Improvement of Oxidation Resistance of SiC/C (graphite) Composites by Silicon Infiltration in Surface

摘要

SiC/C (graphite) composite ceramics with 20vol％ flake graphite were fabricated by Plasma Activated Sintering (PAS) firstly; the composites treated by silicon infiltration in surface were oxidized from 800°C to 1500°C. Effect of silicon infiltration on the oxidation resistance of SiC/C (graphite) composites was characterized by TG/DTA, SEM and XRD. The results show that the graphite in surface of composites reacted with silicon to form a dense SiC film about 30μm-in-thickness. The oxidation resistance temperature was increased from 600°C to 1300°C. Below 1300°C, the surface of composites by silicon filtration was oxidized to form a dense continuous oxide film to hider the oxidation of graphite in matrix. At 1500°C, the surface oxide film was heavy damaged, and many micropores were produced; inner graphite was oxidized above 1300°C again.