Effects of nano-SiO2 and trivalent chromium conversion on corrosion resistance of NiZn-plated steel: towards a multilayer coating for steel protection
Anti-Corrosion Methods and Materials
ISSN: 0003-5599
Article publication date: 3 November 2022
Issue publication date: 2 January 2023
Abstract
Purpose
This study aims to enhance to corrosion protection of NiZn-plated steel by electroplating multilayer coating.
Design/methodology/approach
The multilayer coating consists of three layers on mild steel substrate, such as Cr3+ chromate conversion layer (CCC), electrodeposited nanosilica zinc-nickel composite layer (ZnNiSi) and electrodeposited zinc-nickel alloy layer (ZnNi). Its morphology, composition and corrosion behaviour were investigated by various methods.
Findings
Polarization curves indicated that polarization resistance and corrosion current density of CCC/ZnNiSi/ZnNi/Fe (6.956 kO.cm2; 2.56 µA.cm−2) were two times higher and five times lower than that of ZnNiSi/ZnNi/Fe (3.42 kO.cm2; 12.52 µA.cm−2), respectively. From electrochemical impedance spectroscopy data, charge transfer resistances were 1.344, 2.550 and 2.312 kO.cm2 for ZnNi, ZnNiSi/ZnNi and CCC/ZnNiSi/ZnNi, respectively. Salt spray test indicated that after 48 h, surface of ZnNi and ZnNiSi was covered by white rust, whereas no white rust was observed on surface of CCC/ZnNiSi/ZnNi. After 600 h, there were red rust spots (1% surface coverage) on surface of Zn-Ni, whereas only white rust was observed on both ZnNiSi/ZnNi (100% surface coverage) and CCC/ZnNiSi/ZnNi (10% surface coverage).
Originality/value
Multilayer coating enhanced significantly the corrosion protection for steel, as compared to the single-layer coating.
Keywords
Acknowledgements
Funding: This work was financially supported by the Department of Science and Technology of Ho Chi Minh City (project No. 101/2020/H-DQPTKHCN, Thi Thanh Huong Nguyen). Additional financial resource for short visit from Vietnam Academy of Science and Technology and Bulgarian Academy of Sciences (Project No. QTBG01.02/20–21, Nam Pham Thi) is also acknowledged.
Citation
Nguyen, T.T.H., Pham Thi, N., Le Ba, T., Uong Van, V., Le Duc, B. and Nguyen, T.A. (2023), "Effects of nano-SiO2 and trivalent chromium conversion on corrosion resistance of NiZn-plated steel: towards a multilayer coating for steel protection", Anti-Corrosion Methods and Materials, Vol. 70 No. 1, pp. 1-8. https://doi.org/10.1108/ACMM-08-2022-2691
Publisher
:Emerald Publishing Limited
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