Corrosion Protection by Novel Conversion Coatings on Structural Al 6061

Main Article Content

Makanjuola Oki
Adeolu Adesoji Adediran
Anyim Ikechukwu
Charles O. Onokohwomo
Chuka Bosa
Sarah A. Akintola
Olanrewaju Seun Adesina


Chromate conversion coatings have witnessed limited acceptability in recent times. The coatings contain Cr (VI) species that have been classified as environmental hazards and injurious to human health. Thus, the use of environment-friendly and non-carcinogenic novel inorganic-inorganic hybrid conversion coatings are being explored. Vanadate (VCC), hybrid Vanadate/Molybdate (HCC) conversion coatings on Al6061 have been classified in terms of corrosion and adhesion performance with reference to the untreated alloy. Natural exposure tests in the atmosphere and stagnant near-neutral 3.5% sodium chloride solution, as well as potentio-dynamic polarization measurements showed that the corrosion rate for HCC is lower for Vanadate, which in turn outclassed the ‘bare’ alloy. However, clusters of passive incipient pits were revealed on the former after 120 h of exposure in stagnant chloride solution. Both conversion coatings outperformed the untreated aluminium alloy after atmospheric corrosion and adhesion tests.

Article Details

How to Cite
Oki, M., Adediran, A. A., Ikechukwu, A., Onokohwomo, C. O., Bosa, C., Akintola, S. A., & Adesina, O. S. (2022). Corrosion Protection by Novel Conversion Coatings on Structural Al 6061. Applied Science and Engineering Progress, 16(1), 5806.
Research Articles


M. Oki, A. A. Adediran, P. P. Ikubanni, O. S. Adesina, A. A. Adeleke, S. A. Akintola, F. Edoziuno, and A. Aleem, “Results in engineering corrosion rates of green novel hybrid conversion coating on aluminium 6061,” Results in Engineering, vol. 7, 2020, Art. no. 100159.

American Society for Testing and Materials, ASTM B449-93(2015), 2015.

G. Yoganandan, K. P. Premkumar, and J. N. Balaraju, “Evaluation of corrosion resistance and self-healing behavior of zirconium-cerium conversion coating developed on AA2024 alloy,” Surface and Coatings Technology, vol. 270, pp. 249–258, 2015.

I. Milošev and G. S. Frankel, “Review — conversion coatings based on zirconium and/or titanium,” Journal of the Electrochemical Society, vol. 165, no. 3, pp. C127–C144, 2018.

Z. Gao, D. Zhang, X. Li, S. Jiang, and Q. Zhang, “Current status, opportunities and challenges in chemical conversion coatings for zinc,” Colloids Surfaces A, vol. 546, pp. 221–236, 2018.

Z. Mahidashti, T. Shahrabi, and B. Ramezanzadeh, “Progress in organic coatings the role of posttreatment of an ecofriendly cerium nanostructure Conversion coating by green corrosion inhibitor on the adhesion and corrosion protection properties of the epoxy coating,” Progress in Organic Coatings, vol. 114, pp. 19–32, 2018.

J. J. Alba-Galvín, L. González-Rovira, F. J. Botana, M. Lekka, F. Andreatta, L. Fedrizzi, and M. Bethencourt, “Application of commercial surface pretreatments on the formation of cerium conversion coating (CeCC) over high-strength aluminum alloys 2024-T3 and 7075-T6,” Metals, vol. 11, no. 6, 2021, Art. no. 930.

A. E. Hughes and M. Resources, Conversion Coatings. Amsterdam, Netherlands: Elsevier, 2018.

J. Qi, L. Gao, Y. Li, Z. Wang, G. E. Thompson, and P. Skeldon, “An optimized trivalent chromium conversion coating process for AA2024-T351 alloy for AA2024-T351 alloy,” Journal of the Electrochemical Society, vol. 164, no. 7, pp. C390–C395, 2017.

M. Oki, A. A. Adediran, B. Ogunsemi, and O. Oluwole, “Improvement in corrosion resistance of aluminium alloy by permanganate-based conversion coating,” Journal of Physical Science, vol. 29, no. 2, pp. 13–24, 2018.

C. Liang, Z. Lv, Y. Zhu, S. Xu, and H. Wang, “Applied surface science protection of aluminium foil AA8021 by molybdate-based conversion coatings,” Applied Surface Science, vol. 288, pp. 497–502, 2014.

M. N. Solution, Š. Gavrilo, and I. Milo, “Electrochemical behavior and self-sealing ability of zirconium conversion coating applied on aluminum alloy 3005 in 0.5 M NaCl solution,” Journal of the Electrochemical Society, vol. 167, no. 2, 2020, Art. no. 021509.

B. Y. Shim, H. Kim, C. N. Han, Y. B. Jang, and J. W. Yun, “Characteristics of Cr (III) -based conversion coating solution to apply aluminum alloys for improving anti-corrosion properties,” Journal of the Microelectronics and Packaging Society, vol. 23, no. 4, pp. 79–85, 2016.

C. Cai, X.Q. Liu, X. Tan, G.D. Li, H. Wang, J. M. Li, and JJ. F. Li, “A Zr- and Cr (III) -containing conversion coating on Al alloy 2024-T3 and its self-repairing behavior,” Materials and Corrosion, vol. 68, no. 3, pp. 338-346, 2017.

J. T. Qi, T. Hashimoto, J. R. Walton, X. Zhou, P. Skeldon, and G. E. Thompson, “Trivalent chromium conversion coating formation on aluminium,” Surface and Coatings Technology, vol. 280, pp. 317–329, 2017

J. Qi, J. Swiatowska, P. Skeldon, and P. Marcus, “Chromium valence change in trivalent chromium conversion coatings on aluminium deposited under applied potentials,” Corrosion Science, vol. 167, 2020, Art. no. 108482.

T. G. Harvey, “Cerium-based conversion coatings on aluminium alloys : A process review Ceriumbased conversion coatings on aluminium alloys: A process review,” Corrosion Engineering, Science and Technology, vol. 48, pp. 248–269, 2013.

M. Oki and E. Charles, “Chromate conversion coating on Al–0.2 wt% Fe alloy,” Materials Letters, vol. 63, no. 23, pp. 1990–1991, 2009.

M. M. Kim, B. Kapun, U. Tiringer, G. Šekularac, and I. Milošev, “Protection of aluminum alloy 3003 in sodium chloride and simulated acid rain solutions by commercial conversion coatings containing Zr and Cr,” Coatings, vol. 9, no. 9, 2019, Art. no. 563.

A. Salam, I. Doench, and H. Möhwald, “Electrochimica acta assessment of a one-step intelligent self-healing vanadia protective coatings for magnesium alloys in corrosive media,” Electrochimica Acta, vol. 56, no. 5, pp. 2493–2502, 2011.

H. Guan and R. G. Buchheit, “Corrosion protection of aluminum alloy 2024-T3 by vanadate conversion coatings,” Corrosion, vol. 60, no. 3, pp. 284–296, 2004.

P. Wang, X. Dong, and D. W. Schaefer, “Structure and water-barrier properties of vanadate-based corrosion inhibitor films,” Corrosion Science, vol. 52, no. 3, pp. 943–949, 2010.

Z. Zou, N. Li, D. Li, H. Liu, and S. Mu, “A vanadium-based conversion coating as chromate replacement for electrogalvanized steel substrates,” Journal of Alloys and Compounds, vol. 509, no. 2, pp. 503–507, 2011.

Y. Ma, N. Li, D. Li, M. Zhang, and X. Huang, “Applied surface science characteristics and corrosion studies of vanadate conversion coating formed on,” Applied Surface Science, vol. 261, pp. 59–67, 2012.

G. Šekularac, J. Kovač, and I. Milošev, “Comparison of the electrochemical behaviour and self-sealing of zirconium conversion coatings applied on aluminium alloys of series 1xxx to 7xxx,” Journal of The Electrochemical Society, vol. 167, no. 11, 2020, Art. no. 111506.