Mechanical and tribological performance of rice husk ash and eggshell powder reinforced sustainable composites

Heightened concerns over the exhaustion of natural mineral resources, escalating waste accumulation, and the need for lightweight materials to meet strict emission norms have spurred growing interest in sustainable aluminium-based composites. In this work, a hybrid aluminum matrix composite was developed using Al6063 as the base material and agricultural waste-derived eggshell powder (ESP) and rice husk ash (RHA) as reinforcing phases. The composites were manufactured via stir casting by varying the RHA content between 1 and 5 wt% and the ESP content between 2 and 10 wt%. The addition of ESP and RHA decreased material density while simultaneously enhancing mechanical and tribological characteristics. Compared with unreinforced Al6063, Rockwell hardness improvements of 12%, 16%, 20%, 32%, and 24% were observed, with the highest increase of 32% for the S2 composite. Compression strength showed remarkable enhancement, exhibiting increases of 409.22%, 663.8%, 361.48%, 90.96%, and 154.61% relative to the base alloy. Microstructural investigations revealed uniform dispersion of the reinforcement particles throughout the aluminum matrix, and fractographic analysis indicated a predominantly brittle fracture mechanism. The results demonstrate the potential of using low-cost agricultural waste materials to produce lightweight, cost-effective, and environmentally sustainable aluminium matrix composites suitable for advanced engineering applications.