Upcycling eggshell waste for enhanced multifunctional performance of AA7075 alloy

Abstract

This study examines the potential for using eggshell waste as a green reinforcing material to enhance the mechanical and electrochemical properties of AA7075 aluminum alloy. Eggshell particulate was incorporated in the alloy with various weight fractions (1.5–10 %) by the stir casting technique. The composites formed were then tested for tensile, compressive, impact, hardness, and electrochemical tests to determine their performance. Tensile strength was improved by a maximum of 15.52 % at 10 % reinforcement with eggshells, but compressive strength was maximum at 7 % reinforcement and was improved by 15.26 %. Impact resistance improved marginally at 7 % reinforcement but decreased at higher percentages due to agglomeration of particles. The hardness values improved significantly to the maximum level at 5 % reinforcement. Electrochemical tests performed in acidic (1 M HCl) and alkaline (3.65 % NaCl) environments revealed greater corrosion resistance with the lowest rate of corrosion observed in the sample having 10 % reinforcement. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) further confirmed homogeneous particle distribution and better interfacial bonding. The current investigation confirms that eggshell-reinforced AA7075 composites are a green alternative to industrial use, combining better mechanical properties and environmental sustainability.