(1. 廣州有色金屬研究院 新材料研究所，廣東 510650；
2. 日本國立豐橋技術(shù)科學(xué)大學(xué) 機械構(gòu)造系統(tǒng)工學(xué)系，日本 豐橋 441-8580)
摘 要: 為了解環(huán)境壓強對熱噴涂熔滴沉積行為及涂層性能的影響機理，采用低壓等離子噴涂裝置在不同壓強下向不銹鋼SUS304基體上噴涂Ni粉末，在基體上收集一定數(shù)量的熔滴沉積物及涂層。采用光學(xué)顯微鏡、掃描電鏡與聚焦離子束技術(shù)等對單個熔滴沉積物的形態(tài)進行觀察分析，對不同壓強下制備的涂層的微觀組織、氧含量及結(jié)合強度等進行表征。對不同壓強下基體表面吸附質(zhì)的脫附/吸附、熔滴與基體間潤濕能力、熱傳導(dǎo)及界面處的初期凝固等因素對熔滴在基體表面沉積行為的影響進行探討。結(jié)果表明：單個熔滴的沉積形態(tài)由常壓下的濺射狀沉積到低壓下的規(guī)則盤狀沉積；不同壓強下均可得到致密涂層，且涂層的結(jié)合強度隨環(huán)境壓強降低而逐漸增加，其變化趨勢與單個熔滴沉積物形貌隨壓強變化趨勢相吻合，可見熔滴的沉積行為對涂層的性能有著重要的影響。
關(guān)鍵字: 熱噴涂；環(huán)境壓強；扁平沉積物；涂層
（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
