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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fe-based Amorphous Powder for Soft-Magnetic Composites

Larsson, Oskar January 2013 (has links)
Fe-based amorphous powders are fabricated through gas and water atomization using industrial grade raw materials. The atomic structure of the powder is examined by X-Ray Diffraction (XRD). Eight of totally thirteen different compositions are proved completely amorphous or amorphous with traces of crystalline phase in the desired powder particle size (d > 75 μm) and five are crystalline. It reveals that the Glass Forming Ability (GFA) of atomized powders is well correlated to the GFA of as-casted rods or melt-span ribbons. In the present study at least 1.5-2 mm critical size of GFA for a target composition is necessary for the formation of amorphous powders in the desired particle size. The thermal stability of the amorphous powder is examined by Differential Scanning Calorimetry (DSC). Applying the conventional powder metallurgy process the amorphous powders are mixed with the crystalline Somaloy® 110i, a commercial Soft Magnetic Composite (SMC) material from Höganäs AB in Sweden, and made into toroid-shaped components. The components are annealed aiming for improved soft-magnetic properties. The magnetic measurements are taken on copper-wire double coiled toroids. As a result, the total magnetic flux (B), coercivity (HC) and permeability (μmax) is reduced due to the addition of amorphous powders to Somaloy® 110i powder but the core losses (P) is at the same level despite reduced density. An improved soft magnetic property and core loss is revealed by the comparison to recent literature reports on SMC mixing of crystalline and amorphous powders.

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