Iron nitride-based magnetic powder, process for producing the same, and magnetic recording medium

An iron nitride-based, powder-based technology, applied in magnetic recording, chemical instruments and methods, magnetic objects, etc., can solve the problems of poor weather resistance, etc., and achieve improved aging degradation, improved durability and reliability, and excellent The effect of weather resistance

Inactive Publication Date: 2009-06-24
DOWA ELECTRONICS MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] However, Fe 16 N 2 The iron nitride-based magnetic powder as the main phase is inherently not very good in terms of weather resistance, and the technology to overcome this has not yet been established.

Method used

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  • Iron nitride-based magnetic powder, process for producing the same, and magnetic recording medium
  • Iron nitride-based magnetic powder, process for producing the same, and magnetic recording medium
  • Iron nitride-based magnetic powder, process for producing the same, and magnetic recording medium

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0071] FeSO at 0.2mol / L (L means liter) 4 After adding 0.5 L of 12 mol / L NaOH aqueous solution and sodium aluminate in an amount of Al / Fe=20 atomic % to 4 L of the aqueous solution, while maintaining a liquid temperature of 40° C., air was blown in at a flow rate of 300 mL / min for 2.5 hours, thereby Precipitates the ferric hydroxide which solid-solutes Al. After this oxidation treatment, the precipitated ferric basic hydroxide was filtered, washed with water, and dispersed in water again. Yttrium nitrate in an amount of Y / Fe=1.0 atomic % was added to the dispersion, and a 12 mol / L NaOH aqueous solution was adjusted to pH=7 to 8 at 40° C. to coat the particle surface with yttrium. Thereafter, filtration and water washing were performed. Dry in air at 110°C.

[0072] As a result of compositional analysis of the obtained powder, the atomic ratios of Al and Y to Fe were Al / Fe=9.6 atomic % and Y / Fe=2.3 atomic %.

[0073] The obtained powder mainly composed of ferric basic hydro...

Embodiment 2

[0079] Except that in the "slow reduction treatment" of Example 1, the hydrogen concentration in the hydrogen-nitrogen mixed gas was changed to 1.0 vol%, and the treatment time was changed to 60 minutes, the magnetic powder was produced under the same conditions as in Example 1, And the same measurement as in Example 1 was performed.

Embodiment 3

[0081] Except that in the "slow reduction treatment" of Example 1, the hydrogen concentration in the hydrogen-nitrogen mixed gas was changed to 0.1 vol%, and the treatment time was changed to 180 minutes, the magnetic powder was produced under the same conditions as in Example 1, And the same measurement as in Example 1 was performed.

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Abstract

Provided is an iron nitride-based magnetic powder that comprises magnetic particles having a mean particle size of at most 20 nm. The magnetic particle has a core of a main phase of Fe 16 N 2 and has, on the outer side of the core, an oxide phase derived from a metal Fe phase formed by reduction of iron nitride. In relation to the weatherability index s and the saturation magnetization s thereof, the magnetic powder satisfies s 0.8 x s - 30. In this, s = (s - s 1 ) / s x 100. s 1 means the saturation magnetization of the magnetic powder kept in an atmosphere of 60 DEG C and 90 % RH for 1 week. The powder can be obtained by exposing powder particles having a main phase of Fe 16 N 2 to a reducing gas to partly reduce the region of the surface of the particles into a metal Fe phase (gradual reduction) followed by exposing them to an oxidizing gas to oxidize a part of the surface of the metal Fe phase into an oxide phase (gradual oxidation).

Description

technical field [0001] The present invention relates to an iron nitride-based magnetic powder used in a magnetic recording medium having a high recording density, and particularly relates to an iron nitride-based magnetic powder having improved weather resistance in which aging deterioration of magnetic properties is improved. Background technique [0002] As a magnetic powder with good magnetic properties suitable for high-density recording media, Fe 16 N 2 Iron nitride-based magnetic powder with phase as the main phase. For example, Patent Document 1 discloses an iron nitride-based magnetic material with a large specific surface area as a magnetic material exhibiting high coercive force (Hc) and high saturation magnetization (σs), and teaches that Fe 16 N 2 The superimposed effect of the crystal magnetic anisotropy of the phase and the increase in the specific surface area of ​​the magnetic powder makes it possible to obtain high magnetic properties regardless of its sh...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/09B22F1/00C01B21/06G11B5/712G11B5/714H01F1/06
CPCG11B5/70626C01P2004/80C01B21/0622H01F1/065C01P2004/64C01P2006/42G11B5/714H01F1/09B82Y30/00G11B5/712
Inventor 石川雄三正田宪司
Owner DOWA ELECTRONICS MATERIALS CO LTD
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