Ugimag Sa

Ugimac, S.a.

Eric Brando

Philippe Tenaud

Antoine Morel

A method for manufacturing type M hexaferrite powders fo the formula AFe O where A is Ba, Sr, Ca, Pb or a mixture thereof. An iron oxide Fe O and a compound A are mixed with a molar ratio n&equals;Fe O /AO, formed and calcined, and the agglomerates which result from the calcining are ground to obtain a fine ferrite powder. The mixture is formed with a ratio n ranging between 5.7 and 6.1, and with a predetermined degree of homogeneity, and before or during the grinding process, an agent controlling the microstructure is introduced.

Method for making m- type hexaferrite powders or wafers

A method for making ferrite magnets of formula M R Fe T O including: a1) forming a powder mixture MP of related raw materials, a2) transforming into granules in green state A, b) calcining the granules in green state to form clinker B, c) wet grinding clinker B to obtain a homogeneous dispersion of fine particles C, d) concentrating and compressing the particles under an orienting magnetic field to form an anisotropic green compact D, and e) sintering the green compact to obtain a sintered element E. In step a1), MP is formed from a dry mixture MS of M and Fe powder elements and a dispersion DF of raw materials related to elements R and T, and in step b) the granules in green state are calcined to obtain a clinker B which is homogeneous in chemical composition and size and with apparent low density, between 2.5 and 3.5.

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Laredo, TX, United States of America

Eric Brando