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Oxidation mechanism of C in MgO-C refractory bricks

Sadrnezhaad, S. K ; Sharif University of Technology | 2006

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  1. Type of Document: Article
  2. DOI: 10.1111/j.1551-2916.2005.00863.x
  3. Publisher: 2006
  4. Abstract:
  5. Kinetics of oxidation of MgO-C refractory bricks containing 14.3% graphite, 80.9% magnesia, and 4.8% phenolic resin is investigated comprehensively. Effect of temperature and grain size distribution on the rate of oxidation of graphite is evaluated by application of a mathematical model developed on the basis of shrinking core/progressive conversion regime to the gas-solid processes involved. Incorporation of the experimental data into the mathematical model indicates that a mixed controlling mechanism governs the oxidation rate. Three activation energies were recognized: (a) 68 kJ/mol for chemical adsorption of gas on the surface of the graphite flakes, (b) 22 kJ/mol for pore diffusion of the gases within the decarburized layer, and (c) 140 kJ/mol for internal diffusion of the reactants toward the active reaction sites. The first process was influential at all temperatures, the second was confined to the temperatures above 800°C and the third was attributed to the temperatures lower than 800°C. Empirical data indicated a much lower weight loss rate at temperatures lower than 800°C. © 2006 The American Ceramic Society
  6. Keywords:
  7. Grain size and shape ; Graphite ; Mathematical models ; Oxidation ; Phenolic resins ; Oxidation rate ; Progressive conversion ; Refractory bricks ; Magnesia refractories
  8. Source: Journal of the American Ceramic Society ; Volume 89, Issue 4 , 2006 , Pages 1308-1316 ; 00027820 (ISSN)
  9. URL: https://ceramics.onlinelibrary.wiley.com/doi/10.1111/j.1551-2916.2005.00863.x