环氧富锌涂层对AZ91D镁合金的腐蚀防护能力研究

目的研究环氧富锌涂层对AZ91D镁合金的腐蚀防护能力。方法采用机械喷涂法在AZ91D镁合金表面制备一种保护性的环氧富锌涂层。采用电化学阻抗谱(EIS)研究环氧富锌涂层在0.5 mol/L的Na2SO4腐蚀溶液中的电化学腐蚀行为及其对镁合金的腐蚀防护能力。结果浸泡初期,环氧富锌涂层的阻抗谱中只出现一个时间常数,暗示着环氧富锌涂层优异的阻挡层作用;浸泡48 h后,环氧富锌涂层阻抗谱中出现两个时间常数,高频和低频时间常数分别对应环氧富锌涂层中高聚合的介电性质和锌粉的活性溶解;浸泡336 h后,环氧富锌涂层仍具有很高的阻抗模值,表明此时环氧富锌涂层对镁合金仍能提供良好的腐蚀防护。结论环氧富锌涂层在0.5 mol/L Na2SO4腐蚀溶液中能对AZ91D镁合金提供很好的腐蚀防护。

Research on the Corrosion Protection Properties of Zn-rich Epoxy Coating Provided for AZ91D Magnesium Alloy

Objective To investigate the corrosion protection properties of Zn-rich epoxy coating provided for AZ91D magnesium Alloy. Methods A protective Zn-rich epoxy coating was prepared on AZ91D magnesium alloy by a method of mechanical spray. The electrochemical corrosion behavior and corrosion protection properties of Zn-rich epoxy coating provided for magnesium were investigated with electrochemical impedance spectroscopy （EIS） in 0.5 mol/L Na2SO4 corrosive media. Results In the initial immersion stage,the coating presented only one time constant suggesting the excellent barrier-type coating. At an immersion time of 48 h,two time constants were observed in the electrochemical impedance spectroscopy which corresponded to the dielectric properties of polymer in the high-frequency range and the active dissolution of Zn particles in the low-frequency range. At an immersion time of 336 h,the Zn-rich epoxy coating exhibited highly resistant module which suggested that Zn-rich epoxy coating still provided excellent corrosion protection for AZ91D magnesium alloy. Conclusion The Zn-rich epoxy coating could provide excellent corrosion protection for the AZ91D magnesium alloy in 0.5 mol/L Na2SO4 corrosive media.