Abstract
The electrochemical properties and depassivation mechanism of Q355B steel passivation film in simulated concrete pore solutions with different Cl− concentrations were investigated by electrochemical tests integrated with nanoscale observation techniques. The results show that the thickness of the passivation film is 3–5 nm in the alkaline environment of the simulated concrete pore solution. The outer layer of the passivated film is primarily composed of Fe3+ oxides and Fe3+ hydroxides, and the inner layer is primarily composed of Fe2+ oxides, Fe3+ oxides, and Fe3+ hydroxides. At higher concentrations of Cl−, defects at the passivation film/solution interface increase, and cation vacancy deposition causes the passivation film to separate from the metal matrix. The passivation film in the deposited region stopped growing and eventually ruptured under internal stress.
Published Version
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