Soft magnetic materials

Powder metallurgical manufacturing concepts offer a wide range of possibilities to produce soft magnetic components that go far beyond traditional manufacturing technologies. Thus, soft magnetic components with a special property profile can be manufactured in alternative geometries. Focus of the work is the reduction of iron losses while increasing magnetic performance using near net shape manufacturing strategies.

Different powder metallurgical manufacturing concepts are pursued to address the application-specific characteristics. All methods have in common that the choice of materials is broader and the integration of additional functions is possible.

• Powder composites: The production of isotropic powder composites with high permeabilities (µ_max > 200) is carried out by conventional pressing of coated soft magnetic powder for their electrical insulation. The powders are coated using the sol-gel method. Heat treatment is necessary to achieve optimum properties. Various furnaces are available to realize the respective temperature profile in the desired atmosphere.

• Magnetic characterization: The characterization is carried out by measuring B-H curves on ribbons or toroidal cores in AC or DC field. In particular, the magnetic performance and the frequency-dependent losses are determined either using B-H-analyzer (f < 20 kHz) or LCR meter (f > 20 kHz).
• Mechanical characterization: The mechanical strength is evaluated by means of tensile/compression test or hardness measurement.
• Structural characterization: Sections of the components are examined under a light or scanning electron microscope to correlate functional properties with microstructure. The effect of powder properties in particular is investigated. Therefore, a comprehensive powder characterization is carried out in our accredited laboratory beforehand. This includes particle size distribution, morphology and impurity content.

Dr. Inge Lindemann's “Soft Magnetic Materials” working group researches the powder metallurgical production of application-relevant material concepts for the manufacture of loss-optimized soft magnetic components. In the “Powder Metallurgy” department, the group has comprehensive expertise and the latest powder processing technologies, which also take generative manufacturing into account. The fields of application range from modern energy converters in electrical machines and power electronics.

The project „WeiMag – Gezielte Eigenschaftsverbesserung durch innovative Pulvertechnologien“ is funded internally by the Fraunhofer Attract program.

The project "WeiMag" (600420) is funded internally through the Fraunhofer Attract program.