Solidification Processing of Reduced Graphene Oxide Dispersed Aluminum Composites by Squeeze Casting

Abstract

The present paper is on the processing of Al (A356)- reduced Graphene Oxide (rGO) composites by the squeeze casting technique to obtain improved mechanical and thermal properties. Reduced graphene oxide, a two-dimensional carbon allotrope with very high mechanical properties and thermal conductivity is used as a reinforcement in A356 aluminum alloy. Graphite was initially converted to rGO using the Hummers Method. 0.3 to 0.75 wt% weight percentages of rGO were incorporated into the aluminum alloy using a combination of stir mixing in semisolid state followed by squeeze casting, a hybrid method was employed to produce rGO reinforced A356 alloy matrix composite after applying mechanical stirring for uniform dispersion. Squeeze pressure was crucial for increasing the cooling rate to get finer microstructure, and eliminating the porosity. Reduced Graphene oxide uniformly within the Al 356 alloy matrix by applying both mechanical stirring for dispersion and squeeze pressure for rapid solidification and pore free casting. The squeeze cast Al 356-0.5%rGO composites after T6 heat treatment had an increase in tensile strength from 260 MPa for A356 alloy to 346 MPa, an increase in hardness 106 BHN to 130 BHN, and a reduction in coefficient of thermal expansion (CTE) from 21.7 × 10⁻⁶/°C to 10.8 × 10⁻⁶/°C at RT-50 °C. These results suggest potential applications of these composites in high performance industrial, automotive, and aerospace sectors.