等离子喷涂Gd2Zr2O7-SrZrO3复合陶瓷涂层组织结构和性能的研究

Study on Microstructure and Properties of Plasma Sprayed Gd2Zr2O7-SrZrO3 Composite Ceramic Coatings

摘要:

通过固相反应法合成了Gd₂Zr₂O₇-SrZrO₃(GZSZ, Gd₂Zr₂O₇:SrZrO₃=7:3)复合陶瓷粉末,并采用喷雾造粒法和大气等离子喷涂法分别制备了适合等离子喷涂使用的相应喷涂粉末及涂层。通过X-射线衍射、扫描电子显微镜对粉末和涂层的相组成、显微结构进行分析。借助激光热导仪、高温热膨胀仪对涂层的热扩散系数和热膨胀系数、烧结系数进行了表征。制备的GZSZ复合陶瓷粉末和涂层都由Gd₂Zr₂O₇和SrZrO₃两相组成,粉末中的Gd₂Zr₂O₇为烧绿石结构,而涂层中的Gd₂Zr₂O₇为萤石结构,SrZrO₃都为钙钛矿结构。制备态GZSZ涂层的孔隙率为~14%。GZSZ涂层1400℃热处理5 h后的热膨胀系数为9.8~11.2×10^_-6 K^_-1。制备态GZSZ涂层的热导率为~0.8 W?m^_-1?K^_-1,与制备态SrZrO₃涂层的热导率~1.0 W?m^_-1?K^_-1相比降低~20%。1400℃热处理360 h后GZSZ涂层的热导率增加到~1.5 W?m^_-1?K^_-1。研究结果表明,GZSZ涂层是一种很有前景的复合陶瓷热障涂层材料。

Abstract:

Gd₂Zr₂O₇-SrZrO₃ (GZSZ, Gd₂Zr₂O₇:SrZrO₃=7:3) composite ceramic powder was synthesized by solid state reaction. Spray drying and atmospheric plasma spray (APS) method were used to prepare corresponding spray powders and coatings, respectively. The phase compositions and microstructures of the spray dried powders and APS coatings were characterized by X-ray diffraction and scanning electron microscopy. The thermal diffusivity, thermal expansion coefficient and sintering coefficient of the coatings were characterized by a laser flash method and a high-temperature dilatometer. Both GZSZ composite powders and coatings are composed of Gd₂Zr₂O₇ and SrZrO₃. The Gd₂Zr₂O₇ powder has a pyrochlore structure, while the Gd₂Zr₂O₇ coating has a fluorite structure. And both the SrZrO₃ powders and coatings have a perovskite structure. The porosity of the coating is ~14%, and its thermal expansion coefficient after heat treatment at 1400℃ for 5 h is 9.8~11.2×10^_-6 K^_-1. The thermal conductivity of the as-sprayed GZSZ coating is ~0.8 W?m^_-1?K^_-1, which is ~20% lower than that of the SrZrO₃ coating (~1.0 W?m^_-1?K^_-1). And the thermal conductivity of the GZSZ coating increases to ~1.5 W?m^_-1?K^_-1 after heat treatment at 1400℃ for 360 h. The results showed that the GZSZ coating is a promising thermal barrier coating material.