| AVS 56th International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF-ThP |
| Session: | Aspects of Thin Films Poster Session |
| Presenter: | S. Narita, Kogakuin University, Japan |
| Authors: | S. Narita, Kogakuin University, Japan I. Takano, Kogakuin University, japan |
| Correspondent: | Click to Email |
Diamond-like carbon (DLC) has the amorphous structure that is chiefly composed by graphite (sp2) and disordered graphite (sp3) state. Therefore mechanical property of DLC generally shows high hardness and low friction. DLC film has been prepared by various method of chemical vapor deposition (CVD) or physical vapor deposition (PVD) including the sputtering method. Commercial application of DLC has been already performed as engine parts of an automobile or surface coating of a hard disk.
In this study, DLC films were formed using Ar+ or He+ ion beam assist in a naphthalene (C10H8) atmosphere. C10H8 is aromatic hydrocarbon with two benzene rings of a solidly in normal temperature and pressure. In our previous study, toluene (C7H8) of aromatic hydrocarbon with one benzene ring was used at same experimental process. By using C10H8 as an atmosphere gas, the higher deposition rate is expected than C7H8 gas. The formation conditions of DLC were changed with ion beam accelerating voltage and current density. Current dependence was performed by ion beam current density of 10 to 70 μA/cm2 with a constant accelerating voltage of 5 kV, while voltage dependence was performed by 1 to 12 kV with a constant current of 10 μA/cm2.
The mechanical properties of hardness and friction coefficient were determined using the dynamic micro Knoop hardness tester and the pin-on-disk tribo-tester with a SUJ2 ball of a 1/4 inches diameter, respectively. The conditions of examination were fixed at a load of 0.98 N, a revolution speed of 135 rpm, a sliding diameter of 10 mm and a sliding distance of 10 m. Atomic concentration and structure of the films were investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, respectively.
The suitable property of Knoop hardness and friction coefficient were obtained by conditions of accelerating voltage of 5 kV with current density of 10 μA/cm2. Knoop hardness of the film showed 5.37 GPa using Ar+ ion beam irradiation, while the friction coefficient of the film showed 0.117 using He+ ion beam irradiation. It was clear that property of DLC film was changed by ion species. In the case of He+ ion beam irradiation, low friction property was shown at 5 to 7 kV with 10 μA/cm2, while high hardness property was obtained by Ar+ ion beam irradiation of 5 kV with 10 to 40 μA/cm2.