Effect of silicon addition on the microstructures and mechanical properties of porous SiC ceramics

The effect of Si addition in carbon foam on the microstructures and properties of porous SiC ceramics was studied. Porous SiC ceramics were prepared by infiltrating molten Si into carbon foam derived from the mixture of mesophase pitch and different amounts of Si powder. The microstructures, phase constitutions, porosity and flexural strength of porous SiC ceramics were analyzed and tested. The results showed that the porosity of the porous SiC ceramics decreases, and the strut density as well as flexural strength of porous SiC ceramics increase with the increase of the Si content. When Si content reaches 50%, the strut composed completely of SiC and the strut density is 3.14g/cm³. In addition, the highest flexural strength of 23.9MPa was attained at a porosity of 55%.