Silica spheres, mercury intrusion

Figure 2. Distribution of pore volume for silica spheres I, II, and III by mercury intrusion.

The monodisperse non aggregated silica sphere slabs undergo only intrusion during mercury porosimetry experiments. Due to the very compact arrangement of the spheres, the pore volume Kng is very small (table 2). Ing increases when the size of the spheres increases from 8 to 206 nm. 

The results with the slabs of monodisperse non aggregated silica spheres (of the same size range than the xerogels and aerogels) which undergo only intrusion during mercury porosimetry implies that the particles need to be aggregated so that the compaction mechanism takes place... 

Mercury Intrusion Experiments with Silica Spheres. These silica spheres (S980 G1.7 from Shell) were not examined in the same detail as were the other silica samples, but the photographs are included because they illustrate the effect of mercury intrusion on the integrity of the solid. These particular spheres have a typical pore volume of 1 cm3/g and a pore diameter of 60 nm. The particles are also much larger than the Sorbsil materials (1.7 mm in diameter, compared to 40 to 60 pm for the Sorbsil materials). 

Figure 7. Effect of mercury intrusion on silica spheres (Shell). Top, starting material and bottom, material after mercury intrusion (no attempt was made to remove the mercury).

Mercury Intrusion Experiments with Silica Spheres... 

It has been found that models for the structure of sol-gel silica spheres, constructed foom spin density and spin-spin relaxation time images, give rise to good predictions for tiie point of separation of mercury intrusion and retraction curves, and the level of mercuiy entrapment, found for experimental porosimetry data for the same material. This finding suggests that the MR images contain sufficient information to determine the level of mercury entrapment. Hence, this result supports the view that mercury intrusion and retraction within this material is determined by macroscopic (0.01-1 mm) heterogeneities in the spatial distribution of porosity and pore size. 

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