Effect of SiC Nanoparticles on the Microstructural and Physico-Mechanical Properties of Agro-Bio-Wastes (RHA–ESA) Reinforced T6 Heat Treated Al Hybrid Nanocomposite

This study investigates the development of environmentally friendly aluminum hybrid nanocomposites by reinforcing Al 7075 alloy with rice husk ash (RHA), eggshell ash (ESA), and varying amounts of silicon carbide (SiC) nanoparticles. The goal is to evaluate the effects of SiC concentration on the composites’ physical, mechanical, and microstructural properties, emphasizing the use of agricultural waste for sustainable innovation. The base matrix, Al 7075, was reinforced with 3.75 wt. % RHA and 1.25 wt. % ESA (75–100 microns), along with 0.5 to 2.5 wt. % of < 80 nm SiC nanoparticles. Fabrication involved ultrasonic cavitation-assisted stir casting, followed by squeeze casting. Post-processing included solution treatment, quenching, and T6 aging. Density and porosity were measured using Archimedes’ principle and theoretical models. Mechanical testing covered hardness, tensile and yield strength, toughness, compressive and flexural strength. Microstructural evaluation employed optical microscopy, FESEM, EDAX, and XRD, while fracture analysis identified failure mechanisms. Results showed significant performance improvements with up to 2.5 wt. % SiC: hardness increased by 40%, tensile strength from 277 to 493 MPa, and toughness from 23 MJ/m3 to 48 MJ/m3. Improved particle dispersion, interfacial bonding, and grain refinement were observed, though porosity slightly increased at higher SiC content. Phase analysis confirmed the presence of Al, SiO₂, SiC, CaO, MgZn₂, and Mg₂Si. Fracture surfaces showed both ductile and brittle modes. The study demonstrates that using agro-waste with SiC nanoparticles can yield sustainable, high-performance aluminum composites.