Effect of Phosphorus on the Corrosion Resistance of Nickel Electrocoatings

Abstract

The electrodeposited Ni-P coatings are commonly used for their electrocatalytic properties towards hydrogen evolution reaction. However, their corrosion resistance in concentrated alkaline solutions is still less known. In this work, the effect of phosphorus on the resistance of nickel electrodeposits to electrochemical corrosion in 5 M KOH solution, was studied. Open circuit potential and anodic polarization measurements were performed to determine parameters of the corrosion resistance of the crystalline Ni deposit and amorphous Ni-P electrocoating. It was found that alloying of nickel with phosphorus is the effective manner of the improvement of the corrosion resistance of the nickel coatings. The obtained Ni-P electrode material contained 10 wt.% of P and revealed amorphous structure. The increase in the corrosion resistance of the Ni90P10system as compared to that determined for comparable Ni polycrystalline electrode was due to phosphate formation responsible for broad passivation potential in alkaline medium and amorphous structure.