Porous C/C composite with certain porosity prepared by Chemical vapor infiltration (CVI) was chosen as the preforms to develop the C/C-SiC composites through precursor infiltration and pyrolysis(PIP), using PCS (polycarbosilane) as the precursor and divinylbenzene as solvent and cross-linking reagent for PCS. The effect of the infiltration solution with different PCS/DVB ratio on the final density, microstructure, and mechanical properties of composites was investigated and the proper PCS/DVB ratio to prepare the C/C-SiC composites was suggested. The experimental results showed that the final densities and the mechanical properties of the composites were close related to the PCS/DVB ratio. Higher PCS/DVB ratio resulted in higher final density and better mechanical properties, but not the highest PCS/DVB ratio could get the best mechanical properties. The main reason is that too high PCS/DVB ratio will make the infiltration process become difficult and lead to the formation of lots of pores in the final composite, at last lowers the mechanical properties. It is believed that the 50% PCS content is proper to prepare the C/C-SiC composites. The composite from 50% PCS infiltration solution could get the final density of1.696g/cm3, the flexural strength of 171Mpa, and shearing strength of 21.6Mpa, which are the best mechanical results among the obtained materials.

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A series of carbon fiber reinforced C-SiC dual matrix composites (C/C-SiC composites) were developed through precursor infiltration of polycarbosilane (PCS) and pyrolysis (PIP), using porous C/C composites with different density from chemical vapor infiltration (CVI) as the preform. The density, mechanical properties, and microstructure of the composites were investigated and the effects of the preform density and the PCS concentration of the infiltration solution on the final density and the mechanical properties of the composites were discussed in detail. The results show that the final density of the C/C-SiC composites prepared at the infiltration concentration of 50% is the highest, indicating that 50% is the proper PCS concentration of the PCS/ Xylene solution to prepare the C/C-SiC composites. The final densities of C/C-SiC composites were closely related to the preform density and the highest final density corresponds to the highest original preform density. For the composites prepared using infiltration solution of 50% PCS, the C/C-SiC composite whose preform density is 1.23 g/cm3 possesses the best mechanical properties while that whose preform density is 1.49 g/cm3 the worst mechanical properties.

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