Investigation Of The Properties Of AlCrSiN Coatings Deposited By Arc Ion Plating

High-speed cutting is an efficient,environment-friendly advanced cutting technology.It is currently the development direction of machining,imposing severe requirements on cutting tools.AlCrN coating,owing to high hardness,good wear resistance,excellent thermal stability and oxidation resistance,is an ideal coating material for improving cutting performance of cutting tools and satisfying high-speed cutting.Arc ion plating is one of the main technologies for the preparation of nitride tool coatings in industry.High ionization rates,high particle energies and other characteristics make arc ion plating coatings have good compactness and adhesion,which takes advantages in preparing high-quality tool coatings with high efficiency.In this paper,the AlCrSiN coating was deposited on a cemented carbide and Si substrate by arc ion plating.The effects of arc ion plating process parameters?arc current,bias voltage and magnetic coil voltage?on the coating was investigated.Based on the best process,the thermal stability and oxidation resistance of AlCrSiN coatings were investigated.The surface morphology and cross section structure of the coatings were characterized by scanning electron microscope.The phase of the coating were analyzed by X-ray diffraction.The mechanical properties were investigated by micro-vickers tester and scratch tester.The tribological properties were evaluated by ball-on-disk rotating friction and wear tester.The main findings of the paper are as follows:?1?There are many droplets on the surface of arc ion plating AlCrSiN coating,and there is no obvious columnar structure in the cross section.The main phase of the AlCrSi N coating deposited by arc ion plating is?Cr,Al?N,which has a B1-Na Cl crystal structure.The Si atoms are dissolved in the AlCrN crystal lattice or form amorphous compounds,leading to glassy and featureless cross morphology of coatings.The composition of the AlCrSi N coating deposited by arc ion plating was segregated.Compared with the target composition,the content of Al in the coating decreased,and the Cr increased.?2?The bias voltage and arc current had more significant effect on the hardness and adhesion of AlCrSiN coatings.In the range of 0.5².0 Pa,the effect of N₂ pressure on mechanical properties was relatively small,and the optimal processing parameters of N₂pressure was 2.0 Pa.The hardness and adhesion increase with the arc current first and then decrease,acquiring maximum value at 100 A.?3?Appropriately increasing the bias voltage can refine the grain and improve the surface quality and density of the coating,leading to improving the mechanical properties of the coating.The AlCrSiN coating has the highest hardness?3430 HV?and adhesion?76 N?and excellent wear resistance(4.7×10^-77 mm³N^-1m^-1)at a bias voltage of 150 V.?4?With the increment of the magnetic coil voltage,the mechanical properties of the coating were augmented by reducing the number and size of droplets and increment of Al/Cr.When the voltage is 25 V,the coating got the highest hardness and the lowest wear rate.?5?Annealing in Ar at 700⁹00°C,no significant signals of new phase and the microhardness stabilizing within the range of 2600²700 HV indicated the AlCrSiN coating maintains good thermal stability.The adhesion dropped to 67.6⁴7.5 N.At 1000°C,the fcc-?Cr,Al?N phase transformed to hcp-AlN and c-CrN,resulting in a coating hardness of2397 HV.?6?The initial oxidation temperature of AlCrSiN coating is between 800⁹00°C.The coating began to be oxidized to?Cr,Al?₂O₃ at 900°C.The coating failed at 1000°C,the W element diffused from substrate and Cr was oxidized to form a large amount of Cr₂WO₆particles.During the oxidation of AlCrSiN coatings,the surface droplets act as diffusion channels to reduce the oxidation resistance of the coatings.With the increase of temperature,Cr and Al diffuse outward,combining with O to form a dense oxide layer,which can hinder O diffusing inward.Simultaneously,Si promotes the formation of a dense structure and the oxidelayer mixed with SiO_2,Al₂O₃ and Cr₂O₃ can hinder the elemental interdiffusion.A variety of effects ensure the excellent oxidation resistance of AlCrSiN coatings.