CMAS环境下PS-PVD 7YSZ涂层的抗热冲击性能及失效机制  

Thermal shock resistance and failure mechanism of CMAS deposited PS-PVD 7YSZ coating

作　　者：王允良[1,2] 邓畅光 詹肇麟[1] 张吉阜 

机构地区：[1]昆明理工大学材料科学与工程学院,云南昆明650000 [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,广东省现代表面工程技术重点实验室,广东广州510650

出　　处：《金属热处理》2017年第4期175-179,共5页Heat Treatment of Metals

基　　金：国家重点基础研究发展计划(973计划)(2012CB625100)

摘　　要：采用等离子喷涂-物理气相沉积(PS-PVD)工艺制备柱状7YSZ热障涂层,同时在7YSZ涂层表面沉积CMAS熔盐,研究在1250℃高温下,CMAS对柱状PS-PVD 7YSZ涂层抗热冲击性能的影响。采用SEM、EDS、XRD等检测方法分析热障涂层微观结构、元素分布和物相组成。结果表明:沉积CMAS熔盐的7YSZ涂层在热循环240次发生层离剥落失效,而未沉积CAMS的涂层无明显剥落,其热循环寿命明显优于沉积CMAS熔盐的7YSZ涂层。在CMAS和循环热冲击的耦合作用下,PS-PVD 7YSZ涂层失效机制为:在热冲击过程中,CMAS熔盐渗入并填充7YSZ涂层,引起渗透区和未渗透区热膨胀系数不均衡,从而产生热不匹配应力;此外,热冲击过程中由于温度梯度的存在也会引起温度梯度热应力,在这两种热应力的耦合作用下,引起涂层内部横向裂纹的产生,并随着热冲击次数的增加,横向裂纹发生扩展,最终导致涂层出现层离剥落失效。Columnar 7YSZ thermal barrier coatings were prepared by plasma spraying-physical vapor deposition（ PS-PVD）. The surface of7 YSZ coating was deposited with CMAS layer. The influence of CMAS deposits on PS-PVD 7YSZ thermal cycling performance was investigated. The microstructure evolution and phase transformation of TBCs were analyzed by SEM,EDS and XRD. The results show that the failure of 7YSZ coating with CMAS deposits occurs through spallation with layer by layer after 240 thermal cycles,while the 7YSZ coating without CMAS deposits have no obvious spallation and its thermal cycle life is significantly better than 7YSZ coating with CMAS deposits. The thermal cycling failure mechanism of PS-PVD 7YSZ coating with CMAS deposits is educed that in the thermal shock process,CMAS infiltrates and fills the porous 7YSZ coating resulting in thermal expansion coefficient mismatch between permeate and non-permeate zone accompanied by thermal mismatch stress. In addition,due to the presence of a temperature gradient,it will lead to temperature gradient thermal stress during the thermal shock process. Under the interaction of this two kinds of stress,transverse cracks generate in the internal7 YSZ coating. With the increasing times of thermal cycle,development of transverse cracks will occur resulting in spallation and failure.

关 键 词：等离子喷涂-物理气相沉积 循环热冲击 CMAS 失效 

分 类 号：TG174.442[金属学及工艺—金属表面处理]