Design of Insulation Layer Structures in 3-Dimensional Fe-6.5%Si Cores via Dual-nozzle Material Extrusion combined with Spark Plasma Sintering technology

We present a novel hybrid manufacturing approach that combines dual-nozzle material extrusion and spark plasma sintering to fabricate metal–insulator–metal-structured Fe-6.5 wt.% Si (Fe-6.5Si) magnetic cores. This process integrates MgO-B2O3-SiO2 (MBS) insulation layers to achieve enhanced bonding between the layers. The manufacturing process involved integrating MBS insulation for structural integrity, reducing the Fe-6.5Si layer thickness for frequency stability, and applying a post-heat treatment to improve magnetic performance. The MBS insulation system demonstrated sinterability, forming stable interfaces with the Fe-6.5Si layers. Through experimental investigation, we found that a Fe-6.5Si layer thickness of 0.6 mm combined with 0.2-mm MBS insulation layers exhibited promising frequency stability up to 1 kHz. Additionally, post-heat treatment at 1200 °C enhances the magnetic properties by increasing the permeability and reducing hysteresis loss through grain growth and interface modification. This manufacturing approach has the potential to produce high-performance magnetic cores while offering design possibilities for fabricating various part geometries compared with conventional methods.本研究提出一种新型复合制备工艺，将双喷嘴材料挤出成型（dual-nozzle material extrusion）与放电等离子烧结（spark plasma sintering）相结合，用于制备金属-绝缘体-金属（metal-insulator-metal, MIM）结构的Fe-6.5 wt.%硅（Fe-6.5Si）磁芯。该工艺引入氧化镁-氧化硼-二氧化硅（MgO-B2O3-SiO2，MBS）绝缘层，以提升各层之间的结合强度。本次制备流程通过引入MBS绝缘层保障结构完整性、减小Fe-6.5Si层厚度以提升频率稳定性，以及采用后置热处理工艺优化磁性能。MBS绝缘体系展现出良好的烧结适应性，可与Fe-6.5Si层形成稳定的界面结合。经实验研究发现，当Fe-6.5Si层厚度为0.6 mm、搭配0.2 mm厚的MBS绝缘层时，样品在最高1 kHz的频段内展现出优异的频率稳定性。此外，在1200 ℃下进行的后置热处理可通过晶粒长大与界面调控，提升磁导率并降低磁滞损耗，从而优化磁性能。相较于传统制备工艺，本复合制备工艺不仅可制备高性能磁芯，还能为多样化零件几何结构的成型提供设计灵活性。