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

Sarikaya Y., ÖNAL M., Ada K.

JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, cilt.107, sa.2, ss.419-423, 2012 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 107 Sayı: 2
  • Basım Tarihi: 2012
  • Doi Numarası: 10.1007/s10973-011-1922-x
  • Dergi Adı: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.419-423
  • Anahtar Kelimeler: Adsorption, Alumina, Porosity, Sintering thermodynamics, BOILING AQUEOUS-SOLUTION, SURFACE-AREA, POWDER, BENTONITE, KINETICS, SULFATE, ENERGY, UREA
  • Ankara Üniversitesi Adresli: Evet

Özet

The specific micro- and mesopore volumes (V) of alumina compacts fired between 900 and 1250 A degrees 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 A degrees C before sintering. Also, an arbitrary Gibbs energy (Delta G (a) A degrees) of sintering was calculated for each temperature using the K (a) value. The graph of ln K (a) versus 1/T and Delta G (a) A degrees versus T were plotted, and the real enthalpy (Delta HA degrees) and the real entropy (Delta SA degrees) of sintering were calculated from the slopes of the obtained straight lines, respectively. On the contrary, real Delta GA degrees and K values were calculated using the real Delta HA degrees and Delta SA degrees values in the Delta GA degrees = -RT lnK = 165814 - 124.7T relation in SI units.