Ni–W coatings electrodeposited on carbon steel: Chemical composition, mechanical properties and corrosion resistance

Hard, ductile and adherent nanostructured Ni–W coatings were electrodeposited on carbon steel from electrolyte solutions containing sodium tungstate, nickel sulfate and sodium citrate, using different current pulse programs. Current pulse frequency was the dominant factor to define chemical composition, grain size, thickness and hardness. According to the electrodeposition conditions the deposited coatings showed 15–30 at% W, the grain size ranged from 65 to 140 nm, and the hardness varied from 650 to 850 Hv. Tungsten carbide also present in the coating contributed to its hardness. The corrosion resistance of the Ni–W coated steel was tested by potentiodynamic polarization in a neutral medium containing sulphate ions. The Ni–W coating protected the carbon steel from localized corrosion induced by sulphate anions.

► Hard, ductile and adherent nanostructured Ni–W coatings on carbon steel.
► New procedures for achieving deposits by current pulse techniques.
► Current pulse frequency was the dominant factor to define coating characteristics.
► Ni–W coatings protect the carbon steel from corrosion induced by sulphate anions.