Sustainable agro-waste ash reinforced aluminium matrix composites with emerging potential of nano-banana peel ash in Al7075

The development of sustainable aluminium matrix composites using agricultural waste-derived reinforcements provides an alternative approach to utilizing biomass residues in advanced engineering materials. In this study, nanoscale banana peel ash (Nano-BPA) was synthesized through dehydration, calcination, and high-energy ball milling and incorporated into an Al7075 alloy by stir casting. Nano-BPA was characterized using particle size analysis (PSA), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and thermogravimetric analysis (TGA). The Al7075 base alloy and composites containing 2 and 4 wt% Nano-BPA were fabricated and evaluated under dry sliding wear, Charpy impact, and immersion corrosion conditions. Particle size analysis yielded a D50 value of 20.2 nm, with D10 and D90 values of 12.4 and 33.8 nm, respectively. The specific wear rate decreased from 1.160 × 10⁻⁴ mm³/(N·m) for Al7075 to 8.456 × 10⁻⁵ and 3.315 × 10⁻⁵ mm³/(N·m) for the 2 and 4 wt% Nano-BPA composites, respectively. The absorbed impact energy increased from 5.5 ± 0.20 J for Al7075 to 7.0 ± 0.25 and 8.0 ± 0.30 J for the 2 and 4 wt% Nano-BPA composites, respectively. After 72 h of immersion in a 3.5 wt% NaCl solution, the measured corrosion rate decreased from 0.649 ± 0.027 mm/year for Al7075 to 0.460 ± 0.027 and 0.203 ± 0.014 mm/year for the 2 and 4 wt% Nano-BPA composites, respectively. Among the investigated compositions, the 4 wt% Nano-BPA composite exhibited the best overall measured performance. These results demonstrate the feasibility of Nano-BPA as a sustainable reinforcement for improving the experimentally evaluated wear, impact, and corrosion performance of Al7075 composites.