A laboratory study of the corrosion behaviour of Alloys exposed in a non‐equilibrated coal gasification atmosphere at 600°C

Norton, J. F.; Levi, T.P.

doi:10.1002/maco.19950460504

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…Alumina scales are protective in sulphidising environments at intermediate temperatures, too [20]. At 600 and 650 "C the rate of alumina formation is, however, very low and other reactions, like the formation of nickel sulphides or sulphates may occur, until a continuous alumina scale is formed.…”

Section: Discussionmentioning

confidence: 99%

“…Such improvements of sulphidation resistance in H2S atmospheres were also found in iron aluminides, where the corrosion rate decreased dramatically, when 10% chromium were added [ 171. As Norton and Levy pointed out there seems to be a sensitive balance between the competing reactions of alumina-formation, chromia-formation and sulphidation during the corrosion of aluminaforming alloys at low temperatures in sulphidising environments [20].…”

Section: Discussionmentioning

confidence: 99%

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High temperature corrosion behaviour of a new Ni‐30Fe‐10Al‐Cr‐Alloy

Klöwer¹,

Sauthoff

1997

Materials & Corrosion

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Dedicated to Dr. U. Heubner on the occasion of his 65th birthdayThe high temperature corrosion behaviour of a new duplex nickel-base alloy containing about 30 mass% iron, 10 mass% aluminium and 8 mass% chromium was determined in both air and hot process gases containing methanekydrogen, sulphur dioxide and hydrogen sulphide, respectively. It was found that the corrosion resistance against carburisation, sulphidation and oxidation was excellent due to the formation of a dense, protective alumina scale. The adherence of the alumina scale was increased by an addition of 0.1 mass% hafnium. The concentration of chromium was found to have a remarkable impact on the oxidation and high temperature corrosion resistance. Alloys without chromium showed increased corrosion rates in both air and sulphur-containing gas atmospheres due to the initial formation of nickel oxides. In sulphidising SO,-and H,S-containing gases at least 4 mass% chromium are required to stabilise the formation of alumina and to prevent the formation of nickel/sulphur compounds.Das Hochtemperaturkorrosionsverhalten einer neuen Duplex-Nickelbasislegierung mit etwa 30 Masse% Eisen, 10 Masse% Aluminium und 8 Masse% Chrom wurde an Luft und in heiSen Prod g a s e n mit Methan, Schwefeldioxid oder Schwefelwasserstoff untersucht. Es zeigte sich, daB die Legierung wegen der Bildung dichter, schutzender Aluminiumoxidschichten eine ausgezeichnete Korrosionsbestandigkeit aufweist. Durch einen Zusatz von 0,l Masse% Hafnium kann die Haftung der Oxidschicht verbessert werden. Der Gehalt an Chrom hat einen erheblichen EinfluS auf die Oxidations-und Hochtemperaturkorrosionsbestandigkeit der Legierung. Legierungen ohne Chrom wiesen hohe Korrosionsraten sowohl an Luft als auch in schwefelhaltigen Atmospharen auf, dieser Effekt kann auf die anfangliche Bildung von Nickeloxiden zuruckgefiihrt werden. In sulphidierenden SO,-und H,S-haltigen Gasen sind mindestens 4 Masse% Chrom erforderlich, um die Bildung von Aluminiumoxid zu begiinstigen und die Bildung von Nickel-Schwefel-Verbindungen zu verhindern.sures of some industrial processes are listed, clearly shows, that in several coal conversion and petrochemical processes chromia becomes unstable whereas alumina A1,0, is even formed under conditions with very low oxygen partial pressures due to its high thermodynamical stability. Materials forming alumina scales have other advantages, too. The rate constant of alumina formation is lower than that of chromia formation and unlike chromia, alumina does not evaporate at temperatures above 950 "C. Consequently there are 0 VCH Verlagsgesellschaft mbH, D-69451 Weinheim, 1997

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

High temperature corrosion behaviour of a new Ni‐30Fe‐10Al‐Cr‐Alloy

Klöwer¹,

Sauthoff

1997

Materials & Corrosion

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“…if once formed, alumina scales should be protective in oxygen deficient sulphidising H2S-environments at intermediate temperatures, too [27]. 10 wt% aluminium in and prevent sulphidation in oxygen deficient H2S-gases at 550°C.…”

Section: Corrosion In Hot Process Gasesmentioning

confidence: 99%

High temperature Corrosion behaviour of iron aluminides and iron‐aluminium‐chromium alloys

Klöwer¹

1996

Materials & Corrosion

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The high temperature corrosion of different iron aluminides and iron‐aluminium‐chromium alloys containing between 6 and 17 wt% aluminium, 2 and 10 wt% chromium and additions of mischmetal has been investigated in air as well as in carburising, chlorinating and sulphidising environments. It was found that all alloys showed excellent corrosion resistance to both oxidation in air and carburisation in CH4/H2 up to at least 1100°C and to sulphidation in SO2/air up to at least 850°C. In these environments the corrosion behaviour is not influenced by the concentrations of aluminium and chromium. In oxygen deficient H2S‐atmospheres, however, the corrosion behaviour depends sensitively on the aluminium and chromium concentration. At least 12 wt% aluminium in chromium‐free alloys or 10 wt% aluminium in alloys containing 10 wt% chromium are required to provide sulphidation resistance at 550°C. The chlorination resistance of iron‐aluminium‐chromium alloys is low due to their formation of volatile aluminium chlorides.

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“…This is consistent with the variable corrosion observed for this alloy on exposure to the non-equilibrium gas of the Petten tests at 600°C. 48 Here, a few specimens of the alloy were able to establish rapidly a thin, complete Al 2 0rrich layer, giving good protection, while most specimens produced thicker, sulphide-rich scales, as described in the next paragraph. However, protective Al 2 0 3 -scales were established on a Fecralloy (Fe-15%Cr-4%Al-0.3%Y) in an HCl-free gasifier environment at 450°C.…”

Section: Silicajorming and Alumina-forming Alloysmentioning

confidence: 91%

Laboratory studies involving corrosion in complex, multi-component gaseous environments at elevated temperatures

Stott

Norton

1997

Materials at High Temperatures

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The basis for the development of laboratory test programmes to provide data relevant to the selection and design of alloys for use in complex, multi-component gases, such as those produced during coal gasification, is discussed and some of the advantages and disadvantages are considered. The results from recent laboratory studies involving exposures of alloys in environments of low oxygen and high sulphur partial pressures at 300-700°C are reviewed and compared, with emphasis on non-equilibrium gases that approximate to those of gasifier systems. Conventional Cr 2 0 3 -forming alloys develop sulphide scales in this temperature range, but these do not necessarily lead to unacceptable rates of metal loss. The corrosion rate is usually determined by the composition and integrity of the inner scale layer, and can be very low if the layer consists of an oxide or a mixture of oxides and acceptably low if it consists of a refractory metal sulphide or a chromium-rich sulphide, such as FeCr 2 S 4 • However, mixed oxides plus sulphides are much less protective, often giving unacceptably high corrosion rates. The additions of oxide-forming elements, particularly silicon or aluminium, to iron (nickel)-chromium-base alloys can facilitate the formation of the oxide layer, thereby giving improved corrosion resistance.

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A laboratory study of the corrosion behaviour of Alloys exposed in a non‐equilibrated coal gasification atmosphere at 600°C

Cited by 6 publications

References 3 publications

High temperature corrosion behaviour of a new Ni‐30Fe‐10Al‐Cr‐Alloy

High temperature corrosion behaviour of a new Ni‐30Fe‐10Al‐Cr‐Alloy

High temperature Corrosion behaviour of iron aluminides and iron‐aluminium‐chromium alloys

Laboratory studies involving corrosion in complex, multi-component gaseous environments at elevated temperatures

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