超疏水纳米杂化聚硅氧烷智能涂层的制备及失效机理

Coating is commonly used to provide the corrosion protection for steels in marine environment. However, the coating can be susceptible to form the bubble, pinhole and filiform corrosion during the paint process and the long-term use, causing the localized corrosion of metal and the failure of coating. Effective surface techniques have been developed aiming to reduce the failure of coating, among which smart coating (self-healing coating) is effective techniques. In this project, the superhydrophobic polysiloxane film was prepared on the surface of representative marine engineering steel (Q235 steel) by anodic oxidation, self-assembly and nano hybrid technology. The smart coating was further prepared based on the obtained superhydrophobic polysiloxane film. In order to investigate the relationship between the microstructure and the adhesion, corrosion resistance of coating, the smart coatings were characterized by SEM, AFM and XPS, while the corrosion barrier and inhibition mechanism of these films were mainly studied with the usual electrochemical techniques. Moreover, the failure process of smart coating / carbon steel system was identified by multi-factor coupling accelerated test and micro-zone electrochemical scanning. This work is conducive to research how to increase the coating adhesion, explore how to release the corrosion inhibitor, and clarify the failure mechanism of the smart coating in multi environmental factors. Furthermore, this research will establish the foundation to reveal the relationship between microstructure and corrosion resistance of the coating, and provide the new ideas for the development of smart coatings.

涂层是海洋环境中钢结构的有效防护手段之一，但在涂装及长期使用过程中容易发生鼓泡、针孔、丝状腐蚀等现象，引发金属的局部腐蚀，导致涂层失效。涂层自身的修复能力是解决该问题的关键所在。本项目拟通过阳极氧化、自组装及纳米杂化等技术在代表性海洋工程用钢（Q235碳钢）表面制备超疏水聚硅氧烷薄膜，在此基础上选择性制备智能涂层。通过SEM、AFM、XPS等手段分析涂层微观结构及元素组成，采用电化学方法评价涂层在海洋环境中的防腐蚀性能，探讨微观结构对智能涂层附着力及防腐蚀性能影响规律。运用多因素耦合等效加速试验技术和微区电化学扫描表征智能涂层/碳钢体系的腐蚀失效过程。这些工作的开展对于研究提高涂层附着力的作用机制，探索缓蚀剂在仿生结构中的封装与释放原理，澄清多环境因素耦合下智能涂层失效机理等方面有重要意义，为进一步研究微观结构与涂层防腐性能的内在关系奠定基础，并为新型智能涂层的开发提供思路。

涂层是海洋环境中钢结构的有效防护手段之一。涂层自身的修复能力是解决涂层失效问题的关键所在。本项目完成在碳钢表面制备超疏水聚硅氧烷薄膜，在此基础上选择性制备智能涂层。主要研究成果如下：(1)当乙二胺浓度为3.00 mol/L，水热温度为140 ℃，水热反应时间为6 h时，制备的薄膜与水滴的接触角为152°，即为超疏水薄膜。该薄膜的缓蚀效率可达98.8 %，且具有较低的粘附性能和较好的自清洁性能。(2)智能涂层释放的聚天冬氨酸形成具有较高阻隔性的薄膜，有效地提高了涂层的耐蚀性，并以1 wt.%纤维素+4 wt.% 聚天冬氨酸的涂层样品自修复性能最好。(3)所制备的超疏水-自修复复合型涂层由厚度为20 μm的环氧树脂涂层，30 μm的木质纤维素与聚天冬氨酸的修复层，和15μm的超疏水环氧树脂层组成。该复合型涂层的接触角为158°，达到超疏水，且随着环氧树脂含量的降低，涂层的硬度逐渐下降。(4)碳钢表面自组装硅烷膜中Fe-O-Si和Si-O-Si等基团与金属表面结合紧密，覆盖了基体，在碳钢持续盐雾腐蚀初期起到一定防护作用，随着时间的延长，防护作用逐渐下降。以上结果对金属表面制备超疏水薄膜以及新型智能涂层的开发提供了重要的参考价值与理论依据。

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