Crevice Corrosion of Titanium in High Temperature-Concentrated Chloride Environments |
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Authors: | Mohammed I Abdulsalam |
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Affiliation: | (1) Department of Chemical and Materials Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, 21589, Saudi Arabia |
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Abstract: | Crevice corrosion of titanium is activated in concentrated chloride media at 100 °C. This was possible only with the tightest
gap (0.005 cm) between Ti-Ti surfaces. No crevice corrosion was observed with greater gap dimensions. The design of the crevice
led to the occurrence of two concentric circular rings of corroded areas, with many pits on them. After potentiostating in
the passive region for 5 h in 25% NaCl (pH = 4.7)—where hydrogen evolution is thermodynamically prohibited—hydrogen gas bubbles
were observed to egress out of the crevice mouth during ongoing crevice corrosion. This indicates that hydrogen evolution
occurs within the crevice. The results are compatible with the occurrence of gradually increasing ohmic potential shift and
localized acidification in the crevice electrolyte as judged by the measured gradual increase of the crevice corrosion current.
The high acidity of the bulk electrolyte does not seem to be sufficient or even a necessary condition for crevice corrosion
to occur. |
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Keywords: | acidification chloride crevice corrosion high temperature hydrogen bubbles ohmic potential drop titanium |
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