Effect of graphite content on the tribological behavior of Al/2SiC/Gr hybrid nano-composites processed via mechanical milling

The influence of 0 – 7 vol.% graphite addition on the dry sliding wear characteristics of Al/2SiC/Gr hybrid nanocomposites was examined. The composites were synthesized via ball milling of Al6061, nano-sized SiC and micron-sized graphite particles followed by cold pressing and hot extrusion. While the hardness of composites decreased almost linearly with their graphite content, the samples containing 2 % and 5 % of graphite exhibited minimum values of wear rate and friction coefficient, respectively. Addition of only 2 vol.% of graphite to the Al/2SiC nanocomposite resulted in changing the wear mechanism from a combination of adhesive and abrasive micro-cutting to abrasive and delamination wear. The superior tribological properties of the hybrid nanocomposites investigated in the present study as compared to those of Al/30SiC/Gr hybrid composites containing micron-sized SiC particles are discussed.