Effects of the Different Solid Deposits on the Corrosion Behavior of Pure Fe in Water Vapor at 500°C

Yanbing Tang; Xinwang Shen; Zhihong Liu; Ying Li

doi:10.1155/2020/6280725

Effects of the Different Solid Deposits on the Corrosion Behavior of Pure Fe in Water Vapor at 500°C

Scanning. 2020 Sep 11:2020:6280725. doi: 10.1155/2020/6280725. eCollection 2020.

Authors

Yanbing Tang^{1

2}, Xinwang Shen³, Zhihong Liu³, Ying Li¹

Affiliations

¹ Institute of Metal Research, Chinese Academy of Sciences, 110016 Shenyang, China.
² Marine Equipment and Technology Institute, Jiangsu University of Science and Technology, 212003 Zhenjiang, China.
³ School of Materials Science and Technology, Jiangsu University of Science and Technology, 212003 Zhenjiang, China.

Abstract

A comprehensive corrosion investigation of pure Fe in an environment of solid sodium salt deposit (i.e., NaCl or Na₂SO₄) with mixtures of H₂O and O₂ at 500°C was conducted by mass gain measurement, X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results showed that corrosion rates were accelerated with solid NaCl or Na₂SO₄ deposit due to their reaction with the formed protective scale of Fe₂O₃ and subsequently resulted in its breakdown. The corrosion rate of pure Fe with solid NaCl is higher than that with solid Na₂SO₄ because of the lower activation energy (E _a) for chemical reaction of Fe in solid NaCl+H₂O+O₂ (i.e., 140.5 kJ/mol) than that in solid Na₂SO₄+H₂O+O₂ (i.e., 200.9 kJ/mol). Notably, the electrochemical corrosion rate of pure Fe with solid NaCl deposit, 1.16 × 10^-4 A/cm², was a little lower than that with solid Na₂SO₄ deposit.