| SHAO Zhong-cai,DAI Shi-hang,ZHANG Yu,ZHAO Jia-xin,DAI Yong-qi,WEI Shou-qiang.Effects of Copper, Cobalt and Nickel Ions on Micro-arc Oxidation Film of Magnesium Alloy[J],47(4):127-132 |
| Effects of Copper, Cobalt and Nickel Ions on Micro-arc Oxidation Film of Magnesium Alloy |
| Received:September 15, 2017 Revised:April 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.04.019 |
| KeyWord:magnesium alloy micro arc oxidation corrosion resistance copper ions cobalt ions nickel ions |
| Author | Institution |
| SHAO Zhong-cai |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
| DAI Shi-hang |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
| ZHANG Yu |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
| ZHAO Jia-xin |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
| DAI Yong-qi |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
| WEI Shou-qiang |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
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| Abstract: |
| The work aims to improve the corrosion resistance of magnesium alloy micro arc oxidation film. Copper, cobalt and nickel ions were respectively added to the electrolyte system composed of Na2SiO3-NaOH-Na2B4O7 for micro arc oxidation of AZ91D magnesium alloy. The effect of ion species and composition on the film properties was studied. The corrosion resistance of film was measured by drop test; the electrochemical performance of film was measured by electrochemical workstation; the surface morphology and elements of generated micro-arc oxidation film were analyzed by scanning electron microscopy (SEM) and energy spectrum diagram (EDS). When cobalt ion, copper ion and nickel ion were added into the electrolytic solution, the corrosion resistance of the micro arc oxidation film on the magnesium alloy was improved and the copper ion played the most important role. With addition of 1.5 g/L copper ions, the drop time of micro arc oxidation film on magnesium alloy was improved by 77.3 s, and the corrosion resistance of the film increased significantly. From polarization curve analysis, the corrosion current of oxide film without metal ions was 1.092×10-5 A/cm2 and the corrosion potential was 1.487 V. When concentration of cobalt, copper and nickel ions was respectively 2 mol/L, 1.5 mol/L and 3 mol/L, the corrosion current was respectively 3.912´10-6 A/cm2, 6.027´10-6 A/cm2 and 2.167´10-6 A/cm2 and thecorrosion potential was respectively 1.412 V, 0.832 V and 1.047 V. The corrosion current of the micro arc oxidation film prepared by adding metal ions reduced by 1 orders of magnitude, and the positive shift of the potential was in different degrees. Added with copper ions, the corrosion potential increased by 0.655 V. With the addition of metal ions, the number of voids and holes on the surface of the micro arc oxidation film reduced and decreased in a certain degree, which increasedthe density and uniformity of the film. The addition of a certain amount of copper, cobalt and nickel ions in the electrolyte can improve the corrosion resistance of AZ91D magnesium alloy micro arc oxide film, in which the effect of copper ion was the most obvious. |
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