Resarch On Microstructure,Mechanical And Tribological Properties Of ZrCN,ZrCn-Ag And ZrMoN-Ag Nanocomposite Films

In this dissertation,a series of ZrCN composite films with different carbon content and a series of ZrCN-Ag films and ZrMoN-Ag films with different Ag content were deposited by the magnetron sputtering system and their microstructure,mechanical and tribological properties were characterized by X-ray diffractometer,Raman spectrometer,atomic force microscope,scanning electron microscopy,transmission electron microscopy,energy dispersive spectrometer,nano-indentation and ball-on disctribo-meter.The conclusions are as follows:(1)The results showed that the deposited ZrCN films consisted of fcc-Zr(111),fcc-Zr(200),amorphous C and amorphous CN_x.According to the first-principles calculations,Carbon elements prefer to replace the zirconium elements in Zr N lattice to form a(Zr,C)N substitutional solid solution.The adhesion between ZrCN film and substrate increases with the increase of C content.The hardness and elastic modulus of the ZrCN films increases first and then decreases with the increase of C content.The maximum value is 30.8 GPa and 298.5GPa at 8.58 at.%C,respectively.The friction coefficient of ZrCN films under room temperature decreases monotonously with the increase of C content,the friction coefficient of ZrCN composite film with Ag content of 25.79 at.%reaching the minimum value of 0.28and The room temperature wear rate of ZrCN composite film first decreases and then increases with the increase of C content.When the C content is 20.54 at.%,the wear rate reaches the minimum value of 5.3×10^-8 mm³·n^-1·mm^-1.The change of friction and wear properties of ZrCN composite film at room temperature is due to the joint influence of mechanical properties and phase composition of ZrCN composite film.(2)The results showed that the deposited ZrCN-Ag films consisted of face-centered cubic(fcc)Ag,fcc-ZrCN,and amorphous graphite and CN_x phases.The hardness and elastic modulus of the ZrCN-Ag films increases first and then decreases with the increase of Ag content.The maximum value is 28.4 GPa and 266.8 GPa at 1.44 at.%Ag,respectively.The mechanical properties of the composite films are mainly affected by residual stress,solid solution strengthening,phase composition and fine grain strengthening.The friction coefficient and wear rate of ZrCN-Ag films under room temperature first decreased and then increased with the increase of Ag content.In the temperature range of 100?500?,the friction coefficient of ZrCN Ag composite film with Ag content of 10.29 at.%,increases gradually with the increase of temperature,which is related to the mechanical properties and Ag migration consumption of Zr O₂produced in the friction process;with the increase of temperature,the wear rate of the film increases gradually,which is related to the adhesive wear of soft phase Ag at high temperature and the formation of Ag O in the friction process,Ag O,Ag₂O,Zr O₂ and Zr₃O are related.(3)ZrMoN-Ag films consisted of fcc-Mo₂N,fcc-Zr N,and fcc-Ag phases.With the increase of Ag content,According to the first-principles calculations,Mo elements prefer to replace the zirconium elements in Zr N lattice to form a(Zr,Mo)N substitutional solid solution.the hardness and elastic modulus of the film first increased and then decreased.When the Ag content was 3.15 at.%,the hardness and elastic modulus of the film reached the maximum values with 27.6 GPa and 286.8 GPa.At room temperature,with the increase of Ag content,the friction coefficient of ZrMoN-Ag composite film increases first and then decreases,the wear rate first decreases and then increases.When the Ag content is 11.88 at.%,The addition of Ag can reduce the friction coefficient of the films from RT to 600?,and the friction coefficient reaching the minimum value of 0.197 at 600?.At the same temperature,the friction coefficient of the ZrMoN-Ag composite film was smaller than the ZrMoN film.The wear rate of ZrMoN-Ag composite film increases with the increase of temperature.The results show that the wear rate of ZrMoN-Ag composite film increases with the increase of temperature,which is due to the diffusion of Mo O₃,Ag O,Ag₂O,Ag₃O₄ and Zr O₂ oxidation phase generated by friction at high temperature and the wear of soft phase Ag.the addition of Ag can improve the friction and wear properties of ZrMoN-Ag films at medium and high temperature.