In this study, Fe40Cr19Mo18C15B8 amorphous coatings were prepared using high velocity oxygen fuel (HVOF) technology. Different temperatures were used in the heat treatment (600 °C, 650 °C, and 700 °C) and the annealed coatings were analyzed by DSC, SEM, TEM, and XRD. XRD and DSC results showed that the coating started to form a crystalline structure after annealing at 650 °C. From the SEM observation, it can be found that when the annealing temperature of the Fe-based amorphous alloy coating reached 700 °C, the surface morphology of the coating became relatively flat. TEM observation showed that when the annealing temperature of the Fe-based amorphous alloy coating was 700 °C, crystal grains in the coating recrystallized with a grain size of 5-20 nm. SAED analysis showed that the precipitated carbide phase was M23C6 phase with different crystal orientations (M = Fe, Cr, Mo). Finally, the corrosion polarization curve showed that the corrosion current density of the coating after annealing only increased by 9.13 μA/cm2, which indicated that the coating after annealing treatment still had excellent corrosion resistance. It also proved that the Fe-based amorphous alloy coating can be used in high-temperature environments. XPS analysis showed that after annealing FeO and Fe2O3 oxide components increased, and the formation of a large number of crystals in the coating resulted in a decrease in corrosion resistance.
Keywords: HVOF; amorphous structure; corrosion; heat treatment.