Surface characterization and corrosion resistance of fluoferrite conversion coating on carbon steel

• Fluoferrite conversion coating is prepared on carbon steel.
• The thickness of the coating is about 73 μm.
• Salt spray test (up to 72 h salt spray time) shows good anti-corrosion performance.
• Morphology, composition and electrochemical properties are presented.

Fluoferrite conversion coating has been studied for the corrosion protection of carbon steel by using the conversion solution mainly containing potassium fluoride, ammonium persulfate and other compositions. As a summary, this paper gave the detailed properties of the conversion coating prepared with hydrogen peroxide as the best composition. The morphology, composition and corrosion resistance of the coating were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electron probe micro-analyzer (EPMA) and linear polarization, electrochemical impedance spectroscopy (EIS) and the salt spray test (SST). The results showed that the coating, mainly consisting of K3FeF6, exhibited good corrosion resistance (up to 72 h salt spray time) due to its close-packed particle structure and the great thickness (73 μm).