The influence of nano-CeO2 on tribological properties and microstructure evolution of Cr3C2-NiCrCoMo composite coatings at high temperature

Abstract

With the aim of further improving the high-temperature tribological properties and extending the application of typical chromium carbide cermet coating, a novel Cr3C2-NiCrCoMo/nano-CeO2 (NCE) composite coating deposited by high-velocity oxygen fuel spray (HVOF) was developed based on the collaborative modification of the multielement alloy adhesive phase. The influence of nano-CeO2 content on high-temperature tribological properties and microstructure evolution of the coating during high-temperature friction was studied. Tribological properties, microstructure and phase composition of the coating after friction at 400 °C, 600 °C and 800 °C were carefully investigated. The results indicate that the novel NCE coating exhibits improved wear resistance at high temperature with lower friction coefficient and wear depth due to the lubrication of oxides and improvement of oxide film adhesion. The wear mechanism of the NCE coating mainly consists of abrasive wear and surface fatigue wear. With the increase of friction temperature, the oxide film replaces the coating surface as the main object of wear. The addition of nano-CeO2 decreases the threshold temperature of Ostwald ripening triggered by the secondary precipitated nano-Cr3C2 phase and promotes the growth and aggregation of the nano-Cr3C2 precipitated from the adhesive phase of the NCE coating, which contributes to wear resistance of the coating in the subsequent friction.