US4702802A
Expired / Lapsed
US
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Method for making high corrosion resistance composite plated steel strip
Assignee: JFE Steel Corp
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Filing: 1986-07-09
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Granted: 1987-10-27
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Expires: 2006-07-09
Abstract
Abstract Composite plated steel strips comprising a zinc base layer electrodeposited on at least one surface of a steel strip exhibit excellent corrosion resistance with or without painting provided that the zinc base layer contains 0.1 to 10% by weight of cobalt, 0.05 to 5% by weight of chromium, 0.05 to 8% by weight of aluminum, and optionally, 0.05 to 5% by weight of Si, the balance being zinc. Such composite plated steel strips are prepared by subjecting a steel strip to composite electroplating in an acidic zinc plating bath which contains at least one water-soluble compound of Co 2+ in an amount of 0.3 to 60 g/l of metallic cobalt, at least one water-soluble compound of Cr 3+ in an amount of 0.2 to 2.5 g/l of metallic chromium, a pseudo-boehmite like alumina sol in an amount of 0.5 to 20 g/l of alumina, and optionally, colloidal silica in an amount of 0.5 to 20 g/l of silica at pH 1 or higher and a current density of at least 40 A/dm 2 .
Inventors
- 👤 Shigeru Umino
- 👤 Koji Yamato
- 👤 Hajime Kimura
- 👤 Toshio Ichida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:48
CPC Classifications
C; C23; C23C; C23C2/00; C23C2/04; C23C2/06; C25; C25D; C25D3/00; C25D3/02; C25D3/56; C25D3/565; Y; Y10; Y10S; Y10S428/00; Y10S428/922; Y10S428/9335; Y10S428/934; Y10S428/935; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12771; Y10T428/12785; Y10T428/12792; Y10T428/12799
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
88 words
In a method for preparing a high corrosion resistance composite plated steel strip, comprising subjecting a steel strip to composite electroplating in an acidic zinc plating bath; the improvement in which the bath also contains at least one water-soluble compound of Co 2+ in an amount of 0.3 to 60 g/l of metallic cobalt, at least one water-soluble compound of Cr 3+ in an amount of 0.3 to 2.5 g/l of metallic chromium, and a pseudo-boehmite alumina sol in an amount of 0.5 to 20 g/l of alumina.
Claim 2
Dependent Claim
88 words
In a method for preparing a high corrosion resistance composite plated steel strip, comprising subjecting a steel strip to composite electroplating in an acidic zinc plating bath; the improvement in which the bath also contains at least one water-soluble compound of Co 2+ in an amount of 0.3 to 60 g/l of metallic cobalt, at least one water-soluble compound of Cr 3+ in an amount of 0.3 to 2.5 g/l of metallic chromium, and a pseudo-boehmite alumina sol in an amount of 0.5 to 20 g/l of alumina.
Claim 3
Dependent Claim
31 words
A method according to claim 1 wherein the electroplating is conducted in the bath at pH of at least 1.0 and a current density of at least 40 A/dm 2 .
Claim 4
Dependent Claim
30 words
A method according to claim 1 wherein the electroplating is conducted in the bath at pH 2 to 3.5 and a current density of at least 60 A/dm 2 .
Claim 5
Dependent Claim
100 words
In a method for preparing a high corrosion resistance composite plated steel strip, comprising subjecting a steel strip to composite electroplating in an acidic zinc plating bath; the improvement in which the bath also contains at least one water-soluble compound of Co 2+ in an amount of 0.3 to 60 g/l of metallic cobalt, at least one water-soluble compound of Cr 3+ in an amount of 0.2 to 2.5 g/l of metallic chromium, a pseudo-boehmite alumina sol in an amount of 0.5 to 20 g/l of alumina, and colloidal silica in an amount of 0.5 to 20 g/l of silica.
Claim 6
Dependent Claim
100 words
In a method for preparing a high corrosion resistance composite plated steel strip, comprising subjecting a steel strip to composite electroplating in an acidic zinc plating bath; the improvement in which the bath also contains at least one water-soluble compound of Co 2+ in an amount of 0.3 to 60 g/l of metallic cobalt, at least one water-soluble compound of Cr 3+ in an amount of 0.2 to 2.5 g/l of metallic chromium, a pseudo-boehmite alumina sol in an amount of 0.5 to 20 g/l of alumina, and colloidal silica in an amount of 0.5 to 20 g/l of silica.
Claim 7
Dependent Claim
31 words
A method according to claim 4 wherein the electroplating is conducted in the bath at pH of at least 1.0 and a current density of at least 40 A/dm 2 .
Claim 8
Dependent Claim
30 words
A method according to claim 4 wherein the electroplating is conducted in the bath at pH 2 to 3.5 and a current density of at least 60 A/dm 2 .
References Cited (Backward Citations)
US4064320A
Cited
US4325790A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-26 | 1991-04-27 | 1991-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-26 | 1995-04-27 | 1995-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-26 | 1999-04-27 | 1999-10-27 | $7700.00 | Window Closed / Lapsed |