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

• Published in: Journal of thermal analysis and calorimetry 2012-02, Vol.107 (2), p.419-423
• Main Authors: Sarıkaya, Y., Önal, M., Ada, K.
• Format: Article
• Language: English
• Subjects: Adsorption; Aluminum oxide; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Exact sciences and technology; General and physical chemistry; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Porosity; Sintering; Solid-gas interface; Surface physical chemistry; Thermodynamics
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-011-1922-x

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 (Δ G a ° ) of sintering was calculated for each temperature using the K a value. The graph of ln K a versus 1/ T and Δ G a ° versus T were plotted, and the real enthalpy (Δ H° ) and the real entropy (Δ S° ) of sintering were calculated from the slopes of the obtained straight lines, respectively. On the contrary, real Δ G° and K values were calculated using the real Δ H° and Δ S° values in the Δ G°  = − RT ln K  = 165814 − 124.7 T relation in SI units.