Investigation of paste flow using positron emission particle tracking

The extrusion of a model yield stress fluid imaged by MRI velocimetry

“…Another technique, known as Particle Image Velocimetry (PIV) [10], is an approach capable of revealing local velocity fields through the addition of reflective 'tracer' particles, unfortunately, slightly affecting the material properties, and the velocity is then carefully determined from successive images. Other techniques such as Laser Doppler Velocimetry (LDV) [11,12] and Positron Emission Particle Tracking (PEPT) [13] employ a direct measure of the velocity but once again are limited through this introduction of foreign particles to the material in question. Efforts to visualize the flow within non-transparent materials have been limited to invasive techniques such as opening up an extruder halfway through the process and cutting into the sample [3].…”

Velocity profiling inside a ram extruder using magnetic resonance (MR) techniques

“…Ultrasonic techniques have been used to map flow patterns at the extruder die entrance, during the flow of highly concentrated shear-thinning and shear-thickening suspensions (Oureiv and Windhab, 2003). Wildman et al (1999) used positron emission tomography to repeatedly track the displacement of a 2 mm particle in a ceramic paste flowing through a conical extrusion die, hence allowing the velocity field inside the extruder to be reconstructed.…”

Shaping ceramics by plastic processing

“…Visualisation experiments [61][62][63] confirmed that this assumption is a good description when pastes suitable for shape forming pass along a capillary. He recognised the link to soil mechanics in describing pastes using engineering plastic models and published 'Paste Flow and Extrusion' 58 with Bridgwater, which introduced a systematic framework for understanding paste structure and enabled design of paste processes.…”