Synergistic Inhibition Effect of Sodium Tungstate and Hexamethylene Tetramine on Reinforcing Steel Corrosion

• Published in: Journal of the Electrochemical Society 2015-01, Vol.162 (10), p.C555-C562
• Main Authors: Gao, Ying-Bo, Hu, Juan, Zuo, Juan, Liu, Qing, Zhang, Hui, Dong, Shi-Gang, Du, Rong-Gui, Lin, Chang-Jian
• Format: Article
• Language: English
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/2.0641510jes

Sodium tungstate (Na2WO4) and hexamethylene tetramine (HMTA) are both eco-friendly corrosion inhibitors. In this work, their synergistic corrosion inhibition effects on reinforcing steel in the simulated polluted concrete pore solution containing Cl− were studied by electrochemical techniques including electrochemical impedance spectroscopy and potentiodynamic anodic polarization curve measurements. The morphologies and compositions of the steel surface were characterized by Electron Micro-Probe Analyzer, X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that the serious steel corrosion took place in the solution with pH 11.00 and 0.5 M NaCl. However, a stable passive region occurred in the anodic polarization curve of the steel and its corrosion current density decreased dramatically after addition of a mixed inhibitor with 0.01 M Na2WO4 and 0.01 M HMTA to the solution. The inhibition efficiency of the mixed inhibitor reached 97.1%. The surface analyses revealed that a protective composite film was formed on the steel in the solution with the mixed inhibitor, which indicated that the mixed inhibitor had a synergistic inhibition effect on the steel corrosion. Our study also indicated that the mixed inhibitor could effectively control corrosion of the reinforcing steel in cement mortar.