During Liquid Metal Injection (LMI) the fusible alloy intrudes and fills the connected pore network. The degree of percolation depends on the critical pore throat diameter in the porous medium. The minimum pore throat diameter which can be filled depends on the injection pressure, following the Washburn equation. After the desired injection pressure is reached, the sample is cooled down under pressure and the metal solidifies in the pores. The following BIB-SEM investigation allows interrogating the 3D pore network.
Characterization of the connected pore network at nanometer resolution on a representative sample scale.
Using this LMI method we provide, next to the standard BIB-SEM image data, the following:
3D Pore connectivity
Porosity and permeability assessment
LMI resembles conventional Mercury Intrusion Porosimetry (MIP) and therefore we can evaluate MIP data as we visualize what part of the pore space is actually being filled with the liquid metal. Moreover, we can investigate the pore space between the cracks and correct for core damage.
Permeability estimation can be obtained relatively easy by using the capillary tube model, as we know the effective porosity and the percolation threshold from the image data.
This LMI followed by BIB-SEM methodology can be applied on any fine-grained geological material or nano-material with sub-millimeter pore throats.