| CUI Yong-hui,SHAO Zhong-cai,LI Xue-tian,WEI Shou-qiang.Effect of Additives on Rare Earth Conversion Coatings on Aluminum Alloys[J],48(5):225-231 |
| Effect of Additives on Rare Earth Conversion Coatings on Aluminum Alloys |
| Received:November 22, 2018 Revised:May 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.05.033 |
| KeyWord:aluminum alloys rare earth chrome-free passivation corrosion resistance conversion coating electrochemist |
| Author | Institution |
| CUI Yong-hui |
Shenyang Ligong University, School of Environmental and Chemical Engineering, Shenyang, , China |
| SHAO Zhong-cai |
Shenyang Ligong University, School of Environmental and Chemical Engineering, Shenyang, , China |
| LI Xue-tian |
Shenyang Ligong University, School of Environmental and Chemical Engineering, Shenyang, , China |
| WEI Shou-qiang |
Shenyang Ligong University, School of Environmental and Chemical Engineering, Shenyang, , China |
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| Abstract: |
| The work aims to improve the corrosion resistance of rare earth conversion coatings on aluminum alloys. Study the effects of different additives (H3BO3, Na3C6H5O7, Na3PO4, Na2SiO3, NH4HF2, NaF, (NH4)2C2O4) on the rare earth conversion coating, and compound the additives with positive effects and optimize the formula by response surface methodology. Characterization of rare earth conversion coatings prepared under different conditions was evaluated by scanning electron mi-croscopy (SEM), energy dispersive spectroscopy (EDS), and electrochemical testing. The results showed that the addition of NaF, Na3C6H5O7 and Na3PO4 to the base conversion solution can improve the electrochemical performance of the rare earth conversion coating. After compounding and optimizing the formula, the optimal additive system was 0.68 g/L NaF+0.80 g/L Na3C6H5O7. The formulation can inhibit the dissolution of the aluminum alloy in the conversion liquid, is favorable for the deposition of Ce, and increases the deposition amount of Ce from 5.01% to 9.60%. The film prepared under the optimized formula is more uniform and dense with good electrochemical performance, corrosion potential increased by 0.13V, drip time up to 122 s. XRD and EDS results showed that the main component of the film is amorphous cerium or manganese oxide. |
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