JPH02125832A - Soft magnetic amorphous alloy foil - Google Patents

Abstract

PURPOSE:To improve the soft magnetic characteristics and workability of the title foil by specifying the contg. atomic rate of iron and cobalt in an alloy and specifying the thickness of foil. CONSTITUTION:Soft magnetic amorphous alloy foil is formed with an alloy contg. iron and cobalt. The contg. atomic ratio of iron and cobalt in the alloy is regulated to >=90% cobalt. The thickness of the alloy foil is furthermore regulated to <=10mum. In this way, the soft magnetic characteristics and workability of the amorphous alloy foil can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an amorphous alloy foil that has excellent magnetic properties, particularly soft magnetism, and is thinner and has better workability than conventional amorphous alloys.

[Conventional technology]

Amorphous alloys have irregular arrangement of metal atoms, lack long periodicity, and have structural specificities compared to crystalline alloys, such as the absence of grain boundaries and lattice defects. There is. Due to these factors, amorphous alloys have excellent magnetic properties.

In particular, applications as low hysteretic loss materials and high magnetic permeability materials are seen as promising. For example, Fe-based amorphous alloys have a high saturation magnetic flux density and are being considered for application as transformer iron cores by taking advantage of their low hysteresis loss characteristics. It is said that losses are significantly smaller and costs can be reduced compared to conventional silicon steel plates. Furthermore, CO-based amorphous alloys have a low coercive force over a wide frequency band, and are used as magnetic cores for magnetic amplifiers.

The most common method for producing amorphous alloys is a rapid cooling method. In this method, molten metal is introduced into a cooled rotating roll and rapidly cooled at 105 to 1106 de/s, thereby solidifying without giving time for crystallization to form an amorphous alloy. However, amorphous alloys produced by the rapid cooling method are currently limited to those having a thickness of several 108 or more due to the manufacturing method. Furthermore, when the molten metal comes into contact with the cooling roll, unevenness occurs on the surface, making it difficult to produce a thin film having a thickness smaller than this. Figure 4 shows the surface condition obtained by the rapid cooling method. The vertical axis shows the unevenness in the film thickness direction, and the horizontal axis shows the length in the film surface direction. It can be seen that the surface in contact with the rolls has significant irregularities compared to the free solidification surface.

Other methods for producing amorphous alloys include sputtering,
Vacuum deposition methods and ion blating methods are being considered. However, these methods have poor productivity for producing amorphous alloys and require expensive manufacturing equipment. Furthermore, the amorphous alloy must be attached to some object, and the amorphous alloy cannot be isolated.

On the other hand, methods for manufacturing amorphous alloys using electrolytic plating and electroless plating are also being studied (Japanese Patent Application Laid-open No. 52140403 and Japanese Patent Application Laid-Open No. 55-164092). Recently, studies have also been conducted on the production of amorphous alloys using pulsed electrolysis (
(Japanese Patent Application Laid-Open No. 60-33382). By making the pulse width short and the duty ratio small, the thickness of the concentration polarization layer of the metal ion near the working electrode can be made thinner, and the critical diffusion current and therefore the overvoltage can be increased, thereby increasing the amorphous is said to be progressing.

However, there is no report on the use of a plating method to produce a cobalt-iron amorphous alloy foil that has excellent soft magnetic properties and is significantly thinner than conventional amorphous alloys.

[Problem to be solved by the invention]

As an industrial product, being able to easily and precisely process it into the desired shape and size plays a major role in not only reducing productivity and cost, but also improving performance. for that purpose,
It is smooth with any thickness, and has excellent versatility in the form of a tape, sheet, or foil. For example, with regard to magnetic heads, as perpendicular magnetic recording type recording media appear in the future, magnetic heads will be required to be made thinner. Furthermore, magnetic cores of magnetic amplifiers and the like are currently required to improve soft magnetic properties such as coercive force in a high frequency region. Generally, when a high-frequency excitation current flows, eddy currents flowing in the magnetic layer increase, resulting in large losses.

Eddy current is proportional to the magnetic layer thickness. However, with amorphous alloys produced by conventional rapid cooling methods, it is not possible to produce amorphous alloys with a diameter of 20 μm or less. Although it is further rolled and used, it still does not become less than about 15 Ja. Therefore, when winding or laminating amorphous alloy tape into a toroidal core shape, the actual volume ratio (space factor) occupied by the material becomes a problem, but due to the unevenness of the surface, it is 80 to 85% compared to silicon steel sheets. This is significantly smaller than 95% of . For this reason, the appearance of amorphous alloy tapes that are an order of magnitude thinner than the current ones and that have significantly improved surface smoothness are awaited.

[Means to solve the problem]

Therefore, the present inventors invented an amorphous alloy foil that contains iron-cobalt that has excellent magnetic properties, especially soft magnetism, is much thinner than conventional amorphous alloys, and has excellent surface smoothness. .

That is, according to the present invention, in an alloy containing iron and cobalt, the atomic ratio of iron and cobalt in the alloy is 90% or more of cobalt, and the thickness thereof is Provided is a soft magnetic amorphous alloy foil characterized in that .

The soft magnetic properties of a magnetic material, especially the coercive force, greatly depend on the magnetostriction of the magnetic material. Furthermore, magnetostriction is generally a function of alloy composition, and among iron-cobalt alloys, cobalt-based alloys have excellent soft magnetic properties. Preferably, the atomic ratio of iron and cobalt in the alloy is 90% cobalt.
The above is good. If the cobalt content is less than 90%, that is, if the iron content is more than 10%, magnetostriction increases, which is not preferable. In particular, when the cobalt content is 94%, the magnetostriction constant becomes almost zero, so this atomic ratio is most preferable. Also,
In addition to cobalt and iron, small amounts of chromium and others (e.g. 1~
2%) can also be included to improve the corrosion resistance of the alloy.

Furthermore, in order to deposit an iron-cobalt alloy in an amorphous state by electrolytic plating or electroless plating, P, B, As,
Ge.

It is necessary to contain a metalloid such as Si, Te or Se. This alloy can generally be represented by the following formula.

(Fe, Co+-x)y(MzM' +-z) +-y
(In the formula, 0≦x, ySZ≦1, X≧0.9, M,
M' is P, B, As, Ge, Si,
It is a metalloid of Te or Se. ) The amorphous alloy foil of the present invention has a thickness of 10p or less. By using the plating method, the surface unevenness can be reduced, so the volume fraction (space factor) of the alloy can be increased.
It also has excellent magnetic permeability and other magnetic properties. In addition, since the thickness is small, eddy currents are generated less and the soft magnetic properties in the high frequency region are excellent.

Of course, the thinner thickness also meets the demand for thinner magnetic heads. Further, the amorphous alloy foil of the present invention can be cut into a desired shape and size and used as it is or in a layered manner depending on the purpose. For example, when used in a magnetic head, it can be produced by cutting a foil-like amorphous alloy smaller than the IO mark into a horseshoe shape and winding it into a coil. When used as a magnetic core for a magnetic amplifier, it can be produced by winding an amorphous alloy foil with long thin slits into a toroidal shape. By making the film much thinner than amorphous alloys produced by rapid cooling, it is possible to suppress the generation of eddy currents in the high frequency range and reduce coercive force.

Furthermore, it is expected that the main body of the magnetic amplifier can be made significantly smaller.

The amorphous alloy foil of the present invention has a surface of 0. An amorphous alloy in the form of a tape or foil can be obtained by peeling off the electrolytically deposited alloy using an electrode polished to a surface roughness of IJJWl or less. The technique of depositing an amorphous alloy on an electrode is disclosed in Japanese Patent Application Laid-open Nos. 52-140403 and 55-16409.
No. 2 and No. 60-33382, etc.,
Methods include depositing metalloids along with metals, or depositing under overvoltage (particularly using pulsed voltage). The thickness of the tape can be easily controlled by the electrolysis time. Furthermore, by using the pulse electrodeposition method, the amount of hydrogen generated can be sufficiently reduced compared to the amount of metal deposited, and hydrogen embrittlement can be prevented (Japanese Patent Application No. 186684/1984). Furthermore, film forming properties can be improved by adjusting current density, duty ratio, pulse width, bias voltage application, etc. Additionally, the addition of a reagent having a reducing effect is also very effective (Patent Application No. 1986-7)
4787 specification).

When the soft magnetic amorphous alloy of the iron-cobalt alloy of the present invention is precipitated by the plating method, the preferred metalloid to be added to the plating bath is P (phosphorus), and the plating bath contains hypophosphorous acid, hypophosphorous acid, etc. Use salts (sodium salts, potassium salts, etc.) or mixtures thereof.

Additionally, electrolytic or electroless plating methods allow the alloy to be plated even if the substrate is non-conductive, as long as the surface is conductive or sensitive to plating.

Therefore, polyethylene, polypropylene, polyacrylonitrile, polyvinyl chloride, polyvinyl alcohol,
The surface of a flexible plastic film made of polyester, polyamide, polyimide, polysulfone, PPS, PPO, polyoxydiazole, etc. is treated to make it susceptible to plating, and the film is rolled up and passed through a plating bath for a predetermined period of time. It is also possible to obtain an amorphous Fe--Co alloy foil with a thickness of 10 mm or less on a flexible plastic film by plating only a thin film.

Then, amorphous Fe formed directly on such an insulator
-Co alloy foil or free-standing amorphous Fe-C.

A magnetic core or other inductor can also be constructed by laminating or winding a laminate of alloy foil and insulating film. In order to improve the high frequency characteristics of the magnetic core, low dielectric constant polymers such as polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, etc. are used as an insulating film, and if necessary, glass fibers, carbon fibers, inorganic reinforcing agents, and ceramics are used. It is better to use a material made from a material containing a filler such as. By interposing the insulator in this way, the generation of eddy current can be prevented or minimized.

[For production]

The amorphous alloy foil of the present invention is made of an iron-cobalt alloy with extremely low or almost zero magnetostriction and is an amorphous alloy with excellent soft magnetism.
By forming the film to a thickness of 0J or less, the film has a large volume fraction and is therefore extremely thin, resulting in significantly improved soft magnetic properties compared to an amorphous alloy thin film produced by the conventional quenching method.
And since it is made of foil, it is easy to use.

〔Example〕

Example Film production of amorphous alloy A Iron chloride (II) 2 g/β, cobalt sulfate (I[) 27
8 g/β, sodium hypophosphite 21 g/#, and halogen acid 6 g/j2 were adjusted to pH 1.4, and the current density was 0.1 A.
Electrolytic deposition was performed at /c++t.

An aqueous plating solution having the above composition is placed in a plating bath, and a voltage is applied between the counter electrode made of platinum and the working electrode to deposit metals on the working electrode. The working electrode surface has a center line surface roughness of 0. It has a mirror finish below IJml and is further finished with hard chrome plating.

The deposited film is immediately peeled off, washed and dried.

The thickness of the deposited film depends on the residence time of the working electrode in the plating solution. The thickness of the amorphous alloy foil obtained after 7 minutes of electrodeposition was 7 mm. Moreover, it had no pinholes and had excellent flexibility.

Film production of amorphous alloy B Iron sulfate (II) 0.2 g/jl', cobalt sulfate (I
I) 27,8 g / R1 sodium hypophosphite 21
g/j! , 6 g/l of halonic acid and 58.8 g/l of sodium citrate) in an aqueous solution of pt1
9.0. Using this, electroless plating was performed on a polyethylene terrestrial film until the film thickness reached 10R1. The bath temperature was 90°C.

The obtained film had specular gloss, no pinholes, and excellent flexibility.

Observation of quality of sample An X-ray analysis chart of amorphous alloy A is shown in FIG. 1st
In the figure, the horizontal axis is the X-ray scattering angle from the sample, and the vertical axis is the scattering intensity. In this way, no peaks due to crystals peculiar to metals are observed, and it is considered that the metal is completely amorphous. Similarly, amorphousization was confirmed for amorphous alloy B as well.

Measurement of Alloy Composition Amorphous alloy A was dissolved in 5-nitric acid, and distilled water was added to the solution.
It was set to 0-. This liquid was quantitatively analyzed using an ICP emission spectrometer (model 1c8P-575MK-II manufactured by Jarrell Ash Japan). As a result, the weight ratio of Fe: Co
The following results were obtained: P=4.8:83.2:12.0 (I2). The atomic ratio of iron and cobalt at this time was 6:94.

Measurement of surface smoothness The surface roughness of the alloy tape was measured using a stylus type surface roughness meter manufactured by Rank Taylor Hovran at a magnification of 50 times in the scanning direction and a magnification of 10,000 times in the roughness direction.
When the center line average roughness was calculated, it was 0.1 cape. (However, the cutoff value is 0.8 mm, and the measurement length is 30 m.
m) Comparative amorphous alloy C manufactured by Japan Amorphous Metal Co., Ltd., Metglas 2605S-2
was used. The specifications of each sample are summarized in the table below.

Table 1 Specifications for each sample Composition Thickness (m) Ra Amorphous alloy A Fe-Co-P 7 0
．． 1 Comparative Sample CFe-B-5i-C252,0 Example 2 Ten sheets of each of Samples A and C were stacked and their wear l was measured, and the volume ratio was calculated using the following formula.

■ The results are shown in Table 2.

Table 2 Volume ratio calculation result A 72.2 97C271
, 890 or more, those with a center line average roughness of 0.5- or less have a high volume fraction, and when used as a magnetic core material, it can be expected that a product with high conversion efficiency and low cost can be obtained.

Example 3 A toroidal core is shown in FIG. 2, and a magnetic permeability measurement circuit is shown in FIG. 4. Each sample A and B was formed into a toroidal shape (ro = 5.0
mm, r, = 3.8 + nm, rl = 2.5 mm)
The primary coil 2 and the secondary coil 3 were each wound 50 times with a 0.2φ enamelled wire, and the magnetic permeability was measured. An alternating current with a constant frequency is passed through the primary coil (2) from an oscillator (4), and the induced electromotive force in the secondary coil (3) is measured using a voltmeter (7). Note that the magnetic permeability was calculated using the following formula.

■ H=0.2N ■ μ-B/H H: Magnetizing force N: Number of coil turns r Nidroidal core radius I: Current B: Magnetic flux density V: Secondary coil generated electromotive force f: Frequency A... Sample cross-sectional area μ: Magnetic permeability The measurement results of magnetic permeability are shown below.

Table 3 Magnetic permeability measurement results Thickness (corridor) Magnetic permeability A 7 35.000c
25 20.000 It can be seen that the sample of the present invention also has excellent magnetic properties.

〔Effect of the invention〕

The amorphous alloy foil of the present invention has improved soft magnetism, excellent workability, and is highly versatile in terms of application.

[Brief explanation of drawings]

FIG. 1 is an X-ray diffraction chart of amorphous alloy A of Example,
FIG. 2 is a schematic diagram showing a toroidal ring shape, FIG. 3 is a schematic diagram showing a magnetic permeability measuring circuit, and FIG. 4 is a chart showing the surface roughness of a rapidly solidified amorphous alloy tape. 1... Toroidal ring, 2... -order coil, 3...
... Secondary Koinope 4... Oscillator, 5... Voltmeter, 6... Amplification integrator, 7... Voltmeter. (16〉 JiI Suspect 1 Rin

Claims (1)

[Claims] 1. A soft magnetic amorphous alloy foil characterized in that an alloy containing iron and cobalt has an atomic ratio of cobalt of 90% or more and a thickness of 10 μm or less.