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干氧和湿氧中的高温腐蚀。铝离子注入的效果将受到特别重视，并将评估钠污染的影响。表面成分和微观结构将在腐蚀过程的不同阶段得到详细的表征，并与腐蚀速度相关联，这将通过包括激光反射的原位厚度测量以及非原位椭偏测量和轮廓术测量来确定。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、速率控制物种的扩散系数值及其与温度的关系。***

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. ***