激光表面改性对熔盐环境下热障涂层相稳定性和微观结构的影响  

Effects of Laser Surface Modification on Phase Stability and Microstructures of Thermal Barrier Coatings in V2O5 Molten Salt

作　　者：郭磊[1,2,3] 辛会[1] 张馨木[1] 叶福兴 高远 GUO Lei;XIN Hui;ZHANG Xin-mu;YE Fu-xing;GAO Yuan(School of Materials Science and Engineering,Tianjin University,Tianjin 300072,China;Tianjin Key Laboratory of Advanced Joining Technology,Tianjin 300072,China;Key Lab of Advanced Ceramics and Machining Technology of Ministry of Education,Tianjin 300072,China)

机构地区：[1]天津大学材料科学与工程学院,天津300072 [2]天津市现代连接技术重点实验室,天津300072 [3]先进陶瓷与加工技术教育部重点实验室,天津300072

出　　处：《表面技术》2020年第1期41-48,共8页Surface Technology

基　　金：国家自然科学基金(51971156)~~

摘　　要：目的改善Y2O3部分稳定ZrO2(YSZ)热障涂层的抗熔盐腐蚀性能。方法采用脉冲Nd:YAG激光系统对大气等离子喷涂YSZ热障涂层进行激光表面改性,优化激光参数,将喷涂态以及激光改性涂层在700℃和1000℃的V2O5熔盐下进行4 h热腐蚀实验。采用XRD、SEM和EDS表征腐蚀前后喷涂态和激光改性涂层的物相成分、微观结构和化学成分,通过计算热腐蚀后涂层表面的单斜(m)ZrO2含量,分析激光改性对涂层相稳定性的影响。结果涂层表面的激光改性层呈现致密柱状晶结构并有一些贯穿的垂直裂纹。与原始涂层一样,改性层呈现亚稳态(t′)四方相。改性涂层在700℃腐蚀4 h后,腐蚀产物为ZrV2O7、YVO4和少量m-ZrO2;在1000℃腐蚀4 h后,腐蚀产物为m-ZrO2和YVO4。对未改性的YSZ涂层进行相同条件下的熔盐热腐蚀,其腐蚀产物种类与改性涂层相同,但是m-ZrO2含量更高,表明更多的t'相受熔盐腐蚀而分解。结论激光改性可提高YSZ涂层中t'相的稳定性,使得涂层具有更好的抗熔盐腐蚀性能。然而,熔盐易沿垂直裂纹在改性层中渗入,不利于涂层的长期稳定性。This work aims to improve the corrosion resistance of Y2O3 partially stabilized ZrO2(YSZ)thermal barrier coatings to molten salt.In this study,A pulsed Nd:YAG laser system was applied to modify surfaces of air plasma spray(APS)YSZ coatings,and the laser parameters were optimized.The as-sprayed and laser-modified coatings were both exposed to hot corrosion tests at 700℃ and 1000℃ for 4 h in V2O5 molten salt.The phase constitution、microstructure and chemical composition of as-sprayed and laser-modified coatings before and after hot corrosion tests were characterized by XRD、SEM and EDS,and the effects of laser modification on phase stability of coatings were analyzed by calculating the content of m-ZrO2 on the surfaces of coatings after hot corrosion.Laser glazing layers on coating surfaces presented a dense columnar crystal structure,with some vertical cracks through the layer.Like the as-sprayed coating,the modified layer remained metastable tetragonal(t’)phase.Corrosion products of modified coatings corroded at 700℃ and 1000℃ for 4 h were ZrV2O7,YVO4 and small amounts of monoclinic(m)ZrO2,and m-ZrO2 and YVO4,respectively.Under the same molten salt corrosion conditions,the type of corrosion products of non-modified YSZ coating was the same as that of the modified coating,but with a higher m-ZrO2 content,which indicated that more decomposition of t’phase due to corrosion.Therefore,laser modification can improve the t’phase stability of YSZ coating,and the modified coatings have a better corrosion resistance to molten salt.However,molten salt penetration into the coating through the vertical crack in the glazing layer is undesirable,which is harmful to the long-term stability of the coatings.

关 键 词：热障涂层 等离子喷涂 YSZ 激光改性 V2O5腐蚀 

分 类 号：TG174[金属学及工艺—金属表面处理]