Tribological performance and RSM-based optimization of sustainable aluminium composites using bio- and industrial waste reinforcements

Abstract The growing demand for lightweight and durable materials in automotive, marine, and industrial machinery applications has intensified interest in aluminium metal matrix composites (MMCs). However, producing high wear resistance composites while preserving sustainability is a significant challenge. This study develops and evaluates the tribological performance of sustainable aluminium MMCs reinforced with bio-driven coconut shell ash (CSA) and aluminium waste red mud (RM) materials for engineering applications. Stir-casting was used to produce sustainable composites with RM and CSA particle reinforcements (2–6 wt. %). The wear rate and friction coefficient were evaluated at a constant sliding distance of 1500 m under varying loads (40–60 N) and speeds (300–500 rpm). The composite samples were evaluated using energy dispersive x-ray analysis and scanning electron microscope, and their surface roughness and textural characteristics were further examined by 3D-surface topography analysis. Moreover, DoE-RSM optimization techniques were utilized to optimize the reinforcement composition and wear parameters. Experimental results showed that the wear rate and surface roughness of 4 wt. % sustainable composites decreased by 73.64% and 24.3%, respectively, as compared to base alloy materials. The tensile strength of 4-wt% hybrid reinforced composites increased by 17.9% when compared to the base alloy aluminium material. Moreover, the DOE analysis identified the optimal values as a reinforcement concentration of 3.98%, a sliding speed of 300 rpm, and a sliding load of 47 N for providing the lowest wear rate, which has been validated through experiments. Subsequently, future directions are indicated that could lead to more efficient and superior wear performance of sustainably reinforced MMCs.