| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Tuesday Sessions |
| Session TF-TuP |
| Session: | Thin Films Poster Session |
| Presenter: | Tsuyoshi Inoue, Kogakuin University, Japan |
| Authors: | T. Inoue, Kogakuin University, Japan I. Takano, Kogakuin University, Japan |
| Correspondent: | Click to Email |
DLC is amorphous carbon that contains a significant fraction of sp2 and sp3 bonds. It is known that their films show a low friction coefficient and its high hardness is applied in a mechanical field such as cutting tools or frictional parts. DLC films were formed by the ion beam assisted evaporation method in the early 1970's, and after that have been manufactured by various methods. The film formation of DLC is performed in a high temperature basically. On the contrary the film formation in the negative temperature is hardly performed. In our experiment, an N2+ ion beam to the substrate was irradiated with introduction of a hydrocarbon gas in a vacuum chamber. This deposition method has some independent parameters from the film formation condition in comparison with other dry process methods. Therefore this method is anticipated in appearance of superior characteristics such as a high adhesion. In our previous research, iced water was used to urge adsorption of a hydrocarbon gas on the substrate temperature control. It was suggested that adsorption of a hydrocarbon gas depended on the substrate temperature.
In this study, the control of a substrate temperature was performed by using the LN2 and heater controlled by PID. Stainless steels (304SS), Si plates and slide glasses were prepared for sample substrates. The formation conditions of DLC films were changed from -150 degrees to 25 degrees and were an N2 gas pressure of 4x10-3 Pa under an ultimate pressure of 6x10-4 Pa. C7H8 as an ambient gas was introduced by to determine the gas ratio using QMS. The ion beam irradiation was performed with 1 kV in an accelerating voltage and 30 µA/cm2 in a current density, through an exposure time of 3600 s. The film structure was determined by Raman spectroscopy and the thickness was measured using a spectrometer of a fiber injection type. Vickers hardness and the friction coefficient were measured by a micro hardness tester and a tribotester of a ball-on-disk type, respectively. The tribotester was set with an Si3N4 ball as a counter material and the examination was carried out with a constant load of 0.98 N until a sliding distance of 100 m.
ID/IG ratios of DLC thin films measured by Raman spectroscopy showed the higher sp3 contents at -100℃ of a cooling substrate temperature. The suitable mechanical property of the DLC films was obtained by a temperature of -100 degrees and the friction coefficient was 0.20 at a distance of 100 m.