Experiment

The specimens for this experiment were a sintered alumina ceramic frit typically used for filtration, with an advertised pore size less than 0.5 µm. Mercury intrusion porosimetry (MIP) measurements confirmed this value, and also gave an estimated total porosity of 26 %. The cylindrical specimens were approximately 50 mm in diameter and 6.4 mm thick. Each specimen was mounted into an acrylic annulus using an epoxy adhesive. After saturation, the mounted specimens were clamped between nearly identical cylindrical glass vessels, with each vessel having a volumetric capacity of approximately 250 mL. The setup for both the conductivity and the diffusion measurements is shown schematically in Fig. 1.

Figure 1: Cross section of both the conductivity cell apparatus(a) and the diffusion divide cell apparatus (b). The schematics depict the configuration of the two cylindrical glass vessels on either side of a mounted specimen. The system is sealed using rubber o-rings; the clamps are not shown. The apparatus differ only in the vertical platinum electrodes in the conductivity cell. The diameter of the specimen, the glass vessels, and the platinum electrodes are approximately 50 mm.

Once the specimens were affixed between the vessels, they were placed into an environmental chamber maintained at a temperature of 25 ºC. Both the conductivity and the diffusivity experiments were conducted in this chamber, with all measurements and sampling performed within the chamber.