基于MgO膜结构(Si:N)-DLC纳米复合膜层的界面结合机制及其性能研究

With the urgent needs of the aviation high-tech fields and transportation industry, design and fabrication of nano-composite films onto magnesium alloys with excellent corrosion resistance and anti-friction performance are proposed in this study. Using micro-arc oxidation (MAO) technique, a MgO coating will be prepared, which is followed by a (Si:N)-DLC nano-composite film on the top by PVD technique. Effects of the microstructure on the mechanical property and interfacial adhesion strength between the substrate and thin film will be investigated, and the adhesion mechanism of the nano-composite film can be clarified Furthermore, the relation between the characterization factors and microstructure will be illuminated during the process of wear and corrosion. The failure mechanism of the nano-composite films will be studied by the micro-analysis of the destroyed region These work could enrich the technical method to prepare DLC film on magnesium alloy, expand the application of magnesium alloys.,and further can be introduced as a guidance in the surface treatment of aluminium or titanium alloy.

针对航空高技术领域与交通等行业对镁合金的迫切需求，提出镁基表面兼具优异抗腐耐磨性能的全新结构纳米复合膜层制备方法。选用微弧氧化工艺在镁基表面构筑MgO膜结构过渡组织，以PVD为制备技术手段在其表面沉积Si、N共掺杂类金刚石（DLC）膜，获得MgO/(Si:N)-DLC纳米复合膜层；分析新设计纳米复合膜层的微结构变化对膜基系统力学性能与界面结构特征的影响规律，揭示其界面结合机制；系统研究上述复合膜层在摩擦磨损或腐蚀过程中表征参量与其微结构演变的相关性，阐明其对改善镁基体抗腐耐磨性能的作用机制；围绕此类纳米复合膜层在摩擦磨损或腐蚀过程中破坏区域的微观分析，揭示其失效机制。上述研究结果可丰富"软基体"材料表面制备高硬度DLC膜的技术手段，有助于扩展镁合金的应用空间，其研究结论也可推广至铝、钛等其它轻合金表面改性领域。

本项目在镁合金表面制备出(Si:N)-DLC/MAO纳米复合膜层，并通过对其截面的微观分析及膜基结合力测定，阐明了膜基结合机制；系统研究了气体流量配比、衬底偏压等参数对复合膜层各项性能的影响规律，并进一步揭示了其腐蚀或磨损失效的内在机制。结果显示，表层(Si:N)-DLC中通包含Si3N4结构，复合膜层表面仍具有多孔特征；随C2H2 : N2 的流量比减少或衬底负偏压增加，表层(Si:N)-DLC膜的石墨化趋势增强，sp2/sp3比值增大，其中在C2H2 : N2 的流量比为10sccm：5sccm时，复合膜层具有最优的耐磨损性能与抗腐蚀性能，偏压为-50V时，膜基体系的摩擦系数为0.18，且整个过程中摩擦系数波动很小，表现出优异的抗磨损性能。(Si:N)-DLC/MAO纳米复合膜层的结合力受MAO层与基体的结合力制约，表层DLC膜与MAO层形成机械咬合方式，并未发现化学键结合。