Preparation of Diamond-like Carbon Films by Plasma Source Ion Implantation with External Glow Discharge

抄録

High hardness diamond-like carbon (DLC) films with good adhesion can be prepared by plasma source ion implantation in combination with radio frequency glow discharge plasma. Acetylene gas was used as the source gas to deposit the DLC films. Either pulses of -18 kV with a repetition rate of 1 kHz or DC voltages from -0.5 to -3 kV were applied to the substrate holder. A radio frequency (RF) of 13.56 MHz was applied to a counter electrode to generate a glow discharge plasma.
The films were deposited on austenitic type stainless steel SUS304 as well as silicon wafers and characterized regarding thickness and surface morphology by cross-sectional SEM and by AFM, respectively. The chemical structure was investigated by Raman spectroscopy. The hardness of the films was evaluated by an indentation method. Furthermore, a ball-on-disc test was employed to obtain information about the frictional properties and sliding wear resistance of the films.
The deposition rates of the films were enhanced by the RF discharge. The I_D/I_G value varied, depending on the deposition condition, in the range of 0.49 to 2.0. The hardness of the DLC films was around 19 GPa for the film deposited without RF and up to 26 GPa for the films deposited with RF discharge. A low friction coefficient was derived for all films prepared in this study, with lowest values of 0.04.