铝粉含量对锌铝涂层微观形貌和耐蚀性的影响

采用扫描电子显微镜(SEM)、动电位极化技术及电化学交流阻抗技术,研究了3种不同铝粉含量的锌铝涂层表面形貌,以及涂层在3.5%NaCl溶液中的浸泡24h的自腐蚀电位、自腐蚀电流密度、阳极钝化情况和阻抗的变化。结果表明:随着铝粉含量的增加,涂层表面逐渐变得光亮、平整;涂层的自腐蚀电位依次升高,自腐蚀电流密度依次降低,当铝粉含量为50%时,涂层动电位极化曲线不存在钝化现象。涂层在3.5%NaCl溶液中浸泡24h的电化学阻抗谱拟合结果显示,铝粉含量较高时,涂层表面形成氧化膜,使得涂层的阻抗增大,降低水的渗入。

Research on Influence of Aluminum Content on the Microstructure and Corrosion Resistance of Zn-Al coatings

The surface morphology of three kinds of Zn-Al coatings with different aluminum powder content were observed under SEM.The self-corrosion potential and current,anode passivation and impedance of the coatings immersed for 24 hours in 3.5% NaCl solution were analyzed by means of the potentiodynamic polarization and electrochemical impendence spectrum.The results show that with increase of content of aluminum,Zn-Al coating gradually becomes brighter and more smooth,the self-corrosion potential and current of the coating turns more positive and reduces in sequence,respectively.The passivation in the polarization curve of the coating doesn’t exist when the content of aluminum comes to 50%.The fitting value of EIS of the coatings immersed for 24 hours in 3.5% NaCl solution shows that the coating with high aluminum content has greater impedance value and lower water infiltration amount because of oxidation film on it.