Progress of Tribology of Inorganic Protective Films on Friction Surface

A review was given on the current state and progress of the tribological study on the inorganic surface-modifying layers formed by chemical heat treatment and on the surface-protective films formed on the frictional surface by way of the tribochemical reactions among the lubricating oils, the additives, and the metallic surfaces. The state-of-the-art and the prospects concerning the tribological surface modification and the interaction among the modified surfaces and the lubricating oils and additives were summarized. The topics for further investigations were suggested. It was supposed that the study of the interactions among the lubricating additives and the chemically heat-treated surfaces was to promote the study of the preparation science and technology of composites with reduced friction and extended service life. The lubricating oils and additives functioned to reduce the friction and wear by the generation of inorganic surface protective films on the sliding surface through tribochemical reaction thereon, while the wear resistance and load-carrying capacity of a material was considerably increased by introducing an inorganic surface-modification layer on the surface by way of chemical heat-treatment. It was anticipated that the surface-modification techniques based on inorganic surface protective film in connection with the tribochemical reaction films of the lubricating additives would find wider applications in severe environments.