Fundamental Studies of High Pressure Self-Sustaining Synthesis of Silicon Nitride Based Ceramics

摘要-Puszynski这是一项研究在自持状态下高压合成氮化硅陶瓷的基本原理。所研究的方面包括颗粒-颗粒-气体相互作用、产物形态和燃烧合成陶瓷的相组成。重点研究了燃烧条件和各种添加剂的影响、可能改变晶体生长的因素以及氮化硅基陶瓷的形成机理。在含有大量氧化物、氮化物、卤素和/或碳的硅粉的自持高压氮化过程中，获得了关于氮化硅、氮化硅和碳化硅的形成和晶体生长的定量数据。建立了描述单相氮化硅和其他固溶体形成过程中粒子水平上的复杂反应和扩散过程的模型。较高的合成和加工成本限制了先进氮化物陶瓷的广泛应用。燃烧合成是克服这一障碍的一种有吸引力的方法。氮化硅基陶瓷因其化学惰性、高温稳定性、断裂韧性以及耐冲刷、腐蚀和热震等性能，在许多高科技领域具有广泛的应用前景。

Abstract - Puszynski This is a study of the fundamentals of high-pressure synthesis of silicon- nitride-based ceramics in a self-sustaining regime. Aspects investigated include particle-particle-gas interactions, product morphology, and phase composition of combustion-synthesized ceramics. The effort focuses on the effects of combustion conditions and various additives, factors that may alter crystal growth and the formation mechanisms of silicon-nitride-based ceramics. Quantitative data are obtained on the formation and crystal growth of silicon nitride, silicon oxynitride, sialon, and silicon carbide during self- sustaining, high-pressure nitridation of silicon powders containing amounts of oxides, nitrides, halogens, and/or carbon. Models are developed to describe the complex reaction and diffusion processes on a particle level during formation of single-phase silicon nitride and other solid solutions. Widespread application of advanced nitride ceramics is limited by high synthesis and processing costs. Combustion synthesis is an attractive method for overcoming this obstacle. Silicon-nitride-based ceramics are attractive for many high-technology applications because of their chemical inertness, high- temperature stability, fracture toughness and resistance to erosion, corrosion, and thermal shock.