Preparation of tannic acid-based conversion coating and corrosion protection performances for steel in chlorinated simulated concrete pore solution

A tannic acid-based conversion coating (TACC) has been developed on steel surface to protect carbon steel within a chlorinated simulated concrete pore solution (Cl-SCPS). The morphology, composition, and protective efficacy of TACC for carbon steel are examined through using SEM, FT-IR, Raman, EDS, XPS, and electrochemical measurements. The findings reveal that TACC significantly enhances the corrosion resistance of carbon steel. The TACC with a 2-min treatment showcases the optimal corrosion protection for steel, sustaining a protection efficiency of 99.84 % even after a 7-day exposure period. As the samples are exposed to the Cl-SCPS, the passivation products formed serve to fill the pores in the TACC, thereby enhancing its compactness and protective capabilities.