Effect of CNT content on the microstructure and friction characteristics of DED-fabricated CNTs-Ni60/WC coatings

The microstructure and tribological behavior of CNTs-reinforced Ni60/WC composites fabricated by directed energy deposition (DED) are studied. The effect of CNTs content is investigated and compared to that of a CNTs-free composite sample. The improvement of hardness, thermal stability, and wear resistance caused by microstructural refinement is observed in the CNTs reinforced composites. Different additions of CNTs may be responsible for the aforementioned performances. The microstructure and micro-protrusions growth characteristics are investigated using SEM and AFM, linked to the CNTs content, which refines the microstructure. The hardness, TG/DSC, and friction coefficient curves establish 1.5 wt% CNTs as the optimal addition amount. Additionally, the tribological characteristics are discussed based on the wear behavior and wear scar EDS analysis. The main friction mechanisms of the composites are abrasive wear and adhesive wear. The wear loss reduction peaked at 67.9 % in the 1.5 wt% CNTs-Ni60/WC composites. The mechanical properties of the coating are improved by CNTs. This clearly demonstrates the guiding significance of CNTs-reinforced composites for tribological development.