Evolution of the microstructure, electrical, and tribological properties of copper-based composites reinforced with MoB₂ ceramic particles

Copper materials have been widely used in electronic and electrical engineering fields due to their desirable electrical and thermal conductivity, superior fatigue resistance, and high softening temperature. However, the inherent incompatibility between electrical conductivity and wear resistance cannot be avoided. Boride ceramic particles may balance the tribological and electrical properties of the composites. MoB₂/Cu composites with varying boride content were fabricated using ball milling and spark plasma sintering. MoB₂ ceramic particles were dispersed in the Cu matrix, exhibiting good interfacial bonding; however, cracks and debonding appeared around the MoB₂ particles when excess boride content was involved. As MoB₂ content increased, the microhardness of the MoB₂/Cu composites improved significantly from 128.42 HV to 190.70 HV, while the electrical conductivity decreased from 52.10 %IACS to 17.34 %IACS. The wear resistance of the composites initially increased and then decreased as the boride content increased. Therefore, the wear resistance of the composite with 20 wt% MoB₂ was 12.308 times higher than that of the composite with 5 wt% MoB₂. The wear mechanism of composites shifted from two-body cutting wear to three-body abrasive wear, accompanied by oxidation and lubrication.