Microstructure and Thermal Conductivity of Al-Graphene Composites Fabricated by Powder Metallurgy and Hot Rolling Techniques

The objective of this research is to improve the thermal conductivity and mechanical properties of Al/GNPs (graphene nanoplatelets) nanocomposites produced by classical powder metallurgy and hot rolling techniques. The microstructural evaluation confirmed the uniform dispersion of GNPs at low content and agglomeration at higher contents of GNPs. The structure of graphene was studied before and after the mixing and the Raman spectrum proofs that the wet mixing has a great potential to be used as a dispersion method. There was no significant peak corresponding to the Al4C3 formation in both the differential scanning calorimetry curves and X-ray diffraction patterns. The microstructural observation in both fabrication techniques showed grain refinement as a function of the GNPs content. Moreover, the introduction of the GNPs not only improved the Vickers hardness of the composites but also decreased their density. The thermal conductivity investigations showed that in both the press-sintered and hot-rolled samples, although the thermal conductivity of composites was improved at low GNPs contents, it was negatively affected at high GNPs contents.