Ohara, Inc.

Yutaka Yamashita

Naoyuki Goto

Toshitaka Yagi

Kohei Ogasawara

Yuki Motoshima

Reika Kojima

Moriji Nozaki

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, 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.

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, 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, 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.

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.

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.

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Kanagawa, Japan

Yutaka Yamashita