Nanoscratch behavior of carbon nanotube reinforced aluminum coatings

Nanoscratch experiments have been carried out on plasma sprayed aluminum alloy coatings reinforced with 0, 5 and 10 wt.% carbon nanotubes (CNTs). Scratches have been performed at loads of 1000, 2000 and 3000 μN load using Berkovich indenter. The contact and true wear volumes of the scratches have been calculated. The nano-scale wear resistance is shown to increase by 4 times by addition of 10 wt.% CNTs. Improvement in the wear resistance is discussed with respect to strengthening effect and increased elastic recovery by addition of CNTs. Direct evidence of increased recovery and small decrease in the coefficient of friction with CNT content is provided using the true and instantaneous depth plots and the corresponding scanning probe microscope and scanning electron microscope images of the scratches. Friction coefficient was found to be load independent and was found to vary slightly with the CNT content.