High temperature friction in the presence of humid air is the process where oxidation plays an important role and is rather impossible to avoid. Oxidation takes place all over the surface of rubbing couple but is particularly activated in the contact area. Energy dissipated in this area makes contact temperature still higher as compared with surroundings and thus promotes several tribo-chemical processes occurring in it. It amounts to preparation of hard, wear resistant coatings which simultaneously will play a role of source of elements for tribo-chemical oxidation reactions, resulting in creation at their surface a desirable, lamellar oxides and oxide-derivative phases, playing a role of high temperature lubricant. As such hard coatings, doped carbides and nitrides of molybdenum and vanadium can be considered. Decrease of friction at elevated temperatures should be a result of softening or even micro-melting of appropriate phases generated within tribo-contact. Of course, in such a situation, we deal with chemical wear of basic, hard coating. Anyway, such a wear seems to be less destructive for tribo-contact than abrasive wear caused by hard particles released from rubbing surfaces. Lubrication effect should appear at relatively high temperatures, exceeding the range of stability and wear resistance of basic hard coating. For elaboration of such multifunction, temperatureadaptive coatings, a basic knowledge of tribological properties of phases created during high temperature friction is necessary.
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