pH-Responsive Containers Based on Modified Hollow TiO₂for Active and Passive Protection of Carbon Steel

Abstract

In this study, TiO 2 containers with an empty core and a mesoporous shell were successfully synthesized via hydrothermal reaction. The as-prepared TiO 2 was used as carrier to load the corrosion inhibitor 2-mercaptobenzimidazole (MBI). The outer shell of inhibitor-loaded containers was modified by a SiO 2 film, which was obtained from hydrolysis of tetraethyl orthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES). The structure of the TiO 2 containers was studied using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR) spectrometry. The release behavior of the corrosion inhibitor was investigated using UV-visible spectroscopy. The corrosion protection performance of the water-based epoxy coating with modified TiO 2 containers was studied by using electrochemical impedance spectroscopy (EIS) and a scanning Kelvin probe (SKP). The coating with modified TiO 2 containers demonstrated enhanced film barrier properties compared with blank coating. Results obtained from SKP measurements confirmed active corrosion protection performance of the studied TiO 2 containers.

Zn-Co-CeO2 vs. Zn-Co Coatings: Effect of CeO2 Sol in the Enhancement of the Corrosion Performance of Electrodeposited Composite Coatings

“…SKP measures the Volta potential difference between the working electrode (examined coating) and reference electrode (SKP probe). Measured Volta potential difference changes linearly with corrosion potential (E corr = ψ re f coating + const) [21]. The SKP tip is made of Ni-Cr alloy.…”

“…As a consequence, local electrochemical processes in microdefects cannot be separately investigated. The scanning Kelvin probe technique allows in-situ determination of localized potential changes on the coating surface [21,28,29]. SKP measures the Volta potential between the device's tip and working electrode (coating).…”

“…SKP measures the Volta potential between the device's tip and working electrode (coating). The determined Volta potential is proportional to the corrosion potential [21]. The Volta potential surface distribution of the Zn-Co, Zn-Co-CeO 2 (CeO 2 powder) and Zn-Co-CeO 2 (CeO 2 sol) coatings during 24 h in the device chamber is presented in Figures 16-18, respectively.…”

Preparation of Sol-Gel Derived Anticorrosive Coating on Q235 Carbon Steel Substrate with Long-Term Corrosion Prevention Durability

“…To further elaborate on the electrochemical properties of both coating structures, the EIS spectra after different immersion times were fitted using the equivalent circuits depicted in Figure 12, which are the widely used equivalent circuit designs in the literature [5,38,42,43,44]. Here, constant phase elements (CPEs) instead of ideal capacitors were used to better fit the experimental results, and the impedance of a CPE is defined by Z CPE = Y 0 −1 (jw) − n , where w is the angular frequency, and Y 0 and n represent the calculated parameters for the CPEs [42].…”

“…For the one-layer coating, the R c and R ct values generally represent the electrolyte penetration capability of the coatings and corrosion resistance behaviors at the coating/metal interface, respectively [44]. As shown in Table 2, both R c and R ct values dropped drastically with elapsed immersion time, indicative of rapid deterioration of the coating film and its corrosion resistance.…”