Effect of bath stabiliser on performance of electrodeposited Ni–W coatings

Abstract

The paper describes the influence of the addition of a stabiliser agent on the composition of the bath and the performance of the electrodeposited nickel–tungsten (Ni–W) coatings under working conditions. The effects of the working temperature (65°C) and the addition of a stabiliser on the complexes of Ni and W present in a Ni–W electrolyte were analysed. It has been qualitatively demonstrated that an increase in temperature slightly modifies the speciation curves of Ni and W complexes, and the introduction of a stabiliser does not modify the formation of the metal complex, allowing the electrolyte to be stable during long periods of time. The deposit obtained in an aged electrolyte has a high resistance to corrosion and a good resistance to wear and the hardness can be elevated to ∼1200 HV after the application of a heat treatment.

Keywords:

• Electrodeposition
• Ni–W alloy
• Scanning electron microscopy
• Stabiliser
• Hard chromium