Microstructure, deposition mechanism and tribological performance of graphene oxide reinforced Fe composite coatings by electro-brush plating technique

Enhancement of mechanical performances is a challenging issue for Fe-based coatings prepared by electro-brush plating technique (EBP), and graphene oxide (GO) has been regarded as a promising additive currently. Thus, in this work, GO sheets were used to improve the microstructure and mechanical properties of electro-brush plated Fe coatings. The results showed that GO was reduced to the reduced graphene oxide (rGO) undergoing the electrochemical reduction, and the rGO sheets were co-deposited with those metal atoms during EBP. As expected, the defects number of Fe coatings was decreased obviously with the addition of GO, which is attributed to that the co-deposition process of GO with Fe atoms could facilitate the emission of hydrogen atoms away from the cathode, avoiding the formation of hydrogen-induced defects in coatings. In addition, the grains of Fe-GO composite coatings were remarkably refined as the rGO sheets provided heterogeneous nucleation sites for the primary Fe crystals. Improved micro-hardness and wear resistance were achieved after adding GO. Compared with Fe coatings, the average friction coefficient and weight loss of Fe-GO composite coatings were decreased by 49.5% and 39.7%, respectively, due to the effect of self-lubrication and reinforcement of rGO sheets. (C) 2019 Elsevier B.V. All rights reserved.