46 / 2021-06-29 14:37:32

Effect of CeO2 on tribological properties of HVOF-sprayed Cr3C2-NiCrCoMo composite coatings at high temperature

Cr3C2-NiCrCoMo/nano-CeO2 coating,high-temperature tribological properties,cerium oxide,secondary precipitation

To improve the high-temperature tribological properties of chromium carbide cermet coating, a novel Cr₃C₂-NiCrCoMo/nano-CeO₂ (NCE) composite coating was prepared by collaborative modification with micro-CoCrMo and nano-CeO₂ powders. The objective of this work is to study the influence of nano-CeO₂ content on the high temperature tribological properties of the coating. First, the NCE composite powder was deposited by the high-velocity oxygen fuel (HVOF) spray. Then the influence of different nano-CeO₂ proportions on the high-temperature friction and wear resistance of coatings at 400 °C, 600 °C and 800 °C was investigated. Moreover, the microstructure and phase composition of the wear scar surface were characterized by SEM and EDS. The results indicate that, compared with the initial Cr₃C₂-NiCrCoMo (NCC) coating, the novel NCE coating exhibits improved wear resistance with lower friction coefficient and wear depth due to the lubrication of oxides contributed by the improvement of oxide film adhesion. The wear mechanism of coating mainly consists of the abrasive wear and surface fatigue wear. The surface fatigue wear resulted from the fatigue fracture and delamination of the oxide film. The addition of CeO₂ decreases the threshold temperature of Oswald ripening triggered by nano-sized Cr₃C₂ particles, which promotes the growth and aggregation of the precipitated Cr₃C₂ from the bonding phase of the coating.