Study On Wear Resistance Of Multi-Scale Particle Reinforced Iron Matrix Composite Layer By Laser Melt Injection

Friction and wear phenomena are common in industrial production and daily life.The economic loss caused by wear accounts for about 30%⁵0%of the overall energy consumption.The wear resistance of composites can be improved obviously by preparing the composite material layer on the surface of the metal matrix.The wear resistance layer is of great significance in improving the service life of the product,saving energy and reducing cost.In this study,micro-,nano-and multi-scale WC/Fe particle reinforced metal matrix composite layers were prepared on the surface of 4Cr5MoSiV1 hot-working die steel by laser melt injection technology.The influence law of process parameters on the morphology of composite layers was studied,and the microstructural characteristics of WC/Fe composite layer with different particle sizes were analyzed.Based on the study of wear properties of the composite layer,the microscopic wear mechanism of WC/Fe composites with different particle sizes was expounded.The optimal process window of laser melting injection was obtained by systematic process experiments.The phase composition and microstructure of WC/Fe composites with different particle sizes were analyzed by OM,SEM,and XRD.The WC/Fe composite layers with different particle sizes were all composed of?-Fe,WC,M₂C,and M₆C phases.M₆C exists in the form of WC particle reaction layer,irregular rod,dendritic primary crystal and fishbone-like,thin strip eutectic structure in the matrix.Hardness and wear properties of WC/Fe matrix composite layers with different particle sizes were tested.The results show that the hardness of the composite layer can reach 1003.4HV_1.0,which is 5.4 times that of the matrix.Under the condition of 30N load abrasion,the friction coefficients of multi-scale?WC+WC-10Ni?/Fe composite layers are between 0.40and 0.58,while those of micro-WC/Fe and nano-WC-10Ni/Fe composite layers are 0.62and 0.59,respectively.The friction coefficients of multi-scale composite layers are significantly smaller than those of single-scale ones.When the mass fraction ratio of WC and WC-10Ni is 1:1,the friction coefficient of the composite layer is the minimum,reaching the optimal anti-friction performance.The weight loss of the matrix is 3,3.75,7.5,3.75 and5 times respectively of the composite layers,and the composite layers show excellent wear resistance.When the mass fraction ratio of WC and WC-10Ni is 1:1,the composite layer has the best wear resistance.The wear mechanisms of the matrix and WC/Fe composite layers with different particle sizes under the plane wear were analyzed.Adhesive wear,abrasive wear and oxidative wear occur in both matrix and composite layers during wear process,in which the matrix is mainly subject to adhesive wear,while the WC/Fe composite layers with different particle sizes are dominated by abrasive wear.Carbides such as M₂C and M₆C are pinned to reinforce the matrix in the composite layers,WC particles in the micro-WC/Fe composite layer act as the skeleton and play a role of"shadow effect",WC-10Ni particles in the nano-WC-10Ni/Fe composite layer are dispersed to strengthen the matrix,while the multi-scale?WC+WC-10Ni?/Fe composite layers combine the"shadow effect"of micron WC and the dispersion strengthening effect of nano-WC-10Ni particles.