(1. 广州有色金属研究院 新材料研究所，广东 510650；
2. 日本国立丰桥技术科学大学 机械构造系统工学系，日本 丰桥 441-8580)
摘 要: 为了解环境压强对热喷涂熔滴沉积行为及涂层性能的影响机理，采用低压等离子喷涂装置在不同压强下向不锈钢SUS304基体上喷涂Ni粉末，在基体上收集一定数量的熔滴沉积物及涂层。采用光学显微镜、扫描电镜与聚焦离子束技术等对单个熔滴沉积物的形态进行观察分析，对不同压强下制备的涂层的微观组织、氧含量及结合强度等进行表征。对不同压强下基体表面吸附质的脱附/吸附、熔滴与基体间润湿能力、热传导及界面处的初期凝固等因素对熔滴在基体表面沉积行为的影响进行探讨。结果表明：单个熔滴的沉积形态由常压下的溅射状沉积到低压下的规则盘状沉积；不同压强下均可得到致密涂层，且涂层的结合强度随环境压强降低而逐渐增加，其变化趋势与单个熔滴沉积物形貌随压强变化趋势相吻合，可见熔滴的沉积行为对涂层的性能有着重要的影响。
关键字: 热喷涂；环境压强；扁平沉积物；涂层
（1. Department of New Materials, Guangzhou Research Institute of Non-ferrous Metals, Guangzhou 510650, China
2. Department of Mechanical and Structural System Engineering,
Toyohashi University of Technology, Toyohashi 441-8580, Japan）
Abstract:Aiming at clarifying the effect of ambient pressure on splat flattening behavior and coating performances in thermal spraying, Ni powders were thermally sprayed onto SUS304 substrates using low pressure plasma spraying (LPPS) at different ambient pressures. Individual splats and coatings were collected on the substrates under designated conditions. The splat characterizations were evaluated by optical microscopy, scanning electron microscopy and focused ion beam, respectively. The microstructure, oxygen content and adhesion strength of the coatings fabricated under atmospheric and reduced pressures were also characterized. The influencing factors, including adsorption/desorption of adsorbed gas condensation on substrate surface, wetting of substrate by molten droplet, heat transfer from molten droplet to substrate and the initial solidification at splat-substrate interface varied with ambient pressure on the splat formation process of thermal sprayed particles were systematically investigated. The results show that the shapes of the individual splat change transitionally from splash type to disk-shaped ones with the decrease of ambient pressure. Dense coatings can be achieved in low pressure plasma spraying. In particular, the coating adhesion strength increases gradually with the decrease of ambient pressure, which agrees well with the changing tendency of splat shape varying with ambient pressure. Therefore, the flattening behavior of the individual splat in thermal spraying process plays a very important role in the coating fabrication process.
Key words: thermal spraying; ambient pressure; splat; coating
