WO2002004371A1

WO2002004371A1 - Glass composition, and substrate for information recording medium, magnetic disk, information recording/reproducing device and magnetic disk device using the same

Info

Publication number: WO2002004371A1
Application number: PCT/JP2000/004614
Authority: WO
Inventors: Takashi Namekawa; Yukio Saito; Takashi Naito; Tetsuo Nakazawa; Hiroki Yamamoto; Tatsumi Hirano; Yuzo Kozono
Original assignee: Hitachi, Ltd.
Priority date: 2000-07-10
Filing date: 2000-07-10
Publication date: 2002-01-17

Abstract

A glass composition having a Yang's modulus of 90 to 130 Gpa and, in the measurement of Vickers hardness under a load of 500 g, shows the occurrence of a crack from the edge of a dent in a proportion of 50 % or less; a glass composition characterized as comprising an oxide containing, in a mole percentage, that of silicon in 40 to 80 % in terms of SiO2, that of aluminum in 5 to 30 % in terms of Al2O3, and that of sodium in 8 to 20 % in terms of Na2O; and a substrate for an information recording/reproducing medium, a magnetic disk, an information recording/reproducing device and a magnetic disk device using the glass composition. The glass composition can correspond satisfactorily to a high speed rotation of 6,000 rpm and has satisfactory resistance to an impact by a magnetic head.

Description

Description Glass composition, substrate for information recording medium using the same, magnetic disk, information recording / reproducing device, and magnetic disk device

The present invention relates to a novel glass composition, a substrate for an information recording medium, a magnetic disk, an information recording / reproducing device, and a magnetic disk device using the same.

Background art

In the past, a metal aluminum substrate with Ni-P on the surface was used as the counterpart of a magnetic disk mounted on a magnetic disk drive. In recent years, as the capacity of magnetic disk devices has increased, glass substrates have come to be used as magnetic disks. Glass substrates are superior to aluminum substrates in terms of smoothness and flatness, and are hard, which is advantageous in terms of lowering the flying height and impact resistance of the magnetic head. A glass substrate is entirely applied to a small 2.5 "magnetic disk device mounted on a notebook type personal computer. JP-A No. 9-244 9 4 32 Chemical strengthened glass substrate whose glass substrate surface is strengthened by metal ion exchange with Alkali metal as described in As described in No. 1 and Japanese Patent Application Laid-Open No. Hei 7-300340, a crystallized glass substrate is used, which precipitates crystals by heat treatment to achieve high strength. In order to increase the density, that is, to increase the capacity, a high Young's modulus glass substrate described in Japanese Patent Application Laid-Open No. 11-116627, which is considered to be able to cope with high-speed rotation of a disk, has been proposed. Japanese Patent Application Laid-Open Nos. Hei 9-17154 and Hei 10-83531 describe a gas composition having a specific composition. Vinegar has been disclosed.

In recent years, as the performance of personal computers has become higher, the recording capacity of magnetic disk drives has been increasing steadily, and large-capacity hard disk drives have been required. Also, this As a result, it is necessary to reduce the weight of the magnetic disk, increase the rotational speed of the magnetic disk, and lower the flying height of the magnetic head. In order to satisfy these requirements, it is necessary to increase the strength of glass substrate materials used for magnetic disks. Chemically strengthened glass in which the glass surface layer has been strengthened by metal ion exchange with the metal as described in JP-A-7-224384 and JP-A-9-244934. As the temperature of the substrate increases, the movement of alkali metal ions on the surface increases, making it difficult to form a magnetic film by sputtering at a temperature of 200 to 300 ° C. It needs to be suppressed. Further, as described in JP-A-7-18771 and JP-A-7-300340, a crystallized glass substrate in which a crystal is precipitated by heat treatment to increase the strength is a large number of crystals. Due to the inclusion of particles, the smoothness of the glass substrate surface required for the magnetic disk substrate is not sufficient, and the toughness of the glass becomes insufficient due to the mixture of amorphous parts and crystal particles, resulting in a magnetic head. There is a problem that the impact resistance becomes insufficient. In addition, with the large capacity of the magnetic disk, the rotational speed of the magnetic disk has been increased from the current 400 rpm to the future for a glass substrate with an outer diameter of 2.5 inches and a thickness of 0.635 mm. Requires more than 600 rpm or more. As the rotation speed of the glass substrate is increased, the glass substrate is likely to warp or bend, which causes deterioration of the magnetic characteristics of the magnetic disk drive. Therefore, a glass substrate material with a high Young's modulus is required to reduce the amount of warpage and deflection of the glass substrate.

Therefore, in the case of a 2.5-inch glass substrate, the Young's modulus of the glass substrate must be 90 GPa or more in order to minimize the amount of deflection at a high-speed rotation of 600 rpm or more. The Young's modulus of the above-mentioned chemically strengthened glass is not enough at 70 to 85 GPa, and it is difficult to cope with a high-speed rotation of a magnetic disk exceeding 600 rpm. On the other hand, crystallized glass satisfies 85 to 100 OGPa and Young's modulus to some extent, but the cracking rate under a 500 g load by a Pickers hardness meter is as high as 100% and the toughness is high. Due to its small size, there is a problem in impact resistance to a magnetic head.

Therefore, instead of these glass substrates, Japanese Patent Application Laid-Open No. 9-71554 discloses a highly rigid substrate. Japanese Patent Application Laid-Open No. 10-83531 and Japanese Patent Application Laid-Open No. 11-116267 have proposed a glass having a high Young's modulus which is considered to be able to cope with high recording density, that is, high-speed rotation for large capacity recording. This substrate has a Young's modulus of 90 to: L 35 GPa, which is considerably higher than that of a conventional glass substrate, and seems to be satisfactory for high-speed rotation of a magnetic disk. However, among the oxides constituting these high Young's modulus glass substrates, alkaline earth oxides of CaO and MgO are contained in a considerably large amount. Generally, MgO is known as a high Young's Ritsui匕成min with A 1 ₂ 0 _3, but there is no particular problem in slight amount, at 500 g load by the content increases Pitsuka one scan hardness meter The crack occurrence rate becomes 100%, which reduces the impact resistance of the magnetic head to the magnetic disk using these glass substrates, and also makes it difficult to sufficiently satisfy the high-speed rotation of the magnetic disk. It is. An object of the present invention is to provide a glass composition which can sufficiently cope with a high-speed rotation of a magnetic disk and which has excellent impact resistance to a magnetic head, a substrate for an information recording medium using the glass composition, a magnetic disk, An object of the present invention is to provide a recording / reproducing device and a magnetic disk device.

Disclosure of the invention

The present invention is, in molar ratio, from Sani匕物containing 0% 8～L in terms of S i 0 ₂ in terms of 40-80%, 10-3 0% and Na ₂ O in terms of becomes possible, 40% to 80% by translated into S i0 _2, 10 to 30 percent in terms of Al ₂ 〇 _3, in terms of Na ₂ 〇 to in terms 8-20% and Y ₂ 0 ₃ 2 it consists Sani匕物containing 30%, to contain 2-10% in terms of L i ₂ 0 in these compositions, further, 4 from 0 to 80% in terms of Si0 _2, a 1 ₂ 0 ₃ in terms of 5-30%, comprises 1-20% in terms of 8-20%及beauty Li ₂ 0 in terms of _{_{Na 2 0, Sn0 2, Z}} r 0 25 Ti0 2, ZnO there CaO, MgO, the glass composition characterized by comprising an oxide containing 20% or less in one or more of the total amount in terms of each of ^ 10 and ₂ 0 _5.

The present invention is (M is the ίΠΑ group element) M ₂ 0 ₃ containing an oxide of one or more in terms of one to 30% in these compositions mentioned above, 20% in terms of Cs ₂ 〇 Below, K _{2 2} In terms converted to 10% or less and B ₂ 03, characterized in that it comprises one or more 20% or less than 20% in a total metric.

The magnetic disk of the present invention is a magnetic disk comprising at least a glass substrate and an information recording thin film formed directly or via another layer on the surface of the substrate, wherein the glass substrate has a Young's modulus of 90 to 130 GP. a, the thermal expansion coefficient of ^{60~; 100x10- 7 / ° C,} 500 g Kuradzu click incidence from indentation edge portion during Bidzukasu hardness measurement by load is equal to or less than 50%.

Further, it is preferable that the water resistance of the glass measured by JIS-3502 on the glass substrate is 0 to 0.2 mg in terms of alkali elution amount.

In addition to the above-mentioned glass composition as the glass substrate, in a specific magnetic disk device or information recording / reproducing apparatus, as a substrate for an information recording medium having an information recording thin film, the above-mentioned glass composition or S in the molar ratio is used. i 0 ₂ 40 to 80% eight 1 ₂ 0 ₃ 5 30% Na ₂ 0 is 8 to 20% Cs ₂ 0 is 0 to 20% M ₂ 0 ₃ (M is ΠΙΑ group element) is 0 30%, Ln ₂ O ₃ (Ln is a rare earth element) 0 to: A specific combination composed of L0% is desirable. Here, M ₂ O ₃ (M is 111 eight group elements) is ¥ ₂ 0 ₃ is 0-30%, and ₂ 0 ₃ preferably has a 0-30%, La ₂ O ₃ (Ln is a rare earth element ) Is preferably composed of at least one selected from rare earth oxides of Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Furthermore, L i ₂ 〇 0 to 20 mol%, K ₂ 0 is _{0~: L 0%, Β 2} 0 3 is good to contain 0-20%. _{_{Further, Sn0 2, Zr0 2, Ti0}} 2, ZnO, CaO, MgO, that one or more of NiO and V ₂ 0 ₅ is contained 0-20% preferred.

In the present invention, the glass substrate has an average particle size of:! ~ 3 onm of M ₂ 0 ₃ (M is 111 eight group elements) Oyobi 1 ^ ₂ 0 ₃ (Ln is a rare earth element) it is desirable that the fine particles made of is precipitated. The recording surface roughness Ra of the glass is preferably not more than 2. Onm.

Further, the present invention relates to a method of manufacturing a device comprising the steps of: It is preferable that the layer mainly composed of Connoxide has an average particle diameter of 5 to 12 nm and a dispersion (standard deviation / average particle diameter) of 25% or less. Preferably, NaCl-type precipitated crystals are present in this layer.

Further, the present invention provides a magnetic disk comprising at least a glass substrate and an information recording thin film formed on the surface of the substrate by directly or via another layer mainly composed of conox oxide, and records or reproduces information. In a magnetic disk drive provided with a spinning motor for rotating a magnetic disk, the Young's modulus of the glass substrate is preferably 90 to 13 OGPa, and when measuring the Pickers hardness under a load of 500 g for 15 seconds, The crack occurrence rate from the indentation edge portion is 50% or less, and preferably, the coefficient of thermal expansion is 60 to 100 × 10 ¹⁷ /. C: It is desirable that the water resistance of the glass measured by JIS-R3502 is from 0 to 0.2 mg in terms of alkali elution amount.

Further, in the present invention, a magnetic disk having at least a glass substrate and a magnetic thin film formed on the surface opposite to the glass substrate, directly or via another layer, a layer mainly composed of cobalt oxide, and recording or reproducing information. In a magnetic disk drive provided with a magnetic head for rotating a magnetic disk and a spinning drum for rotating a magnetic disk, the glass substrate may be composed of the above-mentioned glass composition or a molar ratio of SiO ₂ 40-80% and Al ₂ O ₃ 5-30. % Na ₂ from 08 to 2 0% Cs ₂ 0 is 0-20%, ^ ₂ 0 ₃ 0 ^ is 111 eight group elements) is 0 to 30% Ln ₂ 0 ₃ (Ln is a rare earth element) is 0 Those having 10% are preferred.

The present invention resides in a glass substrate for a magnetic disk or an optical disk, wherein the Young's modulus is preferably in the range of 90 to 13 OGPa. If the Young's modulus is less than 9 OGPa, the magnetic disk is 2.5 inches in size and the thickness is 0.635 mm.When the disk is rotated at 600 Orpm, the glass bends and the recording / reproduction as a magnetic recording device becomes insufficient. When the magnetic disk is used, when the magnetic disk using the glass substrate rotates at a high speed exceeding 6000 rpm, minute cracks and the like tend to occur due to a decrease in toughness accompanying high rigidity of the glass substrate. Also, the reason the heat Rise expansion coefficient of the glass substrate in the range of 60~100 X 10- ⁷ / ° C is the three 2 from the magnetic disk This is to match the coefficient of thermal expansion of the stainless steel supporter that supports the magnetic disk in the magnetic disk drive made of magnetic disks. Furthermore, the reason why the crack occurrence rate from the wedge part of the indentation when measuring Vickers hardness under a load of 500 g was set to 50% or less is that when the crack occurrence rate exceeds 50%, the impact resistance of the magnetic head to the magnetic disk This is because it is difficult for the magnetic disk to be sufficiently satisfied, and furthermore, when the magnetic disk is rotated at 6000 rpm on a 2.5-inch size glass substrate, cracks and cracks tend to occur on the glass substrate.

In addition, the reason why the water resistance of the glass measured by JIS-R3502 on the above glass substrate is 0.2 mg or less for the glass elution amount is that when the glass elution amount exceeds 0.2 mg, the alkali component is reduced to the surface of the substrate. This has an adverse effect on the information recording thin film (magnetic film) formed directly on the substrate surface and reduces the adhesion with the magnetic film.

Next, the components (molar ratio) of the glass substrate will be described.

S i0 ₂ is a glass forming Sani匕物a component that contribute to the mechanical strength and I匕学stability, assistant engineer glass manufacturing to glass characteristic temperature increases when greater than 80% as glass components In addition, if it is less than 40%, the glass will be devitrified. For this reason, the content of glass S i0 ₂ is in the range of 40% to 80%. In particular, 45 to 70% is preferable.

A 1 ₂ 0 ₃ is a component that contributes to mechanical properties and chemical stability such as high hardness and high rigidity, glass characteristic temperature becomes too high it becomes difficult to glass production exceeds 30% as glass components If it is less than 5%, the mechanical strength of the glass decreases. Therefore, the content of glass A 1 ₂ 0 ₃ is in the range of 5-30%. In a specific glass composition, the content is 10 to 30%.

Na ₂₀ is a component that can lower the characteristic temperature of glass.If the glass component exceeds 20%, the chemical stability of the glass deteriorates and the mechanical properties also decrease, and less than 8% In this case, the mechanical strength of the glass decreases. Therefore, the content of the glass N a ₂ 0 is in the range of 8-20%. Specific glass composition smell 8% to 10%.

Cs ₂ 0 is a component that can lower the characteristic temperature of the glass, the mechanical properties deteriorate with the chemical stability of the glass is deteriorated when it exceeds 20 mol%, the glass component, C s ₂ 0 The glass content is 20% or less, preferably 0.5 to 5%.

Y ₂ 0 ₃ and L a ₂ 0 ₃ is a highly rigid components of the glass, the mechanical properties deteriorate with exceeding 3 0% as a glass component chemical stability of the glass is deteriorated, Y ₂ 0 ₃ and La ₂ 0 content of the glass of ₃ is preferably 30% or less. In a specific composition, the content is 2% or more, more preferably 5% or more, and preferably 20% or less.

L i ₂ 0 is a component that can lower the characteristic temperature of the glass, the mechanical properties deteriorate with the chemical stability of the glass is deteriorated when it exceeds 20 mol%, the glass component, L i ₂ The glass content of 0 should be 20% or less. 2 to 10% or 1 to 20% for specific glass compositions

K ₂ 0 is a component that can lower the characteristic temperature of the glass, the mechanical properties deteriorate with the chemical stability of the glass is deteriorated when it exceeds 10% as a glass component, kappa ₂ 0 Glass The content is preferably 10% or less, more preferably 0.5% or more.

The beta ₂ 0 ₃ is a component that can lower the characteristic temperature of the glass, the mechanical properties deteriorate with the chemical stability of the glass is deteriorated when it exceeds 20% as a glass component, a beta ₂ 0 ₃ The glass content is preferably at most 20%, more preferably at least 0.5%.

The S eta 0 ₂ contributes to the improvement of the glass solubility lowering the high temperature viscosity, Z r 0 ₂ contributes to the chemical stability of the glass, T i 0 ₂ in improving glass solubility lowering the high temperature viscosity Contributing, ZnO chemically stabilizes, and CaO and MgO are components that reduce high-temperature viscosity and improve the solubility of glass. Also, NiO is a component contributing to improving mechanical properties, V ₂ 0 ₅ is also to improve the solubility of the glass lowering the high temperature viscosity as well. Therefore, Sn0 _2, Zr_〇 _2, Ti_〇 ₂ヽZnO, CaO, Mg_〇, one or more of NiO and V ₂ 0 ₅ is preferably comprised more than 20%. Including N a ₂ 0 and L i ₂ 0 It is preferably 0.5 to 10%.

Next, a method for producing the glass of the present invention will be described. First, after mixing a predetermined amount of the glass raw material powder of the above-mentioned glass constituent acid oxide, the mixture was sufficiently stirred and mixed, and melted with stirring using a platinum stirring blade in the air for 10 minutes or more. Processing such as cutting, grinding, polishing, etc., is performed with a glass sprocket to obtain a disk-shaped glass substrate of a predetermined shape. In addition, the obtained plate-shaped glass plate was cut out into a disk shape, and from a semi-molten state, formed into a disk shape using a mold, and lapping and polishing were performed using cerium oxide or the like for precision processing of the surface. Is performed to reduce the surface roughness Ra to 2.0 nm or less.

The magnetic disk of the present invention comprises at least a glass substrate and an information recording thin film (magnetic film) formed directly or via another layer on the surface of the substrate. Figure 1 shows a schematic diagram of the cross section. As shown in the figure, the magnetic disk of the present invention has a glass substrate 1, a seed film 2, an intermediate film 3, a magnetic film 4, a protective film 5, and a lubricating film 6 sequentially formed.

As the film configuration of the magnetic recording medium of the present invention, the seed film 2 is a C0-based metal film, the intermediate film 3 is a Cr—Ti-based alloy film, and the magnetic film 4 is a Co—Cr—Pt-based alloy film. The protective film 5 is a carbon film, or the seed film 2 is an oxide film mainly composed of cobalt oxide as a film structure of the magnetic recording medium. A magnetic recording medium to which an oxide film containing cobalt oxide as a main component is used as a seed film is an in-plane magnetic recording medium, and the Co alloy used for the magnetic film 4 has a hexagonal crystal structure. . Since the C0 alloy film has uniaxial anisotropy in which the c-axis is the axis of easy magnetization, it is necessary to orient the c-axis in the plane of the magnetic film. Therefore, in order to orient the Co—Cr—Pt alloy of the magnetic film 4, the seed film 2 and the intermediate film 3 need to be oriented so as to be coaxial with the magnetic film 4.

As the magnetic disk of the present invention, it is preferable to use an oxide mainly composed of cobalt oxide, which is easily oriented, as the shield film 2 formed on the surface of the glass substrate 1 of the present invention. Further, in the present invention, in the oxidizing film containing the oxidizing cobalt as a main component, In order to sufficiently satisfy the magnetic properties of the conductive film, it is preferable that the average particle size is 5 to 12 nm and the dispersion (standard deviation Z average particle size) is 25% or less. It is preferred that C1-type precipitated crystals exist.

According to the present invention, the Young's modulus is 90 to 130 GPa, and the crack occurrence rate from the indentation edge portion at the time of measuring the Pickers hardness under a 500 g load is 0 to 50%. By using a glass substrate for the magnetic disk, it is possible to sufficiently cope with high-speed rotation of the magnetic disk and to sufficiently satisfy the impact resistance of the magnetic head. By using these magnetic disks, it is possible to provide a magnetic disk device having a large capacity and excellent shock resistance.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of a cross section of a magnetic disk manufactured by the present invention, and FIG. 2 is a schematic diagram of a magnetic disk device manufactured by the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1)

[Table 1] Table 1, Table

Composition (mol%) Young's modulus Cracking Ripe expansion coefficient Shochu aqueous solution

Si02 Λ1203 Y203 La203 Na20 Li20 Cs20 20 B203 Gd203 (GPa) Production rate (%) (X 10) (mg)

A1 60 18 14 8 1 15 50 64 0.15

A2 56 24 10 10 105 40 62 0.2

A3 58 15 15 12 1 10 35 70 0.1

A4 56 22 10 10 2 100 40 83 0.2

A5 52 24 10 9 5 102 50 75 0.16

A6 50 24 10 8 8 113 10 69 0.08

A7 48 24 10 S 6 4 115 20 72 0.13

AS 58 24 10 δ 98 40 65 0.15

A9 60 24 5 9 2 92 35 70 Ο.ίδ

A10 70 10 9 9 1 1 108 30 75 0.18 [Table 2]

Table 2

Tables 1, 3 and 4 show the glass compositions of the present invention, and Table 2 shows the comparative examples (mol%). 200 g of an oxide powder to be a constituent material of each glass shown in the table is blended at a predetermined amount of mol%, and is sufficiently mechanically mixed and put into a platinum crucible. After inserting the platinum crucible into the glass-making furnace, the mixture was heated and melted in air at 160 ° C for 1-2 hours while stirring, the platinum crucible was taken out, and the molten glass was sampled for each property evaluation. It is poured into a graphite 7 70 mm x 10 mm deep board for 20 mm wide x 20 mm deep x 60 mm long and 2.5 inch size substrates. Thereafter, the glass is strained at a temperature higher than the glass transition temperature for about 1 hour, and gradually cooled to room temperature to obtain a glass block. From the obtained glass block having a width of 20 mm x a height of 20 mm x a length of 60 mm, a sample for each property evaluation was processed into a shape required for each property evaluation using a slicing machine or the like.

The Young's modulus was measured at room temperature by the resonance method using a 55 x 2 x 10 glass sample.

The cracking rate was measured using a 15 x 4 x 4 glass sample, and after the glass sample surface was mirror-finished, using a micro Vickers hardness tester, immediately after applying a load of 500 g for 15 seconds. After a lapse of 20 minutes, the occurrence of cracks from the edge of the pits impression was observed. The cracking rate is one of the evaluation methods to evaluate the impact resistance of a magnetic disk consisting of a glass substrate and a magnetic film when a magnetic head and a magnetic disk device fall. In addition, the indentation of Beakers was assumed to be 20 RBIs. Each of the indentations had four wedges, and if cracks were observed from any one of them, the indentation was regarded as cracking.

A glass sample with a thermal expansion coefficient of 15x4x4 was used, and the measurement temperature range was 100 to 400 ° C.

For water resistance, the amount of alkali elution was measured by a method based on JIS-R3502. The alkali elution test method using JIS-R3502 will be described. First, adjust the sample according to the following procedure. Wash the test glass thoroughly, dry it and grind it in an agate mortar. Next, 5 g of a powder passing through a standard sieve of 420 / m and remaining at a standard sieve of 250 zm is taken out, fine powder is removed with ethyl alcohol, dried in an atmosphere at about 125 ° C, and desiccated. Save in the evening. From the sample thus adjusted, weigh exactly the same number of grams as the specific gravity of the test glass. Also, put it in a round bottom flask beforehand.

Add 40 cc of distilled water, keep it in boiling water for 10 minutes or more, put the sample in a flask, wash off the sample attached to the inner surface of the instrument wall with 10 cc of distilled water, and gently rock it. To stabilize the top of the sample stack to maintain a uniform plane. Next, attach a cooler and heat in boiling water for 60 minutes. Next, remove the flask from the water, immediately cool it with running water, transfer the contents to a hard glass beaker, add 3 drops of metal red indicator, and titrate with NZ10 Q sulfuric acid. Perform a blank test in the same way and compare the results. In addition, the obtained results are calculated by multiplying the cc number of NZ100 sulfuric acid consumed c c by subtracting the blank test result by 0.31 and converting it to 20 mg Na.

. N o B. 1 to the comparative example shown in Table 2: B 5 Glass Young's modulus indicates a more 90 GP a, The thermal expansion coefficient indicates the range of 60~100x10- ⁷ / ° C, these It was confirmed that the characteristics described above were satisfied as a glass substrate for a magnetic disk. However, the water resistance of JIS-R3502 is 0.3-0.5mg, and although a little, alkali and alkaline earth elements on the glass substrate surface are liable to be diffused. There is a concern that the adhesion may decrease. In addition, immediately after applying a load of 15 seconds with a load of 500 g using a micro- After 0 minute, Beakers indentation was observed. As a result, the occurrence of cracks was confirmed from the edges of all the indentations, and the crack occurrence rate was 100% in all cases. Therefore, the magnetic disks using the glass Nos. B1 to B5 of the comparative examples cannot sufficiently satisfy the impact resistance due to the magnetic head, and the magnetic disk surface is easily damaged by the magnetic head. Become. No. B. 1 to the Comparative Example; B 5 glass are those which attained high Young Ritsui匕in A 1 ₂ 0 ₃ and Al force re-earth oxides M g 0 and C a 0, alkali Doruisan It is inferred that the crack generation rate was increased because of the high content of MgO and Ca0, which are the stilts. From the results of these comparative examples, it was necessary to develop a glass substrate capable of reducing the crack occurrence rate while maintaining a high Young's modulus by minimizing the content of the alkaline earth oxide.

Therefore, No. A1 to A24 glasses shown in Tables 1, 3 and 4 were found. The glass of the present invention A 1 ₂ 0 ₃ and M ₂ 0 ₃ (M is Iotapai A group elements) a high Young's modulus by the inclusion of Y ₂ 0 ₃ and L a ₂ 〇 ₃ is a further alkali Sani匕物The crack generation rate could be reduced by containing Na ₂ある of 8 mol% or more. No. A1 to A3 S i 0 ₂ _A 1 ₂ 0 ₃ — Y ₂ 〇 ₃ — Na ₂ 0 glass with a Young's modulus of 105 GPa or more, _2.5 inch size, thickness of 0.635 mm Satisfactory for future high-speed rotation of 6000 rpm on glass substrates. In addition, the cracking rate from the edge of the indentation at a load of 500 g measured by a Micro Vickers hardness tester was 50% or less, which was significantly reduced as compared with the No. B1 to B5 glasses of the comparative example. This seems to be sufficient for the impact resistance of the magnetic head. In addition, the coefficient of thermal expansion was in the range of 62 to 70 × 10 ¹⁷ / ° C as in the comparative example, and it was confirmed that the thermal expansion coefficient was sufficiently matched with the stainless steel spacer. In addition, the water resistance in JIS-R 3502 was 0.2 mg or less, indicating that the diffusion of alkali metal elements could be prevented.

Then, C s ₂ 0 and L i ₂ 0 and B ₂ 0 ₃ Young's modulus as N 0. A4-A7 glass containing was said is Al force Li metal oxides, cracking, thermal expansion It was confirmed that the coefficient and the water resistance in JI SR 3502 were satisfactory. Was replaced with La ₂ 0 ₃ cognate the periodic the Y ₂ 0 _3. Similarly, it was confirmed that the No. A8 to A9 glasses were also satisfactory in Young's modulus, crack generation rate, coefficient of thermal expansion, and water resistance in JIS-R3502.

Next, containing Y ₂ 0 ₃ and _{_{_{L a 2 0 3 Gd 2 0}}} 3 of rare-earth element oxide in place of the Al force Li metal oxide K 20 is a III A group elements oxides of the periodic table It was found that each of the properties described above was sufficiently satisfied even in the No. A10 glass.

[Table 3] Table 3

Furthermore, Sn0 ₂ shown in Table _{3, Zr0 2 2, Ti02, ZnO} , CaO, Mg 0, it it contains is not the No. A 1 l~No. A 18 Young's modulus for the glass, the crack generation rate of thermal expansion As a result of measuring the coefficient and the water resistance in JIS-R3502, it was found that the respective characteristics were sufficiently satisfied as described above. Also, similar results were obtained also contain V ₂ 0 ₅ and NiO. _{Here, Sn0 2 + Z 1> 0} 2 +1 1;? [0 2 + 2110 + 〇 _{& 0 + ^ 0 + ¥ 2} 0 5 + ^ content of 10 is good is 20 molar% or less.

Consists S i monument _{_2,} A 1 ₂ 0 ₃ and G d ₂ ◦ ₃ and Al force Li metal oxide of a rare earth element oxide N a ₂ 0 and L i ₂ 0 and alkaline earth oxides MgO and CaO No. Al 9 ~ In the case of No. A20 glass as well, excellent effects could be obtained. Here, in a glass containing at least one of oxides of Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu of rare earth elements other than Gd Also obtained an excellent effect. Furthermore, it was found that the same effect was obtained in a glass containing both a Group IIIA element oxide and a rare earth element oxide in the periodic table.

[Table 4]

Table 4

Next, G d ₂ 0 ₃ wherein the N o of Y ₂ 03 and a rare earth element oxide of III A group elements oxides of the Periodic Table. A 1 to N o. Is contained in a large amount compared to A 20, Gavosu No. A22 to No. A24 glasses were prepared in which the content of SiO _{2 in} the formed oxide was small. As a result of TEM observation of this glass at a magnification of 100,000, fine particles with an average particle diameter of 1 to 3 Onm uniformly dispersed were observed. Analysis of the fine particles, it was confirmed that the fine crystals containing Y ₂ 〇 ₃ and G d ₂ 0 _3. As shown in Table 4, the glass of No. A22 to No. A24 in which the fine particles were precipitated had a higher Young's modulus than the glass A21 in which the fine particles were not precipitated. This is due to the precipitation of fine particles. It was also found that other properties such as crack generation rate, thermal expansion coefficient and water resistance in JIS-R3502 were sufficiently satisfied. Here, no precipitation of fine particles was observed with respect to No. Al to No. A20 glasses which are examples of the present invention.

As described above, it has been confirmed that the glass of the present invention can be sufficiently applied as a substrate for a magnetic disk. (Example 2)

[Table 5] Table 5

No. A6, No. A19, and No. A22 glass, which are examples of the present invention, are used for magnetic disks processed to 2.5-inch size having an outer diameter of 65 mm, an inner diameter of 20 mm, and a thickness of 0.635 mm. A glass substrate was manufactured. At this time, the surface roughness Ra of the glass substrate was set to 2 nm or less, and a magnetic disk was manufactured using this glass substrate. Next, an outline of a method for manufacturing a magnetic disk of the present invention will be described. FIG. 1 is a sectional view of a magnetic disk according to the present invention. On the magnetic disk, a glass substrate 1, a shield film 2, an intermediate film 3, a magnetic film 4, a protective film 5, and a lubricating film 6 are sequentially formed. As an example of the present invention, the surface of the glass substrate 1 of No. A6, No. Al 9s No. A22 described above was prepared by using a sputtering method, and the main component thereof was CoO, which is cobalt oxide. The seed film 2 made of an object film is 15 nm, the intermediate film 3 made of a Cr—Ti alloy is 20 nm, the magnetic film 4 made of a Co—Cr—Pt alloy is 20 nm, and the force-bonding protective film 5 is 10 nm was sequentially formed. At this time, the film was formed at a glass substrate temperature of 250 to 300 ° C. The sputter ring rate of each membrane was set in the range of 1 to 5 nm / ¾>. Furthermore, a perfluoropolyether-based lubricant 6 was applied by diving to produce magnetic disks No. AO 61, No. Al 91 and No. A221 in Table 5.

As a comparative example, No. Bl and No. B2 glasses shown in Table 2 were processed into 2.5-inch magnetic disk substrates. After that, as described above, Magnetic disks No. BO 11 and No. BO 21 were manufactured. Here, a Cr-based metal film was used for the seed film 2 of No. BOil and No. BO21. These magnetic disks were mounted on a 2.5-inch magnetic disk drive. The number of magnetic disks produced was 100 each.

FIG. 2 is a schematic diagram of the magnetic disk drive manufactured in this embodiment. The magnetic disk 7 is supported by a rotating shaft 8, and at the same time, the magnetic disk 7 is rotated by rotating a spindle motor 9. 12 is an output terminal of the electric system. The magnetic head 10 is supported by a head rotation shaft 11, and the position of the disk in the radial direction is determined by the rotation of the head rotation shaft 11. In this embodiment, three magnetic disks are mounted via the spacer 13, and a total of four magnetic heads are arranged on both surfaces of each disk. A spacer made of stainless steel, which is a metal, has been used. The flying height of the magnetic head was controlled at 2 Onm by adjusting the shape of the magnetic head slider and the spring strength of the arm supporting the magnetic head. The rotation speed of the magnetic disk was 6000 revolutions per minute.

No. AO 6 Is No. A191, No. A221, No. B011, No. B021 The system was operated for 100 hours, and the presence or absence of errors due to heat generation at the time of a magnetic head collision and deterioration of magnetic properties due to non-orientation of the magnetic film was examined. Furthermore, the magnetic disk was removed from the magnetic disk device, and the surface of the magnetic disk was observed in detail to determine whether there was damage such as film peeling and, if there was any damage, the state of the damage. As a result, all of the magnetic disks No. AO 61 No. A191 and No. A221 using the glass substrate of the present invention have few errors and damages such as scratches on the surface of the magnetic disk, and the magnetic characteristics such as recording / reproducing are low. A yield of more than 90% was obtained. On the other hand, the magnetic disk Nos. B011 and B021 of the comparative example showed many errors in the high-speed rotation test, and the magnetic characteristic yield of the magnetic disk No. B011 and No. B021 of the comparative example such as recording / reproducing was 56%. It was below. Next, using each of the prepared 20 magnetic disks, a pair of magnetic disks was used.

Impact resistance to check the degree of deterioration of magnetic characteristics due to damage to the magnetic disk when the magnetic disk device is dropped from the height of lm while rotating the disk at 6000 rpm Tested. As a result, magnetic disks No. A061, No. A191, and No. A221 using the glass substrate of the present invention all suffered little damage such as generation of errors due to impact resistance and scratches on the surface of the magnetic disk, and 90% or less. The above yield was able to be obtained. On the other hand, in the magnetic disks No. BO 11 and No. 21 of the comparative examples, many errors in the magnetic characteristics considered to be caused by the impact of the magnetic head when the magnetic disk device was dropped were recognized. The yield of BO 11, No. BO 21 was less than 45%. From these, it was confirmed that the magnetic disk using the glass substrate of the present invention had excellent impact resistance.

As described above, the magnetic disk drive equipped with the magnetic disk using the glass substrate of the present invention can sufficiently increase the capacity of 6000 rotations per minute, thereby increasing the capacity.

In the embodiment of the present invention, a 2.5-inch size glass substrate, a magnetic disk, and a device therefor have been described using the embodiment, but the present invention is also applicable to 1-inch, 3-inch, 3.5-inch or other sizes. It is a technology that can be done.

(Example 3)

This embodiment is an example of an optical disk using a glass composition and an apparatus therefor, as in the second embodiment. The optical disc has a reflective film, a recording film, and a protective film sequentially provided on both sides of a glass substrate, and is further coated with a lubricant. A glass substrate with a diameter of 120 mm and a thickness of 12 mm is used as the glass substrate. 1 over 3% Ding i alloy thin reflective film 100 'in 1111, a recording film (This C o-S i based oxide thin film, of 1 onm in Si_〇 ₂ thin film and lubricant 50nm the protective film A housing of the information recording / reproducing apparatus on which the optical disk is mounted is provided with a spindle motor for rotating the optical disk and an actuator VCM coil for positioning the optical head. The light head is embedded with a calcium titanate-based slider, and is attached to the tip of the actuator. I attached.

In the present embodiment, recording and reproduction on an optical disk are performed using an optical head that generates near-field light. The near-field light is a laser beam having a wavelength of about 1Z10 that leaks out of the focal plane when a laser beam is irradiated onto the spherical surface of a hemispherical lens and the beam is focused.

A hemispherical lens was used as the light head, and a laser beam with a wavelength of 41 Onm was irradiated on the hemispherical lens to obtain near-field light with a diameter of 125 nm. The flying distance of the optical head was set to 5 Onm from the surface of the optical disc, and the near-field light was applied to the optical disc to look at the recording film.

Therefore, if an optical head that rotates at high speed and generates near-field light is used for recording and reproduction on an optical disk, information can be recorded at a higher density and reproduction can be performed with higher accuracy.

Industrial applicability

According to the present invention, a glass substrate characterized by having a Young's modulus of 90 to 90%; a crack occurrence rate from an indentation edge portion at the time of measuring a force of hardness under a load of 30 GPa and 50 Og of 0 to 50%. By using this for a magnetic disk, it is possible to sufficiently cope with high-speed rotation of the magnetic disk and to sufficiently satisfy the impact resistance due to the magnetic head. By using these magnetic disks, it is possible to provide a magnetic disk device having a large capacity and excellent shock resistance.

Claims

The scope of the claims

1. molar ratio, consisting of S I_〇 40% to 80% in terms of _{_2,} A 1 ₂ 0 ₃ in terms of 10 to 30% and Na ₂ 0 in terms of oxide containing 8% to 10% A glass composition characterized by the following.

2. at a molar ratio of 40% to 80% in terms of S i0 _2,. 10 to 30 percent in terms of A 1 ₂ 0 _3, in terms of 8 to 10% and L i ₂ 0 in terms of Na ₂ 0 A glass composition comprising an oxide containing 2 to 10% by weight.

3. molar ratio, 40% to 80% in terms of _{_{S i0 2, A 1 2 0}} 3 in terms of 10~ 30%, Na ₂ 8~10% in terms of ◦ and M ₂ O ₃ (M A glass composition comprising an oxide containing 1 to 30% in terms of IIIA element).

4. molar ratio, 40% to 80% in terms of _{_{S i0 2, A 1 2 0}} 3 in terms of 10 to 30% 8 to 20% in terms of Na ₂ 0 and converted to Y ₂ 0 ₃ A glass composition comprising an oxide containing 2 to 30% by weight.

5. In claim 1, a molar ratio, Rei_3 ₂ 20% hereinafter in terms of 0, 10% or less in terms of kappa ₂ 0 and 8 ₂ 0 ₃ in terms of 20% A glass composition comprising an oxide containing 20% or less in total of one or more of the following.

6. Claims! In any of _{~ 5, Sn0 2, Z r} 0 2, T i 0 2, ZnO, CaO, MgO, in each one or more of the total amount in terms of the NiO and V ₂ 0 ₅ 20 moles %, Which is made of an oxide containing not more than 10% by weight.

7. molar ratio, 40% to 80% in terms of S I_〇 _2, in terms of 5 to 30% Na ₂ 0 in terms of A 1 ₂ 0 ₃ in terms 8 to 20% and 1 ₂ 0 Containing 1-20%, Sn

0 _2, Z r 0 ₂₃ T I_〇 _2, ZnO, CaO, MgO, from in terms of each of the N i 0 and V ₂ 0 ₅ oxide containing 20% or less in one or more of the total amount A glass composition characterized in that:

8. In claim 7, M ₂ 〇 ₃ (M is III A group elements) glass composition characterized by comprising an oxide containing 1 to 30 mol% in terms of.

9. A substrate for an information recording medium, comprising: a glass comprising the glass composition according to any one of claims 1 to 8; and an information recording thin film on the surface.

10. In the substrate for information recording medium having an information recording thin film formed on a glass substrate surface, the Young's modulus is 90 to 13 OGP a of the glass substrate, the thermal expansion coefficient of ^{60 ~100 X 10- 7 / ° C} , A substrate for an information recording medium, wherein a crack occurrence rate when measuring Vickers hardness under a load of 500 g is 50% or less.

11. The information recording medium substrate according to claim 10, wherein the water resistance of the glass measured by JIS-R3502 in the glass substrate is from 0.2 to 0.2 mg as an alkali elution amount.

12. In a magnetic disk having an information recording medium substrate having an information recording thin film formed on a glass substrate surface via a layer containing cobalt oxide as a main component, the glass substrate has a molar ratio of SiO ₂ . San換to 40% to 80%, 5 to 30% in terms of a 1 ₂ 0 _3, 8~20% in terms of Na ₂ 0, 0 to 20% in terms to the Cs _₂ 0, M ₂ 0 ₃ (M is ΙΠΑ group elements) magnetic, characterized in that they are composed of oxides (the Ln rare earth element) 0-30% and Ln ₂ 0 ₃ in terms of containing 0-10% by translated into disk. .

13. The glass substrate, the molar ratio, L i ₂ 0 in terms of 0-20%, in terms of K ₂ 0 0 ~ 10% and beta ₂ 03 in terms of 0 to 20% of one or 13. The magnetic disk according to claim 12, comprising the above oxide.

14. The glass _{_{substrate, Sn0 2, Zr0 2, Ti0}} 2, ZnO, Ca_〇, Mg ◦, 1 or in terms of each of the Sani匕物of N i 0 and V ₂ 0 ₅ or two or more 14. The magnetic disk according to claim 12, wherein the magnetic disk is composed of an oxidized product containing 20 mol% or less in total.

15. A magnetic disk having an information recording medium substrate having an information recording thin film formed on a glass substrate surface via a layer containing cobalt oxide as a main component, wherein the information recording medium substrate is formed as described in claims. 9 to: A magnetic disk comprising the information recording medium substrate according to any one of 11 to 11.

16. A disc having an information recording thin film formed on a glass substrate surface, the information An information recording / reproducing apparatus having a recording / reproducing head for recording or reproducing data and a spindle motor for rotating the disk, wherein the glass substrate has a Young's modulus of 90 to 13 OGPa and 500 g. An information recording / reproducing apparatus characterized in that a crack occurrence rate at the time of measuring the hardness of a picker under a load of 15 seconds is 50% or less.

17. A disc provided with an information recording thin film formed on a surface of a glass substrate, a recording / reproducing head for recording or reproducing the information, and a spindle motor for rotating the disc, the information recording / reproducing apparatus comprising: An information recording / reproducing apparatus, wherein the disc comprises the information recording medium substrate according to any one of claims 9 to 11.

18. A magnetic disk provided with a magnetic thin film formed on a glass substrate surface via a layer mainly composed of cobalt oxide, a magnetic head for recording or reproducing information, and a spindle motor for rotating the magnetic disk In a magnetic disk drive equipped with a glass substrate, the glass substrate has a Young's modulus of 90 to 13 OGPa and a crack generation rate of 500 g under a load of 150 seconds when measuring Beakers hardness by 50 seconds. % Or less.

19. A magnetic disk provided with a magnetic thin film formed on a glass substrate surface via a layer mainly composed of cobalt oxide, a magnetic head for recording or reproducing information, and rotating the magnetic disk in a magnetic disk apparatus having a spindle motor evening, before Symbol glass substrate molar ratio, in terms of S I_〇 ₂ 4 0-8 0%, in terms of a 1 ₂ 0 ₃ 5 to 3 0%, in terms of N a ₂ 0 8 to 2 0% and C s ₂ 0 to 2 0% in terms of 0, M ₂ O ₃ (M is ΙΠΑ group element) containing 0-3 0% in terms of A magnetic disk drive comprising an acid ridden object.

20. A magnetic disk provided with a magnetic thin film formed on a glass substrate surface via a layer mainly composed of cobalt oxide, a magnetic head for recording or reproducing information, and rotating the magnetic disk A magnetic disk drive provided with a spindle motor, wherein the disk comprises the information recording medium substrate according to any one of claims 9 to 11.

2 1. A layer mainly composed of cobalt oxide is placed on a glass surface with a diameter of 2 or 5 inches. A magnetic disk comprising an information recording thin film formed through the magnetic disk, a magnetic head for recording or reproducing information, and a spindle motor for rotating the magnetic disk at 600 rpm or more. Wherein the glass substrate has a Young's modulus of 90 to 130 GPa and a crack generation rate of 50% or less when measuring Beakers hardness under a load of 150 seconds with a load of 50,000. Disk device.