Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: Provided are a magnetic disk substrate and a method of manufacturing the same, wherein the magnetic disk substrate has very few defects present on its surface with an arithmetic mean roughness (Ra) at a level in the vicinity of 0.1 nm and thus is suitable as a substrate for a magnetic disk with high recording density. The magnetic disk glass substrate is such that the arithmetic mean roughness (Ra) of the main surface of the glass substrate measured using an atomic force microscope with a resolution of 256×256 pixels in a 2 ?m×2 ?m square is 0.12 nm or less and the number of defects detected to have a size of 0.1 ?m to 0.6 ?m in plan view and a depth of 0.5 nm to 2 nm is less than 10 per 24 cm2, wherein the defects are each detected using a shift in wavelength between incident light and reflected light upon irradiating and scanning helium neon laser light with a wavelength of 632 nm on the main surface of the glass substrate.

Abstract: The present invention provides a method for efficiently manufacturing a glass substrate for magnetic disk having good accuracy of a surface irregularity and an impact resistance. The method includes the steps of: performing press forming to molten glass to prepare a sheet glass material, the sheet glass material having a roughness of the principal surface of 0.01 ?m or less and target flatness of a glass substrate for magnetic disk; chemically strengthening the sheet glass material by dipping the sheet glass material in a chemically strengthening salt, thereby preparing a disk substrate; polishing the principal surfaces of the disk substrate. A thickness of the sheet glass material prepared in the press forming step is larger than a target thickness of the glass substrate for magnetic disk by a polishing quantity of the principal surface polishing step.

Abstract: The shape and number of surface defects are controlled so that the occurrence of failure is suppressed in an HDD device in which a magnetic head with a very small flying height, such as a DFH head, is mounted. A magnetic disk substrate is characterized in that when laser light with a wavelength of 405 nm and a laser power of 25 mW is irradiated with a spot size of 5 ?m and scattered light from the substrate is detected, the number of defects detected to have a size of 0.1 ?m to not more than 0.3 ?m is less than 50 per 24 cm2 and, with respect to the defects, there is no defect in which, in a bearing curve obtained by a bearing curve plot method using an atomic force microscope, a portion from an apex of the defect to 45% thereof is located in an area of defect height higher than a virtual line connecting from the apex of the defect to 45% thereof.

Abstract: Provided are a magnetic disk substrate that can be adapted to a reduction in flying height of a head in an HDD and to an increase in rotational speed therein, and a method of manufacturing such a substrate. In an annular glass substrate for a magnetic recording medium, a main surface (12) of the glass substrate is uniformly inclined from an inner peripheral end (13) to an outer peripheral end (14) and has an isotropic shape with respect to an axis passing through the center of the glass substrate. That is, it is rotationally symmetric with respect to an arbitrary angle rotation about the axis passing through the center of the glass substrate.

Abstract: A glass substrate for information recording medium, said glass substrate being composed of an alminosilicate glass containing 60-75% by mass of SiO2, 5-18% by mass of Al2O3, 3-10% by mass of Li2O, 3-15% by mass of Na2O and 0.5-8% by mass of ZrO2 relative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one polyvalent element selected from the group consisting of V (vanadium), Mn (manganese), Ni (nickel), Nb (niobium), Mo (molybdenum), Sn (tin), Ce (cerium), Ta (tantalum) and Bi (bismuth). The molar ratio of the total amount of the polyvalent elements to the amount of ZrO2 is within the range of 0.05-0.50.

Abstract: A glass substrate for information recording medium, said glass substrate being composed of an aluminosilicate glass containing 60-75% by mass of SiO2, 5-18% by mass of Al2O3, 3-10% by mass of Li2O, 3-15% by mass of Na2O and 0.5-8% by mass of ZrO2 relative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one substance selected from the group consisting of SO3 (sulfurous acid), F (fluorine), Cl (chlorine), Br (bromine) and I (iodine), as a refining agent. The molar ratio of the total amount of the refining agent to the amount of ZrO2 is within the range of 0.05-0.50.

Abstract: The present invention relates to a process for producing a base material for disks of disk rolls, in which the disk roll contains a rotating shaft and a plurality of the disks fitted on the rotating shaft by insertion whereby the outer peripheral surface of the disks serves as a conveying surface, in which the process contains molding a slurry raw material containing inorganic fibers, an inorganic filler having an aspect ratio of from 1 to 25 and an inorganic binder into a plate shape; and drying the molded plate.

Abstract: The present invention provides a base material for disk rolls which is a platy molded article for obtaining ring-shaped disks for use in a disk roll comprising a rotating shaft and ring-shaped disks fitted thereon by insertion, whereby the peripheral surface of the disks serves as a conveying surface, the base material comprising inorganic fibers having a crystallization temperature of 800-900° C., a filler, and a clay. Also disclosed is a disk roll which comprises disks cut out of the base material.

Abstract: Embodiments of a process comprising forming one or more micro-electro-mechanical (MEMS) probe on a conductive metal oxide semiconductor (CMOS) wafer, wherein each MEMS probe comprises a cantilever beam with a fixed end and a free end and wherein the CMOS wafer has circuitry thereon; forming an unsharpened tip at or near the free end of each cantilever beam; depositing a silicide-forming material over the tip; annealing the wafer to sharpen the tip; and exposing the sharpened tip.

Abstract: A method and apparatus for planarizing magnetically susceptible layers of substrates is provided. A patterned resist is formed on the magnetically susceptible layer, and the substrate is subjected to a plasma immersion ion implantation process to change a magnetic property of the magnetically susceptible layer according to the pattern of the resist material. The substrate is subjected to a plasma material removal process either before or after the implantation process to planarize the surface of the magnetically susceptible layer resulting from the implantation process. The plasma material removal process may be directional or non-directional.

Abstract: A method of manufacturing a disk for a magnetic storage device is provided. The method comprises electroless plating a coating layer over a substrate to produce the disk, the coating layer forming an exterior surface of coating over the substrate, and annealing the coating layer using a heating source, wherein heat radiating from the heating source is directionally focused onto the exterior surface before the exterior surface is polished.

Abstract: An aspect of the present invention relates to a glass substrate for a magnetic recording medium, which is comprised of glass with a glass transition temperature of equal to or greater than 600° C., an average coefficient of linear expansion at 100 to 300° C. of equal to or greater than 70×10?7/° C., a Young's modulus of equal to or greater than 81 GPa, a specific modulus of elasticity of equal to or greater than 30 MNm/kg, and a fracture toughness value of equal to or greater than 0.9 MPa·m1/2.

Abstract: A glass substrate for information recording medium, said glass substrate being composed of an aluminosilicate glass containing 60-75% by mass of SiO2, 5-18% by mass of Al2O3, 3-10% by mass of Li2O, 3-15% by mass of Na2O and 0.5-8% by mass of ZrO2 relative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one substance selected from the group consisting of SO3 (sulfurous acid), F (fluorine), Cl (chlorine), Br (bromine) and I (iodine), as a refining agent. The molar ratio of the total amount of the refining agent to the amount of Al2O3 is within the range of 0.02-0.20.

Abstract: A magnetic tape produced by cutting a magnetic sheet with a wide breadth into a tape having a predetermined width using a cutting device, in which the magnetic sheet has a magnetic layer containing magnetic powder and a hinder formed on one surface of a non-magnetic substrate having a thickness of 4 ?m or less, and a center line average height (Ra) along a roughness curve of a cut edge of the magnetic tape is from 0.08 to 0.25 ?m.

Abstract: A glass substrate for a magnetic disk, wherein, in regions with respect to two places arbitrarily selected on a surface of the glass substrate on its central portion side relative to its outer peripheral end, a surface shape with a shape wavelength in a band of 60 to 500 ?m is extracted from surface shapes in each of the regions and, assuming that a root mean square roughness Rq of the surface shape is given as a microwaviness Rq, the difference between the microwavinesses Rq of the regions is 0.02 nm or less or the difference between standard deviations of the microwavinesses Rq of the regions is 0.04 nm or less.

Abstract: [Problem to be solved] To provide a biaxially oriented polyester film, which suffers only small dimensional changes due to changes in environmental temperature and humidity and due to storage, ensures low error rates, and can little abrade the magnetic head and the magnetic tape, when used as a base film of a magnetic recording medium, and which can be used to provide a high density magnetic recording medium excellent in running durability. [Solution] A biaxially oriented polyester film having an islands-in-sea structure, an average island domain size of 30 to 200 nm, and a coefficient of hygroscopic expansion of 0 to 6.0 ppm/% RH at least either in the machine direction or in the transverse direction of the film.

Abstract: An aspect of the present invention relates to glass for a magnetic recording medium substrate, which comprises, denoted as molar percentages, 50 to 75 percent of SiO2, 0 to 5 percent of Al2O3, 0 to 3 percent of Li2O, 0 to 5 percent of ZnO, a total of Na2O and K2O of 3 to 15 percent, a total of MgO, CaO, SrO, and BaO of 14 to 35 percent, a total of ZrO2, TiO2, La2O3, Y2O3, Yb2O3, Ta2O5, Nb2O5, and HfO2 of 2 to 9 percent, with a molar ratio of {(MgO+CaO)/(MgO+CaO+SrO+BaO)} falling within a range of 0.85 to 1, and a molar ratio of {Al2O3/(MgO+CaO)} falling within a range of 0 to 0.30.

Abstract: The present invention provides a base material for disk rolls which is a platy molded article for obtaining ring-shaped disks for use in a disk roll comprising a rotating shaft and ring-shaped disks fitted thereon by insertion, whereby the peripheral surface of the disks serves as a conveying surface, the base material comprising inorganic fibers having a crystallization temperature of 800-900° C., a filler, and a clay. Also disclosed is a disk roll which comprises disks cut out of the base material.

Abstract: To provide glass to be used for a substrate which is, as a substrate, less susceptible to surface roughening even if subjected to cleaning by means of a strongly acidic solution. Glass for a substrate, which comprises, as represented by mol % based on the following oxides, from 62.5 to 69% of SiO2, from 9 to 15.5% of Al2O3, from 8 to 16 of Li2O, from 0 to 8% of Na2O, from 0 to 7% of K2O and from 0 to 3.5% of ZrO2, provided that SiO2—Al2O3 is at least 53.3%, Li2O+Na2O+K2O is from 17 to 24%, and the total of contents of the above six components is at least 97%.