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Enhancing the corrosion resistance of plasma electrolytic oxidation coatings by plasticizing chitosan films with glycerol.

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Title: Enhancing the corrosion resistance of plasma electrolytic oxidation coatings by plasticizing chitosan films with glycerol.
Authors: Li, Yang1,2 (AUTHOR), Yang, Shuyan1 (AUTHOR) yangshuyan@qut.edu.cn, Wan, Yong1,2,3 (AUTHOR) wanyong@qlu.edu.cn
Source: Ceramics International. Aug2025:Part A, Vol. 51 Issue 20, p30394-30404. 11p.
Subject Terms: *COMPOSITE coating, *ELECTROLYTIC oxidation, *CORROSION resistance, *INTERMOLECULAR forces, *ALUMINUM alloys
Abstract: This study explores the enhancement of corrosion resistance in plasma electrolytic oxidation (PEO) coatings on aluminum alloys through the integration of glycerol (Gly)-plasticized chitosan (CS) films. A dual-layer composite coating system was developed via a dipping-pulling technique, combining a ceramic PEO base layer with a flexible Gly-modified CS top film. By systematically varying Gly concentrations (0–200 % relative to CS mass), the interplay between Gly-induced structural modifications in the CS film and the resulting electrochemical performance was investigated. Fourier-transform infrared spectroscopy (FTIR) and microstructural analyses revealed that Gly interacts with CS via hydrogen bonding, disrupting native intermolecular forces and enhancing film flexibility. This plasticization effect promoted thicker, more uniform CS layers, with thickness increasing from 2.7 ± 0.3 μm (Gly-0 %) to 16.5 ± 1.7 μm (Gly-200 %). Electrochemical characterization demonstrated a strong concentration-dependent anticorrosion behavior of the composite coatings. At moderate Gly concentrations, the Gly-50 % coating achieved an optimal balance among film thickness, porosity, and mechanical properties. Compared to the unmodified Gly-0 % coating, this balanced formulation reduced corrosion current density by two orders of magnitude. Long-term immersion tests further revealed that the Gly-50 % coating retained over 85 % of its initial impedance modulus after 7 days in 3.5 wt % NaCl solution, highlighting exceptional durability. However, both insufficient and excessive Gly concentrations induced increased coating porosity, consequently diminishing corrosion protection performance. The study highlights the significance of glycerol concentration optimization in designing robust, eco-friendly chitosan-based composite coatings, presenting promising potential for advanced corrosion-resistant applications. [ABSTRACT FROM AUTHOR]
Database: Academic Search Index
Description
Abstract:This study explores the enhancement of corrosion resistance in plasma electrolytic oxidation (PEO) coatings on aluminum alloys through the integration of glycerol (Gly)-plasticized chitosan (CS) films. A dual-layer composite coating system was developed via a dipping-pulling technique, combining a ceramic PEO base layer with a flexible Gly-modified CS top film. By systematically varying Gly concentrations (0–200 % relative to CS mass), the interplay between Gly-induced structural modifications in the CS film and the resulting electrochemical performance was investigated. Fourier-transform infrared spectroscopy (FTIR) and microstructural analyses revealed that Gly interacts with CS via hydrogen bonding, disrupting native intermolecular forces and enhancing film flexibility. This plasticization effect promoted thicker, more uniform CS layers, with thickness increasing from 2.7 ± 0.3 μm (Gly-0 %) to 16.5 ± 1.7 μm (Gly-200 %). Electrochemical characterization demonstrated a strong concentration-dependent anticorrosion behavior of the composite coatings. At moderate Gly concentrations, the Gly-50 % coating achieved an optimal balance among film thickness, porosity, and mechanical properties. Compared to the unmodified Gly-0 % coating, this balanced formulation reduced corrosion current density by two orders of magnitude. Long-term immersion tests further revealed that the Gly-50 % coating retained over 85 % of its initial impedance modulus after 7 days in 3.5 wt % NaCl solution, highlighting exceptional durability. However, both insufficient and excessive Gly concentrations induced increased coating porosity, consequently diminishing corrosion protection performance. The study highlights the significance of glycerol concentration optimization in designing robust, eco-friendly chitosan-based composite coatings, presenting promising potential for advanced corrosion-resistant applications. [ABSTRACT FROM AUTHOR]
ISSN:02728842
DOI:10.1016/j.ceramint.2025.04.233