Wet ball milling and subsequent high-speed selective laser sintering of Nb-Cu powders for applying wear-resistant coatings

The work investigates niobium-carbohydride- and copper-based powders prepared via wet ball milling of niobium and copper in petroleum ether, including their phase composition evolution under heat treatment. Highspeed selective laser sintering of the prepared powders on iron substrates provides gradient coatings -70 mu m thick. The outer layer of the coating contains phases of NbC0.75, Nb2C, (Fe,Nb)6C, Cu, and Fe, whereas the 10-mu m layer adjacent the substrate shows the presence of NbC0.75, (Fe,Nb)6C, Fe2Nb, Cu, and Fe. Dry friction with a WC-Co counterbody does not cause wear of the coatings, and the friction coefficient being -0.6. High wear resistance of the coatings results from their structure including regions containing nanosized niobium carbides (50-500 nm) with a hardness of -11 GPa, regions of Fe + Fe2Nb eutectic reinforced with niobium carbide inclusions with a hardness of 6.5 GPa, and copper inclusions working as a solid lubricant in tribological tests.

Automated summary

This work investigates the phase composition evolution of niobium-carbohydride- and copper-based powders prepared via wet ball milling under heat treatment. High-speed selective laser sintering on iron substrates results in gradient coatings with high wear resistance due to the presence of different hardness phases and copper inclusions working as a solid lubricant in tribological tests.