Impact of Bi and Sn on Microstructure and Corrosion Resistance of Zinc Coatings Obtained in Zn-AlNi Bath

The paper presents results of studies on the impact of bismuth and tin additions to the Zn-AlNi bath on microstructure and corrosion resistance of hot dip galvanizig coatings. The structure at high magnifications on the top surface and cross-section of coatings received in the Zn-AlNiBiSn bath was r...

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Bibliographic Details
Published in:Materials 2020-08, Vol.13 (17), p.3788
Main Authors: Kania, Henryk, Saternus, Mariola, Kudláček, Jan
Format: Article
Language:English
Subjects:
Bismuth base alloys
Chemical composition
Corrosion cell
Corrosion resistance
Corrosion tests
Dip coatings
Electropositivity
Galvanized steel
Hot dip galvanizing
Hot dipping
Microstructure
Oxidation
Protective coatings
Salt spray tests
Tin
Zinc
Zinc coatings
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Summary:The paper presents results of studies on the impact of bismuth and tin additions to the Zn-AlNi bath on microstructure and corrosion resistance of hot dip galvanizig coatings. The structure at high magnifications on the top surface and cross-section of coatings received in the Zn-AlNiBiSn bath was revealed and the microanalysis EDS (energy dispersion spectroscopy) of chemical composition was determined. The corrosion resistance of the coatings was tested relatively in a neutral salt spray test (NSS), and tests in a humid atmosphere containing SO2. Electrochemical parameters of coatings corrosion were determined. It was found that Zn-AlNiBiSn coatings show lower corrosion resistance in comparison with the coatings received in the Zn-AlNi bath without Sn and Bi alloying additions. Structural research has shown the existence of precipitations of Sn-Bi alloy in the coating. It was found that Sn-Bi precipitations have more electropositive potential in relation to zinc, which promotes the formation of additional corrosion cells.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma13173788