热喷涂金属涂层与陶瓷涂层同样具有层状结构特征，其层间有限的结合控制着涂层性能。与氧化物陶瓷涂层不同之处在于，大气氛中喷涂金属涂层时金属粒子表面可能出现氧化膜，使得界面形成金属冶金结合过程更加复杂。本项目基于等离子喷涂陶瓷粒子形成结合存在临界温度的最新研究进展与金属熔融粒子温度可大幅度调控的特点，提出了通过真空等离子喷涂实现在有氧化膜、氧化膜厚度可控的条件下沉积扁平粒子，采用FIB制样与HR-TEM研究金属粒子界面结构与结合形成规律的思路。研究阐明无氧化膜下沉积温度对金属粒子界面结合形成规律与机制、氧化膜厚度对粒子界面结合形成规律与结合性质的影响规律、高温熔滴碰撞引起同质材料表面微区熔化与分散基体表面氧化膜的规律与机制，揭示金属熔滴碰撞形成冶金结合机制。为理解至今尚未解决的大幅度提高等离子喷涂金属涂层粒子界面结合的难题、通过调控粒子界面冶金结合比率显著提高涂层性能提供新的方法。

It is well known that there exists only a limited bonding between splats in both thermal spray metal and oxide coatings, which dominates their coating properties and performance. The possible oxide film evolved on metal splat surface during deposition makes it more difficult to improve metal coating cohesion and even investigate lamellar interface bonding nature than ceramic coating. Thus, there is no any effective approach to enhance the bonding between lamellae in the as-sprayed metal coatings yet. Based on the lasted advances on the relationship between the splat critical bonding temperature and ceramic material properties and taking account of obtainable wide temperature range of molten metal droplets in plasma spraying, in the present project it is proposed to investigate the effect of deposition temperature on the inter-lamellae bonding to the oxide-free metal surface and oxide-covered surface but at different thicknesses using vacuum plasma spraying system. The splats will be deposited with the molten droplets at different temperatures on the substrate with the identical compositions to splat at different deposition temperature to simulate the intersplat bonding formation. The bonding nature will be examined by HR-TEM through FIB-sampled dedicate interface samples. The investigations are aimed at clarifying the effect of deposition temperature on the splat bonding formation to both oxide-free and oxidized substrate, effect of oxide film on the bonding formation, interface bonding nature and mechanisms involved. The study also focuses on the molten conditions to cause the substrate surface layer melting and disperse the oxide film on substrate surface on impact to form metallurgical bonding. Thereafter, the bond formation mechanisms will be clarified. The formation mechanism of a metallurgical bonding between impacting droplet and identical substrate will be ascertained to propose a new approach to significantly increase the lamellae bonding ratio in thermal spray metal coatings. Moreover, the relationships between lamellar bonding ratio and typical coating properties will be established to provide a guideline for increasing lamellar interface bonding ratio, the performance of plasma-sprayed metal coating and consequently provide an effective solution to the bonding enhancing problem for extending application fields of thermal spray metal coatings.