The influence of different types of epoxy resins on protection performance of magnesium-rich coating for AZ91D alloy was studied with scratch testing

electrochemical impedance spectroscopy (EIS)

open circuit potential (OCP) and dynamic potential scanning. The results indicated that Mg-rich coating consisting of epoxy coating 618-593 showed poor protective performance. Magnesium particles in 6101-TY650 epoxy coating could significantly improve the protective effect for magnesium alloy substrate at the coating defects

however

their over the long-term protection performance was poor. Epoxy 618-T31 coating showed strong barrier properties. Then

the Mg-rich primer consisting of epoxy coating 618-T31 had a strong protective effect

indicating that the epoxy coating 618-T31 was suitable for the preparation of Mg-rich coating for AZ91D alloy. For AZ91D alloy

magnesium particles added in three types of epoxy coatings could provide cathodic protection to AZ91D substrate at coatings defects

prolonging the corrosion life of coatings. Meanwhile

magnesium particles were activated to provide cathodic protection for the magnesium alloy substrate to some extent

retarding the corrosion rate of magnesium alloy substrate.