(1. 南京航空航天大学 机电学院， 南京 210016;
2. 南通工学院 机械工程系, 南通 226007;
3. 江苏大学 机械工程学院， 镇江 210013)
摘 要: 采用X射线衍射仪、 扫描电镜和显微硬度计研究了45#钢表面激光熔覆纳米Al2O3改性Al2O3+13%TiO2（质量分数）陶瓷涂层的相组成、微观结构和显微硬度， 同时对涂层的磨损特性进行了考察。 结果表明， 激光重熔区亚稳相γ-Al2O3转变成稳定相α-Al2O3， 熔覆层由粗颗粒α-Al2O3和TiO2以及纳米α-Al2O颗粒组成， 在激光的作用下， 等离子喷涂层的片层状结构得以消除；纳米Al2O3颗粒仍然保持在纳米尺度，填充在涂层的大颗粒之间， 使涂层致密化程度得以提高， 因此纳米Al2O3改性涂层的显微硬度较高，且其耐磨性能明显优于等离子喷涂层。
关键字: 纳米Al2O3颗粒； Al2O3； TiO2； 等离子喷涂；复合陶瓷涂层； 激光熔覆
Al2O3 nano-particles
（ 1. College of Mechanical and Electrical Engineering,
Nanjing University of Aeronautics and Astronautics,
Nanjing 210016, China;
2. Department of Mechanical Engineering,
Nantong Institute of Technology, Nantong 226007, China;
3. College of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China）
Abstract: The phase constitution, microstructure and microhardness of Al2O3+13%TiO2(mass fraction) composite ceramic coatings laser-claded by Al2O3 nano-particles on 45# steel were investigated using X-ray diffractometry, scanning electron microscopy and microhardness measurement. Also, wear behavior of the coatings was studied. The results show that the metastable γ-Al2O3 phases in the cladding area transfer into stable phase of α-Al2O3, composite ceramic coating consists of α-Al2O3 and TiO2, and lamellar structure of plasma-sprayed coatings is eliminated after the laser-cladding. A large number of Al2O3 nano-particles are found among the large particles of the ceramic coating and play an important role in improving the density of the ceramic coating. So laser-claded nano-Al2O3 ceramic coating has higher hardness and better wear resistance than plasma sprayed Al2O3+13%TiO2 coating does.
Key words: Al2O3 nano-particle; alumina; titania; plasma spraying; composite ceramic coating; laser cladding
