Mechanical properties of SiC composites incorporating SiC-coated multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were coated with a nanometer-sized SiC polycrystalline layer by the reaction of SiO(g) and CO(g). Nanometer-sized SiC powders were mixed with 1–5 vol% SiC-coated MWCNTs and successfully sintered at 1800 °C by means of pulsed electric current sintering. These composites showed superior microhardness of 30.6 GPa and toughness of 5.4 MPa m1/2 compared to monolithic SiC ceramics due to the improvement of adhesion between MWCNTs and the SiC matrix by the SiC coating. The microhardness and toughness of the monolithic SiC ceramics are 25.5 GPa and 4.8 MPa m1/2, respectively. The SiC-coated MWCNTs/SiC composites showed an interesting behavior with the elastic recovery when undergoing an indentation test.