Effect of H-MWCNTs addition on anti-corrosion performance and mechanical character of Ni-Cu/H-MWCNTs composite coatings prepared by pulse electrodeposition technique

Ni-Cu/H-MWCNTs composite coatings with outstanding corrosion resistance and high wear resistance were prepared by the pulse electrodeposition technology. The micro-surface morphology and corrosion behavior of the coatings were represented by high-resolution field emission scanning electron microscopy , potential polarization curve, electrochemical impedance spectroscopy and scanning electrochemical microscope. The chemical composition and crystal structure of the coatings were characterized by energy dispersive spectrum, X-ray photoelectron spectroscopy and X-ray diffraction. The mechanical properties are studied by digital microhardness tester and multifunctional material surface testing machine. We found that the successful doping of H-MWCNTs changed the micro-structure and morphology of the Ni-Cu-based coating, making the coating smoother and denser. Furthermore, the average crystallite size of the Ni-Cu/H-MWCNTs (0.5 g/l) composite coating is 13.28 nm. The microhardness and average friction coefficient of the composite coating (0.5 g/l) are 587.04 Hv and 0.178, respectively. It was also found that the composite coating (0.5 g/l) has the best anti-corrosion performance, which is 3.2 times that of the pristine Ni-Cu-based coating. Through SECM diagrams, the composite coating (0.5 g/l) has excellent pitting resistance in 3.5  wt % NaCl solution.