Study On Preparation And Properties Of TiA1N Films By Intermediate Frequency Unbalanced Magnetron Sputtering

TiAlN hard films have more excellent properties than TiN films, such as: high hardnessand oxidation temperature, good corrosion resistance and abrasion resistance, etc. Therefore,TiAlN films have broad application prospects in the field of cutting tools and moulds.In this paper, TiN and TiAlN films were successfully prepared on the YG6cementedcarbide substrate by the intermediate frequency unbalanced magnetron sputtering ion platingtechnology, and their main properties were tested and analyzed. The relationship between thefilms’ compositions, surface morphology, microstructure, properties and the processingparameters (target power, substrate bias, N2partial pressure, substrate temperature, depositiontime) were mainly studied.XRD analysis showed: TiN film had face-centered cubic structure, along the (111) planepreferred orientation. TiAlN films mainly had a wurtzite hexagonal structure Ti3AlN phase,along the (220) plane preferred orientation and the diffraction peaks were shifted to thehigh-angle region. In addition, there were AlTi2N and AlN phases with a closed-packedhexagonal structure, TiN and TiC phases with a face-centered cubic structure. Differentprocess parameters, phases’ structure were different.SEM and Fracture morphology analysis showed: TiN film had compact structure, smoothand uniform surface; the film had compact and small grain size, growth in columnar crystal,with a solid link of film-substrate, atoms interdiffusion on the interfaces. Increasing the Altarget current, TiAlN films’ surfaces were smoother and uniform, defects reduced, with amore compact structure and smaller grain size, the films and substrates combined strongly.When the Al current was16A, the film showed a dense columnar structure and high density.Increasing the negative bias, the films’ defects reduced and densities enhanced. When thenegative bias increased to50V, the residual stress increased, the films were severely damaged,the surfaces were roughness and uneven. Increasing the N2partial pressure, the films’roughnesses increased and tissues loosed. Increasing the substrate temperature, atoms had afull reaction, grain refining, the films had dense and smooth surfaces. Increasing thedeposition time, the films’ thickness and the stress increased in the films, a part of the surfaceappeared some spalling phenomenon.EDS analysis indicated: TiN film included Ti and N, Ti/N atomic ratio closed to1.Threekinds of elements (Al, Ti, N) were detected in TiAlN films. Increasing the Al target current,the content of Al atoms increased, but Ti and N atoms decreased in the films. Increasing thesubstrate bias, the content of Al and Ti atoms decreased in the films, the values of Al/(Al+Ti)and (Al+Ti)/N decreased. Because of the sputtering yield of Al atom was about2times of Tiatom, the losses of Al atoms were more than Ti. Increasing the N2partial pressure, the content of Al and Ti atoms decreased and the losses of Al atoms were higher than Ti. Increasing thesubstrate temperature, the content of Al and Ti atoms and the value of (Al+Ti)/N increased inthe films.Binding force and microhardness analysis showed: The film-substrate binding force ofTiN film was41N; the microhardness was2350HV. The value of Ti/N atomic ratio closed to1,generating more Ti-N saturated bonds, with a high microhardness. The binding force of TiAlNfilms was up to78N, microhardness was up to2915HV. Increasing the Al target current, thebinding force and microhardness increased at first and then decreased. Increasing the Al targetcurrent, the films’ defects reduced and grain refinement, density and binding force increased;the interaction of Ti3AlN hard phase, Al atoms substituted the position of Ti atoms caused thelattice distortion and grain refinement improved the microhardness. However, the filmsappeared excessive amorphous AlN soft phases, causing the severe lattice distortion, theinternal stress increased and structure loosed, binding force and microhardness decreased.Increasing the substrate negative bias, the diffusion and migration abilities of particlesimproved, density increased, binding force and microhardness increased; but the negative biaswas too large, the ion etching effect on films were seriously, the films’ structure weredestroyed and films thinning, the binding force and microhardness decreased. Increasing theN2partial pressure, the diffusion and migration abilities of particles declined, the films’ grainsize increased, structure loosed and density decreased, the binding force and microhardnessdecreased. Increasing the substrate temperature, the particles that reached the films gainedmore energy, atomic full reactions that made for the deposition of Ti3AlN phase films,particles’ migration and diffusion capacities enhanced on the surface, grain refinement anddensity increased, the binding force and microhardness improved. Changing the depositiontime, the films’ thickness changed, the binding force and microhardness changed.Deposition rate analysis showed: The thickness of TiN film was2.50μm; the depositionrate was0.50μm/h. The thickness of TiAlN films was up to5μm, the deposition rate reached1μm/h. Increasing Al target current, the sputtering efficiency of Al target improved, thenumber of atoms and energy that reached the films increased, defects reduced, thickness anddeposition rate increased. Increasing substrate negative bias, the thickness and deposition ratepresented firstly increased and then decreased. When the negative bias was too large, the filmswere etched seriously by high-energy Ar+, the thickness and deposition rate decreasedsignificantly. Increasing the N2partial pressure, the proportion of Ar partial pressure decreased,resulted in the sputtering efficiency of metal targets and the number and energy of particlesthat reached the films reduced, the thickness and deposition rate decreased. Increasing thesubstrate temperature, the atoms obtained more energy and were conducive to the depositionof the films, the films’ thickness and deposition rate increased.Film color analysis showed that: When the current of Ti target was24A, TiN film was golden yellow and had a better gloss. Increasing the Al target current, the black AlN phaseincreased in the films, TiAlN films’ color changed from yellow purple to magenta, purpleblack, black, and the gloss decreased. Increasing the substrate negative bias, the lighter atommass of Al atom loosed more than Ti atom in TiAlN films, the films became thinner and thecolor became lighter, the color changed from purple black to magenta, and the gloss enhanced.Increasing the deposition time, the films’ color deepened and gloss reduced.