Preparation and characterization of SiC hollow microspheres

We present the method of chemical vapor deposition-pyrolysis for the fabrication of SiC hollow microspheres. Microspheres with a diameter of approximately 480-550 µm and wall thickness of 5-15 µm are thus successfully prepared. The composition, especially the C/Si atomic ratio, and surface morphologies of the SiC microspheres can be flexibly adjusted by controlling the coating and heating parameters. The SiC microspheres mainly contain CSi bonds with C/Si atomic ratios of approximately 1-3. The precursor microspheres are found to exhibit a large volume shrinkage (39-55%) during the pyrolysis process, while pyrolysis has a negligible impact on the yield of the SiC microspheres (>95%). The spherical degrees are greater than 98% with small dispersions. The wall thickness uniformities can be optimized as high as 95%. The density of SiC microspheres can be increased by prolonging the holding time at 450 °C, while the corresponding RMS roughness can be decreased.