Microstructural, mechanical and tribological performances of copper foam modified CFRP composite for pantograph strip

A novel pantograph strip of copper mesh modified carbon fiber reinforced polymer (CFRP) composite was fabricated by impregnating copper foam with the resin mixture of carbon fiber and flaky graphite, following by mold hot-pressing technology. Microstructure, mechanical strength, electric conductivity, friction, and wear behaviors of the composite were investigated and analyzed to explore the fracture failure and wear mechanisms. The results show that the composite obtains much lower electric resistance than that of the pure carbon strip used in China's high-speed railway. Adding carbon fiber can improve impact strength and wear resistance considerably, but has little effect on anti-friction performance. The electric resistance and tribological performances are graphite dependent, reduced electric resistance and friction coefficient can be obtained with the increase of flaky graphite from 0 to 15 wt% while negligible changes of impact strength and wear rate are found. However, further increasing the flaky graphite to 20 wt%, the wear rate reveals a dramatic rise. High content of flaky graphite contributes to the formation of thick tribolayer with unconsolidated structure. And the tribolayer is easy to curl and worn off from the wear surface, leading to severe wear of the composite during the current carrying friction tests.