Effect of graphene addition on thermal behavior of 3D printed graphene/AlSi10Mg composite

Abstract

It is possible to exploit graphene's superior mechanical and thermal properties at the bulk level by reinforcing it in the metal matrix via advanced manufacturing processes. In the present study, the influence of graphene reinforcement on the coefficient of thermal expansion (CTE) and thermal conductivity (TC) of 3D printed graphene/AlSi10Mg composite was evaluated in the temperature range of 25 °C to 500 °C. The composite samples were prepared by conducting ball-milling of graphene (0.1 and 0.2 wt%)-AlSi10Mg powder followed by powder bed fusion (PBF) process. Relative densities of the prepared samples were evaluated by Archimedes' method. A relative density of 99.1% was achieved for 0.1 wt% graphene/AlSi10Mg composite and unreinforced samples, whereas 98.4% was obtained for 0.2 wt% graphene/AlSi10Mg composite sample. Uniform dispersion of graphene in the matrix was achieved through micron-scale melt processing during PBF, which was ensured using Raman spectroscopy. X-ray photoelectron spectroscopy results suggested that graphene is not reacting with the matrix even after laser fusion. The atom probe tomography results further demonstrated the stability of graphene in the matrix. Stable graphene platelets inside the AlSi10Mg matrix were responsible for ~10% reduction in the CTE of the composite owing to the negative CTE of graphene. A slight increment in thermal diffusivity was observed due to a smoother phonon transition at the graphene matrix interface.