Microstructure and Tribological Performance of Cu Matrix Composites Reinforced with Cu-modified WC Particles
Tungsten carbide(WC)particle-reinforced composites are widely used owing to their excellent mechanical properties.The limited solubility of WC in Cu and the weak mechanical interface between the WC particles and the Cu matrix are the main factors contributing to the suboptimal tribological performance of these composites.To address this issue,the surface modification of WC particles is crucial for optimizing the interface and enhancing the bonding strength between the particles and the matrix.In this study,porous spherical WC particles were modified with Cu via spraying and sintering.Cu matrix composites reinforced with five different amounts of Cu-modified WC particles(0 and 5 wt.％,10 wt.％,15 wt.％,20 wt.％,and 25 wt.％)were prepared using a powder metallurgy technique.The mechanical and tribological properties of the Cu matrix composites were tested using a hardness tester and a UMT3 friction tester.Nanoindentation and scanning electron microscope(SEM)line scanning were used to characterize the interface of the Cu-mdified WC particles and Cu matrix.Macro-and microstructural characterization and tribological performance analysis were performed on Cu matrix composites reinforced with Cu-modified WC particles.The results of this study indicate that the Cu-modified WC particles were effectively embedded in the Cu matrix,resulting in the formation of a submicron diffusion layer at the interface between the modified particles and the matrix.This modification process led to a 33％increase in elastic resilience and a 20％increase in hardness at the interface.Microcracks within the particles as well as between the particles and Cu matrix contribute to an increase in porosity.Among the tested composites,the Cu-matrix composite reinforced with 15 wt.％Cu-modified WC particles exhibited superior tribological performance.The friction coefficients of this composite showed minimal fluctuations,stabilizing at approximately 0.75,with wear volumes decreasing to 0.075 mm3.The worn surfaces of 15 wt.％Cu-modified WC reinforced composite displayed fairly smooth contours,the shallowest grinding crack,and large-scale continuous films.Furthermore,as the Cu-modified WC content increased,the main wear mechanism shifted from adhesive to abrasive wear at 15 wt.％,and eventually to fatigue wear at 25 wt.％.The surface friction transfer layers of the composites were characterized by the presence of Cu,Fe,O,and W.The Fe from the sliding friction pairs and absorbed oxygen contributed to the formation of a tribological film.Additionally,the presence of the modified particles causes deflection in the direction of the cracks and reduces their expansion at the corresponding locations.This research demonstrates a significant improvement in the interfacial bonding strength between the Cu-modified WC particles and Cu matrix.A composite material with 15 wt.％Cu-modified WC effectively inhibits adhesion wear and fatigue wear,resulting in excellent tribological properties.The utilization of Cu-modified WC particles to reinforce Cu-matrix composites offers a promising approach for optimizing the interface between WC and the Cu matrix,thereby enhancing the tribological properties of Cu-matrix composites.This paper has significant implications for the practical application of Cu-modified WC particles in Cu-matrix composites and provides a theoretical foundation for further research in this area.
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