Tribological Behaviour of Al6061–2SiC-xGr Hybrid Metal Matrix Nanocomposites Fabricated through Ultrasonically Assisted Stir Casting Technique

This study deals with the tribological properties of 2 wt.% of SiC and x wt.% of Gr (x = 0, 0.5, 1, 1.5, 2, and 3) nanoparticles reinforced Al6061 alloy fabricated through ultrasonically assisted casting technique. Microstructure, various elements, particle sizes, phases, worn surfaces, wear debris are analyzed to understand the tribological behaviour of hybrid nanocomposites. Microstructural studies revealed the uniform dispersion of SiC and Gr nano-reinforcements in the matrix. Nano-clusters appeared in the micrographs with the increase of Gr nanoparticles. Density and microhardness of Al6061–2SiC-xGr hybrid nanocomposites decreased with the rise of Gr in the composite material. Influence of Gr content on the wear rate and coefficient of friction of hybrid nanocomposites are studied. Pin-on-disc apparatus is used to carry out the experiments at 5–20 N normal load, 0.5–2 m/s sliding velocity and 1000–3000 m sliding distance. The wear rate and coefficient of friction of hybrid nanocomposites reduced with the rise of nano Gr content up to a critical value and then increased. The reduction of wear rate for Al6061–2SiC-xGr (x = 0.5, 1, 1.5, 2, and 3) hybrid nanocomposites compared to AA6061 alloy at higher tribological conditions is 20%, 40.2%, 47.3%, 57%, 73%, and 64% respectively. Similarly the reduction in coefficient of friction for Al6061–2SiC-xGr (x = 0.5, 1, 1.5, 2, and 3) hybrid nanocomposites compared to Al6061 alloy is 3%, 5.9%, 11.8%, 17.7% and 9% respectively. The wear debris size decreased with the rise of Gr content in the Al6061–2SiC nanocomposite.