等离子喷涂熔滴铺展凝固行为研究现状  

Research Status of Molten Droplet Spreading and Solidification Behaviour in Plasma Spraying

作　　者：肖嵩 刘明 张小龙 黄艳斐 王海斗 XIAO Song;LIU Ming;ZHANG Xiaolong;HUANG Yanfei;WANG Haidou(College of Mechanics and Power,China Three Gorges University,Yichang 443002,Hubei,China;National Key Laboratory for Remanufacturing,Army Academy of Armored Forces of PLA,Beijing 100072,China)

机构地区：[1]三峡大学机械与动力学院,湖北宜昌443002 [2]中国人民解放军陆军装甲兵学院装备再制造技术国防科技重点实验室,北京100072

出　　处：《材料导报》2024年第6期179-190,共12页Materials Reports

基　　金：国家自然科学基金(52075542,52130509,52105235);十四五预研项目。

摘　　要：等离子喷涂实质上是以等离子气体为热源,将金属或陶瓷粉末加热成具有一定温度和速度的熔滴,并撞击基体表面而在基体上铺展凝固的过程,该过程对涂层质量具有重要影响。本文从单个和多个熔滴的铺展凝固行为、铺展凝固的影响因素以及熔滴凝固时产生键合和裂纹的原因三个方面,综述了等离子喷涂过程中熔滴撞击、铺展、凝固过程。当冷却速率不同时,熔滴撞击基体后会出现先铺展后凝固和边铺展边凝固两种行为;由于后续熔滴撞击位置的不同,材料会出现不同类型的孔隙;由于晶格参数和过冷度的不同,凝固方式主要有非稳态凝固和外延生长;影响铺展凝固的因素有气体捕获、熔滴底层凝固和基体预热等;提高粒子温度和基体温度、减少基体传热可以促进凝固过程中界面结合;合适的分段裂纹密度可以显著提升涂层性能。通过研究熔滴铺展凝固行为和堆叠过程,可以明确涂层内部缺陷的形成原因,完善对涂层形成机理的认识,更加科学地指导涂层质量调控。Plasma spraying is essentially a process of using plasma gas as a heat source to heat metal or ceramic powder to droplets under a certain temperature and speed.These droplets hit,spread and solidify on the surface of the substrate.This process has an important impact on the quality of the coating.In this paper,three aspects of the process of droplet impact,spreading,and solidification in plasma spraying are summarized:the spread-solidification behaviour of single and multiple droplets,factors influencing spread-solidification,and causes of bonding and cracks during droplet solidification.When the cooling rate differs,the molten droplets first spread and then solidify,or they solidify while spreading after hitting the substrate.Different types of pores appear because of the different positions of the subsequent droplet impacts.Given the different lattice parameters and subcooling degrees,the solidification mode primarily includes unsteady solidification and epitaxial growth.The factors affecting spread-solidification are gas capture,droplet bottom solidification,and matrix preheating.Increasing the particle and matrix temperatures and reducing the heat transfer of the matrix can promote interfacial bonding during solidification,and the appropriate piecewise crack density can improve the performance of the coating significantly.Examining the droplet spread-solidification behaviour and stacking process can clarify the cause of formation of internal defects in the coating and improve understanding of the formation mechanism of the coating.Thus,the quality control of the coating can be guided more scientifically.

关 键 词：等离子喷涂 铺展行为 凝固机理 衬底温度 冶金结合 裂纹 

分 类 号：TG174[金属学及工艺—金属表面处理]