Influence of Graphene on Microstructure and Corrosion and Wear Resistance of Micro-Arc Oxidation Coatings on D16T Al Alloy Drill Pipe

Abstract

Coatings were prepared on D16T Al alloy in electrolytes with and without graphene by micro-arc oxidation technology. Influences of graphene on the microstructure, corrosion and wear resistance of the coating were investigated. X-ray diffraction analysis result indicates that the coating is mainly composed of α-Al2O3, γ-Al2O3 and Al substrate. γ-Al2O3 was the dominant phase. The microstructure of coatings characterized by scanning electron microscopy, energy-dispersive x-ray spectroscopy and transmission electron microscopy shows the coating with graphene is flatter, denser, less pores and cracks than that of the coating without graphene. Moreover, the coating is consistent of a loose outer layer and dense inner layer. A little molten particles and many agglomerates accumulated on the surface of the coating. Graphene successfully embedded into the coating remarkedly decreased micro-pores and micro-cracks and slightly increased the thickness. The coating with graphene shows the better corrosion and wear resistance than the coating without graphene. The current potential, corrosion current density, wear and friction coefficient of coatings with graphene were − 0.41 V, 3.97E−8 A/cm2, 1.57 mg and 0.68, respectively, revealing the desirable corrosion and wear resistance. The presence of graphene in coatings improved the thickness and microstructure and increased the corrosion and wear resistance of the coating.