| Thin film technology has been widely used in semiconductor,surface protection,optical devices,decoration and other industries.In the manufacturing industry,the application of film technology can significantly improve the comprehensive performance of cutting tools.The service life of cutting tools can be prolonged by 2~3 times,and the production efficiency is improved.Compared with TiN films,ZrN films have higher hardness and better wear resistance.Due to the low toughness,ZrN and other ceramic films can not be used under dynamic loads for long time.Nano-multilayer films have periodic multilayer structure,a large number of interfaces can hinder the movement of dislocations and propagation of crack,which leads to good mechanical properties.In order to realize the strengthening and toughening of film material,ZrN/CrAlN multilayer films with different modulation period,ZrN/VN multilayers with different modulation ratio were deposited on silicon wafer and stainless steel at different temperatures by unbalanced reactive magnetron sputtering.To characterize the morphology and structure of the films,field emission scanning electron microscopy and X-ray diffractometry were used.Surface profiler was used to measure the films' roughness and thickness.Nanoindentation was used to test the films' hardness and elastic modulus.Automatic scratch tester was used to measure film critical loads.We characterized the toughness of the films by CPR(crack propagation resistances).The fracture toughness KIC of the films was calculated by using the micro indentation method.Ball-on-disc tribo-tester was used to characterize the tribological properties of films.ZrN/CrAlN nano-multilayers' sections are transgranular columnar structure.When the modulation period is 20 nm,the distinction between layer and layer is clear.The surface of nano-multilayers are dense like the cauliflower.The thickness of nanomultilayers are about 2 microns.When the modulation period is 8 nm,the hardness is 20.4 GPa.Further increasing the modulation period,the hardness decreased.The Critical load Lc2 is 18 N,CPR number is 73.2,when the modulation period is 8 nm.The nanomultilayer's Critical load Lc2 and CPR number are higher than other nano-multilayers.At The critical load Lc2,the coating has been peeled off as the result of crack propagation.And the bright white hot rolled steel substrate was exposed,the nano-multilayers lost the protective effect to substrates.Changing the modulation period will affect the nanomultilayer coating's toughness under the condition that keeping the multilayer coat's thickness and modulation ratio invariable.With the increase of modulation period,toughness properties have been improved then descended.The film has the highest hardness and toughness and gets the best comprehensive performance when the modulation period was 8 nm.ZrN/VN nano-multilayer films show dense columnar structure.ZrN/VN nanomultilayer film obtains the maximum hardness of 45.4 GPa and the maiximum plastic deformation resistance characteristics H3/E*2 of 0.38 GPa at ZrN/VN modulation period of 10.4 nm.The multilayer coating's wear rate decreases with modulation period increasing at room temperature,the ZrN/VN nano-multilayer coating gets the minimum wear rate of 6.22 × 10-7 mm3/Nm when the modulation period is 12.2 nm.The multilayer film achieves a relatively well tribological property tested at 400 oC when the modulation period is 10.4 nm,and the wear rate is 8.70 × 10-7 mm3/Nm.It is attribute to the high hardness valve and the self-lubricant effect of VN.In the 700 oC friction and wear test,due to the difference coefficient of thermal expansions between film and substrate,the film substrate binding force decreased,and the multilayer film was quickly peeled off,so the substrate lost the protection of film.This study provides a method for the structural design,preparation and characterization of hard films,and it also provides a new concept and feasibility path for the strengthening and strengthening of thin film materials. |
PDF Full Text Request