Effects of process parameters and carbon nanotubes content on microstructure and properties of laser cladding composite coatings using Ni-Ti-Cr-carbon nanotubes

Abstract

Abstract The Ni-Ti-Cr-carbon nanotubes (CNTs) composite coatings was successfully fabricated by laser cladding. The optical microscope was used to observe the metallographic structure of the composite coating, the phase composition of the composite layer was detected by XRD, the microstructures of the composite coatings were observed by SEM, and the point distribution and line distribution of elements were analyzed by EDS. With the increase of laser specific energy (Es) and CNTs content, the TiC enhanced particles in the composite coatings evolves into coarse dendrites. Compared with the mild steel substrate, the microhardness and wear resistance of the composite coatings are obviously improved. The maximum microhardness obtained by the composite coating is approximately 5 times that of the mild steel substrate. The increase of Es and the excessive content of CNTs will reduce the microhardness and wear resistance of the composite coatings. The in situ synthesis of TiC particles not only enhance the microhardness of the composite coatings, but also improve the wear resistance of the coatings.