中文摘要：

为了进一步提高等离子喷涂纳米Al2O3-13％TiO2（质量分数，下同）复合陶瓷涂层的性能，在γ-TiAl基体材料表面采用激光重熔工艺对涂层进行处理，研究了激光重熔对涂层微观组织和性能的影响。用扫描电镜（SEM）和显微硬度计分析了涂层形貌、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，等离子喷涂纳米陶瓷涂层由纳米颗粒完全熔化区和部分熔化区两部分组成，仍然具有等离子喷涂态的典型层状结构。经过激光重熔后，形成了致密细小的等轴晶重熔区、烧结区和残余等离子喷涂区，由于激光快速加热和快速冷却加工特点，在重熔区仍保留了部分来源于原等离子喷涂部分熔化区的残留纳米粒子。与常规等离子喷涂陶瓷涂层相比，纳米结构涂层可在一定程度上提高其硬度和耐磨性，经过激光重熔后其硬度和耐磨性进一步提高。

英文摘要：

In order to improve the properties of the nanostructured Al2O3-13%TiO2 composite ceramic coatings fabricated by plasma spraying, a laser remelting experiment was carried out and the effects of laser remelting on the microstructure and properties of coatings were studied. The morphology, microstructure and microhardness of the coatings were investigated by SEM and microhardness. Meanwhile, the wear behavior of the coatings was researched. The results show that the plasma-sprayed nanostructured ceramic coating consists of not only fully melted regions but also partially melted regions, and the total coating has a lamellar-like structure as conventional coating. According to the microstructural difference, the ceramic coating can be divided into the remelted zone （fine equiaxed grains）, the sintered zone and remained plasma-sprayed zone after laser remelting. The surface ceramic coating has smaller grains and higher compactness, and the lametlar structure of plasma-sprayed coating is eliminated. Due to the rapid heating and cooling of laser remelting, there are still some nanoparticles coming from the remained nanoparticles of plasma spraying in the remelted zone. The nanostructured ceramic coating has higher hardness, better wear resistance than the conventional ceramic coatings, and the laser-remelted coating has the highest hardness and the best wear resistance.