2006 Volume 114 Issue 1335 Pages 867-872
Gas-pressure sintering of β- and α-silicon nitride powders has been investigated at 1800-2000°C under 980 kPa N2. The sintering behavior was detected by a dilatometer. Liquid phase sintering and grain growth of β powder is based on diffusion-controlled kinetics. The unimodal microstructure indicates a normal grain growth. With respect to β powder, there is an extra process for both sintering and grain growth of α powder. The nucleation of abnormal grains has been observed during phase transformation at the intermediate stage of sintering. At the final stage of sintering and grain growth, abnormal grains grow in the fine-grained matrix, resulting in in-situ reinforced microstructures. The grain growth behavior is to be discussed in relation to the driving force for grain growth. Finally, the control of microstructure is examined for in-situ reinforced microstructures and nano-ceramics.
