Effect of Heat Treatment Temperature on the Corrosion Performance of Electroless Ni–P/Ni–P–TiO₂ Deposits on Carbon Steel

The Anatase type TiO₂ particles of 200–300 nm were co-deposited in the electroless Ni–P composite layer on carbon steel using electroless nickel bath. The changes in micro structure, crystal size and micro strain of the deposits with heat treatment temperature were examined using X-ray Diffractogram and Scanning Electron Micrographs and the corrosion behaviour of the coatings were evaluated using tafel polarization studies in 3.5 wt% Sodium Chloride solution. The result showed that the corrosion resistance of the coatings decreased by increasing heat treatment temperature. Further, the corrosion mechanism of the coatings was discussed in terms of phase transformation, porosity, crystal size and micro strain.