Microstructure and mechanical properties of Si-SiC composites

Reaction bonded Si-SiC composites were prepared by a silicon infiltration technique at temperature of 1600 degrees C for 30 minutes in vacuum. The microstructure and mechanical properties of Si-SiC composites were investigated and characterized. UF-15 and SE-10 as SiC powders, phenolic resin and carbon black as carbon sources, and metallic silicon powder as molten Si source were used. New SiC crystallines nucleated and grown by the reaction of Si and C were detected by TEM and SEM-EDS. The bonding between new and original SiC was found to be strong. But the wetting of SiC by unreacted metallic Si and the rapid grain growth of new SiC decreased density and fracture toughness. Fracture toughness and modulus of rupture of Si-SiC composite were about 3.2 MPa.m(1/2) and 480 MPa, respectively.