| CHEN Yue-liang,ZHANG Yang-guang,BIAN Gui-xue,ZHANG Yong,ZHANG Zhu-zhu.Electrochemical Evolution of 2A12 Aluminum Alloy with Different Anodic Films in NaCl Solution[J],49(9):348-356 |
| Electrochemical Evolution of 2A12 Aluminum Alloy with Different Anodic Films in NaCl Solution |
| Received:December 01, 2019 Revised:September 20, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2020.09.040 |
| KeyWord:aluminum alloy anodizing sealing EIS equivalent circuit electrochemical evolution Warburg impedance |
| Author | Institution |
| CHEN Yue-liang |
1.Naval Aviation University Qingdao Campus, Qingdao , China |
| ZHANG Yang-guang |
1.Naval Aviation University Qingdao Campus, Qingdao , China; 2.The 32102 Unit of PLA, Yantai , China |
| BIAN Gui-xue |
1.Naval Aviation University Qingdao Campus, Qingdao , China |
| ZHANG Yong |
1.Naval Aviation University Qingdao Campus, Qingdao , China |
| ZHANG Zhu-zhu |
1.Naval Aviation University Qingdao Campus, Qingdao , China |
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| Abstract: |
| The work aims to evaluate the corrosion electrochemical evolution behavior of 2A12 aluminum alloy with different anodic films under the action of chloride ions. The dichromate sealed sulfuric acid anodizing (DS-SAA) film, hot water sealed sulfuric acid anodizing (HWS-SAA) film and dilute chromic acid sealed chromic acid anodizing (DCS-CAA) film were prepared on 2A12 aluminum alloy. Potentiodynamic polarization and electrochemical impedance characterization and fitting, combined with stereoscopic microscope, were used to analyze the change of electrochemical parameters of different oxide film samples with immersion time in 3.5% NaCl solution and discuss the evolution law and mechanism of film layer. The thickness of SAA film and CAA film was about 8 μm and 3 μm respectively, and the surface defects of the latter were less. After immersion in NaCl solution for 1 hour, the corrosion current density of DS-SAA, HWS-SAA, and DCS-CAA samples were 9.1, 0.86 and 12.9 nA/cm2, respectively. After 168 hours of immersion, the corrosion current density of DS-SAA, HWS-SAA, and DCS-CAA samples increased to 15.5, 35.3 and 2628 nA/cm2, respectively. The corrosion potential of DS-SAA samples increased by 205 mV, and that of DCS-CAA samples decreased from -604 mV to -930 mV. With the increase of immersion time, the Rb and Rp values of DS-SAA were higher than 107 and 105 Ω•cm2. After immersion for 24 hours, Warburg impedance appeared in impedance spectra of HWS-SAA and DCS-CAA specimens, and Rb and Rp values decreased rapidly. The corrosion resistance of the three kinds of oxide films is equal at the initial stage of immersion. With the extension of time, the dichromate sealed sulfuric acid anodizing (DS-SAA) film has higher corrosion resistance and durability, while the corrosion resistance of the other two kinds of oxide films decreases rapidly, and the porous layer almost completely fails after 168 hours. The difference of corrosion resistance of anodic film is related to film thickness and sealing mechanism. |
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