Nanocomposite powders from coating with heterogeneous nucleation processing

A nanocomposite SiC powder was prepared by coating nano-SiC particles with Y(OH)3 and/or Al(OH)3 via heterogeneous nucleation processing using a buffered pH solution as the precipitation reagent. TEM micrographs showed the coating materials nucleated and grew on the surface of nano-SiC and did not form sol particles in solution. The isoelectric point (IEP) of coated SiC was different from that of as-received SiC. The IEP of Al(OH)3-coated SiC occurred at pH 7.3, which is close to that of alumina. When Al(OH)3-coated SiC particles were coated with Y(OH)3,the IEP of nanocomposite powder shifted from pH 7.3 to pH 8.6, which is close to that of yttria. In addition, the dispersability of Al(OH)3-coated SiC was greatly improved when it was coated using heterogeneous nucleation processing.