WEAR-RESISTANT COMPOSITE COATINGS DEPOSITED BY ELECTRON ENHANCED CLOSED FIELD UNBALANCED MAGNETRON SPUTTERING

There is presently considerable interest in wear resistant coatings pr oduced using closed field unbalanced magnetron sputtering technology. For example, layered films of diamond-like carbon (DLC) with tungsten or titanium additions have been widely reported. The benefit is that t he mechanical properties are enhanced (e.g, giving greater toughness); also it is possible to control the stress state and enhance adhesion. Here we report the further development of this concept by the additio n of TiN, TiCN and TiC layers in DLC-based composites, utilizing an ad ditional source of electrons in the vicinity of substrate to enhance i onisation of the plasma and increase coating density. Composite coatin gs of ceramics TIN, TiCxNy, TiC, CrN, TiCrN, TiCrCN, TiCrC, metal dope d Ti-x%-DLC and their combinations were deposited on 316 stainless ste el substrates. The mass flow of reactive gases into the chamber was co ntrolled using plasma optical emission monitoring to achieve the desir ed coating composition. The morphology of the coatings was investigate d and correlated with Knoop microhardness, scratch adhesion, pin-on-di sc and wet abrasive wheel tests. Dense T-type structures were found fo r most of the coatings and a high toughness of Ti-30%-DLC coating with a TiC interlayer was observed. Low friction coefficients of 0.15-0.18 for coatings with Ti-x%-DLC layers confirmed their benefit in sliding wear applications, while TiCN coatings were found to be the best in a brasive wear conditions.