Effect of lanthanum addition on microstructures and corrosion behavior of ZnAl-LDHs film of 6061 aluminum alloys

• Published in: Surface & coatings technology 2019-12, Vol.379, p.125056, Article 125056
• Main Authors: Zhou, Bingtao, Wei, Xiaofeng, Wang, Youbin, Huang, Qiuyu, Hong, Biao, Wei, Yuezhou
• Format: Article
• Language: English
• Subjects: Aluminum alloys; Corrosion behavior; Lanthanum; Microstructures; ZnAl-LDHs
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.125056

ZnAl-LDHs and ZnLaAl-LDHs films were fabricated on the surface of 6061 aluminum alloys using in-situ growth method. The microstructures of LDHs films were investigated through the X-ray diffraction (XRD), scanning electronic microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that ZnAl-LDHs and ZnLaAl-LDHs nanosheets grow up perpendicular to the surface of the aluminum substrate. It is noteworthy that, the nanosheet of ZnLaAl-LDHs is more fine and dense than that of ZnAl-LDHs under the same growth condition. On the other hand, addition of lanthanum ions inhibit the growth rate of the ZnAl-LDHs nanosheet. The corrosion performance of the ZnAl-LDHs and ZnLaAl-LDHs films were analyzed through the polarization curves and electrochemical impedance spectroscopy (EIS). LDHs films enhance the corrosion resistance of 6061 aluminum alloys, and the corrosion protection performance of LDHs films are improved as the growth time increase. Furthermore, lanthanum addition enhances the anti-corrosion performance of the ZnAl-LDHs film. Comparison of the corrosion resistance properties of both films; it was found that ZnLaAl-LDH film has high ratio than ZnAl-LDHs by 24%, 42%, 160% and 210% for the growth time 15 min, 1 h, 4 h and 8 h, respectively. Finally, the formation and corrosion mechanism of ZnLaAl-LDHs film on 6061 aluminum alloys are discussed in detail. [Display omitted] •ZnLaAl-LDHs film was prepared on 6061 aluminum alloy using in-situ growth method.•Doping lanthanum improve the compactness of LDHs films and inhibits the LDHs growth.•Lanthanum addition enhance the corrosion resistance of ZnAl-LDHs film.•The formation and corrosion mechanism of ZnLaAl-LDHs film were discussed in detail.