Physicochemical performance of FeCO 3 films influenced by anions

• Published in: RSC advances Vol. 5; no. 26; pp. 20302 - 20308
• Main Authors: Ren, Chengqiang, Wang, Wanguo, Jin, Xing, Liu, Li, Shi, Taihe
• Format: Journal Article
• Language: English
• Published: 2015
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C4RA14313B

The corrosion film plays an important role in the further electrochemical processes of steel in CO 2 corrosion. Thus, the physicochemical performance of an FeCO 3 film was investigated using the Mott–Schottky electrochemical technique, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The performance of the FeCO 3 film was dependent on the aqueous solution. In 0.5 mol L −1 NaHCO 3 solution, an n-type semiconducting behavior was found for the FeCO 3 film. The dense microstructure and lower interstitial cation or anion vacancy doping was in favor of strong corrosion resistance of the film. On the contrary, a p-type semiconducting behavior of the FeCO 3 film was exhibited in both 0.5 mol L −1 NaCl solution and 0.5 mol L −1 Na 2 SO 4 solution. Higher cation vacancy doping was found, and the integrity of the microstructure was damaged, which decreased the transfer resistance of electron and mass. As a result, the protective ability of the FeCO 3 film was decreased. The physicochemical mechanism for the semiconducting properties of the FeCO 3 film was explained using the Point Defect Model (PDM).