Enhanced physical properties of gamma-Al2O3-rGO hybrids prepared by solvothermal and hot-press processing

In this study, a solvothermal method was employed for the first time to fabricate hybrids composed of crosslinked gamma-Al2O3 nanorods and reduced graphite oxide (rGO) platelets. After calcination and hot-press processing, monoliths of Al2O3-rGO hybrids were obtained with improved physical properties. It was found that the oxygen-containing groups on graphene oxide were beneficial for the adsorption of aluminum isopropoxide, leading to a uniform dispersion of rGO with Al2O3, which was obtained by hydrolysis of aluminum isopropoxide during the solvothermal reaction. The hybrid, which was subsequently calcinated for 3 h showed electrical conductivity of 6.7 x 10(1) S m(-1) together with 90% higher mechanical tensile strength and 80% higher thermal conductivity as compared to the bare Al2O3. In addition, the dielectric constant of the hybrid was 12 times higher than that of the bare Al2O3. In this study, the highest values of electrical conductivity (8.2 x 101 S m(-1)), thermal conductivity (2.53 W m(-1) K-1), dielectric constant (104) and Young's modulus (3.7 GPa) were obtained for the alumina-rGO hybrid calcinated for 1 h. XRD characterization showed that an increase in calcination temperature and further hot-press processing at 900 degrees C led to enhanced crystallinity in the gamma-Al2O3 nanorods in the hybrid, resulting in enhanced physical properties in the hybrids.