Wear behavior of the raw and pre-smashed carbon nanotubes reinforced 6061Al composites fabricated by powder metallurgy

The raw and pre-smashed (PS) carbon nanotube (CNT) reinforced 6061Al composites (CNT/6061Al) with different CNT contents were respectively fabricated by powder metallurgy technology. It was found that reducing the CNT cluster size by pre-smashing processing could sharply reduce the friction coefficient, and significantly improve the density, hardness, and wear resistance of the CNT/6061Al composites. For the raw-CNT/6061Al composites, the wear rate increased approximately linear trend while the CNT content was over 1 wt.%. The plastic deformation, deep grooves, and serious delamination were presented on the wear surface. The wear process was gradually transformed from Al-copper base counterpart wear into Al-Al wear for the higher adhesion-binding energy between aluminum and copper base counterpart. While for the PS-CNT/6061Al composites, the wear rate gradually decreased as the CNT content increased from 0 to 2 wt.%. This was mainly because the generation of the thinner mechanically mixed layer (MML) and the PS-CNT prevented the direct contact between specimen and copper base counterpart, which effectively inhibited the adhesive wear. But excessive PS-CNT addition (∼3 wt.%) would weaken the bonding between CNT and 6061Al, and thus the wear resistance of the composite was reduced apparently.