Corrosion behavior of sealant-treated Fe-based amorphous coatings in simulated desulfurization acidic environments

Fe-based amorphous alloy coatings were successfully deposited on the surface of Q235 steel using high-velocity oxygen-fuel spraying technology. The Fe-based amorphous coatings were sealed using epoxy resin, polytetrafluoroethylene (PTFE) resin, SiO2 sol, and aluminum phosphate. The four types of coatings were compared to investigate the corrosion performance of the sealed coatings in a 5 wt. % H2SO4 solution, and the corrosion protection failure mechanisms of the coatings before and after sealing were analyzed. Corrosion tests were conducted on the specimens using an electrochemical workstation, and the corrosion products and corrosion morphology of the coatings were analyzed and observed. The sealing effects of the four sealing agents—epoxy resin, PTFE resin, SiO2 sol, and aluminum phosphate—were systematically compared, and the variation in the performance of the optimal sealing coating with respect to the concentration of the corrosive medium was thoroughly investigated. The results indicate that coatings sealed with aluminum phosphate exhibit the best corrosion resistance in H2SO4 solutions; however, as the concentration of H2SO4 increases, the effectiveness of the sealing agent in enhancing the coating’s corrosion resistance gradually decreases. This work provides useful insights for improving the corrosion resistance of Fe-based amorphous coatings, thus facilitating their potential application in more demanding environments.