Influence Of Interfacial Strength Of CFRP On Microstructure And Properties C/C-SiC Composites

C/C-SiC composite has been considering as the promising materials for high temperature technologies. However, the performance of C/C-SiC composite is quite dependent on the microstructure and volume fraction of SiC matrix. It has been known that the interfacial strength of CFRP has a strong influence on the microstructure and properties of C/C-SiC composites. Therefore, in order to understand role of interfacial strength of CFRP on the microstructure and properties of C/C-SiC composites, in the current work, the interfacial strength of CFRP was changed by treating the fiber at elevated temperatures. And then, the silicon melt infiltration technique combined with the pyrolysis of phenolic resin was applied to fabricate the2D C/C-SiC composites. The main work is summarized as follows:(1) After heat treatment, the mechanical properties and the surface composition of carbon fibers were measured by the single filament tensile test technique and XPS, respectively. Result found that the surface composition has a significant change after treatment, but fiber strength has no obvious degradation. The interfacial strength measured from short-beam shear test and single fiber push-out test indicated that the heat treatment can modify the interfacial strength of CFRP effectively.(2) CFRP with different interfacial strength were pyrolisized to obtain the C/C preform. It was found that the distribution of pores and microcracks of C/C preform are strongly dependent on the interfacial strength of CFRP.(3) A model was constructed considering the parameters such as temperature, infiltration time, pore size, viscosity and surface tension of liquid silicon, to simulate the infiltration and reaction dynamics. This result provided some useful information for the adjustment and optimization of fabrication process.(4) By using the different C/C preform, the C/C-SiC composites were fabricated. The mechanical properties, phase analysis and oxidation test indicated the C/C-SiC composite fabricated from the CFRP with low interfacial strength shows ralative low flexural strength, but the oxidation resistance and homogeneity of SiC distribution were improved significantly.