Preparation And Properties Of DLC(Ni) Films On 316L SS And Ti Alloy

316L stainless steel(SS)and TC4 titanium alloy(TA)are widely used in the marine field due to their good mechanical properties and low cost.However,in the seawater environment,316 L stainless steel and TC4 titanium alloy are easily subject to friction and intensify corrosion,resulting in a large amount of loss in property.At present,magnetron sputtering is one of the mainstream physical vapor deposition(PVD)surface treatment technologies,and the prepared thin film has the advantages of strong bonding performance and high density.Therefore,DLC thin films were prepared by magnetron sputtering to improve the friction and corrosion resistance of 316 L stainless steel and TC4 titanium alloy in seawater.The DLC film and Ni-DLC film were deposited on 316 L stainless steel and TC4 titanium alloy by RF magnetron sputtering.The Raman,X-ray photoelectron spectroscopy(XPS),scanning electron microscope(SEM),transmission electron microscope(TEM)were used to characterize the composition,morphology and structure of the films.The mechanical properties of the films were characterized by nanoindentation,scratch test and friction and wear test.The corrosion resistance of the thin film in seawater was studied by the Cyclic voltammetry and the eletrochemical impedance method.By adjusting the RF power to optimize the preparation process of DLC films,it can be seen from the cross-sectional morphology that the film structure is compact and homogeneous in thickness.With the increase of RF power,the deposition rate of the film increased.XPS results show that the chemical bonds in the films are mainly C-C bonds,with a small amount of C-O bonds.TEM analysis shows that the DLC film is amorphous structure.As the RF power increases,the hardness,elastic modulus,wear resistance,and film-based bonding strength of the DLC film increase first and then decrease.When the RF power is 200 W,the hardness,elastic modulus,wear resistance,and film-based bonding strength is the best.Although increasing the RF power can increase the density of the film,the wear resistance of the film and the corrison resistance of the film.However,if the RF power is too high,the temperature of the film will increase,which will lead to the graphitization of the film and reduce the mechanical properties of film.The doping of Ni element will change the performance of DLC film and increase the binding force between the substrate and the film.In this paper,the preparation process of Ni-DLC film was optimized by adjusting the nickel target power.Raman spectroscopy shows that the content of sp3 bonds in Ni-DLC films prepared with nickel target power of 10 W is the highest.TEM analysis shows that there are nickel nanocrystals in the Ni-DLC films,the number of nickel nanocrystals increases with the nickel target power increasing from 10 W to 40 W.With the increase of nickel target power,the content of sp3 in the film decreased.The increase of Ni content in the film will lead to the increase of graphitization of the film.It will increase the roughness of the film,but the binding force between the film and the substrate increased gradually.The hardness and elastic modulus of Ni-DLC films prepared with a nickel target power of 10 W are significantly higher than those of other films,and the friction coefficient of the film in seawater is also lower than that of other films.Increasing the power of the nickel target will increase the bond strength of the film,but the hardness and elastic modulus of the film will decrease.At the same time,the corrosion resistance of the film in seawater will decrease.