SiC/C machinable ceramics surface hardening by silicon infiltration

SiC/20 vol.% C(graphite) composites were fabricated by plasma-activated sintering. The Vickers hardness was 5.8 GPa because of the existing of graphite and weak interface between the graphite and the SiC. Specimens were treated by silicon infiltration, which improved the surface Vickers hardness (24 GPa). X-ray diffraction results showed that the graphite in the surface reacted with liquid silicon to form SiC. Scanning electron microscopic observation indicated that the continuous film was dense and approximately 25 μm in thickness in the top surface. For the hardening surface, the oxidation and wear resistance were improved.