Journal
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
Volume 666, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.colsurfa.2023.131283
Keywords
Dopamine; Mg alloys; Corrosion; Sol-gel; Corrosion protection
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Magnesium alloys have excellent mechanical and physical properties, but their poor corrosion resistance hampers their application in aqueous and atmospheric environments. To address this issue, a new sol-gel coating using polydopamine was developed, which significantly improved the corrosion protection performance of magnesium alloy AZ31. This coating demonstrated enhanced durability and provided long-term corrosion protection for over 20 days in an aqueous NaCl solution, compared to unmodified coatings that failed after only 3 days of immersion.
Mg alloys have excellent mechanical and physical properties. Unfortunately, the poor corrosion resistance be -comes the main disadvantage of the application of such materials in aqueous and atmospheric media. Although the sol-gel-based coating has attracted significant attention for alloys in corrosion protection, most of the existing sol-gel coatings are unable to give a long-term protection for the substrate against corrosion in saline solutions due to micro-/ nano-pores contained in its glassy sol-gel networks. To address this issue, a new sol-gel coating was prepared by utilizing the strong adhesion property of polydopamine (PDA) to provide a highly condensed sol-gel-based coating (PDA@sol-gel) on Mg alloy AZ31. Long-term corrosion testing by electrochemical impedance spectroscopy in aqueous 0.1 M NaCl indicated that the prepared PDA@sol-gel coating exhibited a substantially improved corrosion protection performance with a test duration of over 20 days. In comparison, the unmodified coating failed after 3 days of immersion in aqueous NaCl. The improved anti-corrosion performance may be attributed to the self-polymerized PDA filling the micro-/ nano defects in the cross-linked network of the SiO2 sol-gel, which greatly improves the compactness of the coating. This work presented a new approach to significantly improve the corrosion protection performance of magnesium alloys by dopamine-modified sol-gel coating, which can find ample applications in a wide range of industries.
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