基于负反馈调控电催化氧转化机制的自愈合涂层防腐蚀机理研究

Self-healing coatings have displayed outstanding advantages in corrosion protection of metals.However, their low response speeds result in the decrease of protection efficiency of the coating. In this project, based on previous study on corrosion protection system, oxygen traps, namely galvanic corrosion cells that consisted of sacrificial anodes and electrocatalysts with high catalytic activity for oxygen reduction reaction, are introduced into the coating to build a self-healing corrosion protection system according to the rule of feedback controlled electro-catalytic conversion of oxygen.When the coating is subjected to defects or accidental damage,the electrolyte carrying oxygen diffuses into the defect triggering the oxygen conversion reaction of oxygen trap. Meanwhile, the oxygen adsorption corrosion of sacrificial anode is accelerated under the catalytic effect of electrocatalyst.Subsequently, the chemical barrier, namely oxygen depleted region, tends to be formed in the coating due to the constant conversion of oxygen and then inhibits the further diffusion of oxygen into the coating, thus conferring the real-time response and self-healing protection functions on the coating. This project is aimed at building a real-time response corrosion protection theory of coating based on the trigger and enhancement actions of negative feedback. Meanwhile, it sheds light on the detailed mechanism how the electrocatalytic conversion of oxygen acts on the real-time response and self-healing protection function of the coating.It is of great importance that the smooth implementation of this research project will provide a theoretical basis for the research and development of effective and “smart” corrosion resistant coatings.

自愈合涂层在金属腐蚀防护应用中具有显著优势，然而，涂层自愈合响应慢限制了其防护效率。本课题基于前期负反馈机制防腐蚀体系研究基础，拟在涂层中引入由牺牲阳极与具有高效氧还原活性的电催化剂构筑的腐蚀电池体系，即氧捕捉阱，构建一种基于负反馈调控电化学催化氧转化机制的自愈合涂层防腐蚀体系。当涂层存在孔隙或缺陷时，携氧电解质的渗入将实时触发氧捕捉阱的氧转化过程，利用高效电催化剂来强化牺牲阳极的吸氧腐蚀，并持续驱动涂层中活化与非活化扩散氧的电催化转化过程，最终在涂层固有孔隙及缺陷处迅速形成耗氧化学屏蔽区，通过其有效的抑制氧的扩散实现涂层对孔隙及缺陷处金属的实时响应自愈合防护功能，最终制备出高效智能的自愈合防腐蚀涂层。本项目意在建立一种基于负反馈激活强化机制的涂层实时响应防腐蚀理论，获得电催化氧转化在实现涂层实时响应自愈合防护功能方面的作用机制，其为新型智能防腐材料的开发与应用提供新思路及理论依据。

本项目意在建立一种基于负反馈激活强化机制的实时响应防腐蚀体系，来改善自愈合涂层防护效率。首先，在涂层中引入氧转化体系，构建一种基于负反馈调控电化学氧转化机制的自愈合防腐蚀涂层。当涂层存在孔隙或缺陷时，携氧电解质的渗入将实时触发电化学氧转化过程，利用高效电催化剂来强化基体的钝化和涂层中扩散氧的电化学转化过程，最终在涂层固有孔隙及缺陷处迅速形成钝化膜或耗氧化学屏蔽区，通过其有效的抑制氧的扩散实现涂层对孔隙及缺陷处金属的实时响应自愈合防护功能。其次，基于电化学氧转化强化钝化防护机制，构建主动化学转化机制增强涂层自愈合防护性能，即利用化学活性缓蚀性填料的溶解、主动刻蚀及沉积转化过程，来强化涂层微缺陷区的腐蚀并转化成膜提高轻金属及其合金表面涂层的自愈合防护效率。再次，基于具有高氧还原活性及电导率的石墨烯基电催化剂加速基体腐蚀的问题，开展了石墨烯基电催化剂表面改性技术研究，引入了石墨烯绝缘聚苯胺改性，硅烷偶联剂修饰、纳米氧化硅绝缘、分子改性及类石墨烯材料等策略，通过阻断腐蚀微电池回路的形成有效抑制了活性填料的腐蚀促进效应。最后，基于自愈合涂层强化腐蚀增强防御机制，设计了具有可控沉降、释放及降解功能的封装缓蚀剂微胶囊，利用微胶囊的缓释与缓蚀功能抑制油井底部腐蚀。该研究拓展了主动防御手段在解决油井腐蚀问题的潜在应用。本项目建立了一种“强化腐蚀增强防御”机制的防腐蚀策略，其为新型智能防腐技术的开发与应用提供新思路及理论依据。