Correlation between theoretical and experimental hardness, elastic modulus of discarded aluminium piston reinforced with zirconium diboride and snail shells

Abstract

Aluminium metal matrix composites have gained a lot of attention because of their outstanding properties making them useful for aerospace, automobile and marine applications. Composites are replacing metals as structural materials, and a detailed study of the relationship between hardness and Young’s modulus becomes essential. In this paper, the correlation between hardness and elastic modulus of discarded aluminum pistons reinforced with zirconium diboride and snail shells is presented. The theoretical hardness was determined from the ratio of indentation hardness to indentation modulus while elastic modulus was evaluated based on composite equation. The results indicated that hardness and elastic modulus increased with the weight percentage of the composites while the resistance to plastic deformation H3/E2 increased with H. The wide discrepancy between the theoretical and experimental Young’s modulus is attributed to the fact that theoretical elastic moduli were obtained from perfect/single crystal materials while experimental values are obtained from polycrystalline/imperfect crystals. The calculated Young’s moduli obtained through mixture rule range from 64 to 92 GPa which are higher than 69 GPa of aluminium alloy. It is therefore evident that the composite materials can be used for engineering applications.