Carbon nanotubes improves the tribological properties of Ni60/Al2O3 coatings

Carbon nanotubes (CNTs) was introduced into Ni60/Al2O3 coating by flame spraying. The effect of adding CNTs on the tribological properties of the coating was studied by varying the CNTs content as 0.0, 1.5, 3.0 and 4.5 wt% in the Ni60/Al2O3 powders. The microhardness tester was used to measure the microhardness of the coating. Wear tests were performed on a pin-on-disk tribometer, to evaluate the tribological properties of the Ni60/Al2O3/CNTs coatings. Microstructural characterization was performed using scanning and transmission electron microscopy. Ni60/Al2O3/CNTs coatings revealed a lower wear rate and friction coefficient compared with the original coating, and their wear rates and friction coefficients showed a decreasing trend with increasing mass fraction of CNTs within the range from 0 to 3.0 wt% due to the effects of the reinforcement and reduced friction of CNTs. The results showed that the CNTs played dual roles in improving the tribological performance of the coating, indirectly by influencing the microstructure and mechanical properties of the coating and directly by acting as a lubricating medium.