Structure And Cavitation Erosion Resistance Of TiSiN/NiTiAlCrCoN Nano Multilayer Films

The blades of steam turbines and propeller in large shape often fail due to cavitation erosion,which seriously affects the service life of the blades.Therefore,developing a cavitation coating with excellent performance and low price is one of the effective methods to solve the problem of blade cavitation.High entropy alloy nitrides have excellent corrosion resistance and cavitation erosion resistance.The study of their microstructure,cavitation resistance and cavitation mechanism will provide a theoretical basis for the design of cavitation erosion resistance coatings.NiTiAlCrN coatings with different nitrogen and argon flow ratios,NiTiAlCrN,NiTiAlCrCoN,NiTiAlCrCo Mo N coatings with different element components,NiTiAlCrCoN coatings with different Co contents and Ti Si N/NiTiAlCrCoN nanomultilayer with different modulation periods were prepared by multi-target magnetron sputtering.X-ray diffractometer(XRD),scanning electron microscope(SEM),and energy dispersive spectrometer(EDS)were used to analyze the structure of the films.Nanoindenter,scratch instrument,and ultrasonic cavitation test machine were used to characterize the properties of the films.The cavitation erosion resistance of high entropy alloy nitride was studied.The main research contents are as follows:(1)The effect of nitrogen-argon flow ratio on the microstructure and cavitation erosion resistance of NiTiAlCrN film was studied by changing the flow of nitrogen and argon.When the nitrogen-argon flow ratio is 1:2 and 3:2,films exhibit a preferred orientation on(111)and(200)crystal planes.When the ratio is 1:1,film has a preferred orientation on(111)crystal plane.The diffraction angle of(111)crystal plane shifts to a small angle with the increase of nitrogen-argon flow rate.When the flow ratio is 1:1,the NiTiAlCrN film has the best cavitation erosion resistance,the best mechanical properties and the highest degree of crystallinity.(2)The effect of element composition on the microstructure and cavitation erosion resistance of the film was explored by changing the target material composition.The films exhibit the preferred orientation on the(111)and(200)crystal planes.The addition of Co and Mo elements shifts the diffraction angle of the(200)crystal plane to a small angle,and the addition of Co elements weakens the(111)diffraction peak significantly.The NiTiAlCrCoN film has the best cavitation erosion resistance,the best crystalline state,and the best toughness and bonding force.(3)The effect of Co content on the microstructure and cavitation erosion resistance of NiTiAlCrCoN films was studied by changing the molar ratio of Co in the target.The films with different Co content have a preferred orientation on the(200)crystal plane,and the diffraction angle of the(200)crystal plane shifts to a small angle with the increase of Co content.The films with equal molar ratios have special microstructure and mechanical properties.The film with a Co molar ratio of 1.4 has the best cavitation erosion resistance and the least defects.(4)The effect of the modulation period on the microstructure and cavitation erosion resistance of the nano multilayer film was studied by changing the deposition time of the NiTiAlCrCo target.The nano multilayer films with different modulation periods exhibit a preferred orientation on the(200)crystal plane.With the increase of the modulation period,the diffraction angle of the(200)crystal plane firstly shifts to smaller angle and then to bigger angle.When the modulation period is 11 nm,the diffraction angle is the largest,and the crystal plane spacing minimum.When the modulation period is 11 nm,the film has the best mechanical properties,the best cavitation erosion resistance and the least defects.