Surface-treated steel sheet and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-12270109-B2
Application number	US-201816759204-A
Country	US
Kind code	B2
Filing date	Oct 26, 2018
Priority date	Oct 27, 2017
Publication date	Apr 8, 2025
Grant date	Apr 8, 2025

Abstract

A surface-treated steel sheet, including: a steel sheet; and a nickel-cobalt-iron diffusion layer formed as an outermost surface layer on the steel sheet. When a content of Ni, a content of Co and a content of Fe of the nickel-cobalt-iron diffusion layer are determined based on a Ni intensity, a Co intensity and a Fe intensity each sequentially measured in the depth direction from the surface side of the nickel-cobalt-iron diffusion layer by a radio frequency glow discharge optical emission spectrometry, a content of Co at a specific depth position D, In Co_D , is 5% by mass or higher and a content of Fe at the specific depth position D, In Fe_D , is 11% by mass or higher, the specific depth position D being a position where the Ni intensity is 0.5% of the maximum value of the Ni intensity. Also disclosed is a method for manufacturing the surface-treated steel sheet.

First claim

The invention claimed is:

1. A surface-treated steel sheet, comprising:
a steel sheet; and
a nickel-cobalt-iron diffusion layer formed as an outermost surface layer on the steel sheet,
wherein when a content of Ni, a content of Co and a content of Fe of the nickel-cobalt-iron diffusion layer are determined based on a Ni intensity, a Co intensity and a Fe intensity each sequentially measured in the depth direction from the surface side of the nickel-cobalt-iron diffusion layer by a radio frequency glow discharge optical emission spectrometry, a content of Co at a specific depth position D, In Co_D , is 8.59% by mass or higher and 65% by mass or lower, a content of Fe at the specific depth position D, In Fe_D , is 18% by mass or higher and 70% by mass or lower, a content of Ni at the specific depth position D, In Ni_D is 5% by mass or higher and 34.55% by mass or lower, the specific depth position D being a position where the Ni intensity is 0.5% of the maximum value of the Ni intensity, and
wherein the total content of nickel and cobalt in the nickel-cobalt-iron diffusion layer is 9.0 g/m 2 or lower.

2. The surface-treated steel sheet according to claim 1 , wherein the nickel-cobalt-iron diffusion layer has a content of cobalt of 0.2 g/m 2 or higher.

3. The surface-treated steel sheet according to claim 1 , wherein the nickel-cobalt-iron diffusion layer has R Fe/Co (In Fe_D /In Co_D ) of 0.5 to 20, the R Fe/Co (In Fe_D /In Co_D ) being a ratio of the content of Fe, In Fe_D , with respect to the content of Co, In Co_D .

4. The surface-treated steel sheet according to claim 1 , further comprising an iron-nickel diffusion layer between the steel sheet and the nickel-cobalt-iron diffusion layer.

5. A battery case comprising the surface-treated steel sheet according to claim 1 .

6. A battery comprising the battery case according to claim 5 .

7. A method for manufacturing the surface-treated steel sheet according to claim 1 , comprising: a step of forming a nickel-cobalt alloy plating layer having a total content of nickel and cobalt of 9.0 g/m 2 or lower on a steel sheet, and a step of subjecting the steel sheet having the nickel-cobalt alloy plating layer formed thereon to a heat treatment at a temperature of 480 of 900° C. to thereby form the nickel-cobalt-iron diffusion layer as an outermost surface layer.

Assignees

• Toyo Kohan Co Ltd

Inventors

• Nakano Yuji
• Matsushige Daisuke
• Yoshioka Koh

Classifications

• C23C28/021

  including at least one metal alloy layer · CPC title

• B32B15/011

  all layers being formed of iron alloys or steels · CPC title

• H01M50/182

  for cells with a collector centrally disposed in the active mass, e.g. Leclanché cells · CPC title

• H01M50/1243

  characterised by the internal coating on the casing · CPC title

• H01M50/128

  with two or more layers of only inorganic material · CPC title