Study On Microstructure And Properties Of CrTiAlN Coatings Deposited By Closed Field Unbalanced Magnetron Sputtering

The rapid development of modern cutting industry leads toincreasing demands for the performance of cutting tools.The surface coating technology,by modifying the surface performance of cutting tools,is an effective way to improve the comprehensive properties of cutting tools.In this paper,CrTiAlN coatings and CrAlN coatings were deposited on M2 HSS substrates by closed filed unbalanced magnetron sputtering ion plating technology.The microstructure,composition and morphology were characterized and analyzed by using XRD,SEM and EDS.The adhesion and microhardness were measured by Rockwell indentation tester and vicker microhardness meter.The tribological properties were evaluated by high temperature tribometer.The oxidation resistance and corrosion resistance of CrTiAlN coatings were also studied.The results are concluded as follows:The surface morphologies of CrTiAlN coatings and CrAlN coatings exhibit tightly packed grains,the cross-sectional morphologies exhibit columnar structure,and the main crystalline phases are CrN,Cr and Cr₂N.Rockwell indentation tests show good adhesion of CrTiAlN coatings and CrAlN coatings.High temperature oxidation resistance tests indicate that CrTiAlN coatings improve the oxidation resistance of M2 HSS substrates markedly,the microstructure of CrTiAlN coatings do not change significantly when the oxidation temperature belows 700℃,but when the oxidation temperature reaches 900℃,the coatings appear Cr₂O₃ phase.This suggests that the coatings have been oxidized.3.5%NaCl solution electrochemical experiments show that CrTiAlN coatings improve the corrosion resistance of M2 HSS substrate dramatically.High temperature friction and wear tests show that the wear resistance increases after CrTiAlN coatings and CrAlN coatings deposited on M2 HSS substrates.From room temperature to 600℃,friction coefficients of the coatings increase first and then decrease.Wear rates increase with the increase of temperature.And the wear rates of CrAlN coatings are always higher than CrTiAlN coatings.The wear forms of coatings are mainly oxidation wear,adhesive wear and abrasive wear.