Surface Oxidation Kinetics of an a-Si3 N4 and an Amorphous Si3 N4 Powder

ABSTRACTSurface oxidation kinetics of an a-Si3 N4 submicron size and an amorphous nano-size powder have been studied using x-ray photoelectron spectroscopy (XPS) and Bremsstrahlung-excited Auger electron spectroscopy (AES). The samples were oxidized by heating in air at temperatures between 850°C and 1000°C. The oxide thickness for each heating time and temperature was determined both from the relative 0 Is and N Is XPS peak intensities and from the Si02 and Si3 N4 Si KLL peak intensities. In each case, there was a good agreement between the oxide thickness value calculated from the XPS data and that obtained from the AES data. At these temperatures, oxidation followed a linear rate law. Activation energies of 15±1 kcal/mole and 27±1 kcal/mole were measured for the a-powder and the amorphous powder, respectively.

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Effects of α-silicon nitride powder processing on surface oxidation kinetics

Journal of Materials Research ◽

10.1557/jmr.1993.3168 ◽

1993 ◽

Vol 8 (12) ◽

pp. 3168-3175 ◽

Cited By ~ 13

Author(s):

Pu Sen Wang ◽

Subhas G. Malghan ◽

Stephen M. Hsu ◽

T.N. Wittberg

Keyword(s):

Photoelectron Spectroscopy ◽

Electron Spectroscopy ◽

Powder Processing ◽

Surface Oxidation ◽

Oxide Thickness ◽

Heating Time ◽

Linear Rate ◽

X Ray ◽

Surface Areas ◽

Silicon Nitride Powder

The oxidation of two α–Si3N4 powders has been studied using x-ray photoelectron spectroscopy (XPS) and Bremsstrahlung-excited Auger electron spectroscopy (AES). These two powders had comparable specific surface areas but were produced by different methods. The powders were oxidized by heating in air at temperatures between 850° and 1000 °C. The oxide thickness for each heating time and temperature was determined both from the relative O 1s and N 1s peak intensities and from the relative SiO2 and Si3N4 Si KLL peak intensities. In each case, the oxide thickness calculated from the XPS data was systematically higher than those determined from the AES data. This difference may be due to uncertainties in the data analysis procedures. The oxidation of each powder followed a linear rate law for these temperatures. On one of the powders, the XPS data showed evidence of oxynitride formation. Analysis with thermal decomposition mass spectroscopy also showed that much more hydrogen was evolved from this particular powder, particularly at temperatures >700 °C. These differences in bulk impurity levels are believed to be responsible for the differences in the activation energies for oxidation which were measured to be 104 ± 22 kJ/mol and 62 ± 4 kJ/mol for these two powders.

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Surface oxidation kinetics of SiC powders in wet and dry air studied by x-ray photoelectron spectroscopy and bremsstrahlung-excited Auger electron spectroscopy

Surface and Interface Analysis ◽

10.1002/sia.1598 ◽

2003 ◽

Vol 35 (10) ◽

pp. 773-778 ◽

Cited By ~ 11

Author(s):

Thomas N. Wittberg ◽

Pu Sen Wang ◽

Stephen M. Hsu

Keyword(s):

Auger Electron Spectroscopy ◽

Photoelectron Spectroscopy ◽

Oxidation Kinetics ◽

Electron Spectroscopy ◽

Auger Electron ◽

Surface Oxidation ◽

X Ray ◽

Dry Air ◽

Kinetics Of

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Gas-Phase Anionic Metal Clusters are Model Systems for Surface Oxidation: Kinetics of the Reactions of Mn– with O2 (M = V, Cr, Co, Ni; n = 1–15)

The Journal of Physical Chemistry A ◽

10.1021/acs.jpca.0c10103 ◽

2021 ◽

Vol 125 (10) ◽

pp. 2069-2076

Author(s):

Brendan C. Sweeny ◽

David C. McDonald ◽

Nicholas S. Shuman ◽

Albert A. Viggiano ◽

Juergen Troe ◽

...

Keyword(s):

Gas Phase ◽

Oxidation Kinetics ◽

Metal Clusters ◽

Surface Oxidation ◽

Model Systems ◽

Kinetics Of

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Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

Rubber Chemistry and Technology ◽

10.5254/1.3542149 ◽

1960 ◽

Vol 33 (2) ◽

pp. 335-341

Author(s):

Walter Scheele ◽

Karl-Heinz Hillmer

Keyword(s):

Activation Energy ◽

Physical Properties ◽

Chemical Kinetics ◽

Kcal Mole ◽

First Order ◽

Equilibrium Swelling ◽

Kinetics Of ◽

Kinetics Of Vulcanization ◽

Limiting Value ◽

Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

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Insect blood-brain barrier: a radioisotope study of the kinetics of exchange of a liposoluble molecule (n-butanol)

Journal of Experimental Biology ◽

10.1242/jeb.64.1.119 ◽

1976 ◽

Vol 64 (1) ◽

pp. 119-130

Author(s):

M. V. Thomas

Keyword(s):

Activation Energy ◽

Temperature Sensitivity ◽

Nerve Cord ◽

Previous Investigation ◽

Time Course ◽

Kcal Mole ◽

Similar Time ◽

Kinetics Of ◽

Butanol Concentration ◽

Good Agreement

About 90% of the butanol uptake by the cockroach abdominal nerve cord washed out with half-times of a few seconds, in good agreement with an electrophysiological estimate, and the temperature sensitivity suggested an activation energy of 3 Kcal mole-1. The remaining activity washed out far more slowly, with a similar time course to that observed in a previous investigation which had not detected the fast fraction. Its size was similar to the non-volatile uptake, and was considerably affected by the butanol concentration and incubation period. It apparently consisted of butanol metabolites, which could be detected by chromatography.

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