Effect of calcination process on the properties and microstructure of SiC preform and corresponding SiCp/Al composites synthesis by pressureless infiltration

The influence of calcination time and temperature on the property and microstructures of the SiC preform prepared by ceramic injection molding and corresponding SiCp/Al composites by pressureless infiltration was investigated. It was found that the commutative bonding of generated SiO2 layer on the surface of the SiC was the source of obturated pores and strengthened the preform. The effect of the temperature on the open porosity ratio (POPR) and strength of the preform was more than that of calcination time because the diffusion of oxygen in the oxide layer was controlled by the temperature, not by the time. The aluminum could destroy the obstacle of SiO2 during the infiltration by the interface reaction and infiltrated the obturated pores so that the porosity of the composite was lower than the obturated porosity of the corresponding preform. A better calcination condition was found to be at 1100 °C for 8 h in vacuum at which the compressive strength of the preform was about 0.4 MPa and the porosity of the corresponding composites was below 0.3% though the obturated porosity ratio of the preform was as high as 2.6%.