镁合金表面微胶囊型缓蚀-自愈合防腐涂层的制备及其自修复机理研究

Currently, it is an increasing interesting to improve the corrosion protection of organic coating by endowing with self-repairing. The existing methods of self-repairing can be divided into two categories: corrosion inhibition of metal and self-healing of coating defects. However, it is difficult to achieve better self-repairing effect on the surface of magnesium alloy. The high activity of magnesium alloy makes it difficult to achieve lasting repair for it by single corrosion inhibition. The cathode is a hydrogenation reaction, which is not conducive to the self-healing of coating by forming membrane in the defect. In view of this, the self-repairing properties of organic coating on the surface of magnesium alloy were improved by combined the corrosion inhibition of metal and self-healing of the organic coating. The study is based on microencapsulation technology. It is proposed to use polyaniline as the cyst wall, which can inhibit the corrosion of magnesium alloy. At the same time, its inhibition of hydrogenation reaction is beneficial to the self-healing of the capsule core. It is proposed to use thermoplastic acrylic resin as the core, which is beneficial to the corrosion protection of the cyst wall by effective shielding corrosive ion by the outflow and solidified into film. The coating achieves better self-repairing performance by synergy between corrosion inhibition of metal and self-healing of coating. The correlation between microcapsule material and self-healing properties are established, and the synergistic mechanism and self-healing mechanism of are discussed.

通过赋予有机涂层自修复性以提高其防护作用是近些年研究的热点。已有的外援型自修复的方法可分为对基体的缓蚀和在缺陷处成膜使涂层自愈合两大类。但目前在镁合金表面很难实现较好的自修复效果。一方面是因为镁合金活性较高，单独的缓蚀作用很难达到持久修复，另一方面因为阴极是析氢反应，不利于通过在缺陷处成膜实现自愈合修复。针对于此，本研究拟将缓蚀、自愈合两种自修复方式有效结合，利用优势互补，通过双重作用来提高镁合金表面有机涂层的自修复性能。在研究中，以微胶囊技术为基础，选用对镁合金有腐蚀抑制作用的聚苯胺作为囊壁，实现在缓蚀的同时抑制析氢反应，利于囊芯的成膜自愈合；选用热塑性丙烯酸树脂作为囊芯，实现流出及固化成膜后有效屏蔽侵蚀性离子，利于囊壁的缓蚀，通过协同作用使涂层达到较好的自修复性。通过研究建立微胶囊材料与自修复性能的相关性，探讨缓蚀、自愈合双重自修复协同作用机制及自修复机理。

镁合金以质轻、比强度等众多优点成为制造业轻量化发展的首选材料，但较差的耐蚀性又致使其应用严重受限。传统的有机涂层在制备或使用过程中出现的局部缺陷或损伤大大降低了涂层防护效果和使用寿命，达不到对镁合金理想的防护效果。通过赋予有机涂层自修复性以提高其防护作用将是有效的解决方法之一。. 本研究采用微胶囊技术实现涂层自修复。根据镁合金的腐蚀特点，选用对镁合金有腐蚀抑制作用的聚苯胺作为囊壁，实现在缓蚀的同时抑制析氢反应，利于囊芯的成膜自愈合；选用热塑性丙烯酸树脂作为囊芯，实现流出及固化成膜后有效屏蔽侵蚀性离子，利于囊壁的缓蚀，通过协同作用使涂层达到较好的防腐自修复性能。. 项目首先合成了热塑性丙烯酸树脂，并可实现单组份6s固化，直接添加在环氧树脂中，涂层的耐冲击性能提高5cm、附着力提高约2MPa，接触角增加24°。其次通过乳化剂的筛选以及聚合工艺优化，实现了以聚苯胺为囊壁，丙烯酸树脂为囊芯的微胶囊制备，工艺稳定。最后将合成的微胶囊添加在环氧树脂中，在镁合金表面制备涂层。研究发现涂层缺陷处微胶囊破裂后丙烯酸树脂流出固化，实现涂层的自愈合功能。同时微胶囊的添加提高了环氧涂层的附着力、疏水性能以及涂层的防护性能。