Simultaneously improved corrosion/wear resistances of Mg alloy through an ultra-thin Mg(OH)2/graphene-APTES coating

In order to expand the applied range of Mg alloy, a variety of coatings have been designed to improve their corrosion and wear resistance. Here, we report a 3-aminopropyl triethoxysilane (APTES) modified Mg(OH)2/reduced graphene oxide (RGO) hybrid coating with integrated anti-corrosion/wear property on Mg alloy, which is prepared by in-situ crystallization using a facile hydrothermal method. The ultra-thin Mg(OH)2/RGO layer with 250 nm exhibits a dual-structure, in which the inner layer is composed of Mg(OH)2, and then RGO sheets hybrid with Mg(OH)2 via the hydrogen bond to form the outer layer. The lubrication of RGO sheets and the high hardness of dense Mg(OH)2 give rise to the significant decrease of wear rate, which is two orders of magnitude less than that in Mg substrate. Next, the APTES layer effectively fills the pores and defects on the surface of Mg(OH)2/RGO via the Si-O-Mg and amide bond, and it forms a barrier film enriched with Si-O-Si bond via the self-crosslinking reaction. The effective combination of inorganic and organic layer contributes to the improved anti-corrosion property.