Corrosion resistance of chromium-free conversion coatings deposited on electrogalvanized steel from potassium hexafluorotitanate(IV) containing bath

Chromium-free conversion coatings were deposited from a bath containing potassium hexafluorotitanate(IV). The substrate was electrogalvanized carbon steel. The obtained coatings had a microspheroidal structure and were homogenous. An XPS analysis showed that the coatings were composed of: oxides, hydroxides, phosphates, carbonates and fluorocompounds. As part of this study, the influence of coating deposition time on the surface morphology, chemical composition and physicomechanical properties of the samples was examined. DC polarization measurements, electrochemical impedance spectroscopy and neutral salt spray tests showed that the investigated Cr-free coatings markedly increase the corrosion resistance of electrogalvanized steel in a chloride environment.