SiCNFe Ceramics as Soft Magnetic Material for MEMS Magnetic Devices: A Mössbauer Study

Loss-Optimized Design of Magnetic Devices

Maximizing efficiency, power density, and reliability stands as paramount objectives in the advancement of power electronic systems. Notably, the dimensions and losses of magnetic components emerge as primary constraints hindering the miniaturization of such systems. Researchers have increasingly focused on the design of loss minimization and size optimization of magnetic devices. In this paper, with the objective of minimizing the loss of magnetic devices, an optimal design method for the winding structure of devices is proposed based on the coupling relationship between the loss prediction model and the design variables. The method examines the decoupling conditions between the design variables and the loss model, deriving optimized design closure equations for the design variables. This approach furnishes a technical foundation for the miniaturized design of miniature apparatuses incorporating magnetic components, offering a straightforward and adaptable design methodology. The finite element method simulation results and experimental measurement data verify the accuracy of the prediction of the proposed method and the validity of the optimal design theory of device loss.

Development of Inkjet Printable Formulations Based on Polyorganosilazane and Divinylbenzene

Within this work, ink formulations based on polyorganosilazane (OPSZ) and divinylbenzene (DVB) were developed to be processed by inkjet printing. The formulations were studied regarding their rheological, structural, and thermal properties. The rheological results show that the new formulations meet the requirements of the inkjet printer by showing both low viscosity (below 20 mPa∙s at printing temperature) and Newtonian flow behavior even at high shear rates. Additionally, the inks have surface tensions in the range of 21 to 26 mN/m2. First, printing experiments of single layers were successfully conducted and show that the developed formulations can be processed by inkjet printing. The inks were crosslinked by UV light and then pyrolyzed at 1100 °C resulting in a ceramic yield between 75 and 42%, depending on the ink formulation. The crosslinking behavior was studied via FTIR spectroscopy, and the results reveal that crosslinking occurs mainly via free-radical polymerization of the vinyl group. Furthermore, the results indicate that silicon carbonitride (SiCN) was formed after the pyrolysis. The results of the electrical properties of the amorphous ceramics differ in dependence on the amount of DVB in the formulation. A maximum electrical conductivity of 1.2 S/cm-1 was observed for a UV-cured sample with a high amount of DVB pyrolyzed at 1100 °C. The generation in electrical conductivity is given by the formation of free carbon derived most likely by DVB.