Effects of Cr and Ta Additions on Immersion Corrosion and Electrochemical Behaviors of Laser Cladded Fe90-6%Al2O3 Coating.

Fe90-6%Al₂O₃ coatings with the respective Cr and Ta mass fraction of 10% were prepared on Q235 steel by laser cladding. The microstructure, chemical elementals, surface roughness and phases of obtained coatings were analyzed using an optical microscope, energy-dispersive spectrometer, atomic force microscope and x-ray diffraction, respectively. The effects of Cr and Ta on the immersion corrosion and electrochemical performances of Fe90-6%Al₂O₃ coating in 3.5% NaCl solution were investigated using an electrochemical workstation, and the corrosion mechanism was discussed in detail. The results show that the (Fe90-6%Al₂O₃)-10%Cr coating has highest immersion corrosion resistance among the three kinds of coatings, and the corrosion mechanism of Fe90-6%Al₂O₃ and (Fe90-6%Al₂O₃)-10%Cr coatings is combined intergranular corrosion and pitting corrosion; while that of (Fe90-6%Al₂O₃)-10%Ta coating is intergranular corrosion and local crevice corrosion. Moreover, the polarization resistance of Fe90-6%Al₂O₃, (Fe90-6%Al₂O₃)-10%Cr, and -10%Ta coatings is 3.31 × 10⁴, 3.95 × 10⁴, and 4.11 × 10⁴ Ω cm², respectively, and the corresponding charge transfer resistance is 10280, 16460, and 16990 Ω cm², respectively, showing that the (Fe90-6%Al₂O₃)-10%Ta coating has the best electrochemical corrosion resistance. [ABSTRACT FROM AUTHOR]