US 10,919,809 B2 · MnZn ferrite and its production method

Abstract

A method for producing MnZn ferrite comprising Fe, Mn and Zn as main components, and Ca, Si and Co, and at least one selected from the group consisting of Ta, Nb and Zr as sub-components, comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body, and a step of sintering the green body; the sintering step comprising a temperature-elevating step, a high-temperature-keeping step, and a cooling step; the cooling step including a slow cooling step of cooling in a temperature range of 1100° C. to 1250° C. at a cooling speed of 0° C./hour to 20° C./hour for 1 hours to 20 hours, and a cooling speed before and after the slow cooling step being higher than 20° C./hour; the MnZn ferrite having a volume resistivity of 8.5 Ω·m or more at room temperature, an average crystal grain size of 7 μm to 15 μm, and core loss of 420 kW/m3 or less between 23° C. and 140° C. at a frequency of 100 kHz and an exciting magnetic flux density of 200 mT.

Claims6

Dependent claims

A method for producing MnZn ferrite comprising Fe, Mn and Zn as main components, and Ca, Si and Co, and at least one selected from the group consisting of Ta, Nb and Zr as sub-components, comprising

a step of molding a raw material powder for said MnZn ferrite to obtain a green body, and
a step of sintering said green body;
said sintering step comprising a temperature-elevating step, a high-temperature-keeping step, and a cooling step;
said cooling step including a slow cooling step of cooling in a temperature range of 1100° C. to 1250° C. at a cooling speed of 0° C./hour to 20° C./hour for 1 hours to 20 hours, and
a cooling speed before and after said slow cooling step being higher than 20° C./hour;
said MnZn ferrite having a volume resistivity of 8.5 Ω·m or more at room temperature, an average crystal grain size of 7 μm to 15 μm and core loss of 420 kW/m3 or less between 23° C. and 140° C. at a frequency of 100 kHz and an exciting magnetic flux density of 200 mT.

3 more elements

MnZn ferrite comprising 53-54% by mol of Fe (calculated as Fe2O3), and 8.2-10.2% by mol of Zn (calculated as ZnO), the balance being Mn (calculated as MnO), as main components, and

more than 0.001 parts by mass and 0.015 parts by mass or less of Si (calculated as SiO2), more than 0.1 parts by mass and 0.35 parts by mass or less of Ca (calculated as CaCO3), 0.4 parts by mass or less (not including 0) of Co (calculated as Co3O4), 0.1 parts by mass or less (including 0) of Ta (calculated as Ta2O5), 0.1 parts by mass or less (including 0) of Zr (calculated as ZrO2), and 0.05 parts by mass or less (including 0) of Nb (calculated as Nb2O5), the total amount of Ta2O5, ZrO2 and Nb2O5 being 0.1 parts by mass or less (not including 0), as sub-components, per 100 parts by mass in total of said main components (calculated as said oxides),
said MnZn ferrite having a volume resistivity of 8.5 Ω·m or more at room temperature, an average crystal grain size of 7 μm to 15 μm, core loss of 420 kW/m3 or less between 23° C. and 140° C. at a frequency of 100 kHz and an exciting magnetic flux density of 200 mT, and initial permeability μi of 2800 or more at a frequency of 100 kHz and at 20° C.

Dependencies are inferred from the claim text.

MnZn ferrite and its production method

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MnZn ferrite and its production method

Life of this patent

Abstract

Claims6