热障涂层高温TGO生长和微缺陷演化的太赫兹定量无损评价机理及其可靠性研究

Thermal barrier coatings (TBCs) on turbine blade of aero-engines are the key advanced materials systems to ensure the efficient and reliable operation of the engines. During the high-temperature service of the TBCs, thermally grown oxide (TGO) layer progressively thickens. When the thickness of a TGO layer reaches micron order, microcracks will be initiated within the layer, ultimately leading to cracking, delamination and spalling of the TBCs. This greatly affects the service life and safety of the aero-engines. Traditional nondestructive testing (NDT) method is difficult to achieve high-resolution measurement of early TGO layer if the detection depth is needed to be guaranteed. In addition, the failure theory of thermal barrier coatings based on destructive testing techniques, is also needed to be improved or validated. In the project proposal, aiming to resolve the problem of high-resolution early health diagnosis of the TBCs on turbine blade of aero-engines, we propose to investigate terahertz non-destructive testing and quantitative evaluation (NDT&QE) of TGO growth and microdefect evolution. Mathematical models for TGO growth and crack propagation by using finite element method (FEM), together with a model of terahertz wave propagation in TBCs, will be built to study high-sensitivity algorithms for feature extraction of TGO at initiation stage and small defects. A terahertz system will be enhanced on its detection depth, resolution and speed as well. Under the conditions of high temperature oxidation and repeated thermal shock on TBCs, the growth of TGO, defect formation and evolution law will be deeply investigated by using the optimized terahertz system. In addition, the reliability of non-destructive testing of TBCs will be studied. It will provide a novel methodology to improve the failure theory of thermal barrier coatings. The research has importance of scientific value and guiding role in scientific evaluation and efficient usage of TBCs, and development of novel TBCs and their life prediction.

涡轮叶片热障涂层是保障航空发动机高效可靠运行的关键。在高温服役过程中，热生长氧化层（TGO）厚度逐渐增加到微米量级时内部易形成微观裂纹，导致热障涂层开裂、分层和剥落，严重影响发动机服役寿命和安全性。传统无损检测方法很难在保证检测深度前提下对早期TGO薄层进行高精度检测, 而基于破坏性检测方法建立的热障涂层失效机理有待完善。项目针对涡轮叶片热障涂层早期的高精度健康诊断难题，提出TGO生长和微缺陷演化过程的太赫兹无损检测和定量评价方法。建立TGO生长和裂纹扩展有限元模型及太赫兹波传播模型，研究萌生之初的TGO和微小缺陷高灵敏度特征提取算法。通过提高太赫兹检测深度、精度和速度，探索在高温氧化和热冲击下TGO生长、缺陷形成及其演化规律，并研究热障涂层无损检测可靠性问题，为完善热障涂层失效基础理论开辟新途径。项目研究对科学评价和高效利用热障涂层，开发新型热障涂层及其寿命预测等具有科学价值和指导作用。

涡轮叶片热障涂层是保障航空发动机高效可靠运行的关键。在高温服役过程中，热生长氧化层（TGO）厚度逐渐增加到微米量级时内部易形成微观裂纹，导致热障涂层开裂、分层和剥落，严重影响发动机服役寿命和安全性。传统无损检测方法很难在保证检测深度前提下对早期TGO薄层进行高精度检测, 而基于破坏性检测方法建立的热障涂层失效机理有待完善。项目针对涡轮叶片热障涂层早期的高精度健康诊断难题，提出了TGO生长和微缺陷演化过程的太赫兹无损检测和定量评价方法。建立了TGO生长和裂纹扩展有限元模型及太赫兹波传播模型，研究了萌生之初的TGO和微小缺陷高灵敏度特征提取算法。通过提高太赫兹检测深度、精度和速度，探索了在高温氧化和热冲击下TGO生长、缺陷形成及其演化规律，并研究了热障涂层无损检测可靠性问题，为完善热障涂层失效基础理论开辟新途径。项目研究对科学评价和高效利用热障涂层，开发新型热障涂层及其寿命预测等具有科学价值和指导作用。项目执行过程中，发表34篇论文（其中29篇SCI）和1本Spring英文专著；申请专利27项（其中美国和英国专利各1项）和8项软件著作权；获得省部级科技奖4项（其中排名第一的福建省科技进步奖一等奖和二等奖各1项）、上银优秀机械博士论文奖指导教师、卢嘉锡优秀导师奖、中国国际“互联网+”银奖指导教师、全国挑战杯二等奖指导教师等；先后入选百千万人才工程国家级人选、国家有突出贡献中青年专家、英国工程技术学会会士、国际状态监测学会会士；兼任福建省机械工程学会无损检测分会理事长、福建省力学学会副理事长等。