The study of NiAl–TiB2 coatings prepared by electro-thermal explosion ultrahigh speed spraying technology

NiAl–TiB2 composite coatings with 0, 10 and 20 wt.% TiB2 were synthesized on the Ni-based superalloy substrate using electro-thermal explosion ultrahigh speed spraying technology. The microstructure analysis shows that the coatings consist of submicron grains. The bond between coatings and substrate is metallic cohesion. TiB2 as a powerful reinforcement is doped in NiAl for increasing its hardness. The isothermal oxidation test is carried out for the composite coatings at 1100 °C in air. The result shows that the oxidation resistance of NiAl coating is higher than that of NiAl-10TiB2 and NiAl-20TiB2 coatings. The phases of oxides on the coatings during the process at high temperature have been analyzed by X-ray diffraction. The results show that Al2O3 and Cr2O3 coexistence on surface of NiAl coating, while Al2O3, Cr2O3, TiO2 and a small amount of NiO form on surface of NiAl–10TiB2 and NiAl–20TiB2 coatings after oxidation for 4 h.