Behaviour of NiAl APS‐coatings in chlorine‐containing atmospheres

Latreche, Hadj; Doublet, Sébastien; Tegeder, G.; Wolf, Gerhard; Masset, Patrick J.; Weber, Till; Schütze, M.

doi:10.1002/maco.200804140

Cited by 8 publications

(15 citation statements)

References 22 publications

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“…It has already been highlighted in [21] that Mo-W alloys offer better corrosion resistance than pure molybdenum. Furthermore in [22], it has also been observed that a very small amount of aluminium in the a-Mo phase (high molybdenum content phase) is sufficient to significantly increase the corrosion resistance.…”

Section: Molybdenummentioning

confidence: 95%

Development of Corrosion Assessment Diagrams for High Temperature Chlorine Corrosion Part II: Development of “Dynamic” Quasi-stability Diagrams

Latreche

Doublet²,

Schütze

2009

Oxid Met

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The corrosion of metals at high temperatures in halogen containing environments differs from most other types of high temperature corrosion in that in addition to solid and liquid corrosion products volatile phases are also formed. The latter are not covered by the usual thermodynamic stability diagrams, which are often used for prediction of the corrosion products formed, and indirectly on whether corrosion has to be regarded as critical or not. The present paper aims at including the situation where gas phase corrosion products determine the extent of corrosion and a new type of diagram is developed and discussed for the example of chlorine containing environments. Part I of this paper (Latreche et al. Oxid Met 2009) was dedicated to the establishment of the basis for a new extended approach to a corrosion risk assessment diagram called the ''dynamic'' quasi-stability diagram. The present part deals with the principles of the new type of diagram and the establishment of specific diagrams for the most common alloying elements, i.e. Fe, Ni, Mo, Cr, Si, Al. For the development of the specific diagrams, the calculation of gas viscosities and gas diffusion coefficients of all relevant volatile potential corrosion products was conducted, with methods specified in the paper. The new ''dynamic'' quasi-stability diagrams were then compared to experimental results from kinetics investigations of pure metals, which showed quite good agreement with the experimental observations. Furthermore, the diagrams were used to assess H. Latreche the behaviour of the metallic elements in alloys. Again, in this case good agreement between prediction and experimental results was observed if the specific role of the different elements in the corrosion behaviour of the alloys was taken into account.

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Section: Molybdenummentioning

confidence: 95%

Development of Corrosion Assessment Diagrams for High Temperature Chlorine Corrosion Part II: Development of “Dynamic” Quasi-stability Diagrams

Latreche

Doublet²,

Schütze

2009

Oxid Met

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“…They reported an excellent performance for Ni 3 Al up to 1000 °C for pure NaCl salt. Apart from this, also the performance of nickel and iron aluminides in oxygen and chlorine gas mixtures has been investigated in several studies . In general, it has been observed in these investigations that the performance of aluminide coatings is superior to that of the corresponding chromia‐forming substrate alloy.…”

Section: Introductionmentioning

confidence: 99%

Application of aluminum diffusion coatings to mitigate the KCl‐induced high‐temperature corrosion

Kiamehr

Lomholt²,

Dahl

et al. 2016

Materials & Corrosion

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Pack cementation was used to produce Fe1−xAl and Fe2Al5 diffusion coatings on ferritic‐martensitic steel P91 and a Ni2Al3 diffusion coating on pure nickel. The performance of diffusion coatings against high‐temperature corrosion induced by potassium chloride (KCl) was evaluated by exposing the samples at 600 °C for 168 h in static lab air under KCl deposit. In addition, a salt‐free experiment was performed for comparison. Microstructure, chemical and phase composition of the samples were analyzed with scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDS) and X‐ray diffractometry (XRD) before and after the exposures. It was found that all the diffusion coatings formed protective oxides under salt‐free exposure in air. Under the salt deposit, Fe1−xAl showed local failure while on large parts of the sample a protective layer had formed. Fe2Al5 was attacked over the entire surface and the dominant mode of attack was selective aluminum removal. Ni2Al3 showed excellent performance and no sign of attack was observed anywhere on the sample.

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“…In this part of the curve the thin oxide formed during the "incubation" period is completely consumed and the mass loss corresponds to the formation and the volatilization of metal chlorides arising from the "fresh" alloy surface. In the linear part of the curve mass variation versus time the kinetic constants of vaporization k v varied between 3 and 10.10 -6 g.cm -2 .s -1 for NiAl (1-x) Hf x (x=0…0.2) alloys and are in the same order of magnitude as those previously obtained for NiAl alloys [7]. At this temperature the k v values obtained for the NiAl (1-x) Hf x (x=0…0.2) are at least three times lower than those obtained for example for the alloy B2 under the same conditions.…”

Section: Cte Measurementsmentioning

confidence: 92%

“…Experimentally, NiAl has been previously investigated and exhibits a good corrosion resistance in chlorine based environment [7]. However due to its high CTE it does not fit the whole range of those steels to be protected.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behavior of NiAl_(1-x)Hf_x (x=0...0.2) Alloys in Chlorine Based High Temperature Environments

2009

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Five compositions of (Ni0.5Al0.5)(1-x)Hfx (x=0...0.2) alloys were prepared by centrifugal casting in an inductive furnace. The cast alloys exhibits 3 phases: β-NiAl, NiAlHf (Laves) and Ni2AlHf (Heussler). Their CTEs were found to vary linearly with the hafnium content. Hafnium can be used to adjust the CTE to the substrate CTE. At the same time the prepared alloys are corrosion resistant in chlorine based high temperature environments. For hafnium contents higher than 10 at.%t, it was shown that hafnium addition improves the Cl2 corrosion resistance compared to binary NiAl alloys.

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Behaviour of NiAl APS‐coatings in chlorine‐containing atmospheres

Cited by 8 publications

References 22 publications

Development of Corrosion Assessment Diagrams for High Temperature Chlorine Corrosion Part II: Development of “Dynamic” Quasi-stability Diagrams

Development of Corrosion Assessment Diagrams for High Temperature Chlorine Corrosion Part II: Development of “Dynamic” Quasi-stability Diagrams

Application of aluminum diffusion coatings to mitigate the KCl‐induced high‐temperature corrosion

Corrosion Behavior of NiAl_(1-x)Hf_x (x=0...0.2) Alloys in Chlorine Based High Temperature Environments

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Behaviour of NiAl APS‐coatings in chlorine‐containing atmospheres

Cited by 8 publications

References 22 publications

Development of Corrosion Assessment Diagrams for High Temperature Chlorine Corrosion Part II: Development of “Dynamic” Quasi-stability Diagrams

Development of Corrosion Assessment Diagrams for High Temperature Chlorine Corrosion Part II: Development of “Dynamic” Quasi-stability Diagrams

Application of aluminum diffusion coatings to mitigate the KCl‐induced high‐temperature corrosion

Corrosion Behavior of NiAl(1-x)Hfx (x=0...0.2) Alloys in Chlorine Based High Temperature Environments

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Corrosion Behavior of NiAl_(1-x)Hf_x (x=0...0.2) Alloys in Chlorine Based High Temperature Environments