Electrophoretic deposition of graphene oxide on NiTi alloy for corrosion prevention

Graphene oxide (GO) coating was prepared on the surface of a NiTi shape-memory alloy via a simple and practical electrophoretic deposition method from an aqueous suspension containing GO at low temperatures. The coating was characterized by field emission scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy. The adhesion force and stabilization of the GO coating were analyzed by using a coating adhesion scratch testing system. The surface of the GO-coated NiTi exhibited hydrophilicity with a water contact angle of 17.6°. Moreover, the corrosion resistance of NiTi alloy was evaluated by a potentiodynamic polarization test in Hank's solution. The potentiodynamic polarization curves revealed that GO-coated NiTi demonstrated a more positive corrosion potential (Ecorr, −107 mV) than bare NiTi (Ecorr, −186 mV), and the corrosion current density (Icorr) decreased by approximately two orders of magnitude. The improved corrosion resistance and hydrophilicity of NiTi coated with GO compared with those of bare NiTi were mainly attributed to the GO coating.