Enhancing surface protection of Mg alloy concrete formwork: Magnesium carbonate-based coatings under varied pH conditions via ultrasonic-cavitated chemical conversion

Abstract

Improving the anticorrosion property of Mg alloys used as concrete formwork is essential for extending their lifespan and ensuring structural integrity. Therefore, MgCO3·3H2O + MgCO3·Mg(OH)2·3H2O/MgO composite coating was prepared on AZ41 Mg alloys using an ultrasonic-cavitated chemical conversion method under different pH conditions. Electrochemical methods combined with immersion tests in the simulated concrete pore solutions containing 0.6 M NaCl were adopted to assess the anticorrosion performance of the uncoated and coated specimens. Results indicate that the improved pH benefits the densification of the composite coating, thus leading to the enhanced anticorrosion performance. The generation of dense MgCO3·Mg(OH)2·3H2O layer rather than corrosion products after immersion makes such an affordable anticorrosion coating, amenable to large-scale production, holds promise as a viable surface treatment method for Mg alloy concrete formwork.

Keywords

• Magnesium alloy
• Concrete formwork
• Corrosion resistance
• Magnesium carbonate hydroxide
• Ultrasound
• Chemical conversion