Process for producing single phase magnetite powder
AssigneeFuji Electrochemical Co., Ltd.
InventorsYasuhiko Mano, Takeshi Mochizuki, Isamu Sasaki, Akira Shimokawa
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Abstract
Hematite powder is mixed with a substance having a carbon-to-carbon single or double bond, and sintered in an inert gas to form magnetite powder. The magnetite powder can be provided with a desired electric resistance while retaining the properties characteristic of the magnetite powder by effecting a heating in an oxygenic atmosphere after the formation of the magnetite powder (or during a cooling subsequent to the sintering in the inert gas).
Claims5
A process for producing single phase magnetite powder, comprising adding 0.1 to 4.0% by weight of a liquid or powdered substance having a carbon-to-carbon single or double bond to hematite powder, stirring the mixture to obtain a substantially homogeneous mixture, and heating the mixture in an inert gas at 1200.degree. to 450.degree. C.
A process for producing single phase magnetite powder, comprising adding 0.1 to 4.0% by weight of a liquid or powdered substance having a carbon-to-carbon single or double bond to hematite powder, stirring the mixture to obtain a substantially homogeneous mixture, and heating the mixture in an inert gas at 1200.degree. to 1450.degree. C. wherein, after said heating, cooling is performed at a temperature regulated to 300.degree. C. or below, wherein during said cooling step an atmosphere having an oxygen concentration regulated to 0.1 to 21% by weight is provided to thereby cause the magnetite powder to have a desired electric resistance.
A process for producing single phase magnetite powder, comprising adding 0.1 to 4.0% by weight of a liquid or powdered substance having a carbon-to-carbon single or double bond to hematite powder, stirring the mixture to obtain a substantially homogeneous mixture, and heating the mixture in an inert gas at 1200.degree. to 1450.degree. C. wherein, after said heating in the inert gas, the resultant magnetite powder is subjected to a second heating in an atmosphere having an oxygen concentration of 0.1 to 21% by weight at 250.degree. to 300.degree. C.
Dependencies are inferred from the claim text.