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

Abstract

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.