通过化学浸渍在Al管表面钝化生成一层致密疏水的有机杂化膜. 硫酸铜点滴实验、析氢实验和铜盐加速乙酸盐雾试验都表明, 杂化膜显著提高了Al管的耐腐蚀性能,耐蚀效果超过了铬酸盐钝化膜. 电化学Tafel极化曲线和交流阻抗谱(EIS)测定表明, 杂化膜使Al的自腐蚀电位正移, 阻抗值增大, 自腐蚀电流密度降低, 有效降低了Al的腐蚀速率. 附着力及弯折性能实验结果表明, 杂化膜具有良好的附着力和耐弯折性能. SEM和AFM对杂化膜表面形貌分析显示, 杂化膜表面均匀、致密和平整, 膜层由大量无定形的固体颗粒沉积而成, 覆盖度高. EDS检测发现, 杂化膜主要包含Al, C, O, Si和P等元素. 成膜和耐蚀机理分析表明, 有机掺杂钝化液中各组分间发生了反应, 在Al管表面起到协同钝化作用, 均匀成膜, 从而有效增强了Al管的耐腐蚀性能.
Dense and hydrophobic organic hybrid films were deposited on the surface of aluminum tubes by the method of chemical immersion. Corrosion resistance of hybrid films was examined by bluestone drips, hydrogen evolution and copper accelerated salt spray tests, and the results show that the hybrid film significantly increases the corrosion resistance of aluminum tubes, with better protection than that of chromate passivation films. Tafel polarization curves and electrochemical impedance spectroscopy (EIS) were employed to investigate the electrochemical properties of hybrid films, the results indicate that the hybrid film greatly enhances the resistance of Al and reduces obviously the corrosion current density, which results in effective decrease to the corrosion rate of Al. Adhesion and bending experiments show that hybrid films have good adhesion and play a good performance on bending resistance. The surface structure and composition of hybrid films are analyzed using SEM, AFM and EDS. It is found that the surface of hybrid films, mainly consisting of Al, C, O, Si and P elements, is smooth, uniform and dense. The film surface is deposited a large number of amorphous solid granules with high coverage. Mechanism analysis of hybrid films’ formation and anticorrosion indicates that the reactions are taken place in the components of the organic hybrid passivation solution, synergistic passivation is carried out on the surface of aluminum tubes, and then uniform films are obtained, which effectively enhance the corrosion resistance of aluminum tubes.
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