Red clay soils show especially corrosive towards metallic materials, but no satisfactory interpretation exists to explain the phenomenon. Soil Fe oxides (goethite, hematite, etc.) appear to play a key role in soil corrosion by functioning as a cathodic depolarizer. A series of experiments were therefore conducted to evaluate the effect of Fe oxides on corrosion of pipeline steel in a red clay soil. The results indicate that corrosivity of the red clay soil greatly relieves after Fe oxides are removed from the soil. In the case of periodic wetting and drying of the soil, the Fe oxides act as an accumulator of reducible substances and an autocatalytic reaction process involves in corrosion process of carbon steel. The charge-transfer resistance is significantly higher in Fe oxides eliminated soils than that in the original red soil. After 60 day exposure, the steel surface undergoes severe uniform corrosion attack over the entire surface in the red soil, whereas most of the surface remains intact in the waterlogged soil and in the DCB(dithionite-citrate buffer)-treated soil. A Fe oxide-catalyzed kinetic mechanism is proposed to clarify high corrosivity of red clay soils.
Role of Fe oxides in corrosion of pipeline steel in a red clay soil
Die Rolle von Eisenoxiden bei der Korrosion von Rohrstahl in roter Lehmerde
Corrosion Science ; 80 ; 309-317
2014
9 Seiten, 11 Bilder, 6 Tabellen, 44 Quellen
Article (Journal)
English
Rohrstahl , Lehmboden , Eisenoxid , Korrosionsgeschwindigkeit , Goethit , Hämatit , Depolarisation , kathodische Polarisation , aggressive Substanz , chemische Aufbereitung , China , Oberflächenbeschaffenheit , Röntgenbeugung , Korrosionsmechanismus , Polarisationskurve , elektrochemische Impedanzspektrometrie , Langzeitverhalten
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