Unprecedented heat resistance of Fe-based soft magnetic composites realized with tunable double insulation layer: Synergy of MgO diffusion barrier and void-filling SiO2 layer

Preparation of Fe@Fe3O4/ZnFe2O4 Powders and Their Consolidation via Hybrid Cold-Sintering/Spark Plasma-Sintering

“…Soft magnetic composites (SMCs) constitute a significant subclass of the soft magnetic materials field due to their specific capability to produce innovative three-dimensional cores with high magnetic flux density and also due to their potential utilization in various electrical machinery fields [ 1 , 2 , 3 , 4 ]. In recent decades, researchers have focused on the enhancement of the magnetic properties of SMCs by studying the effects induced by the thin insulating layer on the surface and by optimizing their elaboration technology [ 4 , 5 , 6 , 7 , 8 ].…”

“…Soft magnetic composites (SMCs) constitute a significant subclass of the soft magnetic materials field due to their specific capability to produce innovative three-dimensional cores with high magnetic flux density and also due to their potential utilization in various electrical machinery fields [ 1 , 2 , 3 , 4 ]. In recent decades, researchers have focused on the enhancement of the magnetic properties of SMCs by studying the effects induced by the thin insulating layer on the surface and by optimizing their elaboration technology [ 4 , 5 , 6 , 7 , 8 ]. An organic insulating layer limits the thermal treatment temperature of SMCs, while an inorganic coating such as Al 2 O 3 , SiO 2 , or ZrO 2 degrades the saturation magnetization due to the magnetic dilution effect induced by the non-magnetic insulating layer [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

“…To overcome these deficiencies, ferromagnetic materials such as ferrite-type systems, Mn-Zn ferrites, Ni-Zn ferrites, and Fe x O y (especially Fe 3 O 4 ) have been considered as the suitable insulating layer [ 8 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Additionally, several studies present the elaboration of SMCs with an inorganic double-insulating layer that enhances heat resistance and enables enhanced magnetic and mechanical performance by high-temperature annealing [ 4 , 24 , 25 ].…”

“…Even if the dry methods are more facile, their efficiency is lower than the wet chemical approach because it is difficult to form a uniform coating layer on the surface of soft magnetic particles. Additionally, many efforts have been made to control layer thickness and reduce the defects or holes from the interface between the ferrite or oxide layer and metal, drastically diminishing the composite properties [ 1 , 2 , 3 , 4 , 5 , 6 ]. The melting point, resistivity, and bandgap energy are important characteristics of the coating layer.…”

“…The melting point, resistivity, and bandgap energy are important characteristics of the coating layer. A high-quality and uniform insulating layer effectively reduces eddy current losses by providing the material with remarkable insulation properties of resistivity and bandgap energy [ 4 ]. Recently, Zhang et al reported that the in situ oxidation method assures the formation of a uniform Fe 3 O 4 surface coating layer and, moreover, this method facilitates good control over the layer thickness [ 3 ].…”