JPH03255603A - Manufacture of junction ferrite - Google Patents

Abstract

PURPOSE:To make it possible to manufacture junction ferrite using a furnace of ordinary atmosphere, and to contrive both improvement in productivity and reduction in cost by a method wherein a hydroxide selected from K, Rb and Cs is provided on the junction interface between single-crystal ferrite and polycrystalline ferrite. CONSTITUTION:A hydroxide 3, selected from K, Rb and Cs, is provided on the junction interface of polycrystalline ferrite 2 of the junction ferrite consisting of single-crystal ferrite 1 and polycrystalline ferrite 2, and junction ferrite is manufactured by pressure-welding the above-mentioned material. The heat treatment temperature when a junction operation is conducted should be 1220 to 1330 deg.C, and the pressurizing force should be 0.1 to 10kg/cm<2>. For example, potassium hydroxide, rubidium hydroxide, the aqueous solution of cesium hydroxide, or alcoholate solution and the like can be used as the hydroxide of K, Rb and Cs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a bonded ferrite composed of a single-crystal ferrite and a polycrystalline ferrite, which is used, for example, in a composite magnetic head.

[Summary of the invention]

The present invention provides a method for manufacturing a bonded ferrite consisting of a single crystal ferrite and a polycrystalline ferrite, in which Rb is added at least to the matching interface of the polycrystalline ferrite.

By heat-pressing with at least one hydroxide selected from Cs interposed, it is possible to suppress single crystallization and grain growth of polycrystalline ferrite during heat treatment, and to produce a good bonded ferrite. .

[Conventional technology]

Recently, in magnetic heads such as video heads, in order to reduce sliding noise and improve C/N, the conventional single-crystal ferrite head has been replaced by a composite type made of bonded ferrite of single-crystal ferrite and polycrystal ferrite. The head is being replaced. Furthermore, there is a need to reduce the cost of this junction ferrite.

In order to cope with this, bonded ferrite is made by temporarily bonding a mirror-polished single crystal ferrite and a mirror-polished polycrystalline ferrite with water (HzO) or nitric acid (HNO3), and then hot pressing, that is, reduction with N2, etc. It was manufactured by heat treatment at 1220° C. for 2 hours without applying pressure in an atmosphere.

[Problem to be solved by the invention]

In the method for manufacturing bonded ferrite described above, ■ When bonding is performed at a temperature exceeding 22o''C, the polycrystalline ferrite begins to become a single crystal at the interface between the single-crystal ferrite and the polycrystalline ferrite (hereinafter referred to as the "single-crystalline-polycrystalline ferrite interface"). The crystal-polycrystalline ferrite interface moves randomly.Also, grain growth of the polycrystalline ferrite occurs.These must be suppressed as much as possible.

However, the conventional method for manufacturing bonded ferrite has the following problems.

(i) Since the bonding temperature is about 1220°C, the bonding strength does not increase. In other words, increasing the bonding temperature improves the bonding strength, but conversely, growth of 5 single crystals of polycrystalline ferrite occurs, so the conventional bonding temperature of 1220"C is a compromise between bonding strength and single crystallization. The temperature is just at the limit.

(ii) Since it is produced by hot pressing, productivity is poor and costs are high.

(ij) At a junction temperature of 1220°C, the single crystallization of polycrystalline ferrite is about 10 μm, but further control will be required in the future.

On the other hand, as a method of suppressing single crystallization and grain growth of polycrystalline ferrite, a method is to sputter a thin layer of iron oxide, etc. on at least one of the surfaces where single-crystalline ferrite and polycrystalline ferrite are bonded to each other. is also being considered, but in this case, there are problems such as two-point peeling of small holes (uneven bonding at the interface, resulting in spot-like peeling), poor productivity, and increased costs. There is.

In view of the above points, the present invention suppresses single crystallization and grain growth of polycrystalline ferrite, enables bonding at higher temperatures,
The present invention provides a method for manufacturing a bonded ferrite that enables high-quality bonded ferrite to be obtained at low cost.

[Means for Solving the Problems] The present invention provides a method for manufacturing a bonded ferrite consisting of a single crystal ferrite (1) and a polycrystalline ferrite (2), in which +R is added to at least the bonded interface of the polycrystalline ferrite (2).
A bonded ferrite is produced by heat-pressing in the presence of at least one hydroxide (3) selected from b+ Cs (i.e., one or more hydroxides).

The heat treatment temperature during bonding is 1220°C to 1330'
C1 is preferably 1250° C. to 1300° C., and the pressing force thereof is 0.1 to 10 kg/C4.

As the hydroxides of K, Rb, and Cs, for example, an aqueous solution or an Alcolade solution of potassium hydroxide, rubidium hydroxide, or cesium hydroxide can be used.

When the value exceeds , the single crystal-polycrystal ferrite interface moves due to the single crystallization of the polycrystalline ferrite (2).

The above suppressing effect is achieved at a bonding temperature of 1220°C, which is higher than conventional
This is noticeable even at 1330″C, so the bonding strength increases.In addition, it is possible to manufacture bonded ferrite in a normal atmosphere furnace instead of hot pressing, improving productivity.
Cost reduction can be achieved. Of course, according to the present invention, bonded ferrite can also be produced by hot pressing.

[Effect]

At the bonding interface between the single crystal ferrite (1) and the polycrystalline ferrite (2), a small amount of hydroxide (3) selected from Rh and Cs is present during bonding (
That is, during heat treatment), single crystallization and grain growth of polycrystalline ferrite (2) are suppressed. Since the polycrystalline ferrite (2) has little single crystallization, there is little movement at the single crystal-polycrystalline ferrite interface. That is, at a bonding temperature of 1330° C. or lower, the polycrystalline ferrite (2) does not become a single crystal, and the single-crystalline-polycrystalline ferrite interface does not move at all. 1330°C [Example] Hereinafter, an example of the method for manufacturing a bonded ferrite according to the present invention will be described.

Example 1 As shown in Fig. 1, mirror-polished Mn-Zn ferrite single crystal ferrite (1) and polycrystalline ferrite (2)
A 1.0 mol/l KOH aqueous solution (3) prepared by dissolving 56 g of potassium hydroxide (KOH) in 1000 d of water was applied to the interface to temporarily adhere the two. This sample after temporary adhesion (4
), while applying a pressure of 5 kg/cil,
Heat treatment was performed at 1250°C for 2 hours in a 2 atmosphere to produce a bonded ferrite. For comparison, a comparative sample in which water was applied to the interface of single-crystal ferrite (1) and polycrystalline ferrite (2) to temporarily bond them was heat-treated under the same conditions.

The photograph in FIG. 2 shows the bonded state of this sample after heat treatment, in which an aqueous potassium hydroxide solution was applied to the interface between single crystal and polycrystalline ferrite. The photograph in FIG. 3 shows the bonded state of the comparative sample after heat treatment.

In the comparative sample, it is observed that the polycrystalline ferrite is becoming single crystallized from the single-crystalline-polycrystalline ferrite interface.

In this sample (4), in which the potassium hydroxide aqueous solution (3) was applied to the interface between single crystal and polycrystalline ferrite, there was no single crystallization or abnormal grain growth of the polycrystalline ferrite from the interface, and the bond was clean.

The effect of potassium hydroxide aqueous solution on bonded ferrite to prevent single crystallization and to suppress grain growth is remarkable.

Example 2 Mirror-polished Mn-Zn ferrite single crystal ferrite (1) and polycrystalline ferrite (2) were mixed with potassium hydroxide (KOH) dissolved in ethanol at the interface.
A KOH alcoholade solution (3) of mol/l (56 g/l) was applied for temporary adhesion (see Figure 1). This sample (4) after temporary bonding was subjected to heat treatment at 1250° C. for 2 hours in a N2 atmosphere while applying a pressure of 5 kg/clll to produce a bonded ferrite. The photograph in FIG. 4 shows the bonded state of this sample after heat treatment, in which the potassium hydroxide Alcolade solution was applied to the interface between single crystal and polycrystalline ferrite.

In this sample (4) in which the potassium hydroxide Alcolade solution (3) was applied to the interface between single crystal and polycrystalline ferrite, there was no single crystallization or abnormal grain growth of the polycrystalline ferrite, and the bond was clean. The effect of potassium hydroxide alcolade solution on bonded ferrite in preventing single crystallization and suppressing grain growth is remarkable.

Example 3 Mirror-polished Mn-Zn ferrite single-crystal ferrite (1) and polycrystalline ferrite (2) were mixed with cesium hydroxide (CsOH) dissolved in water at the interface.
I! .

A CsOH aqueous solution (3) was applied to temporarily adhere (see Fig. 1).

1 kg/cm for the sample after temporary adhesion! A bonded ferrite was produced by heat treatment at 1300"C for 2 hours in a N2 atmosphere while applying a pressure of The bonding state after heat treatment of this sample (4), in which a cesium hydroxide aqueous solution was applied to the interface between single crystal and polycrystalline ferrite, is shown in the photograph in Figure 5. Also, the bonding state after heat treatment of the comparative sample The bonded state is shown in the photograph in Fig. 6.

In the comparative sample in which the interface between single crystal and polycrystalline ferrite was temporarily bonded with water, it can be seen that the single crystallization and grain growth of the polycrystalline ferrite progresses.

In this sample (4) in which a cesium hydroxide aqueous solution was applied to the interface between single crystal and polycrystalline ferrite, single crystallization and abnormal grain growth of the polycrystalline ferrite were suppressed, and the bonding was clean. The effect of preventing single crystals and suppressing grain growth of a cesium hydroxide aqueous solution in bonded ferrite is remarkable.

Example 4 Mirror-polished Mn-Zn ferrite single crystal ferrite (1) and polycrystalline ferrite (2) were mixed with cesium hydroxide (CsOH) dissolved in ethanol at the interface.
CsOH alcoholade solution (3) of mol/l was applied to temporarily adhere (see Fig. 1). 1kg for the sample after temporary adhesion
/C111(7) Apply pressure, 13 in NZ atmosphere
Heat treatment was performed at 00°C for 2 hours to produce a bonded ferrite.

For comparison, a comparative sample in which water was applied to the interface of single-crystal ferrite and polycrystalline ferrite to temporarily bond the interface was heat-treated under the same conditions. The photograph in FIG. 7 shows the bonded state after heat treatment of this sample (4) in which a cesium hydroxide-alcolade solution was applied to the interface between single crystal and polycrystalline ferrite. The photograph of FIG. 8 shows the bonded state of the comparative sample after heat treatment.

In the comparative sample in which the interface between single crystal and polycrystalline ferrite was temporarily bonded with water, it can be seen that the single crystallization and grain growth of the polycrystalline ferrite progresses.

In this sample (4) in which the cesium hydroxide Alcolade solution was applied to the interface between single crystal and polycrystalline ferrite, single crystallization and abnormal grain growth of the polycrystalline ferrite were suppressed, and the bonding was clean. The effect of preventing single crystals and suppressing grain growth of cesium hydroxide Alcolade liquid in bonded ferrite is remarkable.

Example 5 Mirror-polished Mn-Zn ferrite single-crystal ferrite (1) and polycrystalline ferrite (2) were mixed with rubidium hydroxide (RbOH) dissolved in water at the interface.
1 of RbOH aqueous solution (3) was applied for temporary adhesion (see Figure 1). While applying a pressure of 1 kg/d to the sample after temporary bonding, a heat treatment was performed at 1300''C for 2 hours in a N2 atmosphere to produce a bonded ferrite. A comparative sample temporarily bonded by applying water to the interface was heat-treated under the same conditions. Figure 9 shows the bonding state after heat treatment of this sample (4), in which a rubidium hydroxide aqueous solution was applied to the interface of single crystal-polycrystal ferrite. The bonded state of the comparative sample after heat treatment is shown in the photograph of FIG.

In the comparative sample in which the interface between single crystal and polycrystalline ferrite was temporarily bonded with water, it can be seen that the single crystallization and grain growth of the polycrystalline ferrite progresses.

In this sample (4) in which a rubidium hydroxide aqueous solution was applied to the interface between single crystal and polycrystalline ferrite, single crystallization and abnormal grain growth of the polycrystalline ferrite were suppressed, and the bonding was clean. The effect of preventing a single crystal and suppressing grain growth of a rubidium hydroxide aqueous solution in bonded ferrite is remarkable.

Example 6 Mirror-polished Mn-Zn ferrite single-crystal ferrite (1) and polycrystalline ferrite (2) were mixed with rubidium hydroxide (RbOH) dissolved in ethanol at the interface.
, 5 mol/l of RbOH alcoholade solution (3) was applied for temporary adhesion (see Figure 1). 1 for the sample after temporary adhesion
13 kg/cm in a N2 atmosphere while applying a pressure of 11 m
Heat treatment was performed at 00°C for 22 hours to produce a bonded ferrite. For comparison, a comparative sample in which water was applied to the interface of single-crystal ferrite and polycrystalline ferrite to temporarily bond the interface was heat-treated under the same conditions. The photograph in FIG. 11 shows the bonded state after heat treatment of this sample (4), in which the rubidium hydroxide Alcolade solution was applied to the interface between single crystal and polycrystalline ferrite. The photograph of FIG. 12 shows the bonded state of the comparative sample after heat treatment.

In the comparative sample in which the interface between single crystal and polycrystalline ferrite was temporarily bonded with water, it can be seen that the single crystallization and grain growth of the polycrystalline ferrite progresses.

In this sample (4) in which the rubidium hydroxide Alcolade solution was applied to the interface between single crystal and polycrystalline ferrite, single crystallization and abnormal grain growth of the polycrystalline ferrite were suppressed, and the bonding was clean. The effect of rubidium hydroxide Alcolade liquid on bonded ferrite to prevent single crystals and suppress grain growth is remarkable.

In the present invention, when producing a bonded ferrite, a plurality of single crystal ferrites (1) and polycrystalline ferrites (2) are interposed at the interface with a solution (3) of KOH, Cs01 (, RbOH, etc.) as shown in the figure. It is also possible to fabricate multilayer bonded ferrite all at once by heat-pressing this laminated sample.

Methods for interposing solutions such as KOHCsOH and RbOH at the interface between single-crystal ferrite (1) and polycrystalline ferrite (2) include, for example, the usual coating method, and immersing both ferrites Q) and (2) in the above solution. Both ferrites (1
) and (2) may be impregnated with a solution at the interface.

The above-mentioned technique using solutions such as KOH, CsOH, and RbOH is applicable not only to the production of bonded ferrite, but also to the control of grain growth of so-called polycrystalline ferrite.

〔Effect of the invention〕

According to the method for manufacturing a bonded ferrite according to the present invention described above,
It has the following effects.

By interposing at least one type of hydroxide selected from Rb and Cs at the bonding interface between single-crystal ferrite and polycrystalline ferrite, the polycrystalline ferrite becomes single crystallized and grained during bonding (heat treatment). Growth is suppressed, and the bonding surface between single crystal and polycrystalline ferrite is clean with no occurrence of small holes or the like, and there is little occurrence of spot peeling. In particular, since polycrystalline ferrite is less likely to become a single crystal, there is less movement of the single-crystalline-polycrystalline ferrite interface, and therefore it is advantageous to fabricate a composite magnetic head using bonded ferrite.

Since it is possible to manufacture bonded ferrite in a normal atmosphere furnace without using a special furnace such as a hot press, productivity of bonded ferrite can be increased and costs can be reduced.

There is no need to apply a thin layer of iron oxide or the like to at least one of the interfaces between the single crystal and polycrystalline ferrite by sputtering or the like, and in this respect as well, productivity is high and costs can be reduced.

Since grain growth and single crystallization of polycrystalline ferrite are suppressed, the bonding temperature is set higher than the conventional temperature, that is, 1220'C-1.
The temperature can be raised up to 330''C. Therefore, the working temperature range is widened, the yield and productivity are improved, and the bonding strength is also improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a ferrite sample according to the present invention, and FIG. 2 is a photograph showing the bonded state (crystal structure) of the bonded ferrite after heat treatment of Example 1 (coated with KOH aqueous solution).
Figure 3 is a photograph showing the bonding state (crystal structure) of the bonded ferrite after heat treatment of the comparative example (H2O coated);
Figure 4 is a photograph showing the bonding state (crystal structure) of the bonded ferrite after heat treatment in Example 2 (coated with KOH Alcolade solution), and Figure 5 is a photograph showing the bonded state (crystal structure) of Example 3 (coated with CsOH aqueous solution) after heat treatment. Figure 6 is a photograph showing the bonding state (crystal structure) of the bonded ferrite after heat treatment of the comparative example (H2O coated), and Figure 7 is a photograph showing the bonding state (crystal structure) of the bonded ferrite. Example 4 (CsOH
Figure 8 shows the bonding state (crystal structure) of the bonded ferrite after heat treatment of the comparative example (coated with H2O). Figure 9 is a photograph showing the bonding state (crystal structure) of the bonded ferrite after heat treatment of Example 5 (coated with RbOH aqueous solution), and Figure 10 is a photograph showing its comparative example (coated with H2O). ) Photographs showing the bonding state (crystal structure) of bonded ferrite after heat treatment,
Figure 11 is a photograph showing the bonding state (crystal structure) of the bonded ferrite after heat treatment in Example 6 (RbOH Alcolade solution was applied), and Figure 12 is a photograph showing the heat treatment of the comparative example (H2O was applied). This is a photograph showing the bonding state (crystal structure) of bonded ferrite. (1) is single-crystal ferrite, (2) is polycrystalline ferrite, (3) is an aqueous solution (or alcoholado liquid) of KOH (or CsOH, or Rb01 ()), and (4) is this sample. 4 To the customer Gaito 2 crystal ferrite

Claims (1)

[Claims] In a method for manufacturing a bonded ferrite consisting of a single crystal ferrite and a polycrystalline ferrite, K and Rb are added at least to the bonding interface of the polycrystalline ferrite.
, Cs, and heat-press bonding in the presence of at least one hydroxide selected from Cs.