Preparation And Properties Analysis Of The WC Reinforced Fe-base Coating Prepared By Plasma Spray Welding

WC has high melting point,high hardness,stable performance and good resistance to wear resistance.The application of WC as a fortified phase in the preparation of metal based coatings has a wide range of applications in cutting tools,refractories,wear-resistant components and aerospace and other fields.Because plasma cladding technology has the excellent surface strengthening effect,simple operation and low processing cost,it has been mature gradually after years.Preparating the ceramic reinforced metal matrix composite coatings on steel surface by plasma claddingcan greatly improve the surface wear resistance of steel,prolong the service life of materials,and save materials and production costs.In this paper,the WC reinforced iron based composite coatings with WC in the content of 15%,30%,45%and 55%were prepared by plasma cladding under suitable technological parameters.The effect of WC content on the microstructure and properties of iron based composite coatings was investigated.Then the tungsten carbide(WC)-reinforced Fe-based composite coatings with different contentof Yttrium oxide(Y2O3)were prepared by plasma cladding.The contents of Y2O3 were 0.6%,1.5%,2.5%and 3.5%,respectively.The microstructure,phase structure and microstructure characteristics of plasma cladding layer were studied by electron probe,scanning electron microscope and XRD ray diffractometer etc.The hardness of the plasma cladding layer was tested by microhardness tester,and the sliding wear test of the coating surface was carried out by the multi-function friction and wear tester.The main research results are as follows:(1)The cladding layer has a good metallurgical bonding with the matrix material.The cladding layer is well combined with the matrix,the microstructure is uniform and the formability is very good.With the increase of WC content,the strengthening phase in the coating changed from lump to cross flower shape.In the fusion zone of the coating,a plane crystal band with a width of about 4um is found.The grain shows a tendency to grow in plane,cell and dendrite.(2)In the process of cladding,there are a lot of WC dissolution.The main phase in the coating is martensitic phase,?-(Fe-Cr),WC and Cr23C6.When the WC content is 45%,the Fe3W3C appears in the coating.On the one hand,the Fe3W3Cprecipitated around the unmelted WC or primary WC particles,on the other hand,it can form nucleation independently,and the content ofFe3W3C is increased in the coating with WC content of 55%.(3)With the increase of WC content,the hardness of the cladding layer is obviously increased,and when the content of WC is 55%,the average hardness of the cladding layer is the highest,and the average hardness reaches 1165HV.With the increase of WC content,the friction coefficient of the coating is increased.When the content of WC is 55%,the wear resistance of the WC-Fe composite coating is the best(4)The decomposition of Y2O3 occurred during the cladding process and the element Y is mainly distributed at the boundaries of WC particles and the grain boundaries in the form of Fe17Y2.With the increase of the content of Y2O3 in the coating,the WC in the coating showed a sunflower like,a small block,a radial stamen and cross.(5)The addition of the proper amount of Y2O3 can refine the size of WC particles and the grains in the coating.When the content of Y2O3 is 1.5%,the size of WC particles is the smallest,and the addition of excess Y2O3 will increase the size of WC and grain in the coating The addition of appropriate amount of Y2O3 can reduce the wear volume and improve the wear performance of the coating.When the content of Y2O3 is 0.6%,the wear volume of the coating is the smallest.With the increase of Y2O3 content,the wear volume of the coating is increased.