Microstructural, surface and electrochemical properties of electrodeposited Ni-WC nanocomposites coatings

Abstract

In this work, we study the influences of nano-sized WC particles (diameter size of ∼50 nm), concentrations on the structure, surface morphology, mechanical and electrochemical properties of Ni-WC composite coatings electrodeposited on pretreated copper substrates. The corrosion behavior of Ni-WC composite coatings was studied by the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods in two corrosion media (0.1 M HCl) and (3.5% NaCl). EDS analysis affirms that WC is the incorporated particles and nickel is the blinder metal. The incorporation of WC particles in the nickel matrix forms heterogeneous deposits that contain deep and narrow pores. XRD pattern indicates good crystal structure with (110), (111), (200) and (311) preferred growth orientations. The reinforcement of Ni matrix by nan-sized WC particles refines the grains size of the coatings. Microhardness and roughness of the deposits increase with the increase of WC concentration in the electrolyte bath. Based on the lowest corrosion density and the highest charge transfer resistance value, corrosion tests show that the samples 4 g/L and 1 g/L immersed in the corrosive media of 3.5% NaCl and 0.1 M HCl are the optimum conditions, respectively.

Improving reliability and service life of industrial products via composite electrochemical coatings

“…The wear resistance of WC depends on hardness, part size and impact toughness of the substance particles. The impact toughness does not directly depend on residual micropores due to large WC grains [3]. It was proved that this indicator depends not only on the size, but also on the location of the defect [4].…”

“…These coatings have high adhesive strength and hardness, wear resistance and reliable corrosion protection of steel products [1]. However, high aggressiveness against most structural materials, environmental hazard, and toxicity of hexavalent chromium compounds to living organisms have initiated research on alternatives to using chromium coatings [2,3].…”