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KCl-Induced Corrosion of a 304-type Austenitic Stainless Steel in O-2 and in O-2 + H2O Environment: The Influence of Temperature

Jesper Pettersson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Jan-Erik Svensson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Lars-Gunnar Johansson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi)
Oxidation of Metals (0030-770X). Vol. 72 (2009), 3-4, p. 159-177.
[Artikel, refereegranskad vetenskaplig]

The oxidation of the 304-type (Fe18Cr10Ni) austenitic stainless steel was investigated in the temperature range 400-600 A degrees C in 5% O-2 and 5% O-2 + 40% H2O. Exposure time was up to 1 week. Prior to exposure, the polished samples were coated with 0.1 mg/cm(2) KCl. Uncoated samples were also exposed and used as references. The oxidized samples were analyzed by gravimetry and by ESEM/EDX, XRD, IC and AES. The results show that KCl is strongly corrosive. Corrosion is initiated by the reaction of KCl with the chromia-containing oxide that normally forms a protective layer on the alloy. This reaction produces potassium chromate particles, leaving a chromium-depleted oxide on the alloy surface. At 500 and 600 A degrees C this results in rapid oxidation, resulting in the formation of a thick scale consisting of a mixture of hematite, spinel oxide ((Fe,Cr,Ni)(3)O-4) and K2CrO4. The thick scale is poorly protective and permeable to e.g. chloride ions. The KCl-induced corrosion of alloy 304L in dry O-2 and in an O-2 + H2O mixture increases strongly with temperature in the range 400-600 A degrees C. The strong temperature dependence is explained partly by the temperature dependence of the chromate-formation reaction and partly by the ability of the chromium-depleted oxide to protect the alloy at low temperature. At 400 A degrees C, the oxide was still protective after 168 h.

Nyckelord: Oxidation, KCl, Deposit, Breakaway Corrosion, 304L, oxide hydroxide evaporation, water-vapor, oxidation, chloride, 600-degrees-c, 304l



Denna post skapades 2010-02-26. Senast ändrad 2014-11-10.
CPL Pubid: 115565

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)

Ämnesområden

Metallurgisk process- och produktionsteknik

Chalmers infrastruktur