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Effect of aluminum Tripolyphosphate on pitting initiation on carbon steel in chloride contaminated concrete pore solution

Xiangyu Lu (Hohai University, Nanjing, China)
Leyuan Zhang (Hohai University, Nanjing, China)
Xingguo Feng (Hohai University, Nanjing, China)
D. Chen (Hohai University, Nanjing, China)
Yu Zuo (Beijing University of Chemical Technology, Beijing, China)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Article publication date: 22 August 2019

Issue publication date: 22 August 2019

Abstract

Purpose

Aluminum tripolyphosphate was used as a corrosion inhibitor in a simulated concrete pore solution. For studies of the inhibition mechanism of aluminum tripolyphosphate on the carbon steel, its influence on the pitting initiation on the carbon steel in a Cl containing pore solution were investigated.

Design/methodology/approach

Potentiodynamic polarization curves, Mott–Schottky plots and potentiostatic polarization of the carbon steel in the pore solution with different content of aluminum tripolyphosphate were measured, as well as the optical micrographs of pitting on the carbon steel was observed.

Findings

The metastable pitting potential and the stable pitting potential increased, while the donor density and the flat band potential decreased with the concentration of aluminum tripolyphosphate in solution. Furthermore, the initiation of pitting was suppressed, as well as the transition from metastable to stable pitting was hindered by the aluminum tripolyphosphate. The scale parameter (a), in the extreme distribution of the maximum current peak, could be used to predict the transition from metastable to stable pitting.

Originality/value

The inhibition mechanism of aluminum tripolyphosphate on carbon steel in pore solution was revealed. It suppresses the initiation of pitting and hinders the transition from metastable to stable pitting. Furthermore, a parameter defined as the scale parameter (a) in the extreme distribution of the maximum current peak was introduced to predict the transition from metastable to stable pitting.

Keywords

Acknowledgements

The authors are grateful to the National Natural Science Foundation of China (51601074), the Fundamental Research Funds for the Central Universities (2018B07214, 2018B56714) and the Opening Project of State Key Laboratory of Green Building Materials.

Citation

Lu, X., Zhang, L., Feng, X., Chen, D. and Zuo, Y. (2019), "Effect of aluminum Tripolyphosphate on pitting initiation on carbon steel in chloride contaminated concrete pore solution", Anti-Corrosion Methods and Materials, Vol. 66 No. 5, pp. 603-612. https://doi.org/10.1108/ACMM-03-2019-2094

Publisher

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Emerald Publishing Limited

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