严酷海洋环境稀土系高强镁合金防护涂层下界面腐蚀电化学行为与失效机制

The future demand for light and efficient of military equipment will accelerate the application of develop magnesium alloy. However, the weak corrosion resistance of magnesium alloy is always limiting its application, especially the basic problems for corrosion and protection technology of rare earth high strength magnesium alloy is urgent need in the marine environment. In this research, combine outdoor exposure with indoor-accelerated corrosion tests and use a variety of testing methods, the basic problems of the organic coating/the magnesium interface and the galvanic corrosion behavior of the magnesium alloy in severe marine environment are deeply and systematically studied from the department of rare earth high strength magnesium alloy galvanic corrosion and failure of coating. For in-depth knowledge and understanding of the corrosion mechanism and under coating failure of magnesium in severe marine environment, the galvanic corrosion behavior of rare earth high strength magnesium alloy in severe marine environment, corrosion electrochemical behavior at the interface under protective coating and the effect of environmental factor on the coating stability and general performance need to study first. That will also provide a theoretical basis for protective coating design and use. Based on the results of outdoor exposure test and laboratory research, the load spectrum for protective coating of rare earth high strength magnesium alloy in severe marine environment will be established, which will provide the design basis and technical support for the development of protective coating and the prediction of service life.

未来军事装备对轻质高效的需求将加大镁合金的用量。但目前镁合金弱防腐性能限制了其应用，特别是在海洋环境下针对稀土系高强镁合金的腐蚀与防护技术的相关基础问题亟待解决。本课题结合实验室内外环境利用多种测试手段，从稀土系高强镁合金电偶腐蚀与涂层失效入手，针对严酷海洋下有机涂层与金属界面的基础性问题与镁合金电偶腐蚀行为与机理进行深入、全面的自主研究。从稀土系高强镁合金在严酷海洋环境下的电偶腐蚀行为、防护涂层下界面腐蚀电化学行为、影响涂层失效关键因素等方面，深入探讨严酷海洋环境下稀土系高强镁合金的腐蚀行为机理与涂层下界面失效机制，为镁合金用防护涂层设计、制备提供理论依据。并基于室外暴晒试验结果与实验室内研究，建立严酷海洋环境下针对稀土系高强镁合金防护涂层的考核载荷谱，为防护涂层的开发与服役寿命预测提供设计依据与技术支持。

近年来，军事装备等高端装备对轻质高效的需求极大的加大了镁合金的应用需求。但是镁合金的弱腐蚀性能，特别是在海洋环境下的腐蚀隐患极大的危害装备的可靠性。基于此，本课题针对严酷海洋环境稀土系高强镁合金防护涂层下界面腐蚀电化学行为与失效机制开展研究工作。首先在我国南海地区的西沙环境试验站对两种稀土系高强镁合金和不同偶接条件下的电偶腐蚀试样进行实地暴晒试验研究，获得了稀土系高强镁合金在南海海洋环境下的腐蚀动力学规律和热力学特征。并在我国不同典型海洋环境（西沙、青岛、舟山）对典型环氧防腐涂层进行实地暴晒试验研究，获得了环氧防腐涂层在海洋环境下的腐蚀退化规律和环境关键因素。随后在实验室内基于室外试验结果分析稀土系高强镁合金在严酷海洋环境下的腐蚀行为与机理研究，获得了富稀土第二相对稀土系高强镁合金腐蚀的影响机制。并基于电化学等手段结合有限元分析建立了稀土系高强镁合金电偶腐蚀评价体系研究，分析了偶对材料等因素对稀土系高强镁合金在海洋环境下的腐蚀加速作用规律。在以上基础上利用基于实验室评价加速体系进行了稀土系高强镁合金防护涂层失效研究，获得了稀土系高强镁合金表面多功能防护涂层退化失效与界面腐蚀萌生发展规律。最后进行了镁合金防护优化研究：改善镁合金电偶腐蚀防护研究、利用3D打印技术结合高熵合金在镁合金表面制备耐磨防腐多功能防护涂层体系。本项目的成果有望为面向海洋环境的轻质化装备提供设计依据与考核评价方法。