Microstructure, phase evolution and corrosion behaviour of the Zn–Al–Mg–Sb alloy coating on steel

Tat, L. Hai; Bakhsheshi‐Rad, Hamid Reza; Hamzah, Esah; Cho, M.H.; Mostafa, Ahmad; Farahany, Saeed

doi:10.1080/02670836.2019.1705587

Cited by 12 publications

(4 citation statements)

References 40 publications

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“…Previous studies have focused on the MgZn 2 phase within Zn-Al-Mg coatings, considered a crucial factor in enhancing these coatings’ corrosion resistance [ 3 , 12 , 13 ]. However, as research progresses, some studies have also identified the presence of the Mg 2 Zn 11 phase, indicating that the phase composition of these coatings is more complex than expected [ 8 , 14 , 15 , 16 , 17 ]. These findings have sparked the need for a deeper exploration of the phase transformation mechanisms occurring within these coatings, especially the transformation from MgZn 2 to Mg 2 Zn 11 and its specific impact on coating performance.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Simulation Calculations of Phase Transformations in Low-Aluminum Zn-Al-Mg Coatings

Zhang,

Zhao

et al. 2024

Materials

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This study delves into the formation, transformation, and impact on coating performance of MgZn2 and Mg2Zn11 phases in low-aluminum Zn-Al-Mg alloy coatings, combining thermodynamic simulation calculations with experimental verification methods. A thermodynamic database for the Zn-Al-Mg ternary system was established using the CALPHAD method, and this alloy’s non-equilibrium solidification process was simulated using the Scheil model to predict phase compositions under varying cooling rates and coating thicknesses. The simulation results suggest that the Mg2Zn11 phase might predominate in coatings under simulated production-line conditions. However, experimental results characterized using XRD phase analysis show that the MgZn2 phase is the main phase existing in actual coatings, highlighting the complexity of the non-equilibrium solidification process and the decisive effect of experimental conditions on the final phase composition. Further experiments confirmed that cooling rate and coating thickness significantly influence phase composition, with faster cooling and thinner coatings favoring the formation of the metastable phase MgZn2.

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Section: Introductionmentioning

confidence: 99%

Thermodynamic Simulation Calculations of Phase Transformations in Low-Aluminum Zn-Al-Mg Coatings

Zhang,

Zhao

et al. 2024

Materials

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“…The performance of zinc-aluminummagnesium coating products mainly depends on the phase composition and microstructure, and the typical structures include a Zn-rich phase (a spherical and platy structure), a binary Zn/MgZn 2 eutectic phase (a coarse platy structure), and a ternary Zn/MgZn 2 /Al eutectic phase (a fine platy structure). Studies have shown that the MgZn 2 phase is the main reason for the improved corrosion resistance of a coating [9][10][11][12]. During the corrosion process, an electric couple is formed between Zn and MgZn 2 due to the potential difference between them.…”

Section: Introductionmentioning

confidence: 99%

Effect of Al/Mg Ratio on the Microstructure and Phase Distribution of Zn-Al-Mg Coatings

Zhang,

Zhao

et al. 2023

Metals

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In contrast with studies such as those on the effect of a single elemental variable on Zn-Al-Mg coatings, Mg/Al is considered a variable parameter for evaluating the microstructure of Zn-Al-Mg coatings in this work, and the combined effect of the two elements is also taken into account. The Mg/Al ratios in the continuous hot-dip plating of low-alumina Zn-Al-Mg coatings were 0.63, 0.75, 1.00, 1.25, and 1.63. respectively, and the microstructures of the different coatings were observed using scanning electron microscopy (SEM). The surface elemental distributions of the coatings were analyzed with energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) analysis to understand the phase distributions of the coatings, which mainly consisted of a zinc monomeric phase, a binary eutectic phase (Zn/MgZn2), and a ternary eutectic phase (Zn/Al/MgZn2). Statistical calculations of the phase distributions in colored SEM images were performed using ImageJ-win64 software, comparative analysis of the solidification simulation results was carried out with thermodynamic simulation software (PANDAT-2023), and evaluation of the corrosion resistance of the platings was performed using macroscopic cyclic immersion corrosion experiments. The results show that with the increase in the Mg/Al ratio, the binary eutectic phase in the coatings gradually increased, the variation trend of the ternary eutectic phase was not obvious, and the corrosion resistance of the coatings gradually improved.

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“…As environmental conditions become increasingly complex, the requirements for corrosion-resistant Zn coatings are increasing and the galvanizing technology is gradually advancing toward the development of multi-alloy coatings. The corrosion resistance of Zn coatings was improved greatly by adding a certain proportion of Al and Mg [5][6][7]. Dense areas, such as Zn/Al/MgZn 2 ternary eutectic structures, were produced in the Zn-Al-Mg coating [8][9][10], which played a very important role during the corrosion process.…”

Section: Introductionmentioning

confidence: 99%

Wetting of liquid Zinc-aluminum-magnesium alloy on steel substrate during hot-dipping: Understanding the role of the flux

Zheng

Han

et al. 2022

Surf. Topogr.: Metrol. Prop.

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The surface quality of hot-dipping Zn-Al-Mg coatings was significantly influenced by the composition of fluxes. In this study, five different fluxes were chosen and named as F1 (ZnCl2, NH4Cl), F2 (ZnCl2, NaF), F3 (ZnCl2, NH4Cl, KCl), F4 (ZnCl2, NH4Cl, KCl, SnCl2, HCl), and F5 (ZnCl2, NH4Cl, KCl, BiCl3, HCl). Using the sessile drop method, the influence of different fluxes on the wettability between the liquid Zn-Al-Mg alloy and the steel substrate was elucidated. The results showed that: when the flux composition is ZnCl2-NH4Cl-KCl-BiCl3-HCl, a uniform and dense salt film with a protective effect can be formed on the steel substrate, which prevents the oxidation of the steel substrate and removes the harmful reaction products during hot-dipping. By reducing the solid–liquid interface energy, increasing the work of adhesion between the liquid Zn-6Al-3Mg alloy and steel substrate, and shortening the interface reaction time, the strongest wetting effect between the liquid Zn-6Al-3Mg alloy and the steel substrate was achieved. The coating surface quality was the highest after using the F5 flux. Finally, the mechanism of the assistant plating is discussed.

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Microstructure, phase evolution and corrosion behaviour of the Zn–Al–Mg–Sb alloy coating on steel

Cited by 12 publications

References 40 publications

Thermodynamic Simulation Calculations of Phase Transformations in Low-Aluminum Zn-Al-Mg Coatings

Thermodynamic Simulation Calculations of Phase Transformations in Low-Aluminum Zn-Al-Mg Coatings

Effect of Al/Mg Ratio on the Microstructure and Phase Distribution of Zn-Al-Mg Coatings

Wetting of liquid Zinc-aluminum-magnesium alloy on steel substrate during hot-dipping: Understanding the role of the flux

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