| Tungsten nitride?W2N?film is a hard transition metal nitride film with excel-lent mechanical properties,which make it be widely used in the field of protective coatings and diffusion barrier coatings.In this thesis,well-crystallized W2N films were successfully prepared on Si?100?and A3O4 stainless steel substrates by RF magnetron sputtering by changing the substrate temperature,sputtering power,argon nitrogen ratio,sputtering pressure and other deposition parameters.The crystal structure,surface morphology,composition,mechanical and tribological properties were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,energy dispersive X-ray spectroscopy?EDX?,nanoindentation and CETR trib,expectively.Firstly.W2N films with good crystallinity were prepared by RF magnetron sputtering,and all the films show the dense,flat and uniform surface and the average grain size of 18-30 nm.The W2N film with the?111?preferred orientation was obtained by controlling the experimental parameters.The optimum preparation conditions are as follows:the substrate temperature of 400 ?,sputtering power of 120 W,argon nitrogen ratio of 20:6,and deposition pressure of 0.5 Pa.The W2N film obtained under the optimum preparation conditions exhibits higher hardness,small elastic modulus and lower wear rate.The film has a hardness of 21.45 GPa,an elastic modulus of 256.34 GPa,and a wear rate of 5.17X 10-6 mm3/Nmm.Then,in order to improve the mechanical and tribological properties of the W2N film,soft metal Y and hard metal codoped W2N?Y-Ti:W2N?films were prepared by RF and DC magnetron co-sputtering.The doping power is increased from 0 W to 50 W.As the sputtering power changes,the preferred orientation of the film changes accordingly.The tungsten nitride film changes from the?111?preferred orientation of the undoped film to the?200?preferred orientation.When the doping power is increased to 50 W,the?200?diffraction peak disappears and the film exhibits an amorphous state.With the incorporation of Y-Ti alloy,the hardness of the film does not change much,but the tribological properties of the film are optimized.When the doping power is 20 W,the wear rate is reduced to 4.094×10-6 mm3/Nmm.The mechanical and tribological properties of Y-Ti:W2N films are better than those of undoped W2N films.Finally,the soft metal Y and hard metal Cr co-doped W2N?Y-Cr:W2N?film was prepared by RF and DC magnetron co-sputtering.As the doping power is increased to 20 W,the preferred orientation of the Y-Cr:W2N film is changed to?200?preferred orientation.When the sputtering power is increased above 30 W,the film exhibits an amorphous state.With the incorporation of metal Y-Cr,the mechanical and tribological properties of the film have been greatly improved.At the doping power of 30 W,the maximum hardness of 23.71 GPa and the maximum elastic modulus of 256.34 GPa are obtained.The film has the minimum wear rate of 2.062 ×10-6 mm3/Nmm at the doping power of 20 W.Compared with Y-Cr:W2N films,the mechanical and tribological properties of Y-Cr:W2N films are enhanced. |
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