Role of Aluminum Surface Alloying in Improving the CorrisionResistance of Silicon Nitride Ceramics in Harsh Environments

研究了氮化硅材料在干湿氧中的高温腐蚀。特别强调铝注入的效果，并对钠污染的影响进行评价。表面组成和微观结构将在腐蚀过程的各个阶段进行详细表征，并与腐蚀速率相关联，腐蚀速率将通过使用激光反射的现场厚度测量来确定，并辅以非原位椭偏仪和轮廓测量。将建立一个动力学模型来描述腐蚀过程，并评估腐蚀速率常数、速率控制物质的扩散系数值及其温度依赖性。＊＊＊

9530258 Du The corrosion of silicon nitride materials at high temperature in dry and wet oxygen will be studied. The effects of aluminum implantation will receive special emphasis and the effects of sodium contamination will be evaluated. The surface composition and microstructure will be characterized in detail at various stages of the corrosion process and correlated with corrosion rates which will be determined by in-situ thickness measurements involving laser reflectance complemented by ex-situ ellipsometry and profilometry measurements. A kinetic model will be constructed to describe the corrosion process and to evaluate corrosion rate constants, diffusivity values of rate-controlling species, and their temperature dependence. ***