US4242155A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming an insulating film on a grain-oriented silicon steel sheet
Assignee: JFE Steel Corp
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Filing: 1979-04-23
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Granted: 1980-12-30
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Expires: 1999-04-23
Abstract
Abstract A highly adhesive and uniform insulating film can be formed on a grain-oriented silicon steel sheet without deteriorating the iron loss of the steel sheet by the use of a magnesia series annealing separator containing a strontium compound.
Inventors
- 👤 Nobuyuki Morito
- 👤 Toshitomo Sugiyama
- 👤 Yasuo Yokoyama
- 👤 Toshio Ichida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 15:29
CPC Classifications
C; C21; C21D; C21D8/00; C21D8/12; C21D8/1277; C21D8/1283; C23; C23D; C23D5/00; C23D5/10
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
130 words
A method of forming a highly adhesive and uniform insulating film on a grain-oriented silicon steel sheet, without deteriorating the iron loss of the steel sheet, wherein a cold rolled silicon steel sheet having a final gauge is subjected to a decarburization annealing to form a silica-containing subscale on the surface, coated with an annealing separator consisting mainly of magnesia on the subscale and subjected to a final annealing to form an insulating film, an improvement comprising using a magnesia series annealing separator containing 0.1-10% by weight, calculated as strontium, of at least one strontium compound selected from the group consisting of SrSO 4 , Sr(OH) 2 .8H 2 O, SrCO 3 , and Sr(NO 3 ) 2 , and 0.5-5% by weight, calculated as titanium, of a titanium compound.
Claim 2
Independent Claim
130 words
A method of forming a highly adhesive and uniform insulating film on a grain-oriented silicon steel sheet, without deteriorating the iron loss of the steel sheet, wherein a cold rolled silicon steel sheet having a final gauge is subjected to a decarburization annealing to form a silica-containing subscale on the surface, coated with an annealing separator consisting mainly of magnesia on the subscale and subjected to a final annealing to form an insulating film, an improvement comprising using a magnesia series annealing separator containing 0.1-10% by weight, calculated as strontium, of at least one strontium compound selected from the group consisting of SrSO 4 , Sr(OH) 2 .8H 2 O, SrCO 3 , and Sr(NO 3 ) 2 , and 0.5-5% by weight, calculated as titanium, of a titanium compound.
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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) | 1983-12-30 | 1984-06-30 | 1984-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-30 | 1988-06-30 | 1988-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-30 | 1992-06-30 | 1992-12-30 | $7700.00 | Window Closed / Lapsed |