Preparation and tribological properties of SiC/rice bran carbon composite ceramics

Silicon carbide (SiC) ceramics have good wear resistance but poor friction properties under dry sliding conditions. To lower the friction of SiC, a novel porous carbon material called rice bran carbon (RBC) was added into SiC to make SiC/RBC composite ceramics. The SiC/RBC composites were prepared by mixing one of three kinds of RBC powders having different particle sizes and a fine SiC doped with Al₄C₃and B₄C additives and sintering at 1600 °C for 5 min by a pulse electric current sintering (PECS) method. The mechanical and tribological properties of the SiC/RBC composites were evaluated and compared with those of monolithic SiC, monolithic RBC bulk material, and SiC/graphite composite. The SiC/RBC composites not only had superior fracture strength (3–4 times as high as that of the monolithic RBC material) but also showed low friction coefficients (around 0.25) and high wear resistance (at a level of 10⁻⁶mm³N⁻¹m⁻¹) when slid against a silicon carbide ceramic counterface during block-on-ring sliding tests under dry conditions. Compared with the conventional SiC/graphite composite, the SiC/RBC composites had higher mechanical strength, lower friction coefficients, and better wear resistance.