Controlled shape formation of particles in a stirred media mill

• Applicants: Dr. Cornelia Damm; Professor Dr.-Ing. Wolfgang Peukert
• Subject Area: Mechanical Process Engineering
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442641322

The objective is to better understand process-structure relationships for the controlled shape formation in a stirred media mill. The research focus is on the shape control of different material systems (metals, polymers and glasses) under specific mechanical stress between grinding beads as well as suitable characterization of the accompanied shape change. The kinetics of the controlled shape formation of different material systems is controlled by the process as well as material function. The material function is defined by the choice of material systems (Cu, Al, polystyrene, borosilicate glass, soda-lime glass), while the process function can be easily varied by parameters such as agitator speed, grinding media size and density as well as process time. Therefore a study of various process function parameters should allow a deeper understanding of the stress of different material systems in a stirred ball mill. Micromechanical investigations on single particles are carried out by in-situ micromanipulation in a scanning electron microscope. The targeted application of single particles with an in-situ SEM micromanipulator has already been carried out for a variety of material systems and the methodology has been established. All experimental micromanipulation data is validated by FEM simulations. In addition, the method spectrum is extended by a promising method for the characterization of large numbers of single particles with varying morphologies (flow cytometry). This method relies on single particle interaction with a focused laser beam. As a result of the size- and shape-dependent forward and lateral scattering of the individual particles, it is possible to deduce the aspect ratio from the measured scattering signal. In addition, SEM images of the particulate systems are recorded and evaluated in terms of thickness and lateral dimensions. The combination of both methods is used for validation and opens up new ways of determining the shape formation in stirred media mill. Additionally, important information can be gathered via ICP OES, FTIR and XRD with regard to chemical composition, structure as well as changes of the material systems due to the processing in a stirred media mill. Finally, the knowledge that is gained in this project will be transferred to glasses with tailor-made compositions for applications such as electrochemical storage.

• DFG Programme: Research Grants
• Major Instrumentation: Durchflusszytometer
• Instrumentation Group: 3500 Zellzähl- und Klassiergeräte (außer Blutanalyse), Koloniezähler