Effect Of Cu And Ag On The Microstructure,Mechanical And Tribological Properties Of ZrN And TaVN Based Films

Transition metal nitride(TMN)films occupy an important station in some areas such as cutting and die tools due to their excellent mechanical and tribological properties.The ZrN and TaVN films were chose in my thesis with a purpose of improvement of the tribological properties at wide temperature range.Noble metal Cu,Ag were added with a purpose of improvement of the tribological properties at varied temperatures.The aim of my thesis was the design of a new TMN system with excellent tribological properties at varied temperatures.A series of ZrN-Cu composite films with different Cu content,a series of ZrN-Ag composite films with different Ag content,a series of TaVN-Ag films with different Ag content were deposited using the RF magnetron sputtering system.The microstructures,mechanical properties and tribological properties of the films were investigated by XRD,SEM,EDS,HRTEM,nanoindentation,ball-on-disc tribo-meter,3-D profilometer and Raman.The results are as follows:The research of ZrN-Cu composite films shows that the ZrN-Cu films were composed of face-centered cubic(fcc)-ZrN and face-centered cubic(fcc)-Cu and grow optimally along(111)crystal surface.With the increase of Cu content,the hardness of ZrN-Cu composite film increased firstly and then decreased.The hardness reached the maximum value was about 34.6 GPa at 16 at.% Cu.At room temperature,the coefficient of friction of ZrN-Cu films were lower than that of the ZrN film.When the content of Cu was lower than 39 at.%,the wear rate of ZrN-Cu films were lower than that of the ZrN film.When the temperature of tribological testing during 200-700℃,the Cof.of ZrN-Cu films at 16 at.% Cu were lower than that of ZrN film,while the wear rate were higher than that of the ZrN film.In summary,the hardness and tribological properties of the ZrN-Cu film is improved at room temperature by adding Cu,and the coefficient of friction of the ZrN-Cu decreases when temperature is between 200 and 700℃ ℃.The research of ZrN-Ag composite films shows that the ZrN-Ag films were composed of face-centered cubic(fcc)-ZrN and face-centered cubic(fcc)-Ag and grow optimally along(111)crystal surface.With the increase of Ag content,the hardness of ZrN-Ag composite film increased rapidly and then decreased rapidly.The maximum hardness value was about 22.8 GPa at 6.1 at.% Ag.At room temperature,the coefficient of friction of ZrN-Ag films were lower than that of the ZrN film,and the coefficient of friction of ZrN-Ag films decreased gradually with the increasing of Ag.After testing the tribological properties at high temperatures,when the temperature become higher,more Ag diffused to the surface of ZrN-Ag film.When the temperature of tribological testing during 200-500℃,the coefficient of friction of ZrN-Ag films at 29.17 at.% Ag were lower than that of the ZrN film,while the wear rate were higher than that of the ZrN film.In summary,the hardness of the ZrN-Ag film is improved at room temperature by adding Ag,and the coefficient of friction of the ZrN-Ag decreases when temperature is between 25 and 5℃ 00℃.The research of TaVN-Ag composite films shows that the TaVN-Ag films were composed of face-centered cubic(fcc)TaVN and fcc-Agand grow optimally along(200)crystal surface.With the increase of Ag content,the hardness of TaVN-Ag composite films first increased and then decreased rapidly.The maximum hardness value was about 31.4 GPa.At room temperature,the coefficient of friction of TaVN-Ag films were lower than the TaVN film,and the coefficient of friction of TaVN-Ag films decreased gradually with the increasing of Ag.The the coefficient of friction of the TaVN-Ag film with 7.93 at.% Ag was lower than that of the TaVN film,and their wear rates showed opposite trends with increasing temperature.For the TaVN-Ag films with 7.93 at.% Ag,the the coefficient of friction first increased gradually and then decreased rapidly during 25°C-600°C,whereas the wear rate of the film increased continuously.The coefficient of friction of the TaVN-Ag film with 7.93 at.% Ag was lower than that of the TaVN film,and their wear rates showed opposite trends with increasing temperature.In summary,the hardness of the TaVN-Ag film was improved at room temperature by adding Ag,and the coefficient of friction of the TaVN-Ag decreases when temperature is between 25 and 600℃ ℃.