Green manufacturing of rGO-reinforced Cu-based MMCs with optimized properties through microwave hybrid heating process

Abstract

This research work used a unique microwave hybrid heating (MHH) approach to Cu-based rGO metal matrix compsoites (MMC) composites. A 2.45 GHz domestic microwave, with a maximum power level of 900 W, was utilized to melt copper powder reinforced with different proportions of reduced graphene oxide (rGO) ranging from 0.5 % to 1.5 % by weight fraction. Following this, the thermal, mechanical, and metallurgical characteristics of the composite samples were examined. The average size of the raw powder particles utilized for the casting process was approximately 30 μm for copper powder and 69.8 nm for reduced graphene oxide (rGO) powder. The processing time of Cu-based rGO decreases with an increase in reinforcement material. On the developed composite casts, a variety of characterization methods were used, including Vickers' microhardness testing, porosity, density, electrical and thermal conductivity, X-ray diffraction (XRD), and scanning electron microscopy (SEM). When compared to pure Cu, the test results showed a significant increase in hardness and thermal conductivity. In rGO-based samples, the microstructural analysis showed a uniform reinforcement distribution with finely recrystallized grains that resembled polycrystalline structures and a hexagonal solidification pattern with pure Cu. The porosity decreased from 1.09 % in pure copper to 0.79 % with the addition of 1.5 % rGO, though relative density dropped due to rGO's lower density. Thermal conductivity increased to 450 W/m.K, about 2.34 times higher than pure Cu. Vickers microhardness improved to 145.75 HV, a 2.35 times increase over pure Cu (61.7 HV).