Effects of carbonised eggshells on the mechanical properties, microstructure and corrosion resistance of AA1050 of metal matrix composites

The application of aluminium matrix composites (AMCs) is receiving increased attention due to their improved mechanical and corrosion properties. To this effect, this work was conducted to investigate the effect of carbonised eggshells on the microstructure, density and corrosion resistance of AA 1050. Carbonised eggshells were selected as the reinforcing phase due to its abundance, ease of preparation and most importantly for environmental sustainability. The selected fabrication route for the composite was stir casting. The weight fraction of the carbonised eggshells was varied at 2 wt%, 4 wt%, 6 wt% and 8 wt% in the aluminium alloy. The examination of the microstructure revealed a fair distribution of the reinforcements in the aluminium matrix. Evaluation of the experimental density obtained via Archimedes principle reported a decline with increasing weight fraction of the carbonised eggshells showing its capabilities of producing lightweight components. The analysis of the tensile strength revealed 11.04%, 8.41%, 0.95% and 1.01% improvements, respectively, for the 2 wt%, 4 wt%, 6 wt% and 8 wt%, respectively. The analysis of the compressive strength revealed improvements of all the cast AMC in comparison to the base metal except for the 6 wt% samples which showed a 31.9% decrease in comparison to the aluminium alloy. The microhardness improved with increasing weight fraction of the carbonised eggshell particles up to 8 wt%. The investigation into the corrosion-resistant properties of the casts revealed that the 8 wt% sample displayed the least corrosion rate of 7.72 × 10⁻⁶ g/h which indicates that the sample has the best corrosion resistance in comparison to the other cast samples.