Method for preparing barium-ferrite-coated .gamma.FE.sub.2 O.sub.3 magnetic power
AssigneeNational Science Council
InventorsTsung-Shune Chin, Sung-Lin Hsu, Ming-Cheng Deng
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Abstract
A method for preparing a barium-ferrite-coated, needle-shaped .gamma.-Fe.sub.2 O.sub.3 magnetic powder of better properties is provided. The method includes the following steps of a) letting an iron-containing solution undergo a reaction to precipitate a needle-shaped .alpha.-FeOOH phase powder, b) mixing said .alpha.-FeOOH powder into a barium-containing solution in a predetermined Fe/Ba ratio, c) filtering without washing the precipitated powder, and d) subjecting the precipitated powder to heat treatments including calcination, reduction and oxidation.
Claims24
A method for preparing a barium-ferrite-coated .gamma.-Fe.sub.2 O.sub.3 magnetic powder comprising the following steps:
- (a) letting an iron-containing solution undergo a reaction to precipitate a needle-shaped .alpha.-FeOOH phase powder;
- (b) mixing said .alpha.-FeOOH powder with a barium-containing solution to obtain a barium-bearing .alpha.-FeOOH powder;
- (c) filtering and stoving said barium-bearing .alpha.-FeOOH powder;
- (d) subjecting said stoved barium-bearing .alpha.-FeOOH powder to a first heat treatment of calcination to obtain a powder containing a barium-ferrite phase and a .alpha.-Fe.sub.2 O.sub.3 phase;
- (e) subjecting the resultant powder of step (d) to a second heat treatment to reduce said .alpha.-Fe.sub.2 O.sub.3 phase of said powder to a Fe.sub.3 O.sub.4 phase;
- and
- (f) subjecting the resultant powder in step (e) to a third heat treatment to oxidize said Fe.sub.3 O.sub.4 phase of said powder to a .gamma.-Fe.sub.2 O.sub.3 phase.
Dependencies are inferred from the claim text.