Multiscale wear of plasma-sprayed carbon-nanotube-reinforced aluminum oxide nanocomposite coating

A multiple length scale wear study of plasma-sprayed Al2O3–carbon nanotube (CNT) nanocomposite coating is described. CNT content and dispersion have been shown to enhance the macro-wear resistance (pin-on-disk) by more than 49 times, and nano-wear (scratch) resistance up to 18 times. CNTs have been shown to reduce the wear of Al2O3 matrix by (i) increasing densification, (ii) CNT bridging and (iii) CNT lubrication. A strong dependence of wear volume loss on the microstructural features is described at different length scales, and the disparity of material loss observed in the macro- and nano-wear tests is explained. A wear model has been established to numerically quantify wear loss dependence in terms of bulk material properties and correlating these with wear parameters from nano-scratch testing.