Influence of temperature and thiosulfate on the corrosion behavior of steel in chloride solutions saturated in CO@d2

• Published in: Materials in engineering Vol. 30; no. 9; pp. 3420 - 3427
• Main Author: Ezuber, H M
• Format: Journal Article
• Language: English
• Published: 01.10.2009
• ISSN: 0261-3069
• DOI: 10.1016/j.matdes.2009.03.028

The corrosion resistance of mild steel in environments of 1M NaCl solutions saturated in CO@d2 was investigated in the absence and presence of different concentrations of thiosulfate (0.01-1M Na@d2S@d2O@d3), one of the main sulfide oxidation product, at 22 and 50@uoC. Polarization measurements and immersion tests revealed remarkable increase in the chloride corrosion rate in the presence of dissolved CO@d2 species and/or thiosulfate ions. Solutions containing Cl@u--S@d2O@d3@u2@u--dissolved CO@d2 species exhibited higher corrosion attack than those conducted in Cl@u--S@d2O@d3@u2@u- or Cl@u--dissolved CO@d2 solutions and is increased with increasing thiosulfate concentration. The room temperature results were compared to those measured at 50@uoC. Similar polarization type behavior was obtained with higher corrosion rates for the higher solution temperature. Although the presence of thiosulfate and/or dissolved CO@d2 species activated the steel anodic/cathodic polarization curves in chloride solutions, this effect was more pronounced on the cathodic side and in the presence of dissolved CO@d2 species. The cathodic current density showed substantial displacement to more active values in the presence of thiosulfate and/or dissolved CO@d2 and increased with increasing thiosulfate concentration.