D3 Porosimetry and Density

Topic

The experimental determination of a ceramic's density and porosity—the aim of this model—begins with the Archimedes method. Because this method involves weighing the specimen both in air and while submerged in a liquid, a single measurement yields both the specimen's apparent density and its open porosity—that is, the fraction of pores interconnected with each other and with the specimen's exterior.

Within the open porosity measured by the Archimedes method, the Washburn equation—applied via mercury porosimetry, which forces mercury into the pores under pressure—determines a detail that the Archimedes method alone cannot provide: the pore size distribution. A higher pressure requirement for mercury to enter a pore indicates a smaller pore size; by measuring the pressure at which mercury enters each fraction of the pore volume, one can determine which fraction of the open porosity corresponds to large pores and which to small ones.

Consequently, the apparent density, open porosity, and pore size distribution measured and determined by this model do not stand in isolation. These three parameters serve as the specific inputs for another model within the same suite—one that describes the porosity and relative density of the ceramic.

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