High Pressure Oxidation of Niobium

Bridges, D.W.; Fassell, W.M.

doi:10.1149/1.2430322

Cited by 34 publications

(7 citation statements)

References 4 publications

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“…According to the results of [232] the activation energy of niobium oxides in pure oxygen is aboutl 0 kcal/mole at 500-600°C.…”

Section: Interaction With Oxygenmentioning

confidence: 98%

Physical Metallurgy of Refractory Metals and Alloys

Savitskii¹,

Burkhanov²

1995

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All rights reservedNo part of this publication may be reproduced in any form without written permission from the publisher PREFACE TO THE AMERICAN EDITIONThe principal reasons which induced the authors to write this book and the features of the book are set forth in the preface to the Russian edition.That section of the science of metals which in Russian is called "metallovedenie" or the "physical chemistry of metals" is generally referred to in scientific and technical literature published in the English language by the term "physical metallurgy." These concepts are much broader than the term" metallography," used in the scientific and technical literature of various countries, and applied solely to research on the interrelationships of the structure and properties of metals and alloys.Each science must have its own subject and its own method of research. Certainly, all specialists will agree that metals and alloys, including their solid solutions, mechanical mixtures, and metallic compounds, form the subject of "physical metallurgy" or "physical chemistry of metals." The aim of this science. is to produce a theory and to elucidate the experimental relationships which ought finally to make it possible to calculate quantitatively alloys Of given properties for any working conditions and parameters.With regard to the methods of research on metals and alloys, we assume that "physical metallurgy" may properly employ any theoretical and experimental methods which will help to solve its basic problems. The experience of the last few decades has shown that among the experimental methods a leading position is occupied by the physicochemical analysis of metal systems developed by N. S. Kurnakov, that is to say, the systematic investigation of the phYSical properties of alloys as a function of he variation of their chemical composition and phase composition. This method has also been employed for investigating the interrelationship of the structure and properties of alloys at different temperatures and pressures (see E. M. Savitsky, The Influence of Temperature on the Mechanical Properties of Metals and Alloys, Stanford University Press, 1961). The "physical chemistry of metals" makes extensive use of physicochemical analysis. The science of metals and alloys absorbs all the achievements of the exact fundamental sciences, primarily physics and chemistry. It may even be said more precisely:The "physical chemistry of metals" or "physical metallurgy" is the synthesis of the physics of metals and the chemistry of metal alloys. The distribution and energy of electrons is the basic factor determining the crystal structure and all the properties of metals and alloys. The main problems which have to be solved in the framework of these sciences are the following: the electronic structure and nature of the interatomic bond in metal crystals, solid solutions of metals and metallic compounds, the development of methods for the quantitative measurement of the value of the interatomic forces with variation in the fundamental parameters...

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“…According to the results of [232] the activation energy of niobium oxides in pure oxygen is aboutl 0 kcal/mole at 500-600°C.…”

Section: Interaction With Oxygenmentioning

confidence: 98%

Physical Metallurgy of Refractory Metals and Alloys

Savitskii¹,

Burkhanov²

1995

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“…A study by Bridges and Fassell (1956) shown that the oxide formed on niobium in air at 473 K (200°C) is adherent and prevents further oxidation (Fansteel, 1945). They also referred to works that found that niobium obeys the parabolic rate law from 473 to 548 K (200-275°C) (Phelps et al, 1946;Gulbransen and Andrews, 1949;Gulbransen and Andrews, 1950).…”

Section: Review Of Literature Datamentioning

confidence: 99%

Review of oxidation of Nb-1Zr

DiStefano¹

1989

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A major objective of the SP-lOO Program Nuclear Assembly Test is to demonstrate the performance of a full-scale nuclear subsystem of a lOO-kWe space nuclear power supply. The test will be run in a large vacuum chamber to protect the Nb-lZr components from oxidation during operation. Much information about the oxidation of niobium and Nb-lZr alloy already exists, and previous work in this area is reviewed. Oxidation of Nb-lZr can proceed by solution, internal oxidation, and/or film formation. At temperatures up to about 650 K (377°C), oxidation generally follows a parabolic rate law because of the formation of protective oxide(s). At higher temperatures, oxidation becomes linear, but results are extremely sensitive to pressure and other system variables. Results obtained by several investigators could not be predicted using empirical equations developed by one investigator relating the increase in oxygen concentration to pressure, temperature, time, and specimen thickness. Additional data are required to provide more reliable guidelines for system operation that will protect against catastrophic effects.

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“…Figure 26 shows an example of the specimen curvature from this set. Figures 27,28,29,and 30 show the reproducibility of the oxidation, cooling, dissolution, and annealing measurements respectively for specimens oxidized for 240 minutes. Figure 31 shows an example of the corresponding curvatures for this set of speci mens.…”

Section: Resultsmentioning

confidence: 99%

“…At 900°C the rate goes through a second maxi mum, experiences a slight drop, goes through a minimum around o o 1000 C and then increases again to 1400 C. This second reversal in the oxidation rate was usually associated with the transformation of niobium pentoxide from a low temperature to a high temperature form; called M-T or ) Y-«. The first reversal in the oxidation rate has been the subject of investigation of many researchers (12,24,26,29,48,50,55). The strongest evidence between oxidation rate and possible causes appears to be the correlation between the reversal in the oxidation rate and the change in the innermost oxide from NbOg to NbO as reported by Doyle (12).…”

Section: Oxidation/temperature Relationshipsmentioning

confidence: 97%

The effect of stress on the low-temperature oxidation of niobium

Weirick

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High Pressure Oxidation of Niobium

Cited by 34 publications

References 4 publications

Physical Metallurgy of Refractory Metals and Alloys

Physical Metallurgy of Refractory Metals and Alloys

Review of oxidation of Nb-1Zr

The effect of stress on the low-temperature oxidation of niobium

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