JP2008031001A - Lead-free glass composition and magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable lead-free glass composition with a low melting point and a magnetic head using the lead-free glass composition. <P>SOLUTION: The lead-free glass composition in one embodiment comprises, by mass, 60-69% Bi<SB>2</SB>O<SB>3</SB>, 10-20% B<SB>2</SB>O<SB>3</SB>, 5-7% ZnO, 2-8% SiO<SB>2</SB>, 1-5% Na<SB>2</SB>O, >1 and ≤3% Sb<SB>2</SB>O<SB>3</SB>, 0.5-8% Al<SB>2</SB>O<SB>3</SB>, 0-5% Fe<SB>2</SB>O<SB>3</SB>, 0-1% Li<SB>2</SB>O and 0-4% ZrO<SB>2</SB>expressed in terms of oxide and does not contain a lead-based compound such as PbO. The lead-free glass composition in another embodiment comprises, by mass, 60-69% Bi<SB>2</SB>O<SB>3</SB>, 10-20% B<SB>2</SB>O<SB>3</SB>, 5-7% ZnO, 2-8% SiO<SB>2</SB>, 1-5% Na<SB>2</SB>O, >1 and ≤3% Sb<SB>2</SB>O<SB>3</SB>and 0.5-2% AlF<SB>3</SB>expressed in terms of oxide and does not contain a lead-based compound such as PbO. The magnetic head is formed using these lead-free glass compositions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a lead-free glass composition. More specifically, the present invention relates to a bonding glass for a magnetic head used for fusing ferrite or metal, for example, a bonding glass suitable for gap formation and bonding of a magnetic head.
Furthermore, the present invention relates to a magnetic head using the above lead-free glass.

  In general, a magnetic head is formed by bonding and integrating magnetic cores made of an oxide magnetic material such as Mn-Zn ferrite or a composite of the oxide magnetic material and a metal magnetic material such as Sendust using bonding glass. Composed. For example, the working gap part of a magnetic head can be obtained by heating and melting a bonding glass drawn in a rod shape to a working high temperature above the melting point, pouring it between magnetic cores, and then cooling the glass between these magnetic cores. It is configured by fusing.

Such bonding glass is required to have severe characteristics in terms of water resistance, corrosion resistance, wear resistance, bonding strength, and the like, and since it can be drawn in a rod shape, a bonding glass mainly composed of PbO, SiO ₂ or the like has been proposed. (For example, refer to Patent Document 1).

By the way, if the thermal expansion coefficient of the magnetic head bonding glass is greatly different from that of an oxide magnetic material or a metal magnetic material, the residual stress is accumulated when the magnetic core is bonded, and thus there is a disadvantage that glass cracks are likely to occur. ing.
Therefore, the bonding glass for bonding an oxide magnetic material such as ferrite or a metal magnetic material has a thermal expansion coefficient of 85 × 10 ^{−7 to} 120 × 10 ⁻⁷ [ It is preferable to use a thing of about [° C. ⁻¹ ] Moreover, since the high temperature at the time of fusion will affect the magnetic properties of ferrite and metal magnetic thin film, the fusion temperature is preferably 600 ° C. or lower (450 ° C. or lower at the glass transition point).

However, low-melting glass has a problem that chemical durability such as water resistance and alkali resistance is remarkably inferior to that of high-melting glass, and glass elution with a grinding liquid or a cleaning liquid frequently occurs when processing a magnetic head.
Also, conventional fused glass contains lead oxide PbO in order to lower the melting point, but since lead is an environmental management substance, it has environmental problems and disposal problems, and contains lead-based components. There is a need for low melting glass.

On the other hand, in order to achieve high-density recording, not only magnetic powder coating type but also vapor deposition type has come out and various types of tape sliding lubricants are used accordingly. Of these, lubricants with high abrasiveness are also used. When such a magnetic tape slides on the magnetic head, there is a problem in that the glass exposed on the sliding portion of the magnetic head is unnecessarily polished to cause a step in the sliding portion of the magnetic head. There is a need for glasses with excellent wear properties.
JP 61-101432 A

By the way, the conditions and problems specifically required for the lead-free glass used in the magnetic head are as follows.
(1) It is necessary to make the fusion temperature 600 ° C. or lower (450 ° C. or lower at the glass transition point) without containing lead-based components.
(2) The coefficient of thermal expansion is about 85 × 10 ^{−7 to} 120 × 10 ⁻⁷ [° C. ⁻¹ ].
(3) Good chemical durability is required.
(4) In general, lead-free glass tends to have a higher fusing temperature than lead-based component-containing glass. Therefore, in order to achieve low melting as in (1), B ₂ O ₃ is used as a glass-forming component rather than SiO _2. In many cases, lead-free low-melting glass is significantly inferior in wear resistance to low-melting glass containing lead-based components.
(5) Accordingly, a lead-free low-melting glass having a significantly improved wear resistance while suppressing the fusing temperature to 600 ° C. or lower (glass transition point 450 ° C. or lower) is required. In a magnetic head using a lead-free glass composition on the sliding surface, it is necessary to make the magnetic head have good electromagnetic conversion characteristics with little uneven wear on the sliding portion of any magnetic tape.

An object of the present invention is to provide a lead-free glass composition that satisfies the characteristics required for a glass for a magnetic head and has no problems in the working environment and disposal.
Another object of the present invention is to provide a magnetic head using such lead-free glass.

In order to achieve the above-mentioned problems, the present inventors have developed oxides such as Bi ₂ O ₃ , B ₂ O ₃ , and ZnO that have no problem in the work environment and waste disposal, and aluminum such as Al ₂ O ₃ and AlF _3. Paying attention to the system components, the present inventors have found a stable glass composition having the characteristics of being contained in a lead-based glass without containing a lead-based component.

That is, the lead-free glass composition according to the present invention is expressed in terms of mass% based on oxide, Bi ₂ O ₃ : 60 to 69%, B ₂ O ₃ : 10 to 20%, ZnO: 5 to 7%, SiO ₂ : _{2~8%, Na 2 O: 1~5} %, Sb 2 O 3: 1 3% greater than or _{less, Al 2 O 3: 0.5~8%} , Fe 2 O 3: 0~5%, Li2O: It consists of 0 to 1%, ZrO ₂ : 0 to 4%, and does not contain lead-based components such as PbO.

Moreover, the lead-free glass composition according to the present invention is expressed in terms of mass% based on oxide, Bi ₂ O ₃ : 60 to 69%, B ₂ O ₃ : 10 to 20%, ZnO: 5 to 7%, SiO ₂ : It consists of 2 to 8%, Na ₂ O: 1 to 5%, Sb ₂ O ₃ : 1 and more than 3%, AlF ₃ : 0.5 to 2%, and does not contain lead-based components such as PbO And

  A magnetic head according to the present invention is characterized by using the above lead-free glass composition.

Bi ₂ O ₃ is a main component of the lead-free glass composition and has an effect of lowering the softening point and viscosity. This content is 60 to 69% (hereinafter, “%” means “% by mass” unless otherwise specified). When the content of Bi ₂ O ₃ exceeds 69%, chemical durability such as water resistance and alkali resistance of glass and abrasion resistance are remarkably deteriorated. It can no longer be used on the sliding surface of a magnetic head that slides on a vapor-deposited tape using a lubricant, and this glass always contains SiO ₂ and an aluminum-based component that raise the fusing temperature. If the content of Bi ₂ O _{3 having} the effect of lowering the deposition temperature is less than 60%, the fusion temperature becomes higher than the applicable range and the wettability is deteriorated. A more preferable content of Bi ₂ O ₃ is in the range of 64 to 69%.

B ₂ O ₃ has an effect as a glass forming component, and its content is 10 to 20%. Since this glass necessarily contains SiO ₂ and an aluminum component that raise the fusing temperature, if the content of B ₂ O ₃ exceeds 20%, the fusing temperature becomes higher than the applicable range, and if it is less than 10%, the glass It becomes unstable and easy to devitrify. A more preferable content of B ₂ O ₃ is in the range of 12 to 14%.

ZnO is a main component of lead-free glass and is effective in stabilizing the glass. This content is 5-7%. When there is more B ₂ O ₃ than SiO ₂ as a glass-forming component as in the present invention, if the ZnO content exceeds 7%, the wear resistance of the glass deteriorates, and this glass is made highly magnetic. If it is less than 5%, the glass becomes unstable and tends to devitrify.

SiO ₂ forms a network structure of glass, and is effective in stabilizing the glass, expanding the vitrification range, increasing the melting point, and improving the chemical durability and wear resistance. This content is 2-8%. Since the present glass always contains an aluminum-based component that raises the fusing temperature, if the SiO ₂ content exceeds 8%, the fusing temperature becomes higher than the applicable range, and the thermal expansion coefficient becomes smaller than the applicable range. On the other hand, if the SiO ₂ content is less than 2%, the wear resistance of the glass deteriorates, and this glass cannot be used on a sliding surface of a magnetic head that slides on a magnetic tape having high polishing properties. A more preferable content of SiO ₂ is in the range of 6 to 8%.

Na ₂ O has an effect of promoting the melting of the glass and lowers the fusing temperature. However, when contained in a large amount, the reliability of the glass is lowered and the thermal expansion becomes larger than the applicable range. Therefore, this content was 1 to 5%. If the content of Na ₂ O exceeds 5%, the wear resistance of the glass is greatly reduced, and it becomes difficult to use it on the sliding surface of a magnetic head that slides on a magnetic tape having high abrasiveness. If it is less than%, the fusing temperature becomes high and the wettability is deteriorated, and the thermal expansion coefficient is also smaller than 85 × 10 ⁻⁷ [° C. ⁻¹ ]. From the viewpoints of wear resistance, water resistance, alkali resistance and thermal expansion, a more preferable content of Na ₂ O is in the range of 1 to 3%.

By substituting Sb ₂ O _{3 with} a part of Bi ₂ O ₃ , there is an effect of improving water resistance and alkali resistance without relatively increasing the glass fusing temperature. This content is more than 1% and not more than 3%. If the content of Sb ₂ O ₃ exceeds 3%, the glass becomes unstable, and precipitates are likely to be generated in the glass at the time of fusing, so that the wetness of the glass is deteriorated or cracks are generated in the precipitation part. In addition, if it is 1% or less, the effect of improving water resistance and alkali resistance cannot be sufficiently exhibited. The more preferable content of Sb ₂ O ₃ is in the range of more than 1 and 2% or less.

Al ₂ O ₃ has an effect of improving wear resistance. This content is 0.5-8%. If the content of Al ₂ O ₃ exceeds 8%, the glass becomes unstable and cannot be drawn, or the glass becomes poorly wet. If it is less than 0.5%, the effect of improving the wear resistance does not appear. Further, the increase in Al ₂ O ₃ improves the wear resistance as described above, but the chemical durability such as water resistance and alkali resistance is easily deteriorated. Therefore, the more preferable content of Al ₂ O ₃ is 0.5. It is in the range of ˜4%.

AlF ₃ has the effect of improving the wear resistance in the same manner as Al ₂ O ₃ , but AlF ₃ has an advantage that the melting point decreases as the amount increases, and wettability does not deteriorate as compared with Al ₂ O ₃ . However, the range of AlF ₃ content is narrow, 0.5-2%. When the content of Al ₂ O ₃ exceeds 2%, the glass becomes unstable and cannot be drawn, or precipitates are generated in the fused glass and the wetting is deteriorated. If it is less than 0.5%, the effect of improving the wear resistance does not appear.

Fe ₂ O ₃ has the effect of improving the chemical durability such as water resistance and alkali resistance without relatively increasing the glass fusing temperature, and has a small amount of chemical durability deteriorated by the addition of Al ₂ O _3. Can be restored by adding Fe ₂ O _{3 and} there is an effect of slightly improving the wear resistance. The content of Fe ₂ O ₃ is 0 to 5%. However, since the vitrification range is limited by the addition of Al ₂ O ₃ , if the content of Fe ₂ O ₃ exceeds 5%, the glass becomes unstable and cannot be drawn. The more preferable content of Fe ₂ O ₃ is in the range of 0 to 3%. Moreover, since it is not compatible with glass containing AlF ₃ and is difficult to vitrify, it is better not to use Fe ₂ O _{3 for} glass containing AlF ₃ .

Li ₂ O has the effect of lowering the fusing temperature and improving the wettability of the glass, but if contained in a large amount, the reliability of the glass is lowered and the thermal expansion is increased. The wettability of the glass deteriorated by the addition of Al ₂ O ₃ can be restored by adding a small amount of Li ₂ O, and the content is 0 to 1%. If the content of Li ₂ O exceeds 1%, the water resistance of the glass is greatly lowered, and the glass becomes unstable and cannot be drawn. Furthermore, since it does not seem to be compatible with the glass containing AlF ₃ and is difficult to vitrify, it is better not to use Li ₂ O for the glass containing AlF ₃ .

ZrO ₂ has the effect of improving the chemical durability such as water resistance and alkali resistance, and the chemical durability deteriorated by the addition of Al ₂ O ₃ can be restored by the addition of a small amount of ZrO _2. There is also an effect of greatly improving the sex. This content is 0-4%. When the content of ZrO ₂ exceeds 4%, the glass fusing temperature rises and wettability deteriorates, and precipitates are easily generated in the glass during fusing. The more preferable content of ZrO ₂ is in the range of 0 to 2%. Furthermore, since it is not compatible with glass containing AlF ₃ and is difficult to vitrify, it is better not to use ZrO ₂ for glass containing AlF ₃ .

Further, as shown in a reference example described later, TiO ₂ , NiO, MgO, CaF ₂ , and CaO are components that have an effect of improving wear resistance in the same manner as Al ₂ O ₃ .

  Since the lead-free glass composition according to the present invention does not contain a lead-based component, the lead-free glass composition has an effect of improving the working environment and is not troublesome for disposal.

In addition, since the lead-free glass composition according to the present invention always contains SiO ₂ and an aluminum-based component, the wear resistance is greatly improved as compared with the conventional lead-free glass, and fusion is performed while ensuring chemical durability. The temperature is suppressed to 600 ° C. or lower. Therefore, the lead-free glass composition of the present invention can be used for a sliding surface of a magnetic head that slides on a magnetic tape having high polishing properties, and is suitable for application to a gap and joining of a magnetic head.

  According to the magnetic head of the present invention, since the lead-free glass composition of the present invention is used for a sliding surface or the like, the sliding part has little uneven wear on any magnetic tape, and good electromagnetic A magnetic head having conversion characteristics can be provided.

  Embodiments of the present invention will be described below.

  First, the lead-free glass composition according to the present embodiment will be described. Each component which comprises lead-free glass was mixed in the ratio shown in the Example of Table 1, and lead-free glass was created. The unit is mass%. In addition, what was put on the comparative example is the lead-free glass of the lead-free glass of the composition outside the claim, and the present use. Moreover, what was put on the reference example is the glass which has abrasion resistance according to an Example by addition of components other than the aluminum type.

  About each glass obtained by the composition of Table 1, the thermal expansion coefficient (100-350 degreeC) and the glass transition point were measured. The results are shown in Table 2.

Of the glasses obtained from the compositions in Table 1, each of the samples 1 to 14 of the example and each of the samples 15 to 19 of the reference example were vitrified, and neither crystallization nor devitrification was observed. Further, each sample 1 to 14 of Examples as shown in Table 2 (at 100 to 350 ° C.) thermal expansion coefficient of each sample 15 to 19 of the reference ^{example, 86 × 10- 7 ~98 × 10-} 7 [/ ° C.], glass transition point was 415 to 445 ° C.

  In Table 3, the result of having evaluated the abrasion resistance of the glass of each sample 1-24 in an Example, a reference example, and a comparative example is shown.

  1 and 2 are graphs of Table 3. FIG. In addition, the code | symbol in FIG.1 and FIG.2 is a sample number. The test method uses an open reel long-distance friction measuring device, and as shown in FIG. 3, the magnetic tape 2 on the side of the fixed drum 1 slides in a rod shape in a direction perpendicular to the tape running direction. The glass 3 is attached with resin, and the magnetic tape 2 brought into contact with the glass 3 with a constant tension is slid by a predetermined distance. The side surface of the glass 3 at that time is shown in FIG. 4. A part of the glass 3 is scraped with the tape 2, and the shaved portion is defined as a dense shaded area A. The scraped width 2Y was measured, and the scraped volume was calculated from the wire diameter 2R of the glass 3, the scraped width 2Y and the scraped length (depth). However, since the length (depth) of the cut glass 3 is the tape width, it is constant, and there is no problem even if it is not included in the calculation for the comparison of the cut dimensions, so calculate the area instead of the volume. Compared. Samples were measured one by one with a glass 3 drawn to an outer diameter of 0.5 ± 0.02 mm, epoxy resin was used for bonding the glass 3, and the sliding surface of the glass 3 with the magnetic tape 2 was Resin was prevented from adhering. The environment is set to 40 ° C. and 30% in a thermostatic chamber, and the tape 2 uses a 1/4 inch wide vapor deposition tape (using solid lubricant) for digital video, and a new tape is used each time the glass 3 is changed. One way 140m was reciprocated 10 times. The tape speed at this time is 5 m / sec, and the drum 1 does not rotate.

  The shaved area was determined as follows. As shown in FIG. 4 (cross section of the rod-shaped glass 3), the cut width is 2Y, the cut cross-sectional area is the dense shaded area A, and the sector area including the dense shaded area A and the coarse shaded area B From this, the area of the triangle (coarse shaded area B) was determined and used as the scraped area A.

  As is apparent from the evaluation in Table 3 and FIGS. 1 and 2, the lead-free glass compositions of the samples 1 to 14 of the examples show higher wear resistance than the samples 20 to 23 of the comparative examples. Yes. Moreover, although the samples 15-19 of a reference example are not as high as an Example, they show high abrasion resistance compared with the samples 20-23 of a comparative example.

Since the comparative sample 20 and sample 21 have a Bi ₂ O ₃ content exceeding 69%, the abrasion resistance and chemical durability of the glass deteriorate significantly, and the glass slides with a magnetic tape having a high polishing property. Cannot be used for the sliding surface of a magnetic head.
The sample 22 of the comparative example has more B ₂ O ₃ than SiO ₂ as a glass forming component, and ZnO exceeds 7%, so that the wear resistance is remarkably deteriorated. The glass is slid with a magnetic tape having a high polishing property. Such a magnetic head cannot be used as a sliding surface.
Since the sample 23 of the comparative example contains more B ₂ O ₃ than SiO ₂ as a glass forming component and contains BaO, the wear resistance is remarkably deteriorated, so that the glass slides with a magnetic tape having high abrasiveness. Cannot be used for the sliding surface of a magnetic head.
The sample 24 of the comparative example is a lead-based component-containing glass mainly composed of conventional PbO.

  It has been found that the glass having the composition range of claims 1 and 2 has the same thermal expansion coefficient, working temperature, and chemical durability as the lead glass, and the wear resistance has the same characteristics as the lead glass. Therefore, for example, a magnetic head as shown in FIG. 5 was produced using the glass of the sample 8 of the example and evaluated.

  The magnetic head 11 according to this embodiment is a so-called metal-in-gap (MIG) type magnetic head, and a high magnetic permeability metal magnetic thin film 13 is formed on the abutting surfaces of the ferrite core halves 12L and 12R. Both ferrite core halves 12L and 12R are joined with a lead-free glass composition (sample 8) 14 so that a magnetic gap g is formed between the metal magnetic thin films 13 via a gap film. Reference numeral 16 denotes a coil wound around the ferrite core half.

  The magnetic head 11 of the present embodiment thus obtained can fuse the glass 14 under the same fusing conditions as the conventional lead-based glass (Comparative Example Sample 24), and does not cause a glass crack. The head can be completed. Even if the glass 14 is exposed on the sliding surface as shown in FIG. 5, the chemical durability is equivalent to that of the conventional lead-based glass, and the wear resistance is as good as that of the lead-based glass.

  Although the embodiments of the present invention have been described above, the lead-free glass composition and the magnetic head according to the present invention are not limited to the above-described embodiments. For example, as a magnetic head constituted by using the lead-free glass composition according to the present invention, a MIG type magnetic head has been described as an example. However, it can be applied to other types of magnetic heads such as a metal thin film laminated type head. it can.

  Also, for example, in the MIG type magnetic head configured using the lead-free glass composition according to the present invention, the lead-free glass composition according to the present invention is used as a fused glass provided on the so-called front gap side exposed on the sliding surface, The lead-free glass composition and the magnetic head according to the present invention can be variously modified and modified, such as a configuration using a glass composition having another composition on the so-called back gap side separated from the sliding surface. .

It is the graph which showed the abrasion resistance evaluation result of a part of Example of Table 3, and the comparative example in the graph, and shows the relationship between the shaved area and the amount of component addition. It is the graph which shows the abrasion resistance evaluation result of each sample of Table 3, and shows the relationship between the shaved area and the glass transition point. It is a block diagram which shows the measuring method of abrasion resistance. It is explanatory drawing with which it uses for calculation of the area of the cut glass. 1 is a configuration diagram showing an embodiment of a magnetic head according to the present invention.

Explanation of symbols

  11 .. Magnetic head, 12L, 12R ... Ferrite core half, 13. Metallic magnetic thin film, 14. Lead-free glass, g ... Magnetic gap

Claims (6)

Bi ₂ O ₃ : 60-69%, B ₂ O ₃ : 10-20%, ZnO: 5-7%, SiO ₂ : 2-8%, Na ₂ O: 1-5 %, Sb ₂ O ₃ : 1 and exceeding 3%, Al ₂ O ₃ : 0.5 to 8%, Fe ₂ O ₃ : 0 to 5%, Li ₂ O: 0 to 1%, ZrO ₂ : 0 A lead-free glass composition comprising 4%. Bi ₂ O ₃ : 64-69%, B ₂ O ₃ : 12-14%, ZnO: 5-7%, SiO ₂ : 6-8%, Na ₂ O: 1-3 %, Sb ₂ O ₃ : 1 and over 2%, Al ₂ O ₃ : 0.5 to 4%, Fe ₂ O ₃ : 0 to 3%, Li ₂ O: 0 to 1%, ZrO ₂ : 0 A lead-free glass composition comprising 2%. Bi ₂ O ₃ : 60-69%, B ₂ O ₃ : 10-20%, ZnO: 5-7%, SiO ₂ : 2-8%, Na ₂ O: 1-5 _%, Sb _{2 O} 3: 1 3% greater than or _less, AlF 3: lead-free glass composition characterized in that it consists of 0.5% to 2%. Bi ₂ O ₃ : 64-69%, B ₂ O ₃ : 12-14%, ZnO: 5-7%, SiO ₂ : 6-8%, Na ₂ O: 1-3 %, Sb ₂ O ₃ : more than 1% and 2% or less, AlF ₃ : 0.5 to 2%. A magnetic head comprising the lead-free glass composition according to claim 1, 2, 3, or 4. The magnetic head according to claim 5, wherein at least a part of the lead-free glass composition is exposed on a sliding surface facing the recording medium.

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