On the Final Stage in Pressure Sintering Process

Abstract

The densification rate equation on the final stage in pressure sintering is derived on the basis of a theory of diffusional creep developed by Nabarro and Herring. The stress distribution in a powder compact is regarded to be the same as the stress distribution in a thick walled spherical shell under an external pressure. The resultant densification rate is expressed by dρ/dt=(9/2) (40 DΩ/kTd2)(1-ρ)(p2-p1), where ρ is the relative density and p2-p1 is the pressure difference between outside and inside of the hollow sphere. The rate equations are also obtained taking into consideration the effects of the surface energy and the enclosed gas pressure.