Effect of Isothermal Annealing on the Corrosion Resistance of Detonation Sprayed Fe-Based Amorphous Coatings

During this study, the effects of isothermal annealing on the corrosion resistance of a detonation sprayed Fe-based amorphous coating were investigated. Microscopic analysis revealed that the Fe-based amorphous coating had a relatively high porosity but lacked significant cracks. The coatings underwent isothermal annealing at different temperatures in a tube furnace, denoted as Coating A (300 °C), C (400 °C), and Coating C (500 °C). Corrosion behaviors were assessed using dynamic polarization and electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution. Results indicate that both porosity and corrosion resistance improved post-treatment. Coating C exhibited the highest corrosion potential (− 0.596 V) and lower corrosion current density (2.824 × 10⁻⁶ A/cm²). X-ray photoelectron spectroscopy (XPS) analysis identified a passivation film rich in Cr and Mo on the surface of Coating C in the solution, inhibiting Cl⁻ induced corrosion. Additionally, the low porosity of Coating C restricted Cl⁻ penetration and diffusion within the coating.