Abstract: An object of the present invention is to provide a method of manufacturing a glass substrate containing alkali metals. A glass substrate manufactured by the method exhibits excellent performances including durability by virtue of suppressing elution of alkali metals. A method comprises a step of immersing a glass material in an aqueous solution containing a formate to suppress elution of component of the glass material.

Abstract: Substrates for perpendicular magnetic recording media, and perpendicular magnetic recording media using such substrates, are disclosed. By setting the substrate inclination angle, or a parameter related to substrate shape relating to this angle, within an appropriate range, magnetic recording media can be obtained with excellent read signal quality and signal quality stability, regardless of the final substrate machining method.

Abstract: The present invention provides a method of manufacturing a glass substrate for a magnetic recording medium, the method allowing the surface roughness of the glass substrate being controlled easily and precisely in a stable state. The method comprises a step of finish polishing of polishing a surface of the glass substrate with a slurry containing two types of colloidal silica particles having different diameters and mixed in a predetermined ratio.

Abstract: Substrates for perpendicular magnetic recording media, and perpendicular magnetic recording media using such substrates, are disclosed. By setting the substrate inclination angle, or a parameter related to substrate shape relating to this angle, within an appropriate range, magnetic recording media can be obtained with excellent read signal quality and signal quality stability, regardless of the final substrate machining method.

Abstract: An object of the present invention is to provide a method of manufacturing a glass substrate containing alkali metals. A glass substrate manufactured by the method exhibits excellent performances including durability by virtue of suppressing elution of alkali metals. A method comprises a step of immersing a glass material in an aqueous solution containing a formate to suppress elution of component of the glass material.

Abstract: A molding die, intermediate member, and method of manufacturing a substrate are provided in which intrusion of air between the substrate molding material and the molding die during molding is suppressed, and release of the substrate molding material from the press molding die after the molding process is made easy even in the center of the molding die. A molding die for molding an intermediate member has a disk area molding portion which molds a disk area, and a removal area molding portion which molds a removal area, the removal area molding portion including a curved surface portion which is continuously concave. An intermediate member manufactured using the molding die has a disk area and a removal area which has a curved surface portion which is continuously convex and which becomes an aperture portion upon removal.

Abstract: A press molding die for a glass material is manufactured by forming an organic compound layer composed of an organic compound having a pyrolysis temperature on the press molding surface of the press molding die; and converting the organic compound layer into a mold release layer by heating to a temperature of at least the pyrolysis temperature of the organic compound. The mold release layer is thus inexpensively provided on the press molding surface, secures excellent releasability of a glass material from the press molding surface of the die, and does not cause unevenness of the press molding surface even upon repeatedly carrying out press molding.

Abstract: A magnetic recording medium is provided that includes a non-magnetic base, a magnetic layer laminated on a non-magnetic base, a carbon protective layer containing hydrogen and laminated on the magnetic layer, and a lubrication layer formed by applying a liquid lubricant to the carbon protective layer. The carbon protective layer includes a surface layer containing nitrogen, and the composition ratios of nitrogen and hydrogen in the surface layer may be suitably controlled to optimum ranges.