Effect of Graphite Content on Mechanical Properties and Friction Coefficient of Reinforced Aluminum Composites

Aluminum matrix composites (AMCs) reinforced with different content (wt.%) of graphite (Gr) reinforcing particles are synthesized by stir casting technique. The fraction of reinforcing particles ranges from 5 to 15 wt.% at 5 wt.% intervals. Microstructures, density, porosity, hardness, tensile strength, and friction coefficient of fabricated particulate reinforced AMCs are studied. The scanning electron microscopy reveals a non-uniform distribution of reinforcing particles in the aluminum metal matrix. A non-uniform distribution of reinforcing particles is also confirmed by the elemental maps of C (Gr) present in particulate reinforced AMCs. The density of particulate reinforced AMCs decreases from 2.69 to 2.55 g/cm(3), while the porosity increases from 0.37 to 2.45% with an increase in the fraction of reinforcing particles in the aluminum matrix from 0 to 15 wt.%, respectively. Both the hardness and ultimate tensile strength are reduced from 49.5 to 42 HV and 161.5 to 150 MPa, respectively, with a reduction in elongation from 8.6 to 6.5% with an increase in the volume fraction of reinforcing particles in the aluminum matrix from 0 to 15 wt.%, respectively. The average coefficient of friction reduced from 0.45 to 0.22 with an increase in the volume fraction of reinforcing particles in the aluminum matrix from 0 to 15 wt.%, respectively.