Effect of surface treatments on the localized corrosion resistance of the AA2198-T8 aluminum lithium alloy welded by FSW process |
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Authors: | Caruline de S. C. Machado Rafael E. Klumpp Victor H. Ayusso Uyime Donatus Mariana X. Milagre João V. de S. Araujo Glauson A. F. Machado I. Costa |
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Affiliation: | Instituto de Pesquisas Energéticas e Nucleares–IPEN/CNEN, São Paulo, Brazil |
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Abstract: | In this work, the effect of eight types of surface treatments on the corrosion resistance of friction stir welded samples of an AA2198-T8 Al-Cu-Li alloy were tested and compared in an attempt to find suitable alternatives to toxic and carcinogenic hexavalent chromium treatments. All the samples were anodized and subjected to different post-anodizing treatments. The post-anodizing treatments were (1) hydrothermal treatment in Ce (NO3)3 6H2O solution; (2) hydrothermal treatment in Ce (NO3)3 6H2O solution with H2O2; (3) hydrothermal treatment in boiling water; (4) hexavalent chromium conversion coating; and (5) immersion in BTSE (bis-1,2-(triethoxysilyl) ethane. The corrosion resistance of the treated samples was evaluated by immersion tests in sodium chloride solution (0.1 mol L−1 NaCl) and electrochemical impedance spectroscopy (EIS) of the friction stir weldment. The results showed that among the alternative treatments, the Ce-containing solutions presented the best corrosion resistance, especially when used without peroxide. |
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Keywords: | AA2198-T8 corrosion protection friction stir welding post-anodizing treatments |
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