Pore-boundary separation

For pore/boundary separation, two extreme cases can be considered ... 

Figure 11.2 delineates the calculated conditions of pore/boundary separation (Eqs (11.15) and (11.16)) together with the equal mobility line on a grain size versus pore size plane in log scale when pores move by surface diffusion. The minimum grain size G for pore/boundary separation is determined to be the point where the two lines of pore/boundary separation conditions converge. For surface-diffusion controlled boundary movement, G is expressed as... 

To reduce G [oc (Z>A)/ /Z)/Xs)], DJDi and Yi,Iys must be reduced. With the reduction of G, however, the region of pore/boundary separation is enlarged and pore/boundary separation can easily occur. An optimization is needed as always. 

Describe possible techniques (as many as possible) to suppress pore/ boundary separation during sintering. 

An enhanced understanding of the important role of the interface anisotropy on the microstructure evolution also raised a question on the conventional approach to the pore-boundary separation problem. It was noted that pores should remain at the... 

Pore-boundary separation behavior during sintering of pure and Bi20j-doped ZnO ceramics./. Am. Ceram. Soc., 84 (6), 1398-2300. 

Figure 3.10. Sintering map showing the grain size depending on the densification [HAR 84], On the left principle of the map on the right for complete densification to be possible, the sintering trajectory must not cut the hatched pore-boundary separation area...

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