Medium substrate, production method thereof and magnetic disk device
AssigneeFujitsu Limited
InventorKenrou Yamamoto
Life of this patent
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Abstract
A medium substrate comprising a borosilicate glass containing silica as a main component and having on the surface thereof a continuous texture derived from the porous structure, the medium substrate being used as a substrate in the production of a magnetic recording medium and other. The method for the production of the textured medium substrate is also disclosed, along with a magnetic recording medium using the medium substrate and a magnetic disk device.
Claims23
A medium substrate for use as a substrate in magnetic recording mediums and the like, said medium substrate comprising silica (SiO2) glass having a purity of 99% or more as a main component, the silica glass being a sea component of phase-separated borosilicate glass having an islands-in-sea structure, and having on the surface thereof a continuous texture derived from the porous structure of the silica glass, the texture having a surface roughness Ra of 1 to 10 nm and a pore size of 5 to 250 nm.
A method for producing a medium substrate for use as a substrate in magnetic recording mediums and the like, said medium substrate comprising silica (SiO2) glass having a purity of 99% or more as a main component, the silica glass being a sea component of phase-separated borosilicate glass having an islands-in-sea structure, and having on the surface thereof a continuous texture derived from the porous structure of the silica glass, the texture having a surface roughness Ra of 1 to 10 nm and a pore size of 5 to 250 nm,
- the method comprising the steps of:
- heat-treating a disk of borosilicate glass at a temperature of 500 to 750° C. to cause phase separation, thereby forming the phase-separated borosilicate glass;
- and
- treating the phase-separated borosilicate glass with an acid selected from the group consisting of nitric acid, sulfuric acid, hydrochloric acid and acetic acid to dissolve out an islands component from the phase-separated borosilicate glass and thereby render the borosilicate glass porous.
A magnetic recording medium comprising a substrate having applied thereon at least a magnetic recording layer, said substrate comprising silica (SiO2) glass having a purity of 99% or more as a main component, the silica glass being a sea component of phase-separated borosilicate glass having an islands-in-sea structure, and having on the surface thereof a continuous texture derived from the porous structure of the silica glass, the texture having a surface roughness Ra of 1 to 10 nm and a pore size of 5 to 250 nm.
A method for producing a magnetic recording medium comprising a substrate having applied thereon at least a magnetic recording layer, in which said substrate comprises silica (SiO2) glass having a purity of 99% or more as a main component, the silica glass being a sea component of phase-separated borosilicate glass having an islands-in-sea structure, and having on the surface thereof a continuous texture derived from the porous structure of the silica glass, the texture having a surface roughness Ra of 1 to 10 nm and a pore size of 5 to 250 nm,
- the method comprising the steps of:
- heat treating a disk of borosilicate glass at a temperature of 500 to 750° C. to cause phase separation, thereby forming the phase-separated borosilicate glass;
- and
- treating the phase separated borosilicate glass with an acid selected from the group consisting of nitric acid, sulfuric acid, hydrochloric acid and acetic acid to dissolve out an islands component from the phase-separated borosilicate glass, thereby producing said substrate.
A magnetic disk device comprising a recording head part for recording information in a magnetic recording medium and a reproducing head part for reproducing the information, wherein the magnetic recording medium is a magnetic recording medium comprising a nonmagnetic substrate having provided thereon a magnetic recording layer and the substrate comprises silica (SiO2) glass having a purity of 99% or more as a main component, the silica glass being a sea component of phase-separated borosilicate glass having an islands-in-sea structure, and having on the surface thereof a continuous texture derived from the porous structure of the silica glass, the texture having a surface roughness Ra of 1 to 10 nm and a pore size of 5 to 250 nm.
Dependencies are inferred from the claim text.