ULTRASOUND EFFECTS ON THE TRIBOLOGICAL PROPERTIES OF SYNTHESIZED DIAMOND FILMS

The friction and wear behavior of chemical vapor deposition grown diam ond films has been investigated under strong ultrasound conditions at the friction interface. Experiments were performed on an alternating ' 'pin-on-plate'' tribometer constructed as an ultrasonic motor with exc ited bimodal mechanical vibrations at the frequency of 20 kHz. Ultraso und sliding of the films was done against alumina ceramics and with th e diamond film itself. We have shown that chemical vapor deposition di amond films can be fast polished mechanically without significant grap hitization by ultrasonic treatment. The initial film roughness was red uced from an average R(a) approximate to 3000 nm to R(a) approximate t o 10 nm. The polishing decreased the static coefficient of friction of the diamond film from about 0.53 to about 0.12. The operative mechani sm for the polishing in the case of initially rough diamond samples ap pears to be asperity fracture. For smooth diamond samples it is sugges ted that tribochemical oxidation is also a polishing mechanism. (C) 19 95 American Vacuum Society.