Microstructure and properties of C/C–SiC composites prepared by reactive melt infiltration at low temperature in vacuum

Dense C/C-SiC composites were prepared by reactive melt infiltration at 1100-1200 degrees C in vacuum through addition of 20-40 wt% Al into Si powder. XRD and EDS analysis showed that the composites were composed of carbon, SiC, Al and residual Si. The composite with 20% wt.% Al had the maximum compressive strength and modulus, while the composite with 30 wt% Al possessed the highest density and thermal expansion coefficient. The micro-cracks in composites were responsible for the compressive behavior, and caused decrease of thermal expansion of the composites from 30 to 40 wt% Al.