X-Ray Computed Tomography specifically adapted for monitoring of dynamic processes in material science and chemistry
M. Salamon 1*, S. Reisinger 1, T. Schlechter 1 M. Schmitt 1, T. Hofmann 1, N.Uhlmann 1,
S. Schug2, W. Arlt2, L. Fahlbusch3, M. Arzig3, P. Wellmann3
1 Fraunhofer Development Centre for X-ray Technology (Flugplatzstr. 75, 90763 Fürth, Germany)
2 Institute of Separation Science and Technology, University Erlangen-Nuremberg, Erlangen, Germany
3 Crystal Growth Lab, University Erlangen-Nuremberg, Erlangen, Germany
*Underline the corresponding author and reference multiple institutions with numbers
X-ray computed tomography (CT) is an established method in non-destructive testing / evaluation (NDT / NDE) applications. A wide range of CT systems is available to the market distinct mainly by resolution properties. The process X-ray tomography application requires for an adaption of the process device which in some cases can be mounted on the rotation stage of the standard CT apparatus. Most representative examples are compact fatigue testing devices providing multiaxial forces to the tensile specimen encapsulated in a mostly X-ray transparent housing. This procedure is usually applied to relatively small and isolated samples. For processes that cannot be measured in an isolated environment, due to their size or other boundaries application specific CT systems can be developed using a large variety of X-ray components available on the market. In this contribution the Fraunhofer Development Centre for X-ray Technology (EZRT) shows application specific solutions realized in the past years for process monitoring in material science and chemistry. One focus of the contribution is the CT of packed distillation columns applied for the investigation of the fluid dynamics and transportation processes in different packing systems at the Institute of Separation Science and Technology, University of Erlangen-Nürnberg. Fluid dynamic parameters in distillation columns (like interfacial area, liquid hold-up and liquid film thickness on the packing or between two liquid phases) can be directly estimated from the recorded CT images of a packing cross section at different height positions along the column in operation. A segmentation process allows for a quantitative evaluation of the fluid behaviour corresponding to the packaging. The CT system is adapted to scan a chromatography or distillation column in its vertical orientation using a horizontally rotating X-ray gantry setup allowing for gravity affected measurements relevant in e.g. low pressure fluid systems. The setup allows for versatile applications with a CT scan rate of 1 Hz at a maximum resolution down to 70 microns for objects between 50 and 200 mm. This technique replaces today the commonly applied medical CT for such kind of experiments. Another presented example for a process adapted CT setup provides an insight into the Physical Vapor Transport (PVT) process at 2200°C allowing in- situ observation of the growth of SiC bulk crystals. The actual results achieved at the Crystal Growth Lab, University of Erlangen-Nürnberg by adaption of an X-ray tomography setup to a customized growth chamber setup will be presented and an outlook on the development tasks will be given.
Keywords X-ray tomography, 4D-CT, Fluid dynamics, Crystal growth
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