Study On Wear Resistance And Corrosion Resistance Of Tungsten Carbide And Chromium Carbide Coating

In surface engineering and mechanical engineering,cemented carbide coatings have the characteristics of corrosion resistance and wear resistance,so the application of cemented carbide coatings has received widespread attention.This thesis takes the ball valve of Wu zhong Instrument.as the research object.The ball valve body is one of the important components of the ball valve.In actual application,the ball valve body is subject to the dual effects of corrosion and wear.Using supersonic flame spraying technology(HVOF)to prepare WC-Co,NiCr-Cr3C2 cemented carbide coating on 304 stainless steel substrate and use it with HVT-1000 image processing micro hardness tester,XDR(X-ray diffractometer),Scanning electron microscope(SEM)related testing instruments test the surface hardness and internal microstructure of WC-Co and NiCr-Cr3C2 cemented carbide coatings;use electrochemical instruments to detect and analyze WC-Co and NiCr-Cr3C2 hard Corrosion resistance of alloy coatings at different temperatures,different concentrations of H2SO4 solutions,and different corrosion media(3.5%NaCl solution,0.1mol/L NaOH solution,0.1mol/L H2SO4 solution,0.1mol/L HNO3 solution),last used The friction and wear tester tests the wear resistance of WC-Co and NiCr-Cr3C2 cemented carbide coatings.The results of experimental testing and analysis show that.The hardness value of WC-Co cemented carbide coating is between 1100?1400HV0.2,the hardness value of NiCr-Cr3C2 cemented carbide coating is 960HV0.2,and the hardness value of WC-Co cemented carbide coating is obviously greater than NiCr-Cr3C2 hard alloy coating.The XRD test showed that the WC-Co and NiCr-Cr3C2 cemented carbide coatings were produced in W2C,Cr7C3 and Cr23C6 phases and the two types of cemented carbide coatings successively decarburized.The results of SEM experiments show that the WC-Co and NiCr-Cr3C2 cemented carbide coatings have hard phases and bonding phases composed of different elements and the hard phases and the bonding phases are staggered.In 0.5mol/L H2SO4 solution,the temperature values are adjusted to 25?,45?,60?,respectively.The corrosion potential of WC-10Co4Cr in WC-Co is positive potential and the corrosion rate is the smallest,the corrosion rate is 0.049(g/m2 h),0.158(g/m2h),0.277(g/m2h),the corrosion potential of NiCr-Cr3C2 cemented carbide coating is negative and the corrosion rate is the largest,the corrosion rate is 0.277(g/m2h),1.400(g/m2h),6.126(g/m2h).The corrosion rate of WC-Co and NiCr-Cr3C2 cemented carbide coatings increases correspondingly with increasing temperature.Using 1%,3%,5%,and 10%H2SO4 solutions,the corrosion potential of WC-Co,NiC-Cr3C2 cemented carbide coatings includes positive and negative potentials?and WC-Co cemented carbide coatings The corrosion rate increases with the increase of the concentration of the corrosion solution,and the corrosion rate of the NiCr-Cr3C2 cemented carbide coating shows a trend of decreasing first and then increasing with the increase of the solubility of the corrosion solution.Corrosion media are 3.5%NaCl,0.1mol/L NaOH solution,0.1mol/L H2SO4 solution,0.1mol/L HNO3 solution,and the corrosion potential of WC-Co,NiCr-Cr3C2 cemented carbide coating is negative potential,the corrosion rate of the two types of cemented carbide coatings in different corrosion media is different,the minimum corrosion rate of WC-10Co4Cr in 3.5%NaCl solution is 0.014(g/m2h);0.1mol/L NaOH The minimum corrosion rate of WC-12Co in solution is 0.028(g/m2h);the minimum corrosion rate of WC-10Co4Cr in 0.1 mol/L H2SO4 solution and 0.1 mol/L HNO3 solution is 0.035(g/m2h),0.052(g/m2h).The experimental conditions for friction,wear,and friction are additional load of 50N,movement frequency of 5Hz,and friction time of 30min.Under the same experimental conditions,the friction coefficients of the WC-Co and NiCr-Cr3C2 cemented carbide coatings are 0.543,0.539,0.484,and 0.477,respectively,the wear losses are 0.0052g,0.00203g,0.00173g and 0.0009g,respectively.The wear resistance of Co-based cemented carbide coating is greater than that of NiCr-Cr3C2 cemented carbide coating.From the analysis of the wear mechanism,it can be seen that the WC-Co cemented carbide coating is mainly abrasive wear,and the NiCr-Cr3C2 cemented carbide coating has two aspects of adhesive wear and abrasive wear.