Inhibiting Steel Corrosion in Simulated Concrete with Low Phosphate to Chloride Ratios

L. YOHAI; W. SCHREINER; M. B. VALCARCE; M.VÁZQUEZ

JOURNAL OF THE ELECTROCHEMICAL SOCIETY

ELECTROCHEMICAL SOC INC

Año: 2016 vol. 163 p. 1 - 9

0013-4651

Phosphate ions are studied as corrosion inhibitors in pore simulating solutions highly contaminated with chloride ions. The investigationaims at understanding the role of phosphates in the corrosion inhibition mechanism, employing potentiodynamic polarizationtests, micro-Raman spectroscopy, impedance spectroscopy, X-ray photo electronic spectroscopy (XPS) and weight loss tests. Twoinhibitor/chloride ratios were assessed, [PO43−]/[Cl−] = 0.2 and 0.6. When [PO43−]/[Cl−] = 0.6, pitting is inhibited, even after90 days exposure. [PO43−]/[Cl−] = 0.2 only delayed the onset of localized attack. XPS showed that phosphates incorporate to thesurface film. Phosphate ions behaved asmixed-type corrosion inhibitors. The results are interpreted by the participation of phosphatesin the duplex passive film being formed on carbon steel.