US3930897A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of treating an object of silicon steel provided with an insulating protective coating of silicate with a solution of phosphate
Assignee: ABB Norden Holding AB
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Filing: 1974-10-25
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Granted: 1976-01-06
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Expires: 1994-10-25
Abstract
Abstract An object of silicon steel, such as sheet and strip for motors, generators and transformers, which has an insulating coating of silicate, is provided with a solution of phosphate by applying to the silicate-coated object an aqueous solution containing phosphate ions and complex metal-ammonia ions and heating the coated object to a temperature of at least about 550°C for a time sufficient to anchor the resulting phosphate layer to the silicate coating. The solution has a pH-value of at least 9, and consists essentially of monophosphate ions. The metal ions are cupric ions and/or chromic ions. An insoluble filler may be added to the aqueous solution.
Inventors
- 👤 Carl-Artur Akerblom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:07
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/14; H01F1/147; H01F1/14766; H01F1/14775; H01F1/14783; C; C23; C23C; C23C24/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
108 words
Method of producing a phosphate coating on an object of silicon steel having an insulating coating of silicate, with a solution of phosphate, which comprises coating the object with an aqueous solution containing phosphate ions and complex metal-ammonia ions consisting essentially of cupric and/or chromic ions, said aqueous solution having a content of phosphate ions, complex metal ions, ammonium ions and dissolved ammonia of together 5 to 50 per cent by weight, the solution having a pH of at least 9, and heating the coated object to a temperature of at least about 550°C for a time sufficient to anchor the resulting phosphate layer to the silicate coating.
Claim 2
Dependent Claim
108 words
Method of producing a phosphate coating on an object of silicon steel having an insulating coating of silicate, with a solution of phosphate, which comprises coating the object with an aqueous solution containing phosphate ions and complex metal-ammonia ions consisting essentially of cupric and/or chromic ions, said aqueous solution having a content of phosphate ions, complex metal ions, ammonium ions and dissolved ammonia of together 5 to 50 per cent by weight, the solution having a pH of at least 9, and heating the coated object to a temperature of at least about 550°C for a time sufficient to anchor the resulting phosphate layer to the silicate coating.
Claim 3
Dependent Claim
15 words
Method according to claim 1, in which the phosphate ions consist essentially of monophosphate ions.
Claim 4
Dependent Claim
21 words
Method according to claim 1, which comprises heating the object with the applied phosphate solution to a temperature of 700°to 850°C.
Claim 5
Dependent Claim
13 words
Method according to claim 1, in which the solution contains an insoluble filler.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-05 | 1979-07-07 | 1980-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-05 | 1983-07-07 | 1984-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-05 | 1987-07-07 | 1988-01-06 | $7700.00 | Window Closed / Lapsed |