Silicon nitride/SiAlON ceramics - A review

Advanced ceramic materials such as Si3N4 and SiAlON are reviewed here with particular reference to their synthesis, properties, and applications in va rious sectors such as transport and defense. It is noticed that synthesis b y the simultaneous carbothermic reduction and nitridation (CTR) is relative ly easy and economical. The products thus obtained by CTR, have unusual com bination of unique properties, viz., high strength at higher temperature, c hemical inertness, wear resistance, etc., and therefore they are very much useful in high-tech areas. In addition, some of the leading manufacturers o f Si3N4/SiAlON are listed in this paper. Ceramic whisker growth mechanism a nd its importance in improving the mechanical properties of ceramic matrix composites (CMCs) are also discussed. This paper is mainly intended to cove r important properties like structural, mechanical, oxidation/corrosion and wear resistance of Si3N4 and SiAlON.