Effect of interfacial structure on the thermal conductivity of carbon nanofibers reinforced aluminum nitride composites

The interface in carbon nanofilaments/ceramic–matrix composites significantly affects the interfacial thermal transfer characteristics. In this work, the effect of interfacial structure on the thermal conductivities of carbon nanofibers (CNFs)/aluminum nitride (AlN) composites with and without sintering aids (Y2O3 and CaF2) were studied. For the composites sintered with aids, the interfacial amorphous glass phases originated from the aids and Al2O3 layer in AlN powders surrounded the CNFs, which acted as elongated pores for deteriorating the thermal conductivity. However, a clean interface was obtained in the composites without aids because the amorphous carbon and the Al2O3 layers in the CNF–AlN system were removed by their interreaction to form volatile products such as Al2O and CO, resulting in the enhanced thermal conductivity. Moreover, theoretical analysis was also employed to investigate the effect of the interfacial structure on the thermal conductivity of the CNFs/AlN composites.