Influence of CrB₂ micro/nanoparticles on the microstructural characteristics, mechanical performances, and lubrication mechanisms of Cu matrix composites

To keep pace with the rapid development of advanced tribological engineering, boride particles have been used as the reinforcement phase to enhance wear resistance properties while maintaining high electrical conductivity in copper matrix composites (CMC_s). The copper matrix composites reinforced with different CrB₂ contents (CrB₂/Cu) were fabricated utilizing spark plasma sintering. The boride distribution and interfacial bonding of composites were characterized. Moreover, microhardness, electrical conductivity, compressive property, and tribological performance were also measured. As the CrB₂ percentage rises, the composites' microhardness improves to 206.64 HV from 148.32 HV, while the electrical conductivity decreases to 25.05 %IACS. Therefore, the Cu-15wt%CrB₂ composite obtains an optimal combination of electrical and mechanical performances. Meanwhile, the composites' wear resistance initially enhances and then deteriorates with increasing CrB₂ content. Additionally, the Cu-30wt%CrB₂ sample has desirable wear resistance based on the hybrid effect of micro and nanoparticles. However, the inferior compressive strength limits the durability of the Cu-30wt%CrB₂ sample. The composites' failure modes involve oxidation, self-lubrication, and abrasive wear.