Void Formation in Growing Oxide Scales with Schottky Defects and P-Type Conduction

Maruyama, Toru; Akiba, Kojiro; Ueda, Mitsutoshi; Kawamura, Kazutaka

doi:10.4028/www.scientific.net/msf.595-598.1039

Cited by 5 publications

(3 citation statements)

References 5 publications

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“…6a and b). Pores are generally supposed to arise from the accumulation of vacancies [48,49]. Therefore it is not surprising to obtain more porosities in the high P(O2) atmosphere since the presence of chromium vacancies is more significant in this case.…”

Section: Oxide Scale Characteristicsmentioning

confidence: 99%

Oxidation of Ni-Cr alloy at intermediate oxygen pressures. I. Diffusion mechanisms through the oxide layer

Schmucker

Petitjean²,

Martinelli

et al. 2016

Corrosion Science

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Section: Oxide Scale Characteristicsmentioning

confidence: 99%

Oxidation of Ni-Cr alloy at intermediate oxygen pressures. I. Diffusion mechanisms through the oxide layer

Schmucker

Petitjean²,

Martinelli

et al. 2016

Corrosion Science

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“…  and the defect structure in metal oxides. [9] The sign of MO n t   is identical to that of the last term in Eq. (31).…”

Section: Relation Between N Tmentioning

confidence: 87%

Void Formation in the Growing Scale Induced by the Divergence of the Diffusive Ionic Flux in High Temperature Oxidation of Metals

Maruyama

Ueda

Kawamura

2009

DDF

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Voids are frequently generated and dispersed in oxide scales formed in high temperature oxidation of metals. The divergence of ionic flux may play an important role in the void formation in a growing scale. Kinetic equations were derived for describing chemical potential distribution, ionic fluxes and their divergence in the scale. The divergence was found to be the measure of void formation. Defect chemistry in scales is directly related to the sign of divergence and gives an indication of the void formation behavior. The quantitative estimation on the void formation was successfully applied to a growing magnetite scale in high temperature oxidation of iron at 823 K.

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“…Such void formation should be caused by a counter diffusion of vacancies due to the outward diffusion of Fe ions across the whole oxide scale and the nucleation of voids in the oxide scale. Ueda et al [23][24][25][26][27] quantitatively estimated the rate of void formation by divergence of ionic flux under an oxygen potential gradient, and could evaluate the void formation behavior in growing oxide scale well. It is reasonable to consider that void nucleation initially occurs heterogeneously at the outer/inner scale interface, and grows laterally to form a gap at the interface based on the cross-sectional observation in Fig.…”

Section: Voids In the Oxide Scalementioning

confidence: 99%

Time Change in Scale Microstructure of Fe-5 mass%Ni Alloy at 1200°C

2020

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Ni containing steel is known to form a complex oxide scale, which consists of an outer layer of Feoxides and an inner layer of FeO with complicated distribution of Ni(Fe) metal particles. Due to the complex microstructure, descaling of the oxide scale formed on Ni containing steel during a hot-rolling process is very difficult. In order to improve the descaling process, microstructural control of the inner oxide layer to eliminate its detrimental effect is necessary. In this study, the change in microstructure of the outer and inner layers formed on Fe-5 mass%Ni alloy during oxidation is investigated. In particular, the change in the microstructure of the metal particles in the inner layer with oxidation time is considered. The inner layer consisted of FeO, Ni(Fe), and voids. The concentration of Ni in the Ni(Fe) was found to increase across the inner layer from the scale/steel interface toward the outer/inner scale interface due to the equilibrium Ni concentration in the Ni(Fe) particles with FeO, which corresponded to the oxygen potential gradient in the inner layers. The number and area fraction of the Ni(Fe) metal particles decreased, whereas the size of the particles increased with oxidation time. This coarsening of the metal particles was proposed to be due to Ostwald ripening.

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Void Formation in Growing Oxide Scales with Schottky Defects and P-Type Conduction

Cited by 5 publications

References 5 publications

Oxidation of Ni-Cr alloy at intermediate oxygen pressures. I. Diffusion mechanisms through the oxide layer

Oxidation of Ni-Cr alloy at intermediate oxygen pressures. I. Diffusion mechanisms through the oxide layer

Void Formation in the Growing Scale Induced by the Divergence of the Diffusive Ionic Flux in High Temperature Oxidation of Metals

Time Change in Scale Microstructure of Fe-5 mass%Ni Alloy at 1200°C

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