Manufacturing method of surface-treated zinc-nickel alloy electroplated steel sheet having excellent corrosion resistivity and paintability

Patent metadata

Field	Value
Publication number	US-2021285118-A1
Application number	US-201917257927-A
Country	US
Kind code	A1
Filing date	Jun 28, 2019
Priority date	Jul 6, 2018
Publication date	Sep 16, 2021
Grant date	—

Abstract

Provided is a manufacturing method of a surface-treated Zn—Ni alloy electroplated steel sheet, the method comprising the steps of: preparing a Zn—Ni alloy electroplated steel sheet including a steel sheet and a Zn—Ni alloy-plated layer with an Ni content of 5-20 wt % (S1); preparing an alkaline electrolyte solution in which 4-250 g/L of potassium hydroxide (KOH) or sodium hydroxide (NaOH) or both combined are added in distilled water (S2); and inside the alkaline electrolyte solution, placing the Zn—Ni alloy electroplated steel sheet as an anode and installing another metal sheet as a cathode, and applying 2-10 V of an alternating or direct current to conductor electrochemical etching such that a 3-point average value of the arithmetic average roughness (Ra) of the surface of the Zn—Ni alloy electroplated steel sheet reaches 200-400 nm, thereby producing a surface-treated electroplated steel sheet (S3).

First claim

1 . A manufacturing method of a surface-treated Zn—Ni alloy electroplated steel sheet, comprising:
preparing a Zn—Ni alloy electroplated steel sheet comprising a steel sheet and a Zn—Ni alloy-plated layer in which a content of Ni formed on the steel sheet is 5 wt % to 20 wt % (S1);
preparing an alkaline electrolytic solution in which 4 g/L to 250 g/L of potassium hydroxide (KOH), sodium hydroxide (NaOH), or both thereof is added to distilled water (S2);
inside the alkaline electrolytic solution, obtaining a surface-treated electroplated steel sheet by placing the Zn—Ni alloy electroplated steel sheet as an anode and installing another metal sheet as a cathode, and applying 2 V to 10 V of an alternating or direct current to conduct electrolytic etching such that a 3-point average value of an arithmetic average roughness (Ra) of a surface of the Zn—Ni alloy electroplated steel sheet reaches 200 nm to 400 nm (S3).

2 . The manufacturing method according to claim 1 , wherein, in S2 of preparing the alkaline electrolytic solution, 60 g/L to 250 g/L of KOH or NaOH is added.

3 . The manufacturing method according to claim 1 , wherein the 3-point average value of the arithmetic average roughness (Ra) is 200 nm to 250 nm.

4 . The manufacturing method according to claim 1 , wherein a 3-point average value of a root-mean-square roughness (Rq) of the surface of the surface-treated Zn—Ni alloy-electroplated steel sheet after S3 of obtaining the surface-treated electroplated steel sheet is 290 nm to 600 nm.

5 . The manufacturing method according to claim 1 , wherein a 3-point average value of a maximum roughness (Rmax) of the surface of the surface-treated Zn—Ni alloy-electroplated steel sheet after S3 of obtaining the surface-treated electroplated steel sheet is 2900 nm to 5000 nm.

Assignees

• Posco

Inventors

• Lee Kang-Min
• Yoo Hye-Jin
• Baek Je-Hoon
• Byeon Chang-Se
• Kim Jung-Su

Classifications

• C25D5/48 Primary

  After-treatment of electroplated surfaces · CPC title

• C25F3/02

  Etching · CPC title

• C25D3/565 Primary

  containing more than 50% by weight of zinc · CPC title

• C25D5/36

  of iron or steel · CPC title

• C25F3/06

  of iron or steel · CPC title