# US 10,767,247 B2 · Aluminum alloy magnetic disk substrate and method for producing same

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- Number: US 10,767,247 B2
- Document ID: US10767247B2
- Status: Granted
- Kind: B2
- Application number: 16/482,113
- Filed: 2018-01-30
- Published: 2019-12-26
- Granted: 2020-09-08
- Earliest claimed: 2017-02-01
- Assignees: Uacj Corporation; Furukawa Electric Co., Ltd.
- Applicants: Uacj Corporation; Furukawa Electric Co., Ltd.
- Inventors: Takuya Murata; Kotaro Kitawaki; Makoto Yonemitsu; Naoki Kitamura; Takashi Nakayama; Hideyuki Hatakeyama; Ryo Sakamoto; Sadayuki Toda
- Web page: https://patentgrep.com/patent/US10767247B2

## CPC

- C23G 1/125: {aluminium}
- C22C 21/00: Alloys based on aluminium
- C22F 1/04: of aluminium or alloys based thereon
- C23C 18/1637: {metallic substrate}
- C23C 18/1651: {Two or more layers only obtained by electroless plating}
- C23C 18/1689: {After-treatment}
- C23C 18/18: Pretreatment of the material to be coated
- C23C 18/1827: {only one step pretreatment}
- C23C 18/1844: {with use of organic or inorganic compounds other than metals, first}
- C23C 18/32: Coating with nickel, cobalt or mixtures thereof with phosphorus or boron (C23C18/50 takes precedence)
- C23C 18/54: Contact plating, i.e. electroless electrochemical plating
- C23F 1/20: for etching aluminium or alloys thereof
- G11B 5/73913: {Composites or coated substrates}
- G11B 5/73919: {Aluminium or titanium elemental or alloy substrates}
- G11B 5/8404: {manufacturing base layers}
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

There are provided: an aluminum alloy magnetic disk substrate including: an aluminum alloy base material including an aluminum alloy containing 0.4 to 3.0 mass % (hereinafter, simply referred to as “%”) of Fe, 0.1 to 3.0% of Mn, 0.005 to 1.000% of Cu, and 0.005 to 1.000% of Zn, with the balance of Al and unavoidable impurities; and an electroless Ni—P plated layer formed on a surface of the aluminum alloy base material, in which the peak value (BLEI) of Fe emission intensity at an interface between the electroless Ni—P plated layer and the aluminum alloy base material, as determined by a glow discharge optical emission spectrometry device, is lower than Fe emission intensity (AlEI) in the interior of the aluminum alloy base material, as determined by the glow discharge optical emission spectrometry device; and a method for producing the aluminum alloy magnetic disk substrate.

## Claims

### Claim 1

An aluminum alloy magnetic disk substrate comprising: an aluminum alloy base material comprising an aluminum alloy containing 0.4 to 3.0 mass % of Fe, 0.1 to 3.0 mass % of Mn, 0.005 to 1.000 mass % of Cu, and 0.005 to 1.000 mass % of Zn, with a balance of Al and unavoidable impurities; and an electroless Ni—P plated layer formed on a surface of the aluminum alloy base material, wherein a maximum value (BLEI) of Fe emission intensity in a range of 50 to 84% of Al emission intensity in an interior of the aluminum alloy base material, at an interface between the electroless Ni—P plated layer and the aluminum alloy base material, as determined by a glow discharge optical emission spectrometry device, is lower than Fe emission intensity (AIEI) in the aluminum alloy base material, as determined by the glow discharge optical emission spectrometry device.

### Claim 2 (depends on 1)

The aluminum alloy magnetic disk substrate according to claim 1, wherein BLEI/AIEI is 0.9 or less in a relationship between BLEI and AIEI.

### Claim 3 (depends on 1)

The aluminum alloy magnetic disk substrate according to claim 1, wherein a density of a compound present in a region from a surface, closer to the interface, of the aluminum alloy base material to a depth of 1 μm in a thickness direction is 20000 particles/mm2 or less.

### Claim 4 (depends on 1)

The aluminum alloy magnetic disk substrate according to claim 1, wherein the aluminum alloy further comprises one or more selected from 0.1 to 0.4 mass % of Si, 0.1 to 3.0 mass % of Ni, 0.1 to 6.0 mass % of Mg, 0.01 to 1.00 mass % of Cr, and 0.01 to 1.00 mass % of Zr.

### Claim 5 (depends on 1)

The aluminum alloy magnetic disk substrate according to claim 1, wherein the aluminum alloy further comprises one or more selected from Ti, B, and V, of which a total content is 0.005 to 0.500 mass %.

### Claim 6 (depends on 1)

A method for producing the aluminum alloy magnetic disk substrate according to claim 1, the method comprising: a step of preparing an aluminum alloy sheet, comprising subjecting the aluminum alloy to a casting stage, a hot-rolling stage, and a cold-rolling stage in an order mentioned above; a step of preparing the aluminum alloy base material, comprising subjecting an annular aluminum alloy sheet obtained by stamping the aluminum alloy sheet to have an annular shape to a pressurization flattening annealing stage, a cutting/grinding work stage, and a strain-removing heat treatment stage in an order mentioned above; a plating pretreatment step comprising subjecting the aluminum alloy base material to an alkaline degreasing treatment stage, an acid-etching treatment stage, a desmutting treatment stage, and a zincate treatment stage in an order mentioned above; and an electroless Ni—P plating treatment step of performing electroless Ni—P plating treatment of a surface of the aluminum alloy base material subjected to the plating pretreatment step, wherein the method for producing the aluminum alloy magnetic disk substrate further comprises a compound removal step of performing immersion for 5 to 60 seconds in a mixed solution of HNO3/HF that is 10 to 60 mass % HNO3 solution at 10 to 30° C. and contains 10 to 80 g/L of HF, after the cutting/grinding work stage and before the zincate treatment stage.

### Claim 7 (depends on 6)

The method for producing the aluminum alloy magnetic disk substrate according to claim 6, the method further comprising either or both of a homogenization treatment stage between the casting stage and the hot-rolling stage and an annealing treatment stage before or in the cold-rolling stage.