On the thermal conductivity of spark plasma sintered alumina hybrid nanocomposites: Estimation modeling and experimental validation

In the current work, an improved model to estimate the thermal conductivity of spark plasma sintered nanocomposites is presented. In the developed model, the thermal conductivity of the matrix was modeled as a function of the average matrix crystallite size rather than taking a constant matrix thermal conductivity. The model has been validated against experimentally measured thermal conductivity of Al₂O₃-SiC-CNT hybrid nanocomposites. Using the experimental and modeling results, it was shown that the addition of SiC and CNT inclusions to alumina resulted in a decrease in its thermal conductivity. The main reason for this decrease was found to be the reduction in the thermal conductivity of the alumina matrix itself because of the reduction in the crystallite size. Additional reduction in the composite thermal conductivity was due to the matrix-inclusion interface resistance and porosity. The predicted and measured thermal conductivities were found to be in good agreement.