长寿命航空主轴承断油循环中摩擦表界面行为与抗胶合机制研究

The scuffing damage is likely to occur in the spindle bearings in aircraft engines due to the increase in the speed, loading, temperature and life of the bearings. This project focuses on the behaviors of the tribo-behaviors of M50 steel bearings and the 4050 oil system, i.e. the oil deterioration, changes of contact mechanism, heat accumulation, thermal-mechanical coupling effects, the damage behaviors of surface coatings during the periodical process of full-starved-off oil. In order to The dynamic multi-physics coupling model is built for the contact interface based on the online AE techniques, focused ion beam tests and the dynamic oil rheology. The model is used for real-time monitor of the oil lubricating conditions. The correlation between the structural properties and the failure characteristics of the surface and near surface layers is analyzed. The stress field in the contact systems is equivalently analyzed by using the ball-on-disk tests and the interface mechanism, which solves the unequivalent situation between the stresses in the nano indentation/scratch tests and the bearings. The sliding and sliding/rolling contact tests under different conditions are conducted for testing the correlation between the thermo-structural status and the scuffing behavior on the surface and interface of the tribo systems. The evaluation and prediction of the contacting characteristics and the design of the solid lubricating films could serve to the reliability guarantee for the spindle bearings in aircraft engines under extreme work conditions.

航空发动机主轴轴承的转速、载荷、温度和寿命要求日益增长，轴承面临着乏油乃至无油工况下的胶合风险。针对M50钢轴承和4050油摩擦体系在富油、乏油和无油转换与循环过程中的润滑剂劣化、接触界面润滑力学特性变化、热累积与力热耦合效应反馈、表面层及薄膜在润滑剂缺失或参与状态下损伤行为的系统研究。建立在线声发射、聚焦离子束、滑油随工况变化流变综合模型等动态响应建立接触界面多场耦合的时变模型，实现接触界面润滑状态的在线识别；摒弃传统纳米压/划痕锥形压头三维应力场与实际轴承服役界面应力场差异，采用同应力场球形接触测试与界面力学分析相结合方法，实现表界面层在复合载荷状态下的界面应力应变与失效特征关联规律的辩识；通过多层次工况滑动摩擦和滑滚试验获取摩擦过程力-热状态及其转换耦合与摩擦体系表界面胶合行为的关联规律。为航空主轴承在苛刻工况下的可靠工作提供接触界面的参数评价预测以及表面固体薄膜设计保障。

围绕航空轴承在高速高温重载、急变速工况以及断油过程摩擦界面润滑状态劣化问题，以M50轴承钢配副作为主要研究对象，理论探讨了摩擦表界面损伤形成过程中摩擦热与塑性变形热协同作用下基于表界面材料热机械物理参数和本构关系的失效判据。利用滑滚接触试验平台验证了界面失效机制以及失效发生的临界应力和滑动速度边界。基于界面失效判据的参数边界可为航空发动机主轴轴承的预防早期损伤提供参数优化的理论基础。针对断油过程中的磨损和胶合失效问题，探索了表面薄膜改性工艺方法；建立了膜基系统热弹性接触问题的半解析模型，基于镜像点法和虚功原理求解了热-弹性接触的应力和温升分布，探讨了工况参数、摩擦系数和膜基材料参数的影响；针对M50轴承钢，优选可在450°C 以上高温及循环重载下工作的氮化物涂层参数。采用表面涂层的M50轴承钢研制的全钢与混合式陶瓷球轴承在航空润滑油润滑下的接触疲劳试验表明，M50轴承钢表面氮化物涂层可在1800MPa以下应力发挥极限工况抗磨抗疲劳作用。项目关于界面失效判据和薄膜力热耦合分析方法丰富了苛刻工况轴承的极限设计方法，实践成果已直接应用于航空发动机主轴轴承设计优化以及支撑航天机构超高温轴承产品开发。