Research On Microstructure And Friction-wear Properties Of AlCrN Coating By Cathodic Arc Plating

This topic comes from the Science and Technology Support Program of Jiangsu Province?Industry??BE2012066?:Research on the key precision manufacturing technology of ultra large ring gear in aviation large-scale CNC equipment,putting forward that using AlCrN cutting tool coating can improve the efficiency and accuracy of machining.TiC and TiN coatings have been used widely,AlCrN coating has high hardness and low friction coefficient,it also can withstand 900¹000?,At present,there are few systematic studies on the micro-morphologies,bonding mechanism,wear properties of AlCrN coating,this paper has a deep study on the microstructure,compositions and properties,providing a reference for enhancing the application level of AlCrN coating cutting tools.The main conclusions and innovations are as follows:?1?AlCrN coating was prepared on the TiC-based tool by cathodic ion plating,AFM was used to observe micro-topographies,the surface roughness evaluation parameters were obtained.The results show that:the coating has a dense,relatively flat surface and tight bond with the substrate.Roughness Sa of substrate and coating are 63.7 and 135nm;coating surface height is relatively dispersed,and has a bigger surface bearing index;the average particle diameter of AlCrN coating and TiC-based substrate is 710nm and1460nm;power spectrum distributions of coating and substrate are irregular,the surfaces show anisotropy.There is no definite relation between the surface profile of coating and substrate.?2?Compositions and surface-interface chemical elements distributions of AlCrN coating were analyzed by SEM,XRD and EDS,and the interface metallurgical bonding mechanism are discussed.The results show that:there are AlN,CrN,a small amount of TiC?N?and Ni in the coating;the AlCrN coating surface has high content of Al,improving wear resistance;metallurgical combination is formed in the interface,diffusion occurs mainly among Ti,C,N and Al,the binding strength is 83N.?3?Friction-wear test was used to study the friction factor and wear mechanism of TiC-based metal ceramic cutter and AlCrN coating.The results show that:the friction factor of AlCrN is 25%smaller than TiC-based substrate,with the increase of the load,the friction factor decreases;TiC-based metal ceramic tool wear mechanism is fatigue wear+abrasive wear+oxidation wear,Wear mechanism AlCrN coating is abrasive wear+oxidation wear.?4?High temperature oxidation resistance of AlCrN coating was investigated by high temperature oxidation test,X-ray photoelectron spectroscopy?XPS?was used to analysis the bonding energy of each elements.The results showed that:After 900?high temperature oxidation,AlCrN coating surface was completely oxidized,generating stable Al₂O₃ and Cr₂O₃,which have a protective effect on the cutter substrate;XPS results of AlCrN coating before and after oxidation both showed the presence of Al2p peek,Cr2p peek,C1s peek,N1s peek,O1s peak;before oxidation,the bonding energy of Al2p is 74.3eV,corresponding to Al-N bond;the bonding energy of Cr2p3/2 peek and Cr2p1/2 peek is 578.3eV and 587.0eV,respectively,which is related to Cr-N;the bonding energy of N1s is 400.0eV;after oxidation,Al2p bonding energy is 74.3eV,which is related to Al-O and Al-Al bond,the bonding energy of Cr2p3/2 and Cr2p1/2 are 576.9eV and 587.3eV,respectively,which is related to Cr-O bond,the binding energy of N1s is400.0eV.The bonding energy of Cr2p1/2 which is related to Cr³⁺increases by0.3eV after oxidation,which is caused by the higher electronegativity of O element than N element.?5?900?high temperature wear test was used to study the of friction-wear behavior of the coating.SEM was used to observe wear morphologies.Compositions and phases before and after wear are analyzed by EDS and XRD,the effects of load on the wear resistance and friction factor of the coating are discussed.The results show that:after 900?oxidation,AlCrN coating was oxidized into Al₂O₃ and Cr₂O₃,the average friction factor were 0.146,0.394,0.419 under load of 600g,800g and 1000g,respectively;a lot of oxides generated after high temperature oxidation,the wear mechanism is oxidation wear+abrasive wear+adhesive wear.