Minebea Company, Limited

Koji Honda

Osamu Kobayashi

Shunji Kawasaki

Osamu Yamada

A process for producing Mn&mdash;Zn ferrite having large electrical resistance and being durable to the use in high frequency region exceeding 1 MHz easily and at low cost is disclosed. The process comprises pressing a mixed powder comprising a composition of 44.0 to 50.0 mol % of Fe O , 4.0 to 26.5 mol % of ZnO, 0.1 to 8.0 mol % of at least one member selected from the group consisting of TiO and SnO , and the remainder being MnO, and if desired 0.1 to 16.0 mol % of CuO, sintering the resulting green compact in the air or an atmosphere containing an appropriate amount of oxygen, and then cooling the green compact, thereby securing the estimated high initial permeability even in a high frequency region of 1 MHz or more.

Process for producing Mn-Zn ferrite

A process for producing Mn&mdash;Zn ferrite is disclosed, which enables regeneration and reuse of scraps of a sintered product. The process comprises reusing a powder obtained by milling the sintered product of Mn&mdash;Zn ferrite, subjecting the powder to a component adjustment so as to have a composition of 44.0 to 50.0 mol % of Fe,O,, 4.0 to 26.5 mol % of ZnO, 0.1 to 8.0 mol % of at least one member selected from the group consisting of TiO,and SnO,, and the remainder being MnO, and optionally 0.1 to 16.0 mol % of CuO, pressing the resulting mixed powder after the component adjustment, and then sintered a green compact.

Mn-Zn ferrite

A Mn&mdash;Zn ferrite having large electrical resistance, which can withstand the use in high frequency region exceeding 1 MHz, is provided. The Mn&mdash;Zn ferrite comprises the following basic components: 44.0 to 50.0 mol % Fe,O,, 4.0 to 26.5 mol % ZnO, 0.1 to 8.0 mol % at least one member selected from the group consisting of TiO,and SnO,, 0.1 to 16.0 mol % CuO, and the remainder being MnO. By the addition of TiO,, SnO,and CuO, even if the material is sintered in the air, electrical resistance of 10,times or more as high as that of the conventional Mn&mdash;Zn ferrite can be obtained, and a high initial permeability of 300-400 as estimated can be secured even at high frequency of 5 MHz.

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Asaba-cho, Japan

Koji Honda