PS-PVD等离子射流特性的光谱诊断研究进展  

Research Progress in Spectroscopic Diagnosis of Plasma Jet Characteristics Under PS-PVD

作　　者：张岩 邓畅光 毛杰 邓子谦 罗志伟[1] ZHANG Yan;DENG Changguang;MAO Jie;DENG Ziqian;LUO Zhiwei(School of Materials Science and Engineering,Central South University,Changsha 410083,China;National Engineering Laboratory for Modern Materials Surface Engineering Technology,Guangdong Institute of New Materials,Guangzhou,510650,China)

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]广东省新材料研究所现代材料表面工程技术国家工程实验室,广州510650

出　　处：《中国表面工程》2019年第5期55-68,共14页China Surface Engineering

基　　金：国家自然科学基金(51771059);广东省科技计划项目(2014B070705007,2017A070701027,2017B030314122);广东省科学院项目(2019GDASYL-0104022,2017GDASCX-0111)~~

摘　　要：等离子喷涂-物理气相沉积(PS-PVD)作为一种新型喷涂技术融合了气相沉积与喷涂工艺两者的优点,其射流特性决定了涂层的结构与性能。光学发射光谱法(OES)作为一种等离子射流特性诊断技术,能实现射流特性原位检测,是判断射流内气化现象的有力手段。文中介绍了粉末送入前后及射流接触基体后射流特性的变化,展示了局部热力学平衡(LTE)假设及展宽理论下射流中各粒子状态的计算,探索了射流不同区域的传质传热等活动。Ar/He具有最高的温度,Ar具有高焓值对粉末的加热起主要作用,He凝聚射流能量对粉末的加热气化起关键作用,H2会扩展射流宽度降低射流温度易形成带有致密层的柱状结构。结合射流数值模拟和射流光谱图可知,喷枪内复杂的热交互作用是粉末加热的主要原因,喷嘴处膨胀/压缩区发生热能与动能的交替转换,而射流中后段由于低压与高温继续发生气化现象,达到峰值后射流处于冷凝降温阶段,部分气相原子凝聚成团簇状粒子。文中还总结了功率、电流和送粉率等对等离子射流特性的影响等。Plasma spray-physical vapor deposition(PS-PVD), as a new spray technology, combines the advantages of both vapor deposition and thermal spray processes. The plasma characteristics determine the micro structure and properties of the coatings. As a plasma jet characteristic diagnosis technology, optical emission spectroscopy(OES) can realize the in-situ detection of jet characteristics, which is a powerful means to judge the evaporation phenomenon in the jet. This paper introduced the changes of jet characteristics before and after the powder was inject and after the jet impacted the substrate. It shows the calculation of the state of each particle in the jet under the assumption of local thermodynamic equilibrium(LTE)and the theory of broadening, and explores the activities of mass and heat transfer in different regions of the jet. Ar/He has the highest temperature, and Ar has a high enthalpy value, which plays a major role in evaporating the powder. The He condensed jet energy plays a key role in the heating and evaporation of the powder. H2 expands the jet width and reduces the jet temperature to form a mixed layer with dense and columnar structure. Combined with simulation calcnlation and spectroscopy of the jet, it is known that the complex thermal interaction in the spray gun is the main reason for powder heating. The thermal energy and kinetic energy are alternately converted in the expansion/compression zone at the nozzle, and the middle and rear sections of the jet continue to vaporize due to low pressure and high temperature. After reaching the peak, the jet is in the stage of condensation and cooling, and some of the vapor phase atoms are agglomerated into cluster-like particles. The effects of power, current and powder feeding rate on plasma jet characteristics are also summarized.

关 键 词：等离子喷涂-物理气相沉积 等离子射流特性 光学发射光谱 热障涂层 局部热力学平衡 

分 类 号：TG174.44[金属学及工艺—金属表面处理]