In this study, pressureless sintering of silicon carbide whisker (SiC(w))-reinforced alumina composites was investigated. SiC whiskers or Al2O3 powders were coated with amorphous silica, and sintering behaviour was analysed according to the powder characteristics of the composite. It was found that amorphous silica coatings improved densification as compared with uncoated powders, because the viscous flow allows the release of any tensile stress due to differential shrinkage between the matrix and the silicon carbide whiskers. Mullite occurred when amorphous silica coatings reacted with alumina at approximately 1500-degrees-C, which resisted the viscous sintering of the amorphous silica coatings.