锆酸镧涂层高温结构演变及热导性能  

Structure evolution and thermal conductivity of lanthanum zirconate coating after high temperature exposure

作　　者：王衍飞[1] 江堤 王思青[1] 刘荣军[1] 韩敬 WANG Yanfei;JIANG Di;WANG Siqing;LIU Rongjun;HAN Jing(Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering,National University of Defense Technology, Changsha 410073,China)

机构地区：[1]国防科技大学空天科学学院新型陶瓷纤维及其复合材料国防科技重点实验室

出　　处：《航空材料学报》2019年第4期26-31,共6页Journal of Aeronautical Materials

基　　金：国家自然科学基金(51502342);国防科技大学科研计划项目(ZK17-03-57);湖南省自然科学基金(2018JJ1029,2019JJ50720)

摘　　要：采用固相反应法制备 La2Zr2O7原料粉体,经喷雾造粒后,采用大气等离子喷涂工艺(air plasma spray,APS)制备 La2Zr2O7涂层。重点研究 La2Zr2O7 涂层在高温长时间条件下的物相组成、微观结构以及导热性能。结果表明:La2Zr2O7涂层具有烧绿石单相结构,密度平均值为 5.24 g cm^3,相成分及密度均不随热处理时间的延长而发生明显变化;初始态涂层内部存在大量非晶态结构,能够有效阻碍声子的传递,涂层热导率可低至 0.392 W·m^-1· K^-1;经高温热处理后,非晶态结构逐渐转变为晶态结构,声子传递效率明显提高,导致涂层热导率显著上升;同时,热处理后的涂层高温热导率的回升现象明显减弱。La2Zr2O7 powders were synthesized by solid-state reaction method. After spray granulation, the La2Zr2O7 coatings were fabricated by air plasma spray technique. The effect of heat treatment time on the properties of La2Zr2O7 coatings was investigated, focusing on phase composition, microstructure evolution and thermal conductivity. The results show that a single pyrochlore phase of La2Zr2O7 coating has been successfully fabricated. And the average porosity is 11.3%. The phase composition and porosity do not change with the prolongation of heat treatment time. The thermal conductivity of the as-sprayed coating can be as low as 1 1 0.392 W ·m^-1·K^-1. A number of amorphous structures exist in the as-sprayed coating, which can effectively block the transmission of phonons. With an increase of thermal exposure time at 1300 ℃ in air, the amorphous structure is gradually transformed into crystalline structure, and the phonon transfer efficiency is obviously improved, resulting in a significant increase in the thermal conductivity of the coating. Interestingly, after heat treatment, the rebound effect of thermal conductivity at high temperature didn’t appear in this research.

关 键 词：热障涂层 大气等离子喷涂(APS) 热导率 锆酸镧(La2Zr2O7) 热处理 

分 类 号：TB332[一般工业技术—材料科学与工程] TB34