The nanostructure Ni-Co-W and Ni-Co alloy coatings were electrodeposited on a copper substrate using different applied current densities, in a modified Watts-type bath. The current densities used were 2.5, 5, 7.5, 15, 50 and 70 mAcm -2 and the substrate. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were employed to study the effect of electrodeposition current density on morphology and grain size of deposits. The results showed that morphology of deposits were changed from pyramidal to mixed morphology (pyramidal and blocky) by increasing the current density. A homogeneous nodular surface morphology was obtained at all current densities on Ni-Co-W coating. The coatings were single-phase solid solutions with average grain sizes about 6-11 nm, calculated from x-ray diffraction patterns using the Scherrer equation. Grain size was less than the Ni-Co coating in similar density currents. Electrochemical impedance spectroscopy (EIS) showed that increasing levels of penetration by surface absorption of ions in the Ni-Co-W coatings. Electrochemical impedance spectroscopy (EIS) for Ni-Co coating showed the effect of hydrogen absorption and formation of intermediate compounds was Nanocrystalline structure. Tafel test results done in the solution %3.5 sodium chloride solution showed that nanocrystalline coatings have good corrosion resistance. Microhardness test results showed improvement of this parameter in the Ni-Co-W Coating than Ni–Co caoting. This improvement is due to the presence of tungsten. Microhardness Ni-W coating is higher than other coatings and is caused by cobalt in this coating. The W and Co contents of the coatings decreased with an increase in the applied current density.
