Effect of matrix gas phase deposition cycles on the microstructure and properties of 2D C/SiC

Effects of processing on the microstructure and property of carbon fiber reinforced silicon carbide matrix composites, namely 2D C/SiC composites, have been investigated with respect to micro-crack evolution, strength change and mass loss, etc. Several 2D C/SiC materials prepared with different chemical vapour infiltration (CVI) cycles of SiC were studied. Raman spectroscopy was employed to measure the residual stress in the matrix of the C/SiC composite based on the shift of the position of the LO band of SiC. Two kinds of mircocracks were found during the preparation of C/SiC. One type of cracks originating from the corners of braided holes barely changes during the whole processing, the other type arising between the braided holes decreases with increasing matrix volume. The former is most responsible for carbon fibers oxidation at elevated temperature. The evaluation of the microstructure and properties of the material is discussed in terms of the internal stress changed with the deposition of the matrix.