基于镁合金氧化膜的缓蚀剂负载型LDHs膜层的生长及微区修复行为

Layered double hydroxides (LDHs) film is a novel and excellent anticorrosion film on the surface of metals, which is used as nano-containers for loading and releasing inhibitors. At present, to fabricate LDHs film from anodic oxide film has been a novel method to gain a composite protective film. However, a lot of the key issues, such as the growth mechanism of LDHs film formed on anodized magnesium alloy, the influence of the loaded-release process of the inhibitor anions on the structure and self-healing ability of LDHs film are still not resolved. These above limit the further application of LDHs film on magnesium alloys. Therefore, this research fabricates LDHs film by conversion of anodic oxide film on magnesium alloy by using in-situ growth technology. The anodic oxide film could be sealed by the growth of LDHs film and LDHs film could bring the self-healing ability at the same time. The influences of morphology and composition of anodic oxide film on LDHs film grain orientation growth are investigated. Further, the effects of reaction conditions on the growth of LDHs film are studied. The dissolving behavior of anodic oxide film and the growth behavior of the LDHs self-healing film are both studied. The loaded-release process of the inhibitor anions is discussed. The influence of inhibitor anions on the self-healing behavior of inhibitor-loaded LDHs film is analyzed. The self-healing mechanism of the composite film is proposed and the active protection and intelligent control of magnesium alloy come true. A good scientific basis for the fabrication technology and engineering applications of the self-healing LDHs film is established.

层状双羟基复合金属氧化物（LDHs）膜层是一种自身能够大量装载并释放缓蚀剂的“纳米容器”薄膜。但作为镁合金表面防护材料而言，该研究还处于起步阶段，很多关键问题如LDHs膜层生长机制、缓蚀剂负载-释放行为对LDHs膜层结构以及自修复能力的影响等均尚未解决，限制了LDHs膜层的应用。因此，本项目利用镁合金氧化膜转化制备LDHs膜层，实现氧化膜封闭与自修复能力一体化，分析反应条件以及氧化膜形貌、成分等对LDHs膜层生长的影响规律，研究氧化膜的溶解及LDHs膜层结晶生长过程，建立基于镁合金氧化膜的LDHs膜层的生长机制。通过研究缓蚀剂的负载和释放行为，研究缓蚀剂类型、浓度对负载后LDHs膜层结构的影响机制，探讨微区环境中缓蚀剂阴离子对于LDHs膜层的自修复行为的影响，建立LDHs膜层的自修复机制，从而实现对镁合金材料的主动防护和智能控制，为LDHs自修复膜层制备技术及工程化应用奠定理论基础。

层状双羟基复合金属氧化物（LDHs）膜层是一种自身能够大量装载并释放缓蚀剂的“纳米容器”薄膜，作为镁合金表面防护材料处于初始研究阶段。镁合金表面氧化膜上直接生长LDHs膜层，不仅可封闭氧化膜孔洞对氯离子的侵蚀起物理屏蔽作用，而且可存储和释放缓蚀剂离子，具备自修复能力。然而，很多关键问题如LDHs膜层生长机制、缓蚀剂负载-释放行为对LDHs膜层结构以及自修复能力的影响等均尚未解决。因此，研究镁合金表面氧化膜的缓蚀剂负载型LDHs膜层的生长及微区修复行为，实现氧化膜封闭与自修复能力一体化，具有一定的工程和科学意义。.本项目主要从基于氧化膜的 LDHs 膜层的生长机制，缓蚀剂负载对 LDHs 膜层的影响规律及负载行为，负载缓蚀剂型 LDHs 膜层微区自修复机理方面展开研究。结果表明：（1）直接利用AZ31镁合金直流阳极氧化膜中成分可原位生长LDHs膜层。与MgFe-LDHs、MgCr-LDHs膜层相比，MgAl-LDHs纳米片排布更加紧密，对阳极氧化膜层的封闭作用更加有效，耐腐蚀性最优。（2）生长溶液pH值10.72~11.72，生长温度125℃-135℃，原位生长时间约12 h，可得到结构完整、结晶度较高、耐蚀性较好的LDHs膜层。（3）直流阳极氧化膜转化生长的MgAl-LDHs膜层会经历三个阶段：快速发展期、稳定期和二次发展期。镁合金基体和阳极氧化膜的水合溶解为LDHs封闭膜层的生长提供了离子来源。（4）沸水封闭形成的无定型的Mg(OH)2聚集，可以作为后续LDHs纳米片的形核点，有利于后续LDHs膜层的生长。（5）缓蚀剂的负载使表面膜层更加致密，负载过程中的离子交换使LDHs纳米片破碎，后续可再结晶形成耐蚀性优异结构更稳定的LDHs膜层。（6）经Ce和LDHs膜层封闭处理的PEO试样再负载植酸PA，复合膜层孔隙率最低，在人为划痕处可以有效形成自修复层，表现出较强的自愈能力。（7）LDHs膜层通过负载Al2O3纳米颗粒或者脂肪酸和全氟硅烷负载修饰后，可实现膜层的耐摩擦或超疏水功能化。本项目共发表SCI论文13篇，研究成果可应用于镁合金材料的主动防护和智能控制，为LDHs自修复膜层制备技术及工程化应用奠定理论基础