| Modern high-speed cutting technology puts forward higher requirements for cutting tools.Hard coating deposition on cutting tools is an important method to boost the comprehensive mechanical properties and prolong the cutting life of cutting tools.The cathodic arc ion plating technology has become the main method for preparing coatings in the industry due to its high ionization rate of evaporated particles,strong adhesion between film and substrate,as well as high deposition efficiency.At present,the means of coatings prepared on high-speed steel cutters in the industry are mainly CrAlN coatings.However,in the process of coating deposition,the performance of the coating prepared by different deposition processes is quite different.So it is of great significance to explore the mechanism of coating preparation process on the performance of the coating.In this paper,different CrAlN coatings and CrAlSiN coatings are prepared on high speed steel substrates by glow plasma cleaning plus metal ion bombardment and argon ion etching.The microstructure,mechanical properties,phase structure and corrosion resistance of the coatings are compared and further analyzed.To investigate the effects of different deposition processes on the properties of coatings,the actual service life of the coatings is traced and analyzed.On the basis of the influence of different deposition processes on the coating properties,the CrN/CrAlN multi-layer coating,CrAlN/CrAlSiN multi-layer coating and CrAlN/Ti Al N multi-layer coating are prepared by argon ion etching process to further study the performance of the multi-layer coating.The cutting experiments of the coated tools are carried out,and then the service life of the cutting tools is further tracked.The experimental results show that:Compared with the glow plasma cleaning and metal ion bombardment process,the number of larger particles and pits on the surface of CrAlN coating and CrAlSiN coating prepared by argon ion etching process can be significantly reduced,and the surface quality is also improved.The EDS test results of the coating composition and the larger particle composition of the surface indicate that the percentage of the atomic atoms of the coating element are substantially the same as the atomic percentage of the element in the alloy target,and the proportion of the N element in the larger particle is relatively high.Argon ion etching makes the surface of substrate possesses more micro-defects and nucleation positions,and promotes the formation of a larger number of fine grains,which is conducive to improving the film hardness and adhesion.The corrosion resistance test of 3.5% Na Cl solution shows that the coating prepared by the argon ion etching process possesses less surface defects,meanwhile,the corrosion current density is reduced and the corrosion resistance of the coating is improved to a certain extent.Compared with the CrAlN coating,the doping of Si element in the CrAlSiN coating improves the grain refinement and compactness of the coating,which is manifested by the improvement of the hardness and wear resistance of the coating,as well as the decrease of the friction coefficient.The results of phase testing on CrAlSiN coating show that only CrN and Al N phases are detected in the CrAlSiN coating,and no nitride diffraction peaks of any Si element are detected.It is inferred that the nitride of Si exists in the coating in amorphous form.The cutting experiment of high-speed dry-cutting gear on powder metallurgy high-speed steel hob shows that the service life of the cutting tool is greatly improved by CrAlSiN coating when the cutting speed is increased.The corrosion resistance experiment under condition of CrN/CrAlN multilayer coating,CrAlN/CrAlSiN multilayer coating and CrAlN/Ti Al N multilayer coating in 3.5% Na Cl solution by argon ion etching process shows that: the corrosion current density of the three coatings is much lower than that of the single layer coating.And the CrN/CrAlN multilayer coating has the lowest self-corrosion current density and the best corrosion resistance.The hardness test results show that the CrAlN/CrAlSiN multilayer coating has the highest hardness,while the tribological properties test results show that the CrAlN/CrAlSiN multilayer coating has the lowest friction coefficient,and the coating has stronger chip removal ability and wear resistance.The film bonding strength test results show that the CrN/CrAlN multilayer coating has the highest critical load failure and the best coating adhesion. |
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