Abstract: Provided is a magnetic recording medium glass substrate manufacturing method capable of manufacturing a magnetic recording medium glass substrate having high surface smoothness and low surface waviness with productivity. In a primary lapping process and a secondary lapping process of the manufacturing method, diamond pads (20A and 20B) in which diamond abrasive grains are fixed by a binder are used. A plurality of convex portions (21) with a flat top are arranged in a tile shape on a lapping surface (20a) of each of the diamond pads (20A and 20B). In the diamond pad (20A) used in the primary lapping process, the average diameter of the diamond abrasive grains is in the range of 4 ?m to 12 ?m and the content of the diamond abrasive grains in the convex portion (20A) is in the range of 5 vol % to 70 vol %.

Abstract: The object of the present invention is to provide a production method for a glass substrate having a sufficient impact resistance for a magnetic recording medium with high productivity, without using cerium oxide, or by decreasing the amount of cerium oxide used in the polishing step, and the present invention provides a method for producing a glass substrate for a magnetic recording medium including at least a grinding step for inner and outer peripheries of a disc-shaped glass substrate having a center hole, wherein the grinding step includes a first grinding step for inner and outer peripheries of the glass substrate using a metal-bonded diamond grinding stone in which diamond abrasive grains are fixed with a metal binder, and a second grinding step for the inner and outer peripheries of the glass substrate using a resin-bonded diamond grinding stone in which diamond abrasive grains are fixed with a resin binder.

Abstract: The polishing method of a disk-shaped substrate for polishing an outer circumference 13 of a disk-shaped substrate using slurry is provided with in this sequence: a first polishing process for polishing the outer circumference 13 using an abrasive-grain inclusion brush 50 made of a resin in which polishing abrasive grains are included; and a second polishing process for polishing the outer circumference 13 using a resin brush 60 made of a resin in which the polishing abrasive grains are not included.

Abstract: A method of manufacturing a glass substrate for a magnetic recording medium, wherein inner and outer circumference end faces of a disk-like glass substrate having a central aperture are at least treated by: a step of grinding, a step of etching, and a step of polishing, wherein the steps are performed in this order.

Abstract: The invention provides a method of manufacturing a glass substrate for magnetic recording media. And the glass substrate has high surface smoothness and little waviness. In the primary, secondary and tertiary lapping process, diamond pads 20A, 20B, and 20C are used, respectively. The diamond pad 20A has an average diamond grain size of 4 to 12 ?m, and a content of diamond grains of 5 to 70% by volume. The diamond pad 20B has an average diamond grain size of 1 to 5 ?m, and a content of diamond grains of 5 to 80% by volume. The diamond pad 20C has an average diamond grain size of 0.2 to 2 ?m, and a content of diamond grains of 5 to 80% by volume. In the polishing process, the silicon oxide is used as abrasive without using cerium oxide, and before the polishing process, an etching process is provided.

Abstract: The disk-shaped substrate manufacturing method is provided with: generating an air stream downward from an upper area during grinding a disk-shaped substrate in a grinding apparatus; arranging the grinding apparatus on an upper floor face of a floor and arranging water on a lower floor face of the floor, the upper floor face being made of a board having penetration holes or a mesh member, and the lower floor face supporting the upper floor face so as to be located above the lower floor face with a distance; and guiding dust made by the grinding apparatus to the water by use of the air stream.

Abstract: The invention provides a method of manufacturing a glass substrate for magnetic recording media. And the glass substrate has high surface smoothness and little waviness. In the primary, secondary and tertiary lapping process, diamond pads 20A, 20B, and 20C are used, respectively. The diamond pad 20A has an average diamond grain size of 4 to 12 ?m, and a content of diamond grains of 5 to 70% by volume. The diamond pad 20B has an average diamond grain size of 1 to 5 ?m, and a content of diamond grains of 5 to 80% by volume. The diamond pad 20C has an average diamond grain size of 0.2 to 2 ?m, and a content of diamond grains of 5 to 80% by volume. In the polishing process, the silicon oxide is used as abrasive without using cerium oxide.

Abstract: The grinding method of a disk-shaped substrate that grinds a disk-shaped substrate including a portion having a hole at the center thereof while rotating the disk-shaped substrate is provided with: grinding an inner circumference of the disk-shaped substrate while an inner circumference grinding device is fed in a radial direction toward an outer circumference of the disk-shaped substrate and grinding the outer circumference of the disk-shaped substrate while an outer circumference grinding device is fed in the radial direction toward the inner circumference of the disk-shaped substrate; and stopping the feedings of the inner circumference grinding device and the outer circumference grinding device at the same time.

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 disk-shaped substrate inner circumference polishing method for polishing an inner circumference of a disk-shaped substrate including a portion having an opening hole at the center thereof includes inserting a brush having a shaft core into the portion having the opening hole of the disk-shaped substrate; fixing one end and the other end of the brush to a pair of rotating shafts that are provided at mutually detached positions and pulling at least any one of the one end and the other end of the brush and applying tension in the axial direction to the shaft core of the brush; and rotating the brush and polishing the inner circumference of the disk-shaped substrate.

Abstract: A method of manufacturing a substrate for a magnetic recording medium that is capable of manufacturing a magnetic recording medium substrate having no warping and superior surface smoothness at a high level of productivity and at low cost. The method of manufacturing a substrate for a magnetic recording medium according to the present invention includes a thin glass sheet formation step of heating and softening a sheet-like glass base material (1), and heat-stretching the glass base material (1) while pulling the material downward through space, thereby forming a thin glass sheet (5), a glass substrate formation step of cutting a circular disc-shaped glass substrate from the thin glass sheet (5), and a surface processing step of subjecting the disc-shaped glass substrate to lapping and/or polishing surface processing.

Abstract: The polishing apparatus that polishes an inner circumferential surface of a disk-shaped substrate including a portion having a hole at the center thereof, the polishing apparatus is provided with: a rotating table that holds piled workpieces in which a plurality of disk-shaped substrates are piled, a polishing brush that is inserted into a portion having the hole of the disk-shaped substrates of the piled workpieces and is rotated, a cover member that covers the piled workpieces, and a polishing-liquid flowing-in unit that flows polishing liquid into the portion having the hole of the disk-shaped substrates of the piled workpieces covered by the cover member.

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: The object of the invention is to provide a method of polishing the end surfaces of a substrate for a recording medium, which is capable of efficiently polishing the inner peripheral end surface and/or the outer peripheral end surface of the substrate preventing the reliability of performance of the recording medium from being impaired by the adhesion of the residual polishing material. According to the invention, there is provided a method of polishing end surfaces of a substrate for a recording medium wherein an inner peripheral end surface or an outer peripheral end surface of a substrate for a disk-like recording medium having a circular hole at the central portion thereof is brought into contact with a polishing medium obtained by dispersing polishing grains in a viscoelastic resin carrier and the polishing medium flows, thereby to polish the inner peripheral end surface or the outer peripheral end surface.

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: 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: The disk-shaped substrate manufacturing method is provided with: generating an air stream downward from an upper area during grinding a disk-shaped substrate in a grinding apparatus; arranging the grinding apparatus on an upper floor face of a floor and arranging water on a lower floor face of the floor, the upper floor face being made of a board having penetration holes or a mesh member, and the lower floor face supporting the upper floor face so as to be located above the lower floor face with a distance; and guiding dust made by the grinding apparatus to the water by use of the air stream.

Abstract: The disk-shaped substrate manufacturing method is provided with: scrub-washing a first surface and a second surface of a disk-shaped substrate by respectively using a first porous roller and a second porous roller that have a cylindrical shape and are rotationally driven. The process of the scrub-washing determines a distance between axes of the first porous roller and the second porous roller that sandwich the disk-shaped substrate in between, and performs scrub-washing while the determined distance between the axes is under control.

Abstract: The polishing method of a disk-shaped substrate for polishing an outer circumference 13 of a disk-shaped substrate using slurry is provided with in this sequence: a first polishing process for polishing the outer circumference 13 using an abrasive-grain inclusion brush 50 made of a resin in which polishing abrasive grains are included; and a second polishing process for polishing the outer circumference 13 using a resin brush 60 made of a resin in which the polishing abrasive grains are not included.