Performance enhancement of carbon/copper composites based on boron doping

The use of carbon/copper (C/Cu) composites as electrical contact materials has developed rapidly owing to their superior mechanical strength, electrical conductivity, and self-lubricity. However, the non-wettability of carbon and copper restricts further improvement in their performance. In this work, a strategy based on copper-boron alloying is proposed, to improve C/Cu interfacial bonding, and Cu-B/sintered-carbon composites were successfully prepared using a gas pressure impregnation technique. The results show that the compressive and flexural strengths of the modified composites increased by 39% and 54%, respectively, and the C/Cu contact angle decreased from 123.6° to 21.3° in the case of 2.5 wt% B doping. A minimum electrical resistivity of 1.7 μΩ·m was achieved when a moderate boron content (1.2 wt%) was selected. The role of boron carbide was examined, and competitive mechanisms of C/Cu interfacial bonding level and electrical conductivity are proposed, based on aspects of interfacial resistance and scattering of conducting electrons.