Anti-friction mechanism of VAlTiCrMo high-entropy alloy coatings through tribo-oxidation inducing layered oxidic surface. (July 2022)

• Record Type: Journal Article
• Authors: Fan, Jun; Liu, Xuesong; Pu, Jibin; Shi, Yanbin
• Is Part Of: Tribology international. Volume 171(2022)
• Publication Date: 2022-07
• Subjects: Coating -- High temperature friction -- Antifriction -- Oxide -- Wear resistance; Tribology -- Periodicals; 621.89
• DOI: 10.1016/j.triboint.2022.107523
• Languages: English
• ISSNs: 0301-679X

Abstract

Abstract: VAlTiCrMo-based high-entropy alloy coatings with BCC structure were successfully prepared by magnetron sputtering, and the tribological properties were improved by changing Mo content. It is revealed that friction force changed the composition of lubricating phase in the oxide scale of VAlTiCrMo1.6 coating, that is, a complex oxide Al2 (MoO4 )3 as dominant lubricating phase was formed on the surface of oxide scale through tribochemical reaction between simple oxides. And the phase separation in the layered oxide scale caused by thermal diffusion, which is favorable to form continuous lubricating film during friction, was the prerequisite for VAlTiCrMo1.6 coating to acquire low friction and wear. In this process, the addition of Mo played a key role in uphill diffusion and segregation of elements. Graphical Abstract: Diagram of friction process of VAlTiCrMo1.6 coating at 700 ℃ and the oxide layer formed (a) before 600 s and (b) after 1000 s test ga1 Highlights: VAlTiCrMo1.6 coating has the lowest coefficient of friction and wear rate. Al2 (MoO4 )3 is conducive for a lower coefficient of friction. Mo promotes the uphill diffusion and segregation under thermal driving.