Preparation And Properties Of CrN Based Coatings Deposited By Plasma-Enhanced Magnetron Sputtering

CrN coating has advanced mechanical and wear-resisting properties,such as high hardness,strong bonding strength and low wear coefficient.With the service environment of workpiece becoming more and more severe,the CrN coating has failed to fulfill the work requirements.The way contributing to success of the solving problem is adding other elements to traditional binary to form the multilayer coatings,which caused the comprehensive service performance of the coatings improved significantly.In this work,CrSiN and CrAlN coatings were deposited by plasma enhanced magnetron sputtering,the effects of substrate negative bias and doping amount on hardness,bonding strength,wear resistance and high temperature oxidation resistance of the coatings were investigated.The achieved results are as follows:(1)As the negative bias of the matrix increased,CrSiN and CrAlN coatings presented obvious preferred orientation of CrN(111)plane.The hardness,Young's modulus,bonding strength increased first and then decreased with the increase of bias voltage,and the mechanical properties displayed the best performance at-50 V,where the average friction coefficient of the coatings was the lowest and wear resistance was optimal.(2)With the increase of Si contents,the preferred orientation of CrSiN coatings presented variation tendency from CrN(111)crystal face to(200)plane,the hardness,Young's modulus and bonding strength of the coatings increased first.All of them reached maximum values when Si content was 18.5%.The mechanical properties of the coatings reduced distinctly when Si content increased further.The freferred orientation of the CrAlN coatings with different Al content changed from(111)plane to(200)plane,the hardness,bonding force enhanced with the increased Al content first,and then decreased when the Al content increased further.The mechanical properties of the CrAlN coatings presented optimal performance when Al content was 37.8%.(3)With Si content increased,the surface roughness decreased and the average friction coefficient reduced,the wear resistance of the coatings exhibited best performance when Si was 18.5%.With Si content increased further,the roughness,hardness and wear resistance decreased.The average friction coefficient of CrAlN coatings reduced first with increased Al content.The wear resistance displayed the best performance with the smoothest surface when Al content was 37.8%.When Al content enhanced further,the roughness increased and the wear resistance decreased with the defects in the coatings.(4)In this work,the CrSiN,CrAlN coatings with various bias voltage and doping content were deposited on the high temperature alloy surface,and the high temperature oxidation resistance of the coatings under 800? was investigated to determine the optimal parameters.And the best serving temperature and service time of the coatings prepared by the optimal parameters were studied.The experimental results showed that the CrSiN coating displayed the best thermal stability when Si content and bias voltage were 18.5% and-50 V,respectively.Obvious cracks appeared on the coatings surface after oxidation 10 h at 800?,and the oxygen quantity diffused for the substrate surface was enhanced.While the coatings didn't fall off,it still provided protection to a certain extent.When Al content and bias voltage were 51.5%,-50 V,respectively,the high temperature oxidation resistance of CrAlN coatings was optimal.Distinct cracks exhibited on the coating surface,while they didn't extend to the substrate and the oxygen diffusion was relatively slow.The coatings still displayed excellent protection to matrix.