Li C Q, Zhu M Y, Ou J F, Lu Y L, Wang F J, Li W
School of Materials and Engineering, Jiangsu University of Technology Changzhou 213001 P. R. China
RSC Adv. 2018 Aug 20;8(51):29201-29209. doi: 10.1039/c8ra05200j. eCollection 2018 Aug 14.
For superhydrophobic surfaces immersed in water, a thin layer of air could be entrapped in the solid/liquid interface. This air may hinder the diffusion of dissolved corrosive species (such as Cl ions in water) to the metallic substrate and, consequently, protect the metal from corrosion. However, in the dynamic water, the relative motion between the solid and the liquid would labilize the entrapped air and, consequently, decrease the corrosion resistance. In this work, to clarify the role of water flow velocity in such corrosion behavior, a superhydrophobic surface on aluminum substrates coded as Al-HCl-HO-BT-SA was prepared by sequential treatment with HCl, boiling water, bis-(γ-triethoxysilylpropyl)-tetrasulfide (KH-Si69, BT) and stearic acid (SA). The contrast samples coded as Al-HCl-BT-SA, Al-HCl-HO-SA, and Al-HCl-SA were also prepared similarly by omitting the treatment in boiling-water, the BT passivation, and the treatment in boiling-water/passivation by BT, respectively. These samples were then immersed into an aqueous solution of NaCl with different flow velocity (0, 0.5, 1.0, 1.5, and 2.0 m s), and its dynamic corrosion behavior was investigated. The results showed that, as the flow velocity increased, the corrosion resistance of the Al-HCl-HO-BT-SA sample indeed deteriorated. However, compared with the contrast samples of Al-HCl-BT-SA, Al-HCl-HO-SA, and Al-HCl-SA, the deterioration in corrosion resistance for the Al-HCl-HO-BT-SA sample was much lower, implying that the dynamic corrosion resistance of the superhydrophobic surfaces was closely related with the micro-structures and the organic passivated layers. The present study therefore provided a fundamental understanding for the applications of superhydrophobic samples to prevent the corrosion, especially, for various vessels in dynamic water.
对于浸没在水中的超疏水表面，在固/液界面处可能会截留一层薄薄的空气。这种空气可能会阻碍溶解的腐蚀性物质（如水中的氯离子）扩散到金属基底，从而保护金属免受腐蚀。然而，在动态水流中，固体与液体之间的相对运动会使截留的空气不稳定，进而降低耐腐蚀性。在这项工作中，为了阐明水流速度在这种腐蚀行为中的作用，通过依次用盐酸、沸水、双（γ-三乙氧基硅丙基）四硫化物（KH-Si69，BT）和硬脂酸（SA）处理，在铝基底上制备了编码为Al-HCl-HO-BT-SA的超疏水表面。同样地，通过分别省略沸水处理、BT钝化处理以及沸水/BT钝化处理，制备了编码为Al-HCl-BT-SA、Al-HCl-HO-SA和Al-HCl-SA的对比样品。然后将这些样品浸入不同流速（0、0.5、1.0、1.5和2.0 m/s）的氯化钠水溶液中，研究其动态腐蚀行为。结果表明，随着流速增加，Al-HCl-HO-BT-SA样品的耐腐蚀性确实变差。然而，与Al-HCl-BT-SA、Al-HCl-HO-SA和Al-HCl-SA对比样品相比，Al-HCl-HO-BT-SA样品耐腐蚀性的变差程度要低得多，这意味着超疏水表面的动态耐腐蚀性与微观结构和有机钝化层密切相关。因此，本研究为超疏水样品在防止腐蚀方面的应用，特别是在动态水中的各种容器中的应用，提供了基本的认识。
