Steel sheet for cans and production method for steel sheet for cans

Patent metadata

Field	Value
Publication number	US-10753005-B2
Application number	US-201616061079-A
Country	US
Kind code	B2
Filing date	Dec 1, 2016
Priority date	Dec 11, 2015
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

A steel sheet for cans has, on the surface thereof, in order from the steel sheet side, a chromium metal layer and a hydrous chromium oxide layer. The chromium metal layer is deposited in an amount of 65-200 mg/m2, and the hydrous chromium oxide layer is deposited in an amount of 3-15 mg/m2 in terms of chromium. The chromium metal layer includes: a flat chromium metal layer that has a thickness of at least 7 nm; and a granular chromium metal layer that includes granular protrusions that are formed on the surface of the flat chromium metal layer. The maximum grain size of the granular protrusions is 100 nm or smaller. The number density of the granular protrusions per unit area is 10/μm2 or higher.

First claim

The invention claimed is:

1. A steel sheet for cans comprising, on a surface of a steel sheet, a chromium metal layer and a hydrated chromium oxide layer stacked in this order from a steel sheet side,
wherein the chromium metal layer has a coating weight of 65 to 200 mg/m 2 ,
the hydrated chromium oxide layer has a coating weight of 3 to 15 mg/m 2 in terms of chromium amount, and
the chromium metal layer includes:
a flat chromium metal layer with a thickness of not less than 7 nm; and
a granular chromium metal layer having granular protrusions formed on a surface of the flat chromium metal layer, the granular protrusions having a maximum diameter of not more than 100 nm and a number density per unit area of not less than 10 protrusions/μm 2 .

2. The steel sheet according to claim 1 , wherein the granular protrusions have a maximum diameter of not more than 50 nm.

3. The steel sheet according to claim 2 , wherein the granular protrusions have a maximum diameter of not more than 30 nm.

4. The steel sheet according to claim 3 , wherein the granular protrusions have a number density per unit area of not less than 50 protrusions/μm 2 .

5. The steel sheet according to claim 4 , wherein the granular protrusions have a number density per unit area of not less than 100 protrusions/μm 2 .

6. The steel sheet according to claim 5 , wherein the flat chromium metal layer has a thickness of not less than 10 nm.

7. The steel sheet according to claim 1 , wherein the granular protrusions have a number density per unit area of not less than 50 protrusions/μm 2 .

8. The steel sheet according to claim 7 , wherein the granular protrusions have a number density per unit area of not less than 100 protrusions/μm 2 .

9. The steel sheet according to claim 1 , wherein the flat chromium metal layer has a thickness of not less than 10 nm.

10. A method of manufacturing the steel sheet according to claim 1 , comprising:
subjecting a steel sheet to prior-stage cathodic electrolysis treatment with an aqueous solution that contains Cr in an amount of not less than 0.5 mol/L and F in an amount of more than 0.10 mol/L and is free of sulfuric acid except for sulfuric acid inevitably incorporated therein, followed by anodic electrolysis treatment at an electric quantity density of not less than 0.1 C/dm 2 but less than 5.0 C/dm 2 , and then by posterior-stage cathodic electrolysis treatment.

11. The method according to claim 10 , wherein the posterior-stage cathodic electrolysis treatment is a final electrolysis treatment.

12. The method according to claim 10 , wherein the aqueous solution used in the prior-stage cathodic electrolysis treatment, the anodic electrolysis treatment and the posterior-stage cathodic electrolysis treatment comprises only one type of aqueous solution.

13. The method according to claim 11 , wherein the aqueous solution used in the prior-stage cathodic electrolysis treatment, the anodic electrolysis treatment and the posterior-stage cathodic electrolysis treatment comprises only one type of aqueous solution.

14. A method of manufacturing the steel sheet according to claim 6 , comprising:
subjecting a steel sheet to prior-stage cathodic electrolysis treatment with an aqueous solution that contains Cr in an amount of not less than 0.5 mol/L and F in an amount of more than 0.10 mol/L and is free of sulfuric acid except for sulfuric acid inevitably incorporated therein, followed by anodic electrolysis treatment at an electric quantity density of not less than 0.1 C/dm 2 but less than 5.0 C/dm 2 , and then by posterior-stage cathodic electrolysis treatment.

15. The method according to claim 14 , wherein the posterior-stage cathodic electrolysis treatment is a final electrolysis treatment.

16. The method according to claim 14 , wherein the aqueous solution used in the prior-stage cathodic electrolysis treatment, the anodic electrolysis treatment and the posterior-stage cathodic electrolysis treatment comprises only one type of aqueous solution.

17. The method according to claim 15 , wherein the aqueous solution used in the prior-stage cathodic electrolysis treatment, the anodic electrolysis treatment and the posterior-stage cathodic electrolysis treatment comprises only one type of aqueous solution.

Assignees

• Jfe Steel Corp

Inventors

• Nakagawa Yusuke
• Suzuki Takeshi
• Suto Mikito
• Kojima Katsumi
• Baba Yuya

Classifications

• C25F3/08

  of refractory metals · CPC title

• C25D9/06

  by anodic processes · CPC title

• C25D3/08

  Deposition of black chromium {, e.g. hexavalent chromium, CrVI} · CPC title

• C23C28/3455

  with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer · CPC title

• C23C28/322 Primary

  only coatings of metal elements only · CPC title