电化学阳极钝化技术应用于钛金属在海水中的防腐防污研究

Titanium and titanium alloys present good corrosion resistance in the marine environment. However, they are susceptible to serious biofouling, which could cause the change of local environmental on the surface of the titanium materials, such as the decrease in the content of dissolved oxygen. The passive film cannot be effectively repaired once it is damaged and the failure of the titanium material will occur. Based on the wide passivation range and high pitting potential of titanium in seawater, this project proposes the idea of using electrochemically anodic passivation for anticorrosion and antifouling. The corrosion resistance of titanium materials can be improved through passivation by applying anodic potential directly in seawater and the passive films can be repaired if they were damaged. Meanwhile, the adhesion behavior of microorganisms can be influenced by the modification of the surface film caused by the anodic passivation. Consequently, the biofouling can be reduced. The project will focus on the study of the dissolving - passivation behaviors and the mechanism of the passive film on the titanium surface in seawater obtained from electrochemically anodic passivation. Furthermore, the influence of different passive films on the adhesion behavior of microorganisms will also be investigated. The effects of different potentials on the corrosion resistance and microbial adhesion will be determined. Additionally, the potential ranges used to enhance the corrosion resistance and to reduce the adhesion rate of marine organisms will be obtained. The knowledge obtained from this research is able to provide a simple and feasible solution for severe biofouling of titanium and titanium alloys in seawater, which is of both theoretical and practical significance.

钛和钛合金在海水中有很好的耐蚀性，但容易遭受海生物污损，污损会造成钛材表面局部环境变化，如溶解氧降低，使得表面钝化膜破损后无法有效修复，长期积累后使得钛材失效。针对钛在海水中钝化区间宽，点蚀电位高的特性，本项目提出使用电化学阳极钝化的思路来进行防腐和防污，通过在海水中直接对钛材进行阳极电位钝化来提高其耐蚀性，并可在钝化膜受到损伤时得到及时修复，同时利用阳极钝化时改变钝化膜表面性质来影响海洋微生物的附着从而降低污损。重点研究电化学阳极钝化对金属表面钝化膜在天然海水和除氧海水中的形成和溶解-修复的影响和机理，以及不同钝化膜表面性质对微生物附着行为的影响规律，明确不同电位对膜层耐蚀性和微生物附着的影响规律，获取可用于加强膜层耐蚀性和降低微生物附着率的电位区间，从而对电位进行有效调控。本项目可为钛材在海洋中的防腐防污提供一项简单易行的方法，具有明确的理论和实际意义。

钛和钛合金在海水中有很好的耐蚀性，但容易遭受海生物污损，污损会造成钛材表面局部环境变化，如溶解氧降低，使得表面钝化膜破损后无法有效修复，长期积累后使得钛材失效。针对钛在海水中钝化区间宽，点蚀电位高的特性，本项目提出使用电化学阳极钝化的思路来进行防腐和防污，通过在海水中直接对钛材进行阳极电位钝化来提高其耐蚀性，并可在钝化膜受到损伤时得到及时修复，同时利用阳极钝化时改变钝化膜表面性质来影响海洋微生物的附着从而降低污损。重点研究了电化学阳极钝化对金属表面钝化膜在海水中的形成和溶解-修复的影响和机理，以及不同钝化膜表面性质对微生物附着行为的影响规律，明确了不同电位对膜层耐蚀性和微生物附着的影响规律，并获取了可用于加强膜层耐蚀性和降低微生物附着率的电位区间，从而对电位进行有效调控。取得的重要结果如下：1）阳极电位越高，钛表面钝化膜层越厚，钝化膜越厚膜层耐蚀性越好，当电位处于1.4~1.8V（Vs SCE）时膜层会发生溶解行为，成分中会出现三价Ti，此时会影响膜层的均匀性和耐蚀性。 2）在施加的电位低于1.0V和高于1.8V时，钛表面以氧化成膜过程为主，因此当表面氧化膜受到破坏时，可迅速得到恢复；而当电位处于1.0V~1.8V之间时，钛表面氧化膜本身就处于一种不太稳定的状态，处于一种溶解-自修复的过程，当受到外部破坏时，会短暂破坏这个平衡，可能无法得到完全的修复。3）无论是在微藻粘附实验中，还是在藤壶幼体附着实验中，Ti1.4和Ti1.5均表现出较低的附着密度和附着率。当钛金属表面存在电流输出时，电流较高的电位区间明显降低微藻的附着密度。4）提出了一种针对钛金属材料的有效防腐防污的保护技术，但长期试验有待验证，一旦效果得到验证，可直接在全钛船体上或钛制管道上进行设计使用。