(Sm_(0.2)Gd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))_(3)TaO_(7)高熵陶瓷的制备及热物理性能

Preparation and Thermophysical Properties of(Sm0.2Gd0.2Dy0.2Y0.2Yb0.2)3TaO7 High-entropy Ceramic

寻求具有良好热物理性能的新型陶瓷材料是热障涂层领域的研究热点之一。本研究采用固相反应法制备了(Sm_(0.2)Gd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))_(3)TaO_(7)高熵陶瓷材料,对其晶体结构、显微组织、元素分布、结构稳定性和热物理性能进行了研究。结果表明:制备的高熵陶瓷具有单一的缺陷萤石结构,元素分布均匀,晶粒尺寸在0.2~3μm之间。经高温循环热处理后依然保持单一的萤石结构,表现出良好的高温结构稳定性。25~800℃范围内热导率为0.72~0.74 W/(m×K),远低于7YSZ,1200℃下的热膨胀系数约为5.6×10^(-6)K^(-1),低于热障涂层(TBCs)对表面陶瓷层材料的要求,但与环境障涂层(EBCs)硅基陶瓷基体的热膨胀系数((3.4~5.5)×10^(-6)K^(-1))接近。

Developing novel ceramic materials with excellent thermophysical properties is one of the hotspots in the field of thermal barrier coatings.The(Sm_(0.2)Gd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))_(3)TaO_(7)high-entropy ceramic was fabricated via high-temperature solid-state reaction.The crystal structure,microstructure,phase stability and thermophysical properties were investigated.Results indicate that(Sm_(0.2)Gd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))_(3)TaO_(7)high-entropy ceramic has single defective fluorite structure,its elements are homogenously distributed,its grain size ranges from 0.2 to 3μm.After high-temperature thermal cycling,the sample still remains single fluorite structure,showing excelleent phase stability at high temperature.Thermal conductivity lies in the range of 0.72-0.74 W/(m•K),lower than that of 7YSZ.Thermal expansion coefficient at 1200℃is 5.6×10^(-6)K^(-1),lower than requirement of thermal barrier coatings(TBCs)for surface ceramic layer.However,its thermal expansion coefficient is close to that of the silicon-based ceramics substrate of environmental barrier coatings(EBCs)((3.4-5.5)×10^(-6)K^(-1)).