Multi-response optimization of physical, mechanical and tribological properties of alumina and graphite-reinforced aluminium matrix composites

This study investigates the physical (density, porosity), mechanical (hardness, compressive strength) and tribological (wear loss, coefficient of friction) properties of aluminium metal matrix composites reinforced by the varied amount of alumina and graphite particles fabricated via the powder metallurgy process. The density increased with the incorporation of alumina and decreased with the incorporation of graphite. The porosity of the composites increased with the increase in of reinforcements due to poor wettability and low compaction pressure during the experiments. The experimental investigations revealed that the hardness and compressive strength increased with an increase in alumina content due to high hardness of alumina particles. Nevertheless, the wear loss and coefficient of friction of the composite decreased with an increase in graphite content due to its lubricating properties. The microstructural study revealed a uniform distribution of reinforcement in the composite, with debonding and wetting occurring at high alumina content. The Taguchi L16 orthogonal array has been utilized to plan and design experiments by selecting different factors (alumina content, graphite content, compaction pressure, compaction time, milling time, load, sliding speed) at four levels. The optimizations of process parameters were done through grey relational analysis.