Study on the Microstructure and Microhardness Behavior of Reduced Graphene Oxide Reinforced Alumina Nanocomposites

Abstract

Here, we report the successful development of reduced graphene oxide (rGO) (0.1, 0.3 and 0.9 wt.%) reinforced alumina (Al2O3) novel nanocomposites by powder metallurgy route. The composite powder samples were prepared using a high-energy dry planetary ball mill for 2 h under an argon atmosphere. Then, the optimized compacted samples (at 170 MPa for 180 s) having high density were sintered at 1450 degrees C for 180 min. under an argon atmosphere. The characteristics of the materials have been evaluated to improve microstructure, microhardness, and Young's modulus of composites. rGO has 4-5 numbers of graphene sheets with an energy band gap of 2.28 eV and a specific surface area of 509.177 m2/g. The rGO retains structural quality before and after making composites with Al2O3 samples. The purity of rGO and Al2O3/rGO composite samples was confirmed by EDS analysis. While rGO shows peaks of C and O, Al2O3/rGO (0.1, 0.3, and 0.9 wt.%) composite samples show peaks of Al, O, and C. Micro Raman analysis establishes the successful formation of composite between Al2O3 and rGO. Al2O3/rGO (0.1, 0.3, and 0.9 wt.%) composite samples mostly show similar kinds of D, G, and 2D peaks as shown by pure rGO. The outstanding result achieved for the typical Al2O3/rGO (0.3 wt.%) sample showed significantly higher microhardness (2488 +/- 12 VHN) and Young's modulus (520 +/- 9 GPa) values compared to pure Al2O3. The microhardness and Young's modulus values of Al2O3/rGO (0.3 wt.%) composite are more than 79% and 31% compared to those observed for pure Al2O3. When the rGO amount further increased to 0.9 wt.% in Al2O3, agglomeration of graphene sheets developed, which caused degradation of the mechanical property of the composite. The excellent outcome of this work further advances critical applications of Al2O3 in various industrial fields.