Effect of sol-gel sealing treatment loaded with different cerium salts on the corrosion resistance of Fe-based amorphous coating

Porosity defects inevitably formed in the preparation of high-velocity oxy-fuel (HVOF)-sprayed Fe-based amorphous coating, which greatly affected the corrosion resistance and service lives of Fe-based amorphous coating. Sealing treatment could be an effective candidate method to alleviate the problem above. In this paper, three sealed coatings including sol-gel (SG) coating, sol-gel with cerium nitrate (SCN) coating and sol-gel with cerium tartrate (SCT) coating were applied on Fe-based amorphous coating. The influence of sealing treatment on the structure and corrosion resistance of Fe-based amorphous coating was investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and electrochemical methods. The results revealed the corrosion resistance of Fe-based amorphous coating was enhanced after sealing treatments in comparison with that of unsealed coating. However, the density of SCN coating was reduced compared with that of SG coating, although it had corrosion inhibition effect. SCT coating exhibited the best in eliminating defects and enhancing the corrosion resistance among three sealed coatings. Moreover, the combined protection mechanism of SCT coating was proposed and discussed.