Wear and corrosion resistant properties of electrodeposited Ni composite coating containing Al₂O₃–TiO₂ composite powder

Abstract

Electrodeposited Ni composite coatings containing ceramic particles have been widely investigated due to their improved mechanical, wear and corrosion resistant properties over plain nickel coatings. The application of one of the most widely studied plasma spray powder, Al₂O₃–13 wt-%TiO₂, has not been explored in electrodeposited nickel composites. In the present study, Ni/Al₂O₃–13 wt-%TiO₂ coatings have been electrodeposited using physically mixed commercial Al₂O₃ and TiO₂ powders. The microhardness, wear and corrosion resistant properties of the coatings have been investigated. It was found that the area fraction of particles incorporated in the nickel matrix was very high at lower current density, and the corresponding composite coating exhibited a maximum microhardness (∼580 HK). Interestingly, corrosion resistance of Ni/Al₂O₃–13 wt-%TiO₂ composite coating was similar to that reported for Ni/TiO₂. The wear behaviour of Ni/Al₂O₃–13 wt-%TiO₂ coating was in between Ni/Al₂O₃ and Ni/TiO₂ coatings and thus exhibited a synergistic effect of the properties of Al₂O₃ and TiO₂ powders.

Keywords:

• Metal matrix composites
• Wear
• Corrosion
• Microstructure
• Electrochemical impedance spectroscopy
• Particle size