Abstract: The present invention provides a substrate for a magnetic recording medium in which bulges are not easily formed on a surface thereof by a physical impact in a size for a 2.5-inch type hard disk drive, and a width of displacement caused by fluttering is small. The substrate for a magnetic recording medium includes an Al alloy substrate and a Ni alloy plating film formed on a surface of the Al alloy substrate, has a diameter of 54 to 70 mm, and a disk shape having a hole whose inner diameter ranges from 19 to 26 mm in the center thereof. The Al alloy substrate has a Young's modulus (E) of 74 GPa or more, a density (?) of 2.75 g/cm3 or less, and a ratio (E/?) of 27 or more between the Young's modulus (E) and the density (?). The Ni alloy plating film has a thickness of 4 to 7 ?m, and when an indentation is formed by pressing a diamond indentor whose tip has a square pyramid shape against a surface of the Ni alloy plating film with a test force of 0.

Abstract: What is provided is an aluminum alloy substrate for a magnetic recording medium which has high rigidity and an excellent plating properties. The aluminum alloy substrate for a magnetic recording medium has a constitution in which coarse grains whose average grain size is within a range that exceeds 2 ?m and is less than or equal to 20 ?m are dispersed, the average number of coarse grains per area of 0.042 mm2 is 100 or more, and a surface roughness Ra is less than or equal to 0.2 ?m.

Abstract: The present invention provides a substrate for a magnetic recording medium in which bulges are hardly formed on a surface thereof by a physical impact in a size for a 3.5-inch type HDD, and a width of displacement caused by fluttering is small. The substrate for a magnetic recording medium includes an Al alloy substrate and a Ni alloy plating film formed on a surface of the Al alloy substrate, and has a diameter of 95 to 98 mm, a disk shape having a hole whose inner diameter ranges from 19 to 26 mm in the center thereof, a thickness of 0.48 to 0.64 mm, and a mass of 9.0 to 15.0 g. The Al alloy substrate has a Young's modulus (E) of 74 GPa or more, a density (?) of 2.75 g/cm3 or less, and a ratio (E/?) of 27 or more between the Young's modulus (E) and the density (?). The Ni alloy plating film has a thickness of 4 to 7 ?m, and when an indentation is formed by pressing a diamond indentor whose tip has a square pyramid shape against a surfaces of the Ni alloy plating film with a test force of 0.

Abstract: There is provided a method of polishing the inner peripheral end surfaces of disk-like substrates for a recording medium using a brush comprising, providing a plurality of pieces of disk-like substrates having circular holes at the central portion thereof; bringing a polishing material slurry containing a polishing material into contact with the object to be polished; inserting a polishing brush into the circular hole of the object from a first side of the object to be polished, and rotating the polishing brush with the shaft as a center to polish the inner peripheral end surfaces of the substrates; and inserting the polishing brush into the circular hole of the object to be polished from a second side opposite to the first side and rotating the polishing brush with the shaft as a center axis to polish the inner peripheral end surfaces of the substrates.

Abstract: The present invention provides a low-cost polishing slurry having excellent effect with respect to defects and smoothness of the surface to be polished. The polishing slurry comprises a silica abrasive and a ceria abrasive, wherein the silica abrasive content is less than 3 mass % and the ceria abrasive content is less than 1 mass %, based on the entire polishing slurry. Further, the present invention provides a method for producing a crystallized glass substrate for an information recording medium, wherein the method use a polishing slurry of the present invention. Furthermore, the present invention provides a method for producing an information recording medium, comprising forming a recording layer on a crystallized glass substrate for an information recording medium obtained by the present method.

Abstract: The present invention provides a method for forming a carbon protective film and a method for producing a magnetic recording medium, that decreases the generation of particles in a plasma CVD apparatus thereby improving flatness of the surface of a carbon protective film, and also can manufacture a magnetic recording medium having high recording density and excellent recording/reproducing characteristics; a magnetic recording medium; and a magnetic recording/reproducing apparatus using the magnetic recording medium.

Abstract: The present invention relates to a magnetic disk substrate, in which an amplitude Wa of a waviness on a surface measured by using an interferometer for a versatile disk at a measuring wave-length of 5.0 mm is within the range of 0.1 nm to 0.5 nm, an average amplitude Wb of a microwaviness generated on the waviness measured by using a microscopy for three-dimensional surface-structural analysis at a measuring wave-length of 30 ?m to 200 ?m is 0.3 nm or less, and a value calculated by dividing the average amplitude Wb of the microwaviness by the amplitude Wa of the waviness is 0.6 or more.

Abstract: A process for manufacturing a glass substrate for a magnetic recording medium comprising polishing a crystallized glass substrate using abrasive grains, and then washing the substrate using an aqueous organic carboxylic acid solution; a glass substrate for a magnetic recording medium which is manufactured by the process; and a magnetic recording medium obtained using the substrate. A glass substrate for a magnetic recording medium is manufactured, whereby the surface roughness is low and the surface defects are minimal for washing after polishing of a crystallized glass substrate, and wherein the Read-Write performance are not impaired when a recording layer including a magnetic film is formed on the magnetic recording medium substrate for manufacturing a magnetic recording medium.

Abstract: The invention provides a magnetic disk glass substrate capable of preventing the occurrence of dust and adhesion of particles to the magnetic disk surface during a magnetic disk production process, a production method and a magnetic disk. A glass substrate for a magnetic disk has a construction in which an outer peripheral edge shape formed around a peripheral edge portion of a main surface has, with another flat portion of the main surface being the reference: an outer peripheral edge portion ski jump value of not greater than 0 ?m; an outer peripheral edge portion roll-off value of ?0.2 to 0.0 ?m; and an outer peripheral edge portion dub-off value of 0 to 120 ?; and the glass substrate has a chamfer surface between the main surface (data surface) and the outer peripheral edge surface (straight surface), and has an R surface having a radius of curvature of 0.013 to 0.080 mm between the data surface and the chamfer surface of the glass substrate.

Abstract: To provide a substrate which is not substantially chipped or cracked on the substrate end faces even when the substrate is a silicon substrate made of a brittle material, and provide a substrate which prevents dust raising from the substrate end faces and prevents dust raising due to rubbing with a processing cassette. A silicon substrate for a magnetic recording medium is formed by setting the lengths L of chamfered portions between the main surfaces of the substrate and the outer circumferential side end face to 0.1±0.03 mm and setting the angles ? between the main surfaces and the chamfered portions between the main surfaces and the outer circumferential side end face to 45 degrees ±5 degrees. It is also possible for a curved portion with a radius of 0.01 mm or more and less than 0.3 mm is interposed between the main surfaces and the outer circumferential side chamfered portions of the substrate.

Abstract: The present invention relates to a magnetic disk substrate, in which an amplitude Wa of a waviness on a surface measured by using an interferometer for a versatile disk at a measuring wave-length of 5.0 mm is within the range of 0.1 nm to 0.5 nm, an average amplitude Wb of a microwaviness generated on the waviness measured by using a microscopy for three-dimensional surface-structural analysis at a measuring wave-length of 30 ?m to 200 ?m is 0.3 nm or less, and a value calculated by dividing the average amplitude Wb of the microwaviness by the amplitude Wa of the waviness is 0.6 or more.

Abstract: A glass substrate for a magnetic recording medium, having a chamfer face between the surface of the substrate for forming thereon a film comprising a magnetic layer, and the outer peripheral end face (straight face) of the substrate, wherein an R face having a curvature of 0.013 to 0.080 mm is provided between the data face and the chamfer face of the glass substrate.

Abstract: A silicon substrate for a magnetic recording medium in which the substrate has a chamfered surface between its data-carrying surface (surface) having layers including a magnetic layer and its outer peripheral end surface (straight surface) is provided. The silicon substrate is characterized in that a dub-off value at an outer peripheral side of the data-carrying surface is not more than 120 ? wherein when a first position (A) is a point on the data-carrying surface radially and inwardly positioned at 1 mm from the outer peripheral end surface of the substrate, a second position (B) is a point on the data-carrying surface radially and inwardly positioned further at 1.

Abstract: The invention can provide a production method for a magnetic disk substrate capable of reducing the number of surface defects of a glass substrate. When a magnetic disk is produced by using the resulting magnetic disk substrate, the yield and, furthermore, the reliability can be improved. When a surface of a magnetic disk substrate is washed after it is polished, the glass substrate is dipped into a washing solution while the surface of the glass substrate polished is held under a wet condition. The wet condition of the surface of the glass substrate includes a condition in which the glass substrate is dipped into water that may contain a surfactant, and a condition in which a liquid film is formed substantially on the entire surface.

Abstract: The object of present invention is to provide a magnetic disk substrate which uses a silicon substrate, in which chamfered surfaces are provided between the main surfaces of the silicon substrate and the outer circumferential surface; a ski-jump value H0 where H0?0 ?m, representing the distance from the basal level to point A3; a roll-off value H1 where H1??0.2 ?m and H1?0.0 ?m, representing the distance from the basal level to point A1; a tag-off value H2 where H2?0 ?m and H2?0.012 ?m, representing the maximum displacement of the border line of the main surface with respect to the line A1 to A2; curved surfaces are provided between the main surfaces and the chamfered surfaces; and the curvature radius R of the curved surface where R?0.013 mm and R?0.080 mm.

Abstract: A process scheduling apparatus has a delayed task handling process for processing delayed tasks having variable priorities and multiple other processes for handling processes other than delayed tasks. Fixed priorities are assigned to the other processes. The process scheduler sequentially executes the delayed task handling process and the other processes according the assigned priorities. A delayed task registration processor stores newly generated delayed tasks with assigned priorities in a queuing table. A delayed task priority controller selects the delayed task with the highest priority in the queuing table. A process priority controller sets the priority of the delayed task handling process to the same priority as the priority of the delayed task with the highest priority.

Abstract: A glass substrate for a magnetic recording medium, having a chamfer face between the surface (data face) of the substrate for forming thereon a film comprising a magnetic layer, and the outer peripheral end face (straight face) of the substrate, wherein the outer peripheral chamfer face has a dub-off of 120 ? or less in the radial direction.

Abstract: The present invention provides a method for forming a carbon protective film and a method for producing a magnetic recording medium, that decreases the generation of particles in a plasma CVD apparatus thereby improving flatness of the surface of a carbon protective film, and also can manufacture a magnetic recording medium having high recording density and excellent recording/reproducing characteristics; a magnetic recording medium; and a magnetic recording/reproducing apparatus using the magnetic recording medium.