Effect of Ti mass fraction on microstructure, salt spray corrosion and electrochemical performances of laser cladded Fe90–6%Al2O3 coatings

Abstract

Fe90–6%Al2O3 coatings with the different Ti mass fractions were prepared on S355 steel by laser cladding (LC). The effects of Ti mass fraction on the microstructure and phase composition of obtained coatings were analyzed, and the salt spray corrosion (SSC) and electrochemical performance were analyzed using a salt spray tester, potentiodynamic polarization curve (PPC) and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results demonstrate that the microstructure of (Fe90–6%Al2O3)–Ti coating becomes more compact by the addition of Ti, which is composed of Fe–Cr with the cubic crystal plane. The corrosion resistance of laser cladded (Fe90–6%Al2O3)–Ti coatings increase with the Ti mass fraction, which is contributed to the formation of Fe–Cr phase. The Fe90–6%Al2O3–15%Ti coating with the largest polarization resistance of 3.81 × 105 Ω exhibits the highest corrosion resistance among the three kinds, in which the passive films of Cr and Ti with the N–type semiconductor play the role of corrosion resistance.