Investigating the tribological behavior of bioinspired surfaces in agro-waste and alumina reinforced AA6063 matrix composites
Festus Ben, Peter Apata Olubambi
Abstract
The tribological behavior of three bioinspired (BI) agro-waste ashes—bean pod ash (BPA), cassava peel ash (CPA), and coconut husk ash (CHA)—integrated as reinforcements in an alumina-reinforced AA6063 matrix hybrid and monolithic composite was investigated. Studies utilizing agro-wastes for bioinspired surfaces are limited despite these wastes posing significant environmental challenges. Consequently, there has been a growing effort to valorize these residues for sustainable engineering applications. This study uses a two-step stir-casting methodology to engineer bioinspired materials with lightweight properties, exceptional hardness, and wear-resistant characteristics. Microstructural investigations revealed a homogeneous distribution of natural and synthetic reinforcements within the AA6063 matrix. Lightweight AMCs were successfully fabricated, exhibiting densities ranging from 2.57 to 2.74 g/cm³ and hardness values between 81.28 and 107.47 BHN. The average surface roughness of these composites varied from 2.4 to 3.4 μm, with ANOVA tests confirming a statistically significant difference (p < 0.005). Wear rates and the coefficient of friction were observed to range from 2.52 x 10 −3 to 5.50 x 10 −3 mm³/m and 0.2476 to 0.5403, respectively. Reinforcing the AA6063 alloy with bioinspired agro-wastes significantly enhanced the hardness and tribological performance of the as-cast BI-AMCs. Notably, the wear rates and friction coefficients were significantly reduced, with the monolithic BI-AMCs demonstrating superior results. Furthermore, adding bioinspired agro-wastes, such as BPA, CPA, and CHA, improved the surface texture of AA6063 more effectively than Al 2 O 3 , leading to slightly smoother surfaces. These nuanced bioinspired tribological behaviors present opportunities for tailored load-bearing and aesthetic applications derived from agro-waste-based composites. This study advances our understanding of bioinspired tribological phenomena and paves the way for the development of innovative materials with diverse applications and enhanced performance.