Jfe Chemical Corporation

Jfe Steel Corporation

Yukiko Nakamura

Satoshi Goto

Hirofumi Yoshida

Satoshi Uenosono

Hiroki Nakamaru

Shigeru Unami

Yukiko Ozaki

Naoki Soga

Shingo Saito

Shigeaki Takajo

Azumi Nojima

Disclosed is a MnZnCo-based ferrite consisting of base constituents, accessory constituents, and inevitable impurities, which MnZnCo-based ferrite is characterized by adding silicon oxide (SiO2 conversion): 50-400 mass ppm and calcium oxide (CaO conversion): 1000-4000 mass ppm as secondary constituents to base constituents consisting of iron oxide (Fe2O3 conversion): 51.0-53.0 mol %, zinc oxide (ZnO conversion): greater than 12.0 mol % and less than 18.0 mol %, cobalt oxide (CoO conversion): 0.04-0.60 mol %, and manganese oxide (MnO conversion): remainder, and keeping phosphorus, boron, sulfur, and chlorine of the inevitable impurities to phosphorous: less than 3 mass ppm, boron: less than 3 mass ppm, sulfur: less than 5 mass ppm, and chlorine: less than 10 mass ppm. This MnZnCo-based ferrite has the superior characteristics of always having incremental permeability [mu]? of 2000 or greater across a wide temperature range of &#x2212;40 DEG C. to 85 DEG C. when a 33 A/m direct current magnetic field is applied, even in cases when formed into a small core with outside diameter of approximately 2-6 mm.

Mn-Zn-co ferrite

A Mn&#x2014;Zn&#x2014;Co ferrite core includes a basic component, sub-components, and unavoidable impurities. As the sub-components, silicon oxide (in terms of SiO): 50-400 mass ppm and calcium oxide (in terms of CaO): 1000-4000 mass ppm are added to the basic component consisting of iron oxide (in terms of FeO): 51.0-53.0 mol %, zinc oxide (in terms of ZnO): more than 12.0 mol % and 18.0 mol % or less, cobalt oxide (in terms of CoO): 0.04-0.60 mol %, and manganese oxide (in terms of MnO): balance; Phosphorus, boron, sulfur, and chlorine in the unavoidable impurities are reduced as follows, phosphorus: less than 3 mass ppm, boron: less than 3 mass ppm, sulfur: less than 5 mass ppm, and chlorine: less than 10 mass ppm; and a ratio of a measured specific surface of the Mn&#x2014;Zn&#x2014;Co ferrite core to an ideal specific surface of the Mn&#x2014;Zn&#x2014;Co ferrite core satisfies: Measured specific surface/ideal specific surface &#x3c;1500.

Mn-Zn-Co ferrite core and method for producing the same

Disclosed is a MnZn ferrite core comprising basic components, subcomponents and unavoidable impurities. To the basic components comprising: iron oxide (as FeO): 51.0-54.5 mol %, zinc oxide (as ZnO): 8.0-12.0 mol % and manganese oxide (as MnO): remainder, are added silicon oxide (as SiO): 50-400 mass ppm and calcium oxide (as CaO): 50-4000 ppm as subcomponents and in the unavoidable impurities, phosphorous, boron, sulfur and chlorine are respectively kept to: less than 3 mass ppm, less than 3 mass ppm, less than 5 mass ppm, and less than 10 mass ppm. The ratio of the measure specific surface area to the ideal specific surface area of the MnZn ferrite core satisfies the formula: Measured specific surface area/ideal specific surface area&#x3c;1500.

Mn&#x2014;Zn ferrite core and method for producing the same

A MnZn ferrite having excellent characteristics of an incremental permeability &#x3bc;&#x394; value of 250 or greater in a wide temperature range of 0 to 85&#xb0; C. and an incremental permeability &#x3bc;&#x394; value of 400 or greater at 65&#xb0; C. when an 80 A/m direct current magnetic field is applied is provided. The MnZn ferrite has basic components that comprise: ferric oxide (in terms of FeO): 51.0 to 54.5 mol %, zinc oxide (in terms of ZnO): 8.0 to 12.0 mol %, and manganese oxide (in terms of MnO): the balance, sub components that comprise: silicon oxide (in terms of SiO2): 50 to 400 mass ppm, and calcium oxide (in terms of CaO): 50 to 400 mass ppm, and unavoidable impurities phosphorous, boron, sulfur and chlorine that are restricted to phosphorous: less than 3 mass ppm, boron: less than 3 mass ppm, sulfur: less than 5 mass ppm, and chlorine: less than 10 mass ppm.

MnZn ferrite and a transformer magnetic core

A magnetite-iron based composite powder includes magnetite with a ratio of X-ray diffraction intensity to that of &agr;-Fe of about 0.001 to about 50 and has an average primary particle size of about 0.1 to about 10 &mgr;m. The composite powder can highly dehalogenate organic halogen compounds and exhibits satisfactory absorption power of high frequency electromagnetic waves after molding. An ultrafine nonferrous inorganic compound powder may adhere to the surface of the composite powder, or at least the composite powder may adhere to the surfaces of small particles of a nonferrous inorganic compound to thereby yield a composite powder composition. The composite powder can be produced by partial reduction of a material powder containing a hematite based powder or by complete reduction and subsequent partial oxidation of the material powder.

Magnetite-iron based composite powder, magnetite-iron based powder mixture, method for producing the same, method for remedying polluted soil, water or gases and electromagnetic wave absorber

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Chiba, Japan

Yukiko Nakamura