Microstructure, wear and corrosion performance of plasma electrolytic oxidation coatings formed on D16T Al alloy


The plasma electrolytic oxidation (PEO) coatings were produced on D16T Al alloy in the aluminate and silicate electrolyte with and without graphene. The phase composition, microstructure and elemental distribution of the coatings were tested by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). The wear and corrosion resistance of PEO coatings were evaluated by dry sliding wear tests and electrochemical impedance spectroscopy (EIS). The morphology feature of the wear tracks was compared and analyzed by SEM and three-dimensional microscope. The results demonstrate that the structure, wear and corrosion resistance of PEO coatings with graphene are better than that of PEO coatings without graphene. The coating fabricated in the aluminate electrolyte with graphene exhibited the lowest roughness. The coated samples formed in silicate electrolyte with graphene displayed the thickest, densest and the most compact coating. It exhibited the best wear and corrosion resistance due to the incorporation mode of graphene in the coatings. The mechanism of graphene improving the wear and corrosion resistance of PEO coating was further discussed. In summary, the comprehensive performances of PEO coatings formed in silicate electrolyte on D16T Al alloy are superior to that produced in aluminate electrolyte.
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