镁合金表面功能梯度薄膜界面结合机制与磨蚀协同损伤效应研究

In order to solve the key technical problems of the dynamic wear-corrosion synergy failure existing in the current magnesium alloy parts, a new method of the functional composite films system consisting of the substrate adhesion layer and the corrosion insulation layer and the middle bearing layer and the top wear-resisting layer is proposed, and functional gradient films with wear resistance and corrosion resistance are synthesized by PIIID-RFMS in this study. By studying the composition design and interface scale regulation, texture feature and mechanics properties, interfacial adhesion mechanism and wear-corrosion synergy failure behavior, the relationship among the composition, structure, load condition and the failure behavior of composite films system will be revealed, the interfacial adhesion strength evaluation mathematical model will be constructed, the stress-strain fields evolution laws existing in the films system will be calculated, and the structure design method of the functional composite films system with high adhesion strength will be proposed. In addition, the formulate of tribological properties evolution, tribological chemical reaction and solid-liquid diffusion reaction law during the dynamic wear-corrosion synergy failure course will be also proposed, the wear-electrochemical corrosion cooperative interaction and damage mechanism will be expounded combining with the distribution characteristics of the stress-strain fields. The research results will provide theoretical understanding and technique support for design and synthesis and industrial applications of the functional gradient films with high adhesion strength and long life and wear-corrosion resistance on magnesium alloy parts used in car industry and electronic communications and aerospace fields.

针对镁合金零部件工程应用中存在“动态磨蚀失效”关键技术难题，本项目提出“基体结合层/腐蚀绝缘层/中间承载层/顶部耐磨层”功能复合膜层体系设计思路，并基于PIIID-RFMS技术复合制备自润滑耐磨与耐蚀功能梯度薄膜。通过膜层成分设计与界面尺度调控、织构特征与力学特性、界面结合机制与动态磨蚀失效行为等内容研究，揭示动态承载下膜层体系失效与其成分、结构、性能及载荷条件等参数之间关系规律，构建膜层体系界面结合强度评价数学模型，预测膜层内部应力/应变场演变规律，提出高结合强度膜层体系结构设计方法；阐明动态磨蚀失效过程中薄膜摩擦性能演变、摩擦化学反应与固-液界面扩散反应规律，并基于膜层内部应力/应变场分布特征，阐述磨蚀失效过程中磨损-电化学腐蚀协同交互作用与损伤机理。本项目研究成果为汽车、通讯、航空航天等领域用镁合金部件表面高结合强度、长寿命及耐磨蚀梯度薄膜的设计制备与工程应用提供理论基础和技术支撑。

针对镁合金表面强韧化耐磨与耐蚀关键技术需求，本项目从优化涂层体系设计入手，提出功能梯度复合涂层设计理念，利用等离子体注入与沉积、射频磁控溅射和喷涂复合技术可控构筑Al/AlN/CrAlN/CrN/MoS2和AlN/CrAlN/MoS2-酚醛树脂复合涂层。项目全面解析了涂层纳米微结构、摩擦磨损与电化学腐蚀、动态承载失效行为与磨损-电化学腐蚀协同损伤效应等核心内容。研究发现：AlN层具有（002）择优取向生长，CrAlN层由Cr-Al-N固溶体组成，溅射沉积MoS2层呈非晶态结构，MoS2-酚醛树脂层具有两相复合结构，即MoS2微晶镶嵌酚醛树脂矩阵中；摩擦过程中顶部耐磨层通过在材料表面形成MoS2转移膜而赋予涂层自润滑减摩特性，但涂层耐磨寿命依赖基体承载能力，引入中间强化层是提升基体承载能力与涂层服役寿命的有效策略，但膜层电化学特性影响涂层耐蚀性能，当膜层电化学参量接近或差异较小时，涂层体系表现较好腐蚀防护效果；涂层体系动态承载失效过程中，组元膜层发生协同变形并诱发界面应力产生，膜层H/E值差异较大界面处应力值高于其他界面，高应力驱动疲劳微裂纹在强度较低膜层近界面处萌生、扩展与累积，并最终导致涂层断裂，高强韧涂层体系设计应依据膜层纳米力学参量优化匹配或梯度渐变设计，避免力学参量突变形成；动态磨蚀过程中存在强摩擦力-电化学腐蚀协同与交互作用，涂层磨蚀失效包括接触载荷下疲劳变形与断裂、涂层/基体界面的点蚀、电化学腐蚀与钝化等多层次/多区域的叠加损伤，涂层结构设计应充分考虑控制涂层变形、抑制裂纹萌生与阻隔腐蚀介质扩散等多重功能需求，在优化膜层纳米力学参量配比同时，应避免较大电化学参量梯度形成。本项目借助试验研究与理论模拟方法，深入系统阐述了功能梯度涂层材料-结构-功能一体化设计策略与寿命预测方法，为镁合金表面长寿命抗磨与耐腐蚀防护涂层的设计制备、性能优化与工程应用奠定理论基础。