Development of TiO2/Nb2O5 Films and Evaluation of Corrosion Prevention in AISI 304

Abstract

The combination of TiO2 and Nb2O5 in thin films has proven promising for preventing the corrosion of AISI 304. The thin films are developed using sol–gel and dip‐coating techniques, followed by heat treatment. Morphological and X‐ray diffraction analyses indicate a predominant anatase phase in TiO2, and isomorphic substitution of up to 20% Nb occurs in the thin‐film composition. Phase segregation above 30% is observed. Electrochemical tests are conducted in a 2 mol L−1 HCl solution. Scanning electron microscopy reveals satisfactory thin film deposition on AISI 304 but shows the presence of regions with discontinuities. Polarization curves show a corrosion current of 128.72 μA for pure AISI 304, an average corrosion current of 0.34 μA for thin films, and an average of 6.44 μA for films with discontinuities. This significant reduction in current demonstrates the efficiency of the corrosion protection of the film at the studied concentrations because of the high corrosion inhibition percentages. Electrochemical impedance spectroscopy results suggest a high charge transfer resistance, indicating a lower corrosion rate in xTiO2 the yNb2O5 films compared to uncoated AISI 304.