JPS5931801A - Magnetic powder and its production - Google Patents

Abstract

PURPOSE:To produce easily uniform and stable magnetic powder having high coercive force by precipitating ferromagnetic material in the pores of the film of nonmagnetic porous aluminum oxide by an electroplating method then grinding the film to fine particles. CONSTITUTION:A base material 1 of aluminum or an aluminum alloy is anodized to form the film 2 of porous aluminum oxide 2a. A ferromagnetic material 3 of a ferromagnetic metal or ferromagnetic alloy is precipitated by an electroplating method in the many pores 2b which are parallel to the surface of the film 2 and are parallel with each other. The film 2 is separated by dissolving the base body 1 and is ground, whereby fine particles 4 that provide magnetic powder are obtained. Since the fine particles 4 hold the acicular ferromagnetic material 3 in the pores 2b of the nonmagnetic aluminum oxide 2a, the particles have a high coercive force characteristics and is free from the deterioration in the coercive force owing to the mutual magnetic effect among the particles and the sintering of the powder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic powder having a high coercive force and particularly promising as a magnetic recording material, and its J'! ! It is related to the method of sending.

Conventionally, magnetic recording media such as magnetic cards and magnetic recording media are made of iron oxide (r -Fe*) with a coercivity of about 200 to 4000e
Magnetic powder consisting of Og) has been commonly used, but
As devices become more sophisticated and smaller, magnetic powders with coercive force that enable even higher density recording are required.As a result, cobalt-modified iron oxide (Co -Fe*Os) has become widely used.

However, the coercive force of these iron oxide powders is not sufficient to meet the demands for even higher density recording and improved frequency characteristics, and these days, the coercive force of 1000-15000e
Fa-G has a high coercive force.

Alloy magnetic powders such as alloys are being developed and put into practical use. Typical manufacturing methods for this type of alloy magnetic powder are shown in the following (a) to (e).

C) Method of reducing metal by adding sodium borohydride gold to water-soluble needles.

0)) A method of vaporizing ferromagnetic metals in an inert gas.

(c) A method of heating, decomposing, and reducing ferromagnetic gold A-4 containing ferromagnetic gold at 14°C in one magnetic material.

(C1) Ferromagnetic metal by electroplating method: A method in which ferromagnetic metal is deposited in mercury by lightning and then heated to 11 degrees to separate it from mercury.

(e) A method of reducing oxide powder with hydrogen.

However, each of the methods listed here has its own drawbacks.
), the above method (q) produces powder with a uniform composition, ν′ size, and shape. ,) is ρill<,t.In the method (1) above, 1. In addition, method (C) has problems such as poor productivity and high price, and the large particle size of the powder obtained in method (C) results in high miscellaneous materials when used as a magnetic recording medium. However, the above Rt3 (') method has drawbacks such as difficulty in separating it from mercury and not mentioned in the industrial field.

However, in the above method (c), relatively uniform acicular powder is obtained as 111. Although it is most suitable for practical use because it can be obtained commercially, it can be obtained by wet method and hydrogen addition in a stream of hydrogen.
':'J1. with tcL original process. η1 at the top of IA
It has drawbacks such as deterioration of magnetic QC/N and ° properties due to reduction-like collapse, non-uniformity, and L-shape. Soil/ζ
, top): I: Mawariba l: Law. Koyoru base metal magnetism 5) end tJ
, The rock surface is active.1. Daru Tani'), popular VCJIM
An oxidation reaction occurs as soon as the powder is heated, resulting in deterioration of toughness.Therefore, there is also the drawback that a stabilizing treatment is required on the powder surface.

Therefore, the present invention (in view of the above-mentioned drawbacks) is a J-shifted product which has a high retention force and can produce h1 uniformly.
! Easy to prepare and stable magnetic powder and its manufacturing method
The purpose is to serve M.

In order to achieve all of these objectives, ``Unexploded 1M'' Q, 15,
(1) Ferromagnetic gold ri) or ferromagnetic gold 41. Porous aluminium oxide fully filled with self-metallic material J.
・Features Y construction, and (2) aluminum or tJ, aluminum alloy,
(The s-body is anodized to form a porous aluminum oxide film on the entire ring, and a ferromagnetic metal or ferromagnetic alloy is deposited in this porous aluminum aluminum oxide film by electroplating. The porous aluminum oxide film, in which the pores are filled with metal or ferromagnetic α-gold, is separated from the aluminum or aluminum alloy substrate or crushed into one particle. It is characterized by

+? which is magnetic powder in such plum pickles and methods? II
I) As a +j: It is necessary to make it by crushing the ferromagnetic metal or ferromagnetic alloy filled in the pores of a heavy aluminum alloy without destroying it.

The diameter of the acicular ferromagnetic metal or ferromagnetic alloy can be reduced by changing the size of the fine particles and the diameter of the holes. Depending on the crushing conditions such as, sjlti is usually less than 1llrrL. On the other hand, la3. The fine ferromagnetic metal particles or ferromagnetic alloy particles in the pores of aluminum oxide depending on polar oxidation treatment and 1(i5 plating method) have a diameter of 0.01 to 0.00.
About 0.02-g, with dimensions l p nt , length 0.1-l // rn (this length t, l: depends on the grain size), are added at intervals of 1 p m in aluminum oxide. Aligned in the direction. Therefore, Iin sr, even if finely ground as a child, the aluminum oxide particles are aligned in the holes of the
``B) The state of gold percent 1 child will not be destroyed.

As a result, magnetic powder, fine particles 3.1: ferromagnetic metal particles or ferromagnetic alloy J'iχ particles, which are magnetic powders, have a single magnetic domain with large shape anisotropy, which is known to exhibit a high coercive force. It has a high coercive force due to its small rise. In addition, fine-grained individual ferromagnetic metal particles or bone-shaped ferromagnetic alloy particles are held in non-magnetic aluminum oxide (1). 1. Improved magnetic interaction between powders and sintering of powders, which were disadvantages of powders.
,ru(li: There is no decrease in magnetic force.Also, aluminum oxide film, -: The shape of the ferromagnetic alloy particles is stable.Furthermore, the magnetic powder i, 110 (/:r-) indicates that the ferromagnetic metal particles or ferromagnetic alloy particles are chemically stable aluminum oxide. Because it is a covered JII structure, it is very stable even in the atmosphere, and there is no need for surface stabilization treatment performed with conventional alloy magnetic powders.

Here, an overview of an example of the manufacturing method ξ will be described with reference to Figures 8rl, J, O, L and 2. Figure 1 shows a process flowchart of the method for producing magnetic powder, and shows a schematic diagram of the second (n1 is a name) two culms. , an aluminum or aluminum base metal substrate 1 in the form of a plate or a horizontal foil is prepared.This substrate 1 is anodized in a post-process to form a porous aluminum oxide film having a pore structure straight and parallel to each other on the surface of the substrate. It is possible to form aluminum UNO, also V, 1. Aluminum UNO, alloy plate or Ti foil.

In particular, since it is possible to form a film on a commercially available aluminum plate having a thickness of 20 to 39 pm with suitable holes tl' to a thickness almost equal to the thickness of the foil, the weld angle T of the substrate l and tJ- min-#f# is easy.

Then, aluminum substrate or aluminum alloy substrate I
K is subjected to, for example, degreasing using alkaline degreasing, chemical polishing using a depleted phosphate chemical polishing solution, desmutting, and pre-treatment of the water washing pipe 53p11.

Furthermore, as shown in No. J Doujin, for example, the anode r1~ is completely formed with an acidic solution such as sulfuric acid, and as shown in Fig. 2 (A).
Aluminum Uno, u+1; one side of aluminum Uno alloy substrate 1 (hereinafter referred to as substrate 1) &, l: -Jil;
Porous aluminum oxide with a thickness of l~100/l trr in most of the layers, I'J, hypodermis 1 (
〆'Q 2 l, do). Holes 2 in this film 2
1) kJ, 1γ■ diameter is 001 to 0.1μ full,
The depth is approximately equal to the IF5 of the coating 2, t:1, and they are aligned in the aluminum oxide UNO 2a at intervals of 0.03 to 12 pt perpendicular to the coating surface.

The anodic oxidation bath and anodic oxidation product consist of a porous aluminum oxide film 2 with a pore structure perpendicular to the surface of the substrate 1 and parallel to each other.
It is an acidic liquid mainly composed of one or two of sulfuric acid, chloro, I'f, oxalic acid, and phosphoric acid.
For each bath, the appropriate anodizing temperature is set. General anodizing conditions and 1. Temperature 0.5-1 from 0 to 40℃
Current density of 0 /dn/.

DC or AC waveforms and air 7H, stirring are suitable.

Subsequently, as shown in Figure 1B, AC plating is carried out in a plating bath containing gold-flexible salts such as cobalt sulfate, and the pores of the coating 2 are removed as shown in Figure 2N. 2+) and ferromagnetic gold scraps or ferromagnetic alloy 3 (hereinafter ferromagnetic material 3)
) is completely precipitated, and the holes 21) are sufficiently filled. This electroplating is carried out using an aqueous solution plating bath containing two or more types of iron salt, cobalt salt, and nickel A-salt 111 Hmata #J to deposit 3fiH ferromagnetic material, at a temperature of approximately 10 to 40°C,
The plating process is carried out under the conditions of plating with a plating voltage of around 150°C, and the pores 2b of the porous aluminum oxide are completely filled with the TVii material.

Thereafter, the substrate J and the film 2 are separated by dissolving or the like as shown in FIG.
As shown, only the skin BfA2 was obtained, and this film 2 was pulverized by various methods to obtain a fine powder 4, which is a magnetic powder, as shown in Fig. 12 and Fig. 1).

1. When pulverizing the coating 2, the ti base 1 and the coating 2 may be pulverized without being completely separated.The specific method for removing pulverization during the pulverization process is as follows.

(1) (F'LtiJ, J'Nsu30 p tn
LDf'+? x-shaped substrate i (7) case e''.

J9 is anodized so that most of it becomes an aluminum oxide film 2, and holes 21) in the film 2 are formed.

The magnetic material 3-C4'J is almost filled with air plating.

In this case, since the aluminum oxide film covering some parts of the base is sufficiently brittle, there is no need to remove the remaining base, and the aluminum oxide film is crushed.

(2) One part of the substrate was soaked in a saturated mercuric chloride solution (Uruibasha, OWt JI) to a thickness of about 5 μm to 0.2 μm.
I; body I'! Dissolve only the Is component, take out only the intoxicant, aluminum Uno, and magnetic film 2 (A), and remove Minamata 2.仝;、
After drying, crush 1';).

(3) Combine the areas where the remaining substrate 1 is thick;
y (2) Solving power of residual substrate 1 by method ゛t is long time ￥
Therefore, shave JI in chloric acid and methanol ILH solution.
E'<4=, I base material 1 is 1% pole, 1 value is aluminum base N, about 50~650 no? LL HE
Then, the aluminum oxide magnetic film '·() is peeled off from the substrate 1 and pulverized.

The skin j11:\2 obtained by this method is very brittle and easy to grind, so it can be crushed using a common ball mill, stamp mill, jet mill, or vibration mill.

Use a grinder such as an attritor (43+4'4), and adjust the grain size fp, Iya by controlling the settling time, etc.

The magnetic powder obtained by grinding consists of 7g of chemically stable non-magnetic aluminum oxide and many needle-shaped ferromagnetic materials, and each needle-like ferromagnetic material e has a shape anisotropy. Because it is a particle close to a single magnetic domain with a large magnetic field, it exhibits a high coercive force.

The present invention will be described below with reference to Examples.

Actual Mx Example 1 After washing and drying commercially available aluminum W4'C with a thickness of 17 μm with 7 tons or trichloroethylene, an aqueous solution containing 15-thiosulfuric acid was used as an active oxidation bath, and the bath temperature was 15°C and the current density was U1.5/. Sky dr! One side of the aluminum foil was anodized for 30 minutes under direct current using a lead plate '5C under the condition of air (■, stirring).

As a result, a porous aluminum oxide film with a thickness of about 1 (i/I m) was obtained. Next, after washing with water, the bath temperature was lowered in a cook A tometsuki bath containing cobalt pentatysulfate, 2q6113. 25℃, plating voltage 18V *
b 0112 Under the conditions of alternating current and air, the oxidized surface of the rod was plated with cobalt for 40 minutes using a lead plate as the counter electrode, and the pores of the porous aluminum oxide film were plated with precipitated cobalt.
i l'J: Filling ζ. After washing thoroughly with water,
The mixture was ground in ethyl alcohol using a ball mill for 10 minutes. 1)) The size of the resulting powder is well-balanced, and the average particle size is approximately Q, 4 pm. 19
500e teh ft.

Example 2) A commercially available aluminum foil of about 17 ptn was washed with 7 tons or trichlorethylene and dried, and then 15
The bath temperature was 20°C and the current density was ""/dn/.

Under conditions of air agitation, a lead plate was used as the cathode [7 minutes with direct current,
One side of aluminum foil? -Anodized.

This resulted in a porous aluminum oxide film vr- having a thickness of about 4 .mu.m. Next, after washing with water, add 5 cobalt sulfate, 1
% nickel sulfate, 2% phosphoric acid, 0.5% gelatin in a bath at a bath temperature of 25%.
℃, plating voltage J, 5V, 501 bit% air agitation, plating was performed for 10 minutes with a lead plate as the opposite plate, and the porosity was 8 (pores in aluminum oxide film'?r: 47F edge/l/) - nickel. Filled with alloy. After thoroughly washing with water, the film was soaked in a saturated mercuric aqueous solution to dissolve only the remaining B13 aluminum (7゛c aluminum oxide magnetic film jJ fK was obtained.Subsequently, after thoroughly washing the film with water, it was immersed in a saturated mercuric aqueous solution to dissolve only the remaining B13 aluminum. 1 in ethyl alcohol
Milled for 0 minutes. The average particle size of the obtained powder is approximately 0.3μ
Magnetization Pi 18 ” at ηt and 10 KOe.

114. The coercive force t'' was 12000C.

Example 1 Iwa J7 0.5 mm commercially available aluminum plate (#41 degree 9
9.5 cm or more) vc - After pretreatment of alkaline degreasing and chemical polishing under the conditions shown in Table 1 and thorough washing with water, use an aqueous solution containing 15% sulfuric acid and 5% oxalic acid as an anodizing bath and bath temperature 1.
One side of the aluminum plate was anodized with direct current for 50 minutes using the carbon plate as a cathode under the conditions of 0° C., current density of 1.5 A/d, and air stirring of 4 W. This p thickness is about 30/! m
A porous aluminum ceride skin Bijif was obtained. Next, after washing with water, add cobalt trisulfate and iron dithisulfate.

Cobalt-iron alloy plated with 2% boric acid and 0.5% geladine, bath temperature 25℃, men・F iF, pressure t
Plating was carried out for 60 minutes with a lead plate as the counter electrode under conditions of 5 V, 5 o11z AC, air, and stirring, and the pores of the porous aluminum oxide film were filled to the tl with precipitated cobalt-iron alloy. Subsequently, after 1. washing with water and sealing with water, the aluminum plate with the film was energized for 2 seconds at 55 V in a halic acid-methanol solution to oxidize the aluminum plate. Aluminum magnetic film?
'tT1, released well. After that, wash thoroughly with water, dry, and use a ball mill for 10 minutes in alcohol (15).
Shattered. The average particle size t of the obtained powder is approximately Q, 4/l
m, and I Q KOc Ic * k) Z, (+
74 is 20Q rll 11/, coercive force is 22
It was 000e.

As explained above, the magnetic powder V according to the present invention is a novel magnetic powder composed of chemically stable non-magnetic aluminum oxide and a 91-shaped ferromagnetic metal or alloy, and is different from the conventional alloy magnetic powder. It has the advantage of not having disadvantages such as surface instability, powder particle disintegration, and deterioration of magnetic properties due to interparticle interactions. Furthermore, there are needle-shaped ferromagnetic metal particles or ferromagnetic alloy particles aligned in one direction in non-magnetic aluminum oxide. Because there is
The magnetic particles according to the present invention have a high force of 11η, and have the advantage that even if the particle size of the powder is yiA:17, the coercive force does not fluctuate much. How does the present invention produce an amorphous powder that has these advantages? , 12 tl are mostly floating single culms],
Continuous processing is nJ capable, and uniform 'L' is produced without the need for advanced technology! ? The magnetic powder t, J of the present invention having these advantages
: Useful for magnetic recording.

[Brief explanation of the drawing]

Figure 1 and ? P, 2 Diagrams: An example of the method for producing the wood powder according to the invention;
rr, Figure 2 is a cross-sectional diagram showing each processing step of the substrate. In the drawing, 1 is the substrate, 2 is the coating, 2 is aluminum oxide, 2b is the hole, 31d is the ferromagnetic material, 4 is the The number of particles is 1,111, which becomes magnetic powder. October f051' % I?'F Wazu 1412
11 Bow 1] 2fo Yearly Bansha Xshi;
2 Name of the invention Bisexual Song Dynasty and So01+! How to send '3 4.l. (, Incident E. (") Seki 1^l) 1 person, No. 6, 1-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo (422) Japanese Army's TiL Story Public Company 1 - Hit ' Eaves i middle number I()7 G correction target work I if to g nB..□Ill fz f
i';I:'J';'0- IV4□17 Contents of amendment (1) Details v! 1A, 4A, 9th row r high retention power”
is corrected as "High Test fQ Power". (2) Details 8N A, ? u 9 M fn 7th line, 8th line (7JfMetsugi ■ around 150, plating conditions for pressure 3ζ flow) f [Plating electric current around 15V J:E, 9 ?I
Complement plating conditions J and jE for r. (3) In specification 1, ■page 10 cli line 16 I'
Correct 650 J to ra5VJZ). (4) In the drawings, correct Figure 1 to the attached sheet. & Soe Sui Chuku day (≠

Claims (1)

[Scope of Claims] (Magnetic powder having fine particles of porous aluminum oxide whose pores are filled with a ferromagnetic metal or a ferromagnetic alloy. (2) Anodized ftm on an aluminum or aluminum alloy substrate to form a porous Forming an aluminum oxide film, depositing a ferromagnetic metal or ferromagnetic alloy into the pores of the porous aluminum oxide film by electroplating, and filling the pores with the ferromagnetic metal or ferromagnetic alloy. High quality aluminum oxide skin gt - A method for producing magnetic powder, which is separated from the aluminum or aluminum alloy substrate or ground into fine particles without separation.