| LI Jin-yan,HAO Jian-min,CHEN Yong-nan,CHEN Hong.Stripping Process of the Magnesium Alloy Micro-arc Oxidation Coating[J],44(10):27-32,45 |
| Stripping Process of the Magnesium Alloy Micro-arc Oxidation Coating |
| Received:May 22, 2015 Revised:October 20, 2015 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2015.10.005 |
| KeyWord:magnesium alloy micro-arc oxidation stripping of the coating corrosion inhibitor nitrate potassium fluoride |
| Author | Institution |
| LI Jin-yan |
Institute of Material Surface Strengthening, Chang'an University, Xi'an , China |
| HAO Jian-min |
Institute of Material Surface Strengthening, Chang'an University, Xi'an , China |
| CHEN Yong-nan |
Institute of Material Surface Strengthening, Chang'an University, Xi'an , China |
| CHEN Hong |
Institute of Material Surface Strengthening, Chang'an University, Xi'an , China |
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| Abstract: |
| Objective To propose a stripping process of the magnesium alloy micro-arc oxidation coating, so as to improve the reutilization of the magnesium alloy. Methods The chemical solutions which contained nitrate acid, potassium fluoride, citric acid, SDBS and corrosion inhibitor was used to strip of the coating, and the orthogonal experiment was designed to optimize the formulation of the coating stripping solution, using the stripping rate and surface roughness and the judgment criteria. The role of each component in the coating stripping solution was analyzed. The relationship between the weight loss and time during the stripping process, and the relationship of coating thickness with corrosion rate and roughness were discussed. The optimized coating stripping solution was then used to strip the magnesium alloy micro-arc oxidation coating, and the macro- and microstructure of the surface was observed. Results The extreme difference of the chemical reagents on the stripping rate and surface roughness of the magnesium alloy substrate after stripping was in the order of Rnitrate acid >RKF >Rcitric acid >RSDBS >Rcorrosion inhibitor, indicating that the concentration of nitrate acid had the biggest effect on the stripping rate and surface roughness, followed by the concentration of potassium fluoride, and the concentrations of citric acid, SDBS and corrosion inhibitor had the least effect. During the whole process, the weight loss and the time did not have a linear relationship. The weight loss and the stripping rate were high in the beginning and at the end of the process, while in the middle of the process the weight loss and the time had a linear relationship, with a stripping rate lower the initial stripping rate. There were no corrosion products on the surface of the magnesium alloy according to the XRD pattern. As shown by SEM, the pores in the layer after the second micro-arc oxidation treatment on magnesium alloy were compact and uniform, which had no obvious difference with the coating after the first treatment. Conclusion The best composition of the stripping solution for of the magnesium alloy micro-arc oxidation coating was nitric acid 90 mL / L, citric acid 8 g / L, potassium fluoride 35 g / L, dodecyl benzene sulfonic acid sodium 5 g / L, and corrosion inhibitor 6. 5 g / L. This solution led to good stripping of the magnesium alloy arc oxidation coating, causing little damage to the magnesium alloy substrate, and with high stripping rate and low cost. It can therefore be use to repeatedly strip and repair the unqualified magnesium alloy parts covered with the micro-arc oxide coating. |
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