Towards development of anticorrosive CaCO3-coated passive layer on Mg alloy with ultrasound-assisted electrodeposition

An anticorrosive CaCO3-coated Mg(Al)O passive layer was obtained via the ultrasound-assisted electrodeposition on AZ41 Mg alloy for concrete formwork. Corrosion rate of the CaCO3/Mg(Al)O coated AZ41 Mg alloy was lower than 0.005 mmy  1 in Portland cement (PC) system containing 0.6 M NaCl. Ultrasound plays a dual-role in forming a dense Mg(Al)O passivation film and densifying the outer CaCO3 layer. Furthermore, re-passivation instead of corrosion was observed during the embedment, attributed to the double-layer structure effectively increasing the critical chloride ion concentration for corrosion. Formation and anticorrosion mechanism as well as the role of the passivation film in anticorrosion are discussed.

Automated summary

An anticorrosive CaCO3-coated Mg(Al)O passive layer was successfully obtained on AZ41 Mg alloy through ultrasound-assisted electrodeposition, which exhibited a low corrosion rate in concrete formwork and improved corrosion resistance through its double-layer structure.