The present invention provides: an aluminum alloy substrate for magnetic discs with excellent plating surface smoothness; a manufacturing method therefor; and a magnetic disc using said aluminum alloy substrate for magnetic discs. The present invention is an aluminum alloy substrate for magnetic discs, a manufacturing method therefor, and a magnetic disc using said aluminum alloy substrate for magnetic discs, the aluminum alloy substrate being characterized in being obtained from an aluminum alloy containing Mg: 2.0-8.0 mass % (% below), Be: 0.00001-0.00200%, Cu: 0.003-0.150%, Zn: 0.05-0.60%, Cr: 0.010-0.300%, Si: 0.060% or less, Fe: 0.060% or less, the balance being obtained from Al and unavoidable impurities.

A magnetic-disk glass substrate containing an alkaline earth metal component as a glass composition includes an edge surface that is a mirror surface, and has a roughness percentage of 40% or more when a bearing ratio of a roughness cross-sectional area is 50% in a bearing ratio curve of roughness cross-sectional areas obtained when a surface roughness of the edge surface obtained after the edge surface is etched by 2.5 m is measured.

Perpendicular magnetic recording media including a carbon grain isolation initiation layer for reducing intergranular exchange coupling in the recording layer are provided. In one such case, the media includes a substrate, a plurality of underlayers on the substrate, a grain isolation initiation layer (GIIL) on the plurality of underlayers, the GIIL including C, a metal, and an oxide, and a magnetic recording layer directly on the GIIL and including a non-ordered structure. In another case, a method of fabricating such magnetic media is provided.

Letting a particle diameter be Dx (m) when a cumulative particle volume cumulated from the small particle diameter side reaches x(%) of the total particle volume in a particle size distribution obtained regarding cerium oxide included in a polishing liquid using a laser diffraction/scattering method, D5 is 1 m or less, and a difference between D95 and D5 is 3 m or more.

A base for a magnetic recording medium, includes a substrate made of an Al alloy and having a surface, and a film made of a NiWP-based alloy and plated on the surface of the substrate. The film includes W in a range of 15 mass % to 22 mass %, P in a range of 3 mass % to 10 mass %, and Pb in a range of 0.03 mass % to 0.08 mass %. The film has a thickness of 5 m or greater.

Embodiments provide a polishing composition for a magnetic disk substrate, which contains colloidal silica having an average primary particle size of 5 to 200 nm, fumed silica having an average particle size of 30 to 800 nm, pulverized wet-process silica particles having an average particle size of 100 to 1000 nm, and water. According to an embodiment, a ratio of the colloidal silica is 5 to 90% by mass, a ratio of the fumed silica is 5 to 90% by mass, and a ratio of the pulverized wet-process silica particles is 5 to 90% by mass with respect to all the silica particles, and a concentration of all the silica particles is 1 to 50% by mass.

Provided is a manufacturing method of a magnetic recording medium, in which the magnetic recording medium includes a magnetic layer including ferromagnetic powder and a binding agent on a non-magnetic support, and the magnetic layer shows a natural ferromagnetic resonance frequency equal to or greater than 30.0 GHz, the method including: forming a servo pattern on the magnetic layer by microwave-assisted recording.

The invention relates to a tape drive, and to a method and a computer program product for operating a tape drive. The tape drive may include a transport mechanism which may include a tape head. The tape drive may be adapted to receive a magnetic tape with the transport mechanism, and to transport the magnetic tape by the transport mechanism. The tape head may be adapted to perform read-write operations on an oxide side of the magnetic tape. The tape drive may include a burnishing unit, which may include a burnishing roller and a burnish controller having an abrasive shell. The burnishing roller may be installed in the tape drive upstream of the tape head such that the abrasive shell supports the received magnetic tape on the oxide side. The burnish controller may be adapted to control the movement of the burnishing roller.

A method for plating nickel onto a glass surface of a substrate by sequentially contacting the surface with a solution having an oxidizing agent, a solution containing a silane compound, a Pd/Sn solution, and a nickel ion-containing solution, thereby accomplishing an electroless nickel plating process.

Described are chemical mechanical processing (CMP) compositions and related methods, including compositions and methods for polishing nickel-containing substrate surfaces such as nickel phosphorus (NiP) surfaces for hard disk applications, wherein the compositions contain highly irregular-shaped fused silica abrasive particles.