The study of electroless Ni–P alloys with different complexing agents on Ck45 steel substrate

Abstract

Ck45 Steel was electroless coated with nickel–phosphorus alloy from a bath containing sodium hypophosphite and different complexing agents (sodium citrate, sodium acetate and lactic acid). The effect of different complexing agents on phosphorus content, morphology, structure and hardness of the deposits was studied. The coating compositions deposited were determined by using energy dispersive X-ray spectroscopy (EDX). Scanning electron microscopy (SEM) was used to study the morphology of coatings. The anti-corrosion properties of Ni–P coatings were investigated in 3.5% NaCl solution by the weight loss and potentiodynamic polarization techniques. It has been found that Ni–P coating obtained using sodium citrate complexing agent with the spherical nodular structure and smooth surface showed higher microhardness and anti-corrosion resistance.

Keywords

• Electroless Ni (EN)
• Complexing agent
• Sodium hypophosphite
• Corrosion
• Hardness