铁弹性RETaO4超高温热障涂层成分设计与性质优化

Thermal barrier coatings (TBCs) material is one of the most important materials used in gas turbine. The current TBCs material is the YSZ, but it has problems at the temperature exceed 1200 ℃ due to its phase transformation. In order to increase the operated temperature of TBCs, and new materials of TBCs are required urgently. YTaO4 as one type of TBCs is expected to exceed 1600 ℃ in my previous research. Moreover, we plan to use RETaO4 ceramics to replace YTaO4 to get lower thermal conductivity and better fracture toughness at high temperature. Rare earth tantalate (RETaO4) materials, with ceramics synthesis, phase structure, mechanical and thermal properties and stability would be investigated by computational materials science and experiments in this project. Using the first principle calculation combined other simulated methods; the mechanisms of phase transformation and reveal influence the stability of the phase are showed from the electronic - atomic level. For mixed stabilizers oxides in solid solution by calculating the density, location, nature in combination with experimental method to clarify the impact mechanism. Using the plasma technology to fabricate the RETaO4 coating, we plan to measure the related properties of these type materials. Summary of rare earth elements, Me elements on the influence of the intrinsic material properties, and then through the design doping elements and regulating the phase structure and get the best performance of new thermal barrier coating material.

热障涂层在航空发动机使用中不仅能达到抗腐蚀、提高工作温度的目的，还可以减少燃油消耗，延长发动机使用寿命等，目前使用的热障涂层材料由于材料本征性质限制很难突破1200℃，难以满足更高温度发动机对材料的需求。基于铁弹增韧的RETaO4前期研究表明有望作为1600℃热障涂层材料，通过改进其涂层制备工艺，相比YSZ综合降温梯度达200-500℃，但其高温稳定性尚需进一步优化，材料在不同温度下的热传输机制尚不明确，需要从电子-原子尺度进一步探讨其降温机理；本研究将优化设计稳定剂及稀土钽酸盐的成分、改变合成工艺来调控组织结构，最终优化其高温热学-力学性质，同时将用第一原理计算在电子-原子层次上探索稳定剂对铁弹相变机制的影响，采用等离子喷涂等技术制备系列RETaO4涂层并模拟其服役条件，进一步阐明RETaO4热障涂层超高温应用中热循环寿命延长的科学本质，获得其在1600℃应用的降温机理。

寻找新一代的耐高温、高隔热、长寿命陶瓷热障涂层材料并实现其应用是航空发动机、燃气轮机和高超声速飞行器等国之重器获得跨越式发展的关键，面对上述装备中高温合金零件的热防护需求，我们通过实验测试和第一性原理高通量筛选的方式开发新型的铁弹性稀土钽酸盐RETaO4陶瓷。研究过程中利用第一性原理计算建立了RETaO4陶瓷的成分-组织结构-力学/热学性质的关联模型，从原子位移、晶格振动、电荷转移、化学键结合强度和声子谱等角度深入分析稀土钽酸盐陶瓷的热物理性能，研究不同类型的稀土元素组成的RETaO4陶瓷材料的热传输机制，获得其低热导机理。通过高温固相法和放点等离子烧结制备致密的RETaO4陶瓷块体，对其晶体结构、显微组织和热-力学性质进行研究，并与第一性原理计算结果进行对比，筛选得到性能最优的稀土钽酸盐陶瓷。使用大气等离子喷涂（APS）的方式制备涂层材料，并通过喷涂工艺参数的优化实现涂层显微组织和服役性能的调控使其符合不同服役环境的需求。在1600℃类真是工作环境中考核RETaO4陶瓷涂层的成分-组织结构-力学/热学性能的变化规律，并探索了在高温环境下RETaO4陶瓷的抗烧结和抗CMAS腐蚀机制，为开发新一代的耐高温、高隔热、长寿命热障涂层奠定材料和技术基础。