The Effect of Triethanolamine Dodecylbenzene Sulfonate on Metastable Corrosion of 304 Stainless Steel

Reinforcing bars in concrete structures in marine environment are prone to pitting corrosion, which threatens the safety of engineering structures. In order to effectively mitigate the pitting corrosion of reinforcing bars, the electrochemical testing and atomic force microscopy are adopted, the effect of triethanolamine dodecylbenzene sulfonate (TDS) on metastable pitting behavior of 304 stainless steel (304 SS) in simulated concrete pore solutions (SCPS) with chlorine contamination was studied. The results show that the corrosion potential (E_corr) and breakdown potential (E_b) increased with the growth of the TDS concentrations. Statistical characteristics of metastable pits suggested that as the TDS concentrations increased in the SCPS, the parameters were all decreased. The Mott-Schottky tests exhibited that, although the donor density (N_D) diminished, the thickness of the space charge layer (W) increased with increasing TDS concentrations. Investigation results showed that TDS inhibited the sprouting and growth of metastable pits, and with greater TDS concentration, it becomes more difficult for metastable pits to transfer into stable pits in the SCPS, the generated stable passive film prevented the sprouting of pitting corrosion, It is recommended to use TDS with a concentration of not less than 3.364×10⁻⁴ mol/L in engineering, so that the sensitivity of passivation film of 304SS to chloride erosion is reduced.