Thermal conductivity enhancement and synergistic heat transfer of z-pin reinforced graphite sheet and carbon fiber hybrid composite

Abstract This paper successfully developed a fiber z-pin reinforced graphite sheet (GS) and carbon fiber (CF) hybrid composite laminate. By taking advantages of the superior thermal conductivities of graphite sheet and z-pins, three-dimensional highly conductive paths were constructed to achieve the multifunctions of advanced polymer composites. The effects of ply scheme and z-pin type on the thermal conductivity and heat transfer process of z-pin reinforced GS/CF composites were investigated to reveal the interfacial heat exchange between z-pin and laminas. The results show that both through-thickness and in-plane thermal conductivities are enhanced significantly by implanting through-thickness z-pins in GS/CF composites. This is ascribed to the effective through-thickness conductive paths of z-pins and the synergistic heat transfer of graphite ply and carbon fiber pins. For [GS/CF4/GS]-PAN-pin composite, about 15% laser flash energy transfers through z-pins with a volume fraction of only 2.18%. More obvious heat exchange between z-pins and lamina may be achieved by implanting pitch-based carbon fiber z-pins with higher thermal conductivity and smaller diameter. The resultant through-thickness and in-plane thermal conductivities of [GS/CF4/GS]-pitch-1-pin are measured to be 8.80 W·m−1K−1 and 18.50 W·m−1K−1, which are 13.7 and 8.3 times higher than those of control sample, respectively.