Microstructure, Tribocorrosion and Corrosion Performances of Laser Cladded Ni625-xTiC Coatings in 3.5% NaCl Solution.

Ni625-xTiC coatings were prepared on 45 steel by laser cladding to improve its corrosive-wear and electrochemical performances. The microstructure, phase composition and hardness of obtained coatings were analyzed using a super-depth field microscope, x-ray diffraction, and microhardness tester, respectively. The effects of TiC mass fraction on the corrosive-wear and electrochemical behaviors in 3.5% NaCl solution were investigated. The results show that the Ni625-xTiC coatings are mainly composed of γ-Ni, TiC, Cr₂₃C₆, Cr₇C₃, Fe₃Mo, FeTi and Nb₂C phases, and the coating hardness increases with the TiC mass fraction, which is 3 times that of substrate. The wear rates of Ni625-0%TiC, -5%TiC, -10%TiC and -15%TiC coatings are 65.86, 55.09, 47.92 and 42.15 μm³ mm⁻¹ N⁻¹, respectively, showing that the wear resistance of Ni625-15%TiC coating is the best. The wear mechanism is primary abrasive wear, accompanied with adhesive wear and pitting corrosion. Moreover, the polarization resistance R_p of Ni625-0%TiC, -5%TiC, -10%TiC and -15%TiC coatings is 1.136 × 10⁵, 1.459 × 10⁵, 8.619 × 10⁴, 5.698 × 10⁴ Ω cm², respectively, showing that the Ni625-5%TiC has the best corrosion resistance. [ABSTRACT FROM AUTHOR]