Einfluß von Chloriden auf die Oxidation des 2¼ Cr‐1 Mo‐Stahls

Reese, E.; Grabke, H. J.

doi:10.1002/maco.19920431202

Cited by 60 publications

(33 citation statements)

References 14 publications

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“…Since gaseous reaction products, CrCl 2 and CO, are formed, holes are left in the metal matrix and internal oxidation follows. Other carbides such as Mo 6 C, TiC and NbC are more corrosion resistant than the alloy matrix and stay uncorroded. Accordingly, presence or formation of chromium carbides should be avoided in alloys applied in oxidizing-chloridizing environments.…”

Section: Discussionmentioning

confidence: 99%

“…The morphology of the scale indicates that the mechanism of the scale growth is the same: formation of a multilayer by active oxidation, repeated cracking and spalling of the layers and formation of oxide bubbles over cracks. The metal phase contains intermetallic compounds Cr 6 Fe 18 Ti 5 as precipitates and they are preferentially attacked, due to the highly negative free energies of Ti-chlorides formation.…”

Section: 3ternary Alloys Fe-15% Cr-mmentioning

confidence: 99%

“…In a detailed study of effects of chlorides on the oxidation of a low alloy steel it was shown that the outward diffusion of the gaseous FeCl 2 (g) is rate determining for this corrosion process [4][5] . 'Active oxidation' also takes place on high alloy steels [5][6] under formation of voluminous non protective scales. These steels also show a typical grain boundary attack under oxidizing and chloridizing conditions, i.e.…”

Section: Introduction: Reactions and Mechanismsmentioning

confidence: 99%

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Role of alloying elements and carbides in the chlorine-induced corrosion of steels and alloys

2004

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The high temperature corrosion of steels and Ni-base alloys in oxidizing and chloridizing environments is of practical interest in relation to problems in waste incineration plants and power plants using Cl containing fuels. The behaviour of the most important alloying elements Fe, Cr, Ni, Mo, Mn, Si, Al upon corrosion in an oxidizing and chloridizing atmosphere was elucidated: the reactions and kinetics can be largely understood on the base of thermodynamic data, i.e. free energy of chloride formation, vapor pressure of the chlorides and oxygen pressure p O2 needed for the conversion chlorides → oxides.The mechanism is described by 'active oxidation', comprising inward penetration of chlorine into the scale, formation of chlorides at the oxide/metal interface, evaporation of the chlorides and conversion of the evaporating chlorides into oxides, which occurs in more or less distance from the surface (depending on p O2 ). This process leads to loose, fragile, multilayered oxides which are unprotective (therefore: active oxidation). Fe and Cr are rapidly transferred into such scale, Ni and Mo are relatively resistant.In many cases, the grain boundaries of the materials are strongly attacked, this is due to a susceptibility of chromium carbides to chloridation. In contrast the carbides Mo 2 C, TiC and NbC are less attacked than the matrix.Alloys on the basis Fe-Cr-Si proved to be rather resistant, and the alloying elements Ni and Mo clearly retard the attack in an oxidizing and chloridizing environment.

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Section: Discussionmentioning

confidence: 99%

Section: 3ternary Alloys Fe-15% Cr-mmentioning

confidence: 99%

Section: Introduction: Reactions and Mechanismsmentioning

confidence: 99%

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Role of alloying elements and carbides in the chlorine-induced corrosion of steels and alloys

2004

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“…Metal oxides can be dissolved in molten NaCl-KCl also by acidic and basic dissolution. The effect of solid chlorides like KCl, NaCl, MgCl 2 and CaCl 2 on corrosion of alloy steels has been investigated by Reese and Grabke [6,7]. Their experiments in He -O 2 and He -O 2 -SO 2 atmospheres at 500 and 700 8C have shown that the salt reacts with the oxide scale of the pre-oxidised sample forming ferrate or chromate and releasing chlorine.…”

Section: Introductionmentioning

confidence: 99%

“…As chlorine is not consumed in this process, it plays a catalytic role. Reese and Grabke [6] have shown by thermogravimetric studies that evaporation of FeCl 2 from the metal-scale interface is the rate determining step in 'active oxidation'.…”

Section: Introductionmentioning

confidence: 99%

Influence of gas phase composition on the kinetics of chloride melt induced corrosion of pure iron (EU-project OPTICORR)

Ruh¹,

Spiegel

2006

Materials and Corrosion

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Heat exchanger tubes in waste-fired boilers are usually attacked by aggressive gases like oxygen, HCl and water vapour as well as by solid and molten salts. Especially if the salt deposit is molten, these compounds cause acceleration of the corrosion process. This study focuses on kinetic investigations on the influence of gas phase composition (O 2 , HCl and H 2 O) on the chloride melt induced corrosion of Fe.Thermogravimetric (TG) tests were conducted on Fe covered by a 50 mol.% KCl/50 mol.% ZnCl 2 -salt mixture at T ¼ 320 8C, first in an Ar -O 2 -atmosphere. In these experiments the amounts of salt deposit (15 and 30 mg/cm 2 ) and oxygen (4 -16 vol.%) were varied to investigate their influences on corrosion kinetics. The TG curves show three kinetic stages, i.e. an incubation phase, a linear stage and a logarithmic/parabolic stage [1]. Further it could be shown that the duration of the incubation phase and the slope of the linear stage depend on the amount of the salt deposit as well as on the oxygen partial pressure (p(O 2 )). The incubation time increases with increasing amount of salt deposit and decreases with increasing p(O 2 ).Experiments that were carried out in an Ar -O 2 -HCl atmosphere (500 -2000 vppm HCl, 4 -16 vol.% O 2 ) yield enhanced mass gain in comparison to TG tests without HCl. In atmospheres containing at least 1000 vppm HCl corrosion starts immediately without going through an incubation phase following a linear rate law. In the next stage the TG curve follows a rate law that is either parabolic or logarithmic. At higher amounts of HCl (2000 vppm, 8 vol.% O 2 ) the TG curve shows a relative mass loss after about 55 h of corrosion indicating an evaporation of iron chloride. This phenomenon was also observed at 1000 vppm HCl and 16 vol.% O 2 but not in the other experiments presented in this study.Experiments carried out in Ar -O 2 -H 2 O are discussed also. In general the TG curves show lower mass gains after some hours of corrosion in comparison to TG tests without H 2 O but at the beginning a shortened incubation phase is evident.

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Salt melt induced corrosion of metallic materials in waste incineration plants

Spiegel

1999

Materials and Corrosion

139

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Einfluß von Chloriden auf die Oxidation des 2¼ Cr‐1 Mo‐Stahls

Cited by 60 publications

References 14 publications

Role of alloying elements and carbides in the chlorine-induced corrosion of steels and alloys

Role of alloying elements and carbides in the chlorine-induced corrosion of steels and alloys

Influence of gas phase composition on the kinetics of chloride melt induced corrosion of pure iron (EU-project OPTICORR)

Salt melt induced corrosion of metallic materials in waste incineration plants

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