Abstract: High temperature represents one of the most extreme and demanding environments for mechanical systems in service. High-performance lubricating and wear-resistant coating with a wide temperature range capabilities serve as an effective solution to address high-temperature friction and wear in mechanical systems, enabling reliable long-term service.A NiCoCrAlY-Cr₂O₃-Ag-Mo-Ta composite coating designed for wide-temperature-range lubricating and wear-resistance was fabricated using advanced atmospheric plasma spraying technology. The coating primarily consists of (Ni, Cr), Cr₂O₃, Ag, and a small amount of Al₈(CoCr)_3.6Y, indicating that during the thermal spraying process, the raw materials do not undergo significant oxidation or decomposition, and the lubricating phases do not participate in chemical reactions. The hardness of the coating is 405.70 HV_0.2. Tribological studies reveal that the coating exhibits poor lubrication performance from room temperature to 200 ℃. In contrast, optimal lubrication and wear resistance are achieved at 400 ℃ and 600 ℃, with the friction coefficient and wear rate of 0.44 and 5.23×10^－5 mm³/(N·m) at 400 ℃, and 0.48 and 4.88×10^－5 mm³/(N·m) at 600 ℃. At the high temperature of 800 ℃, the coating maintains comparatively good lubricity but suffers severe wear, primarily because excessive oxidation of the coating produces a loose surface oxides that hinder the formation of a dense glazed oxide layer.

Key words: coating, solid lubricating, high temperature tribology, lubrication and wear mechanism