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Characterization of pore space using “Wood`s metal”

Method:


Pores and holes in porous materials can be characterized by intrusion of alloys such as „Wood`s Metal“ (50 Bi, 25 Pb, 12.5 Sn and 12.5 Cd in wt%; melting point of 78°C) or „Rose`s metal“ (50 Bi, 25 Pb, 25 Sn in wt%; melting point of 94°C). At a pressure of 550 bar connective pores with equivalent diameters as small as 20 nm are intruded with the molten alloy. Sample size of 5 mm; temperatures typically up to 120°C. After cooling polished sections are prepared and analyzed using an electron microscope.

Back scattered electron image of altered phenocrysts of Hornblende from Unzen volcano. Connective pores appear white. In the rim of the phenocrysts layer silicates (chlorite) are visible.

Applications:

The method yield supplementary information to Hg-porosimetry and tomography. Pathway for fluids in rocks and other ceramic materials can be determined.

Literature:

 

Dultz, S., Behrens, H., Simonyan, A., Kahr, G., Rath, T.  (2006): Determination of porosity and pore connectivity in feldspars from soils of granite and saprolite, Soil Science 171 (9) , pp. 675-694