Synchrotron CT images of hydrophobic sand: 1. wetting via droplet condensation and 2. water drop penetration time test

A device containing a Peltier element controlled by a Raspberry Pi was built in order to cool the granular material samples during the scans. The cooling induced condensation of water droplets on the surface of the grains. Sand and glass beads were used, both coated with a hydrophobic substance and uncoated. Scans were taken while the droplets grew and evolved to menisci between grains.

After the scans of the first experiment were done, a droplet of 50 microliter was placed on the surface of the some of the materials, a procedure that aims at measuring the hydrophobicity of a sample called Water Drop Penetration Time (WDPT) test.

The paper refered to in the "relations" section describes the variations of sample coating in more detail. The attached spreadsheet "00_desy_stacks" contains information about the samples material, order of scan and experiment of each stack.

In total, 11 samples were scanned, each between 8 and 18 times (amount of stacks). The uploaded files consist of 16 bit 3D-tifs.