Effects of CeO2 nanoparticles on microstructure and properties of laser cladded NiCoCrAlY coatings

CeO2 nanoparticles (nano-CeO2p) were added into laser cladded NiCoCrAlY coatings on Ni-based superalloy substrate to improve the microstructure and properties. Scanning electron microscope (SEM), X-ray diffractometer (XRD), micro-hardness tester, and heat treatment furnace were employed to investigate their morphologies, phases, micro-hardness and thermal shock resistance, compared with the coating without nanoparticles added. The results showed that the microstructure and properties of the coatings with the addition of nano-CeO2p were better than the coating without nanoparticles added, in which the coating with the addition of 2.0 wt.% nano-CeO2p showed the most significant improvement effects. With the addition of nano-CeO2p, the growth pattern of interface grain was changed, the microstructure of cladding layer was refined, and the solid solubility of Cr was increased. These changes of microstructure after adding nano-CeO2p improved micro-hardness and its distribution uniformity on the cross section, and the thermal shock resistance as well.