Study On The Microstructure And Wear Performance Of WC/Fe Based Composites Under Three-dimensional Prefabricated Structure Design

With the development of modern industry,the demand for mechanical parts that can work well in complex environments in countries around the world is increasing every year.Especially in mining,electric power,building materials and other fields of grinding equipment,its harsh and harsh service environment puts forward higher requirements for the performance of material wear-resistant parts.With the continuous development of technology,a WC/Fe matrix composite composed of ceramic particles and metal matrix has attracted more and more attention from researchers,this ceramic metal composite material can greatly improve the wear resistance of the metal matrix,and the ceramic metal composite material has become a research hotspot for wear-resistant materials.Compared with the traditional whole-layer composite iron-matrix composite,the composite material with three-dimensional precast spatial configuration can better integrate the respective advantages of ceramic particles,composite area and substrate area,and improve the impregnation ability of molten metal through the"build-dissipate"design of three-dimensional structure preform,regulate the distribution and microstructure of elements in the composite,and solve the problems of thin,easy peeling and unstable wear process of ceramic particle Fe-based surface composite composite prepared by liquid metal impregnation.In this paper,WC granularized high chromium cast iron-based（HCCI）composites were prepared by 3D printing and sand casting to construct prefabricates with different three-dimensional structural parameters by 3D printing.The structural parameters of the three-dimensional precast collapse and metallurgical reaction with the molten metal to form the WC composite layer,and the influence of the structural parameters on the dissipation ability of the three-dimensional preform and the microstructure and properties of the composite material are studied by setting the structural parameters of the three-dimensional preform.The microstructure of WC/Fe matrix composites was studied by optical microscopy（OM）,scanning electron microscopy（SEM）,energy spectroscopy（EDS）,X-ray diffraction（XRD）and electron backscattering diffraction（EBSD）,and the influence of different preform structural parameters on the hardness and wear properties of the composites was tested by automatic microhardness tester and wear testing machine.The experimental results show that:1.Under different precast structural parameters,with the impregnation of molten metal,the three-dimensional precast structure diffuses,WC particles and high chromium cast iron dissolve and diffuse to form a tungsten alloyed composite layer,and with the increase of wall thickness,the dissipation capacity of the precast is now increasing and then decreasing trend,and with the increase of the number of precast edges,the dissipation capacity of the precast gradually increases.The microstructure of the composite is mainly WC composite region,metal matrix and WC reinforced particles that are not completely dissolved locally.The WC composite reaction layer is mainly composed of W,Fe and Cr elements,and the matrix region is mainly composed of Cr,Fe and W elements.The composite layer is Fe₆W₆C carbide in network morphology,and the metal matrix is composed of M₇C₃ carbide.Changes in the three-dimensional structure of the precast do not affect the type of composite phase.2.The shape of the precast body is square,and when the wall thickness of the precast body increases from 2.5mm to 10mm,the hardness of the matrix does not change much,the hardness of the composite layer increases first and then decreases,and the hardness of WC particles gradually increases.The stable friction coefficient of the composite material and the grinding loss weight of the three-body abrasive showed a trend of first decreasing and then increasing,indicating that the wear resistance of the material increased first and then decreased.When the friction coefficient reaches a stable state,the minimum friction coefficient is 0.54 when the wall thickness of the precast body is 7.5mm,the average wear loss weight of the three-body abrasive is 0.2328g,and the wear resistance is 4.2960,which is 21.9%higher than 2.5mm.When the wall thickness of the precast is 7.5mm,the metallurgical combination between the matrix and the WC reinforced particles is good,the proportion of tungsten alloyed composite layer formed by the dissipation of the precast is the highest,and the hardness and wear resistance of the composite material are the best.3.When the wall thickness of the precast body is 7.5mm,the aperture wall thickness ratio of the precast body is 1,and the shape parameters of the precast body are triangular,quadrilateral and hexagonal,with the change of the shape of the preform,the hardness of the matrix gradually increases,the hardness of the composite layer increases first and then decreases,and the hardness of WC particles is about2200 HV.When the shape of the precast body is hexagonal,the maximum hardness of the matrix is 921.7HV,the hardness of the composite layer is 1450.4HV,and the hardness of the composite layer is the quad,which reaches 1618.6 HV.The stable friction coefficient of the composite material and the grinding loss weight of the three-body abrasive showed a gradual decrease trend,indicating that the wear resistance of the material gradually increased.When the friction coefficient reaches a stable state,the stable friction coefficient of hexagonal preform is the minimum of0.51,the average wear loss weight of three-body abrasive is 0.2108g,and the wear resistance is 4.7438,which is 11.8%higher than that of the triangle,indicating that its wear resistance is the best.