Magnetic iron based powder having high coercive force, and their use for a magnetic recording medium

A technology of coercive force and magnetism, which is applied in magnetic recording, magnetic materials of recording carriers, magnetic objects, etc., can solve the problems of magnetic performance degradation, oxidation resistance degradation, etc., and achieve performance improvement, improvement of refinement increase, and recording density Improved effect

Inactive Publication Date: 2007-06-06
DOWA ELECTRONICS MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] However, when grain refinement reaches a point where the reduction in grain volume exceeds a certain level, thermal fluctuations lead to a significant deterioration of magnetic properties, and further reduction in grain size induces superparamagnetism, at which point magnetic properties cease to exhibit
Another problem is that the oxidation resistance deteriorates with the increase of the specific surface area with the refinement of the particle size

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0047] (1) Preparation of magnetic coating materials

[0048]Weigh out 0.500 g of magnetic powder and put it into a jar (inner diameter: 45 mm, depth: 13 mm), and keep it for 10 minutes with the lid open. Then, use a micropipette to transfer 0.700ml of medium [MR-110 vinyl chloride resin (22 mass percent), cyclohexanone (38.7 mass percent), acetylacetone (0.3 mass percent), n-butyl stearate (0.3 Mass percentage) and methyl ethyl ketone (MEK) (38.7 mass percentage) mixed solution] was added to the tank. Then immediately add 30 g of steel balls (2 mm) and ten nylon balls (8 mm) to the tank to cover the tank and keep it for 10 minutes. The jar was then placed in a centrifugal ball mill (Fritsch P-6), and the speed of the ball mill was gradually increased to 600 rpm, and the dispersion was continued at this speed for 60 minutes. Then the ball mill was stopped, the jar was taken out, and 1.800 ml of the adjustment solution prepared in advance by mixing MEK and toluene in a ratio of 1:1...

Embodiment 1

[0055] To 4 liters of FeSO 4 Add 0.5 liters of NaOH 12mol / l aqueous solution and a certain amount of sodium tungstate dihydrate to the 0.2mol / l aqueous solution, so that W / Fe (here and below, the atomic ratio of W to Fe) = 1.0 atomic%, and A certain amount of sodium aluminate, thus Al / Fe=20 atomic %. Then, the mixture was maintained at a temperature of 40° C. for a period of 2.5 hours while blowing air at a flow rate of 300 ml / min, whereby iron oxyhydroxide containing W and Al in the solid solution was precipitated. When the oxidation treatment is completed, the precipitated iron oxyhydroxide is filtered, washed, and dispersed in water again. Add a certain amount of yttrium nitrate to the dispersion to make Y / Fe=1.0 atomic%, and adjust the pH to 7-8 at a temperature of 40°C using a 12mol / l aqueous solution of NaOH, thereby attaching yttrium to the particles On the surface, these particles are then filtered, washed and dried in air at a temperature of 110°C.

[0056] The compositio...

Embodiment 2

[0060] Except that a certain amount of sodium tungstate dihydrate was added in the iron oxyhydroxide precipitation step so that W / Fe=0.1 atomic %, the magnetic powder was prepared under the same conditions as in Example 1. The same measurement as in Example 1 was performed.

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Abstract

A magnetic powder is provided composed of particles that, even when the particle size is refined, exhibits excellent magnetic properties, in particular, a high coercive force, for use in a high-density recording medium. The invention also provides a magnetic recording medium using the powder. The powder is an iron system magnetic powder containing, as an atomic ratio of Fe, a total of 0.01 to 10 atom% of one or more selected from W and Mo, particularly a magnetic powder comprised mainly of Fe16N2. The magnetic powder is able to exhibit a high coercive force of 238 kA / m (3000 Oe) or more. In addition to the W and Mo, the magnetic powder may contain, as an atomic ratio of Fe, a total of up to 25 atom% of one or more selected from Al and a rare earth element (defined as including Y).

Description

Technical field [0001] The present invention relates to an iron-based magnetic powder used for a high recording density magnetic recording medium, and particularly relates to a powder having a high coercivity Hc, and relates to a magnetic recording medium using the iron-based magnetic powder. Background technique [0002] In order to achieve higher and higher recording densities required by current magnetic recording media, the recording wavelength is being shortened. However, this requires that the size of the magnetic particles is much smaller than the length of the area for recording short-wavelength signals. If this is not the case, no significant magnetic transition can be produced, making actual recording impossible. The particle size of the magnetic powder must therefore be sufficiently smaller than the recording wavelength. [0003] To achieve higher recording density, it is also necessary to improve the resolution of the recorded signal, so reducing the noise of the magn...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/06G11B5/706G11B5/714B22F1/054
CPCB22F2998/00C01B21/0622C01P2002/74B22F1/0018C22C33/0257C01B21/0602G11B5/70615B22F2998/10C01P2002/72H01F1/065C01P2004/64C01P2006/42H01F1/09G11B5/70626B82Y30/00B22F1/054B22F9/22B22F2201/013B22F2201/016B22F9/24B22F2201/02
Inventor 石川雄三正田宪司
Owner DOWA ELECTRONICS MATERIALS CO LTD
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