Enhancing mechanical, structural and wear properties of Al-Mg-Si-Ni-based biocomposites: Additives of hybrid high-temperature materials and bamboo leaf particulates

Abstract

We studied the effects of hybrid bamboo leaf particulate (BLp), alumina (Al₂O₃) and zirconia (ZrO₂) concentrations on structural, mechanical, physical and wear properties of Al-based biocomposites. BLp was subjected to alkali and thermal treatment to improve its surface morphology, distribution and interaction with the Al-based alloy. The composites were made using a double layer feeding stir casting method, with reinforcements added at 2 and 4 wt% concentrations and hybrid concentrations after carbonisation. The BLPs were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray fluorescence (XRF) and scanning electron microscope/energy dispersive x-ray (SEM/EDX). The corrosion study of Al-7Mg-3Si-1.5Ni/Al₂O₃/ZrO₂/BLA biocomposites was conducted in a 1 M HCl solution, and the effects of solution temperature and immersion time were investigated using weight loss measurements at 303 K and immersion times of 1, 2, 4, 6, 8 and 10 h. FTIR spectroscopy revealed changes in BLp functional groups and molecular structure following treatment, whereas SEM and OM analysis revealed changes in particle distribution and elemental composition, indicating that the thermochemical treatment altered the crystallinity, distribution and orientation of particulate matter while improving particle surface roughness and mechanical interlocking matter. The mechanical properties of the biocomposites showed improvements in ultimate tensile strength, hardness, impact and wear resistance, with a maximum tensile strength of 235.17 MPa, hardness of 110.6 BHN, impact of 62.3 J, and a lower wear rate of 2.82 × 10⁻⁴ mm³/mm (64.08 % decrease). Density and porosity analysis revealed changes in biocomposites structure and compaction after treatment and reinforcement, with hybrid Al₂O₃/ZrO₂/BLA reinforced Al-based biocomposites recording the highest density value of 2.80 g/cm³ due to increased wettability and their porous-free structure. The difference in theoretical and experimental density values indicates the presence of porosity, with % porosity values ranging from 0.4 to 1.11. Reinforcements improved particle dispersion in biocomposites, but their effect was further enhanced in hybrid and varied systems. The hybrid Al-7Mg-3Si-1.5Ni/Al₂O₃/ZrO₂/BLA biocomposites outperformed single additions of Al₂O₃, ZrO₂ and BLA. This suggests that using alkali-treated BLp and hybrid plant-based reinforcing with high-temperature metallic materials (Al₂O₃ and ZrO₂) can significantly improve the mechanical, structural and wear properties of Al-based biocomposites.