Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ-Al2O3 by Adding Graphene Nanoplatelets

Abstract

[EN] One of the main challenges to widen the potential applications of 3D printed highly porous ceramic structures in catalysis, energy storage or thermal management resides in the improvement of both their mechanical resistance and thermal conductivity. To achieve these goals, highly hierarchical γ-alumina (γ-AlO) scaffolds containing up to 18 vol% of graphene nanoplatelets (GNP), including channels of controlled size and shape in the millimeter scale and meso-porosity within the rods, are developed by robocasting from boehmite-based aqueous inks without other printing additives. These 3D structures exhibit high porosity (85%) and specific surface area of 100 m g. The incorporation of 12 vol% GNP leads to an enhanced mechanical response of the scaffolds, increasing the compressive strength and the elastic modulus up to ≈80% as compared with data for plain γ-AlO scaffolds. The thermal conductivity is measured by the transient plane source method using specifically designed 3D structures with external sidewalls and additional top/bottom covers to assure a good contact at the outer surfaces. The thermal conductivity of 3D porous structures augments with the GNP content, reaching a maximum value four times higher for the scaffolds containing 18 vol% GNP than that attained for the 3D monolithic γ-AlO.