The present application relates to an electromagnetic wave shielding film, which can provide an electromagnetic wave shielding film having excellent mechanical strength, flexibility, electrical insulation properties, bonding properties with other constituents, oxidation and high-temperature stability and the like, while having excellent electromagnetic shielding ability.

A compression molded core contains a plurality of soft magnetic material powders. A first powder and a second powder in the plurality of powders satisfy D1>D2, 0.23≤(D1−D2)/D1<0.6, D1≤7 μm, and 3 μm≤DT≤5.7 μm. D1 is the median diameter, which is a particle size at which the integrated particle diameter distribution from the small particle size side is 50% in a volume-based particle size distribution measured by a laser diffraction/scattering method, of the first powder and is maximum among median diameters; D2 is the median diameter D2 of the second powder and is minimum among median diameters; and DT is determined using the weight rate R1 of the first powder and the weight rate R2 of the second powder by R1×D1+R2×D2.

To obtain a magnetic core having an improved withstand voltage property while maintaining a high relative magnetic permeability, and the like. The magnetic core contains large particles observed as soft magnetic particles having a Heywood diameter of 5 μm or more and 25 μm or less and small particles observed as soft magnetic particles having a Heywood diameter of 0.5 μm or more and less than 5 μm in a cross section. C1<C2 is satisfied in which an average circularity of the small particles close to the large particles is C1 and an average circularity of all small particles observed in the cross section including small particles not close to the large particles is C2. The small particles close to the large particles are defined as small particles whose distance from centroids of the small particles to a surface of the large particles is 3 μm or less.

A synthesis process is disclosed for fabrication of mass quantities of high-purity α-MnBi magnetic powder and subsequent bulk permanent magnet. An illustrative process includes certain steps that include: multiple annealing, multiple comminuting such as multiple ball milling, forming a non-magnetic phase on and/or in the powder particles at particle grain boundaries before particle consolidation such as pressing, and magnetic annealing of a pressed compact. A reproducible and high productive synthesis process is created by combining these steps with other steps, which makes possible production of mass quantities of MnBi powder and bulk magnets with high performance.

A synthesis process is disclosed for fabrication of mass quantities of high-purity α-MnBi magnetic powder and subsequent bulk permanent magnet. An illustrative process includes certain steps that include: multiple annealing, multiple comminuting such as multiple ball milling, forming a non-magnetic phase on and/or in the powder particles at particle grain boundaries before particle consolidation such as pressing, and magnetic annealing of a pressed compact. A reproducible and high productive synthesis process is created by combining these steps with other steps, which makes possible production of mass quantities of MnBi powder and bulk magnets with high performance.

Provided is a new magnetic material with high magnetic stability, as well as a manufacturing method therefor, said magnetic material having a higher saturation magnetization than ferrite-based magnetic materials, and having a higher electrical resistivity than existing metal-based magnetic materials, thus solving problems such as that of eddy current loss. Mn-ferrite nanoparticles obtained through wet synthesis are reduced within hydrogen, and grains are allowed to grow while simultaneously using a phase separation phenomenon due to a disproportionation reaction to produce a magnetic material powder in which an α-(Fe, Mn) phase and a Mn-enriched phase are nano-dispersed. This powder is then sintered to produce a solid magnetic material.

Provided is a new magnetic material with high magnetic stability, as well as a manufacturing method therefor, said magnetic material having a higher saturation magnetization than ferrite-based magnetic materials, and having a higher electrical resistivity than existing metal-based magnetic materials, thus solving problems such as that of eddy current loss. Mn-ferrite nanoparticles obtained through wet synthesis are reduced within hydrogen, and grains are allowed to grow while simultaneously using a phase separation phenomenon due to a disproportionation reaction to produce a magnetic material powder in which an α-(Fe, Mn) phase and a Mn-enriched phase are nano-dispersed. This powder is then sintered to produce a solid magnetic material.

A soft magnetic material for soft magnetic particles with a high filling rate. The soft magnetic material contains first soft magnetic particles and second soft magnetic particles with a larger average particle size than the first soft magnetic particles. The first soft magnetic particles have an average particle size in the range of 0.5 to 10 μm, and the first soft magnetic particles have a nonpolar hydrocarbon group on their surfaces.

A soft magnetic material for soft magnetic particles with a high filling rate. The soft magnetic material contains first soft magnetic particles and second soft magnetic particles with a larger average particle size than the first soft magnetic particles. The first soft magnetic particles have an average particle size in the range of 0.5 to 10 μm, and the first soft magnetic particles have a nonpolar hydrocarbon group on their surfaces.

A method for manufacturing a powder magnetic core using a soft magnetic material powder, wherein the method has: a first step of mixing the soft magnetic material powder with a binder, a second step of subjecting a mixture obtained through the first step to pressure forming, and a third step of subjecting a formed body obtained through the second step to heat treatment. The soft magnetic material powder is an Fe—Cr—Al based alloy powder comprising Fe, Cr and Al. An oxide layer is formed on a surface of the soft magnetic material powder by the heat treatment. The oxide layer has a higher ratio by mass of Al to the sum of Fe, Cr and Al than an alloy phase inside the powder.