Microprocesses of metal dusting on nickel and Ni-base alloys

Schneider, Reinhard; Pippel, Eckhard; Woltersdorf, J.; Strauß, Silke; Grabke, H. J.

doi:10.1002/srin.199701796

Cited by 69 publications

(45 citation statements)

References 10 publications

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“…From the point of stability for carbides, high nickel alloys do not have any metastable carbide as an intermediate. Another mechanism 18,19) has been proposed as described below: (e) continuous carbon charging into the metal matrix comes to the supersaturation at the metal surface, resulting in the precipitation of graphite. (f) inward growth of graphite destructs the metal under transfer of metal particles into the catalyzed coke.…”

Section: Introductionmentioning

confidence: 99%

A Metallurgical Approach to Metal Dusting of Nickel-Base Alloys

Nishiyama¹,

Kudo²,

Ōtsuka³

2005

Mater. Trans.

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Preliminary laboratory corrosion tests of two conventional Ni-base alloys were conducted at 650 C for 200 h in various CO-H 2 -CO 2 -H 2 O gas mixtures. For gas mixtures of high a c and CO content, alloy 600 (75 mass %Ni-15%Cr) specimens lost its mass due to metal dusting and deposition of coke was heavy on the surface of the specimen. Meanwhile, any pit formation was not occurred on the alloy 690 (60%Ni-30%Cr) specimens. Microscopic observation indicated that for the corroded Ni-base alloy specimens, inward diffusion of carbon presumably at cracks and flaws in the oxide scale was prominent. Carbon in the diffusion zone reacted with chromium to precipitate carbides in the matrix, followed by the ''direct'' formation of graphite platelets with a lamellar structure at the revealed metal surface. This direct precipitation of graphite platelets can be considered by a eutectoid reaction, which is similar to the pearlite transformation observed in Fe-C system. In the lamellar structure, the matrix thinned with the growth of graphite plates, and small metal particles of Ni and Fe which may catalyze the coke deposition reaction were crumbled and detached from the lamella.

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Section: Introductionmentioning

confidence: 99%

A Metallurgical Approach to Metal Dusting of Nickel-Base Alloys

Nishiyama¹,

Kudo²,

Ōtsuka³

2005

Mater. Trans.

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“…For nickel, Ni-base materials and steels with NiaFe b 2a3 another simpler reaction sequence applies, not involving the instable intermediate M 3 C [6,15,16]. After oversaturation of the metal phase, direct graphite growth into the metal phase follows, C-atoms from the supersaturated solid solution attaching to graphite basal planes [16].…”

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confidence: 98%

Thermodynamics, mechanisms and kinetics of metal dusting

Grabke

1998

Materials and Corrosion

208

127

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A survey is given on recent research on “metal dusting” i.e. a catastrophic carburization or rather graphitization of metals and alloys occuring in carbonaceous atmospheres at carbon activities aC>1. The thermodynamics are explained, the mechanisms for iron, low and high alloy steels, nickel and Ni‐base alloys are described and the kinetics derived for iron and low alloy steels. Protection against metal dusting is possible by the presence of sulfur in the atmosphere, since adsorbed sulfur retards carbon transfer and hems graphite nucleation. Also dense oxide layers are protective, the preconditions for the formation of Cr‐rich protectivee layers on steels and Ni‐base alloys are shortly presenteed.

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“…The mechanisms of metal dusting, as generally reported [4,8,11,15,16], are summarised briefly as follows. In iron-base alloys, adsorbed carbon saturates the metal surface and forms cementite.…”

Section: Introductionmentioning

confidence: 99%

“…Extensive work in this area was later carried out by Grabke et al [5][6][7][8] .Recently, Szakalos has presented refinements to the mechanisms of metal dusting which include the role of oxidation [9][10][11]. Review papers by Grabke [12] and Jones and Baumert [13] provide thorough summaries of the subject of metal dusting.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of metal dusting using thermal spray coatings and laser treatment

Voisey

Liu

Stott

2006

Surface and Coatings Technology

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Alloy 600 and Alloy 800H are susceptible to metal dusting. Both alloys were thermally sprayed with two different corrosion resistant coatings: Ni50Cr and Ni31Cr11Al0.6Y. Laser remelting was used to enhance further the effectiveness of these coatings to resist metal dusting by eliminating interconnected porosity and improving coating adhesion.Uncoated, coated and laser-treated coated samples of Alloy 600 and Alloy 800H were exposed to a mixed gas atmosphere (20% H 2, 80% CO at 650°C). Samples were examined in plan and cross-section using optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The extent of carbon deposition was tracked by mass difference measurements at intervals during exposure.The thermally sprayed coatings enhanced metal dusting resistance by acting as physical barriers to carbon ingress. The NiCrAlY coating performed well on both substrates. The NiCr coating itself underwent metal dusting and spalled from Alloy 800H due partly to CTE mis-match stresses. Laser treatment of both coatings successfully eliminated interconnected porosity and hence enhanced metal dusting resistance.

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Microprocesses of metal dusting on nickel and Ni-base alloys

Cited by 69 publications

References 10 publications

A Metallurgical Approach to Metal Dusting of Nickel-Base Alloys

A Metallurgical Approach to Metal Dusting of Nickel-Base Alloys

Thermodynamics, mechanisms and kinetics of metal dusting

Inhibition of metal dusting using thermal spray coatings and laser treatment

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