Discharge Characteristics Of Magnetic Field Enhanced High Power Impulse Magnetron Sputtering And Preparation Of TiAlN Films

TiAlN films are widely used as the tool coating because of high hardness,resistance to friction and abrasion and high corrosion resistant. For conventionalmagnetron sputtering technology, the adhesion between film and substrate is poor,sputtered particles mostly exist in atomic state due to the ionization rate is lowerthan10%. High power impulse magnetron sputtering technique is an excellentmethod for preparation of TiAlN films featured by high peak power density leadingto high ionization rate.Auxiliary magnetic field was used to improve the degree of ionization, and thedischarge characteristics of magnetic field enhanced high power impulse magnetronsputtering of TiAl target was researched. TiAlN films were deposited on M2highspeed steels, and the effect of coil current, discharge current, Ar/N2flow ratio andworking pressure on the morphology, composition, phase structures, micro-hardness,wear resistance and scratch load of deposited films were researched.The results related to the plasma discharge characteristics show that auxiliarymagnetic field can significantly improve the substrate current. Target current andsubstrate current increase with increasing working pressure and discharge voltage,decrease with the increase of hybrid DC current. Compared with discharge of pureAr gas, target current and substrate current significantly increase due to the increaseof the number of secondary electrons because of the presence of N2. Target currentand substrate current increase rapidly and then keep constant with increasing the N2flow.The surface roughness of the smooth TiAlN films which were fabricated bymagnetic field enhanced high power impulse magnetron sputtering is between4nmand10nm. The structure of TiAlN films is columnar crystal, and the Al/Ti atomicratio is more than1.7in TiAlN films deposited by different parameters. Al/Tiatomic ratio increases first and then decreases with increasing coil current, N2flowand working pressure, increase with the increase of discharge current. TiAlN filmsmainly contain TiAlN(200) and TiN(220) diffraction peaks, AlN(1010) diffractionpeak also appears in TiAlN films.The results show that auxiliary magnetic field can significantly improve thenanohardness and elastic modulus of TiAlN films, nanohardness and elasticmodulus can be up to32GPa and391GPa. The minimum friction coefficient ofTiAlN films is0.25, so TiAlN films have good performance of resistance to frictionand abrasion. The effect of coil current on resistance to friction and abrasion issignificant, the coefficient of friction decreases greatly with increasing coil current.TiAlN films have perfect adhesion which is more than50N, and the adhesion increases with the increase of coil current. The adhesion increases first and thendecreases with increasing discharge current and working pressure, and alsodecreases with increasing N2flow.