Phosphate ions as corrosion inhibitors for reinforcement steel inchloride-rich environments

L. YOHAI; M. VAZQUEZ; M.B. VALCARCE

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2013 p. 88 - 96

0013-4686

tPhosphate ions were evaluated as corrosion inhibitors in solutions that simulate the composition ofthe pores in concrete contaminated with chloride ions. Cyclic voltammograms and potentiodynamicpolarization tests were complemented with micro-Raman spectroscopy and impedance spectroscopy tofollow the performance of this inhibitor. Long term performance involved weight loss evaluation. Chloridecontamination increases the accumulation of corrosion products on the metallic surface and promotespitting corrosion. In contrast, pitting is inhibited when phosphate ions are incorporated in a 1:1 phosphateto chloride molar ratio, even after a 90 days exposure. Micro Raman spectra clearly show the incorporationof phosphates to the passive film. Impedance spectroscopy results can be interpreted assuming a duplexsurface film formed in the presence of phosphates. In the conditions of this investigation, phosphate ionsbehave as mixed-type corrosion inhibitors, protecting steel against corrosion in chloride-contaminatedenvironments