By anodization and thermal oxidation at 600 °C, an oxide layer on Ti with excellent corrosion resistance in strong acid solutions was prepared. The structural properties of TiO₂ films before and after thermal oxidation were investigated with methods of Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The electrochemical characterization was recorded via electrochemical impedance spectroscopy, potentiodynamic polarization and Mott–Schottky methods. XRD results show that a duplex rutile/anatase structure formed after oxidation, and the amount of anatase phase increased as the treatment time was prolonged from 3 to 9 h. XPS analysis indicates that as the thermal oxidation time increased, more Ti vacancies were present in the titanium oxide films, with decreased donor concentration. Longer thermal oxidation promoted the formation of hydroxides of titanium on the surface, which is helpful to improve the passive ability of the film. The anodized and thermally oxidized Ti samples showed relatively high corrosion resistance in 4 M HCl and 4 M H₂SO₄ solutions at 100 ± 5 °C. The passive current density values of the thermally oxidized samples were five orders of magnitude under the testing condition compared with that of the anodized sample. With the oxidation time prolonged, the passive current density decreased further to some extent.

Fluorescence spectroscopy is a common technique used to monitor early metallic corrosion. The fluorescence response characteristics of rhodamine-ethylenediamine toward Cu²⁺ have been studied using fluorescence and infrared spectroscopy. Fluorescence microscopy and electrochemical impedance spectroscopy were used to study the monitoring effect of rhodamine-ethylenediamine on the corrosion of copper relics protected by an epoxy coating. The results showed a strong fluorescent response and selectivity toward Cu²⁺ that existed using rhodamine-ethylenediamine. Early metallic corrosion of copper relics can be effectively monitored upon adding 0.8 wt % rhodamine-ethylenediamine to an epoxy coating. When the soaking time was increased, the fluorescence intensity of the fluorescent area on the coating became stronger. In addition, the area of the luminous coating reached ∼0.06 mm² and the area of corrosion under the protective coating was ∼0.008 mm², which was about 1/10 of the fluorescence area observed on the coating.

A chemical conversion coating on 5052 aluminum alloy was prepared by using K₂ZrF₆ and K₂TiF₆ as the main salts, KMnO₄ as the oxidant and NaF as the accelerant. The surface morphology, structure and composition were analyzed by SEM, EDS, FT–IR and XPS. The corrosion resistance of the conversion coating was studied by salt water immersion and polarization curve analysis. The influence of fluorosilane (FAS-17) surface modification on its antifouling property was also discussed. The results showed that the prepared conversion coating mainly consisted of AlF₃·3H₂O, Al₂O₃, MnO₂ and TiO₂, and exhibited good corrosion resistance. Its corrosion potential in 3.5 wt % NaCl solution was positively shifted about 590 mV and the corrosion current density was dropped from 1.10 to 0.48 μA cm⁻². By sealing treatment in NiF₂ solution, its corrosion resistance was further improved yielding a corrosion current density drop of 0.04 μA cm⁻². By fluorosilane (FAS-17) surface modification, the conversion coating became hydrophobic due to low-surface-energy groups such as CF₂ and CF₃, and the contact angle reached 136.8°. Moreover, by FAS-17 modification, the corrosion resistance was enhanced significantly and its corrosion rate decreased by about 25 times.