Wear and dry tribological behavior of AA6061/Al₂O₃/graphite hybrid nanocomposites fabricated by stir casting

This study is aimed at optimizing the wear and dry tribological behavior of aluminum oxide (Al₂O₃) and graphite (Gr) nanoparticles-reinforced aluminum matrix hybrid nanocomposites (AMHNCs). The cost-effective stir casting method is employed to fabricate the AA6061 alloy composites with varying Al₂O₃-to-Gr weight percentage (wt.%) ratios (1:1, 1:3, 1:5, 3:1, 3:3, 3:5, 5:1, 5:3, and 5:5), while the Taguchi approach is applied during designing the experimental procedures. The effects of reinforcement content, pouring temperature, and stirring time on wear performance are then assessed. Different loads (10, 20, and 30 N) are utilized during the wear evaluations conducted, which involved a pin-on-disk apparatus set to varying speeds (200, 400, and 600 rpm). A significant reduction in wear rate and friction in the obtained AMHNCs is observed, with the lowest wear rate (5.9 ×10−3 mm3/Nm) recorded by the composite with 5 wt.% Al₂O₃ and 5 wt.% Gr processed at 700°C with 1-min stirring. The most substantial influence is exerted by Al₂O₃ content (79.56%), followed by Gr content (14.47%), pouring temperature (1.09%), and stirring time (4.88%). Microstructural analyses through field emission electron microscopy (FESEM) and energy-dispersive X-ray (EDX) confirmed uniform reinforcement dispersion, which contributed to the superior wear resistance of the AMHNCs over unreinforced alloys.