MATERIAL PROPERTIES AND TRIBOLOGICAL PERFORMANCE OF RF-PECVD DEPOSITED DLC COATINGS

Diamond-like carbon (DLC) coatings were deposited on to silicon, glass and metal substrates, using an rf-plasma enhanced chemical vapour dep osition (rf-PECVD) process. The resultant film properties were evaluat ed in respect of material and interfacial property control, based on b ias voltage variation and the introduction of inert (He and Ar) and re active (N-2) diluting gases in a CH4 plasma. The analysis techniques u sed to assess the material properties of the films included AFM, EELS, RBS/ERDA, spectroscopic, electrical, stress, microhardness, and adhes ion. These were correlated to the tribological performance of the coat ings using wear measurements. The most important observation is that H e dilution (> 90%) promotes enhanced adhesion with respect to all subs trate materials studied. Coatings typically exhibit a microhardness of the order of 10-20 GPa in films 0.1 < d < 2 mu m thick, with associat ed electrical resistivity in the range 10(8) < rho < 10(12) Omega.cm, coefficient of friction < 0.1 and surface RMS roughness as low as 2 An gstrom. The results are discussed with respect to surface pre-treatmen t, ion surface bombardment, interfacial reactivity and changes in plas ma gas breakdown processes. (C) 1998 Elsevier Science S.A.