Corrosion behavior of AA 6061 alloy anodized with addition of a rare earth (cerium) compound in NaCl solution

• G. Priyotomo¹, Y. Lestari¹, M. Marisa², S. Bahtiar², J. Triwardono¹, A. Nikitasari¹, R. Kusumastuti¹, S. Prifiharni¹ and S. Musabhika¹

¹ Research Center for Metallurgy and Material, National Research and Innovation Agency, Building 470, Puspiptek, Tangerang Selatan, Banten, 15314, Indonesia
² Metallurgy Engineering Department, University of Sumbawa Technology, Jl. Raya Olat Maras, Batu Alang, Moyo Hulu, Sumbawa Regency, NTB, 84371, Indonesia

Abstract: Anodizing techniques are used to treat aluminum alloys electrochemically in order to increase their resistance to corrosion. The anodizing process on AA6061 alloy was performed in sulfuric acid solutions for 30 min and 60 min with continuous stirring at a fixed current of 5 A. After anodizing, a 60 min sealing procedure in water at 95°C was conducted. Cerium-containing coatings were formed on the alumunium alloy anodized in mixed solutions (Ce(NO₃)₃·6H₂O and C₆H₁₂N₄) with various molar ratios of 1:3, 2:3, 3:3, 3:2, and 3:1. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) measurements were used to characterize the microstructure and provided qualitative and quantitative data on the elemental composition. Electrochemical studies were carried out using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. The wetting properties of the cerium-containing coating were analyzed using water contact angle measurement. The results show that the corrosion resistance of cerium coated AA6061 increase compared to uncoated ones in all the parameters. The highest corrosion resistance of cerium coated AA6061 was obtained at a molar ratio of 3:3 for all the anodizing process times. The EIS results show an increase in corrosion resistance for cerium coated anodized aluminum. The presence of a homogenous cerium-based coating on anodized AA6061 inhibits the penetration of aggressive Cl ions into the nano pore layer of the substrates. Overall, the anodizing results showed that the cerium sealed aluminum surfaces has hydrophilic properties.

Keywords: aluminum alloy, anodizing, corrosion, electrochemical test, potentiodynamic polarization, sodium chloride

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1130-1143
doi: 10.17675/2305-6894-2025-14-3-7

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