Silicon carbide foams produced by siliciding carbon foams derived from mixtures of mesophase pitch and nano-SiC particles

Silicon carbide foam with high bending strength and well oxidation resistance was prepared by infiltrating liquid silicon into carbon foam derived from mesophase pitch added with nano-SiC particles. Microstructure observation and phase identification of resultant foams were performed by scanning electron microscope and X-ray diffraction, respectively. Bending strength and bulk density of final SiC foams were also measured and calculated. Oxidation resistance of foams was appraised by the analysis of thermogravimetric curves of specimen in flowing air from room temperature to 1473 K. Results showed that addition of nano-SiC particles could significantly reduce the crystal size and compact struts during the infiltration of liquid silicon into carbon foams, which results in the increase of bending strength of silicon carbide foams. As the addition amount of nano-SiC was 15 wt%, silicon carbide foams with low bulk density of 0.54 g/cm3 were obtained, which possessed high bending strength of 11.96 MPa and excellent oxidation resistance.