Kinetics analysis of mullite formation reaction at high temperatures

✍ Scribed by Yun-Mo Sung

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 184 KB
• Volume: 48
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/s1359-6454(00)00032-x

✦ Synopsis

AbstractÐA detailed kinetics analysis was performed on the mullite (3Al 2 O 3 Á2SiO 2 ) formation reaction occurring at high temperatures ranging from H1600 to 18008C. The counterdiusion model of Al 3+ and Si 4+ ¯uxes was used to derive the kinetics equation of the mullite formation reaction. From the parabolic kinetics between the thickness of the mullite layer and time, the reaction rate constant (k ) for the mullite formation was determined to be a function of the average diusion coecient of Si 4+ ions. This kinetics equation can be used to estimate the mullite formation at any temperature. By substituting previous experimental data into the present kinetics equation, average diusion coecient values of Si 4+ ions in the mullite layer were calculated and these values are in good agreement with the diusion coecient values calculated using Aksay's interdiusion equation for mullite formation. The activation energy values for the diusion of the Si 4+ ions were estimated to range from 730 to 780 kJ/mol, which are close to those obtained from previous diusion and creep experiments.