Abstract: A method of producing a glass article includes holding a carrier having a circular shape, in which a glass substrate having a circular shape is retained, with an upper surface plate and a lower surface plate; and polishing the glass substrate by rotating the carrier with respect to the upper surface plate and the lower surface plate, to obtain the glass article. The glass substrate is disposed in the carrier such that, in a top plan view, a center of the carrier is included in a region of the glass substrate, and a center of the glass substrate is shifted from the center of the carrier.

Abstract: A method of producing a glass article includes holding a carrier having a circular shape, in which a glass substrate having a circular shape is retained, with an upper surface plate and a lower surface plate; and polishing the glass substrate by rotating the carrier with respect to the upper surface plate and the lower surface plate, to obtain the glass article. The glass substrate is disposed in the carrier such that, in a top plan view, a center of the carrier is included in a region of the glass substrate, and a center of the glass substrate is shifted from the center of the carrier.

Abstract: The present invention relates to a method for manufacturing a glass substrate for information recording medium, the method including: a lapping step of lapping a circular glass plate made of an alkali aluminosilicate glass; and a subsequent cerium oxide polishing step of polishing the circular glass plate with a slurry containing a cerium oxide abrasive, in which a difference (SiO2?Al2O3) obtained by subtracting an Al2O3 content from an SiO2 content in the alkali aluminosilicate glass is 62% by mole or less; and in which the method further includes: subsequently to the cerium oxide polishing step, a cleaning step of cleaning the circular glass plate with a cleaning liquid having a sulfuric acid concentration of 20% by mass or more and 80% by mass or less and a hydrogen peroxide concentration of 1% by mass or more and 10% by mass or less at a liquid temperature of 50° C. or higher and 100° C.

Abstract: The present invention relates to a method for manufacturing a disk-shaped glass substrate for a magnetic recording medium, having a circular hole at the center thereof, the method including: a shape-forming step of performing shape forming to a glass substrate having a sheet shape; a polishing step of polishing a main surface of the glass substrate; and a cleaning step of cleaning the glass substrate, in which the polishing step includes a finish polishing step of simultaneously polishing both main surfaces of the glass substrate using a polishing slurry containing abrasives having an average particle diameter of 100 nm or less; and the glass substrate polished in the finish polishing step has a thickness deviation among glass substrates polished in the same lot of 1.5 ?m or less.

Abstract: The present invention relates to a glass substrate for a magnetic recording medium, which is a disk-shaped glass substrate for a magnetic recording medium having a circular hole at the center thereof, in which the glass substrate for a magnetic recording medium has an inner peripheral side surface, an outer peripheral side surface and both main surfaces, and the both main surfaces have parallelism of 3.2 ?m or less in at least a recording and reproducing region thereof.

Abstract: The present invention relates to a method for manufacturing a glass substrate for information recording medium, the method including: a lapping step of lapping a circular glass plate made of an alkali aluminosilicate glass; and a subsequent cerium oxide polishing step of polishing the circular glass plate with a slurry containing a cerium oxide abrasive, in which a difference (SiO2?Al2O3) obtained by subtracting an Al2O3 content from an SiO2 content in the alkali aluminosilicate glass is 62% by mole or less; and in which the method further includes: subsequently to the cerium oxide polishing step, a cleaning step of cleaning the circular glass plate with a cleaning liquid having a sulfuric acid concentration of 20% by mass or more and 80% by mass or less and a hydrogen peroxide concentration of 1% by mass or more and 10% by mass or less at a liquid temperature of 50° C. or higher and 100° C.

Abstract: A method for producing a magnetic disk having a surface roughness in the entire portion of its main surface in which the peak height of the surface roughness in a data zone of the magnetic disk is lower than the peak height of the surface roughness in a CSS zone of the magnetic disk, wherein forming a magnetic disk substrate having the main surface in which a surface roughness having a substantially uniform peak height is formed in the substantially entire portion of the main surface; conducting varnishing only to the data zone in the main surface of the substrate having the surface roughness to lower the peak height of the surface roughness of the data zone; and forming a ferromagnetic layer, a protective layer and a lubricant layer sequentially on a region of the main surface of the substrate, which includes the data zone and the CSS zone.