Oxide-Layer Formation and Stability on a Nickel-Base Alloy in Impure Helium at High Temperature

Rouillard, Fabien; Cabet, C.; Wolski, Krzysztof; Pijolat, Michèle

doi:10.1007/s11085-007-9065-y

Cited by 47 publications

(40 citation statements)

References 13 publications

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“…On the other hand, Mn was only concentrated on the outer layer and not on the inner Cr 2 O 3 layer, suggesting that the Cr 2 O 3 layer was covered with a thin outer MnCr 2 O 4 oxide layer, as reported in previous studies [48,49]. The spinel oxide layer MnCr 2 O 4 was formed at the early stage of oxidation and became thicker and continuous as the oxidation progressed.…”

Section: Discussionsupporting

confidence: 74%

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

et al. 2010

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Ni-base superalloy IN 718 was cyclically oxidized in laboratory air at temperatures ranging from 750 to 950°C for up to 12 cycles (14 h/cycle). The kinetic behaviour as well as the surface morphology, and the oxide phases of the scales were characterized by means of weight gain measurements, cyclic oxidation kinetics, scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) analysis techniques. The results showed that as the oxidation temperature increased, the oxidation rate, the external scale thickness, and internal oxidation zone increased. It was suggested that the oxidation rate was controlled by the diffusion of substrate elements in the alloy and the inward diffusion of oxygen through the oxide scale. The oxidation kinetics followed a sub-parabolic rate law and, the activation energy of oxidation was 249 ± 20 kJ mol -1 . The scaling process was controlled mainly by the diffusion of chromium, titanium, manganese, and oxygen ions through the chromia scale. IN 718 showed low weight gain and very slow reaction rates of substrate elements at 750°C. At 850°C, a continuous and very thin oxide scale was formed. At 950°C, XRD and EDS-elemental mapping analysis revealed that a complex oxide scale had formed. It consisted of an outermost layer of TiO 2 -MnCr 2 O 4 spinels, inner layer of Cr 2 O 3 , and the inner most layer composed of Ni 3 Nb enriched with Nb, Ti and Al oxides underneath the chromia layer. The oxide scale at this temperature seemed to be thicker layer, significant spallation and volatilization had apparently occurred, and greater internal corrosion was identified. The doping effect of titanium was observed, where it was found to be diffused through the chromia scale to form TiO 2 at the oxide-gas interface as well as internally and at the oxide alloy interface.

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Section: Discussionsupporting

confidence: 74%

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

et al. 2010

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“…Even if these impurities are highly diluted in helium -only between a few tens to hundreds of µbar -they can react at high temperature, typically between 850°C and 1000°C, with structural metallic materials. Gas-metal interactions involved in HTR heat exchangers have been discussed in numerous papers published in the past three decades [1][2][3][4][5][6] and more recently in France [7][8][9][10][11][12][13][14] and in the USA [15][16][17]. These works have demonstrated that depending on the composition of the chromia-former alloy, on the working temperature (850-1000°C) and on the partial pressures of the various gas species in helium, two main behaviours could be distinguished: either a passive corrosion behaviour based on the formation of a stable, slow-growing, Cr-rich oxide layer on the surface or an active corrosion with the destruction of the surface oxide layer and the subsequent decarburization or carburization of the alloy [9].…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of reaction between water vapor, carbon monoxide and a chromia-forming nickel base alloy

et al. 2013

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The kinetic aspects of the competitive reaction of CO and H 2 O in the formation of chromia layer on a nickel base alloy at high temperature were studied by thermogravimetry combined to gas phase chromatography. It was shown that competitive adsorption occurred between both molecules and that whatever P CO /P H2O ratio, CO mainly reacted in the first instants of oxidation and H 2 O became the main long-term oxidant species. After an interfacial and diffusion mixed kinetic regime, the long-term oxidation rate was parabolic and did not depend on the water vapour content in the gas phase. The oxidation kinetics was well described by considering that the rate limiting step was the outwards diffusion of interstitial chromium cations in the oxide layer.

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“…Changes in the surface oxide (primarily Cr 2 O 3 ) and the composition of the metal may compromise the effectiveness of the barrier. Reaction of the chromia with the carbide in the steel to form carbon dioxide has been observed in long term elevated temperature tests at INL [26]. Mass 44 (CO 2 ) was detected in the primary gas stream in the permeation tests discussed here.…”

Section: Discussionmentioning

confidence: 68%

Tritium Permeability of Incoloy 800H and Inconel 617

Winston¹,

Calderoni²,

Humrickhouse³

2012

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Design of the Next Generation Nuclear Plant (NGNP) reactor and its hightemperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented.To support engineering design of the NGNP reactor components, tritium permeability values for Inconel 617 and Incoloy 800H were determined in Fiscal Year 2011 using a measurement system designed and fabricated at Idaho National Laboratory. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. The experiments were repeated in FY-12 with Incoloy 800H using reconfigured tritium detection and in-process hydrogen measurement to reduce uncertainties from the first series of tests. The tritium permeability of Incoloy 800H was measured in the temperature range 700 to 950°C and at primary concentrations of 0.5 to 125 (atom) parts per million tritium in helium (partial pressures of 10 -7 atm) -four orders of magnitude lower partial pressure than used in the hydrogen permeation testing. The new data provide some evidence that permeation has become surface-limited, as expected for sufficiently low pressures. In this case, the resultant tritium flux is linearly related to the pressure, unlike the diffusionlimited (high pressure) regime, in which it is proportional to the square root of pressure. In the surface-limited regime, the proportionality constant is not the permeability K, but the dissociation rate constant K d . Since the present measurements appear to span at least a part of the transition region between these two extremes, a quantitative estimate of K d could not be obtained, but the theory and experimental requirements for doing so are outlined. vi vii

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Oxide-Layer Formation and Stability on a Nickel-Base Alloy in Impure Helium at High Temperature

Cited by 47 publications

References 13 publications

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

Kinetics and mechanism of reaction between water vapor, carbon monoxide and a chromia-forming nickel base alloy

Tritium Permeability of Incoloy 800H and Inconel 617

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