Tribological Performance of Al Alloys Dispersed with Carbon Nanotubes or Ni-Coated Carbon Nanotubes Produced by Mechanical Milling and Extrusion

The microstructure, mechanical and tribological behaviors of Al alloy (AA), Al alloy-carbon nanotubes (AC) and Al alloy-Ni-coated carbon nanotubes composites (ANC) fabricated by mechanical milling of elemental powders and subsequent hot extrusion were investigated. Dry sliding wear tests conducted at three different normal loads reveal that the wear rate increases monotonously with the load. The formation and subsequent delamination of the mechanically mixed layer indicate that the general wear mechanism is a combination of sliding and adhesion, while ripple-like worn surface features correspond to wear mode transition. The higher wear resistance exhibited by AC and ANC samples correlates well with the corresponding mechanical properties achieved through the dispersion of carbon nanotubes (CNT) and Ni-coated CNT, following the traditional Archard’s wear relationship.