Magnetic disk substrate and magnetic disk using magnetic disk substrate

Patent metadata

Field	Value
Publication number	US-12555602-B2
Application number	US-202118002695-A
Country	US
Kind code	B2
Filing date	Jun 30, 2021
Priority date	Jul 3, 2020
Publication date	Feb 17, 2026
Grant date	Feb 17, 2026

Abstract

A magnetic disk substrate includes an aluminum alloy including one type or two or more types of Fe: 8.5 mass % or less, Mn: 2.5 mass % or less, Ni: 6.5 mass % or less, and Mg: 4.5 mass % or less, a balance being Al and unavoidable impurities, wherein, when f (Hz) is a resonance frequency, ρ (g/cm3) is a density, and t (mm) is a plate thickness, (f×ρ/t) is 3800 or greater; and a magnetic disk using the magnetic disk substrate.

First claim

The invention claimed is:

1 . A magnetic disk substrate, wherein, when f (Hz) is a resonance frequency, ρ (g/cm 3 ) is a density, and t (mm) is a plate thickness of the magnetic disk substrate, (f×ρ/t) is 3800 or greater, wherein the magnetic disk substrate comprises an aluminum alloy including one or more of Zr: up to 0.20 mass %, Be: up to 0.0015 mass %, Sr: up to 0.1 mass %, Na: up to 0.1 mass %, and P: up to 0.1 mass %, a balance being Al and unavoidable impurities, wherein the resonance frequency is between 500 and 1500 Hz when measured at an impact acceleration of 30 to 50 G.

2 . The magnetic disk substrate according to claim 1 , wherein the aluminum alloy includes one or more of Fe: 8.5 mass % or less, Mn: 2.5 mass % or less, Ni: 6.5 mass % or less, and Mg: 4.5 mass % or less, wherein the aluminum alloy further includes one or more of Zn: 0.7 mass % or less, Cu: 1.0 mass % or less, and Cr: 0.30 mass % or less.

3 . A magnetic disk substrate comprising a glass material including SiO 2 : 55 to 75 mass % as a main component and to which Al 2 O 3 : 0.3 to 25 mass % and CaO: 0 to 20 mass % are added, wherein when f (Hz) is a resonance frequency, ρ (g/cm 3 ) is a density, and t (mm) is a plate thickness, (f×ρ/t) is 3800 or greater, wherein the glass material further includes one more of ZrO 2 : up to 10 mass % and TiO 2 : up to 1 mass %, wherein the resonance frequency is between 500 and 1500 Hz when measured at an impact acceleration of 30 to 50 G.

4 . The magnetic disk substrate according to claim 3 , wherein the glass material further includes one or more of Li 2 O: 0.01 to 6 mass %, Na 2 O: 0.7 to 12 mass %, and K 2 O: 0 to 8 mass %, MgO: 0 to 7 mass %.

5 . The magnetic disk substrate according to claim 3 , wherein the glass material further includes one or more of B 2 O 3 , SrO, BaO, ZnO, SnO 2 , Fe 2 O 3 , As 2 O 3 , and Sb 2 O 3 , respectively at 15 mass % or less.

6 . The magnetic disk substrate according to claim 1 , wherein the (f×ρ/t) is 4000 or greater.

7 . The magnetic disk substrate according to claim 1 , wherein the (f×ρ/t) is 4200 or greater.

8 . The magnetic disk substrate according to claim 1 , wherein a weight per one magnetic disk is from 6.0 to 11.0 g.

9 . The magnetic disk substrate according to claim 1 , wherein a weight per one magnetic disk is from 6.0 to 10.5 g.

10 . The magnetic disk substrate according to claim 1 , wherein a weight per one magnetic disk is from 6.0 to 8.7 g.

11 . The magnetic disk substrate according to claim 7 , wherein a weight per one magnetic disk is from 6.0 to 11.0 g.

12 . The magnetic disk substrate according to claim 7 , wherein a weight per one magnetic disk is from 6.0 to 8.7 g.

13 . A magnetic disk comprising a magnetic body layer on a surface of the magnetic disk substrate according to claim 8 .

14 . The magnetic disk substrate according to claim 8 , wherein the magnetic disk substrate has an outer diameter of 97 mm.

15 . A magnetic disk comprising a magnetic body layer on a surface of the magnetic disk substrate according to claim 10 .

16 . The magnetic disk substrate according to claim 10 , wherein the magnetic disk substrate has an outer diameter of 97 mm.

17 . A magnetic disk comprising a magnetic body layer on a surface of the magnetic disk substrate according to claim 11 .

18 . The magnetic disk substrate according to claim 11 , wherein the magnetic disk substrate has an outer diameter of 97 mm.

19 . A magnetic disk comprising a magnetic body layer on a surface of the magnetic disk substrate according to claim 12 .

20 . The magnetic disk substrate according to claim 12 , wherein the magnetic disk substrate has an outer diameter of 97 mm.

21 . The magnetic disk substrate according to claim 13 , wherein the magnetic disk substrate has an outer diameter of 97 mm.

22 . The magnetic disk substrate according to claim 15 , wherein the magnetic disk substrate has an outer diameter of 97 mm.

Assignees

• Uacj Corp
• Furukawa Electric Co Ltd

Inventors

• Kitawaki Kotaro
• Hatakeyama Hideyuki
• Kumagai Wataru
• Sakamoto Ryo

Classifications

• G11B5/82

  Disk carriers · CPC title

• B32B2307/208

  Magnetic, paramagnetic · CPC title

• B32B17/061 Primary

  of metal · CPC title

• B32B15/20

  comprising aluminium or copper {(B32B15/016 and B32B15/017 take precedence)} · CPC title

• B32B2307/7375

  Linear, e.g. length, distance or width · CPC title