JP2000185940A - High-rigidity glass ceramic substrate for information magnetic memory medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart excellent surface smoothness, a high Young's modulus and a low specific gravity to a glass ceramic substrate by making the glass ceramic substrate have a specified ratio of its Young's modulus to its specific gravity and a specific Al2O3 content. SOLUTION: The high-rigidity glass ceramic substrate is prepared so that it may have the ratio of its Young's modulus (GPa)/its specific gravity of 37-63 and the content of Al2O3 of 10-20 wt.%. This base plate substantially does not include Na2O, K2O, Li2O, PfO and its main crystal phase comprises at least one selected from cordierite or cordierite solid solution, spinel crystals, solid solution of spinel crystal, enstatite, enstatite solid solution, β-quartz and β-quartz solid solution and the particle sizes of the crystals in individual crystal phases are adjusted to 0.05-0.30 μm. Further, this base plate has a thermal expansion coefficient of 30×10-7-50×10-7/ deg.C in the temperature range from -50-+70 deg.C and the surface roughness Ra after polishing of the substrate is 3-9 Å and the maximum surface roughness Rmax is <=100 Å.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for an information magnetic storage medium used for an information storage device, and more particularly, to a super-smooth substrate surface which is mainly used in a ramp load system and which is compatible with near contact recording or contact recording. A glass ceramic substrate for an information storage medium such as a magnetic disk substrate having a high Young's modulus and a low specific gravity capable of coping with high-speed rotation; a method of manufacturing the glass ceramic substrate for an information magnetic storage medium; The present invention relates to an information magnetic storage medium formed by performing a film forming process on a glass ceramic substrate for a storage medium.
In this specification, the term "information magnetic storage medium" refers to a fixed hard disk, a removable hard disk, a card hard disk, a data storage, a digital video camera, or a digital camera, which is used as a so-called hard disk of a personal computer. Means a usable disk-shaped information magnetic storage medium.

[0002]

2. Description of the Related Art In recent years, a magnetic information storage device of a removable type or a card type has been studied with respect to a conventional fixed type information magnetic storage device. is there. Due to such trends, the use of multimedia in personal computers and the spread of digital video cameras, digital cameras and the like have been rapidly advancing in recent years. In order to handle large-sized data such as moving images and voices, large-capacity information magnetic storage devices have been developed. Is required. To cope with this, information magnetic storage media must increase the bit and track densities and reduce the size of bit cells to increase the areal recording density, while the magnetic head must be mounted on the disk surface in accordance with the shrinking bit cells. It is moving toward the use of near-contact recording, which operates in closer proximity, and further employs a contact recording method.

Conventionally, an aluminum alloy has been widely used as a substrate material for a magnetic disk. In the case of an aluminum alloy substrate, projections or spot-like irregularities on the substrate surface in a polishing step are generated due to various material defects. In terms of flatness and smoothness, it is not sufficient as the substrate for the high-density magnetic storage medium, and since the aluminum alloy is a soft material, the Young's modulus and the surface hardness are low, so that the vibration is severe at high speed rotation of the drive. There is also a problem that deformation tends to occur and it is difficult to cope with thinning. In addition, it cannot sufficiently cope with today's high-density recording.

On the other hand, as a material for solving the problem of the aluminum alloy substrate, aluminosilicate glass of chemically strengthened glass is disclosed in JP-A-8-48537 and JP-A-5-32431.
(SiO ₂ —Al ₂ O ₃ —Na ₂ O) is known, but in this case, (1) polishing is performed after chemical strengthening, and the unstable element of the strengthening layer in thinning the disk is high. Further, the reinforced phase causes a change with time in long-term use, and deteriorates magnetic properties. (2) Na ₂ O, K ₂ O in glass
Since the component is contained as an essential component, the film-forming property is deteriorated, and a barrier coating treatment on the entire surface is required to prevent Na ₂ O and K ₂ O from being eluted. (3) Chemical strengthening is performed to improve the mechanical strength of the glass, but basically utilizes the strengthening stress of the surface phase and the internal phase, and the Young's modulus is equivalent to that of ordinary amorphous glass. The characteristics as a substrate for a high-density magnetic storage medium are still inadequate, for example, there is a limit of 83 GPa or less for use in a high-speed rotation drive.

Further, some crystallized glasses are known for aluminum alloy substrates and chemically strengthened glass substrates. For example, JP-A-9-35234, EP078
The glass-ceramic substrate for a magnetic disk disclosed in Japanese Patent No. 1731A1 has a Li ₂ O—SiO ₂ composition and a crystal phase in which lithium disilicate and β-spodumene or lithium disilicate and β-cristobalite are precipitated. However, they did not consider the relationship between the Young's modulus and the specific gravity for high-speed rotation at all, and did not give any suggestion.
The Young's modulus of this type of glass ceramics is 100 G
Pa is the limit.

[0006] In order to improve these low Young's modulus,
No. 9-77531 discloses SiO_Two-Al_TwoO_Three-MgO
-ZnO-TiO_TwoA system-crystallized glass is disclosed.
This crystallized glass has a large amount of spinel crystal with a large main crystal phase.
And MgTi as a sub-crystal_TwoO_FiveAnd several other crystals,
Crystallized glass having a Young's modulus of 93.4 to 160.11 GPa
And a rigid disk made of this crystallized glass for magnetic storage.
This material is a substrate that constitutes a mask.
(Mg / Zn) Al_TwoO_ThreeAnd / or (Mn / Zn)
_TwoTiO_FourSpinel crystal represented by
Other multiple crystals can be selected)_TwoO_ThreeContains a large amount of
As in the present invention described later, Al _TwoO_Threecomparison
Glass with both low Young's modulus and low specific gravity
It is different from ceramics. And like this
Al_TwoO_ThreeContains a large amount, the melting property of the raw glass decreased
Problems such as deterioration of devitrification resistance and
And the Young's modulus required for high-speed rotating drives
(GPa) / specific gravity and specific gravity value itself
Not considered at all and gave no suggestion for these
Not. In particular, the specific gravities are all higher than 2.87.
It has become something. Therefore, simply propose a hard material
It is just doing. Moreover, the crystallized glass of this system is hard
If the degree of processing is too high, the workability is poor and the mass production is inferior.
Substrate for high-density information magnetic storage media
The effect of the improvement is insufficient.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate for an information magnetic storage medium which can cope with the trend toward higher recording densities as described above in order to solve the above-mentioned drawbacks of the prior art. Magnetism that has excellent properties, devitrification resistance and workability, has excellent substrate surface smoothness for high recording density contact recording, and has high Young's modulus and low specific gravity characteristics for high-speed rotation drives. It is an object of the present invention to provide a glass ceramic substrate for a storage medium, a method for manufacturing the same, and an information magnetic storage medium in which a coating of a magnetic medium is formed on the glass ceramic substrate.

[0008]

The inventor of the present invention has conducted intensive tests and researches to achieve the above object. As a result, in order to cope with a high-speed drive, the information magnetic storage medium substrate is bent during high-speed rotation. The rigidity and the specific gravity of the substrate must be high to prevent the disk vibration due to the vibration. Therefore, the optimum ratio of the Young's modulus to the specific gravity of the substrate is: Young's modulus (GPa) / specific gravity = 37
~ 63, and arrived at the present invention. In order to achieve the above object, the present inventor has proposed that the main crystal phase is (1)
Limited to at least one selected from cordierite or cordierite solid solution and (2) spinel crystal, spinel crystal solid solution, enstatite, enstatite solid solution, β-quartz, β-quartz solid solution, and Each of the precipitated crystal particles has a fine spherical particle shape, and is excellent in the melting property, devitrification resistance and polishing workability of the raw glass, the surface after polishing is more excellent in smoothness, and a high speed corresponding to high speed rotation. The present inventors have found that a glass ceramic substrate for an information magnetic storage medium having both a Young's modulus and a low specific gravity can be obtained.

That is, the invention according to claim 1 is a high rigid glass ceramic substrate for an information magnetic storage medium,
Young's modulus (GPa) / specific gravity = range of 37 to 63 and A
characterized in that it is in the range of l less than _{2 O 3 = 10% ~20%} , which is information highly rigid glass-ceramic substrate for a magnetic storage medium, the invention of claim 2, Na ₂ O, K ₂ O ,
The high-rigidity glass-ceramic substrate for an information magnetic storage medium according to claim 1, wherein the glass-ceramics substrate is substantially free of Li ₂ O and PbO. Its main crystal phase is
(1) at least one selected from cordierite or cordierite solid solution and (2) spinel crystal, spinel crystal solid solution, enstatite, enstatite solid solution, β-quartz, β-quartz solid solution. The high-rigidity glass-ceramic substrate for an information magnetic storage medium according to claim 1 or 2, wherein the glass-ceramic substrate has a crystal grain size of each main crystal phase. Is 0.05 μm or more
The high-rigidity glass ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 3, wherein the glass ceramic substrate has a thickness of 0.30 µm. The coefficient of thermal expansion in the range of −50 to + 70 ° C. is 30 × 10 ⁻⁷ to 50 × 10 ⁻⁷ /
The high-rigidity glass-ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 4, characterized in that the temperature is within the range of ° C. Surface roughness Ra of the polished surface
The high-rigidity glass-ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 5, wherein (arithmetic average roughness) is 3 to 9 ° and surface maximum roughness Rmax is 100 ° or less. the invention of claim 7, wherein the weight percentage of the glass-ceramic substrate is an oxide _{basis, SiO 2 40 ~60% MgO 10} ~20% Al 2 O 3 less than _{10 ~20% P 2 O 5 0} ~ 4 _{% B 2 O 3 0 ~ 4} % CaO 0.5~ 4% BaO 0 ~ 5% ZrO 2 0 ~ 5% TiO 2 2.5~ 8% Sb 2 O 3 0 ~ 1% As 2 O 3 0 ~ 1 % F 0 obtained by heat-treating _{~ 3% SnO 2 0 ~ 5} % MoO 3 0 ~ 3% CeO 0 ~ 5% Fe 2 O 3 0 ~ 5% of the raw glass containing respective components of the range, the The main crystal phase of glass ceramic is (1)
(2) at least one selected from cordierite or cordierite solid solution and (2) spinel crystal, spinel crystal solid solution, enstatite, enstatite solid solution, β-quartz, β-quartz solid solution, The high-rigidity glass-ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 6, wherein the glass-ceramics are obtained by melting, molding and slowly cooling a glass raw material. The nucleation temperature is 650 ° C. to 750 ° C. and the crystallization temperature is 7
The method for producing a high-rigidity glass-ceramic substrate for an information magnetic storage medium according to claim 7, wherein the method is obtained by performing a heat treatment at 50 ° C to 1050 ° C. Item 10. An information magnetic storage medium disk comprising a high-rigidity glass ceramic substrate for an information magnetic storage medium according to any one of Items 1 to 8, on which a magnetic medium film is formed. In this specification, a spinel crystal is defined as (M
g and / or Zn) Al ₂ O ₄ , (Mg and / or Zn) ₂ TiO ₄ , or at least one selected from a mixture as a solid solution between the two crystals,
Further, a solid solution is a part of other components in each crystal,
Refers to what has been replaced and / or invaded.

The physical properties of the glass ceramic of the present invention,
The reasons for limiting the main crystal phase, crystal grain size, surface properties, and composition range as described above are described below. The composition is indicated on an oxide basis as in the original glass.

First, Young's modulus and specific gravity will be described. As described above, in order to improve the recording density and the data transfer speed, the trend of high-speed rotation of the information magnetic storage medium substrate is progressing.
It must have high rigidity and low specific gravity to prevent disk vibration due to deflection at high speed rotation of 10000 rev / min or more. Even if the rigidity is simply high, if the specific gravity is large, the weight is large at the time of high-speed rotation, causing deflection and vibration. Conversely, if the rigidity is small even at a low specific gravity, vibration is similarly generated. Therefore, while having high rigidity,
The seemingly contradictory properties of low specific gravity must be balanced, and the range is Young's modulus (GPa) / specific gravity = 37
６３63. A preferred range is Young's modulus (GPa) / specific gravity = 40 to 63, a more preferred range is Young's modulus (GPa) / specific gravity = 47 to 63, and a most preferred range is Young's modulus (GPa) / specific gravity = 50 to 63. 6
3. Note that there is a more preferable range for the rigidity, and even if the specific gravity is low, at least 120 GPa or more is preferable from the viewpoint of the vibration generation problem.
The following is preferred. The same applies to the specific gravity. From the viewpoint of the above-described vibration generation problem, even if the rigidity is not more than 3.50, the substrate tends to vibrate during high-speed rotation due to its own weight. If it is less than 3, it is substantially difficult to obtain a substrate having a desired rigidity. In consideration of this point, a preferable range of the specific gravity is 2.5 to 3.3.

Next, regarding the Na ₂ O, K ₂ O, Li ₂ O, and PbO components, the Na ₂ O, K ₂ O, and Li ₂ O components are included in the material in increasing the precision and miniaturization of the magnetic film. When these are contained, these ions diffuse into the magnetic film during the film forming process in which the substrate is heated to a high temperature (particularly remarkable in a barium ferrite perpendicular magnetization film having a high film forming temperature), and the magnetic film particles become coarse and have a large orientation. Therefore, it is important that these components are not substantially contained. Environmentally unfavorable P
The bO component should not be included.

Regarding the main crystal phase, first, in one aspect of the present invention, the main crystal phase is (1) cordierite or a cordierite solid solution and (2) spinel crystal, a solid solution of spinel crystal, enstatite, and enstatite. It is characterized by being at least one or more selected from a tight solid solution, β-quartz, and β-quartz solid solution.
This is because the above crystal phase has good workability, contributes to increase in rigidity, can make the precipitated crystal grain size relatively small, and realizes much lower specific gravity than other crystal phases. This is because there is an advantageous aspect that it can be performed. In each of the crystal phases, the precipitation and the ratio of each of the crystal phases of cordierite, spinel crystal, enstatite, and β-quartz were determined by Mg.
Depending on the content ratios of O, SiO ₂ and Al ₂ O ₃ , the precipitation of these four crystal phases and the solid solution phase of these four crystal phases and their ratios are determined by the content ratios of MgO, SiO ₂ , Al ₂ O ₃ and other components. Is determined by

Next, regarding the crystal grain size and the surface roughness, as described above, in order to support near-contact recording or contact recording for improving the recording density, the surface of the information magnetic storage medium is required. Must be better than conventional products. Even if an attempt is made to perform high-density input / output to / from a magnetic medium with the same level of smoothness, magnetic signals cannot be input / output due to the large distance between the head and the medium. Also, if the distance is reduced, the projection of the medium collides with the head, causing damage to the head and the medium. For these reasons, in order to cope with the near contact recording or the contact recording method, the smoothness of the disk substrate surface is determined by adjusting the surface roughness (Ra) = 3 to 9 ° and the maximum roughness (Rma).
x) = 100 ° or less. Preferably, the surface roughness (Ra) = 3 to 7 °, and the maximum roughness (Rma)
x) = 95 ° or less, more preferably surface roughness (Ra) = 3 to 6 ° and maximum roughness (Rmax) = 90 ° or less.

Next, regarding the grain morphology and grain size of these precipitated crystals, they have high rigidity and ultra-smoothness (3 to 9 mm in the data area) like the glass ceramic substrate as in the present application.
In order to obtain a glass-ceramic substrate having the following, crystal grains and shape are important factors. Desired strength and surface roughness cannot be obtained if the crystal grain size is larger or smaller than each of the above crystals.

Next, regarding the coefficient of thermal expansion, in increasing the bit and track densities and reducing the size of the bit cells, the difference in the coefficient of thermal expansion between the medium and the substrate has a great effect. Therefore, the coefficient of thermal expansion in the temperature range of −50 to + 70 ° C. is 30 × 10 ⁻⁷ to 50 × 10 ⁻⁷ /
It must be in ° C.

Next, the reasons for limiting the composition will be described. First S
The iO ₂ component is precipitated as cordierite, cordierite solid solution, enstatite, enstatite solid solution, β-quartz, β-
It is a very important component that produces quartz solid solution crystals,
If the amount is less than 40%, the precipitated crystal phase of the obtained glass ceramic is unstable and the structure becomes coarse.
If it exceeds 300, it becomes difficult to melt and form the raw glass. still,
The heat treatment conditions are also an important factor in precipitating these crystal phases, but wider heat treatment conditions can be used, and a more preferable range is 48.5 to 58.5%.

The MgO component is obtained by heat treatment of the raw glass.
It is a very important component that forms cordierite, cordierite solid solution, spinel crystal, solid solution of spinel crystal, enstatite, enstatite solid solution, β-quartz, β-quartz solid solution crystal precipitated as the main crystal phase. If the content is less than 10%, desired crystals cannot be obtained, and the obtained crystals of the glass ceramic are unstable, the structure is easily coarsened, and the meltability is further deteriorated. 20%
If it exceeds, the devitrification deteriorates. Note that, for the same reason as for SiO ₂ , a more preferable range is 13 to 20%.

The Al ₂ O ₃ component is formed of cordierite, cordierite solid solution, spinel crystal, spinel crystal solid solution,
Although it is a very important component for generating β-quartz solid solution crystals, if its amount is less than 10%, a desired crystal phase cannot be obtained, and the obtained crystal phase of glass ceramics is unstable and the structure is coarse. And the meltability deteriorates.
On the other hand, if it is 20% or more, the melting property and devitrification property of the raw glass are deteriorated, and the precipitation amount of spinel crystals is abnormally increased, so that the hardness is increased more than necessary, and the workability in polishing or the like is significantly reduced. The preferred range for the same reason as described above is less than 10 to 18%, and the particularly preferred range is 10 to 1%.
7%.

The P ₂ O ₅ component not only functions as a crystal nucleating agent for glass but also is effective for improving the melting and molding properties of the raw glass and improving the devitrification resistance, but within 4%. Is enough. Note that a preferable range is 1 to 3%.

The B ₂ O ₃ component is effective for controlling the viscosity of the raw glass at the time of melting and molding, but the amount is
Within 4% is sufficient.

The CaO component is a component that not only improves the meltability of the glass but also prevents the crystal phase from becoming coarse, but if the amount is less than 0.5%, the above effects cannot be obtained. %, The precipitated crystals become coarse, the crystal phase changes, and the chemical durability deteriorates. The preferred range is 1 to
3%.

The BaO component can be added to improve the melting property of the glass, but an amount of 5% is sufficient. still,
The preferred range is 1-3%.

The ZrO ₂ component and the TiO ₂ component not only function as a crystal nucleating agent for glass, but also have an effect on refining the precipitated crystal phase, improving the mechanical strength of the material, and improving the chemical durability. Is a very important component in which ZrO ₂ is less than 5%, and the above effect cannot be obtained if the content of TiO ₂ is less than 2.5%. Becomes difficult to melt, and the devitrification resistance deteriorates. Incidentally, by the same reason as the above SiO _2, and more preferably in the range of 2-8%.

The Sb ₂ O ₃ and As ₂ O ₃ components are used as fining agents when the glass is melted, but each content of 1% or less is sufficient.

The F component can be added to improve the melting property of the glass, but an amount within 3% is sufficient.

The SnO ₂ , MoO ₃ , CeO, and Fe ₂ O ₃ components are used to improve the sensitivity of detecting a surface defect by coloring or coloring glass and to improve the absorption characteristics of an LD-excited solid-state laser. To a total of 5%. The MoO ₃ component is preferably within 3%. Note that S
The nO ₂ and MoO ₃ components are translucent in a glass state before the heat treatment, but are important components that color after heat treatment crystallization.

In order to manufacture the glass-ceramic substrate for an information magnetic storage medium of the present invention, the glass having the above composition is melted, subjected to hot forming and / or cold working, and then heated to 650 ° C. to 750 ° C. Heat treatment at a temperature in the range of 1 to 12 hours to form crystal nuclei, followed by 750 ° C. to 1050 ° C.
The crystallization is performed by heat treatment at a temperature in the range of about 1 to 12 hours.

[0029]

Next, a preferred embodiment of the present invention will be described. Tables 1 to 7 show practical composition examples (Nos. 1 to 17) of the glass ceramic substrate for a magnetic disk of the present invention and a conventional chemically strengthened glass aluminosilicate glass (JP-A-8-48537) as a comparative composition example. Comparative example 1, Li ₂ O-SiO ₂ system glass-ceramics (Japanese Patent Laid-Open 9
Comparative Example 2, SiO ₂ —Al ₂ O ₃
-MgO-ZnO-TiO ₂ -based crystallized glass (Japanese Unexamined Patent Publication No.
The composition, nucleation temperature, crystallization temperature, crystal phase, crystal particle diameter, Young's modulus, specific gravity, Young's modulus (GPa) / specific gravity, surface roughness after polishing (Ra) ), Maximum surface roughness (Rmax), -50 to +7
The thermal expansion coefficient at 0 ° C. is shown.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

[0035]

[Table 6]

[0036]

[Table 7]

In each of the glasses of the above embodiments of the present invention, raw materials such as oxides, carbonates, nitrates and the like are mixed, and the mixture is melted at a temperature of about 1350 to 1490 ° C. using an ordinary melting apparatus, and the mixture is stirred and homogenized. Then, the mixture was molded into a disk and cooled to obtain a glass molded body. Thereafter, this is heat-treated at 650 to 750 ° C. for about 1 to 12 hours to form crystal nuclei.
Crystallization by heat treatment at 0 ° C. for about 1 to 12 hours gave the desired glass ceramic. Next, the above glass ceramic was wrapped with abrasive grains having an average particle diameter of 5 to 30 μm for about 10 to 60 minutes, and then polished with cerium oxide having an average particle diameter of 0.5 to 2 μm for about 30 to 60 minutes to finish.

As shown in Tables 1 to 7, the present invention and the conventional aluminosilicate chemically strengthened glass, Li ₂ O—Si
O ₂ system glass ceramics, SiO ₂ -Al ₂ O ₃ -MgO
The crystal phase of the glass ceramic is different from that of the comparative example of -ZnO-TiO ₂ -based glass ceramics, and the relationship between Young's modulus and specific gravity is higher than that of aluminosilicate chemically strengthened glass and Li ₂ O-SiO ₂ -based glass ceramics. Rigid or low specific gravity. Comparatively high rigidity and low specific gravity SiO ₂ —Al ₂ O ₃ —MgO—Zn in this comparative example
O-TiO ₂ glass ceramics are very hard materials, so that a desired value was not obtained in surface roughness. On the other hand, the glass ceramics of the present invention are excellent in workability, sufficiently obtain the desired smoothness, and in addition, have a fine, homogeneous and fine structure without defects such as crystal anisotropy, foreign matter, impurities, etc. It had chemical durability enough to withstand cleaning with various chemicals and water or etching.

[0039]

As described above, according to the present invention, while eliminating the above-mentioned drawbacks of the prior art, it is possible to obtain a high recording density contact recording with excellent meltability, devitrification resistance and workability. High rigidity glass ceramic substrate for information magnetic storage media, which has both high Young's modulus and low specific gravity characteristics compatible with high-speed rotation drive while having excellent substrate surface smoothness corresponding to An information magnetic storage medium formed by forming a coating of a magnetic medium can be provided.

[Procedure amendment]

[Submission date] October 13, 1999 (1999.10.
13)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

That is, the invention according to claim 1 provides information
In a high rigid glass ceramic substrate for a magnetic storage medium,
Young's modulus (GPa) / specific gravity = range of 37 to 63 and A
l_TwoO_Three= 10weight% To 20weight%
High-rigidity glass ceramic for information magnetic storage media, characterized by
Substrate, and the invention according to claim 2 comprises Na
_TwoO, K_TwoO, Li_TwoSubstantially free of O and PbO
2. The height for an information magnetic storage medium according to claim 1, wherein:
4. A rigid glass-ceramic substrate, according to claim 3,
The invention relates to the glass ceramic substrate,
The crystal phase is (1) cordierite or cordierite
Solid solution and (2) spinel crystal, solid solution of spinel crystal
Body, enstatite, enstatite solid solution, β-stone
At least one member selected from the group consisting of English and β-quartz solid solutions
3. The method as claimed in claim 1, wherein
High-rigidity glass ceramic for magnetic information storage media
The invention according to claim 4 is a glass substrate.
In the case of the lamic substrate, the crystal grain size of each main crystal phase is 0.1 mm.
Characterized in that the thickness is from 0.05 μm to 0.30 μm.
Item 4. High rigidity for an information magnetic storage medium according to any one of Items 1 to 3.
The invention according to claim 5, which is a glass ceramic substrate.
Represents -50 to +7 in the glass ceramic substrate.
The coefficient of thermal expansion in the range of 0 ° C. is 30 × 10^-7~ 50
× 10^-7/ ° C range.
High rigidity glass for an information magnetic storage medium according to any one of claims 1 to 4,
The invention according to claim 6 is a ceramic substrate,
In the glass ceramic substrate, the surface of the polished surface
Surface roughness Ra (arithmetic average roughness) 3 to 9 mm, maximum surface roughness
Rmax is less than 100 °
Item 6. High rigidity for an information magnetic storage medium according to any one of Items 1 to 5
The invention according to claim 7, which is a glass ceramic substrate.
Means that the glass ceramic substrate has a weight percentage based on oxides.
At the rate, SiO_Two 40-60% MgO10-20% Al_TwoO_Three 10 to less than 20% P_TwoO_Five 0 to 4% B_TwoO_Three 0-4% CaO 0.5-4% BaO 0-5% ZrO_Two 0-5% TiO_Two 2.5-8% Sb_TwoO_Three 0 to 1% As_TwoO_Three 0 to 1% F0 to 3% SnO_Two 0 to 5% MoO_Three 0 to 3% CeO 0 to 5% Fe_TwoO_Three Heat-treating the raw glass containing each component in the range of 0 to 5%.
And the main crystal phase of the glass ceramic is (1)
Cordierite or cordierite solid solution and
(2) Spinel crystal, solid solution of spinel crystal, Enstar
Tight, enstatite solid solution, β-quartz, β-quartz solid
At least one selected from the solution
The information magnet according to any one of claims 1 to 6, characterized in that:
High rigid glass ceramic substrate for storage media.
Item 8. The invention according to Item 8, wherein the glass ceramic is glass
After melting, molding and slow cooling the raw material,
The nucleation temperature is 650 ° C. to 750 ° C. and the crystallization temperature is 7
Obtained by heat treatment at 50 ° C to 1050 ° C
The height for an information magnetic storage medium according to claim 7, characterized in that:
A method for manufacturing a rigid glass-ceramic substrate, the method comprising:
The invention according to claim 9 provides the information according to any one of claims 1 to 8.
The magnetic field on high rigid glass ceramic substrate for magnetic storage media
Information magnetic storage media disk with a gaseous medium coating formed
is there. In this specification, a spinel crystal is defined as (M
g and / or Zn) Al_TwoO_Four, (Mg and / or
Is Zn)_TwoTiO_FourAs a solid solution between the two crystals
It refers to at least one or more selected from among the things,
Further, a solid solution is a part of other components in each of the crystals,
Refers to what has been replaced and / or invaded.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C03C 3/097 C03C 3/097 3/112 3/112 3/118 3/118 10/06 10/06 10 / 08 10/08 G11B 5/73 G11B 5/704 (72) Inventor Junko Ishioka 1-15-30 Koyama, Sagamihara-shi, Kanagawa F-term in Ohara Co., Ltd. 4G062 AA11 AA18 CC01 CC09 DA05 DA06 DB04 DC01 DC02 DC03 DD01 DD02 DD03 DE01 DF01 EA01 EB01 EC01 ED04 EE02 EE03 EF01 EG01 EG02 EG03 FA01 FB03 FC01 FC02 FC03 FD01 FE01 FE02 FE03 FF01 FG01 FH01 FJ01 FK01 FL01 FL02 FL03 GA01 GA03 GE01 H01 GE01 H01 GE01 H HH13 HH15 HH17 HH20 JJ01 JJ03 JJ04 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM27 NN33 NN40 PP05 QQ02 QQ06 QQ08 5D006 CB04 CB07 DA03 FA09

Claims (9)

[Claims] 1. A high rigid glass ceramic substrate for an information magnetic storage medium, wherein Young's modulus (GPa) / specific gravity = 37 to
63. A high-rigidity glass-ceramic substrate for an information magnetic storage medium, wherein the range is 63 and Al ₂ O ₃ is in a range of 10% to less than 20%. 2. The high-rigidity glass-ceramic substrate for an information magnetic storage medium according to claim 1, wherein the substrate is substantially free of Na ₂ O, K ₂ O, Li ₂ O, and PbO. 3. The glass ceramic substrate,
The main crystal phases are (1) cordierite or cordierite solid solution and (2) spinel crystal, spinel crystal solid solution, enstatite, enstatite solid solution, β
At least one selected from the group consisting of quartz and β-quartz solid solution;
The high-rigidity glass ceramic substrate for an information magnetic storage medium according to claim 1, wherein the substrate is at least one kind. 4. The information magnetic storage medium according to claim 1, wherein in the glass ceramic substrate, a crystal grain size of each main crystal phase is 0.05 μm to 0.30 μm. High rigid glass ceramic substrate. 5. The method according to claim 1, wherein:
The coefficient of thermal expansion in the range of 50 to + 70 ° C. is 30 × 1
The high-rigidity glass-ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 4, wherein the temperature is in the range of ^0-7 to 50 x ^10-7 / C. 6. A surface roughness Ra (arithmetic mean roughness) of the polished surface of the glass ceramic substrate is 3 to 9.
The high-rigidity glass ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 5, wherein the maximum surface roughness Rmax is 100% or less. 7. A percentage by weight of the glass-ceramic substrate is an oxide _{basis, SiO 2 40 ~60% MgO 10} ~20% Al 2 O 3 less than _{10 ~20% P 2 O 5 0} ~ 4% B 2 O 3 0 to 4% CaO 0.5 to 4% BaO 0 to 5% ZrO ₂ 0 to 5% TiO ₂ 2.5 to 8% Sb ₂ O ₃ 0 to 1% As ₂ O ₃ 0 to 1% F 0 to 3 % SnO ₂ 0 to 5% MoO ₃ 0 to 3% CeO 0 to 5% Fe ₂ O ₃ 0 to 5% is obtained by heat-treating an original glass containing each component, and the main crystal of the glass ceramic is obtained. The phases are (1)
(2) at least one selected from cordierite or cordierite solid solution and (2) spinel crystal, spinel crystal solid solution, enstatite, enstatite solid solution, β-quartz, β-quartz solid solution, A high-rigidity glass-ceramic substrate for an information magnetic storage medium according to claim 1. 8. The glass ceramic is prepared by melting, molding and gradually cooling a glass raw material, and then, as crystallization heat treatment conditions, a nucleation temperature of 650 ° C. to 750 ° C. and a crystallization temperature of 750 ° C.
The method for producing a highly rigid glass-ceramic substrate for an information magnetic storage medium according to claim 7, wherein the method is obtained by performing a heat treatment at a temperature of from 1050C to 1050C. 9. An information magnetic storage medium disk comprising a high-rigidity glass ceramic substrate for an information magnetic storage medium according to claim 1 and a magnetic medium film formed thereon.