Kabushiki Kaisha Ohara

Ohara, Inc.

Kabushiki Kaisya Ohara

Naoyuki Goto

Toshitaka Yagi

Katsuhiko Yamaguchi

Junko Ishioka

Yutaka Yamashita

Yasuyuki Kawashima

Kousuke Nakajima

Kohei Ogasawara

Yuki Motoshima

Reika Kojima

Mariko Kataoka

Takayuki Kishi

Donald G Polensky

Kazuo Ohara

Satoru Matsumoto

Hisao Yatsuda

Hiroyuki Minamikawa

Futoshi Ishizaki

Ayako Shindo

Kazuo {overscore (O)}hara

Moriji Nozaki

Kiyoyuki Momono

Goro Enomoto

Masashi Maekawa

Hideo Yasui

Kazuhiro Itoh

Ayako Yamaguchi

A method for manufacturing a crystallized glass member having a curved shape includes a deforming step of deforming at least a portion of a glass plate into a curved shape by an external force that acts on the glass plate while maintaining the temperature of the glass plate within a first temperature range and precipitating crystals from the glass plate. In the method for manufacturing a crystallized glass member having a curved shape according to Claim, the first temperature range is from [At−40]° C. to [At+40]° C., wherein At (° C.) is a yield point of the glass plate.

Method for manufacturing crystallized glass member having curved shape

To provide a crystallized glass substrate including a surface with a compressive stress layer, in which, CS is 400 to 1400 MPa and CT×(T−2×DOL)/CS×DOLis 0.60 or more, where CS (MPa) denotes a compressive stress on an outermost surface of the compressive stress layer, DOL(μm) denotes a stress depth of the compressive stress layer at which the compressive stress is 0 MPa, CT (MPa) denotes a central stress determined by curve analysis, and T (μm) denotes a thickness of the substrate.

Crystallized glass substrate

To provide a crystallized glass substrate including a surface with a compressive stress layer, in which a stress depth DOLof the compressive stress layer, at which the compressive stress is 0 MPa, is 45 to 200 μm, a compressive stress CS on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and CS×DOL, which is a product of the compressive stress CS on the outermost surface and the stress depth DOL(μm), is 4.8×10or more.

To provide a crystallized glass substrate including a surface with a compressive stress layer, where a stress depth DOLof the compressive stress layer, at which the compressive stress is 0 MPa, is 45 to 200 μm, a compressive stress CS on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and a central stress CT determined by using curve analysis is 55 to 300 MPa.

To provide a crystallized glass substrate including a surface with a compressive stress layer, in which a compressive stress CS (MPa) on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and DOL/DOLis 0.30 or more, where DOL(μm) is a depth at which the value of the compressive stress is 50% of the CS and DOL(μm) is a depth at which the value of the compressive stress is 0 MPa.

To provide a crystallized glass substrate including a surface with a compressive stress layer, in which a stress depth DOLof the compressive stress layer, at which the compressive stress is 0 MPa, is 45 to 200 &#x3bc;m, a compressive stress CS on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and CS&#xd7;DOL, which is a product of the compressive stress CS on the outermost surface and the stress depth DOL(&#x3bc;m), is 4.8&#xd7;10or more.

To provide a crystallized glass substrate including a surface with a compressive stress layer, where a stress depth DOLof the compressive stress layer, at which the compressive stress is 0 MPa, is 45 to 200 &#x3bc;m, a compressive stress CS on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and a central stress CT determined by using curve analysis is 55 to 300 MPa.

A crystallized glass includes a crystallized glass mother material, and, in a surface, a compressive stress layer, wherein the crystallized glass has, for a thickness of 10 mm, a light transmittance of, including reflection loss, 80% at a wavelength in 400 to 669 nm, and has a Vickers hardness [Hv] of 835 to 1300. In the crystallized glass, the crystallized glass mother material contains, in % by weight on an oxide basis, 40.0% to 70.0% of a SiOcomponent, 11.0% to 25.0% of an AlOcomponent, 5.0% to 19.0% of a NaO component, 0% to 9.0% of a KO component, 1.0% to 18.0% of a MgO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiOcomponent, and a total content of the SiOcomponent, the AlOcomponent, the NaO component, the KO component, the MgO component, and the TiOcomponent is 90% or more.

Crystallized glass

To provide a crystallized glass substrate that is hard and resistant to fracture and that is also resistant to shattering upon breakage. A crystallized glass substrate includes a crystallized glass serving as a base material and a compressive stress layer forming a surface thereof. The crystallized glass contains, in % by weight on an oxide basis, 40.0% to 70.0% of a SiOcomponent, 11.0% to 25.0% of an AlOcomponent, 5.0% to 19.0% of a NaO component, 0% to 9.0% of a KO component, 1.0% to 18.0% of one or more selected from a MgO component and a ZnO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiOcomponent. The SiOcomponent, the AlOcomponent, the NaO component, the one or more selected from the MgO component and the ZnO component, and the TiOcomponent are present in a total amount of 90% or more. The compressive stress layer has a depth of layer of 40 &#x3bc;m or more. The compressive stress layer has a surface compressive stress of 750 MPa or more. The compressive stress layer has a central tension of 65 MPa or less as determined by curve analysis.

It is an object of the present invention to provide a crystallized glass which has various properties required for employing the substrate for information recording medium of the next generation, and also has significantly low specific gravity; and a crystallized glass substrate for information recording medium. A crystallized glass containing, as a crystal phase, one or more selected from RAlOand RTiO(wherein R is one or more selected from Mg and Fe), the crystallized glass comprising the components of SiOof 50% to 70%, AlOof 10% to 26%, TiOof 1 to 15%, MgO of 2.5% to 25%, FeO of 0% to 8%, and ZnO of 0% to less than 2%, expressed in terms of mass percentage on an oxide basis, wherein the value of (AlO+MgO)/SiOis 0.30 or more and 0.65 or less, and a specific gravity is less than 2.63.

Crystallized glass and crystallized glass substrate for information recording medium

To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAlOand RTiOas a main crystal phase, in which R is one or more selected from Zn, Mg and Fe, and in which the main crystal phase has a crystal grain size in a range of from 0.5 nm to 20 nm, a degree of crystallinity of 15% or less, and a specific gravity of 3.00 or less.

Crystallized glass substrate for information recording medium and method of producing the same

A manufacturing method is provided for manufacturing a substrate for information storage media having various properties that are demanded for a next generation of information storage media substrate purposes exemplified by perpendicular magnetic recording systems, etc., and above all, having high fracture toughness and a smooth surface at low cost. The method of manufacturing a substrate for information storage media includes a step of preparing glass material of a plate shape containing SiOcomponent, AlOcomponent, and R'O component, R&#x2032; being at least one selected from Li, Na, and K, and the step of lapping includes at least one sub-step of lapping the glass material with a diamond pad.

Method of manufacturing substrate for information storage media

There is provided a glass substrate which has the properties required in the use as a substrate for an information recording medium of the next generation such as a perpendicular magnetic recording system, and can be applied as a substrate for an information recording medium of the next generation particularly on the premise of using the glass substrate in a dynamic environment. More particularly, there is provided a glass substrate for an information recording medium which has sufficiently high surface hardness, has a good balance between specific gravity and mechanical strength, and has high strength to withstand high speed rotation or drop impact, and which can be produced with a high productivity adequate for a direct press method, without the occurrence of bubbles in the glass blank or reboil upon pressing even if arsenic components or antimony components are not substantially used. A glass substrate for an information recording medium, includes, as expressed in terms of percent by mass on the oxide basis: 52 to 67% of SiO, 3 to 15% of AlO, and 0.2 to 8% of PO, the glass substrate having a Young's modulus of 85 GPa or greater, a specific gravity of 2.60 or less, and a ratio of Young's modulus to specific gravity (Young's modulus/specific gravity) of 33.0 or greater.

Glass substrate for information recording medium and method for producing the same

For providing glass-ceramics having properties suitable for use as a substrate of an information storage medium of next generation such as one for the perpendicular magnetic recording system without employing arsenic and antimony components which adversely affect human beings and the environment, there are provided glass-ceramics comprising SiO, LiO and AlOon oxide basis, comprising lithium disilicate as a crystal phase, and comprising one or more elements selected from the group consisting of Sn, Ce, Mn, W, Ta, Bi, Nb, S, Cl and F.

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Machida, Japan

Naoyuki Goto