Study on the corrosion resistance of KH570 modified titanium oxide coating synthesized at low temperature on 304 stainless steel

Abstract

To address the corrosion susceptibility of 304 stainless steel in chloride-containing environments, we employed a sol-gel method to prepare silica-modified amorphous titanium oxide (TiO₂) coatings with varying concentrations of KH570. The surface morphology and microstructure of the coatings were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Wettability was assessed through contact angle measurements, while corrosion resistance was evaluated via electrochemical methods and immersion corrosion tests. The results demonstrated that KH570 modification resulted in a more uniform, smoother, and denser coating surface. Notably, Ti–O–Si bonds were detected within the coating structure, with the surface transitioning from hydrophilic (contact angle of 70°) to hydrophobic (contact angle of 122°). However, increasing the concentration of KH570 adversely affected corrosion resistance due to surface roughening and diminished hydrophobicity. Excess KH570 led to incomplete grafting on the TiO₂ particles, resulting in uneven aggregation. Compared to unmodified TiO₂ coatings, the KH570-modified coatings exhibited significantly enhanced hydrophobicity, with the water contact angle of TiO₂ coatings containing 10 vol% KH570 increasing from 70° to 122°. Additionally, the KH570-modified coating demonstrated excellent corrosion resistance, characterized by a corrosion current density of 0.036 μA/cm², which is two orders of magnitude lower than that of the unmodified TiO₂ coating. Furthermore, it exhibited the highest charge transfer resistance, indicating improved electrochemical stability.