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Title: | Initial stages of oxidation of near-stoichiometric titanium carbide at low oxygen pressures |
Authors: | Shabalin, I. L. Vishnyakov, V. M. Bull, D. J. Keens, S. G. Yamshchikov, L. F. Shabalin, L. I. |
Issue Date: | 2009 |
Publisher: | Elsevier BV |
Abstract: | A novel approach to the oxidation mechanism of near-stoichiometric TiC is presented. It is confirmed by consideration of solid-state chemical kinetics model and electron microscopy observations in parallel. At low oxygen pressures and moderate temperatures the initial step of the process is connected with the dissolution of oxygen and subsequent decomposition of oxygen-oversaturated oxycarbide, which ultimately results in the nucleation of oxide phase, in particular anatase, belike stabilised by residual carbon. An anatase-rutile transformation is concurrent with deeper carbon burn-off in the oxide scale, which sinters at higher temperatures. This mechanism shifts the process to a gas diffusion regime, governed by the scale permeability, but determined by solid-state diffusion that is reflected in the kinetics, as further temperature increase is accompanied by a decrease of the oxidation rate, so in general the process is characterised by the negative value of apparent activation energy. © 2008 Elsevier B.V. All rights reserved. |
Keywords: | GAS-SOLID REACTIONS KINETICS OXIDATION PHASE TRANSITIONS TRANSITION METAL ALLOYS AND COMPOUNDS ACTIVATION ENERGY DIFFUSION IN SOLIDS DISSOLUTION METAL RECOVERY OXIDATION OXIDE MINERALS OXYGEN PHASE TRANSITIONS SCALE (DEPOSITS) TITANIUM TITANIUM CARBIDE TITANIUM DIOXIDE TITANIUM OXIDES ANATASE - RUTILE TRANSFORMATIONS APPARENT ACTIVATION ENERGIES CHEMICAL KINETICS MODELS GAS DIFFUSIONS GAS-SOLID REACTIONS HIGHER TEMPERATURES INITIAL STAGES LOW OXYGEN PRESSURES MODERATE TEMPERATURES NEGATIVE VALUES OXIDATION MECHANISMS OXIDATION RATES OXIDE PHASE OXIDE SCALE OXYCARBIDE RESIDUAL CARBONS SOLID-STATE DIFFUSIONS TEMPERATURE INCREASE TRANSITION METAL ALLOYS AND COMPOUNDS TRANSITION METAL ALLOYS |
ISSN: | 0925-8388 |
DOI: | 10.1016/j.jallcom.2008.04.067 |
SCOPUS: | 61349202979 |
WoS: | 000264757200070 |
Appears in Collections: | Научные публикации, проиндексированные в SCOPUS и WoS |
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