TC4激光熔覆Ti/7YSZ复合热障涂层实验研究  

Experimental study on the characterics of Ti/7YSZ composite thermal barrier coating by TC4 laser cladding on surface

作　　者：杨广峰[1] 翟巍 路梦柯 张杭 庞铭 崔静[1] YANG Guang-feng;ZHAI Wei;LU Meng-ke;ZHANG Hang;PANG Ming;CUI Jing(Airport College,Civil Aviation University of China,Tianjin 300300,China)

机构地区：[1]中国民航大学机场学院,天津300300

出　　处：《激光与红外》2021年第8期971-979,共9页Laser & Infrared

基　　金：中国民航大学蓝天青年学者培养经费项目;国家自然科学基金项目(No.U1933107);中央高校科研基金项目(No.ZXH2012D013)资助。

摘　　要：为提升YSZ隔热涂层的力学性能,阐明其组织形成过程及机理,优化激光加工工艺参数。方法采用YLS-3000型光纤激光系统利用激光熔覆技术在TC4表面制备了Ti/7YSZ复合涂层体系;通过光学显微镜、扫描电镜、能谱仪、X射线衍射仪和硬度仪分别表征激光熔覆Ti/7YSZ复合热障涂层的宏观形貌、显微组织、元素分布、物相组成及硬度分布。结果在不同激光扫描速度下,熔覆层表面呈不同程度黄色,微观组织均具有“上下细密、中间粗大”特征,其主要由针状α′马氏体、马氏体核心、α相集束、残余β相以及以TiC为代表的MC碳化物构成,Zr元素富集在基体与熔覆区的结合区;随着扫描速度的增加,Zr元素分布愈发不均匀,熔覆区内马氏体混乱、破碎程度加剧,显微硬度先增后减,7 mm/s时熔覆层与基体结合良好,硬度水平达到峰值600 HV,达TC4基体的2.5倍,熔覆质量最佳。结论:优化激光扫描速度,可以显著提升熔覆层的质量与综合性能;熔材中Zr元素以ZrO_(2)、ZrC以及固溶形式存在于熔覆区;马氏体间错位滑移阻力、TiC等增强相以及Zr元素固溶强化作用使显微硬度得以提升。To improve the mechanical properties of YSZ thermal insulation coating,clarify the formation process and mechanism of its structure and find the optimal laser processing parameters.The Ti/7YSZ composite coating system was prepared on TC4 surface by laser cladding with YLS-3000 fiber laser system.The macro morphology,microstructure,element distribution,phase composition and hardness distribution of Ti/7YSZ composite thermal barrier coating were characterized by optical microscope,SEM,EDS,XRD and hardness tester respectively.The results show that:the surface of the cladding layer is yellow to varying degrees at different laser scanning speeds,the microstructure of the cladding layer is characterized by"fine in the upper and lower,thick in the middle",which is mainly composed of acicularα′martensite,martensite core,residualβphase and MC carbide represented by TiC,Zr elements are enriched in the bonding zone of matrix and cladding zone.The Zr element distribution becomes more and more uneven,the martensite fragmentation in the cladding zone is intensified,and the hardness level increases and then decreases as the scanning speed increases.The cladding layer forms a metallurgical bond with the substrate at 7mm/s,and the average hardness level reaches a peak of 600 HV,which is 2.5 times of TC4 matrix,and the cladding quality is the best.Conclusions show that optimization of laser scanning speed can significantly improve the quality and comprehensive performance of cladding layer.Zr element exists in the cladding zone in the form of ZrO_(2),ZrC and solid solution.The microhardness can be enhanced by the dislocation slip resistance between martensite,strengthening phases such as TiC,and the solid solution strengthening effect of Zr element.

关 键 词：马氏体 TC4激光熔覆 显微组织 显微硬度 

分 类 号：TG174.442.1[金属学及工艺—金属表面处理] TN249[金属学及工艺—金属学]