等离子喷涂双相复合结构顶层热障涂层的研究

热障涂层 (TBCs) 是燃气轮机等设备的高温部件上不可缺少的防护技术。 La2Zr2O7 是最具潜力的顶层材料，但其韧性差等问题限制了其应用。 本研究采用双相复合陶瓷技术对 La2Zr2O7 进行改性， 以 LaPO4 与 La2Zr2O7 的双相复合材料为热障涂层顶层材料。 采用机械混合和喷雾造粒技术制备双相陶瓷材料， 利用等离子喷涂的方法制备双相陶瓷顶层。 通过热循环和冲蚀实验检测双相复合涂层的性能。 利用 X 射线衍射仪 (XRD) 检测涂层的相结构，利用扫描电镜(SEM)检测涂层的表面和剖面形貌。结果表明， 双相复合结构涂层表面微细裂纹增多， 粗大裂纹减少，裂纹会产生曲折和分叉。 LaPO4 的加入提高了双相陶瓷材料的韧性和断裂强度， 和单相 La2Zr2O7 涂层相比， 双相陶瓷涂层在冲蚀过程中失重较少。

Investigation on Thermal Barrier Coatingswith Double Phases Composite Structure Top Coat by Plasma Spray

Thermal barrier coatings (TBCs) is the key protecting technology on high temperature component. ThoughLa2Zr2O7 is the promising candidate material of top coat, the poor toughness of La2Zr2O7 limits its application. In thisstudy LaPO4/La2Zr2O7 double phases composite ceramic material is used as top coat material, which is employed toimprove the properties of La2Zr2O7. Thermal barrier coatings with LaPO4/La2Zr2O7 double phases composite ceramictop coat are prepared by plasma spray. Thermal cycling test and erosion test are used to measure the properties of TBCs.X-ray diffraction(XRD) is employed to characterize phases of coating. Scanning electron microscope(SEM) is used tocheck the surface and cross section morphologies of coatings. The results show that there are a lot of micro-cracks onthe double phases composite ceramic top coat surface, which results in the flection and forking of crack. The addition ofLaPO4 can improve the toughness and breaking strength of double phases composite ceramic material. Compared withLa2Zr2O7, TBCs with double phases composite ceramic material have less weight loss during erosion test.