Void Formation in Magnetite Scale Formed on Iron at 823 K -Elucidation by Chemical Potential Distribution-

2006 ◽  
pp. 37-44 ◽  
Author(s):  
Mitsutoshi Ueda ◽  
Kenichi Kawamura ◽  
Toshio Maruyama
Keyword(s):  
Potential Distribution ◽  
Chemical Potential ◽  
Void Formation

Void Formation at the Interface of the Duplex Scale Formed on Fe-5Cr Alloy at 773 K

2011 ◽  
Vol 696 ◽  
pp. 34-38 ◽  
Author(s):  
Mitsutoshi Ueda ◽  
Kenichi Kawamura ◽  
Toshio Maruyama
Keyword(s):  
Potential Distribution ◽  
Chemical Potential ◽  
Volume Fraction ◽  
Void Formation ◽  
Low Oxygen ◽  
Duplex Scale ◽  
Calculated Volume ◽  
Oxide Ion ◽  
Oxygen Chemical Potential ◽  
Good Agreement

Void formation in a duplex scale formed on Fe-5Cr alloy at 773 K has been elucidated by oxygen chemical potential distribution, the flux of oxide ion and its divergence. The calculation predicts that voids preferentially form at the interface between inner and outer scales in the low oxygen partial pressure in which the predominant defect of iron is interstitial ion. The flux of oxide ion changes discontinuously at this interface and the divergence of the flux gives voids. Calculated volume fraction of voids at this interface is in good agreement with that has been measured.

Chemical Potential Distribution and Void Formation in Magnetite Scale Formed in Oxidation of Iron at 823K

2004 ◽  
Vol 461-464 ◽  
pp. 807-814 ◽  
Author(s):  
Toshio Maruyama ◽  
Naoya Fukagai ◽  
Mitsutoshi Ueda ◽  
Kenichi Kawamura
Keyword(s):  
Potential Distribution ◽  
Chemical Potential ◽  
Void Formation

Void Formation in Magnetite Scale Formed on Iron at 823 K -Elucidation by Chemical Potential Distribution-

2006 ◽  
Vol 522-523 ◽  
pp. 37-44 ◽  
Author(s):  
Mitsutoshi Ueda ◽  
Kenichi Kawamura ◽  
Toshio Maruyama
Keyword(s):  
Oxide Scale ◽  
Diffusion Coefficients ◽  
Potential Distribution ◽  
Boundary Diffusion ◽  
Chemical Potential ◽  
Effective Diffusion ◽  
Void Formation ◽  
Lattice Diffusion ◽  
Effective Diffusion Coefficients ◽  
Oxide Ion

Estimation of void formation in oxide scale is important for predicting exfoliation of the oxide scale. Void formation in magnetite scale formed on iron at 823 K has been elucidated by chemical potential distribution, flux of oxide ion and its divergence. This calculation also estimates a effective diffusion coefficient, which includes both lattice diffusion and grain boundary diffusion in magnetite scale. The resulting effective diffusion coefficients give the quantitative elucidation of the morphology of the magnetite scale. The divergence of oxide ion explains well a position and an amount of void in magnetite scale.

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

2009 ◽  
Vol 289-292 ◽  
pp. 1-13 ◽  
Author(s):  
Toshio Maruyama ◽  
Mitsutoshi Ueda ◽  
Kenichi Kawamura
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Chemical Potential ◽  
Quantitative Estimation ◽  
Kinetic Equations ◽  
Void Formation ◽  
Ionic Flux ◽  
Temperature Oxidation ◽  
Ionic Fluxes ◽  
Formation Behavior

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.

Capacitance dependence of chemical potential distribution in supported nanoclusters

2004 ◽  
Vol 566-568 ◽  
pp. 402-405 ◽  
Author(s):  
Taizo Ohgi ◽  
Yukihiro Sakotsubo ◽  
Daisuke Fujita ◽  
Youiti Ootuka
Keyword(s):  
Potential Distribution ◽  
Chemical Potential

Direct Evaluation of Oxygen Chemical Potential Distribution in an SOFC Cathode by In Situ X-Ray Absorption Spectroscopy

2013 ◽  
Vol 57 (1) ◽  
pp. 1925-1932 ◽  
Author(s):  
Y. Fujimaki ◽  
H. Watanabe ◽  
Y. Terada ◽  
T. Nakamura ◽  
K. Yashiro ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Potential Distribution ◽  
Chemical Potential ◽  
Sofc Cathode ◽  
Direct Evaluation ◽  
X Ray ◽  
X Ray Absorption ◽  
Oxygen Chemical Potential

The effects of surface absorbed monolayer microdiffraction patterns

1988 ◽  
Vol 46 ◽  
pp. 680-681
Author(s):  
M. Pan ◽  
J.M. Cowley
Keyword(s):  
Surface Potential ◽  
Electron Probe ◽  
Potential Distribution ◽  
Crystal Surface ◽  
Normal Direction ◽  
Surface Image ◽  
Extended Surface ◽  
Gas Molecules ◽  
Surface Nature ◽  
Electron Microdiffraction

Electron microdiffraction patterns, obtained when a small electron probe with diameter of 10-15 Å is directed to run parallel to and outside a flat crystal surface, are sensitive to the surface nature of the crystals. Dynamical diffraction calculations have shown that most of the experimental observations for a flat (100) face of a MgO crystal, such as the streaking of the central spot in the surface normal direction and (100)-type forbidden reflections etc., could be explained satisfactorily by assuming a modified image potential field outside the crystal surface. However the origin of this extended surface potential remains uncertain. A theoretical analysis by Howie et al suggests that the surface image potential should have a form different from above-mentioned image potential and also be smaller by several orders of magnitude. Nevertheless the surface potential distribution may in practice be modified in various ways, such as by the adsorption of a monolayer of gas molecules.

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