(1. 南京航空航天大学 江苏省精密与微细制造技术重点实验室，南京 210016；
2. 南京航空航天大学 机电学院，南京 210016)
摘 要: 以Al2O3-13%TiO2(质量分数)团聚体复合陶瓷粉末为材料，采用等离子喷涂工艺在TiAl合金表面制备纳米结构陶瓷涂层。用扫描电镜(SEM)和X射线衍射仪(XRD)分析粉末和涂层形貌、微观结构及相组成，讨论涂层的微观组织形成机理。结果表明：纳米结构复合陶瓷涂层由部分熔化区以及与常规等离子喷涂类似的片层状完全熔化区组成；根据组织结构的不同，部分熔化区又分为液相烧结区(亚微米A12O3粒子镶嵌在TiO2基质相的三维网状或骨骼状结构)和固相烧结区(经过一定程度长大但仍保持在纳米尺度的残留纳米粒子)；等离子喷涂使部分α-A12O3以及全部θ-A12O3转变为亚稳态γ-A12O3；纳米结构复合陶瓷涂层中的完全熔化区、液相烧结区及固相烧结区分别由等离子喷涂过程中纳米团聚体粉末中温度高于A12O3熔点、介于TiO2熔点到A12O3熔点之间以及低于TiO2熔点区域沉积获得，纳米结构涂层中不同部分熔化组织源于复合陶瓷粉末中A12O3与TiO2之间的熔点差异。
关键字: Al2O3-13%TiO2纳米复合陶瓷涂层；等离子喷涂；纳米团聚体粉末；形成机理
（1. Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology,
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
2. College of Mechanical and Electrical Engineering,
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China）
Abstract:The nanostructured ceramic coatings were fabricated on TiAl alloy surface by plasma spraying with agglomerated Al2O3-13%TiO2 (mass fraction) powders. The morphology, microstructure and phase of the powders and coatings were investigated by scanning electron microscopy and X-ray diffractometry. The formation mechanism of the coating was discussed. The results show that the nanostructured ceramic coating consists of the fully melted regions and the partially melted regions, and the fully melted region has a lamellar-like structure as the conventional coating. According to different microsturctures, the partially melted regions are divided into liquid-phase sintered regions such as a three-dimensional net or skeleton-like structure, Al2O3-rich submicron particles distributing in the TiO2-rich matrix, and solid-phase sintered regions such as remained nanoparticles. Partially α-A12O3 phase and all θ-A12O3 phase in the nanostructured powder change to γ-Al2O3 after plasma spraying. The fully melted region, liquid-phase sintered region and solid-phase sintered region of nanostructured composite ceramic coating are derived from the region of the nanostructured agglomerated powders, where the temperature is beyond 2 045 ℃ (melting point of Al2O3), ranging between 1 840 (melting point of TiO2) and 2 045 ℃, and less than 1 840 ℃ during plasma spraying, respectively. The formation of the solid-phase and liquid-phase sintered regions in the partially melted region is attributed to the melting point difference between A12O3 and TiO2.
Key words: Al2O3-13%TiO2 nanostructured composite ceramic coating; plasma spraying; agglomerated powder; formation mechanism
