Effects of laser power on corrosion behaviors of laser thermal sprayed Al–Ti–Ni amorphous coatings in H2SO4 and NaOH solutions

Abstract

Amorphous Al–Ti–Ni coatings were fabricated on S355 steel using a laser thermal spraying (LTS). The surface and cross–section morphologies, chemical compositions and phases of obtained coatings were analyzed using a field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), and x–ray diffraction (XRD), respectively. The effects of laser power on the immersion corrosion and polarization curves in 0.1 M H2SO4 and 0.1 M NaOH solutions were investigated using a salt spray corrosion (SSC) chamber and electrochemical workstation. The results show that the amorphous Al–Ti–Ni coatings are primarily composed of AlFe3, AlFe, Ni2MnAl, AlCrFe2, and Al2O3 with the amorphous structure, which form the metallurgical bonding at the coating interface. The Al2O3 film on Al–Ti–Ni coating is destroyed severely by the aggressive H+ in 0.1 M H2SO4 solution, leading to the higher corrosion rate, the lowest corrosion current density and highest polarization resistance of Al–Ti–Ni coating fabricated at the laser power of 1500 W are 1.722 × 10–4 A·cm–2 and 195 Ω, respectively, whose corrosion rate is the lowest. While those fabricated at the laser power of 1700 W in 0.1 M NaOH solution are 2.484 × 10–6 A·cm–2 and 15 243 Ω, respectively, its corrosion resistance is the best among the three kinds of coatings.