Advanced Sintering Techniques Research Articles

Development of High Performance Silicon Nitride Ceramics and their Applications

ABSTRACTProgress in sintering process and improvement of mechanical properties of silicon nitride ceramics are reviewed. Emphases are placed on contributions of advanced sintering techniques and better understanding of sintering additives and microstructure-properties relations. Current applications as engine components and cutting tools are described, and future prospect is considered.

Stability of Si3N4 and Liquid Phase(s) During Sintering

Advanced sintering techniques for consolidation of Si3N4 powders in the presence of an oxygen‐rich liquid phase(s) require high temperatures and usually high nitrogen pressures. A stability diagram is constructed for Si3N4 as a function of the partial pressures of nitrogen (PN2) and silicon (PSi). High PN2 (20 to 100 atm) increases the stability of Si3N4 and the oxygen‐rich liquid phase by reducing the PSi and PSi0, respectively. The region of high sinterability is outlined for submicrometer Si3N4 powders containing 7 wt% BeSiN2 and 7 wt% SiO2 as densification aids.