D20 - High-intensity two-axis diffractometer with variable resolution


Stroboscopic acquisitions on D20 were used for rheologic investigations of orientation of flat or rod like particles (clays, hematite), suspended in water, at laminar flow, turbulent flow and with a shear gradient.

They effected dynamic studies at start and stop of flow in pipe flow geometry using a tube where the pumping direction changed every 10 s. In order to study the dynamics of disordering and realigning of Ni(OH)2 platelets after flow reversal, every second of the latter served as synchronisation signal for a cycle of 20 s containing 54 slices of 390 ms. After 17 cycles (6 min) the accumulated counting rate was sufficient to show the dynamic behaviour.

Ref.: Brown A.B.D., Rennie A.R. - Monodisperse colloidal plates under shear, Physical Review E 62, 851-862 (2000)