Study Of Properties On TiCN Hard Composite Coatings Deposited By Multi-arc Ion Plating

With the rapid development of manufacturing industry and cutting technology,it proposes more stringent requirements for the hard coatings deposited on the surface of the tool.Traditional dualistic coatings such as TiN and CrN cannot meet the needs of society.At present,hard coatings can be devided into various kinds.Among these hard coating materials,TiCN,produced by TiN and C,shows potential in improving the performance of the cutting tools for their high mechanical properties,abrasive resistance,chemical and thermal stability.TiCN is also one of the hotspots in research of hard coating field.However,there are still some problems during the development of TiCN,for example,lack of mechanism analysis,incomplete process optimization,inadequate mechanical properties of TiCN matrix composite or multilayer coatings.This work focuses on TiCN and plans to prepare TiCN and TiCN matrix composite multilayer coatings by multi-arc ion plating technique,explore the effect of process and coating structure on the properties of TiCN,in order to obtain coating with excellent comprehensive properties based on TiCN and better applied to industrial production.(1)The effect of carbon on the properties of TiCN coating was studied.With varing the C2H2 flow rate,carbon content(mass percentage)increases from 19.09%to 31.52%.The number of large particles on the surface of TiCN decreases with the increase of C2H2 flow,but surface microcracks increase when the C2H2 is too high.Typical columnar morphology is observed in coating's cross section from SEM observation.TiCN(111)peak has obvious intensity advantages in XRD patterns,while TiN(111)is shifted to TiC(111)with the increase of C2H2 flow,which reflects the increase of TiC produced by replacement of carbon atoms and nitrogen atoms.Hardness and adhesion of TiCN firstly increase and then decrease with the increase of C2H2 flow.Their maximum value of(33.65±0.36)GPa and(34.52±0.35)N are relized when C2H2 flow is 100 seem and 120 seem,respectively.Wear resistance shows similar changes with adhesion,the mean friction coefficient reaches minimum of 0.315 at C2H2 of 100sccm.In conclusion,TiCN coating has best properties at C2H2 flow of 100sccm in which the carbon content is 24.81%.(2)The pulsed magnetic field is introduced to reduce the number of large particles.The field current varies from 0A,2A,4A,6A to 8A.The corresponding magnetic induction intensity at arc target is 0 mT,0.74 mT,1.48 mT,2.21 mT and2.94 mT.The number and scale of large particles on TiCN's surface were counted and areal density of particles is lowest when current is 6A.With pulsed magnetic field,particles larger than 1.2 ?m are fully eliminate.The arc light shrinks caused by pulsed magnetic field so that arc target is fired equably and the production of large particles is restrained.All XRD patterns of samples only show peak(111).The hardness of TiCN improves with increase of current and reaches maximum of(33.90±0.29)GPa.Adhesion and wear resistance firstly increase and then decrease,because internal defects of coatings increase caused by large particles and the interface binding force is reduced.The coatings show best properties under condition of 6A and 2.21mT,whose adhesion is(35.41±0.31)N and mean friction coefficient is 0.324.(3)The interlayers of Cr series were introduced to prepare composite coatings based on TiCN.The section morphology of coatings change from columnar crystal to flaky crystal and eventually the isoaxial nanocrystal appears with change of interlayers.The XRD patterns are significantly changed,intensity of peak TiCN(111)greatly decrease and even lower than that of(200),coatings lose preferred orientation of(100)and diffraction peak broadening.Mechanical properties and wear resistance of TiCN improve with interlayers add in sequence Cr,CrN and CrCN,TiCN coating with interlayer of Cr+CrN+CrCN shows best properties whose hardness is(30.11±0.34)GPa,adhesion is(37.21±0.46)N and mean friction coefficient is 0.111 The lattice mismatch of interlayer and coating restrains preferred growth of columnar crystals and the coating compactness is improved,especially the coating with multilayer composite structure formed by adding CrCN into the interlayer obtains excellent wear resistance.(4)TiCN/CrCN nano-multilayer film was successfully prepared.The period was changed by adjust the revolution of frequency of matrix,periods are respectively 50,100,150,200 and 250,the modulation periods are respectively 34.80nm,20.13 nm,14 nm,9.75 nm and 6.12 nm.Clear layering and continuous interface were observed in section sectional topography which proves successful preparation of nano-multilayer structure.Peaks TiCN(111),TiN(222),(Ti,Cr)N(200)and(220)are observed in XRD patterns of all samples and the intensity weakens with decrease of modulation period.The change of adhesion is not obvious and maximum is(37.47±0.311)N.The hardness abnormal increases under modulation period of 14nm and 9.75nm,the maximum hardness reaches(39.54±0.32)GPa and super hard effect may occurs within this interval.In the paper,some major theories about mechanisms of nano-multilayer film's super hard effect were summarized divided into crystal/amorphous structure and crystal/crystal structure.The nano-multilayer film's wear resistance is significantly higher than that of other tests,the mean friction coefficients are all less than 0.25.The toughness is improved for existence of lots of interfaces,meanwhile nano-multilayer film has effect of super hard,the joint effect of hardness and toughness achieve the best under modulation period of 14nm,the mean friction coefficient reaches minimum of 0.139.