Pulse Electrodeposited Super-Hydrophobic Ni-Co/WS2 Nanocomposite Coatings with Enhanced Corrosion-Resistance

Abstract

The hydrophobicity and corrosion resistance of composite coatings can be effectively improved by changing the electrodeposition method and adding inorganic nanoparticles. In this work, the incorporation of WS2 nanoparticles significantly increased the surface roughness of Ni-Co coatings. The best hydrophobicity and corrosion resistance of the Ni-Co/WS2 nanocomposite coatings (water contact angle of 144.7°) were obtained in the direct current electrodeposition mode when the current density was 3 A/dm2 and the electrodeposition time was 50 min. Compared with direct current electrodeposition, the pulsed current electrodeposition method was more conducive to improving the electrodeposition performance of the nanocomposite coatings. Under the conditions of a current density of 3 A/dm2, pulse duty cycle of 70%, and pulse frequency of 1000 Hz, the nanocomposite coatings reached a superhydrophobic state (water contact angle of 153.8°). The nanocomposite coatings had a slower corrosion rate and larger impedance modulus in this state, and thus the corrosion resistance was superior. The wetting state of the Ni-Co/WS2 nanocomposite coating surface was closer to the Cassie–Baxter model. The protective air layer formed by the layered rough microstructures significantly reduced the actual contact area between the liquid and the substrate, achieving excellent hydrophobic and corrosion resistance properties.