Synthesis and Processing of Silicon Nitride

In this chapter, only a very cursory assessment of the complexity of producing silicon nitride powders, and the processing of such powders to obtain monolithic shapes, will be provided. Further details of recent developments in this area may be found elsewhere (Petzow and Herrmann, 2002 lin et al., 2006). 

Powders The synthesis of siUcon nitride powders can be achieved in several ways that involve a variety of siUcon carriers such as elemental silicon, siUcon dioxide, and gaseous silicon tetrachloride and monosilane. Routes to siUcon nitride powders include the following technologies (Petzow and Herrmann, 2002)  

Carbothermal nitridation of silica, including rice huUs Diimide synthesis Vapor-phase synthesis Plasmachemical synthesis Laser-induced reactions Pyrolysis of organosilicon compounds 

For example, the diimide process involves the reaction of silicon tetrachloride or organyl aminosilane with ammonia and the subsequent thermal decomposition of the siUcon diimide according to  

In a different process, the high-temperature ammonolysis of SiCU in the gaseous phase between 800 and 1100°C leads to amorphous siUcon nitride that, on subsequent treatment at 1500°C, can be crystaUized to form a-Si3N4 (Patzold, 2001). 

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