Structre And Properties Of TiN/NbN Nano-muiltilayer Hard Films

In recent years,with high hardness and modulus,high thermal stability and corrosion resistance hard nano-multilayers get a lot of attention,and TiN/NbN multilayers which has the same coefficicnt of thermal expansion as the widely used tool steel become a research hotspot.In this thesis,TiN/NbN nano-multilayer films was prepared by magnetron sputtering technique with different modulation cycle and different modulation ratio,and through microstructure,mechanical and tribological properties of research,we analyzed the relationship between the structure and properties of TiN/NbN nano-multilayer films in different modulation cycle and modulation ratio.The results show that:TiN/NbN nano-multilayer film under different modulation cycles mainly consisting of face-centered cubic TiN and face-centered cubic NbN.Since the fine grains and micro-strain,nano-multilayers diffraction peaks appeared wide phenomenon.TiN/NbN multilayers with good periodic layered structure,when the modulation period is less than 2.3 nm.Layer blurred.Since the crystal plane atoms have diffficult in passing through the interface layer along(111)or(200)plane to achieve coherent epitaxial growth result in grain refinement.With the increase of modulation period,the hardness of the multilayer film first increases and then decreases.When the modulation period of 7.1 nm,TiN/NbN nano-multilayer films exhibit superhard effect.maximum hardness for 43 GP,elastic modulus highest 465.2 GP.A fter TiN/NbN multilayers of different modulation cycle's friction and wear were tested we found that TiN/NbN multilayers overall friction coeffficient is too large,above 0.8,exhibit poor wear resistance,wear mechanism is mainly abrasive wear and fatigue wear.When the modulation period A= 1.9 nm,with a multilayer film that toughness,combined with better adhesion strength,exhibit the best wear property.TiN/NbN nano-multilayer film of different modulation ratio using different Nb target currents consisting essentially of face-centered cubic phases of TiN and NbN,NbN thin film made of a variety of complex phase structure.As Nb target current increases,the diffraction peak shifts gradually to NbN phase's diffraction peak,the preferred orientation of TiN/NbN multilayers transform from the(111)plane to the(111)and(200)planes,film layered modulation structure has become increasingly evident.With the increase of Nb target current modulation interface become apparent.Since the modulation layered structure becomes apparent,TiN/NbN multilayers'hardness gradually increase as the Nb target current increases,rising from 30 GP to 34 GP.The TiN/NbN nano-multilayer film of different modulation ratio using different Nb target currents consisting essentially of face-centered cubic phases of TiN and NbN,NbN thin film made of a variety of complex phase structure.As Nb target current increases,the diffraction peak shifts gradually to NbN phase's diffraction peak,the preferred orientation of TiN/NbN multilayers transform from the(111)plane to the(111)and(200)planes,film layered modulation structure has become increasingly evident.With the increase of Nb target current modulation interface become apparent.Since the modulation layered structure becomes apparent,TiN/NbN multilayers' hardness gradually increase as the Nb target current increases,rising from 30 GP to 34 GP.The NbN film because of its special phase structure,hardness up to 39 GP.The coefficient of friction of TiN/NbN multilayers with different Nb target current are higher than TiN and NbN single film.In addition to the wear resistance of TiN film is relatively good,the friction and wear properties of TiN/NbN nanomultilayers and NbN film is poor,which is due to a variety of mechanisms such as fatigue wear,oxidation wear,abrasive wear,etc.