US4639295A
Expired / Lapsed
US
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Zinc phosphating method
Assignee: Henkel Corp
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Filing: 1985-08-14
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Granted: 1987-01-27
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Expires: 2005-08-14
Abstract
Abstract A method for enhancing the corrosion resistance of a metal surface at the edge portion which comprises applying direct current to said metal surface as previously zinc phosphated as a negative electrode in an acidic solution comprising zinc ion in a concentration of 2 to 3 g/L, phosphate ion in a concentration of 8 to 14 g/L and chloride ion in a concentration of 3 to 6 g/L under the condition of 5 to 15 A/dm 2 (metal surface) at a temperature of 20° to 40° C. to make an electric zinc phosphate coating film having corrosion resistance.
Inventors
- 👤 Satoshi Miyamoto
- 👤 Masamichi Nagatani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:45
CPC Classifications
C; C23; C23C; C23C22/00; C23C22/82; C23C22/83; C25; C25D; C25D11/00; C25D11/36
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
88 words
In a method for applying a zinc phosphate coating to a metal substrate, wherein said substrate is first given a conventional zinc phosphate coating, the improvement comprising providing a further zinc phosphate coating by using said zinc phosphate-coated substrate as a negative electrode and applying a direct current thereto, in the presence of an electrolyte solution comprising zinc ions in a concentration of 2 to 3 g/l, phosphate ions in a concentration of 8 to 14 g/l and chloride ions in a concentration of 3 to 6 g/l.
Claim 2
Dependent Claim
88 words
In a method for applying a zinc phosphate coating to a metal substrate, wherein said substrate is first given a conventional zinc phosphate coating, the improvement comprising providing a further zinc phosphate coating by using said zinc phosphate-coated substrate as a negative electrode and applying a direct current thereto, in the presence of an electrolyte solution comprising zinc ions in a concentration of 2 to 3 g/l, phosphate ions in a concentration of 8 to 14 g/l and chloride ions in a concentration of 3 to 6 g/l.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein said phosphate ion concentration is 10 to 12 g/l and said chloride ion concentration is 4 to 5 g/l.
Claim 4
Dependent Claim
45 words
The method of claim 2 wherein said direct current is applied in an amount of 5 to 15 Amperes/square decimeter, said current application is effected for 30 seconds to 3 minutes, and said electrolyte solution is maintained at a temperature of 15° to 50° C.
Claim 5
Dependent Claim
45 words
The method of claim 2 wherein said direct current is applied in an amount of 9 to 11 Amperes/square decimeter, said current application is effected for 30 seconds to 3 minutes, and said electrolyte solution is maintained at a temperature of 20° to 40° C.
Claim 6
Dependent Claim
19 words
The method of claim 4 wherein said electrolyte solution is maintained at a temperature of 25° to 35° C.
Claim 7
Dependent Claim
20 words
The method of claim 1 wherein said direct current is applied in an amount of 5 to 15 Amperes/square decimeter.
Claim 8
Dependent Claim
20 words
The method of claim 1 wherein said direct current is applied in an amount of 9 to 11 Amperes/square decimeter.
Claim 9
Dependent Claim
19 words
The method of claim 1 wherein said direct current application is effected for from 30 seconds to 3 minutes.
Claim 10
Dependent Claim
19 words
The method of claim 1 wherein said electrolyte solution is maintained at a temperature of 15° to 50° C.
Claim 11
Dependent Claim
19 words
The method of claim 1 wherein said electrolyte solution is maintained at a temperature of 20° to 40° C.
Claim 12
Dependent Claim
19 words
The method of claim 1 wherein said electrolyte solution is maintained at a temperature of 25° to 35° C.
Claim 13
Dependent Claim
45 words
The method of claim 1 wherein said direct current is applied in an amount of 5 to 15 Amperes/square decimeter, said current application is effected for 30 seconds to 3 minutes, and said electrolyte solution is maintained at a temperature of 15° to 50° C.
Claim 14
Dependent Claim
45 words
The method of claim 1 wherein said direct current is applied in an amount of 9 to 11 Amperes/square decimeter, said current application is effected for 30 seconds to 3 minutes, and said electrolyte solution is maintained at a temperature of 20° to 40° C.
Claim 15
Dependent Claim
19 words
The method of claim 13 wherein said electrolyte solution is maintained at a temperature of 25° to 35° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-01-26 | 1990-07-28 | 1991-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-26 | 1994-07-28 | 1995-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-26 | 1998-07-28 | 1999-01-27 | $7700.00 | Window Closed / Lapsed |