Preparation Of Diamond-Like Carbon Films By RF Magnetron Sputtering

Diamond-like carbon(DLC)film has excellent performance,including high hardness,smooth surface,small friction coefficient,good corrosion resistance and good biocompatibility.It can be extensively applied in the fields of nuclear reactor protection film,submarine corrosion protection layer,aviation device solid lubricant,mobile phone screen protective film,glasses and other areas of the film,therefore,it is one of the most indispensable strategic materials in the 21 st century.However,there are only few studies and practical patents on the field of DLC films in China.In particular,the preparation technology and further industry applications of DLC films are quite limited.Driving from such motivation,the present work focuses on exploring optimum conditions of DLC films by using radio frequency(RF)magnetron sputtering method and its biological applications.DLC films have been fabricated by RF magnetron sputtering on(100)silicon wafers.The method of RF magnetron sputtering for preparing DLC films has the merits of high sedimentation rate,strong binding force between the films and the substrate,low deposition temperature.Raman spectroscopy was used to characterize the as-prepared DLC films by exploring the influence of temperature,RF power,working atmospheric pressure and bias on the film quality.It was found that when the RF power is 120 W,the substrate bias is-100 V,the substrate temperature is room temperature,the working gas is argon,and the working atmospheric pressure is 1.0Pa,the content of the sp3 hybrid bond in the DLC films is higher.Scanning electron microscope(SEM)was employed to study the influence of various substrate temperature and negative substrate bias on the films surface quality.It has been observed that the surface of the film is smoother when the substrate temperature is room temperature and the substrate bias is-100 V as the other parameters remained constant.Nickel titanium(NiTi)alloy is a shape memory alloy material that is widely usedin medical implantation.However,it is rather rough and easy to rub with the tissues and organs after implantation in the human body,leading to inflammatory reaction of the adjacent tissues on account of the wearing debris particles;moreover,direct usage of NiTi alloy may result in potential carcinogenic risks,because it is easily decomposed of nickel ion or nickel salt in the context of complex physical and chemical environment.Therefore,these drawbacks mentioned above limit the application of the NiTi alloy in clinic.Surface treatment of NiTi alloy is highly require.DLC films can recover the deficiency of NiTi alloy in the clinic by reason that it can validly prevent the precipitation of Ni ion due to its superior performance and smooth surface.The preparation of DLC film has the merits of simple operation,low cost and wide market prospect.In present work,the optima DLC films have been fabricated covering NiTi orthodontic arch wire by RF magnetron sputtering method.The growth parameters are RF power 120 W,working atmospheric pressure 1.0Pa,room temperature,bias voltage-100 V,argon gas flow 20 sccm,thickness of films about 1?m.The NiTi orthodontic arch wire and DLC-NiTi were characterized by Raman spectrometer,SEM and electrochemical station.After electrochemical etching,DLC-NiTi and NiTi wire were measured by SEM.As a result,DLC-NiTi was much smoother than uncoated NiTi wire,and there were no observable scratches and black spots.After electrochemical corrosion,the surface of DLC-NiTi is not corrosive and has a metallic luster on the surface,indicating that the DLC-NiTi is more resistant to corrosion than NiTi arch wires.