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 Al₄C₃ and 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^-6 mm³ N^-1 m^-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.