AZ91D镁合金在氯化胆碱-尿素离子液体中电镀Zn的研究

ELECTRODEPOSITION OF Zn ON AZ91D IN CHOLINE CHLORIDE-2UREA IONIC LIQUID

采用价廉、环保和稳定性好的氯化胆碱-尿素离子液体作为溶剂,在AZ91D镁合金上进行电镀Zn研究,包括AZ91D基体的前处理机制及电流方式对镀层形貌及耐腐蚀性能的影响。结果表明,经前处理的AZ91D镁合金在氯化胆碱-尿素离子液体中电镀可获得Zn镀层,脉冲电镀比恒流电镀更利于获得致密均匀、与基体结合良好的Zn层;脉冲电镀Zn层后,基体AZ91D镁合金的开路电位OCP从-1610 mV正移至-1072 mV,腐蚀电流I_(corr)从14.9μA/cm^2降为6.9μA/cm^2,与纯Zn(OCP=-1078 mV,I_(corr)=6.6μA/cm^2)相当。

In aqueous electrolytes,electrodeposition on Mg alloys is still a challenge because Mg has high chemical reactivity.The process becomes more complicated in aqueous electrolytes owing to the hydrogen evolution.Ionic liquids as non-aqueous electrolytes in electrodeposition have received much attention from researchers.In present study,choline chloride-urea ionic liquid,which is sustainable,biodegradable and stable in air and water,was used as the solvent and the electrodeposition of Zn on AZ91D magnesium alloy was investigated.The pretreatment mechanism of the AZ91D substrate and the effect of current mode on the Zn coatings were studied by scanning electron microscope（SEM/EDX）.The corrosion resistance of the deposited Zn coatings were studied by electrochemical testing.The results show,Zn coatings could be electrodeposited on pretreated AZ91D substrate from choline chloride-urea ionic liquid.Application of pulse deposition was superior to galvanostatic deposition in producing dense,uniform and cohesive Zn coating.By pulse deposition Zn coatings,the OCP of AZ91D substrate moves in positive direction from-1610 mV to-1072 mV and the corrosion current density I_（corr） decreases from 14.9μA/cm^2 to 6.9μA/cm^2,comparable to those of pure Zn （OCP=-1078 mV,I_（corr）=6.6μA/cm^2）.