Accelerated oxidation rate of chromium induced by sodium chloride

Shinata, Yutaka

doi:10.1007/bf00659274

Cited by 118 publications

(56 citation statements)

References 7 publications

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“…It is well known that the high-temperature corrosion of chromia-forming steels in an oxidising environment is accelerated by alkali chlorides and by high concentrations of water vapour [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The accelerated effect of water vapour has been shown to be connected to chromia evaporation in the form of CrO 2 (OH) 2 [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…The high corrosivity of alkali chlorides on stainless steel at elevated temperatures has been attributed to an ''active corrosion'' (chlorine cycle) mechanism [3][4][5][9][10][11][12] where alkali chlorides primarily are regarded as sources for molecular chlorine. However, recent reports show that the alkali cation also plays an important role in the corrosion attack [6,7,15].…”

Section: Introductionmentioning

confidence: 99%

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KCl-Induced Corrosion of the FeCrAl Alloy Kanthal ® AF at 600 °C and the Effect of H2O

et al. 2014

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The present study investigates the influence of H 2 O and KCl on the high-temperature corrosion of the FeCrAl alloy Kanthal Ò AF. Polished samples, with and without applied KCl, were exposed isothermally to O 2 or O 2 ? H 2 O at 600°C. The samples were investigated using TGA, XRD, SEM/EDX, AES and IC. It was found that KCl accelerates corrosion and that a rapidly growing iron, chromium-rich oxide forms in both environments. Chromate formation and alloy chlorination are shown to initiate the formation of non-protective oxide scales. In addition, aluminium nitrides form in the alloy substrate in both environments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

KCl-Induced Corrosion of the FeCrAl Alloy Kanthal ® AF at 600 °C and the Effect of H2O

et al. 2014

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“…Hence, the deposits formed on the superheater tubes are often rich in alkali chlorides. The corrosivity of alkali chlorides towards stainless steels at high temperature is well documented [9][10][11][12][13][14][15][16]. Hence, several attempts have been made to mitigate corrosion in the boilers by changing the chemistry of the fireside environment so as to suppress the formation of alkali chloride deposits [5,6,[17][18][19].…”

Section: Introductionmentioning

confidence: 99%

The Effects of KCl, K2SO4 and K2CO3 on the High Temperature Corrosion of a 304-Type Austenitic Stainless Steel

et al. 2011

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The oxidation of 304-type (Fe18Cr10Ni) austenitic stainless steel was investigated at 500 and 600°C in 5% O 2 ? 40% H 2 O. Prior to exposure the samples were sprayed with KCl, K 2 CO 3 or K 2 SO 4 , the amount of salt corresponding to 1.35 lmol K ? /cm 2 . For reference, salt-free samples were exposed in 5% O 2 ? 40% H 2 O and in 5% O 2 (N 2 was used as carrier gas). The oxidized samples were analyzed with SEM/EDX, XRD, IC and FIB. KCl and K 2 CO 3 strongly accelerate the corrosion of 304L while K 2 SO 4 has little influence on the corrosion rate and on the morphology of the corroded surface. KCl and K 2 CO 3 react with the chromium-rich oxide on the sample surface, forming K 2 CrO 4 . The resulting chromium depletion of the protective oxide causes rapid oxidation and the formation of a thick duplex scale consisting of an outer hematite layer and a inner layer made up of FeCrNi spinel-type oxide. The differences in the corrosivity of the three salts are directly connected to their ability to form chromate on the surface and, hence, to the relative stability of the corresponding leaving groups (HCl, CO 2 and SO 3 ).

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“…Para poder aumentar, en el futuro, la temperatura del vapor de una forma significativa (en un primer paso, hasta 600º C) y, por lo tanto, la eficiencia de las plantas, se están realizando muchas investigaciones para mejorar la resistencia de los sobrecalentadores. Se ha demostrado [69][70][71][72][73][74][75] que el cromo no es un elemento efectivo para mejorar la resistencia a la corrosión de aleaciones en base hierro y níquel, en medios de sales alcalinas cloradas, cuando las temperaturas están próximas a 600º C. La explicación general se debe a que el Cr 2 O 3 (s) tiene como cromato una alta solubilidad en mezclas fundidas de KCl-K 2 SO 4 . A partir de estos resultados, existen dos estrategias desde el punto de vista metalúrgico: la primera, es cambiar la composición de los aleantes, de una forma sustancial y, la segunda, modificar la superficie mediante recubrimientos que formen capas protectoras.…”

Section: úLtimos Estudios Realizados Y Perspectivas Para Investigaciounclassified

Review about corrosion of superheaters tubes in biomass plants

Labari¹,

Fernández-Carrasquilla²

2006

Rev. metal.

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ResumenEn el diseño de plantas de biomasa es muy importante tener en cuenta la temperatura del vapor para no tener problemas de corrosión. Esto, es debido al alto contenido de potasio y cloro que tienen la mayoría de los biocombustibles y, en especial, la paja de cereal. El objetivo de esta revisión es condensar el conocimiento actual sobre la corrosión de los sobrecalentadores a altas temperaturas provocada por compuestos clorados en plantas de biomasa. El cloro puede causar corrosión acelerada debido a la pérdida de metal del sobrecalentador, ataque interno y formación de capas de óxidos no adherentes. Los problemas de corrosión más severos en una caldera de biomasa se producen en los depósi-tos formados sobre los tubos sobrecalentadores. En la primera parte de esta revisión, se describen los mecanismos de corrosión propuestos en función de las condiciones de trabajo predominantes en la caldera. La segunda parte, se centra en revisar los estudios realizados para comprobar el comportamiento de los materiales mediante ensayos realizados en la caldera y en el laboratorio. En primer lugar, se describen las investigaciones realizadas sobre aleaciones convencionales y después las realizadas sobre las aleaciones desarrolladas en los últimos años y recubrimientos. Palabras claveCorrosión a altas temperaturas. Corrosión por depósitos. Corrosión gaseosa. Biomasa. Sobrecalentadores. Review about corrosion of superheaters tubes in biomass plants AbstractThe design of new biomass-fired power plants with increased steam temperature raises concerns of high-temperature corrosion. The high potassium and chlorine contents in many biomasses, specially in wheat straw, are potentially harmful elements with regard to corrosion. Chlorine may cause accelerated corrosion resulting in increased oxidation, metal wastage, internal attack, void formations, and loose non-adherent scales. The most severe corrosion problems in biomass-fired systems are expected to occur due to Cl-rich deposits formed on superheater tubes. In the first part of this revision the corrosion mechanism proposed are described in function of the conditions and compounds involved. The second part is focused on the behaviour of the materials tested so far in the boiler and in the laboratory. First the traditional commercial alloys are studied and secondly the new alloys and the coatings.

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Accelerated oxidation rate of chromium induced by sodium chloride

Cited by 118 publications

References 7 publications

KCl-Induced Corrosion of the FeCrAl Alloy Kanthal ® AF at 600 °C and the Effect of H2O

KCl-Induced Corrosion of the FeCrAl Alloy Kanthal ® AF at 600 °C and the Effect of H2O

The Effects of KCl, K2SO4 and K2CO3 on the High Temperature Corrosion of a 304-Type Austenitic Stainless Steel

Review about corrosion of superheaters tubes in biomass plants

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