Preparation And Microtribological Characterization Of Hydrogenated Diamond-like Carbon Films

Diamond-like carbon?DLC?films have been widely used in the micro-system due to its high hardness and excellent chemical stability.It will reduce friction and wear of the micro-system devices and prolong its service life.Subject to the limitations of micro-system space dimensions,micro devices always exist in the form of micro/nano size.It will lead to the strong size effect,and nano/micoscale devices will show different material tribological properties comparing with the macroscale.The author successfully prepared the hydrogenated DLC films by plasma enhanced chemical vapor deposition?PECVD?under different parameters.The structure,morphologies and properties of the films were investigated by the Raman spectrum,three-dimensional white profilometer,atomic force microscope?AFM?,scanning electron microscope?SEM?,nano hardness tester and friction wear tester.The macrotribological properties and mechanisms of the film were discussed detailedly in this paper.?1?The hydrogenated DLC films with the thickness of 500?900 nm were deposited on steel and silicon wafers by PECVD under different parameters.The film deposited under radio-frequency power of 200 W showed broad spectra composed of a D band and a G band,which were similar to the peaks observed in conventional DLC films.And the film deposited under CH₄/H₂=10/10 had moderate sp³/sp².The surface morphologies of the films were smooth and the surface roughness of the films were about 2?4 nm.The hardness of the films decreased with the ratio of the H2increasing.The maximum hardness and elastic modulus of the film were 11.5 and 97GPa,and the minimum hardness and elastic modulus were 7.5 and 63 GPa.So the films had good mechanical properties.?2?The macotribological properties of the film were investigated under atmospheric environment.The film deposited under the radio-frequency power of 200W had better macotribological properties than other films.The film deposited under CH4/H2=10/10 with moderate sp³/sp also had the best macrotribological properties,and the friction of the film was about 0.2.?3?In the range of 1×10¹?1×10³?N,the fiction coefficient decreased gradually with the load increasing and the main reason is the surface morphology.In the range of 1×10³?1×10⁴?N,the fiction coefficient first increased and then decreased gradually with the load increasing and the main reason is the adhesion force.In the range of 1×10⁴?7×10⁵?N,the fiction coefficient was stable with the load increasing.In the range of 7×10⁵?1×10⁶?N,the fiction coefficient increased with the load increasing the main reason is the abrasion of the film.The film deposited under CH₄/H₂=10/10 with moderate sp³/sp² had the best microtribological properties.The sliding velocities had little influence on the friction coefficient of the film in the range of 100?900?m/s.