Magnetic disk substrate and magnetic disk using magnetic disk substrate
AssigneesUacj Corporation, Furukawa Electric Co., Ltd.
InventorsKotaro Kitawaki, Hideyuki Hatakeyama, Wataru Kumagai, Ryo Sakamoto
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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.
Claims22
A magnetic disk substrate, wherein, when f (Hz) is a resonance frequency, ρ (g/cm3) 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.
A magnetic disk substrate comprising a glass material including SiO2:
- 55 to 75 mass % as a main component and to which Al2O3:
- 0.3 to 25 mass % and CaO:
- 0 to 20 mass % are added, 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, wherein the glass material further includes one more of ZrO2:
- up to 10 mass % and TiO2:
- 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.
Dependencies are inferred from the claim text.