Mapping the structure and chemical composition of MAX phase ceramics for their high-temperature tribological behaviors

MAX phase ceramics is a large family of nanolaminate carbides and nitrides, which integrates the advantages of both metals and ceramics, in general, the distinct chemical inertness of ceramics and excellent physical properties like metals. Meanwhile, the rich chemical and structural diversity of the MAXs endows them with broad space for property regulation. Especially, a much higher self-lubricity, as well as wear resistance, than that of traditional alloys and ceramics, has been observed in MAXs at elevated temperatures in recent decades, which manifests a great application potential and sparks tremendous research interest. Aiming at establishing a correlation among structure, chemical composition, working conditions, and the tribological behaviors of MAXs, this work overviews the recent progress in their high-temperature (HT) tribological properties, accompanied by advances in synthesis and structure analysis. HT tribological-specific behaviors, including the stress responses and damage mechanism, oxidation mechanism, and wear mechanism, are discussed. Whereafter, the tribological behaviors along with factors related to the tribological working conditions are discussed. Accordingly, outlooks of MAX phase ceramics for future HT solid lubricants are given based on the optimization of present mechanical properties and processing technologies.