Insights into the corrosion mechanism and electrochemical properties of the rust layer evolution for weathering steel with various Cl<sup>−</sup> deposition in the simulated atmosphere
Qiang Yu, Wangyue Dong, Xiaoyu Yang, Qingfeng Wang, Fucheng Zhang
Abstract
Abstract This study aims to make clear the effect of various Cl − deposition conditions on the changes of corrosion mechanism and electrochemical properties of the rust layer for weathering steel. The results indicate that the corrosion rate in presence of low Cl − deposition is divided into three stages: sharp increase stage, rapid decrease stage and tending to be stable stage. While, the high Cl − deposition process is divided into two stages: sharp increase stage and decrease stage. The increased of Cl − deposition increase the contents of the γ -FeOOH and β -FeOOH and decrease the contents of the α -FeOOH, and then to reduce the corrosion resistance. For the initial corrosion cycles, the increased of Cl − deposition influence the oxygen supply, resulting in spatial heterogeneity of the potential distribution to promote the corrosion reaction. As the prolonged corrosion cycles, the weathering steel of low Cl − deposition forms a protective rust layer to make the potential distribution become relatively uniform to reduce the corrosion rate, while the weathering steel of high Cl − deposition of the potential distribution is more unevenly distributed with distinct low and high potential zones to promote corrosion reaction.