Synergistic Effects of B4C and Graphite on the Multi Functional Properties of Copper-Based Hybrid Composites

Abstract

In this study, Cu-based composites reinforced with boron carbide (B4C) and hybrid B4C-graphite additions were fabricated via the powder metallurgy (PM) route. The effects of reinforcement content and sintering parameters on the mechanical, electrical, wear, and microstructural properties were systematically investigated. The optimum composition for single phase reinforcement was obtained with 1 wt% B4C, sintered at 850 degrees C for 1 h, showing significant improvements in hardness (similar to 90.4 HV), compressive strength (768 MPa), and wear resistance, while maintaining good electrical conductivity with only a similar to 6.7 % increase in resistivity compared to pure copper. Increasing B4C content to 3-5 wt% resulted in higher porosity, grain coarsening, and Cu2O formation, which deteriorated both strength and conductivity. Hybrid composites produced with 1 wt% B4C and varying graphite additions (3-15 wt%) revealed a balance between lubrication and mechanical properties. The Cu-1B(4)C-3Gr sample exhibited the best performance, with compressive strength of similar to 600 MPa, hardness of similar to 99 HV, low wear rate (8.1 x 10(-5) mm(3)/N center dot m), and relatively stable electrical resistivity. At higher graphite contents, excessive porosity and weak interfaces promoted strength degradation, despite improved lubricating behavior. XRD and SEM-EDX analyses confirmed phase stability of B4C and graphite within the Cu matrix, while localized Cu2O formation was more evident at higher graphite ratios. Overall, the results demonstrate that controlled hybrid reinforcement particularly Cu-1B(4)C-3Gr offers a promising strategy for developing copper-based composites with an optimum balance of mechanical strength, wear resistance, and electrical performance for advanced engineering applications.