The Research On Microstructure And Properties Of High Vanadium Fe-based Coating By Plasma Surfacing

Wear-resistant materials are widely used.Wear and corrosion are unavoidable in the use of wear-resistant materials.The economic losses caused by wear and corrosion in China are hundreds of billions of yuan every year.Compared with single casting method,surface engineering technology can reduce material consumption,save cost,prolong the service life of equipment or overhaul cycle,and has higher economic benefits.As one of the surface engineering technologies,plasma surfacing is widely used in manufacturing and material repairing because of its low cost,high efficiency of coating preparation and easy automation.However,there are few studies on plasma technology and modification of high vanadium Fe-based coating.This topic use high vanadium Fe-based alloy powder WC powder as raw materials to prepare high vanadium Fe-based surfacing coating and high vanadium Fe-based alloy coating doped WC powder by plasma surfacing method.By single factor an,orthogonal test method and using X-ray diffraction?XRD?,Scanning electron microscopy?SEM?,Electronic energy spectrum?EDS?,Optical microscopes?OM?,hardness meter,wear tester and other analytical and testing means to study effects of process parameters of plasma surfacing welding?Surfacing current,powder feeding rate,surfacing rate?,WC powder doping quantity,morphology and granularity on phase composition,microstructure,hardness and wear resistance of high vanadium Fe-based surfacing coating.The results show that,the better process parameters surfacing current is 160A,powder feeding Rate is 30g?min^-1,surfacing rate is 150mm?min^-1,the wear volume of coating is0.062g;Process parameters of plasma surfacing welding?Surfacing current,powder feeding rate,surfacing rate?have a great influence on the microstructure and properties of surfacing coating,effect of surfacing process parameters on the composition of the coating is small.The main crystalline phase of surfacing coating is?-Fe,VC,M₇C₃ type eutectic carbide,small spherical VC particles with dispersive sidtribution in Fe matrix and?Fe,Cr,V?₇C₃eutectic carbide form a wear-resistant skeleton of the coating to improve wear resistance of surfacing coating;Abrasive wear and adhesive wear are the main wear resistance coating on high vanadium iron base.The presence of VC particles can obviously prevent the spread of wear scratches and improve the wear resistance of surfacing coating.The addition of WC powder in high vanadium Fe-based alloy powder has a great influence on the structure and properties of high vanadium Fe-based surfacing coating,which is conducive to improve the wear resistance of the coating.The morphology of WC powder doped has a great influence on the structure and properties of surfacing coating.The diffusion degree of WC particles with different morphologies is obviously different.Irregular WC powder doped will generate many needle-like carbides in the surfacing coating,which can effectively enhance the wear resistance of the coating.The strength of the bonding between WC particles and coating matrix is relatively poor when doped with spherical WC,and the strengthening of surfacing coating is limited.The wear resistance of surfacing coating doped with irregular WC powder is better than that doped with spherical WC powder.The content of WC powder has a great influence on the structure and properties of surfacing coating,the optimum content of WC powder is 30wt.%.The particle size of doped WC powder influences the properties of surfacing coating.Ultrafine WC powder dissolved in surfacing coating at high temperature is beneficial to improve the strength and wear resistance of surfacing coating matrix,but when the content of WC powder is higher??10wt.%?,it is easy to make the pipeline blocked and its application in plasma surfacing is limited.When WC powder is added into high vanadium Fe-based alloy powder,the reactions between Fe,Cr,V and WC occur during surfacing.The main phases of surfacing coating are Fe,M₇C₃,VC,V₂C,WC,W₂C,M₆C and M₃C carbides.The wear mechanism of surfacing coating doped with WC particles is mainly abrasive wear and adhesive wear.WC particles and VC particles bear wear together,which can effectively resist the spread of scratches and improve the wear resistance of coating.