铁弹性稀土钽酸盐RETaO4陶瓷的热物理性质研究进展

Thermophysical properties research progress of ferroelastic RETaO4 ceramics

工作温度是决定航空发动机、燃气轮机和高超声速飞行器发动机等大国重器的燃油利用效率和能量转换效率的关键因素。热障涂层(Thermal Barrier Coatings,TBCs)材料主要应用于高温合金零部件表面隔热降温,以提高合金零部件的工作温度。当前使用的热障涂层材料氧化钇稳定氧化锆(Yttria Stabilized Zirconia,YSZ)存在热导率高、热膨胀系数失配和工作温度低等问题,无法满足应用需求,亟需开发新一代低热导、高工作温度和长寿命的热障涂层材料。稀土锆酸盐、稀土磷酸盐、稀土硅酸盐、稀土铝酸盐和稀土铈酸盐等陶瓷材料存在断裂韧性不足、热膨胀系数低和高温相稳定性差等问题,无法取代YSZ成为新一代超高温热障涂层材料。铁弹性稀土钽酸盐RETaO(RE代表稀土元素)陶瓷具有独特的铁弹性相变增韧、低热导率、高热膨胀系数和低杨氏模量等特点,被作为下一代超高温热障涂层材料进行了广泛研究。本文总结了此类稀土钽酸盐陶瓷在热学、力学和结构等方面的研究进展,主要包括晶体结构、微观组织以及力学(硬度、模量和声速)和热学(热导率、热膨胀系数和高温相稳定性)性质等,探讨其作为下一代超高温热障涂层材料的可能性,为未来研究提供参考。

Working temperature is essential for the gas efficiency and energy conversion efficiency of multifarious aero engines, gas turbines, and hypersonic vehicle engines. Thermal barrier coatings( TBCs) are used in the high-temperature alloy components of aforementioned machines to provide thermal insulation and increase their working temperature. The most applied TBC is yttria stabilized zirconia( YSZ), but it can no longer meet the demands of current industry due to its high thermal conductivity, mismatching thermal expansion coefficients(TECs), and insufficient working temperature. It is urgent for scholars to investigate the nextgeneration TBC materials having low thermal conductivity, long lifetime, and high working temperature. The low fracture toughness, low TECs, weak high-temperature phase stability, and other weaknesses inhibit REZrO, REPO, RESiO, RECeO, and RE– Al– O oxides from being applied as TBCs. Ferroelastic rare earth tantalates(RETaO) are considered as the nextgeneration TBCs with ultra-high working temperature based on their unique ferroelastic toughening, low thermal conductivity, high TECs, and low Young’s modulus. This paper reviews the thermophysical properties of RETaOceramics, including their crystal structures,microstructures, and mechanical/thermal properties( hardness, acoustic velocity, modulus,thermal conductivity, TECs, phase stability, and so on). It is believed that RETaOceramics are candidate TBCs with high working temperature, and this paper provides scholars with some suggestions and future investigation directions on these series ceramics.