An indirect model for sintering thermodynamics

Abstract

A model was proposed and used to calculated the changes in enthalpy (∆Ho), entropy (∆So);and Gibbsenergy (∆Go), as well as equilibrium constant (K) relating to the sintering of alumina compacts. Speci c nanoporevolume (V) of the compacts was assumed as a thermodynamic variable. A hypothetical equilibrium constant (Kh)and corresponding Gibbs energy (∆Goh) were calculated depending on theVvalue measured after each sintering. Thethermodynamic relationships with the SI units were respectively evaluated for the initial-stage (i) sintering between1000 and 1200◦C and nal-stage (f) sintering between 1200 and 1600◦C in the following form: ∆Goi=RTlnKi=∆HoiT∆Soi= 161;042110:5Tand ∆Gof=RTlnKf= ∆HofT∆Sof= 39;00047:5T