潜在热障涂层材料RE3TaO7和RETa3O9陶瓷的力学与热物理性质研究

Thermal barrier coatings (TBCs) material is one of the most important materials used in gas turbine and aero engine. The current TBCs material is the 7YSZ, 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. RE3TaO7 and RETa3O9 (RE/RE`=La, Ce, Nd, Sm, Eu, Gd, Er, Yb) as one type of new TBCs is expected to exceed 1600 ℃ in our previous research. Moreover, we plan to use RE3TaO7 and RETa3O9 ceramics to replace YSZ to get lower thermal conductivity and better fracture toughness at high temperature. RE3TaO7 and RETa3O9 materials, with ceramics synthesis, phase structure, mechanical and thermal properties and stability would be investigated by computational materials science and experiments in this project. In addition, PS-PVD and EB-PVD technology are used in the experiments to fabricate the thermal barrier coatings. Moreover, 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. Summary of rare earth elements, RE 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 next generation thermal barrier coating material, the related research can provide theoretical basis for further exploration and support.

陶瓷热障涂层材料在燃气轮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，是先进燃气轮机和航空发动机中最关键的材料之一。当前服役的YSZ陶瓷热障涂层材料使用温度不能突破1200℃，难以满足更高温度的航空发动机对材料的需求。本项目拟采用具有质量较重原子的稀土钽酸盐RE3TaO7和RETa3O9陶瓷(RE/RE`=La, Ce, Nd, Sm, Eu, Gd, Er, Yb)作为新的候选材料，采用第一原理计算结合实验测试，确定稀土钽酸盐RE3TaO7和RETa3O9陶瓷的力学与热物理性质，获得稀土离子对性能影响的普遍规律；采用APS和EB-PVD等技术制备稀土钽酸盐RE3TaO7和RETa3O9陶瓷涂层，获得涂层的界面性质，揭示涂层抗氧化性能及耐腐蚀性能的机制，进而通过调控相结构获得最佳性能的新型热障涂层材料，相关研究可为进一步的探索提供理论基础与支撑。

热障涂层主要用于高超声速飞行器、运载火箭和航空发动机等大国重器的高温零部件表面提供隔热防护的作用，通常其需要具有低热导率、与基体匹配的热膨胀系数、高硬度和高断裂韧性等性能特点。当前的氧化钇稳定氧化锆（YSZ）陶瓷的工作温度低于1200℃，同时具有热导率偏高和服役寿命短等问题，已经无法满足当前工作和国防发展对热障涂层材料的需求，亟需开发新一代的低热导率、工作温度高和服役寿命长的新一代热障涂层材料。项目研究过程中开发了新一代的潜在热障涂层材料稀土钽酸盐RE3TaO7和RETa3O9，通过高温固相法制备致密的稀土钽酸盐陶瓷块体材料，对其热导率、热容、热膨胀系数、高温相稳定性、硬度、断裂韧性和杨氏模量等热学和力学性质进行研究，获得了具有低热导率（1.0 W/m/K）、热膨胀系数可控（4-12*10-6 K-1）、高硬度（10 GPa）、高断裂韧性（1-3 MPa.m1/2）和1500℃内无相变的新型稀土钽酸盐热障涂层材料。同时通过等价稀土离子置换和合金化效应的方式对RE3TaO7的热物理性能进行进一步优化，获得具有与合金基体热膨胀系数匹配、热导率达到理论极限值的新型热障涂层材料，为开发新一代的低热导、高热膨胀系数和无高温相热障涂层材料提供参考。