CAREER: Coatings for High Temperature Alloys

9624927 Hampikian燃烧化学气相沉积（CVD）是一种新的化学气相沉积方法。由于CVD是在开放气氛中进行的，因此它有可能成为一种新的具有成本效益的涂层工艺。在本CAREER计划中，氧化铝涂层被应用于镍基合金原型，以评估CVD涂层对合金氧化性能的改善。通过使用含有不同浓度的活性元素掺杂剂的CVD涂层，研究了与活性元素效应相关的几个关键问题。通过对掺杂和未掺杂氧化铝鳞片的研究以及随后的表征，研究了活性元素添加抑制阳离子在氧化铝鳞片中的扩散的有效性。为了确定隔离/缺陷对假设的有效性，研究了临界浓度效应对这种抑制的机制。探讨了未涂覆合金和涂覆合金在高温腐蚀下的降解机理，以期大大增加该领域的现有知识库。这种类型的工作对于经历腐蚀性环境的零件的涂层系统的优化设计至关重要。例如，薄陶瓷涂层可用于提高块状材料的耐腐蚀性。涂层作为环境和基材之间的屏障，保护基材免受侵蚀和气体和液体腐蚀。＊＊＊

9624927 Hampikian Combustion chemical vapor deposition (CVD) is a novel approach to chemical vapor deposition. Because CVD is carried out in an open atmosphere, it has the potential to be a new cost-effective coating process. In this CAREER program coatings of alumina are applied to prototype nickel- base alloys to assess improvements in oxidation imparted to the alloys by the CVD coatings. Several key issues related to reactive element effects are examined through use of CVD applied coatings containing various concentrations of reactive element dopants. The effectiveness of reactive element additions in suppressing cationic diffusion in alumina scales is addressed through study of doped and undoped alumina scales and subsequent characterization. The mechanism of such suppression is explored for a critical concentration effect to ascertain the validity of the segregant/defect pair postulate. The mechanism of degradation of the uncoated and coated alloys to high temperature corrosion is explored with the goal of adding significantly to the current knowledge base in this area. %%% Work of this type is vital for optimum design of coating systems for parts experiencing aggressive environments. For example thin ceramic coatings can be used to improve the corrosion resistance of bulk materials. The coatings act as barriers between the environment and the substrate to protect the substrate from erosion and gaseous and liquid corrodants. ***