JPH1112698A - Bias material for magnetic marker, magnetic marker, and manufacture of bias material for magnetic marker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain magnetic properties required of a bias material for magnetic marker and to provide a magnetic marker using the above bias material and a method of manufacture of the above bias material. SOLUTION: Plastic working is applied to a stock so that the stock can be provided with a structure where a Cu-group non-magnetic metal is dispersed in a matrix composed essentially of Fe by the amount not lower than the limit of solid solubility in the equilibrium state at ordinary temp. The stock is worked into a plate-like or linear state and formed into the bias material for magnetic marker. It is preferable to incorporate Cu by 3-35% by weight ratio. This bias material for magnetic marker is combined with a magnetostrictively vibrating metal chip, by which the magnetic marker can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic marker bias material for applying a bias magnetic field to a magnetostrictive metal piece (hereinafter referred to as a magnetostrictive element) serving as a marker, a magnetic marker, and a method of manufacturing the magnetic marker bias material. Things.

[0002]

2. Description of the Related Art A magnetic label is provided for the purpose of preventing theft, grasping the flow of goods, or grasping the kind of goods.
An electronic monitoring system that detects the label as a marker has been proposed. Among them, there is a system using a magnetostrictive material as a marker. For example, Japanese Patent Application Laid-Open No. 8-60312 proposes a technique using an amorphous magnetostrictive material as a marker. A magnetic field is changed by causing a specific amorphous metal magnetostrictive element to resonate and vibrate in an alternating magnetic field. A system for detecting by a pickup coil is disclosed.

[0003] Also, WO96 / 32518 and
In -87237, a constant preliminary magnetic field (bias magnetic field) is applied to the magnetostrictive material, and in this state, an alternating magnetic field having a specific resonance frequency is applied to the magnetostrictive material so that the magnetostrictive material performs mechanical resonance. Some systems have been proposed. According to a method in which a semi-hard magnetic material is used as such a bias material and a bias magnetic field is applied to the magnetostrictive element serving as a marker, the marker can be deactivated without removing the marker by demagnetizing the bias material. Therefore, if a marker is inserted or affixed to an article, for example, when the price of the article is paid, by deactivating the magnetic marker attached to the article, it can be illegally taken out of the article that has been legally purchased. It is possible to identify the article to which the activated magnetic marker is given.

In such an electronic monitoring system,
Although the magnetostrictive material used as a marker is important, selection of a bias material for applying a bias magnetic field to the magnetostrictive material is also important. The bias material must have a higher coercive force than the magnetostrictive material so as not to be demagnetized by the magnetostrictive material, and a material capable of performing magnetization and demagnetization is required. As such a material capable of magnetization and demagnetization, an Fe-Cr-Co-based semi-hard magnetic material represented by Fe-25wt% Cr-10wt% Co is known, and is used for a reed relay or the like. ing.

[0005] An Fe-Cr-Co alloy is also used as a bias material.
It is expensive because it contains a large amount of Co, and its coercive force is 7200 A
/ M, the residual magnetic flux density Br is about 1.1T, and the squareness ratio Br / B8000 represented by the ratio of the magnetic flux density (saturated magnetic flux density B8000) to the residual magnetic flux density Br at an applied magnetic field of 8000 A / m is It is a material that is not so high as about 0.8.

As described above, the bias material is a material that is magnetized and demagnetized. If the coercive force is too high, there is a problem that it is difficult to sufficiently demagnetize the material. Unsatisfactory degaussing leads to malfunction of the electronic monitoring system, which is not preferable.

[0007] Similarly, if the squareness ratio and the steepness of magnetization in the BH curve are poor, the boundary between the magnetized state and the demagnetized state is not clear, which also causes a malfunction. The magnetization steepness referred to in the present invention refers to a characteristic in which the magnetization state changes abruptly when the bias material is magnetized or demagnetized. In a material having excellent magnetization steepness, a material having a BH curve close to a rectangle is considered. Become.

The determination of the superiority of the magnetization steepness in the present invention will be described below. It is generally said that a semi-hard magnetic material reaches a saturation magnetization when a magnetic field five times its coercive force is applied. Therefore, this amount of magnetization will be referred to as B (5Hc). Further, the amount of magnetization when a magnetic field 1.5 times the coercive force is applied is defined as B (1.5Hc), and the ratio thereof, that is, B (1.5Hc) / B (5Hc) exceeds 0.8. The material was made of a material having excellent magnetization steepness.

It is convenient for applying a bias magnetic field to the magnetostrictive element that the residual magnetic flux density is as high as possible.
In the case of the -Cr-Co alloy, the value is significantly lower than that of pure iron of 2.1T. The magnitude of the bias magnetic field applied to the magnetostrictive element is proportional to the residual magnetic flux density and the cross-sectional area of the bias material. If the residual magnetic flux density is small, it is necessary to increase the cross-sectional area of the bias material, which is inconvenient for downsizing the magnetic marker.

[0010] The object of the present invention is to solve the above problems,
An object of the present invention is to provide an inexpensive material having excellent magnetic properties as a bias material for a magnetic marker. Another object of the present invention is to provide a magnetic marker using the bias material.
It is to provide an effective method of manufacturing a bias material.

[0011]

The present inventor has a high residual magnetic flux density and a coercive force required as a bias material for a magnetic marker, and realizes a high squareness ratio in a BH curve and excellent magnetization steepness. As a result of examining inexpensive materials that can be
The e-Cu group material has been reached.

That is, the present invention is a bias material for a magnetic marker having a structure in which one or more kinds of Cu group nonmagnetic metals are dispersed in a matrix mainly composed of Fe. In the present invention, Fe is mainly used when Fe is C, Si,
Minor components such as Mn, P, S, Al, N, O and F
e) contains additional elements that are dissolved in e. Further, in the present invention, since the Cu group nonmagnetic metal has a very low solid solubility in a matrix mainly composed of Fe, except for those that are dissolved in a trace amount in the matrix, they exist alone, Needless to say, it contains trace components. Also,
In the present invention, “dispersion” does not mean dispersion at the atomic level, but means that a phase is formed in a material.

The matrix mainly composed of Fe contains C
A bias material for a magnetic marker having a structure in which one or more kinds of u-group nonmagnetic metals and a nonmagnetic inorganic compound are dispersed.

In the present invention, a metal carbide is preferably dispersed as the nonmagnetic inorganic compound.

In the present invention, the Cu group nonmagnetic metal preferably contains 3 to 35% by weight of Cu.

If the coercive force is too small, the magnetization state of the bias material becomes unstable. Therefore, the lower limit of the Cu content is more preferably 5% by weight or more. Also, if the coercive force is too large, it becomes difficult to demagnetize the bias material,
A more preferable upper limit of the amount of Cu is 25% or less by weight. A more preferable range of the amount of Cu is 8 to 18% by weight.
It is.

The bias material for a magnetic marker of the present invention is flattened or linearized by plastic working.

In the bias material of the present invention, the Cu group non-magnetic metal is expanded by plastic working.

The biasing material of the present invention has magnetic anisotropy due to the expanded Cu non-magnetic metal.

The bias material of the present invention can enhance the sharpness of magnetization by heat treatment after plastic working.

The bias material of the present invention is cut out in parallel with the spread Cu group non-magnetic metal in order to utilize the magnetic anisotropy.

The bias material for a magnetic marker of the present invention is made of Fe
Can be obtained by plasticizing and flattening or linearizing a molten material in which one or more Cu group non-magnetic metals are contained in a matrix mainly composed of at least the solid solubility limit at room temperature in an equilibrium state. .

Alternatively, the bias material for a magnetic marker of the present invention can be obtained by flattening or linearizing a material obtained by binding a mixed powder by consolidation or sintering by plastic working. In the smelting method, the Cu group non-magnetic metal aggregates at the matrix grain boundaries during hot working and may cause cracking. However, in the method using powder, the Cu group non-magnetic metal aggregates at the matrix grain boundaries. Can be prevented, which is preferable.

Alternatively, the bias material for a magnetic marker of the present invention is characterized in that metal particles containing one or more Cu group nonmagnetic metals in a matrix mainly composed of Fe or more in a state of equilibrium at room temperature in a solid solution limit or more are combined. The obtained material can be obtained by flattening or linearizing by plastic working. The method of using such metal particles is more effective than the method of using a mixed powder as a material because the Cu group nonmagnetic metal can be finely dispersed.

In the present invention, for bonding metal particles, a method such as consolidation, sintering, or lamination in a semi-solid state can be adopted. Specifically, after obtaining a metal powder by an atomizing method such as gas atomizing and water atomizing,
A method of compacting by hot isostatic pressing (hereinafter referred to as HIP) or lamination by spray forming is preferable. The term “stacking” as used herein refers to spraying a melted material into a semi-solid state, and stacking and solidifying particles.

To improve mass productivity, it is effective to increase the material. Therefore, at the beginning of the plastic working, hot working is effective. Specifically, forging or hot rolling can be employed.

In order to increase the steepness of magnetization of the bias material, it is effective to have magnetic anisotropy. In order to spread the dispersed Cu group non-magnetic metal in one direction, it is preferable to use cold working in the latter stage of plastic working. Specifically, cold drawing or cold rolling can be employed.

In order to further increase the magnetization steepness, it is preferable to perform a heat treatment (hereinafter referred to as a steepening heat treatment) after the cold working. The main factors that hinder the rotation of the magnetic domains of the matrix are the dispersed non-magnetic regions of the Cu group non-magnetic metal and the non-magnetic inorganic compound, and the strain of the matrix applied by plastic working. Since the strain is removed from the matrix by the steepening heat treatment, the rotation of the magnetic domain of the matrix becomes easy. Therefore, the main element that hinders the rotation of the magnetic domain can be limited to the Cu group non-magnetic metal and the non-magnetic inorganic compound, and the magnetization steepness can be enhanced.

The temperature of the steepening heat treatment is 400 to 700 ° C.
Is preferred. If the heat treatment temperature is too low, the strain of the matrix cannot be sufficiently removed. Therefore, a more preferable heat treatment temperature is 450 ° C. or higher. If the heat treatment temperature is too high, the Cu group nonmagnetic metal may be coarsened, and the effect of preventing magnetic domain rotation of the matrix may not be sufficiently obtained. Therefore, a more preferable heat treatment temperature is 650 ° C. or less.

The time for the heat treatment for steepening is 2 to 120.
Minutes are preferred. If the heat treatment time is too short, the matrix strain cannot be sufficiently removed. Therefore, a more preferable heat treatment time is 3 minutes or more. If the heat treatment time is too long, the Cu group non-magnetic metal may be coarsened, and the effect of preventing magnetic domain rotation of the matrix may not be sufficiently obtained. Also, from the viewpoint of productivity, it is preferable that the heat treatment time is as short as possible. Therefore, a more preferable heat treatment time is 60 minutes or less.

In order to reduce the size of the magnetic marker, the magnetostrictive element and the bias material are preferably flat or linear.

The present invention is directed to a longitudinal direction of a thin plate material having a structure in which 8 to 18% by weight of a free Cu group non-magnetic metal phase is spread and dispersed in a streak form in a matrix mainly composed of Fe. This is a bias member for a magnetic marker cut out in parallel, that is, in parallel with the muscular tissue.

In the bias material for a magnetic marker of the present invention, when a magnetic field 1.5 times the coercive force is applied in the longitudinal direction of the bias material, the magnetization amount B (1.5 Hc) and the magnetic field 5 times the coercive force are generated. The ratio with the amount of magnetization B (5Hc) when applied, that is, B (1.5Hc) / B (5Hc) exceeds 0.8.

The bias material for a magnetic marker of the present invention can be used as a magnetic marker by combining it with a magnetostrictive element.

In order to reduce the size of the magnetic marker, the magnetostrictive element and the bias material are preferably flat or linear.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the important features of the present invention is that, as described above, a material in which a Cu-based nonmagnetic metal is dispersed in a matrix mainly composed of Fe is selected as a material for applying a bias magnetic field. It is in.

For a matrix mainly composed of Fe, C
The u-group elements, ie, Au, Ag, and Cu, hardly form a solid solution, and have a structure in which the matrix mainly composed of Fe and the Cu-group elements are released. The term “relaxation” as used herein refers to a state in which a phase mainly composed of Fe and a Cu group phase are separated into two phases. When the material is magnetized, the non-magnetic Cu group elements present in a dispersed manner prevent the rotation of the magnetic domains of the magnetic matrix, so that the coercive force increases, and therefore semi-hard magnetism can be imparted. .

As the Cu group nonmagnetic metal, Au, Ag,
It is considered that any of the elements or the use of a plurality of kinds of Cu is effective. However, since Cu can be obtained at the lowest cost among the Cu group, Cu should be used. Is preferred. Since the Cu group metal is dispersed in the bias material to form a non-magnetic region, volume, not weight, is important. Therefore, in order to obtain the same effect, the use of Cu is effective because Cu is smaller than in the case of using Au or Ag.

In the present invention, Cu is preferably contained by 3 to 35% by weight. A more preferable Cu content is 5 to 25% by weight. A more preferable Cu content is 8 to 18% by weight.

If the coercive force of the bias material is too small, the magnetization state of the bias material becomes unstable. For example, there is a possibility that after an article is properly purchased and the biasing material applied to the article is once demagnetized, the magnet is approached and the biasing material is magnetized again, so that an alarm is activated. Therefore, in the present invention, the Cu content is desirably 3% or more by weight. More preferably, the Cu content is 5% or more by weight so that the squareness ratio Br / B8000 exceeds 0.9. In order to achieve coercive force Hc ≧ 1600 [A / m], the more preferable amount of Cu is 8% or more by weight.

On the other hand, if the coercive force is too large, the bias material is difficult to demagnetize, and the distance from the apparatus cannot be increased when demagnetizing. For example, when performing demagnetization at a cash register, it takes time and congestion. There is fear. Further, there is a possibility that the alarm is activated without the bias material being sufficiently demagnetized. Also, by increasing the amount of Cu,
In some cases, the residual magnetic flux density is too low, and the performance as a bias material is lowered. Therefore, in the present invention, Cu
The amount is desirably 35% or less by weight. Squareness ratio Br /
More preferable C so that B8000 does not fall below 0.8.
The u amount is not more than 25% by weight. A more preferable amount of Cu is 18% or less by weight so that the residual magnetic flux density does not fall below 1.3 [T].

The bias material of the present invention has an advantage that the high saturation magnetic flux density of the matrix can be utilized as it is by dispersing the Cu group non-magnetic metal in the matrix mainly composed of Fe. The coercive force can be adjusted by the amount of the Cu group to be dispersed.

Further, by dispersing a non-magnetic inorganic compound in addition to the Cu group non-magnetic metal, the coercive force can be increased, so that the desired coercive force can be easily adjusted. The non-magnetic inorganic compound referred to in the present invention is, for example, MnS
And metal oxides such as Al ₂ O ₃ and metal carbides such as MoC and NbC. Metal carbides are particularly effective because carbon dissolves in a matrix mainly composed of Fe, increases the coercive force of the matrix, and forms carbides with other metal elements. It goes without saying that a nonmagnetic inorganic compound other than the above may be used.

The following elements can be added for adjusting the coercive force. It is preferable to add in the range shown below so that the processability does not decrease. C ≦ 1%, Si ≦ 5%, Mn ≦ 6%, Co ≦ 10%, C
r ≦ 10%, Ta ≦ 5%, W ≦ 5%, Mo ≦ 5%, Ti
≦ 5%, V ≦ 5%, Nb ≦ 5%, P ≦ 0.04%, S ≦
0.03%, Mg ≦ 5%, Ca ≦ 5%, Al ≦ 5%, O
≦ 0.5%, N ≦ 0.5%, B ≦ 1%, Y ≦ 0.5%,
Rare earth element ≦ 0.15%, Pd ≦ 3%, Pt ≦ 3%, Z
r ≦ 0.5%,

Mo, Ta, W, Nb, V, etc., which are particularly effective as elements which form carbides which are finely precipitated in crystal grains which are effective in adjusting the coercive force, are provided. However, when the amount of addition increases, the processability decreases. Further, the squareness ratio and the steepness of magnetization are deteriorated, and the characteristics required as a bias material are deteriorated. Therefore, it is desirable that the amount of addition be in the above range.

When plastic working is applied to a material in which the Cu group is dispersed, an anisotropy is generated in the structure, and thus a magnetic anisotropy is generated. That is, the C dispersed in the matrix
By extending the u-group by plastic working such as rolling or drawing, a structure in which non-magnetic regions extending in the longitudinal direction are dispersed is obtained. When the bias material is magnetized or demagnetized, the non-magnetic region prevents rotation of the magnetic domain, and thus the longitudinal direction becomes the direction of easy magnetization.

FIG. 1 shows the structure of the bias material. The results obtained by observing the microstructure with a scanning electron microscope are shown in (A), and the schematic diagram is shown in (B). As shown in the schematic diagram, a Cu group non-magnetic metal 2 is dispersed in a matrix 1 mainly composed of Fe so as to extend in a rolling direction. Further, a non-magnetic inorganic compound 3 is also observed. According to the X-ray analysis, the black portion in the background is a matrix mainly composed of Fe containing Si, Mn, etc., the streak-like or dot-like white portion is Cu, and the black spherical portion is metal carbide. It was confirmed.

As a method of flattening or linearizing to have magnetic anisotropy, rolling or drawing is effective, but hot rolling, cold rolling or cold rolling is preferred for reasons of shape accuracy, economy and the like. It is desirable to use rolling. Also, it goes without saying that the magnetic marker bias material of the present invention can be used not only in a flat plate shape but also in a linear shape having a round, angular or irregular shaped cross section.

In order to effectively utilize the above-described magnetic anisotropy, it is preferable that the bias material of the present invention is cut in parallel with the extended non-magnetic region of the Cu group and magnetized in the longitudinal direction. Since the nonmagnetic regions are dispersed in a streak shape in the longitudinal direction of the rolling or drawing, the parallel direction is more easily magnetized than the perpendicular direction. This is preferably cut out as the longitudinal direction of the bias material, magnetized in this direction, and used as a bias material for a magnetic marker. Thus, the bias material applies a magnetic field to the magnetostrictive element in the longitudinal direction. Preferably, one of the magnetostrictive elements is subjected to a heat treatment so as to align magnetic domains in the width direction. By bringing the bias material close to each other, the magnetic domain of the magnetostrictive element having a small coercive force easily rotates, and therefore mechanically resonates when exposed to an alternating magnetic field having a unique frequency determined by its length.

In the present invention, it is considered that the method of producing a bias material in a process using an ingot material is a method of obtaining the material at the lowest cost. A method of casting a molten metal into a mold, a method of continuously casting a thin plate directly, and the like can be given. The continuous casting method is preferable because segregation in the material can be suppressed. By applying processing such as rolling or drawing to the obtained ingot material, it is possible to obtain a structure in which non-magnetic regions are dispersed in a streak shape in the longitudinal direction.

The above structure and magnetic behavior can be obtained not only by ingots but also by powder metallurgy materials. Although various combinations of powders can be considered, it is preferable to use metal particles mainly composed of Fe and Cu group nonmagnetic metal particles or particles containing Cu group nonmagnetic metal. By applying a process such as rolling or drawing to a material obtained by binding these alloy powders by consolidation, sintering, or the like, a structure in which nonmagnetic regions are dispersed in a streak shape in the longitudinal direction can be obtained.

Further, according to the method using powder, it is easy to adjust the degree of dispersion of the Cu group nonmetallic element. Therefore, the adjustment of the coercive force is facilitated, and the required coercive force can be obtained with a smaller amount of Cu as compared with the melting method.

In the case of the melting method, since the Cu group non-metal element is concentrated and precipitated at the matrix grain boundaries, cracks may occur during hot working. However, the method using powder prevents such cracks. be able to.

Alternatively, it can also be obtained by using a powder in which a Cu group non-magnetic metal is contained in a matrix mainly composed of Fe at or above the solid solubility limit in an equilibrium state at room temperature. First,
A molten metal containing a Cu group non-magnetic metal in a matrix mainly composed of Fe at or above the solid solubility limit in an equilibrium state at room temperature,
The powder obtained by the quenching method called gas atomization or water atomization is used as a material by consolidation and pressure sintering typified by HIP, or a method of depositing a molten metal in a semi-solid state typified by spray forming, etc. Obtain the material to be processed. By applying a process such as rolling or drawing to the obtained material, a structure in which nonmagnetic regions are dispersed in a streak shape in the longitudinal direction can be obtained. There is an advantage that the Cu group nonmagnetic metal can be finely dispersed as compared with the case of using the mixed powder.

The plastically processed material obtained as described above contains many strains in the matrix. By applying an appropriate heat treatment to remove the distortion, the magnetization steepness can be further increased. FIG. 2 shows the results of measuring the magnetic properties before and after the steepening heat treatment. The curve before the heat treatment shown on the left has a gentle curve, whereas the curve after the heat treatment shown on the right has a shape close to a rectangle. B (1.5Hc) / B (5Hc) representing the magnetization steepness was about 0.8 before the heat treatment, but was improved to about 0.9 after the heat treatment. As described above, it is possible to significantly improve only the magnetization steepness without greatly affecting the saturation magnetic flux density and the coercive force. Also, this steepening heat treatment may be performed before or after the step of cutting out the bias material, but there is no significant difference in the effect. However, from the viewpoint of productivity, the heat treatment is performed so that the heat treatment can be performed continuously. It is preferably performed before.

As described above, it is possible to obtain a thin plate-like magnetic marker bias material cut in parallel with the Cu group nonmagnetic metal phase which has been spread and dispersed in a streak shape.

By cutting out in parallel to the Cu group non-magnetic metal phase which has been spread and dispersed in a streak shape, and subjected to a steepening heat treatment, a bias material of B (1.5Hc) / B (5Hc) ≧ 0.8 is obtained. can get. In particular, those containing 8 to 18% of Cu by weight are B (1.5Hc) / B (5Hc) ≧ 0.9.
Can be easily realized. From various viewpoints such as magnetic properties such as squareness and coercive force, hot and cold workability other than the magnetization steepness, the most preferable Cu amount is 8 to 1 in weight ratio.
8%.

In the present invention, a magnetic marker can be obtained by combining a magnetostrictive element and a bias material.
As the material of the magnetostrictive element, for example, Fe-Co based, Fe-
Ni-Mo based amorphous metal materials and the like are known. Magnetostrictive elements made of these materials can be 3
In a state where the magnetism is preliminarily magnetized to about 100 to 800 A / m, it resonates mechanically by an alternating magnetic field having a resonance frequency determined by the length of the magnetostrictive element. For example, when the resonance frequency is set to 50 to 60 kHz, which is commonly used, the length of the magnetostrictive element can be set to about 20 to 50 mm.

The magnitude of the magnetic field applied to the magnetostrictive element by the bias member is determined by the residual magnetic flux density of the bias member, the sectional area of the bias member, and the distance between the bias member and the magnetostrictive element. Since the bias material of the present invention has a high residual magnetic flux density, the cross-sectional area can be reduced when a bias magnetic field is applied to the magnetostrictive element, which is also effective for reducing the size of the magnetic marker.

According to the shape of the bias material, the magnetostrictive element is also preferably flat or linear. It is more preferable that both the bias material and the magnetostrictive element are formed in a flat plate shape because the size and thickness can be reduced.

[0061]

DETAILED DESCRIPTION OF THE INVENTION Nos. 1 to 16 were produced by a melting method in the following steps. After being adjusted to a desired composition in a melting furnace, ingots were formed to obtain a raw material for melting. Some of the ingots were cracked when forged, but the portions without cracks were processed to a thickness of 5 mm by plastic working by hot rolling. Thereafter, plastic working by soft annealing and cold rolling was repeated to flatten the plate, and a thin plate having a thickness of 50 μm was obtained. Comparative Example 31 was similarly manufactured.

Further, the bias material No. 51-66
Was manufactured by the powder process in the following steps. First, after adjusting to the desired composition in the melting furnace, among various quenching methods,
A spherical powder was obtained by a gas atomizing method. X-ray analysis of this metal powder confirmed that the Cu group nonmagnetic metal was contained in the matrix mainly composed of Fe at or above the solid solubility limit in an equilibrium state at room temperature. Next, the -16 mesh powder obtained by classification was used for a width of 100 mm and a thickness of 40 m.
m, a HIP can made of mild steel having a length of 200 mm, heated and degassed, and then heated at a temperature of 950 ° C. and a pressure of 1500 atm.
For 1 hour to obtain a material. After sintering, the container was directly subjected to plastic working by hot rolling, and then the container was removed by grinding. Subsequently, after softening annealing at 850 ° C. for 1 hour, plastic working was performed to a thickness of 5 mm by hot rolling. Thereafter, plastic working by soft annealing and cold rolling was repeated to flatten the plate, and a thin plate having a thickness of 50 μm was obtained. Comparative Example 81 was manufactured similarly.

Table 1 shows the composition of the bias material manufactured according to the present invention.

[0064]

[Table 1]

From the thin plate material obtained in the above-mentioned step, a test piece for measuring the magnetic properties of a bias material for a magnetic marker was cut out parallel to the rolling direction so as to be parallel to the expanded Cu. Subsequently, after performing a steepening heat treatment at 400 to 700 ° C. for 30 minutes, the magnetic characteristics were measured. Table 2 shows the measurement results of the magnetic properties.

[0066]

[Table 2]

As shown in Table 2, the bias material N of the present invention
o. Nos. 1 to 16 and Nos. It can be seen that in Nos. 51 to 66, the coercive force, residual magnetic flux density, squareness ratio and steepness in the BH curve can be adjusted by the amount of Cu. Cu3 to 35
%, Hc = 800 to 6550 A / m, and the squareness ratio is Br /
B8000 ≧ 0.8, B (1.5Hc) / B (5Hc)
A bias material of ≧ 0.8 can be obtained.

The microstructure of the bias material of the present invention was observed using a scanning electron microscope. The microstructure of the bias material having the chemical composition of the present invention has a structure in which a Cu group nonmagnetic metal is dispersed in a matrix mainly composed of Fe. In the case where a carbide-forming element is added as shown in FIG.
Could be confirmed. One example of the microstructure is shown in FIG. (A) is a bias material No. produced by a melting method. 11
(B) is a microstructure of Bias Material No. produced by a powder method. 60 microstructures. In each case, Cu is dispersed in the form of white stripes or dots in a matrix mainly composed of Fe that looks dark. The horizontal direction of the photo is
This is the longitudinal direction of the bias material. Since the streak-like Cu extends in the lateral direction and coincides with the longitudinal direction of the cold rolling, it can be seen that it has magnetic anisotropy.

Actually, the test piece for measuring the magnetic properties of the magnetic marker bias material was cut out in the width direction of the cold-rolled material, that is, perpendicularly to the expanded Cu, and in the longitudinal direction of the cold-rolled material. That is, a comparison was made with the case of cutting out in parallel with the expanded Cu. Although there is no significant difference in the saturation magnetic flux density or the coercive force, the magnetization steepness is overwhelmingly superior when cut out in parallel, and B (1.5Hc) / B (5H
c) is, for example, the bias material No. of the present invention. In the case of No. 9, the ratio was 0.19 in the vertical member and 0.92 in the parallel member.

The bias material of the present invention was combined with a magnetostrictive vibrating metal piece called a magnetostrictive element to form a magnetic marker. FIG. 4 is a schematic diagram showing an example of the magnetic marker of the present invention. A pack 5 in which a magnetized bias material 4 is sandwiched between resins is brought close to a magnetostrictive element 6 as shown in FIG. This magnetic marker is used by being inserted or pasted into an article.

[0071]

According to the present invention, by using a Fe-Cu group material, a sufficient coercive force and a high residual magnetic flux density as a bias material for a magnetic marker, a high squareness ratio and a steepness in a BH curve are obtained. Can be obtained, and there is no need to use expensive raw materials such as Co. Therefore, it is effective in reducing the cost particularly for a marker that is consumed together with the product.

[Brief description of the drawings]

FIG. 1 is a view showing a result of measuring magnetic properties of a magnetic marker bias material of the present invention.

FIG. 2 is a micrograph of a metal microstructure of a magnetic marker bias material of the present invention and a schematic diagram thereof.

FIG. 3 is a microscopic metal microstructure photograph of the magnetic marker bias material of the present invention.

FIG. 4 is a diagram showing an example of the structure of a magnetic marker incorporating the magnetic marker bias material of the present invention.

[Explanation of symbols]

1 Matrix mainly composed of Fe, 2 Cu group nonmagnetic metal, 3 Nonmagnetic inorganic compound, 4 Magnetic marker bias material, 5 pack, 6 Magnetostrictive element, 7 case

Claims (22)

[Claims] 1. A bias material for a magnetic marker, wherein the bias material has a structure in which one or more Cu group nonmagnetic metals are dispersed in a matrix mainly composed of Fe. 2. A bias material for a magnetic marker, characterized in that it has a structure in which one or more kinds of Cu group nonmagnetic metals and a nonmagnetic inorganic compound are dispersed in a matrix mainly composed of Fe. 3. The bias material for a magnetic marker according to claim 2, wherein the nonmagnetic inorganic compound is a metal carbide. 4. A Cu group nonmagnetic metal having a weight ratio of 3
The bias material for a magnetic marker according to any one of claims 1 to 3, wherein the bias material contains up to 35% of Cu. 5. The bias material for a magnetic marker according to claim 1, wherein the bias material is flattened or linearized by plastic working. 6. The bias material for a magnetic marker according to claim 1, wherein the Cu group non-magnetic metal is expanded. 7. The bias material for a magnetic marker according to claim 1, wherein the bias material has magnetic anisotropy due to the Cu group non-magnetic metal. 8. The bias material for a magnetic marker according to claim 1, wherein the sharpness of magnetization is increased by heat treatment after the plastic working. 9. The bias material for a magnetic marker according to claim 1, wherein the bias material is cut in parallel with the extended Cu group nonmagnetic metal. 10. The bias material for a magnetic marker according to claim 1, wherein the bias material is made of an ingot. 11. The bias material for a magnetic marker according to claim 1, wherein the bias material is flattened or linearized using a material obtained by binding powder by consolidation or sintering. 12. A matrix mainly composed of Fe contains C
10. The method according to claim 1, wherein metal particles containing one or more of the u-group nonmagnetic metals in a state of equilibrium at room temperature or higher are used, and are flattened or linearized.
The bias material for a magnetic marker according to any one of the above. 13. The bias material for a magnetic marker according to claim 12, wherein the metal particles are metal powder obtained by a quenching method. 14. A sheet material having a structure in which one or more phases of a free Cu group nonmagnetic metal in a matrix mainly composed of Fe and containing 8 to 18% by weight of a free phase are dispersed in a streak shape. A bias material for a magnetic marker, wherein the tissue is streaked in a longitudinal direction of the thin plate material. 15. A magnetization amount B (1.5 Hc) when a magnetic field 1.5 times the coercive force is applied in the longitudinal direction of the thin plate, and a magnetization amount B when a magnetic field 5 times the coercive force is applied. The bias material for a magnetic marker according to claim 14, wherein the ratio to (5Hc), that is, B (1.5Hc) / B (5Hc) exceeds 0.8. 16. A magnetic marker comprising a combination of a metal piece that performs magnetostrictive vibration and a bias material that applies a bias magnetic field to the metal piece, wherein the bias material is used as the bias material.
A magnetic marker using the bias material according to any one of the above. 17. The magnetic marker according to claim 14, wherein the metal piece is flat or linear. 18. A matrix mainly composed of Fe contains C
The method comprises flattening or linearizing, by hot and cold plastic working, an ingot containing one or more kinds of u-group nonmagnetic metals at or above the solid solubility limit in an equilibrium state at room temperature. Of manufacturing bias material for magnetic markers. 19. A matrix mainly composed of Fe contains C
A method for producing a bias material for a magnetic marker, comprising flattening or linearizing a metal particle containing one or more kinds of u-group nonmagnetic metals in a state of equilibrium at room temperature or higher in a solid solubility limit. 20. The method according to claim 19, wherein the metal particles are metal powder obtained by a quenching method. 21. A method for manufacturing a bias material for a magnetic marker, comprising applying a heat treatment for increasing the steepness of magnetization after flattening or linearizing by plastic working. 22. The heat treatment has a holding temperature of 400 to 70.
The method for producing a bias material for a magnetic marker according to claim 21, wherein the temperature is 0 ° C.