残存水影响下涂层自修复与低碳钢腐蚀过程的竞争机制研究

The protective coating based on isocyanate microcapsules has a short protective term after self-healed by mechanical scratched triggering, and this phenomenon has been the critical issue of limiting the application of self-healing coatings. While, residual water could exist between the healed layer and metal body in the self-healing process. Residual water could be the vulnerable point of the second time corrosion in the healed area, but the failure mechanism has not yet been clearly learned. The traditional electrochemical techniques could offer average electrochemical data, and could not obtain signals caused by the local area, such as the signals in the healed layer forming process. Considering this limiting point, this work proposes using the testing methods which include Scanning Kelvin Probe, Scanning Vibrating Electrode Technique, Alternating-Current Scanning Electrochemical Microscopy, Fourier transform infrared spectroscopy tests, and fluorescent probes etc., to learn the contribution of residual water content to the forming of healed layer and metal corrosion, to investigate the influence mechanism of corrosion product that participates in the self-healing process. Then, this work establishes the coupling dynamic model on self-healing coating process and corrosion process. The influence mechanism of residual water participating in the self-healing process and corrosion will be clarified. Therefore, it has a significant application value of theoretically clarifying the accelerated failure mechanism of corrosion and self-healing coating coupled with residual water, and practically designing protective coating and developing long-term scratched trigger coating.

基于异氰酸酯类微胶囊的自修复防腐涂层经机械划伤、自修复后的服役寿命较短，这一问题严重制约这类涂层的推广应用。在涂层自修复过程中会有残存水存留在修复层与金属界面之间，残存水可能会演变为诱发修复区域腐蚀的薄弱点，但机理尚不清楚。考虑到传统电化学手段仅能提供平均电化学信息，无法获取修复层形成等重要环节所引起的局部电化学信息变化这一局限，本项目拟利用扫描开尔文探针、扫描振动电极、交流扫描电化学显微镜与传统的红外光谱、荧光探针技术相结合，定量研究残存水含量对修复层形成和修复层下低碳钢腐蚀的贡献，探究腐蚀产物参与自修复过程的影响机制，分析建立涂层自修复的反应动力学和低碳钢腐蚀动力学的耦合模型，阐明残存水参与影响涂层自修复过程和低碳钢腐蚀过程的竞争机制。本研究对于在理论上弄清残存水对低碳钢腐蚀和自修复涂层的加速失效机制，在实践上指导自修复涂层设计、发展长效自修复涂层具有重要意义。

有机涂层是防止金属腐蚀的重要手段之一，微孔缺陷不可避免的形成于涂层制备过程中，成为渗水通道；而且涂层下金属腐蚀过程与水密不可分。本项目以抑制有机涂层渗水失效和金属腐蚀过程中的“水”为切入点，采用细乳液聚合法制备异氰酸酯类自修复微胶囊，实现尺寸调控，以此为基础制备自修复涂层和磁性梯度涂层。利用核磁共振、红外光谱、微区电化学等测试，确认了异氰酸酯遇水固化后形成聚氨酯的分子结构，从分子角度证明了自修复微胶囊遇水固化的特性。明确了腐蚀产物中对自修复过程具有Lewis酸催化作用的成分，阐明了残存水对涂层自修复过程和修复层下低碳钢腐蚀的作用规律，探明了腐蚀产物对自修复过程的影响规律，揭示了残存水导致加速涂层自修复和局部腐蚀加速的竞争机制。研究了碳纳米管对残存水在涂层中渗水速率的影响。利用分子模拟方法研究了铁基体表面的等离子体处理作用，比较醇酸树脂在未处理铁基体和等离子体处理铁基体表面吸附能的变化规律，证明了等离子体表面处理可有效提高自修复涂层与金属表面的吸附能力，抑制残存水侵蚀。基于壳聚糖微球负载植物天然萃取物合成制备了海工自修复涂层，探讨了涂层的自钝化、自修复能力。探索性的开展了基于形状记忆成膜物的智能自修复涂层研究。基于形状记忆聚氨酯和阿洛丁微胶囊的优势性能和不同因素触发特点，研究了复合体系在金属表面的协同自修复机制。研究了自修复防腐涂层在模拟深海交变压力下的失效行为，对比研究了不同压力环境下的电化学参数和阴极剥离面积影响规律，阐述了压力环境和阴极极化电位对涂层阴极剥离的作用机制。本项目可为改善有机涂层在海洋环境中的防腐性能提供科学依据，具有重要的应用价值。项目在研期间共发表论文19篇，其中项目负责人发表论文13篇，课题组其他成员发表论文6篇；申请国家发明专利6项；专利获得授权1项。