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热喷涂可磨耗涂层的三维显微结构
汤智慧1,2,3, 郭孟秋2,3, 周子民2,3, 高俊国2,3, 王长亮2,3
1.北京航空航天大学 材料科学与工程学院, 北京 100083;2.中国航空发动机集团 北京航空材料研究院, 北京100095;3.中国航空发动机集团 航空材料先进腐蚀与防护重点实验室, 北京 100095
摘要:
采用超音速火焰喷涂和大气等离子喷涂在高温合金表面制备由金属粘结层NiCoCrAlYTa和陶瓷面层Dy2O3稳定的ZrO2组成的可磨耗涂层,利用X射线显微镜(XRM)对涂层三维微观结构进行表征,结合扫描电子显微镜对经高温后的涂层孔隙、界面及裂纹演变进行研究。结果表明:在1100 ℃高温氧化条件下,随着氧化时间增加,粘结层中的富Ta相逐渐溶解并向晶界扩散,60 h后Ta元素完全固溶;粘结层/面层界面处形成双氧化层,由较致密均匀的氧化铝内层和混合氧化物外层构成;涂层的剥落失效主要由涂层中的裂纹缺陷导致,其在高温下优先沿界面、贯穿孔隙扩展。
关键词:  热喷涂涂层  三维微观结构  X射线显微镜  孔隙率  界面氧化物  裂纹扩展
DOI:10.11933/j.issn.1007-9289.20180708001
分类号:TG174.442
基金项目:国家自然科学基金(51605455)
Three-dimensional Microstructure of Thermal Spray Abradable Coatings
TANG Zhihui1,2,3, GUO Mengqiu2,3, ZHOU Zimin2,3, GAO Junguo2,3, WANG Changliang2,3
1.School of Material Science and Engineering, Beihang University, Beijing 100083, China;2.Beijing Institute of Aeronautical Materials Aero Engine Corporation of China, Beijing 100095, China;3.Key Laboratory of Advanced Corrosion and Protection for Aviation Materials, Aero Engine Corporation of China, Beijing 100095, China
Abstract:
The abradable coating including NiCoCrAlYTa bond coating and Dy2O3 stablished ZrO2 ceramic top coating was deposited on the superalloy by high velocity oxygen fuel (HVOF) and air plasma spray (APS) respectively. The three-dimensional microstructure of the coating was characterized by X-ray microscopy (XRM), and the evolution of pore, interface and crack of the coating were also studied by XRM and SEM. The results show that the Ta-rich phase in the bond coating dissolves gradually oxidated at 1100℃ and diffuses to the grain boundaries with increasing oxidation time. The Ta phase totally dissolves after oxidation at 1100℃ for 60 h. Double-layer thermally grown oxides are formed between the interface of bond/top coating, and the dual oxide layers is consisted of compact alumina inner layer and mixed oxides outer layer. The mechanism of coating spalling is mainly caused by the crack defects, which preferres to propagate along the interfaces and through the pores first at high temperature.
Key words:  thermal spray coating  three-dimensional microstructure  X-Ray microscope (XRM)  porosity  interface oxide  crack propagation