Preparation and sintering of SiC particulate dispersed Al2O3 fine powders by spray pyrolysis method

SiC dispersed alumina fine powders were prepared by the spray pyrolysis method from a suspension using a two-fluid nozzle type atomizer. The raw suspension was obtained by dispersing SiC fine particles into 0.3 mol/l aluminum nitrate solution. The amount of SiC after sintering was varied from 8 to 34 vol%, which was about 70% of the initial mixtures. The alumina phase was amorphous. The surface areas of the as-synthesized powders were 28-39 m(2)/g, decreasing with increasing SiC content. The obtained particles were agglomerate of hollow spheres with outer diameter of 2-10 mum. Amorphous alumina turned to intermediate alumina(gamma/eta) at 900degreesC and alpha-alumina at 1100degreesC. In the hot-pressed composites using the spray-pyrolized powders, SiC particles were frequently included into alumina grains. Mechanical properties of the sintered bodies using the spray-pyrolized powders were comparable or higher than the sintered bodies prepared from a powder mixture of Al2O3 and SiC.