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

9530258 Du将研究氮化硅材料在高温下在干氧和湿氧中的腐蚀。 将特别强调铝注入的影响，并将评估钠污染的影响。 将在腐蚀过程的各个阶段详细描述表面成分和微观结构，并将其与腐蚀速率相关联，腐蚀速率将通过原位厚度测量（包括激光反射率，并辅以非原位椭圆偏振和轮廓测量）确定。 将构建一个动力学模型来描述腐蚀过程，并评估腐蚀速率常数，速率控制物种的扩散率值，以及它们的温度依赖性。 ***

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. ***