US3948786A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Insulative coating for electrical steels
Assignee: Armco Inc
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Filing: 1974-10-11
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Granted: 1976-04-06
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Expires: 1994-10-11
Abstract
Abstract Insulative coatings for electrical steels and methods of making them. The coatings are hard, glassy and smooth in nature, are easily cured and improve the magnetic characteristics of the electrical steels. The coatings are produced by applying to an electrical steel an aluminum-magnesium-phosphate solution containing Al<+++>, Mg<++> and H2PO4<-> in a specified relative relationship and from 0 to 60% by weight colloidal silica on a water-free basis. The solutions contain at least 45% by weight water. Chromic anhydride (CrO3) may be added to the coating solutions to improve wettability of the solutions, moisture resistance of the resulting coatings and interlaminar resistivity after stress relief anneal. An electrical steel coated with a solution of the present invention is thereafter subjected to a heat treatment to cure the insulative coating thereon.
Inventors
- 👤 James D. Evans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:38
CPC Classifications
H; H01; H01B; H01B3/00; H01B3/02; H01B3/08; H01B3/087; C; C23; C23C; C23C22/00; C23C22/73; C23C22/74; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/14; H01F1/147; H01F1/14766; H01F1/14775; H01F1/14783
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
202 words
A coating solution for forming an insulative coating directly on electrical steels and on electrical steels having a mill glass thereon, said solution containing an Al + + + , Mg + + and H 2 PO 4 - concentration in the following relative relationship on a water-free basis: from 3 to 11% by weight Al + + + calculated as Al 2 O 3 , from 3 to 15% by weight Mg + + , calculated as MgO, and from 78 to 87% by weight H 2 PO 4 - calculated as H 3 PO 4 , the total weight percentage of Al + + + (as Al 2 O 3 ), Mg + + (as MgO) and H 2 PO 4 - (as H 3 PO 4 ) being 100% on a water-free basis, said concentration of Al + + + , Mg + + and H 2 PO 4 - comprising 100 parts by weight calculated as Al 2 O 3 , MgO and H 3 PO 4 respectively on a water-free basis, and from 0 to 150 parts by weight of colloidal silica on a water-free basis, at least 45% by weight of said coating solution being water.
Claim 2
Dependent Claim
202 words
A coating solution for forming an insulative coating directly on electrical steels and on electrical steels having a mill glass thereon, said solution containing an Al + + + , Mg + + and H 2 PO 4 - concentration in the following relative relationship on a water-free basis: from 3 to 11% by weight Al + + + calculated as Al 2 O 3 , from 3 to 15% by weight Mg + + , calculated as MgO, and from 78 to 87% by weight H 2 PO 4 - calculated as H 3 PO 4 , the total weight percentage of Al + + + (as Al 2 O 3 ), Mg + + (as MgO) and H 2 PO 4 - (as H 3 PO 4 ) being 100% on a water-free basis, said concentration of Al + + + , Mg + + and H 2 PO 4 - comprising 100 parts by weight calculated as Al 2 O 3 , MgO and H 3 PO 4 respectively on a water-free basis, and from 0 to 150 parts by weight of colloidal silica on a water-free basis, at least 45% by weight of said coating solution being water.
Claim 3
Dependent Claim
35 words
The coating solution claimed in claim 1, including from 10 to 25 parts by weight chromic anhydride for every 100 parts by weight H 2 PO 4 - calculated as H 3 PO 4 .
Claim 4
Dependent Claim
200 words
A coating solution for forming an insulative coating directly on electrical steels and on electrical steels having a mill glass thereon, said solution containing an Al + + + , Mg + + and H 2 PO 4 - concentration in the following relative relationship on a water-free basis: from 3 to 11% by weight Al + + + calculated as Al 2 O 3 , from 3 to 15% by weight Mg + + calculated as MgO and from 78 to 87% by weight H 2 PO 4 - calculated as H 3 PO 4 , the total weight percentage of Al + + + (as Al 2 O 3 ), Mg + + (as MgO) and H 2 PO 4 - (as H 3 PO 4 ) being 100% on a water-free basis, said concentration of Al + + + , Mg + + and H 2 PO 4 -comprising 100 parts by weight calculated as Al 2 O 3 , MgO and H 3 PO 4 respectively on a water-free basis, and from 33 to 150 parts by weight of colloidal silica on a water-free basis, at least 60% by weight of said coating solution being water.
Claim 5
Dependent Claim
200 words
A coating solution for forming an insulative coating directly on electrical steels and on electrical steels having a mill glass thereon, said solution containing an Al + + + , Mg + + and H 2 PO 4 - concentration in the following relative relationship on a water-free basis: from 3 to 11% by weight Al + + + calculated as Al 2 O 3 , from 3 to 15% by weight Mg + + calculated as MgO and from 78 to 87% by weight H 2 PO 4 - calculated as H 3 PO 4 , the total weight percentage of Al + + + (as Al 2 O 3 ), Mg + + (as MgO) and H 2 PO 4 - (as H 3 PO 4 ) being 100% on a water-free basis, said concentration of Al + + + , Mg + + and H 2 PO 4 -comprising 100 parts by weight calculated as Al 2 O 3 , MgO and H 3 PO 4 respectively on a water-free basis, and from 33 to 150 parts by weight of colloidal silica on a water-free basis, at least 60% by weight of said coating solution being water.
Claim 6
Dependent Claim
33 words
The solution claimed in claim 3 including from 10 to 25 parts by weight chromic anhydride for every 100 parts by weight H 2 PO 4 -caluclated as H 3 PO 4 .
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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) | 1979-04-06 | 1979-10-06 | 1980-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-06 | 1983-10-06 | 1984-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-06 | 1987-10-06 | 1988-04-06 | $7700.00 | Window Closed / Lapsed |