Graphene-Reinforced Zn–Ni Alloy Composite Coating on Iron Substrates by Pulsed Reverse Electrodeposition and Its High Corrosion Resistance

In this paper, a novel kind of graphene (Gr)-reinforced Zn–Ni alloy composite coating is successfully prepared on an iron substrate by pulsed reverse electrodeposition. Hydrophilic graphene oxide (GO) is directly added to the electrolyte and reduced to Gr during coating. The experimental results reveal that (1) there is an optimal adding amount (about 0.4 g/L) of GO in the electrolyte for achieving the highest mechanical properties and corrosion resistance; (2) the composite coating shows grain refinement and a dense microstructure due to heterogeneous nucleation sites provided from the Gr sheets during electrodeposition; and (3) compared to the regular Zn–Ni coating, the composite coating exhibits many enhancements, including hardness increase by 2.3 times, elastic modulus increase by 39%, and corrosion rate decrease from 37.66 to 1.30 mils/annum. This process has advantages such as being simple, effective, well repeatable, economical, and supporting large-scale production and is expected to be widely applied in electronics, automobiles, marine engineering, and military industries.