Structures,Tribological And Corrosion Properties Of CrN-based Coatings In Sea Water

In this paper,the unbalanced magnetron sputtering and atomic layer deposition?ALD?equipment were used to prepare the film on 45 steel,316L stainless steel and single crystal silicon wafer.After the preparation of the film,the roughness,film-based bonding force,hardness and elastic modulus of the films were tested by three-dimensional shaper,scratch tester and nanoindenter.The surface and cross-sectional morphologies of the films were observed and analyzed by SEM.The metallographic structure and composition of the film were analyzed by X-ray diffractometer and X-ray photoelectron spectroscopy.The corrosion resistance of the prepared film was studied by electrochemical workstation in artificial seawater solution.The tests included open circuit voltage,AC impedance and polarization curves.After the electrochemical tests,the surface morphology of the film was also observed by metallographic microscope.The tribological properties of the film were tested by a ball-disk friction and wear tester.After the friction tests,the metallographic microscope and the three-dimensional shape analyzer were used.Cu-doped CrBN coatings were deposited by unbalanced magnetron sputtering.As the Cu target power increases from 40 W to 100 W,the Cu content increases from 1.83 at.%to 24.68 at.%.From the XRD pattern,it can be found that CrN in the film preferentially grows along the?200?direction.After doping a certain amount of Cu element,the particle size on the surface of the film decreases.The crystal grains are refined,leading to the increase of the surface quality.As increasing the Cu content,the hardness of the film shows a downward trend.The cracks of the film decreases,the toughness of the film increases.Additionally,the average steady-state friction coefficient and wear rate of the film show a trend of decreasing first and then increasing.Among them,CrCuBN-2 film has the best wear resistance.CrN/TiN/CrN composite films were prepared by a hybrid process of magnetron sputtering and ALD.The single CrN film has large crystal grains and high surface roughness.The CrN/TiN/CrN composite film coated with the intermediate layer has fine grain surface,reduced surface roughness and improved surface density.With the increase of the thickness of the intermediate layer,the surface particle size of the CrN/TiN/CrN composite film gradually decreases,the surface roughness decreases,the surface density becomes higher.Meanwhile,the hardness,H/E and H³/E² of the film also gradually increases,as well as increased adhesion strength.In the artificial sea water solution,the CrN/TiN/CrN composite film has a lower average steady-state friction coefficient and wear rate than the bare CrN film.Compared with CrN film,CrN/TiN/CrN composite film also delivers excellent corrosion resistance in artificial sea water solution.CrN/MeO_x/CrN composite films were prepared by a hybrid process of magnetron sputtering and ALD.The intermediate layers such as TiO₂and HfO₂for the composite film are amorphous,in which TiO₂ and HfO₂ present in the form of Ti-O and Hf-O bonds,respectively.The surface particles of the CrN/TiO₂/CrN and CrN/HfO₂/CrN films with a single middle interlayer are relatively large.Their surface roughnesses are high with poor surface quality.By contrast,the CrN/L-Ti-Hf-O/CrN film has the smallest surface particle size,lowest roughness,as well as the highest hardness.In the artificial sea water solution,the CrN/L-Ti-Hf-O/CrN film shows the best wear resistance including lowest average steady-state friction coefficient and wear rate,due to its good mechanical properties.In addition,CrN/L-Ti-Hf-O/CrN also delivers excellent corrosion resistance owing to the synthetic effect of the good chemical stability of TiO₂ and high passivation barriers of HfO₂.