INFLUENCE OF THE PACVD PROCESS PARAMETERS ON THE PROPERTIES OF TITANIUM CARBIDE THIN-FILMS

Wear-resistant titanium carbide (TiC) coatings were deposited by plasm a-assisted chemical vapour deposition on high-speed steel. The influen ce of the partial pressure ratio of methane and titanium tetrachloride (p(CH4)/p(TiCl4)), the plasma voltage and the pulse/pause ratio on th e composition and properties of the TIC coatings have been investigate d. Small partial pressure ratios p(CH4)/p(TiCl4) up to about 15 result in nearly stoichiometric TiC coatings at high plasma voltage. Higher partial pressure ratios cause excess carbon, which is bound as C-C or C-H. An increasing carbon content was found also for both increasing p lasma voltage and increasing pulse/pause ratio. The layer hardness was found to decrease with increasing excess carbon. No significant influ ence of composition on the friction coefficient has been detected. (C) 1998 Elsevier Science S.A.