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AssigneeNippon Steel Corporation
InventorsKatsushige Matsuzaki, Tatsunori Sunagawa, Kenji Kawahito, Junji Omori, Yoshitaka Yamana, Shoichi Osada, Kiyoshi Aritome, Yoshimasa Ikeda, Izumi Matsushita, Wataru Ohashi, Kaoru Ito, Fumihiko Hasegawa, Shinya Nariki, Michimasa Sasaki, Noritane Tsugane, Toshiaki Kurihara
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This invention provides an atomization roasting method which can easily obtain a soft ferrite sintered body, for example, a sintered body having a crystal particle size of not greater than 2 .mu.m, by using as a raw material an ultra-fine powder having a mean particle size of not greater than 0.1 .mu.m obtained by atomization roasting and which can obtain a soft ferrite raw material powder subjected to an oxidation reaction, having an extremely small residual chlorine content, and having and extremely small deviation of high vapor pressure components such as zinc between the atomized raw material solution and the oxide as the product and which can economically produce a soft ferrite core having an excellent power loss characteristic in a high frequency range, particularly in a MHz range, and is extremely effective for reducing the size of a high frequency transformer. In the production method of the soft ferrite raw material powder, the deviation of the recovered powder becomes extremely small and residual hydrogen chloride and chlorides can be reduced. Therefore, loads to the component adjustment step after roasting and to the Cl removing step can be reduced and process steps can be eliminated. Accordingly, the present invention can drastically reduce the cost of production and can improve quality.
An Mn--Zn soft ferrite raw material powder produced by a high temperature oxidation method comprising 65-85 wt. % Fe, calculated as Fe.sub.2 O.sub.3, 10-30 wt. % Mn, calculated as MnO, and 2-25 wt. % Zn, calculated as ZnO and a P and a Cr content of P.ltoreq.20 ppm and Cr.ltoreq.50 ppm and having a mean particle diameter of not greater than 0.1 .mu.m and composition deviation of Fe.sub.2 O.sub.3, MnO and ZnO is microscopically homogenous.
A soft ferrite sintered body produced by normal pressure sintering of a Mn--Zn soft ferrite raw material powder produced by a high temperature oxidation method, said Mn--Zn soft ferrite raw material powder comprising 65-85 wt. % Fe, calculated as Fe.sub.2 O.sub.3, 10-30 wt. % Mn, calculated as MnO, and 2-25 wt. % Zn, calculated as ZnO, and a P and a Cr content of P.ltoreq.20 ppm and Cr.ltoreq.50 ppm and having a mean particle diameter of not greater than 0.1 .mu.m and composition deviation of Fe.sub.2 O.sub.3, MnO and ZnO is microscopically homogenous.
A soft ferrite sintered body produced by direct granulation molding and subsequent normal pressure sintering at a temperature below 1,100.degree. C. of an Mn--Zn soft ferrite raw material powder produced by a high temperature oxidation method,
A method for producing a soft ferrite sintered body in a sintering process, said soft ferrite sintered body having a mean crystal particle diameter of not greater than 2 .mu.m, comprising the steps of:
A method for producing a soft ferrite raw material powder comprising the steps of:
A method for producing a soft ferrite raw material powder comprising:
Dependencies are inferred from the claim text.