Electrochemical behavior and corrosion products of Cr-modified reinforcing steels in saturated Ca(OH)2 solution with chlorides

In this paper, the evolution of natural passivation and chloride-induced corrosion, pitting corrosion resistance and corrosion products composition of two Cr-modified reinforcing steels and the low-carbon (LC) reinforcing steel in saturated Ca(OH)(2) solution with chlorides were evaluated by a combined electrochemical measurements (E-corr, LPR, EIS, CV and CPP) and surface analysis techniques (XPS, Raman, FT-IR, and SEM/EDS). The passive films enriched with Cr oxides/hydroxides were formed for Cr-modified steels, resulting in higher passivation capability and corrosion resistance than those of LC steel at natural passivation stage and chloride-induced corrosion stage, respectively. Also, it was confirmed that after chloride exposure, beta-FeOOH was widely identified on the outer surface of LC steel, while gamma-FeOOH was mainly pronounced for Cr-modified steels. Moreover, compared with LC steel, higher pitting corrosion resistance was evident for Cr-modified steels with various chloride concentrations. Finally, the mechanisms of natural passivation and chloride-induced pitting corrosion for steels in saturated Ca(OH)(2) solution were proposed.