航空发动机叶片强韧陶瓷-金属涂层砂尘冲蚀损伤机理

Irregular sand grains may cause erosion and corrosion to the surface of the aero-engine blades which will severely affects the operability and security of helicopters. Ceramic-metal multi-layer coatings have several features, such as high strength, good fracture toughness and easy to be designed which is used as a major way to improve the anti-erosion quality of aero-engine blades through protecting the blades against several kinds of damage. However, the anti-erosion quality of coatings is closely related with the coating’s structure, its physical properties and the characteristics of the sands. The way to improve the fracture toughness has always been the key problem which has hindered the improvement of the anti-erosion quality of multi-layer coatings. The aero-engine blades of a helicopter subjected to severe sand erosion environment were taken as the samples of the research in this research. It focused on finding out the dynamic interaction between sands and ceramic-metal multi-layer coatings, and the dynamic response between coatings and the base material through a combined method of theoretical reasoning, experimenting and data analyzing. It further analyzed how ceramic-metal coatings were damaged by the combined effect of sand erosion and corrosion in order to lay the theoretical foundation for the establishment of the research system on multi-layer anti-erosion coatings. The results of this research are of great significance to the further research and development of advanced aero-engines with good quality, long life cycle and high reliability.

多尺度、无规则砂尘对直升机发动机叶片表面的侵蚀、磨损是影响直升机作战性能和安全使用的突出问题。陶瓷－金属多层涂层具有强度高、断裂韧性好和设计性强等特点，可同时抵御多种损伤模式破坏，是提高航空发动机叶片冲蚀性能的主要方法。然而，涂层的抗冲蚀性能与涂层结构、力学性能以及砂尘特性密切相关，结构强韧性一直是制约多层涂层抗冲蚀性能的关键问题。本项目以恶劣砂尘环境直升机发动机叶片为研究对象，采用理论、试验和数值研究相结合的方法，重点研究砂尘与陶瓷－金属多层涂层相互作用的动态过程以及涂层与基体的动态响应规律，深入分析磨损和冲击复合作用下陶瓷－金属涂层的损伤模式和损伤机理，为建立多层抗冲蚀涂层研究体系奠定理论基础。研究成果将对促进我国高性能、长寿命和高可靠性先进航空发动机的研究与发展具有重要意义。

压气机叶片砂尘冲蚀是影响航空发动机沙漠地带服役性能与安全可靠性的关键问题。涂层是提高压气机叶片抗砂尘冲蚀的有效措施。然而，多尺度、无规则砂尘对材料表面冲蚀损伤机理十分复杂，结构简单、性能单一的涂层无法满足防护要求。本项目以多层陶瓷－金属涂层为研究对象，采用实验、数值仿真与机理研究相结合的方法，围绕砂尘冲蚀涂层结构强韧性优化的关键基础问题－“多层涂层冲蚀动态响应规律及损伤机理”开展研究，主要内容包括：.（1）典型砂尘特性和涂层结构特性建模。采用基于图像处理的砂粒二维形貌表征方法，根据砂粒截面图像，快速的识别砂粒轮廓、提取砂粒形貌特征，从而实现砂粒形貌的定量化描述，获得典型砂尘形貌和特征，采用有限元计算与实验研究相结合的方法，基于砂尘特性，建立了陶瓷/金属多层涂层的参数化有限元模型。.（2）砂尘冲蚀陶瓷-金属多层涂层动态响应特性研究。采用ABAQUS模拟仿真的方法，分析了涂层在粒子作用下的运动过程，获得了陶瓷层的冲击动态响应。分别以涂层表面的最大拉应力最小化和为陶瓷层下表面的最大拉应力最小化优化目标对涂层结构进行优化设计，研究结果表明：涂层表面最大拉应力最小化情况下，单层涂层是最佳的选择。如果以陶瓷层下表面的最大拉应力最小化为目标，则层数数越多越好。而涂层表面的最大拉应力值则随着层间调制比的增加而先迅速下降，直至调制比大于7后，拉应力的降低幅度逐渐趋于缓慢。.（3）砂尘冲蚀陶瓷－金属多层涂层损伤机理研究。采用硬质小球重复冲击方法，定量分析了不同冲击条件下TiN/Ti涂层的损伤形貌，得到其损伤特征及其相应位置，以及涂层损伤过程。揭示了涂层冲蚀损伤机理，在重复冲击作用下，硬质层内的重复交变应力与高应力梯度是导致其产生疲劳圆周裂纹和疲劳剥落的原因，硬质层与延性层之间的高应力梯度，和延性层累积塑性应变硬化开裂是导致层间疲劳剥落的原因。.研究成果申请国家发明专利2项，发表学术论文6篇，EI检索5篇。