Glass substrate for information recording media and information recording medium

Abstract

A glass substrate for information recording media in which the ratio (Rab / Raf) of the center line average height Raf of the surface of when the substrate is held in water at 80 DEG C for 24 hours to the center line average height Rab before it is held in water as above described is 0.8 to 1, and the Young's modulus is 90 GPa or more. An information recording medium having an information recording layer on such a glass substrate is also disclosed.

Description

technical field

[0001] The present invention relates to a glass substrate for an information recording medium and an information recording medium. In more detail, the present invention relates to a glass substrate having a high Young's modulus, high rigidity, and particularly suitable as a substrate for an information recording medium requiring excellent surface smoothness as well as a high modulus of elasticity and a high expansion rate, and An information recording medium including the glass substrate. Background technique

[0002] The main components of a magnetic storage device such as a computer are a magnetic recording medium and a magnetic head for magnetic recording and reproducing. As the former magnetic recording medium, a flexible disk and a hard disk are known. Among them, aluminum alloys are mainly used as substrate materials for hard disks. Recently, with the downsizing of hard disk drives and higher density of magnetic recording, the floating amount of the ...

Examples

Embodiment 1-11 and comparative example 1

[0055] As a starting material, SiO 2 、Al 2 o 3 , Al(OH) 3 , MgO, Mg(OH) 2 , MgCO 3 , CaCO 3 , Li 2 CO 3 、Na 2 CO 3 、TiO 2 and ZrO 2 etc., in order to obtain the glass with the composition shown in Table 1 and Table 2, weigh 300-1500g, mix thoroughly to make a blended batch, put it into a platinum crucible, and conduct glass in air at a temperature of 1400-1600°C. The melting takes about 3-8 hours. After melting, let the molten glass flow into a 40×40×20mm carbon mold, let it cool to the transition point temperature of the glass, put it into the annealing furnace immediately, keep it for 1 hour, and then cool it naturally in the furnace to room temperature. The resulting glass did not precipitate microscopically observable crystals.

[0056] The glass thus obtained was processed into 40×20×15 mm, 5Φ×20 mm, and 30×30×2 mm to prepare samples for evaluation of various physical properties, and each physical property was measured by the method shown below.

[0057] Tab...

technical field

[0001] The present invention relates to a glass substrate for an information recording medium and an information recording medium. In more detail, the present invention relates to a glass substrate having a high Young's modulus, high rigidity, and particularly suitable as a substrate for an information recording medium requiring excellent surface smoothness as well as a high modulus of elasticity and a high expansion rate, and An information recording medium including the glass substrate. Background technique

[0002] The main components of a magnetic storage device such as a computer are a magnetic recording medium and a magnetic head for magnetic recording and reproducing. As the former magnetic recording medium, a flexible disk and a hard disk are known. Among them, aluminum alloys are mainly used as substrate materials for hard disks. Recently, with the downsizing of hard disk drives and higher density of magnetic recording, the floating amount of the ...

Examples

Embodiment 1-11 and comparative example 1

[0055] As a starting material, SiO 2 、Al 2 o 3 , Al(OH) 3 , MgO, Mg(OH) 2 , MgCO 3 , CaCO 3 , Li 2 CO 3 、Na 2 CO 3 、TiO 2 and ZrO 2 etc., in order to obtain the glass with the composition shown in Table 1 and Table 2, weigh 300-1500g, mix thoroughly to make a blended batch, put it into a platinum crucible, and conduct glass in air at a temperature of 1400-1600°C. The melting takes about 3-8 hours. After melting, let the molten glass flow into a 40×40×20mm carbon mold, let it cool to the transition point temperature of the glass, put it into the annealing furnace immediately, keep it for 1 hour, and then cool it naturally in the furnace to room temperature. The resulting glass did not precipitate microscopically observable crystals.

[0056] The glass thus obtained was processed into 40×20×15 mm, 5Φ×20 mm, and 30×30×2 mm to prepare samples for evaluation of various physical properties, and each physical property was measured by the method shown below.

[0057] Tab...