Thermal conductivity enhancement and heat transport mechanism of carbon fiber z-pin graphite composite structures

Abstract This paper successfully constructed an innovative carbon fiber z-pin graphite composite with three-dimensional thermal conductive paths by taking advantages of high conductivities of both graphite sheet and z-pin. The effects of structural parameters and temperature on thermal conductivity (TC) were investigated, and thermal transport mechanism was analyzed. The results show that pyrolytic graphite sheet (PGS) and expanded graphite sheet (EGS) composites both show considerable increase in through-thickness TCs reaching up to 1.80–6.20 W m −1 K −1 after implanting carbon fiber z-pins. Infrared thermography demonstrates the formation of three-dimensional heat conductive paths in-between graphite sheet and z-pin. Our results indicate that the synergistic effect of the heat exchange becomes more evident with the increase in the in-plane TC of graphite sheet and particularly the axial TC of z-pin. The maximum through-thickness TC of 6.20 W m −1 K −1 is achieved, which is 647% higher than the control sample.