本研究利用AlCl3-EMIC离子液体在AZ91D镁合金表面电镀铝金属,探讨离子液体组成及电流密度对电镀层性质的影响.研究结果显示铝金属可以成功地电镀于AZ91D镁合金表面上.在-0.2 V的电位下,在60 m/o AlCl3离子液体中可以获得较佳的电镀铝层.另外,在低定电流密度下进行电镀,电流效率较佳,镀层较厚.于3.5%NaCl(by mass)溶液中,铝金属镀层可以大幅提升镁合金之开路电位,并使其表面活性下降.电化学交流阻抗频谱分析显示,镁合金裸材于3.5%NaCl(by mass)水溶液中之极化阻抗值约为470~510Ω.cm2,镀铝之镁合金极化阻抗值则可提升至5200Ω.cm2.极化曲线则显示,镀铝之镁合金可以被钝化,其钝化电流密度低至5×10-5A/cm2.
关键词：
镁合金; 离子液体; 电镀; 铝; 耐蚀性
Electrodeposition of a metallic aluminum on a magnesium alloy in acidic aluminum chloride-1-ethyl-3-methylimidazolium chloride ionic liquids(AlCl3-EMIC) was investigated.The effects of current density and AlCl3 content in the ionic liquid on the electrodeposition behavior were studied.The results showed that aluminum could be successfully electrodeposited on the AZ91D substrate.At-0.2 V,the ionic liquid containing 60 m/o AlCl3 was optimum for Al electrodeposition.The current efficiency was higher if electrodeposition was performed at a lower applied current density.The existence of Al coating could caused a substantial increase in open circuit potential,reducing the susceptibility of Mg alloy to corrosion.The results of electrochemical impedance spectroscopy showed that Al coating could cause the increase in the polarization resistance of a bare Mg alloy from 470~510 Ω·cm2 to 5200 Ω·cm2 in 3.5%(by mass) NaCl solution.Furthermore,the results of potentiodynamic polarization measurements showed that Al-coated Mg alloy could be passivated with the passive current density as low as 5×10-5 A/cm2.
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