INTERLAMINAR SHEAR STRENGTH OF C-SIC BASED COMPOSITES REINFORCED WITH HEAT TREATED CARBON FIBERS

摘要

Carbon fiber reinforced C-SiC based composites (C/C-SiC) are potential materials for the application of high-performance structures. Among many fabrication techniques for C/C-SiC composites, the liquid silicon infiltration (LSI) process is an attractive one because of its near-net shaping technique and good performance/cost benefits [1-4]. The manufacturing of C/C-SiC composites via the LSI process consists of three steps: (i) manufacturing of carbon fiber reinforced plastic (CFRP) green body; (ii) obtaining of porous C/C preform by converting polymer matrix into carbon at temperatures above 900 °C (carbonization step); (iii) fabrication of C/C-SiC composite through the liquid silicon infiltration into the C/C preform to form SiC matrix (siliconization step). At the different steps, the material shows a very different morphology. Especially, at the carbonization step, the shrinkage of the resin matrix caused by the evolution of gaseous products exhibiting a volume reduction of more than 50% is hindered by the stiff fiber. This leads to an extensive formation of network of both pores and cracks in the carbon matrix. During the siliconization step, the pores and cracks essentially act as the channel for the liquid silicon climbing into the inner parts being reacted with the carbon matrix or fiber to form the silicon carbide. Eventually, the matrix of C/C-SiC composites fabricated in such way includes amorphous carbon, silicon carbide and a small amount of residual silicon [2].