| CUI Shan,AN Cheng-qiang,HAO Jian-jun.Research Progress in Chromium-free Passivaton of Aluminium and Aluminium Alloy[J],45(6):63-69 |
| Research Progress in Chromium-free Passivaton of Aluminium and Aluminium Alloy |
| Received:March 22, 2016 Revised:June 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.06.010 |
| KeyWord:aluminium and aluminium alloy chromium-free passivation corrosion resistance silane composite film |
| Author | Institution |
| CUI Shan |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
| AN Cheng-qiang |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
| HAO Jian-jun |
School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang , China |
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| Abstract: |
| Aluminum alloy can be processed into a variety of sheets, profiles and aluminum casting. Passivation of aluminum alloy is required in order to reduce its corrosion damage in the industrial environment. Passivation is often used as a coating pretreatment step and the passivate film can enhance the adhesion strength between the aluminum alloy surface and the organic coating, further improving the protection ability of coating. At present, chromium-free passivation mainly includes molybdate passivation, rare earth salt passivation, zirconium/titanium salt passivation and organic passivation. In this paper, the research process and current situation of these main chemical passivation methods were summarized. Compounding of molybdate with other salts results in enhanced inhibition of corrosion leading to stronger corrosion resistance. Addition of strong oxidizer and film-forming promoter into rare earth salts can simplify the process and reduce the corrosion current. Adding organic matter to Zirconium and titanium salts to form composite films can improve the corrosion resistance of the single film layer and can improve the binding force with the matrix. Silane forms a crosslinking structure on the aluminum alloy surface, and showed a good sealing effect. Adding nanoparticles into silane can obtain better film surface morphology, whereas adding rare earth and its oxides can improve the corrosion resistance. Altering the film forming order in the silane two-step film-forming process can get different membrane layer physical properties and corrosion resistance. Finally, the future research direction of chromium-free passivation technology was prospected. |
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