Sintering by vapour phase transport

The dependence of the thickness of the neck on the time of sintering, t, is given by 

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The process of sintering by vapour phase transport is probably important to the growth of single crystals of solids from polycrystalline samples in a closed system, where the vapour species are the transporting gas, which may have the same or different chemical composition from die solid. An example where... 

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. 

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