JP2001148114A - Glass ceramic substrate for information magnetic storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for an information magnetic storing medium, which has a state where the crystalline particles of uniform particle size are uniformly distributed over the whole area of a coating film of a magnetic medium formed on the substrate and to be able to cope with the future tendency to have high recording density. SOLUTION: This glass ceramic constituting the information magnetic storage medium contains crystals of the oxide of at least one element selected from among Fe, Cr, Mn, Co, Ni, Cu and V as the component.

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 in an information storage device, and more particularly to a fine metal oxide suitable for forming a magnetic medium film used for a substrate having a magnetic medium film formed thereon. The present invention relates to a glass ceramic substrate for an information magnetic storage medium on which crystals are deposited. 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, multimedia of personal computers and the spread of digital video cameras, digital cameras, etc. are rapidly advancing, and large-capacity information magnetic storage devices are required to handle large-sized data such as moving images and voices. It has been demanded. In order to cope with this, it is indispensable to make the magnetic film finer in order to increase the bit and track densities of the information magnetic storage medium, reduce the size of the bit cells and increase the areal recording density.

A conventional Al alloy substrate is obtained by applying a Ni-P plating, forming a magnetic medium film thereon, and forming a protective layer and a lubricating layer as necessary. In general, a magnetic medium film is directly formed on a substrate surface. However, in a situation where recording density has been remarkably improved in recent years, N
Al alloys with a magnetic medium film formed on the i-P plating and tempered glass or glass ceramics with a magnetic medium film formed directly on the substrate may be used in future applications due to the large crystal grains of the magnetic medium film. There is a limit in increasing the magnetic properties and the magnetic properties. That is, in increasing the recording density of magnetic recording, miniaturization of crystal grains of a magnetic medium film formed on a substrate is a key. On the other hand, magnetic heads are moving closer to the use of near-contact recording and further contact recording methods, which operate closer to the disk surface due to the reduction in bit cells.

Conventionally, an aluminum alloy substrate widely used as a substrate material for a magnetic disk is a soft material and has a low Young's modulus and a low surface hardness, so that it is easily deformed by vibration generated during high-speed rotation of a drive, and is suitable for thinning. Therefore, there is a great problem in application to high-density recording in the future.

On the other hand, as materials for solving the problems of the aluminum alloy substrate, chemically strengthened glass aluminosilicate glass 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. (2) Due to chemical strengthening by ion exchange, N
Since a large amount of the a ₂ O and K ₂ O components is contained as an essential component, the alkali component is eluted at the time of film formation, and the characteristics (uniformity of crystal grain size, orientation, etc.) of the particles of the magnetic medium coating deteriorate. Would. In addition, the reinforced phase causes a temporal change such as diffusion into the magnetic medium film over a long period of use, thereby deteriorating magnetic properties. To prevent this, Na
₂ O, there is entirely barrier coat process for K ₂ O elution preventive but a disadvantage low cost stable production of the product is difficult.

Further, some crystallized glasses have been 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. Japanese Patent Application Laid-Open No. 9-77531 discloses Si
_{O 2 -Al 2 O 3 -MgO-} ZnO-TiO 2 based crystallized glass is disclosed. This crystallized glass has a high Al ₂ O ₃ content of 20% or more, and thus has a large amount of spinel crystals ((Mg / Zn) Al ₂ O ₄ ) precipitated as a main crystal phase, and has a very high hardness. And has a problem in polishing workability.

When a magnetic medium film is directly formed on the conventional substrate as described above, the crystal grains of the magnetic medium film do not become uniform and fine crystal particles until a high-density recording can be performed in the future. There is a limit to memory density. In other words, there is a technique of forming fine metal particles or fine metal oxide particles as nuclei in crystal formation of a magnetic medium film on a chemically strengthened glass or glass ceramic substrate (evaporation, sputtering, etc.). It is difficult to form particles having a uniform particle size in a uniform distribution state over the entire area above, and lacks productivity and stability.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a substrate for an information magnetic storage medium which solves the above-mentioned drawbacks of the prior art and can cope with a tendency to increase the recording density in the future.

[0009]

Means for Solving the Problems The present inventor has conducted intensive tests and researches to achieve the above object, and as a result, a glass ceramic substrate on which a fine metal oxide crystal containing a specific element as a constituent element is deposited. Have found that they have a remarkable effect in reducing the crystal grain size of the magnetic medium film, and have reached the present invention. In the present invention, the spinel crystal is (Mg and / or Zn) Al ₂ O ₄ or (Mg and / or Zn) ₂ TiO ₄ , or
And shows a solid solution between the crystal, Yuktobanian descriptor and tight _{Li 2 O · Al 2 O 3} · 2SiO 2 ( where Li ₂ O
Can be replaced with MgO and / or ZnO)
The solid solution of each crystal means that a component other than the constituent component is partially substituted or dissolved in each crystal.

That is, according to the first aspect of the present invention, there is provided a glass ceramic constituting an information magnetic storage medium,
A glass-ceramic substrate for an information magnetic storage medium, comprising a metal oxide crystal containing at least one element selected from the group consisting of Fe, Cr, Mn, Co, Ni, Cu, and V as a component. According to a second aspect of the present invention, there is provided a glass ceramic constituting an information magnetic storage medium, wherein α-Fe ₂ O ₃ , γ-Fe ₂ O ₃ , RxF
e ₂ O ₄ (spinel ferrite crystal), RxCr ₂ O
₄ (spinel chromium crystals), 2RxO · TiO ₃ or RXO · TiO ₂ (where, Rx is Fe, Cr, Mn,
2. The information magnet according to claim 1, wherein at least one element selected from Co, Ni, Cu, and V) or at least one element selected from solid solutions of these crystals is included. A glass ceramic substrate for a storage medium, wherein the invention according to claim 3 is a glass ceramic constituting an information magnetic storage medium, wherein the metal oxide crystal or a solid solution of the metal oxide crystal has a crystal grain size of 10 ° to 500 °. The glass ceramics substrate for an information magnetic storage medium according to claim 1 or 2, wherein the glass ceramics constituting the information magnetic storage medium has a main crystal phase. Lithium disilicate, α-quartz, α-cristobalite, β-quartz, β-spodumene, β-eucryptite, koji At least one selected from ferrite, enstatite, spinel crystals, MgTi ₂ O ₅ or forsterite, or a solid solution of these crystals.
A glass ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 3, characterized in that the glass ceramic substrate comprises an information magnetic storage medium. 4. The main crystal phase according to claim 1, wherein the phase having the highest precipitation ratio is lithium disilicate, α-quartz or α-cristobalite, or a solid solution of these crystals. A glass ceramic substrate for a magnetic storage medium,
According to a sixth aspect of the present invention, in the main crystal phase of the glass ceramic constituting the information magnetic storage medium, the phase having the highest precipitation ratio is β-quartz, β-spodumene or β-quartz.
-The glass ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 3, wherein the glass ceramic substrate is eucryptite or a solid solution of these crystals. Among the main crystal phases of the glass ceramic constituting the magnetic storage medium, the phase having the highest precipitation ratio is cordierite, enstatite, MgTi ₂ O ₅ ,
The glass ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 3, wherein the substrate is a spinel crystal or forsterite, or a solid solution of these crystals. The composition of the glass ceramics constituting the information magnetic storage medium is expressed in terms of mass percentage in terms of oxides: SiO ₂ 70 to 80% Li ₂ O 5 to 10% Na ₂ O 0 to 1% K ₂ O 0 to 5% MgO 0 0~5% 5% ZnO CaO 0~5% SrO 0~5% BaO 0~5% , however, MgO + ZnO + CaO + SrO + BaO 1~5% Al 2 O 3 5~10% P 2 O 5 1~3% TiO 2 0~5 _{% ZrO 2 0~7% SnO 2 0~3} % as 2 O 3 0~2% Sb 2 O 3 0~2% Fe, Cr, Mn, Co, Ni, Cu, 1 or more selected from among V Element money The glass ceramic substrate for an information magnetic storage medium according to claim 5, characterized in that the glass ceramic substrate contains 2 to 8% of a metal oxide.
In the invention described in (1), the composition of the glass ceramic constituting the information magnetic storage medium is as follows: SiO ₂ 50 to 62% Li ₂ O 3 to 5% MgO 0.5 to 2% ZnO 0.2 ~2% CaO 0.3~4% BaO 0.5~4% TiO 2 1~4% ZrO 2 1~4% P 2 O 5 5~10% Al 2 O 3 22~26% As 2 O 3 0 _{~2% Sb 2 O 3 0~2%} Fe, Cr, and characterized in that it contains Mn, Co, Ni, Cu, 2-8% metal oxides of one or more elemental selected from among V The glass ceramic substrate for an information magnetic storage medium according to claim 6, wherein
The invention described in the mass percentage of the composition of the glass ceramics in terms of oxide constituting the magnetic information storage _{medium, SiO 2 30~65% Al 2 O} 3 5~25% ZnO 0~30% MgO 0~30% CaO 0~15% SrO 0~15% BaO 0~15 % TiO 2 2~15% La 2 O 3 0~10% Y 2 O 3 0~10% Gd 2 O 3 0~10% Ta 2 O 5 0 _{~10% Nb 2 O 5 0~10%} WO 3 0~10% ZrO 2 0~4% P 2 O 5 0~5% SnO 2 0~2% , _{however, ZrO 2 + P 2 O 5} + SnO 2 0 _{~7% as 2 O 3 0~2%} Sb 2 O 3 0~2% Fe, Cr, Mn, Co, Ni, Cu, metal oxides of one or more elemental selected from among V 2 to 8 8. The glass ceramic substrate for an information magnetic storage medium according to claim 7, wherein

The reasons for limiting the type and crystal grain size, main crystal phase, composition range, and the like of suitable metal oxide crystals in the glass ceramic of the present invention are described below. The composition is shown in terms of mass percentage on an oxide basis as in the raw glass.

First, a metal oxide crystal will be described.
In order to obtain a magnetic medium film, the constituent elements of the magnetic medium film in the glass ceramic are the same as those of the conventional method of forming a metal oxide on a glass ceramic substrate (evaporation, sputtering, etc.) as described above. Alternatively, it was considered effective to precipitate homogeneous and fine metal oxide crystals of the same kind in a uniformly dispersed state, and as a result of conducting a test study, it was found that Fe, C
Those having a metal oxide crystal containing at least one or more elements selected from r, Mn, Co, Ni, Cu, and V as constituents had remarkable effects.

Among them, α-Fe ₂ O ₃ , γ-Fe ₂ O ₃ , Rx
Fe ₂ O ₄ (spinel type ferrite crystal), RxCr ₂ O ₄
(Spinel chromium crystal), 2RxO.TiO ₃ or RxO.TiO ₂ (where Rx is Fe, Cr, Mn,
At least one or more elements selected from Co, Ni, Cu, and V), or those containing at least one or more selected from solid solutions of these crystals are close to the components of the magnetic recording medium. Since it is also excellent in compatibility, it is more preferable in terms of uniformity of the crystal grain size and miniaturization of the magnetic medium film.

The metal oxide crystal or the solid solution of the metal oxide crystal preferably has a particle size of 10 to 500 ° corresponding to the crystal particles of the magnetic medium coating. If the angle is less than 10 °, the productivity of the magnetic medium film is low, and the effect is reduced in the uniformity of the crystal grain size of the magnetic medium film. 500
If Å is exceeded, the magnetic film particles are contradictory to miniaturization.

Next, regarding the main crystal phase of the glass ceramic constituting the information storage medium, the mechanical strength (Young's modulus, Vickers hardness, bending strength, etc.) required for the glass ceramic substrate for the magnetic storage medium, the desired range In order to satisfy a wide range of surface roughness and other physical properties (coefficient of thermal expansion, specific gravity, heat resistance, chemical durability)
Lithium disilicate, α-quartz, α-cristobalite, β-quartz, β-spodumene, β-eucryptite, cordierite, enstatite, spinel crystal, MgTi ₂ O ₅ or forsterite, or a solid solution of these crystals It is desirable to include at least one member selected from the group consisting of: That is, desired physical property values can be obtained by controlling the precipitation of these precipitated crystal phases. Furthermore, with these choices,
The degree of freedom in selecting the desired physical property range can be widened. The control of the precipitation of these crystal phases (crystal seed, crystal grain size, crystal precipitation amount, crystal precipitation ratio) is performed by controlling the raw material composition and the heat treatment.

For example, it is necessary to have a range (+ 40 × 10 ⁻⁷ to + 130 × 10 ⁻⁷ / ° C.) which has appropriate mechanical strength and polishing workability while having a low specific gravity and has a relatively large thermal expansion coefficient. In this case, the phase having the highest precipitation ratio in the main crystal phase is preferably lithium disilicate, α-quartz or α-cristobalite, or a solid solution of these crystals. More preferably, the phase having the highest precipitation ratio is lithium disilicate or lithium disilicate, and the phase having the second highest precipitation ratio is α-quartz or α-cristobalite, or a solid solution of these crystals.

Further, it has excellent mechanical strength and heat resistance,
Range where the coefficient of thermal expansion is small (−10 × 10 ⁻⁷ to + 25 × 1)
(0 ⁻⁷ / ° C.), the phase having the highest precipitation ratio in the main crystal phase is preferably β-quartz, β-spodumene or β-eucryptite, or a solid solution of these crystals. More preferably, the phase having the highest precipitation ratio is β-quartz or β-quartz solid solution, and the phase having the second highest precipitation ratio is β-spodumene or β-eucryptite, or a solid solution of these crystals.

Furthermore, it has excellent mechanical properties, heat resistance and polishing workability, while having a relatively low specific gravity, and has a coefficient of thermal expansion in a very good range (+ 25 × 1).
0 ⁻⁷ to + 60 × 10 ⁻⁷ / ° C.), the phase having the largest precipitation ratio among the main crystal phases is cordierite, enstatite, MgTi ₂ O ₅ or forsterite, or a crystal of these crystals. It is preferably a solid solution. Further, (1) the phase having the highest precipitation ratio is cordierite or cordierite solid solution, and the phase having the second highest precipitation ratio is enstatite, MgTi ₂ O ₅ or forsterite, or a solid solution of these crystals. The phase with the highest precipitation ratio is enstatite or enstatite solid solution, and the phase with the highest precipitation ratio is cordierite,
In the case of MgTi ₂ O ₅ or forsterite, or a solid solution of these crystals, (3) the phase with the highest precipitation ratio is MgTi ₂ O ₅ or MgTi ₂ O ₅ solid solution, and the phase with the next highest precipitation ratio is cordierite or Enstar. Either tight or forsterite, or a solid solution of these crystals, is more preferable.

Next, regarding the composition of the glass ceramic constituting the information storage medium, one of the aspects of the present invention, the phase having the highest precipitation ratio among the main crystal phases of the glass ceramic, is lithium disilicate, α- The reasons for limiting the composition range of quartz or α-cristobalite, or a glass ceramic substrate which is a solid solution of these crystals, will be described below.

The SiO ₂ component is a very important factor that, when the raw glass is heat-treated, forms lithium disilicate, α-quartz or α-cristobalite, or a solid solution of these crystals, which is the phase having the highest precipitation ratio in the main crystal phase. If the amount of the component is less than 70%, the precipitated crystal of the obtained glass ceramic is unstable and the structure is liable to be coarsened. If it exceeds 80%, the melting and forming properties of the raw glass become difficult.

The Li ₂ O component is a very important component that forms lithium disilicate or a lithium disilicate solid solution crystal precipitated as a main crystal phase by heat treatment of the raw glass. Precipitation of lithium silicate or lithium disilicate solid solution crystals becomes difficult, and at the same time, melting of the original glass becomes difficult. If it exceeds 10%, the obtained crystals are unstable, the structure is easily coarsened, and the chemical durability is deteriorated. I do.

The Na ₂ O and K ₂ O components are components that improve the melting property of the glass and also prevent coarsening of precipitated crystals, but are 1% in Na ₂ O and 5% in K ₂ O.
If each of these amounts exceeds these amounts, the deposited crystals become coarse, the crystal phase changes, and the chemical durability deteriorates. The K ₂ O component has an effect of suppressing the diffusion of the alkali component by mixing with the Li ₂ O component, and has an effect of preventing alkali elution (diffusion of the alkali component) into the magnetic medium coating.

MgO, ZnO, CaO, SrO, BaO
The component is a component that improves the melting property of glass and precipitates crystal particles of lithium disilicate, α-quartz or α-cristobalite as a main crystal phase, or a solid solution of these crystals in a spherical particle form. If the total amount is less than 1%, the above effect cannot be obtained, and if it exceeds 5%, desired crystals are difficult to precipitate.

In the present invention, the P ₂ O ₅ component is indispensable as a crystal nucleating agent, but if its amount is less than 1%, crystal nucleus formation is insufficient and the precipitated crystal phase becomes coarse, and 3% If it exceeds, the mass productivity is deteriorated due to the opacification of the raw glass.

The components of TiO ₂ , ZrO ₂ and SnO ₂ are P ₂ O ₅
In addition to functioning as a crystal nucleating agent for the glass like the component, it is a component that has a remarkable effect on refinement of precipitated crystals and improvement of the mechanical strength and chemical durability of the material,
It is sufficient that the TiO ₂ component is within 5%, and the ZrO ₂ component is
If it exceeds 7%, it becomes difficult to melt the raw glass, and Z
Undissolved residues such as rSiO ₄ are generated. An SnO ₂ content of 3% or less is sufficient. Incidentally, ZrO ₂ is preferably ₂ to 7%.

The total amount of ZrO ₂ + P ₂ O ₅ + SnO ₂ is preferably 0 to 7% in order to obtain a glass ceramic substrate having suitable physical properties.

The Al ₂ O ₃ component is a component for improving the chemical durability and hardness of the glass ceramic. If the content is less than 5%, the above effects cannot be obtained. Devitrification deteriorates.

As ₂ O ₃ , Sb ₂ O ₃ and the components can be added as fining agents when the glass is melted, but amounts of 2% or less are sufficient.

Fe, Cr, Mn, Co, Ni, Cu, V
At least one or more metal oxide components selected from
Fine crystals suitable for magnetic medium film formation after crystallization,
That is, α-Fe ₂ O ₃ , γ-Fe ₂ O ₃ , RxFe ₂ O
₄ (spinel type ferrite crystal), RxCr ₂ O ₄ (spinel type chromium crystal), 2RxO.TiO ₃ or Rx
O.TiO ₂ (where Rx = Fe, Cr, Mn, Co,
Ni, Cu, V) or an important component for precipitating at least one selected from solid solutions of these crystals, and the total amount of one or more of these metal element oxides is less than 2% In this case, the above effect cannot be obtained, and if it exceeds 8%, the crystal grains become coarse and the devitrification of the glass deteriorates.

Next, one of the aspects of the present invention, the phase having the highest precipitation ratio in the main crystal phase of the glass ceramic is β-quartz, β-spodumene or β-eucryptite, or a solid solution of these crystals. The reason why the composition range of a certain glass ceramic substrate is limited as described above will be described below.

The SiO ₂ component is formed by β-quartz, β-quartz solid solution, β-spodumene, β-spodumene solid solution, which precipitates as a main crystal phase by heat treatment of the raw glass.
β-eucryptite (however, part of Li ₂ O is MgO
And / or ZnO) or a β-eucryptite solid solution (a part of Li ₂ O can be replaced with MgO and / or ZnO). If it is less than 50%, the precipitated crystals of the obtained glass ceramic are unstable and the structure is liable to be coarsened. As a result, the mechanical strength is reduced and the surface roughness obtained by polishing is increased. On the other hand, if it exceeds 62%, the melting and forming properties of the raw glass become difficult, and the homogeneity decreases.

The P ₂ O ₅ component has the effect of improving the melting and refining properties of the raw glass by coexisting with the SiO ₂ component, but if the amount is less than 5%, the above effects cannot be obtained. %, The devitrification resistance of the raw glass decreases, which causes the structure of the glass ceramics to become coarse in the crystallization stage and lowers the mechanical strength.

If the content of the Al ₂ O ₃ component is less than 22%, it becomes difficult to melt the original glass, so that the homogeneity of the obtained glass ceramics is reduced and the chemical durability of the glass ceramics is also deteriorated. Also, if it exceeds 26%, the melting property of the raw glass also deteriorates and the homogeneity decreases,
The devitrification resistance of the raw glass is reduced, which causes the structure of the glass ceramic to become coarse in the crystallization stage, thereby lowering the mechanical strength.

The three components Li ₂ O, MgO and ZnO are β
-Quartz solid solution, β-spodumene, β-spodumene solid solution, β-eucryptite or an important component that is a component of β-eucryptite solid solution, and at the same time, significantly improves the melting property and clarity of the raw glass. When the amount of the Li ₂ O component is less than 3%, the above effects cannot be obtained, and the homogeneity is lowered due to the lowering of the melting property. It becomes difficult to do. On the other hand, if the content exceeds 5%, the above effect cannot be obtained, and the devitrification resistance of the raw glass is reduced. This causes the structure of the glass ceramic to be coarsened in the crystallization stage, thereby lowering the mechanical strength. .

If the amount of the MgO component is less than 0.5%, the above effect cannot be obtained, and if it exceeds 2%, the crystal becomes coarse. If the amount of the ZnO component is less than 0.2%, the above effects cannot be obtained, and if it exceeds 2%, the above effects cannot be obtained, and the devitrification resistance of the raw glass is reduced. During the crystallization stage, the structure of the glass ceramics becomes coarse,
The mechanical strength is reduced.

The two components CaO and BaO basically remain as a glass matrix other than the crystals precipitated in the glass, and are important as components for improving the melting property and finely adjusting the glass matrix phase. If the amount is less than 0.3%, this effect cannot be obtained. Also 4
%, The target crystal phase cannot be obtained, and the resistance to devitrification of the raw glass further decreases. This causes the structure of the glass ceramics to become coarse in the crystallization stage, thereby lowering the mechanical strength. Would.

If the content of the BaO component is less than 0.5%, the above effect cannot be obtained. If the content is more than 4%, the devitrification resistance of the raw glass deteriorates. The structure becomes coarse and the mechanical strength is reduced.

Both the TiO ₂ and ZrO ₂ components are indispensable as a crystal nucleating agent, but if their amounts are less than 1%, desired crystals cannot be precipitated.
If each exceeds 4%, the melting property of the raw glass deteriorates and the homogeneity decreases, and in the worst case, insolubles are generated.

The As ₂ O ₃ and Sb ₂ O ₃ components can be added as a fining agent at the time of glass melting to obtain a homogeneous product.
An amount of 2% or less is sufficient for each. Preferably A
_{s 2 O 3 + Sb 2 O} 3 0 to 2%, more preferably As ₂ O ₃
Is 0 to 2%.

Fe, Cr, Mn, Co, Ni, Cu, V
At least one or more metal oxide components selected from
As described above, as a sub-crystal after crystallization, a fine crystal suitable for forming a magnetic recording medium, that is, α-Fe
₂ O ₃ , γ-Fe ₂ O ₃ , RxFe ₂ O ₄ (spinel ferrite crystal), RxCr ₂ O ₄ (spinel chromium crystal),
2RxO.TiO ₃ or RxO.TiO ₂ (However, R
x = Fe, Cr, Mn, Co, Ni, Cu, V) or an important component for precipitating at least one or more crystals selected from these, and one or two of oxides of these metal elements If the total amount of the seeds is less than 2%, the above effect cannot be obtained. If the total amount exceeds 8%, the crystal grains become coarse and the devitrification of the glass deteriorates.

Incidentally, in addition to the above components, fine adjustment of the characteristics and the like were performed.
As a result, the characteristics of the glass ceramic substrate of the present invention are impaired.
SrO, B within the range not to_TwoO_Three, F_Two, La_TwoO_Three, B
i_TwoO _Three, WO_Three, Y_TwoO_Three, Gd_TwoO_Three, SnO_TwoIn the ingredients
At least one or more selected from up to 2% can be added.

Next, one of the aspects of the present invention, the phase having the largest precipitation ratio among the main crystal phases of glass ceramics, is cordierite, enstatite, MgTi ₂ O ₅ or forsterite, or a solid solution of these crystals. The reason for limiting the composition range of a certain glass ceramic substrate will be described below.

First, the SiO ₂ component is a cordierite, a cordierite solid solution, an enstatite, an enstatite solid solution, a β-quartz, a β-quartz solid solution, a forsterite or a forsterite solid solution which are precipitated as a main crystal phase by heat treatment of the raw glass. Although it is a very important component for forming crystals, if the amount is less than 30%, the precipitated crystal phase of the obtained glass ceramics is unstable and the structure becomes coarse. Moldability becomes difficult.

The MgO and ZnO components are formed by cordierite, cordierite solid solution, enstatite, enstatite solid solution, β-quartz or β-quartz solid solution crystal which precipitates as a main crystal phase by heat treatment of the raw glass,
Spinel ((Mg and / or Zn) (Al and / or
Or Ti) ₂ O ₄ ) or a spinel solid solution ((Mg and / or Zn) (Al and / or Ti) ₂ O ₄ solid solution). If each exceeds 30%, the devitrification deteriorates.

The Al ₂ O ₃ component can be formed by cordierite, a cordierite solid solution or β-quartz solid solution crystal precipitated as a main crystal phase by heat treatment of the raw glass, or spinel ((Mg and / or Zn) (Al and / or Ti) ₂ O ₄ ) or a spinel solid solution ((Mg and / or Zn) (Al and / or Ti) ₂ O ₄ solid solution) is a very important component. The resulting crystalline phase of the obtained glass ceramic is unstable, the structure is likely to be coarse, and the melting property is further deteriorated. If it is 25% or more, the meltability and devitrification of the raw glass deteriorate, and the precipitation amount of spinel becomes abnormally large, so that the hardness becomes unnecessarily high and the workability in polishing or the like is remarkably reduced. In addition, Al
₂ O ₃ is preferably less than 20%.

The CaO, SrO, and BaO components are effective for improving the melting and molding properties of the raw glass and for improving the devitrification resistance, but each content of 15% or less is sufficient.

The TiO ₂ component is indispensable as a crystal nucleating agent, but if the amount is less than 2%, desired crystals cannot be precipitated. If each exceeds 15%, the melting property of the raw glass deteriorates and the homogeneity decreases, and in the worst case, insolubles are generated.

La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , Ta ₂ O ₅ ,
Nb ₂ O ₅ and WO ₃ components are effective for improving the melting and molding properties of the raw glass and for improving the devitrification resistance, and at the same time, have the effect of increasing the rigidity of the material.
% Or less is sufficient, and if each exceeds 10%, the precipitated crystal phase is rather coarsened and the devitrification of the glass is extremely deteriorated. Preferably, the total amount of one or more of these components is within 10%.

The components ZrO ₂ , P ₂ O ₅ and SnO ₂ are TiO ₂
In addition to functioning as a crystal nucleating agent for the glass like the component, it is a component that has a remarkable effect on refinement of precipitated crystals and improvement of the mechanical strength and chemical durability of the material,
4% or less is sufficient for the ZrO ₂ component and 5% for the P ₂ O ₅ component.
% Is sufficient, and the content of the SnO ₂ component is sufficient within 2%.

The Sb ₂ O ₃ and As ₂ O ₃ components are used as fining agents when the glass is melted.

Fe, Cr, Mn, Co, Ni, Cu, V
At least one or more metal oxide components selected from
As described above, as a sub-crystal after crystallization, a fine crystal suitable for forming a magnetic recording medium, that is, α-Fe
₂ O ₃ , γ-Fe ₂ O ₃ , RxFe ₂ O ₄ (spinel ferrite crystal), RxCr ₂ O ₄ (spinel chromium crystal),
2RxO.TiO ₃ or RxO.TiO ₂ (However, R
x = Fe, Cr, Mn, Co, Ni, Cu, V) or an important component for precipitating at least one kind of crystal selected from solid solutions of these crystals. If the total amount of the seeds or two or more is less than 2%, the above effect cannot be obtained, and if it exceeds 8%, the crystal grains become coarse and the devitrification of the glass is deteriorated.

It is preferable that these various substrates mentioned above do not contain environmentally unfavorable PbO components. In the main crystal phase, the phase having the highest precipitation ratio is lithium disilicate, α-quartz or α-cristobalite, or a solid solution of these crystals, except for a glass-ceramic substrate for an information magnetic storage medium. ₂ O, is better not include K ₂ O component preferably.

[0053]

Next, a preferred embodiment of the present invention will be described. Tables 1 to 3 show the composition (mass percentage), crystal phase, crystal grain size, Young's modulus, and polished surface of the glass ceramic substrate 1-9 for an information magnetic storage medium of the present invention on which fine metal oxide crystals were deposited. Roughness (Ra). Figure-
1 shows an XRD diffraction pattern (X-ray diffraction chart) of Example 2, and FIG. 2 shows an XRD diffraction pattern (X-ray diffraction chart) of Example 4.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

In each of the glasses of the above embodiments of the present invention, raw materials such as oxides, carbonates, nitrates and hydrochlorides are mixed, and this is mixed at a temperature of about 1350 to 1550 ° C. using an ordinary melting apparatus. After melting and homogenizing for 3 to 10 hours, the mixture was shaped into a disk and cooled to obtain a glass molded body. Thereafter, this was heat-treated at 450 to 850 ° C. for about 1 to 12 hours to form a crystal nucleus, and then heat-treated at 740 to 950 ° C. for about 1 to 12 hours to cause crystallization (nucleus growth) to obtain a desired glass ceramic. . Next, the above glass ceramic was subjected to an average particle size of 5 to 30 μ
The lapping was carried out for about 10 to 60 minutes by a conventional method using abrasive grains of m, and then polished with cerium oxide having an average particle diameter of 0.1 to 2 μm for about 30 to 60 minutes to finish.

As shown in Tables 1 to 3, the glass-ceramic substrate of the present invention contains a suitable fine metal oxide crystal, and when a magnetic medium film is formed on this substrate, a method similar to that of a conventional substrate is used. As a result, a magnetic medium film having a fine crystal grain size with higher uniformity than the crystal grain size of the magnetic medium film formed in the step was obtained. This is effective for improving high density recording in the future.

[0059]

As described above, according to the present invention, while eliminating the above-mentioned disadvantages of the prior art, a fine metal containing a specific element as a constituent element, which is important for a future increase in storage density, will be described. A glass-ceramic substrate for an information magnetic storage medium can be obtained which contains an oxide crystal and can give an excellent fine structure in forming a magnetic medium film.

[Brief description of the drawings]

FIG. 1 shows an XRD diffraction pattern (X-ray diffraction chart) of Example 2 of the present invention. The horizontal axis indicates 2θ (°), and the vertical axis indicates diffraction intensity (one scale = 200 cps).

FIG. 2 shows an XRD diffraction pattern (X-ray diffraction chart) of Example 4 of the present invention. The horizontal axis indicates 2θ (°), and the vertical axis indicates diffraction intensity (one scale = 200 cps).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Minamikawa 1-15-30 Koyama, Sagamihara-shi, Kanagawa F-term in Ohara Co., Ltd. (Reference) 4G062 AA11 BB01 BB06 CC04 CC09 DA05 DA06 DA07 DB03 DB04 DC01 DD01 DD02 DD03 DE01 DE02 DE03 DE04 DF01 EA01 EA03 EB01 EB02 EC01 EC02 EC03 ED01 ED02 ED03 ED04 EE01 EE02 EE03 EE04 EF01 EF02 EF03 EF04 EG01 EG02 F01 FF02 FG02 F01 FF02 FF02 FF01 FF02 FJ03 FK01 FK02 FK03 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH04 HH05 HH07 HH08 HH09 HH10 HH11 HH12 HH13 HH15 HH17 JJ01 JJ03 JJ04 JJ05 JJ07 KK01 KK03 Q04 Q03 Q03 Q03 Q03 Q03 Q33

Claims (10)

[Claims] 1. A glass ceramic constituting an information magnetic storage medium, comprising Fe, Cr, Mn, Co, Ni, C
A glass-ceramic substrate for an information magnetic storage medium, comprising a metal oxide crystal containing at least one element selected from u and V as a constituent component. 2. A glass ceramic constituting an information magnetic storage medium, comprising α-Fe ₂ O ₃ , γ-Fe ₂ O ₃ , RxF
e ₂ O ₄ (spinel ferrite crystal), RxCr ₂ O
₄ (spinel chromium crystals), 2RxO · TiO ₃ or RXO · TiO ₂ (where, Rx is Fe, Cr, Mn,
2. The information magnet according to claim 1, wherein at least one element selected from Co, Ni, Cu, and V) or at least one element selected from solid solutions of these crystals is included. Glass ceramic substrate for storage media. 3. A glass ceramic constituting an information magnetic storage medium, wherein a crystal grain size of the metal oxide crystal or a solid solution of the metal oxide crystal is 10 ° to 500 °. 2. A glass ceramic substrate for an information magnetic storage medium according to claim 1. 4. A glass ceramic constituting an information magnetic storage medium, comprising lithium disilicate,
α-quartz, α-cristobalite, β-quartz,
β-spodumene, β-eucryptite, cordierite, enstatite, spinel crystal, MgTi ₂ O ₅
4. The glass-ceramic substrate for an information magnetic storage medium according to claim 1, wherein said glass-ceramic substrate comprises at least one selected from the group consisting of forsterite and a solid solution of these crystals. 5. The main crystal phase of a glass ceramic constituting an information magnetic storage medium, wherein the phase having the highest precipitation ratio is lithium disilicate, α-quartz or α-cristobalite, or a solid solution of these crystals. The glass-ceramic substrate for an information magnetic storage medium according to claim 1, wherein 6. Among the main crystal phases of the glass ceramic constituting the information magnetic storage medium, the phase having the highest precipitation ratio is β.
4. The glass ceramic substrate for an information magnetic storage medium according to claim 1, wherein the glass ceramic substrate is quartz, β-spodumene or β-eucryptite, or a solid solution of these crystals. 7. The main crystal phase of the glass ceramic constituting the information magnetic storage medium, the phase having the highest precipitation ratio is cordierite, enstatite, MgTi ₂ O ₅ , spinel crystal or forsterite, or a solid solution of these crystals. The glass-ceramic substrate for an information magnetic storage medium according to any one of claims 1 to 3, wherein: The composition of claim 8 glass-ceramic constituting the magnetic information storage medium in percent by mass of oxide _{equivalent, SiO 2 70~80% Li 2 O} 5~10% Na 2 O 0~1% K 2 O 0~ 5% MgO 0~5% ZnO 0~5% CaO 0~5% SrO 0~5% BaO 0~5% , however, MgO + ZnO + CaO + SrO + BaO 1~5% Al 2 O 3 5~10% P 2 O 5 1~3% TiO ₂ 0-5% ZrO ₂ 0-7% SnO ₂ 0-3% As ₂ O ₃ 0-2% Sb ₂ O ₃ 0-2% From among Fe, Cr, Mn, Co, Ni, Cu and V 6. The glass-ceramic substrate for an information magnetic storage medium according to claim 5, comprising 2 to 8% of a metal oxide of at least one selected element. 9. The composition of the glass ceramic constituting the information magnetic storage medium is as follows: SiO ₂ 50-62% Li ₂ O 3-5% MgO 0.5-2% ZnO 0.2- 2% CaO 0.3~4% BaO 0.5~4% TiO 2 1~4% ZrO 2 1~4% P 2 O 5 5~10% Al 2 O 3 22~26% As 2 O 3 0~ _{2% Sb 2 O 3 0~2%} Fe, Cr, Mn, Co, Ni, Cu, characterized in that it contains 2 to 8% metal oxides of one or more elemental selected from among V A glass ceramic substrate for an information magnetic storage medium according to claim 6. 10. The composition of the glass ceramic constituting the magnetic information storage medium in percent by mass of oxide _{equivalent, SiO 2 30~65% Al 2 O} 3 5~25% ZnO 0~30% MgO 0~30% CaO 0~15% SrO 0~15% BaO 0~15% TiO 2 2~15% La 2 O 3 0~10% Y 2 O 3 0~10% Gd 2 O 3 0~10% Ta 2 O 5 0~ 10% Nb ₂ O ₅ 0 to 10% WO ₃ 0 to 10% ZrO ₂ 0 to 4% P ₂ O ₅ 0 to 5% SnO ₂ 0 to 2% However, ZrO ₂ + P ₂ O ₅ + SnO ₂ 0 _{7% as 2 O 3 0~2%} Sb 2 O 3 0~2% Fe, Cr, Mn, Co, Ni, Cu, metal oxides of one or more elemental selected from among V 2 to 8% The glass-ceramic substrate for an information magnetic storage medium according to claim 7, comprising: