Influence of Residual Stresses on Corrosion and Wear Behavior of Electrodeposited Nanocrystalline Cobalt-Phosphorus Coatings

Abstract

Electrodeposited nanocrystalline Cobalt-Phosphorus (Co-P) alloy coatings deposited onto carbon steel substrates at different phosphorous contents (0.0 wt%, 3 wt% and 10 wt%) were investigated for the influence of residual stress on their corrosion and wear behaviors. X-ray diffraction technique was employed to determine the average crystallite size and residual stresses. The electrochemical corrosion behavior of Co-P coatings compared with a pure nanocrystalline cobalt coating was investigated using open circuit potential and potentiodynamic polarization scans. Wear resistance of electrodeposited nanocrystalline Co-P coatings was tested using pin-on-disc tribometer. The experimental results showed that with increasing phosphorous content, the average crystallite size decreased and coating compressive residual stresses increased. Also, the experimental results revealed that wear and corrosion resistance of Co-P coatings initially increased with increasing compressive residual stress of coating reaching a maximum at residual stresses of 450 MPa and 500 MPa before dropping with further increase in the compressive residual stress.