Study On The Structures And Performance Of Cr（N/C）-WC/Cr₃C₂ Composite Coating

At present,to improve the comprehensive use of ball valves and service life has become a research hot spot in the field of valve.The surface modification technology is one of the most widely used so lut ions.C r（N/C）-WC/C r₃C₂ Composite coating was prepared on the sealing surface of ball valve with supersonic fla me spraying technology（HVO F）and Mult i arc ion Plating（PVD）technology.The experimental results show that Cr（N/C）-WC/Cr₃C₂ composite coating can effectively improve the wear resistance and corrosion resistance of the ball valve sealing surface,and improve the comprehensive performance and service life of the ball valve.WC/C r₃C₂ Coating and C r（N/C）-WC/Cr₃C₂ composite coating were prepared on 316stainless steel surface by the combination of supersonic flame spraying technology（HVO F）and mult iple arc ion plating（PVD）.The microstructure and image composition of the composite coating were studied by SEM、EDS and XRD,and the surface hardness of the composite coating was tested by means of the micro-hardness tester,and the material surface synthesis tester and electrochemical workstation were used.The friction and wear properties and electrochemical corrosion properties of composite coatings w ere tested and analyzed,and the results were as follows;（1）The WC and C r₃C₂ coating prepared by supersonic flame spraying technology and coated spraying powder have low porosity,good compactness and high hardness.By XRD analysis,it is found that WC coating mainly contains WC phase and a small amount of C o₃W₃C phase and Co₆W₆C phase,Cr₃C₂ coating mainly has Cr₃C₂ phase,Cr₇C₃ phase and N iC r phase.In the low load,the wear of WC and Cr₃C₂ coating is mainly abrasive wear,with a small amount of adhesion wear,the wear forms of Cr₃C₂coating under high load are mainly fatigue wear and abrasive wear,and the wear form of WC coating is mainly abrasive wear and adhesion wear.（2）The C rN/C rC thin film prepared by multi arc ion plating on WC/Cr₃C₂ coating have compact structure and a small number of droplets and pits on the thin film surface,in which C rN film is superior to C rC film in thickness and compactness.The results of XRD show that the C rN film is mainly composed of C rN phase,C r phase and a small number of C r₂N phases,and C rC film is mainly composed of C r₇C₃ and C r phases.Cr（N,C）-WC/C r₃C₂ composite coating compared to WC/Cr₃C₂ coating has higher hardness,its hardness is up to 2000HV above,at least 70%increase.（3）The Wear forms of C r（N/C）-WC/C r₃C₂ composite coating under low load are mainly abrasive wear,and the wear forms of C r（N/C）-WC/Cr₃C₂ composite coating under high load are mainly fatigue wear.The C rN and C rC film has good abrasion resistance,its existence effectively suppresses the adhes ion wear and abrasive wear of WC and Cr₃C₂ coating.Compared with single WC/C r₃C₂ coating,C r（N/C）-WC/Cr₃C₂composite coating has better wear resistance,in which the wear resistance of CrN-WC/C r₃C₂ composite coating is superior to that of CrC-WC/C r₃C₂ composite coating.（4）The presence of C rN/Cr C film prevents corrosive media from entering the coating through the pores and pores of the WC/C r₃C₂ coating,and the CrN/C rC film excellent corrosion resistance,so in the volume fraction of 10%H₂SO₄ solut ion,The corrosion resistance of C r（N/C）-WC/Cr₃C₂ composite coating was significantly improved compared with that of single WC and C r₃C₂ coating.The corrosion resistance of CrC-Cr₃C₂、CrN-C r₃C₂、CrN-WC and CrC-WC composite coatings decreased gradually.