Corrosion Protection and Characterization of Trimetal Oxides Nanocomposite Coated Metal Substrates Prepared by Radio Frequency Sputtering Deposition

Abstract

Titanium oxide (TiO2) represents the self-cleaning feature with a combination of photo-catalysis and photo-induced super-hydrophilicity. However, TiO2-coated carbon steel (CS) and stainless steel (SS) have not presented the corrosion protection ability and nanostructured coating stability. In the present work, we have synthesized the novel tri-metallic oxide nanocomposites based on zirconium oxide (ZrO2), zinc oxide (ZnO), and TiO2 by varying the different compositions from mechano-chemical process to improve the corrosion protection and coating stability of ZrO2/ZnO/TiO2 nanocomposites on CS and SS surfaces. Metallization was observed to the phase identification of powder samples examined by X-ray diffraction (XRD) with an average crystallite size less than 20 nm. SEM images showed distinct distribution of grains with the formation of agglomeration. The coating was made on CS and SS with a target prepared from four different compositions having a thickness around 50 nm via radio frequency sputtering to investigate the performance of coatings studied by electrochemical impedance spectroscopy (EIS). The samples were exposed to 3.5% NaCl solution for 10 days at room temperature. From the Bode plots, the impedance of ZrO2-rich composition coated CS and SS samples exhibited higher values about 3 - 4 times of magnitude than those of bare CS and SS samples at the low frequency region after 10 day immersion. Interestingly enough, the phase angle values of ZrO2-rich composition coated CS and SS samples showed around -48° and -82°, respectively, with decreasing frequency. This is because relatively denser pore surface of coating materials was performed by the uniform distribution morphologies of ZrO2/ZnO/TiO2 nanocomposites, which makes it more difficult for NaCl solution to penetrate into coating layer on CS and SS substrates. ZrO2 seems to inhibit the corrosion more strongly on the interface between NaCl solution and coating layers. ZrO2 would facilitate good corrosion protection of CS and SS coated by ZrO2/ZnO/TiO2 nanocomposites.