Characterization of hydrogen-free diamond-like carbon films deposited by pulsed plasma technology

Diamond-like carbon (DLC) films demonstrated significant advantages in cutt ing and forming non-ferrous materials. The ultra-low friction coefficient a nd high surface hardness make DLC one of the most promising surface modific ation technologies available for processing advanced structural materials. In this study, Ti-doped and hydrogen-free DLC films (a-C:Ti) were synthesiz ed by unbalanced magnetron sputtering of Ti and graphite targets. The high residual stress of the DLC thin films was dissipated through a compound int erface ;consisting of a series of Ti, TiN, and TiCxNy graded interlayers. T he target poisoning problem was resolved with a 2 kHz medium-frequency DC p ower supply. In addition, a 20-100 kHz variable frequency DC power supply w as used for both are suppressing and substrate biasing. The effects of depo sition parameters on film qualities were investigated by SEM/EDS, XRD, EELS and wear tests. Results demonstrated an improved DLC thin film with superi or microhardness and adhesion strength compared with the conventional DLC d eposited by PVD or PECVD processes. (C) 1999 Elsevier Science S.A. All righ ts reserved.