Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1626660 | Journal of Alloys and Compounds | 2007 | 6 Pages |
The cylindrical compacts with the diameter of 14 mm were prepared under 32 MPa of an alumina powder having agglomeration degree of 80% and maximum surface area of 81 m2 g−1 after calcination at 900 °C for 2 h. Each compact was fired isothermally at a different temperature between 950 and 1150 °C for 2 h. The rate constant for each temperature was obtained from the application of the zero-order reaction rate model on the surface area measurements after sintering. Arrhenius equation for the sintering was obtained in the form: k = (8.09 × 106 m2 mol−1 s−1) exp (−187 643 J mol−1/RT). Transition state theory was applied to the sintering and thermodynamic parameters of the activation were calculated. The relation of these parameters in SI units can be summarized in the forms: ΔH# = 178 643 − 8.314T, ΔS# = −73.6 − 8.314 ln T, and ln K# = −ΔG#/RT = −(ΔH# − TΔS#)/RT = −21 487/T − ln T − 7.853, where ΔG#, ΔH#, ΔS# and K# are the Gibbs free energy, enthalpy, entropy, and equilibrium constant of activation.