摘要
为解决铝合金表面耐蚀性差的问题,采用两种方法在铝合金表面制备一种复合膜层。首先利用微弧氧化(MAO)技术在铝合金表面原位生长陶瓷层。然后利用化学方法在陶瓷层表面原位生长出类水滑石薄膜(LDH)。最后利用硬脂酸对复合膜层进行表面修饰,以达到超疏水表面。利用扫描电镜(SEM)、 X射线衍射(XRD)、接触角测量仪及电化学工作站分别分析了微弧氧化陶瓷层及复合膜层的表面形貌、物相结构、疏水性以及耐腐蚀性能。结果表明:类水滑石片层物将微弧氧化陶瓷层的缺陷(微孔及微裂纹)完全封闭,并且制备的复合膜层构建出了微/纳二元结构。经表面修饰剂修饰后复合膜层的接触角为155.2°,而微弧氧化陶瓷层的接触角为17.5°。利用电化学工作站测试的极化曲线结果显示,超疏水复合膜层的腐蚀电流密度比微弧氧化陶瓷层降低了约两个数量级;而阻抗图谱分析表明,超疏水复合膜层具有更优异的耐蚀性。
In order to solve the poor corrosion resistance of aluminum alloy surface, two methods were used to prepare a composite film on the surface of aluminum alloy. Firstly, the ceramic layer was grown in situ on the surface of aluminum alloy by micro-arc oxidation(MAO). Then the hydrotalcite-like film(LDH) film was grown in situ on the surface of ceramic layer by chemical method. Finally, the composite film surface was modified with stearic acid to achieve superhydrophobic surface. The surface morphology, phase structure, hydrophobicity and corrosion resistance of MAO ceramic layer and composite film were analyzed by scanning electron microscope(SEM), X-ray diffraction(XRD), contact angle measuring instrument and electrochemical workstation, respectively. The results showed that the micro-pores and micro-cracks of MAO ceramic layer were completely closed by LDH nano-sheet. Simultaneously, the micro/nano structure was built by the composite film. In addition, the contact angle of composite film after modification was 155.2°, while the MAO ceramic layer was 17.5 °. The results of the dynamic potential polarization curve showed that the corrosion current density of superhydrophobic composite film was reduced by 1~2 orders of magnitude than that of MAO ceramic layer. Similarly, the impedance spectra showed that the superhydrophobic composite film had more excellent corrosion resistance.
引文
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