Fine-grained silicon carbide ceramics with an average grain size of similar to140 nm or smaller were prepared by low-temperature hot-pressing of very fine beta-SiC powders using Al2O3-Y2O3-CaO (AYC) or Y-Mg-Si-Al-O-N glass (ON) as sintering additives. The microstructure stability of the resulting fine-grained SiC ceramics was investigated by annealing at 1850degreesC and by evaluating quantitatively the grain growth behavior using image analysis. The beta --> alpha phase transformation of SiC in AYC-SiC was responsible for the accelerated abnormal grain growth of platelet-shaped grains. In contrast, the beta --> alpha phase transformation in ON-SiC was suppressed, which resulted in a very stable microstructure. (C) 2004 Kluwer Academic Publishers.