| Metal nitride coating is a kind of coating material that is widely used in surface treatment of cutting and forming molds.With the development of modern processing industry,especially the progress of high-speed and dry cutting technology,it put forward higher requirements for cutting tool coating.The requirement of reducing the friction coefficient while maintaining the high hardness of nitride can effectively prolong the service life of coating tools.Therefore,it has been a hot topic to prepare metal nitride coatings with high hardness and low friction coefficient in recent years.Since molybdenum nitride coating have exhibit lower COF because it can generate a Magneli-phase oxide in frictions.Therefore,the metal nitride nano-multilayer film containing Mo element has become a research hot spot due to its high hardness and low friction coefficient.In this paper,TiAlN/Mo2N nano-multilayer films was prepared by closed-field unbalanced magnetron sputtering ion plating technique with different modulation periods and different modulation ratios.We studied the TiAlN/Mo2N nano-multilayers that the changes of modulation period and modulation ratio for the effects of microstructure,mechanical properties,and friction and wear properties,on the harden mechanism and friction-wear mechanism of TiAIN/Mo2N nano-multilayers were discussed.The results show that:TiAlN/MO2N nano-multilayers with different modulation periods and different modulation ratios are composed of face-centered cubic TiAIN and face-centered cubic Mo2N.There is lattice mismatch(f=2.8%)at the interface between the TiAIN layer and the Mo2N layer,forming a coherently epitaxially grown superlattice structure.Compared with TiAlN films,TiAIN/Mo2N multilayer films with different modulation periods have higher hardness and lower friction coefficient.With the increase of the modulation period,the hardnes.modulation period.The value of friction coeff-icient is between 0.28 and 0.31.With the increase of the modulation ratio,the TiAlN/Mo2N nano-multilayer film has obvious preferential growth along the(111)plane.The hardness of the multilayer film increased first and then decreased,and when the modulation ratio was 1:0.8,the maximum hardness value is 40.0±0.9GPa;the friction coefficient decreases first and then increases slightly;when the modulation ratio is 1:2.8,the nano-multilayer film has the lowest friction coefficient,which is 0.24.The TiAlN/Mo2N nano-multilayers with different modulation periods and different modulation ratios are abrasive wear and oxidation wear at room temperature.The higher hardness can effectively reduce the adhesion effect.The high hardness and low friction coefficient improve the wear resistance of TiAlN/Mo2N nanomultilayers.When the test temperature is 400?,the friction coefficient of nanomultilayers is about 0.7,the TiAlN/Mo2N nano-multilayer film is mainly abrasive wear and oxidation wear;when the test temperature is further increased to 600?,the TiAlN/Mo2N nano-multilayer film has the lowest friction coefficient,the value is less than 0.2,and the wear mechanism is mainly adhesive wear and oxidation wear,at the sametime there is a certain amount of abrasive wear.In the range of 25??600?,the wear rate of nano-multilayers gradually increases with the increase of temperature. |
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