Influence of silicon infiltration on the wear and oxidation resistance of hot-pressed B4C/C(graphite) composites

Abstract

B 4 C/C(graphite) composites were produced using Hot-pressing. However, the composites exhibited low surface hardness, low wear resistance as well as low oxidation resistance. The hot-pressed B 4 C/C(graphite) composites were processed via silicon infiltration procedure at 1550 °C for 2 h in the vacuum condition to refine the wear resistance, surface hardness, and oxidation resistance of the B 4 C/C(graphite) composites. The silicon infiltration process resulted in the fabrication of a surface layer based on silicon carbide and silicon upon the B 4 C/C(graphite) composites surface. The surface layer of the silicon infiltrated B 4 C/C(graphite) composites, primarily comprising silicon carbide and silicon, was examined for its phase composition and microstructure. The oxidation resistance, wear resistance, and surface hardness of B 4 C/C(graphite) composites subjected to silicon infiltration was additionally examined. The XRD results confirmed that silicon carbide and silicon-based layer existed on the surface of B 4 C/C(graphite) composites, which was produced as a result of the silicon infiltration process. The surface of silicon infiltrated B 4 C/C(graphite) composites exhibited a 300–400 μm thick covering of silicon carbide and silicon. The deposited layer also exhibited a dense and compact microstructure. When compared to hot-pressed B 4 C/C(graphite) composites, the surface hardness and wear resistance of the composites resulting after silicon infiltration were significantly enhanced. Silicon infiltrated B 4 C/C(graphite) composites possess a surface hardness of 16–17 GPa. The oxidation resistance of the silicon infiltrated B 4 C/C(graphite) composites was considerably enhanced as compared to the hot-pressed B 4 C/C(graphite) composites. So the silicon infiltrated B 4 C/C(graphite) composites exhibited high surface hardness, excellent wear resistance and excellent oxidation resistance in comparison with the hot-pressed B 4 C/C(graphite) composites.