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Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel

[Image: see text] Phosphate- or chromate-based industrially produced conversion layers, while effectively increasing adhesion for organic coatings and corrosion resistance, come at the cost of environmentally problematic and harmful treatment solutions and waste. In this respect, layered double hydr...

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Autores principales: Holzner, Tobias, Luckeneder, Gerald, Strauß, Bernhard, Valtiner, Markus
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2022
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8815042/
https://www.ncbi.nlm.nih.gov/pubmed/35050563
http://dx.doi.org/10.1021/acsami.1c19573
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author Holzner, Tobias
Luckeneder, Gerald
Strauß, Bernhard
Valtiner, Markus
author_facet Holzner, Tobias
Luckeneder, Gerald
Strauß, Bernhard
Valtiner, Markus
author_sort Holzner, Tobias
collection PubMed
description [Image: see text] Phosphate- or chromate-based industrially produced conversion layers, while effectively increasing adhesion for organic coatings and corrosion resistance, come at the cost of environmentally problematic and harmful treatment solutions and waste. In this respect, layered double hydroxide (LDH)-based conversion layers offer an environmentally benign alternative without toxicologically concerning compounds in the treatment solution. Here, we study an LDH conversion layer on Zn–Al–Mg-coated steel (ZM-coated steel), which was produced by immersion into a carbonate- and magnesium-containing alkaline solution. The mechanism and kinetics of the conversion layer formation were investigated with in situ open circuit potential measurements, cyclic voltammetry (CV), and scanning electron microscopy (SEM). Acceleration of the LDH layer formation through high convection in the treatment solution was found. This was attributed to a higher oxygen availability at the metal/solution interface because no diffusion-limited state during the layer formation is reached due to high convection. The importance of oxygen within the kinetics indicates a corrosion-like mechanism, with cathodic and anodic sites on the steel sample. The LDH formation happens by co-precipitation of ions present in the treatment solution and dissolved ions from the ZM-coated steel. With CV, SEM, and X-ray diffraction, the growth of the LDH conversion layer was investigated with respect to the immersion time. It was found that after 30 s, the sample surface was almost fully covered with an LDH layer, and with the increasing immersion time, the layer grows in thickness. Increased understanding on the kinetics and mechanism of the LDH conversion layer formation on ZM-coated steel gives rise to a targeted optimization of the treatment solution and process parameters.
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spelling pubmed-88150422022-02-07 Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel Holzner, Tobias Luckeneder, Gerald Strauß, Bernhard Valtiner, Markus ACS Appl Mater Interfaces [Image: see text] Phosphate- or chromate-based industrially produced conversion layers, while effectively increasing adhesion for organic coatings and corrosion resistance, come at the cost of environmentally problematic and harmful treatment solutions and waste. In this respect, layered double hydroxide (LDH)-based conversion layers offer an environmentally benign alternative without toxicologically concerning compounds in the treatment solution. Here, we study an LDH conversion layer on Zn–Al–Mg-coated steel (ZM-coated steel), which was produced by immersion into a carbonate- and magnesium-containing alkaline solution. The mechanism and kinetics of the conversion layer formation were investigated with in situ open circuit potential measurements, cyclic voltammetry (CV), and scanning electron microscopy (SEM). Acceleration of the LDH layer formation through high convection in the treatment solution was found. This was attributed to a higher oxygen availability at the metal/solution interface because no diffusion-limited state during the layer formation is reached due to high convection. The importance of oxygen within the kinetics indicates a corrosion-like mechanism, with cathodic and anodic sites on the steel sample. The LDH formation happens by co-precipitation of ions present in the treatment solution and dissolved ions from the ZM-coated steel. With CV, SEM, and X-ray diffraction, the growth of the LDH conversion layer was investigated with respect to the immersion time. It was found that after 30 s, the sample surface was almost fully covered with an LDH layer, and with the increasing immersion time, the layer grows in thickness. Increased understanding on the kinetics and mechanism of the LDH conversion layer formation on ZM-coated steel gives rise to a targeted optimization of the treatment solution and process parameters. American Chemical Society 2022-01-20 2022-02-02 /pmc/articles/PMC8815042/ /pubmed/35050563 http://dx.doi.org/10.1021/acsami.1c19573 Text en © 2022 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Holzner, Tobias
Luckeneder, Gerald
Strauß, Bernhard
Valtiner, Markus
Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel
title Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel
title_full Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel
title_fullStr Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel
title_full_unstemmed Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel
title_short Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel
title_sort environmentally friendly layered double hydroxide conversion layers: formation kinetics on zn–al–mg-coated steel
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8815042/
https://www.ncbi.nlm.nih.gov/pubmed/35050563
http://dx.doi.org/10.1021/acsami.1c19573
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