Temperature dependence of the electrochemical corrosion characteristics of carbon steel in a salty soil |
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Authors: | X H Nie X G Li C W Du Y F Cheng |
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Affiliation: | (1) Materials Science and Engineering School, University of Science and Technology Beijing, Beijing, 100083, China;(2) Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB, Canada, T2N 1N4 |
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Abstract: | The electrochemical corrosion characteristics of carbon steel in a salty soil at different temperatures were studied by measurements
and analyses of potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy.
The results showed that the mass-transfer of dissolved oxygen plays an essential role in carbon steel corrosion, and the whole
corrosion process is mix-controlled by both activation and mass-transfer steps. Passivity can be developed on carbon steel
in the soil at low temperatures. With the increase of temperature, the passive current density increases and the passive potential
range decreases. When temperature is elevated to a certain value, 50 °C in this system, passivity cannot be maintained and
the steel is dominated by an active dissolution status. Anodic Tafel slope decreases continuously with the increase in temperature,
which is mainly due to the enhanced electrode reaction rate at an elevated temperature. Simultaneously, cathodic Tafel slope
increases with temperature continuously due to the decrease of the solubility of dissolved oxygen in soil. Since the diffusion
activation energy is generally much smaller than the reaction activation energy, the effect of temperature on diffusion is
far less than that on electrode reaction rate. |
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Keywords: | Corrosion Carbon steel Salty soil Electrochemical measurements |
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