铝合金表面聚吡咯镀层的制备及其防腐蚀性能

采用恒电位法在铝合金片(Al)上电镀吡咯单体电化学聚合形成聚吡咯(polypyrrde,PPy)镀层,研究其防腐性能。采用扫描电子显微镜(SEM)、红外光谱(FTIR)、拉曼光谱(Raman)以及X射线衍射(XRD)表征样品微观形貌与结构组成,接触角测量仪与热重分析仪分别表征样品的疏水性能与热稳定性,采用腐蚀形貌图、极化曲线以及EIS表征样品的防腐性能。结果表明:聚吡咯镀层均匀、致密展现出良好的机械屏蔽性能。聚吡咯为无定形结构,吡咯单体之间以C—C键连接成链式聚吡咯。聚吡咯镀层表现为疏水性能,且热稳定性良好。浸泡在3. 5%Na Cl溶液中136 h后,铝合金出现大量点蚀现象,而聚吡咯镀层并没有出现严重腐蚀现象。聚吡咯镀层的腐蚀电流密度比铝合金更小,对铝合金保护率达到80. 8%。此外,聚吡咯镀层的溶液电阻与电荷转移电阻比铝合金高很多,表明其对溶液中电解质离子有更强的阻碍作用以及低电荷转移速率,防腐性能优异。

The corrosion Resistance of Polypyrrole coating on Aluminum Alloy

Polypyrrole (PPy) coating is formed by electroplating pyrrole monomer on aluminium alloy sheet (Al) using potentiostatic method.The microstructure and structure of the samples are observed and analyzed by SEM,FTIR,Raman and XRD.Hydrophobicity and thermal stability of sample are measured by contact angle measuring instrument and thermogravimetric analyzer.Corrosion microstructure, polarization curve and EIS analyse the antiseptic properties of samples.The results show that the polypyrrole coating is uniform and compact, showing good mechanical shielding performance.Polypyrrole is amorphous, and the pyrrole monomers are linked by C-C bond to form chain polypyrrole.The polypyrrole coating shows hydrophobicity and good thermal stability.After soaking in 3.5% Nacl solution for 136h, a large number of pitting corrosion phenomena occurr in aluminum alloy, but there is no serious corrosion phenomenon in polypyrrole coating.The corrosion current density of polypyrrole coating is lower than that of aluminum alloy, and the protective rate of polypyrrole coating is 80.8%.In addition, the solution resistance (Rs) and charge transfer resistance (Rct) of polypyrrole coating are much larger than that of aluminum alloy, indicating that the polypyrrole coating has a stronger hindrance to electrolyte ions in the solution and lower charge transfer rate.Polypyrrole coating has excellent anticorrosion property.