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

Abstract: 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.