Compact nanocrystalline soft magnets using Field-Assisted Sintering

• Applicant: Professor Dr.-Ing. Christoph Broeckmann
• Subject Area: Materials in Sintering Processes and Generative Manufacturing Processes
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 500498139

This applied transfer project is based on a successfully completed DFG project with the Priority Programme SPP 1959, which studied the simulation of temperature distribution and grain growth during field-assisted sintering technology (FAST/SPS). The know-how obtained in the completed project will be transferred to an industrial application in the applied project. This project will start at technology readiness level (TRL) 4. The developed numerical model will be the fundamental basis for further developments in the application-oriented field of manufacturing compact nanocrystalline soft magnets. In this transfer project, FAST/SPS will be used for the processing of compact nanocrystalline soft magnets (Finemet Fe73.5Cu1Nb3Si15.5B7 (at.%)) in order to produce soft magnetic components with geometric diversity, high power density, and low hysteresis and eddy current losses. The compact design makes the typical plastic housing of the commercial wounded cores unnecessary which allows the operation of the components at up to 300°C, instead of 150°C. These improvements are currently of extraordinary interest for the miniaturization and the efficient energy conversion in the field of soft magnets. The compacted materials should be able to be manufactured into different inductive components depending on their magnetic permeabilities, so that a wide range of applications is possible. Preliminary investigations showed that the processing of amorphous flakes made from melt spun ribbons could help to achieve promising properties of the products, as the soft magnetic properties can be directly adjusted by selecting suitable flake sizes for manufacturing. However, the flakes with different size distributions could lead to completely different temperature distributions in the compaction process, which results in inhomogeneous microstructures. Therefore, to assure a homogenous temperature distribution within the required temperature window, the numerical simulation is necessary. The gained knowledge and the developed methods from the completed DFG project provide a solid basis for the processing of compact nanocrystalline soft magnetic components and the industrial application in this transfer project. With the further developed models, the conceptual ideas for the homogenization of the temperature distribution and the compaction of soft magnetic material during FAST/SPS will be tested in virtual, iterative simulation loops, and subsequently applied in the manufacture of the demonstrator. In this way, the currently well-employed trial and error methodology can be replaced by a straightforward procedure which saves time, recourses and cost.

• DFG Programme: Research Grants (Transfer Project)
• Application Partner: Magnetec GmbH
• Cooperation Partner: Professor Dr.-Ing. Thomas Weißgärber