Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (04): 905-912.doi: 10.3866/PKU.WHXB20110336

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Inhibition of Ethyleneamine on the Pitting Corrosion of Rebar in a Synthetic Carbonated Concrete Pore Solution

DONG Ze-Hua, ZHU Tao, SHI Wei, GUO Xing-Peng   

  1. School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
  • Received:2010-09-26 Revised:2010-12-20 Published:2011-03-29
  • Contact: DONG Ze-Hua E-mail:zehua.dong@gmail.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50971064).

Abstract:

Tetraethylenepentamine (TEPA) was surveyed to show strong inhibition on pitting corrosion of Q345B carbon steel in a carbonated synthetic pore solution (SPS) by electrochemical noise (ECN), electrochemical impedance spectroscopy (EIS), and polarization curves. The pitting corrosion potential shifts positively with an increase in the TEPA concentration. ECN data show that the low content of TEPA can increase the nucleation rate of the metastable pits slightly and can effectively reduce their lifespan. The high content (0.10 mol·L-1) of TEPA accelerates the repassivation of metastable pitting and this is accompanied by an increase in noise resistance and a decrease in the nucleation rate and average pitting charge until the noise current transients disappear completely. Both the baseline current and the amplitude of the current transients decrease with an increase in the TEPA concentration, indicating that TEPA retards not only the pitting corrosion but also the general dissolution of the passive film. Micrographs show that the metastable pits mainly initiate and develop around the stable pits because of the induction of corrosion products, which causes the pitting cavity on carbon steel to grow generally in a planar rather than in a perpendicular direction.

Key words: Carbon steel, Pitting corrosion, Inhibitor, Concrete pore solution, Electrochemical noise

MSC2000: 

  • O646