Journal of Thermal Analysis and Calorimetry

, Volume 107, Issue 2, pp 419–423 | Cite as

An indirect thermodynamic model developed for initial stage sintering of an alumina compacts by using porosity measurements

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Abstract

The specific micro- and mesopore volumes (V) of alumina compacts fired between 900 and 1250 °C for 2 h were determined from nitrogen adsorption/desorption data. The V value was taken as a sintering equilibrium parameter. An arbitrary sintering equilibrium constant (K a) was estimated for each firing temperature by assuming K a = (V i − V)/V, where V i is the largest value at 900 °C before sintering. Also, an arbitrary Gibbs energy (ΔG a °) of sintering was calculated for each temperature using the K a value. The graph of ln K a versus 1/T and ΔG a ° versus T were plotted, and the real enthalpy (ΔH°) and the real entropy (ΔS°) of sintering were calculated from the slopes of the obtained straight lines, respectively. On the contrary, real ΔG° and K values were calculated using the real ΔH° and ΔS° values in the ΔG° = −RT lnK = 165814 − 124.7T relation in SI units.

Keywords

Adsorption Alumina Porosity Sintering thermodynamics 
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Notes

Acknowledgements

The authors are grateful to the Scientific and Technical Research Council of Turkey for supporting this study under the project TÜBİTAK-106T056.

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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2011

Authors and Affiliations

  1. 1.Department of Chemistry, Faculty of ScienceAnkara UniversityTandoğanTurkey
  2. 2.Department of Chemistry, Faculty of Arts and SciencesKırıkkale UniversityKırıkkaleTurkey

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