increased.