RELATION OF FRICTION AND WEAR TO PROCESSING PARAMETERS OF POLYCRYSTALLINE DIAMOND FILMS GROWN ON SILICON AND SILICA SUBSTRATES BY THE HOT-FILAMENT METHOD

Polycrystalline diamond films were deposited on silicon and silica sub strates in a hot filament chemical vapor deposition reactor using veno us pretreatment times and methane gas concentrations. Friction and wea r tests were performed with a pin-on-disc tribometer under 100 and 200 gf loads without lubrication in the ambient environment. Tests show t hat friction coefficients decrease with both increasing load and numbe r of traces, which was attributed to the formation of graphite during wear. Wear tests indicate graphitization to be the primary wear mechan ism, with occasional wear pits caused by grain pull-out. The formation of wear pits is believed to be related to the presence of amorphous c arbon in a very small fraction of the grain boundaries.