The Reaction between Oxygen and Thorium

Levesque, Pascal; Cubicciotti, Daniel

doi:10.1021/ja01149a037

Cited by 26 publications

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“…Examination of a separate sample which had been oxidized for a shorter period indicated that, as with magnesium, the oxide scale gradually extended laterally over the sample surface. Levesque and Cubicciotti (14), in an experiment covering a much shorter period, found an increase in rate corresponding to branch AB, but the actual weight gains and times were different from those in the present work. The sharp rise in oxidation rate at A probably corresponds to a breakdown of the continuous oxide layer in local regions thus marking the beginning of lateral growth.…”

Section: Resultscontrasting

confidence: 84%

The Formation of Porous Oxides on Metals

Aylmore

Gregg

Jepson

1959

J. Electrochem. Soc.

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The porosity of the oxide scales formed on a number of metals during oxidation in dry oxygen has been investigated by measurements of specific surface and of density. The oxides formed during the linear oxidation of the eight metals: calcium, cerium, lead, magnesium, niobium, thorium, tungsten, and uranium are porous whereas those formed during the parabolic oxidation of copper and cobalt are impervious to oxygen gas.The oxidative behavior of a metal in oxygen depends to a marked extent on the physicochemical properties of the oxide layer formed on its surface. If the layer of reaction product remains continuous during oxidation, reaction can proceed only by the diffusion of either one or both of the reactants in the ionized form through the oxide lattice. In some cases, as with aluminum (1, 2) at 600~ the rate of oxidation falls off to a negligibly small value as time proceeds, while in others, as for example copper (3) at 1000~ the oxidation follows a parabolic rate law and the rate of attack is such that a sheet of material is oxidized completely in a few hours.On the other hand, some metals, usually above a certain characteristic temperature, oxidize at a constant rate which is maintained until the whole of the metal is consumed, a behavior exemplified by magnesium (4) at 500~This "linear oxidation" usually is interpreted in terms of the formation of an oxide scale which is porous in the sense that oxygen gas is able to pass freely through its thickness; the rate of oxidation is believed to be controlled by the rate of diffusion either of metal ions or oxygen anions through a thin barrier film of oxide adhering to the metal.The present study was undertaken in order to provide experimental evidence for the postulated porosity of the oxide layer formed during linear, or almost linear, oxidation and to show that the oxide layer formed during parabolic oxidation is, in fact, impervious to oxygen gas. The metals whose oxides were investigated were calcium, cerium, lead, magnesium, niobium, thorium, tungsten, and uranium, which oxidize at a linear rate, and cobalt and copper which oxidize at a parabolic rate. Two distinct experimental techniques were used to investigate each of the oxide products: the specific surface was measured by the method of krypton sorption (5) at --195~ and the density (6) by immersion in mercury and in carbon tetrachloride, respectively. ExperimentalEach oxide was prepared by oxidizing the metal in dry oxygen at atmospheric pressure in a glass or silica reaction chamber on a thermal balance. The experimental arrangement was the same as that previously described (4) except that the oxygen was further dried by passing it through a column packed with Linde molecular sieves (7).The percentage purity of the metals was: Ca, ~99.4; Ce, ~99.99; Co, 99.999; Cu, 99.999; Pb, 99.998; Mg, 99.95; Nb, ~99.8; Th, ~99.6; W, >99.95; and U, ~99.9. Except for calcium, cerium, and lead, the metals were in the form of sheet, 1/32 in. thick for niobium and tungsten and 1/16 in. thick for the others; a sample in ...

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Section: Resultscontrasting

confidence: 84%

The Formation of Porous Oxides on Metals

Aylmore

Gregg

Jepson

1959

J. Electrochem. Soc.

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“…As shown in Figure 13, the scaling rate measurements made in this study fall intermediate between the two previously reported studies (71,72) with the slope in the 800° to 1000°C range matching quite closely to the slope observed by Levesque and Cubicciotti (72) at low temperatures.…”

Section: Oxygen Permeability Of Thoriasupporting

confidence: 89%

Study of the mass and charge transport in thoria

Choudhury

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“…The primary thorium metal corrosion reaction proceeds by Th + 2H 2 O fi ThO 2 + 2H 2 . Thorium hydride may be formed as a consequence of a side reaction, but it has not been detected in quantity [44][45][46][47][48].…”

Section: Thorium Corrosion Productsmentioning

confidence: 99%

Drying characteristics of thorium fuel corrosion products

Smith

2004

Journal of Nuclear Materials

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The Reaction between Oxygen and Thorium

Cited by 26 publications

References 0 publications

The Formation of Porous Oxides on Metals

The Formation of Porous Oxides on Metals

Study of the mass and charge transport in thoria

Drying characteristics of thorium fuel corrosion products

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