Enhancement of corrosion protection of AISI 201 austenitic stainless steel in acidic chloride solutions by Ce-doped TiO2 coating

Ce-doped TiO2 coatings were applied by electrodeposition on a low-nickel austenitic stainless steel (AISI 201) bearing 8 wt% Mn to improve the electrochemical properties in acidic chloride solutions. Characterization of the Ce-doped TiO2 coatings was performed by a scanning electron microscope equipped with energy dispersive X-ray spectroscopy (EDS) to study the tiny features. The corrosion behavior of the bare and coated steel was evaluated in aqueous acidic chloride solutions mixing with different chloride concentrations, 1 mol.L-1 H2SO4 with 0-1.5% NaCl. Potentiodynamic polarization tests were conducted to evaluate the corrosion characteristics, corrosion potential E-corr and corrosion current density i(corr). Further study concerning the weight loss (WL) using immersion tests for the long-term was conducted to determine the bare and corresponding coated steel's equivalent corrosion rates. It was found that the electrodeposited Ce-doped TiO2 coatings with a layer thickness of similar to 1 mu m enhance the corrosion resistance of the coated steel in the acidic chloride solutions compared to its counterpart, the bare steel. The polarization tests showed that the i(corr) of the Ce-doped TiO2 coated steel significantly declined to a half value of the bare steel. The E-corr for all coated specimens shifted to a more positive value when compared with those of the bare steel. The WL measurements displayed that the bare AISI 201 steel experiences intensive corrosion degradation in the presence of a low concentration of chloride ions. However, the Ce-doped TiO2 coatings significantly resist the aggressive chloride ions and consequently increase the corrosion resistance of the steel.