Microstructures And Properties Of WC Particle Reinforced Fe-based Wear-resistant Cladding Coating

Particle reinforced metal matrix composite materials plays an important role in improving the performance of materials and prolonging the service life of parts.Especially,it can improve the wear resistance of the composites by adding ceramic particles into metal matrix.It is a hotspot in the field of wear resistant materials research.Due to the advantages of high efficiency,low cost and good quality of cladding,plasma cladding technology is widely used in industrial production.At present,WC particle reinforced iron based cladding layer has gotten some achievements.But the distribution of WC particles and powder of the low utilization rate has not been solved.So this dissertation attempts to improve the process conditions of WC particles and Fe based alloy composite case.In this dissertation,a developed plasma cladding back powder feeding technology is used for the preparation of WC particles on the surface of 45# steel reinforced Fe based wear resistant cladding which is without crack,forming good porosity.This dissertation studies the effect of the improved technology,back powder feeding voltage,WC particles on the Fe based cladding layer.The microstructure and wear resistance of the cladding layer and the effect of heattreatment on the microstructure and properties of the cladding layer were studied.OM,SEM,EDS and XRD were used to analyze the microstructure and the composition of the cladding layer,and the wear resistance of the cladding layer was analyzed by using a self-made friction tester.The results show that the use of back powder feeding technology improvement can make WC particles in the cladding of uniform distribution and the powder utilization rate increased significantly,while WC particles retained around WC particles dissolved only 4⁵?m.The main phase of the cladding layer is composed of WC,W₂C,?-Fe,Cr₂₃C₆,Fe₃W₃C,Cr₃C₂ and Cr₇C₃.When the powder feeding voltage is 8V,WC particles is deposited at the bottom of the cladding layer.When the powder feeding voltage is above 10 V,and WC particles is evenly distributed in the cladding layer.The hardness of the cladding layer was significantly higher than that of the substrate,and the highest Vickers hardness reached 1600 HV10.Compared with spherical casting WC and polygonal crystal WC,the former powder flow ability is better,and the utilization ratio of WC is higher.The cladding layer is quenched at 1100? and tempered at different temperatures.Through the analysis of the phase,the species did not change much and there are differences in the content of phase.After heat treatment,the relative content of Cr₂₃C₆ decreased and Cr₇C₃ increased.There are a large number of white carbide particles precipitated in the tempering zone at 550 ?,and the dispersion of the particles is less than that of the white particles in the process of tempering at 200 ? and 650 ?.The orthogonal experiment shows that the quenching temperature is between 900¹100 ?,and the higher the temperature is,the more the granular carbides will be precipitated.The wear mechanism of WC particle reinforced Fe based wear resistant coating was mainly abrasive wear,and the wear resistance of the cladding layer was significantly improved compared with that of Cr12 Mo V.