The sintering of solid metal particles

There is a qualitative distinction between these two types of mass transfer. In the case of vapour phase transport, matter is subtracted from the exposed faces of the particles via dre gas phase at a rate determined by the vapour pressure of the solid, and deposited in the necks. In solid state sintering atoms are removed from the surface and the interior of the particles via the various diffusion vacancy-exchange mechanisms, and the centre-to-cenU e distance of two particles undergoing sintering decreases with time. 

In die operation of die first source, the driving force for sintering is the difference in curvature between the neck and the surface of the sphere. The curvature force A l, is given by 

The second, the grain boundary driving force, Ky, is given by 

The differential equations for neck growth by these four titechanisms are (Ashby, 1974) 

Both these diffusion controlled and the vapour phase transport processes may be described by tire general equation 

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