Fabrication and High Temperature Friction Behavior and Oxidation Resistance of Ni-Co-ZrO₂ Composite Coating

Ni-Co alloy and ZrO₂ micron particles were codeposited on 45 carbon steel by electrodeposition. The composition and microstructure of the composite coating were characterized. The high temperature tribological properties were carried out by a pin-on-disk tribo-tester. Additionally, the oxidation resistance was evaluated via high temperature circulating oxidation test. The results indicated that the deposited composite coating showed dispersed ZrO₂ particles and continuous Ni-Co matrix, and there were no obvious pores, cracks and other defects at the interface between the composite coating and the substrate. The embedded ZrO₂ particles changed the friction mechanism from adhesive wear to abrasive wear, the wear loss rate and friction coefficient of Ni-Co-ZrO₂ composite coating were lower in comparison with that of Ni-Co alloy coating and carbon steel substrate. In addition, the embedded ZrO₂ particles exerted a reactive-phase effect on the growth of nickel oxide and cobalt oxide, and effectively reduced the oxidation rate of the substrate at high temperature. Therefore, the Ni-Co-ZrO₂ composite coating presents better oxidation resistance, when compared with Ni-Co coating.

Keywords:
Electrodeposition; Ni-Co-ZrO₂ composite coatings; High temperature tribological behavior; Oxidation resistance