Impact of Alumina-Graphene nanoplatelets on the microstructure, corrosion behaviour, & mechanical properties of cast aluminium nanocomposite by Vortex technique

In this work, the impact of reinforcing aluminum matrix with a nano-hybrid Al2O3-GNS nanosheet and the rolling process of the prepared composites were studied. Al2O3-GNS nanocomposite powder of a 98% to 2% ratio was produced by powder mechanical milling for 24 h. Additionally, the hybrid mixture undergoes surface treatment by coating with 10% silver to improve its wettability. For the nanocomposite production, aluminum scrap was melted at 800 °C, and the hybrid nanoparticles were added to the aluminum melt in 0%, 5%, 10%, and 15% by weight, followed by mechanical stirring at 600 rpm for 10 min. Then, hot-rolling was conducted for the cast billets to ensure optimal distribution of the hybrid nanoparticles. The microstructure, hardness, and wear rate were studied before and after the hot rolling process. Scanning electron microscopy (SEM) and Raman spectroscopy were used to analyze the microstructure. For mechanical properties, hardness, tensile strength, and wear resistance were measured. Additionally, corrosion resistance was evaluated. The microstructural analysis reveals a well-distributed hybrid phase within the aluminum matrix, with strong adhesion between the nanoparticles and the base metal. The incorporation of Al₂O₃–GNS hybrid nanoplatelets led to a significant enhancement in the mechanical and corrosion properties of recycled aluminum. The hardness increased from 72.3 HV for pure aluminum to 168.7 HV for the hot-rolled composite containing 15 wt% Al₂O₃–GNS, while the ultimate tensile strength improved from 55.8 MPa to 139.9 MPa after rolling. Furthermore, the corrosion rate in 3.5 wt% NaCl solution was reduced from 3.124 mm/year for pure aluminum to 0.215 mm/year for the as-cast reinforced composite, corresponding to a 93% improvement in corrosion resistance. The findings of this work contribute to the development of advanced materials with superior performance, offering potential applications in industries where high strength and corrosion resistance are critical.