石墨烯/Nd3+/Eu3+共掺杂温敏热障涂层的制备及光响应温度行为研究

The internal temperature of thermal barrier coating is unable to get feedback in real-time and to control, which easily accelerates oxidation and leads to premature failure. In response to these key issues, graphene co-doped Nd3+ and Eu3+ rare earth ions (graphene/Nd3+/Eu3+) thermal barrier coating, which is temperature sensitive, will be prepared by liquid plasma spraying in this project. The internal temperature variations of coating can be monitored in real time by using the mapping relationship between the luminescent property and the temperature. First, the composition ratio between graphene and Nd3+/Eu3+ will be adjusted and optimized to enhance its luminescence. Then, to achieve the luminescent intensity in the full range of coating thickness with high sensitive response to varying temperature, a multilayered and graded structure with different graphene/Nd3+/Eu3+ ratio will be designed. Finally, the evaluation of service health status and the prediction of remaining life of the thermal barrier coating will be realized by establishing the mapping relationship between luminescent intensity and temperature, as well as the correlation between luminous intensity attenuation characteristic and service time in high temperature. This project will lay important theoretical foundations for predicting coating failure in view of light response temperature characteristics.

针对热障涂层服役过程中内部温度无法实时反馈和控制，容易造成涂层氧化加速而过早失效的关键科学问题，本项目提出采用液料等离子喷涂技术制备石墨烯/Nd3+/Eu3+稀土离子共掺杂的温敏热障涂层，利用稀土元素发光性能与温度的映射关系，可实时监控涂层内部温度的变化趋势。首先通过石墨烯对Nd3+/Eu3+进行改性及成分调控，实现增强其发光强度的目的，其次通过各层掺杂不同含量石墨烯/Nd3+/Eu3+设计多层梯度结构，实现涂层厚度全范围内的发光强度随温度变化高灵敏响应性，最终通过研究发光强度与温度的映射关系、发光强度衰减特性与高温服役时间的关联性，实现有效评估热障涂层服役健康状况和准确预测其剩余寿命的目的，为温敏热障涂层基于光响应温度特性预警涂层失效奠定理论基础。

热障涂层（TBCs）因出色的隔热、抗氧化等性能成为高性能燃气轮机中不可或缺的一部分，氧化钇稳定氧化锆（YSZ）是目前应用最成熟的TBCs材料。在TBCs的服役过程中，热应力的累积会在涂层中产生裂纹造成涂层过早失效，失去防护作用。本项目在YSZ基热障涂层中添加晶须以期提高涂层的断裂韧性，从而延长其服役寿命；在涂层中掺杂稀土氧化物，利用稀土的发光性能监测涂层的服役状态，并研究了涂层组织和其他性能的变化。研究结果表明：.1.在YSZ涂层中添加AlBOw涂层的抗热震性能较YSZ涂层稍下降。添加BNw涂层的抗热震性能比YSZ涂层提高了62.2%，晶须通过裂纹偏转、晶须拔出和晶须桥接等机制抑制了裂纹的扩展，延长了涂层的寿命。.2.稀土氧化物Eu2O3和Nd2O3的掺杂对YSZ基涂层的影响规律相同。稀土掺杂涂层的相结构由t´相组成。随着稀土掺杂量的增加，涂层的孔隙率降低、显微硬度和断裂韧性得到提高，涂层的结合强度先升高后降低。涂层的发光强度随着稀土氧化物掺杂量的增加而增强；在经历热震实验失效后，涂层的发光强度均发生一定程度的降低。.3. BNw改性Nd2O3掺杂YSZ涂层中，30vol.%晶须含量的涂层较20vol.%含量涂层的孔隙率提高了47.9%。孔隙率的提高降低了涂层内片层间的结合面积，断裂韧性和抗热震性能提高了8.5%和9.9%。晶须含量为30vol.%时，得到了具有更优的综合性能的YSZ基热障涂层。.其科学意义体现在揭示了智能自敏涂层荧光响应服役温度的数字化定量表征新原理，通过本项目研究搭建释放热量的环境平台，可原位采集耦合温度与光电信号采集的检测系统，监控高低温交变等激发荧光光谱、发光强度的变化历程，建立光电倍增处理发光强度与荧光分光计量，荧光光谱的多通道光子计数统计之间的量化表征关系模型，解决了针对稀土离子荧光信号与涂层应力/温度等服役性能的定量评估难题。