| AVS 62nd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science 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 are applied in a mechanical field such as cutting tools or frictional parts. DLC films were formed by the ion beam evaporation method in the early 1970's, and after that have been manufactured by various methods. In our experiment N2+ ion beam was used with metal evaporation to deposit metal doped DLC films. 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, DLC thin films have been prepared by the N2+ ion beam assistance in a hydrocarbon gas. Their results showed that the films contained nitrogen of 8 % and mechanical properties were improved in hardness, friction and abrasion. On the other hand the electrical conductivity of metal doped DLC films prepared by this method is not clear.
In this study, the control of the electrical conductivity of DLC thin films was performed by the metal dope. Stainless steels (304SS) and slide glasses were used for sample substrates. The formation conditions of metal doped DLC films were changed with a metal evaporation rate from 0.01 nm/s to 0.05 nm/s and were an ultimate pressure of 6x10-4 Pa, an N2 gas pressure of 4x10-3 Pa, a C7H8+N2 gas pressure of 2x10-2 Pa in an ambient atmosphere. The ion beam irradiation was performed with 12 kV in an accelerating voltage and 5 µA/cm2 in a current density, through an exposure time of 3600 s. The electrical conductivity and friction coefficient were determined by the four probe method and the tribotester of a ball-on-disk type, respectively. The tribotester was set with the conditions of an SUJ2 ball as a counter material and a constant load of 0.19 N until a sliding distance of 100 m.
The suitable electrical conductivity and mechanical property of the Ti or Cu doped DLC films were obtained by a Ti evaporation rate of 0.03 nm/s and a Cu evaporation rate of 0.05 nm/s respectively. The friction coefficient of Ti or Cu metal doped DLC films was about 0.24 - 0.23 at a distance of 100m. The electrical conductivity was 1.4×105 S/m in Ti doping and 5.17×106 S/m in Cu doping in comparison with the typical DLC film showing 1.0×10-7 S/m.