Applications of the zero-order reaction rate model and transition state theory on the intra-particle sintering of an alumina powder by using surface area measurements

Sarikaya Y., Ada K., ÖNAL M.

JOURNAL OF ALLOYS AND COMPOUNDS, cilt.432, sa.1-2, ss.194-199, 2007 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 432 Sayı: 1-2
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1016/j.jallcom.2006.05.100
  • Dergi Adı: JOURNAL OF ALLOYS AND COMPOUNDS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.194-199
  • Anahtar Kelimeler: activation parameters, alumina, sintering rate, surface area, transition state, BOILING AQUEOUS-SOLUTION, AGGLOMERATED POWDERS, ULTRASONIC VELOCITY, ACTIVATION-ENERGY, CERAMIC POWDERS, PARTICLE-SIZE, UREA REACTION, KINETICS, REDUCTION, PRECURSOR
  • Ankara Üniversitesi Adresli: Evet

Özet

The cylindrical compacts with the diameter of 14mm were prepared under 32MPa of an alumina powder having agglomeration degree of 80% and maximum surface area of 81 m(2) g(-1) after calcination at 900 degrees C for 2 h. Each compact was fired isothermally at a different temperature between 950 and 1150 degrees 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 x 10(6) m(2) 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: Delta H-# = 178 643 - 8.314T, Delta S-# = -73.6 - 8.314 ln T, and ln K-# = -Delta G(#)/RT = -(Delta H-# - T Delta S-#)/RT= -21 487/T - ln T - 7.853, where Delta G(#), Delta H-#, Delta S-# and K-# are the Gibbs free energy, enthalpy, entropy, and equilibrium constant of activation. (c) 2006 Elsevier B.V. All rights reserved.