Coating of SiC Powder with Nano YAG Phase

SiC-YAG(Y3Al5O12) ceramic composite powders were prepared by co-precipitation coating method. Mechanism of co-precipitation coating of SiC powders with Y^3+ and Al^3+ precursors was investigated. If the concentration of [OH^-] ion in the solution is controlled within the range between critical values for heterogeneous nucleation and homogeneous nucleation, Y^3+ and Al3^+ precipitation precursors can be coated on the surface of SiC particles, Y^3+ and Al^3+ precipitation precursors transform into YAG phase after calcining at 1000℃ without the formation of YAM and YAP phases. The formation temperature of YAG phase is about 600℃ lower than that of conventional powder mixing method. The effect of pH value of the solution and precipitant titration rate on coating quality of SiC-YAG composite powders was also studied. The results show that co-precipitation coating can be realized at a final pH of 9 and a precipitant titration rate of 5ml·min^-1.