US3930906A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming an insulating glass film on a grain-oriented silicon steel sheet having a high magnetic induction
Assignee: JFE Steel Corp
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Filing: 1975-02-24
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Granted: 1976-01-06
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Expires: 1995-02-24
Abstract
Abstract An insulating glass film having an excellent uniformity and a high adhesion to a grain-oriented silicon steel sheet having a high magnetic induction is formed by annealing a coil of a cold rolled silicon steel sheet having a final gauge in an annealing furnace under a non-oxidizing and non-reducing neutral inert gas, such as nitrogen or argon at a constant temperature keeping stage of 800°-920°C and then under dry hydrogen at a temperature of 1,000°-1,200°C in the final annealing stage.
Inventors
- 👤 Toshio Irie
- 👤 Yasuo Yokoyama
- 👤 Toshitomo Sugiyama
- 👤 Hiroshi Shimanaka
- 👤 Shigeru Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:54
CPC Classifications
C; C21; C21D; C21D3/00; C21D3/02; C21D3/04; C21D1/00; C21D1/74; C21D8/00; C21D8/12; C21D8/1244; C21D8/1272; C23; C23D; C23D5/00; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/14; H01F1/147; H01F1/14766; H01F1/14775; H01F1/14783; C21D8/1277; C21D8/1283
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
186 words
In a method for producing a grain-oriented silicon steel sheet having B 8 value of more than 1.88 Wb/m 2 and provided with a uniform insulating glass film having a high adhesion to a base metal, in which a cold rolled silicon steel sheet having a final gauge is subjected to decarburization annealing under wet hydrogen atmosphere to form an oxide layer consisting mainly of SiO 2 and FeO on the surface of the steel sheet, a separator containing MgO is coated on the decarburization annealed steel sheet, the thus treated sheet is wound into a coil and the coiled sheet is heated by keeping the temperature at 800°-920°C constantly for at least 10 hours to fully develop secondary recrystallized grains of (110) [001] orientation and then raising and keeping the temperature at 1,000°-1,200°C constant to form MgO-SiO 2 glass film on the surface of the steel sheet, the improvement which comprises using a neutral gas inert against iron at least in the above described temperature keeping stage of 800°-920°C and replacing the natural gas with hydrogen gas the above described temperature keeping stage of 1,000°-1,200°C.
Claim 2
Dependent Claim
186 words
In a method for producing a grain-oriented silicon steel sheet having B 8 value of more than 1.88 Wb/m 2 and provided with a uniform insulating glass film having a high adhesion to a base metal, in which a cold rolled silicon steel sheet having a final gauge is subjected to decarburization annealing under wet hydrogen atmosphere to form an oxide layer consisting mainly of SiO 2 and FeO on the surface of the steel sheet, a separator containing MgO is coated on the decarburization annealed steel sheet, the thus treated sheet is wound into a coil and the coiled sheet is heated by keeping the temperature at 800°-920°C constantly for at least 10 hours to fully develop secondary recrystallized grains of (110) [001] orientation and then raising and keeping the temperature at 1,000°-1,200°C constant to form MgO-SiO 2 glass film on the surface of the steel sheet, the improvement which comprises using a neutral gas inert against iron at least in the above described temperature keeping stage of 800°-920°C and replacing the natural gas with hydrogen gas the above described temperature keeping stage of 1,000°-1,200°C.
Claim 3
Dependent Claim
16 words
The method as claimed in claim 1, wherein said silicon steel sheet contains 0.005-0.2% of Sb.
Claim 4
Dependent Claim
22 words
The method as claimed in claim 1, wherein a thickness of the oxide layer formed by the decarburization annealing is 0.5-4.0 μm.
Claim 5
Dependent Claim
26 words
The method as claimed in claim 1, wherein the neutral atmosphere is used from room temperature to the end of the temperature keeping stage of 800°-920°C.
Claim 6
Dependent Claim
28 words
The method as claimed in claim 1, wherein the replacement of the atmosphere from the neutral gas to hydrogen is effected at a temperature of lower than 950°C.
Claim 7
Dependent Claim
22 words
The method as claimed in claim 1, wherein said neutral gas is nitrogen containing less than 100 ppm of 0 2 .
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 |