Effect of Load, Friction Pair and Medium Environment on the Tribological Behavior of Multilayer Ti-doped Graphite-like Carbon Films

In order to solve the problem of high internal stress and low adhesion strength of amorphous carbon films, multilayer doped graphite-like carbon (GLC) films are prepared on 316L stainless steel substrate by closed field unbalanced magnetron sputtering system. The effect of load, friction pair and medium environment on the tribological behavior of GLC film are investigated by ball-on-disc rotary friction tester. The results show that the multilayer GLC film has compact and uniform structure without obvious defects between the film and substrate, and shows excellent mechanical properties. The friction factor curves of the film under dry friction condition show obvious three-stage characteristics, corresponding to slight abrasive wear, film peeling and the formation of carbon transfer film on the mating balls. The average friction factor of the film increases significantly with the increase of normal load, while the wear rate decreases first and then increases. Compared with ZrO2 ceramic ball, Si3N4 / GLC friction pair has higher friction factor and wear rate due to its higher adhesion tendency and larger Hertz contact radius. Due to its low hardness, GCr15 metal ball causes the carbon transfer film to fall off with the stripping of metal grinding, resulting in relatively high friction factor and wear rate. Compared with the ambient air environment, GLC film is washed by aqueous solution and eroded by corrosive medium Cl- in NaCl solution, resulting in rapid stripping of the film from the substrate, resulting in higher friction factor and wear rate. The results provide a theoretical guidance for improving the service life and working efficiency of amorphous carbon films in different environments.