海洋工程防腐涂层力学化学耦合行为及界面失效机理研究

Anticorrosive coatings play a very important role in marine engineering that can protect marine structures from corrosion for long term operation. It has been demonstrated that the mechanical property of the coating/substrate interface is crucial to the performance of anticorrosive coatings. Cathodic blistering and delamination are the most severe and common forms of failure in immersed coating systems caused by the cathodic reaction at the substrate. The transportation of corrosive medium through the coating or along the interface is the controlling step to the cathodic reaction rate, which is affected by chemo-mechanical couplings. Therefore, in order to improve the coating performance, it is essential, in theoretical and experimental respects, to illustrate its chemo-mechanical behavior and identify the mechanism of coating/substrate system failure. This project is aimed to provide the theoretical basis and evolution method to optimize the material and structure of anticorrosive coatings. Using optical shearing interferometry and scan Kelvin probe, the chemo-mechanical behavior during the corrosive medium transportation and the mechanism of failure for coating/substrate interface will be studied in theory and experiment. This research will investigate, the chemo-mechanical coupling effects during transportation of corrosive medium, the mechanism of cathodic delamination and blistering as well as on-line testing method and technique for coating/substrate interface failure.

防腐涂层在海洋工程中具有重大应用，是确保海洋工程装备长期可靠运行的主要防腐措施。实践证明，涂层/基体界面力学性能对涂层发挥防腐作用具有决定性影响。对处于全浸没工作环境的涂层，阴极剥离和起泡是最常见也是最为严重的界面失效形式。基体上发生的阴极反应是界面失效的主要原因，在力学化学耦合作用下，腐蚀介质在涂层中及沿界面的传输过程是阴极反应速率的控制步骤。因此，为提高涂层防腐性能和可靠性，迫切需要建立完备的实验方法和理论体系来阐明涂层力学化学耦合行为及界面失效机理。本项目以有机防腐涂层为研究对象，通过激光剪切干涉方法和扫描Kelvin探针技术，建立涂层力学化学耦合行为及界面失效机理的理论描述和实验表征方法，为优化涂层材料结构设计提供理论依据和评价手段。主要内容包括：阐明腐蚀介质传输过程中的力学化学耦合作用机制；建立防腐涂层界面失效机理；开发涂层/基体界面失效行为的在线检测方法和技术。

防腐涂层广泛地应用于海洋工程、油气输运、交通运输、航空航天等行业，是确保设备长时间安全运行的关键防腐屏障。揭示涂层失效模式及其机理，对优化涂层设计、增强涂层使用寿命具有重要意义。本项目以防腐涂层及金属基体为研究对象，研究在腐蚀介质输运过程中的力化学耦合作用机制、涂层失效机理及涂层应力在线检测方法。项目取得的重要结果如下：.1. 建立了考虑力化学耦合效应的腐蚀介质扩散方程，揭示了腐蚀介质输运过程中的力化学耦合作用机制。将涂层和基体均当作薄板进行处理，根据涂层/基体系统平衡方程，建立了腐蚀介质浓度分布与涂层应力之间的关系；在腐蚀介质化学势中考虑涂层应力影响，建立了腐蚀介质在涂层中的扩散方程，进而阐明扩散过程中的力化学耦合作用机制。结果表明，涂层应力为压应力，且随时间变化将趋于稳定值。.2. 基于界面断裂力学理论建立了涂层/基体界面失效判据，阐释了涂层阴极起泡机理。提出了涂层/基体界面失效准则，给出了防腐涂层/金属基体界面能量释放率预测方法，在此基础上，分析了涂层杨氏模量、泊松比、涂层厚度及初始缺陷尺寸对能量释放率的影响。结果表明，涂层杨氏模量越大，界面裂纹能量释放率越高；存在临界涂层厚度与初始缺陷尺寸，使界面裂纹能量释放率达到极大值。.3. 基于相干梯度敏感技术提出了涂层应力在线检测方法，从理论和实验两方面对系统曲率测量的灵敏度和测量精度进行了分析，结果表明，曲率测量灵敏度与两光栅间距和光栅节距的比值成正比，测量精度取决于所用光源波长和照明区域大小，根据研究结果，确定了兼顾灵敏度与精度的光学元件测量参数。.本项目研究结果揭示了腐蚀介质输运过程中的力化学耦合作用机制，为防腐涂层失效判定提供了定量依据，同时为优化涂层设计提供了力学准则和实验测量手段。