Improved corrosion and wear resistance of micro-arc oxidation coatings on the 2024 aluminum alloy by incorporation of quasi-two-dimensional sericite microplates

Abstract

Although aluminum alloys are widely used in the aerospace and automotive industry, they are susceptible to local corrosion and wear during long-term service in harsh environment. In this work, micro-arc oxidation (MAO) coatings containing quasi-2D sericite microplates are prepared on the 2024 aluminum alloy, and their corrosion and wear resistance are investigated. The results reveal that the sericite-incorporated MAO sample prepared in the 15 g/L sericite electrolyte (M−15) possesses the best corrosion resistance in 3.5 wt% NaCl solution, as manifested by a corrosion current density of 2.93 × 10−10 A ∗ cm−2 that is 4 orders of magnitude less than that of the 2024 Al alloy substrate. The wear resistance of MAO coating is also improved by the addition of sericite microplates, which is shown by the low wear rate and reduced coefficient of friction (∼0.3) of M−15 against steel ball. Our mechanistic study reveals that the quasi-2D sericite microplates in the coatings can prevent the penetration of the corrosive media and facilitate the formation of the tribo-transfer film. The sericite-containing MAO coatings providing excellent protection to aluminum alloys under corrosion and wear conditions possess great application prospects and large commercial potential.