原位掺杂纳米缓蚀微胶囊的镁合金微弧氧化涂层的制备及其双重自修复机理的研究

Traditional self-healing coatings are not capable to provide long-term protection for Mg alloys when they are utilized for aerospace equipment, since the service environment is complicated and severe. Herein, the high porosity of micro-arc oxidation (MAO) coating can be considered as natural reservoir to preserve inhibitor-containing LDH nanocontainers. Mg inhibitors are selected and then loaded into LDH nanocontainers. The aim of this project is to inertly incorporate LDH nanocontainers into MAO coating by optimizing treatment parameters during coating growth process. The good absorption ability and exchangeability of LDH can be used to provide primary protection ability. After long-term service, the loaded inhibitors will be released from the nanocontainer and mitigate corrosion by adsorbing or precipitating as a second barrier layer in the coating/Mg interface. Model of ion exchange reaction kinetics and adsorption kinetics will be designed, and the relationship between “treatment parameters—coating microstructure and morphology—concentration, distribution and incorporation mode of LDH nanocontainers—self-healing ability and corrosion resistance of the layer ”will be illuminated. Consequently, it is extremely urgent to design and fabricate double self-healing MAO coatings on Mg alloy, since this would be of great significance for Mg alloys to achieve a wider range of applications in the area of aerospace equipment.

由于航天器材服役环境极其复杂严峻，传统镁合金自修复涂层仍旧不能保障长周期安全服役性能。本项目以镁合金微弧氧化涂层天然的多孔骨架结构作为载体，将缓蚀剂嵌入水滑石纳米胶囊，通过调控氧化处理工艺参数，将纳米缓蚀微胶囊原位惰性掺杂并封装于涂层中。利用水滑石的快速吸附能力和层间阴离子可交换性，在短周期内提供第一重防护；长周期服役后，水滑石纳米胶囊所释放的高效缓蚀剂将作用于内部涂层/镁合金基体界面处，达到第二重自修复功效。通过建立水滑石离子交换反应动力学和吸附动力学模型，阐明“微弧氧化处理工艺参数—涂层微观组织形貌—水滑石含量分布及掺杂模式—涂层耐蚀性能”之间的相关性，开发订制具备双重自修复功效的“绿色智能”镁合金微弧氧化涂层。项目的开展不仅能为镁合金新型防护涂层的制备提供理论支持和技术指导，对于镁合金在航空航天领域的大规模应用也有着重要的意义。

较差的耐蚀性能一直制约了镁合金的大规模应用。本项目揭示了以十二烷基硫酸钠为代表的镁合金高效缓蚀剂的作用机制，发现缓蚀剂的极性基团在腐蚀初期可吸附在基体的阴极相上，抑制阴极析氢反应和微电偶腐蚀。腐蚀过程中，缓蚀剂通过其疏水基团吸附在腐蚀产物上，形成一层稳定、致密的腐蚀产物膜，从动力学上抑制阴极和阳极腐蚀反应。通过合成锌铝水滑石纳米胶囊作为缓蚀剂的载体，在微弧氧化成膜过程中调控工艺参数，将负载缓蚀剂的纳米胶囊原位惰性掺杂于微弧氧化涂层中，成功制备出双重自修复镁合金微弧氧化涂层。此外，系统地研究了电解液组分、浓度和电参数多因素交互作用对颗粒物的掺杂改性机制的影响，为实现水滑石纳米胶囊含量和分布的可控性提供技术指导。阐明了“微弧氧化工艺参数—涂层微观组织形貌—水滑石含量分布及掺杂模式—涂层耐蚀性能”之间的相关性。本项目按计划完成了所有研究内容，取得了预期研究成果，共发表SCI论文16篇（包括腐蚀领域知名期刊Corrosion Science上6篇），授权国内发明专利3项，在国际和国内会议做分会口头报告6次（邀请报告2次），培养博士研究生2名，硕士研究生5名（已毕业3名），1人获2018年“中国腐蚀与防护学会科学技术奖”一等奖。