| Modeling Oxidation Kinetics of SiC-Containing Refractory Diborides |
Jan 2012 |
13 pages |
| Authors:
T A Parthasarathy; R A Rapp; M Opeka; M K Cinibulk; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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 | Experimental data on the oxidation kinetics of SiC-containing diborides of Zr and Hf in the temperature regime of 1473 2273 K are interpreted using a mechanistic model. The model encompasses counter-current gas diffusion in the internal SiC depleted zone, oxygen permeation through borosilicate glass channels in the oxide scale, and boundary layer evaporation at the surface. The model uses available viscosity, thermodynamic and kinetic data for boria, silica, and borosilicate ... |
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| A Model for Transitions in Oxidation Regimes of ZrB2 |
Jul 2008 |
13 pages |
| Authors:
T A Parthasarathy; R A Rapp; M Opeka; R J Kerans; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| A mechanistic model that interprets the transition in oxidation behavior of zirconium diboride as the temperature is varied from 600-deg C to 2500-deg C is presented. Available thermodynamic data and literature data for vapor pressures, oxygen permeability in boria, and viscosity of boria were used to evaluate the model. Three regimes and the temperatures of transition between them were identified. In the intermediate temperature regime, viz., 1000-deg C to 1800-deg ... |
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| A Model for the Oxidation of Refractory Diborides (Preprint) |
May 2007 |
25 pages |
| Authors:
T A Parthasarathy; Ronald J Kerans; M Opeka; UES INC DAYTON OH
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| Hypersonic applications require materials that can withstand very high temperatures. Refractory diborides appear to be the most promising candidates for these applications, from the standpoint of resistance to oxidation and evaporative loss. In this work, a mechanistic model is presented that predicts the oxidation behavior of diborides of Zr, Hf and Ti. Using available thermodynamic data and literature data on vapor pressures, good correspondence is obtained between theory and experiments ... |
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| A Model for the Oxidation of ZrB2, HfB2 and TiB2 (Postprint) |
Mar 2007 |
15 pages |
| Authors:
T A Parthasarathy; R A Rapp; M Opeka; R J Kerans; UES INC DAYTON OH
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| A mechanistic model that interprets the oxidation behavior of the diborides of Zr, Hf and Ti in the temperature range of 1000-1800 deg C was formulated. Available thermodynamic data and literature data for vapor pressures and diffusivities were used to evaluate the model. Good correspondence was obtained between theory and experiments for weight gain, recession and scale thickness as functions of temperature and oxygen partial pressure. At temperatures below about ... |
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