钴铝钇共渗涂层组织形成机理及抗高温腐蚀行为研究

The gas turbine engine is the heart of airplane, and the advanced nickel based alloy is the most essential structural material in the engine. To meet the need that the gas turbine engine temperature keeps increasing as well as the long life under the severe circumstance, it is meaningful to study the oxidation and corrosion resistant coating to lengthen the nickel based alloy service life. The aim of the study is to investigate the effect of processing parameters on phase constitution, morphology, composition distribution and growth kinetics of the Co-Al-Y coating. Formation mechanism for the microstructure of the coating will be revealed. Corrosion kinetics of the coating, oxide microstructure, oxide growth mechanism, as well as adherence, will be investigated. Oxidation and corrosion resistant mechanism of the coating will be explored. At last, the coating failure mechanism and the major effect factors need to be studied as well. This project lays the foundation for developing the material and structure design theory and method for the protective coating on nickel based alloys.

燃气涡轮发动机是飞机的心脏，镍基高温合金是发动机中最为关键的结构材料，为满足燃气涡轮发动机温度不断提高以及发动机恶劣环境下长寿命要求，研究具有良好抗高温氧化腐蚀性能的涂层以提高镍基高温合金的使用寿命具有十分重要的意义。 本项目针对具有良好抗高温氧化腐蚀性能的Co-Al-Y共渗涂层，研究制备工艺参数对Co-Al-Y共渗涂层相组成、形貌、成分分布及生长动力学的影响规律，阐明Co-Al-Y共渗涂层的组织形成机理；研究Co-Al-Y共渗涂层的高温氧化腐蚀动力学、氧化膜的组织结构、氧化膜的生长机制及粘附性能，揭示涂层的抗高温氧化腐蚀机理，研究环境因素（如温度和气氛等）及涂层与基体的互扩散行为对Co-Al-Y共渗涂层服役寿命影响规律，揭示Co-Al-Y共渗涂层的失效机理及主要影响因素，为发展镍基高温合金表面具有良好抗高温防护涂层材料与结构的涉及理论与方法奠定基础。

本项目采用化学气相沉积方法，在Ni基高温合金表面制备了Co-Al和Co-Al-Y等共渗涂层。研究了钴和钴-稀土改性铝化物涂层的相组成和微观形貌，并揭示了涂层的组织形成机理。实验结果表明，涂层的生长属于外扩散型生长，主要归因于涂层中Ni的向外扩散。制备的涂层由外层和扩散层组成。外层主要为Al0.9Ni1.1相，其中部分Ni原子被Co原子取代。Y均匀弥散分布在涂层中但有部分聚集在外层与扩散层的界面上。研究了钴和钴-稀土改性铝化物涂层在高温静态氧化、循环氧化及热腐蚀条件下的高温氧化与腐蚀热力学、动力学以及氧化膜的组织结构及形成机理。Co-Al-Y涂层在1050ºC下静态氧化100 h的增重是0.50 mg/cm2，循环氧化寿命高达1185次；900ºC下静态热腐蚀100 h的增重仅为0.42 mg/cm2，Co-Al-Y涂层表现出了良好的抗氧化和抗热腐蚀性能。钴和稀土元素的协同作用促进了氧化铝膜的形成，增强了氧化膜与涂层表面的结合力，从而有效提高了涂层试样的抗高温氧化和热腐蚀性能。这些研究成果为舰载飞机发动机、推重比10及以上的航空发动机、舰船燃气轮机热端部件高温防护涂层的设计、制备及应用提供依据及保障。