Production of Pure, Intimately Mixed Silicon Nitride/SiliconCarbide Powders by a Novel Gas Phase Combustion Synthesis Process

精细、超纯、均匀、松散团聚的颗粒， 用于高级陶瓷的理想起始材料。 的混合物 氮化硅和碳化硅特别有价值。 在 本方案采用硅烷/乙炔/氨气火焰， 将研究氮化硅/碳化硅粉末。具体 工作内容包括：（1）火焰稳定性的实验测定 对于选定的硅烷混合物的平焰燃烧器的限制， 氨和乙炔作为未燃烧气体速度的函数; (2)预期火焰温度的热力学确定， 产品收率作为输入组成、压力和 （3）初始温度; 条件对所生产的粉末的性质，特别是 什么样的操作条件决定了个人是否 颗粒是碳化物和氮化物的混合物，或者 氮化物和碳化物呈独立颗粒;（4）测定 产品特性（化学成分、纯度、颗粒 尺寸分布，形态）;和（5）解释 在机制和商业化潜力方面取得成果。 高质量的超细氮化硅/碳化硅粉末， 先进陶瓷制备的巨大潜在市场 材料通过烧结或热压。 生产进度 先进陶瓷的发展目前受到以下因素的限制： 一种美国制造的高质量粉末。 此外，了解 参与这一进程的机制将具有广泛的 燃烧合成的影响（特别是混合 材料）一般。

Fine, ultrapure, uniform, loosely agglomerated particles are desirable starting materials for advanced ceramics. Mixtures of silicon nitride and silicon carbide are particularly valuable. In this program, the use of silane/acetylene/ammonia flames to produce silicon nitride/silicon carbide powders will be studied. Specific tasks include: (1) Experimental determination of flame stability limits on a flat-flame burner for selected mixtures of silane, ammonia, and acetylene as a function of unburned gas velocity; (2) Thermodynamic determination of expected flame temperatures and product yields as functions of input compositions, pressure, and initial temperature; (3) Determination of the effects of operating conditions on the properties of the powder produced, specifically what operating conditions devermine whether the individual particles are a mixture of the carbide and nitride or whether the nitride and carbide are in separate particles; (4) Determination of the product properties (chemical composition, purity, particle size distribution, morphology); and (5) Interpretation of the results in terms of mechanisms and commercialization potential. High quality ultrafine silicon nitride/silicon carbide powders have a large potential market in the preparation of advanced ceramic materials via sintering or hot pressing. Progress in production of advanced ceramics is currently limited by the unavailability of a US-made high quality powder. In addition, an understanding of the mechanisms involved in this process will have broad implications for combustion synthesis (especially of mixed materials) in general.