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Passivation Characteristics of Alloy Corrosion-Resistant Steel Cr10Mo1 in Simulating Concrete Pore Solutions: Combination Effects of pH and Chloride

by Zhiyong Ai 1,2, Wei Sun 1,2, Jinyang Jiang 1,2,*, Dan Song 1,2,3, Han Ma 4, Jianchun Zhang 4 and Danqian Wang 1,2
1
School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu, China
2
Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu, China
3
College of Mechanics and Materials, Hohai University, Nanjing 210098, Jiangsu, China
4
Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu, China
*
Author to whom correspondence should be addressed.
Academic Editors: Peter J. Uggowitzer and Daniel J. Blackwood
Materials 2016, 9(9), 749; https://doi.org/10.3390/ma9090749
Received: 2 July 2016 / Revised: 17 August 2016 / Accepted: 29 August 2016 / Published: 1 September 2016
The electrochemical behaviour for passivation of new alloy corrosion-resistant steel Cr10Mo1 immersed in alkaline solutions with different pH values (13.3, 12.0, 10.5, and 9.0) and chloride contents (0.2 M and 1.0 M), was investigated by various electrochemical techniques: linear polarization resistance, electrochemical impedance spectroscopy and capacitance measurements. The chemical composition and structure of passive films were determined by XPS. The morphological features and surface composition of the immersed steel were evaluated by SEM together with EDS chemical analysis. The results evidence that pH plays an important role in the passivation of the corrosion-resistant steel and the effect is highly dependent upon the chloride contents. In solutions with low chloride (0.2 M), the corrosion-resistant steel has notably enhanced passivity with pH falling from 13.3 to 9.0, but does conversely when in presence of high chloride (1.0 M). The passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer enriched in Fe oxides and hydroxides, and an inner layer, rich in Cr species. The film composition varies with pH values and chloride contents. As the pH drops, more Cr oxides are enriched in the film while Fe oxides gradually decompose. Increasing chloride promotes Cr oxides and Fe oxides to transform into their hydroxides with little protection, and this is more significant at lower pH (10.5 and 9.0). These changes annotate passivation characteristics of the corrosion-resistant steel in the solutions of different electrolyte. View Full-Text
Keywords: passivation; pH; chloride; corrosion-resistant steel; film composition passivation; pH; chloride; corrosion-resistant steel; film composition
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MDPI and ACS Style

Ai, Z.; Sun, W.; Jiang, J.; Song, D.; Ma, H.; Zhang, J.; Wang, D. Passivation Characteristics of Alloy Corrosion-Resistant Steel Cr10Mo1 in Simulating Concrete Pore Solutions: Combination Effects of pH and Chloride. Materials 2016, 9, 749.

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