Electroless Ni–W–P Coating and Its Nano-WS2 Composite: Preparation and Properties

The ternary alloy Ni–W–P and its WS 2 nanocomposite coatings were successfully obtained on low-carbon steel using the electroless plating technique. The sodium tungstate (Na 2 WO 4 ) concentration in the bath was varied to obtain Ni–W–P deposits containing various Ni and P contents. WS 2 composite was obtained with a suitable concentration of Na 2 WO 4 in Ni–P coating. These deposits were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX) studies. The corrosion behavior was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies in 3.5 wt % NaCl solutions, and the corrosion rates of the coatings for Ni–P, Ni–W–P, and Ni–W–P–WS 2 were found to be 2.571 × 10 –5, 8.219 × 10 –7, and 7.986 × 10 –7 g/h, respectively. An increase in the codeposition of alloying metal tungsten (W) enhanced the corrosion resistance and microhardness and changed the structure and morphology of the deposits. Incorporation of WS 2 nanoparticles to Ni–W–P alloy coating reduced the coefficient of friction from 0.16 to 0.11 and also helped in improving the corrosion resistance of the coating further.