Fabrication and characterization of Ag coated Al2O3/GNs reinforced Cu nanocomposites for renewable energy applications

Abstract

The utilization of renewable energy has become increasingly significant recently, yet it encounters great challenges. The present study focuses on enhancing the performance of copper-based nanocomposites for wind energy applications by achieving a desirable combination of wear resistance and electrical properties. The investigation explores the effects of graphite exfoliation and silver reinforcement coating on the properties of the composite. Cu–Ag-(C/Al2O3) nanocomposites are fabricated, varying the percentage of Al2O3 from 0 to 12.5% in increments of 2.5%. The study involves physical, electrical, mechanical, and tribological analyses, along with extensive metallography using techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and mapping. The results demonstrate significant enhancements in the composite properties with higher percentages of Al2O3, up to a limit of 10%. The inclusion of a hybrid reinforcement consisting of 10% Al2O3 and 5% exfoliated graphene, along with a 20% silver coating, results in a lighter-weight Cu-composite with 98% of the electrical conductivity of copper (IACS). Moreover, this composite exhibits the highest hardness (365 HV), which is six times greater than the hardness of the composite without the reinforcement (60 HV). The composite containing 10% Al2O3 exhibits the lowest wear rate (3.5 × 10−6 (mm3/m)), while the composite without Al2O3 demonstrates the highest wear rate (6.7 × 10−6 (mm3/m)). Metallographic analysis confirms the formation of graphene through exfoliation. The presence of graphene not only improves the coefficient of thermal expansion (CTE) stability due to its lubricating effect but also enhances the electrical conductivity of the composites when combined with the silver reinforcement coating.