SiC/Al composites were fabricated by pressureless infiltration technique, based on infiltration dynamics mechanism and technic method ,the effects of holding time and cooling way on the residual porosity of composites were discussed.

Through analyzing the fracture microstructure, measuring line-shrinkage rate, density and residual porosity of sintered sample, the influence of sintering temperature on density and the influence of the type of dispersant on residual porosity of sintered sample were studied.

After making fracture analysis, chemical analysis and metallographic examination to the broken ped estal, It is concluded that the main reason are the harden layer,original crack and shrinking hole remnant flaw existing on the raw material.