Characterization of waste eggshells and CaCO3 reinforced AA2014 green metal matrix composites: A green approach in the synthesis of composites

Three AA2014 alloy metal matrix composites containing reinforcing particles of eggshell, carbonized eggshell and CaCO3 (powder) were processed. The influences of different particle percentage of eggshell were compared with commercial calcium carbonate. The electromagnetic stir casting technique followed by hot extrusion was employed to fabricate metal matrix composite. The results revealed that the tensile strength, hardness and fatigue strength increased by the addition of eggshell particles up to 12.5 wt.% in AA2014 matrix alloy for both carbonized and uncarbonized reinforced composites. Toughness, ductility and corrosion rate decreased by the addition of eggshell particles up to 12.5 wt.% in AA2014 matrix alloy for both carbonized and uncarbonized reinforced composites. Mechanical properties decreased in the addition CaCO3 in AA2014 matrix alloy. After the heat treatment process, mechanical properties further improved for both carbonized and uncarbonized eggshell particles reinforced composites. However, corrosion rate increased. These results showed that using the carbonized eggshell as reinforcement in the AA2014 alloy gave better physical and mechanical properties at lower cost as compared to uncarbonized ES particles and CaCO3. Apparent interfacial reaction layer and minimum corrosion were observed at AA2014/12.5% carbonized eggshell particulate composite. No reaction product was observed at AA2014/CaCO3 particulate metal matrix composite.