Paper TF-ThP14
Interface Control Effect of Nitrogen-doped Diamond-like Carbon by Ion Beam Assisted Deposition Method

Thursday, October 23, 2008, 6:00 pm, Room Hall D

DLC (Diamond-like Carbon) constituting a class of new materials is an amorphous carbon including hydrogen and has similar properties of matter with a diamond. DLC film was formed by the ion beam evaporation method in the early 1970's,¹ and after that has been manufactured by various methods such as CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). Because the representative mechanical property of DLC is to show the high hardness and low friction coefficient, DLC is applied in various filed such as motor parts or tools. Also the electric properties of DLC are anticipated as a field emission source. In this study, mechanical properties were investigated about the interface between the DLC film and the substrate controlled by the ion beam assist. The ion beam assisted deposition method has many parameters on the film formation condition in comparison with other dry process methods. Therefore this method was anticipated in production of new characteristics such as a high adhesion film. The interface control was performed by changing two procedure. The first process was performed by an accelerating voltage of 12 kV with a current density of 40 μA/cm² to obtain the high hardness property. The second process was performed by an accelerating voltage of 5 kV with a current density 40 µm/cm² to obtain the low friction property. An N₂⁺ ion beam and a C₇H₈ gas atmosphere were used on this ion beam assisted deposition method. Composition and microstructure of these films were investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The hardness was measured from an indentation method with a Knoop indenter. The friction coefficient was measured for an SUJ2 ball with a constant load 0.98 N until the sliding distance reached a length of 10m. As for the sample formed the mixing layer at the first process, mechanical properties were improved in the hardness and the friction coefficient. The Knoop hardness of the film showed 23 GPa. The sample formed using both of first process and second process showed 0.194 in the friction coefficient, because mechanical properties were improved by the interface condition. The depth profile of the mixing layer showed gradual change of C and Fe (as substrate material) in comparison with a sumple without mixing layer.

¹S. Aisenberg , R. Chabot : J. Appl. Phys., 42, 2953 (1971).