A Free Energy Approach for Deriving Rate Equations for Diffusion-controlled Sintering

Abstract

Diffusion-controlled sintering is discussed from thermodynamic and kinetic points of view and sintering rate equations are derived by regarding the overall change in the free energy of a material being sintered as driving force of diffusion. This new approach is much simpler than the conventional one and it enables us to derive the rate equations without knowing local chemical potential fields. The kinetics of the diffusional shape change of pores in the sintering aggregate is also formulated. On the basis of the derived rate equations, new criteria are proposed for the change in sintering stages. The results of the present theoretical analyses are compared with previous experimental results. Reasonable agreement between them is found.