Influence Of Duty Ratio Of Bias On Structure And Properties Of Nitride Coatings Deposited By Arc Ion Plating

Transtent subgroup metal nitride coatings such as TiN coatings, CrN coatings and ZrNcoatings have been widely used in the modification of cutting tools due to their excellentproperties including high melting point, high microhardness, high thermal stability,corrosion-resistance and oxidation-resistance.This kind of nitride coatings have poor hightemperature resistance because of the columnar structure. The composite coatings such asTiAlN coatings and TiCrN coatings have higher red hardness and higher thermal stability.The process of Pulse bias arc ion plating has the advantages of high interface bondingstrength, low substrate temperature and low residual stress. In this paper, the TiN coatings,CrN coatings, ZrN coatings and TiAlN coatings were doposited by pulse bias cathodic arcion plating process. The effect of various duty ratio（10%,30%,50%,70%,100%） on thebasic characteristics of these coatings such as the surface morphology, the microstruture,the mechanical and tribological properties were investigated. The study results show asfollowing:（1） The number of the surface pit and macroparticles on the surface of TiN coatingsfirst decreases and then increases with the increase of the duty ratio. The highestmicrohardness, the lowest surface roughness and wear rate were achived from the coatedsample with the70%duty ratio. The microhardness first increases and then decreases withthe increase of the duty ratio. Under the unlubricated conditions, the duty ratio has littleeffect on the friction coefficient of the TiN coatings.（2） The number of the surface pit and macroparticles on the surface of CrN coatingsfirst decreases and then increases with the increase of the duty ratio. The microhardnessfirst increases and then decreases with the increase of the duty ratio. The sample with70%duty ratio has the lowest surface roughness, and the sample with30%has highestmicrohardness. The phase composition of the CrN coatings is CrN and Cr₂N. Under theunlubricated conditions, the sample with70%duty ratio has the lowest friction coefficient,and the lowest wear rate was achived from the sample with30%duty ratio.（3） The number of the surface pit and macroparticles on the surface of ZrN coatingsfirst decreases and then increases with the increase of the duty ratio. The microhardness first increases and then decreases with the increase of the duty ratio.The sample with50%duty ratio has the lowest surface roughness. The diffraction peaks of ZrN coatings cotainZrN（111）, ZrN（200）, ZrN（311）. The sample with70%duty ratio has the highestmicrohardness. Under the unlubricated conditions, the sample with50%duty ratio has thelowest friction coefficient, and the lowest wear rate was achived from the sample with70%duty ratio.（4） The number of the surface pit and macroparticles on the surface of TiAlN coatingsfirst decreases and then increases with the increase of the duty ratio. The microhardnessfirst increases and then decreases with the increase of the duty ratio. The sample with70%duty ratio has the lowest surface roughness. The diffraction peaks of TiAlN coatings cotainTi₂N（112）, Ti₂N（200）, Ti₃Al₂N₂（105）, Ti₃Al₂N₂（112）. The sample with50%duty ratio hasthe highest microhardness. Under the unlubricated conditions, the sample with70%dutyratio has the lowest friction coefficient, and the lowest wear rate was achived from thesample with50%duty ratio.