Aluminum alloy plate for magnetic disc substrate, method for manufacturing same, and method for manufacturing magnetic disc

Patent metadata

Field	Value
Publication number	US-2016351224-A1
Application number	US-201515117209-A
Country	US
Kind code	A1
Filing date	Sep 24, 2015
Priority date	Sep 27, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

An aluminum alloy plate for a magnetic disk substrate with a flat and smooth ground surface, a production method by which the aluminum alloy plate can be produced at low cost and a magnetic disk are shown. An aluminum alloy plate for a magnetic disk substrate which comprises an aluminum alloy containing Mg: 3.0 to 8.0 mass % (hereinafter %), Cu: 0.005 to 0.150%, Zn: 0.05 to 0.60%, Cr: 0.010 to 0.300%, Fe: 0.001 to 0.030%, Si: 0.001 to 0.030%, (Ti+V+Zr): 0.0010 to 0.0100%, B: 0.0001 to 0.0010% with a balance being Al and inevitable impurities, wherein the density of a Ti—V—B—Zr-based inclusion having a maximum diameter exceeding 5 μm is 0 piece/6000 mm 2 and the density of a Ti—V—B—Zr-based inclusion having a maximum diameter of 3 to 5 μm is 1 piece/6000 mm 2 or less; a production method thereof; and a method for producing a magnetic disk.

First claim

1 . An aluminum alloy plate for a magnetic disk substrate
wherein the aluminum alloy plate comprises an aluminum alloy containing Mg: 3.0 to 8.0 mass %, Cu: 0.005 to 0.150 mass %, Zn: 0.05 to 0.60 mass %, Cr: 0.010 to 0.300 mass %, Fe: 0.001 to 0.030 mass %, Si: 0.001 to 0.030 mass %, further containing (Ti+V+Zr): 0.0010 to 0.0100 mass %, B: 0.0001 to 0.0010 mass % with a balance being Al and inevitable impurities and wherein the density of a Ti—V—B—Zr-based inclusion having a maximum diameter exceeding 5 μm is 0 piece/6000 mm 2 and the density of a Ti—V—B—Zr-based inclusion having a maximum diameter of 3 to 5 μm is 1 piece/6000 mm 2 or less.

2 . A method for producing aluminum alloy plate for a magnetic disk substrate, which produces the aluminum alloy plate for a magnetic disk substrate according to claim 1 , comprising
a molten alloy holding step of holding a molten aluminum alloy in a holding furnace at 700 to 850° C. for 30 minutes or longer, a casting step of casting a slab from the molten alloy held in the molten alloy holding step, wherein the temperature of the molten alloy at the start of casting is 700 to 850° C., a hot rolling step of hot rolling the cast slab, and a cold rolling step of cold rolling the hot-rolled plate.

3 . A method for producing a magnetic disk, comprising
a step of punching a circular shape out of the aluminum alloy plate for a magnetic disk substrate according to claim 1 and thus preparing a disk blank, a step of flattening the disk blank by pressure annealing, a processing step of lathing, grinding, degreasing and etching the flattened disk blank, a step of zincating the processed aluminum alloy plate, a step of base-plating the zincated aluminum alloy plate, and a step of sputtering a magnetic material to a surface of the base-plated aluminum alloy plate.

Assignees

• Uacj Corp

Inventors

• Kitawaki Kotaro
• Hayashi Minoru
• Hashimoto Yoshiji
• Hisamoto Toshikazu

Classifications

• B21B2001/225

  by hot-rolling · CPC title

• B22D15/00

  Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor · CPC title

• C22C21/08

  with silicon · CPC title

• C23C18/36

  using hypophosphites · CPC title

• G11B5/8404 Primary

  manufacturing base layers · CPC title