INFLUENCE OF DEFECTS AND MORPHOLOGY OF DIAMOND-LIKE CARBON COATINGS ON THEIR TRIBOLOGICAL BEHAVIOR

The preparation of hard carbon and diamond-like carbon coatings depend s on the ratio of C2H2/H-2 concentrations, as described by many author s [1]. A single crystal with good crystalline quality was prepared at low ratio (below 1% C2H2). The polycrystalline structure growth at hig h concentration (from 2 to 5% C2H2) generates defects. We have deposit ed by the CVD method different films at different gas ratios to invest igate their tribological behaviour. A variety of techniques were used to characterize the coatings. The surface morphology and grain size we re determined by scanning electron microscopy. The structure and amoun t of diamond in the films were analysed by high-resolution transmissio n electron microscopy and ionization electron energy loss spectroscopy . Twinning and stacking faults were the predominant defects observed i n all of the polycrystalline samples. The investigation of the tribolo gical behaviour of these films shows that the defects as well as graph itic components are favourable factors in the friction and wear behavi our of coatings. This paper reports the influence of C2H2/H-2 concentr ation on the films morphology and their tribological behaviour.