X-ray speckle-based dark-field imaging of water transport in porous ceramics

The evaluation of liquid transport through porous ceramics are of high importance in numerous applications of these materials, ranging from chemical and physical filters to biomaterials. We present a proof-of-concept of the capability of speckle-based Xray dark-field imaging (XDFI) for studying the water transport through porous materials with high sensitivity and sub-pixel resolution in a laboratory. Speckle-based imaging (SBI) takes advantage of a simple and flexible setup, with only an additional and inexpensive textured mask, to provide complementary multi-contrast images. Porous ceramic samples with different pore size ranges were imaged in dry and different pure water-saturated states, via an X-ray speckle-tracking setup. The retrieved darkfield images revealed a high sensitivity to (1) the pore size range and to (2) the local water saturation degree. Independently of the pore size range, the dark-field signal decreased upon water saturation. Compared with previously reported laboratory-scale XDFI results for water transport through porous materials, the speckle-tracking approach allows achieving higher temporal and spatial resolutions, thus broadening the range of (water) transport processes which can be investigated without using any contrast agent.