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US4130447A Expired / Lapsed US ⏱️ 0.0 years remaining

Annealing separator and steel sheet coated with same

Assignee: TERNI-SOCIETA PER L'INDUSTRIA E L'ELETTRICITA SpA
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Filing: 1977-08-15
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Granted: 1978-12-19
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Expires: 1997-08-15
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Abstract

Abstract An annealing separator for use on grain-oriented silicon steel strip comprises a magnesium oxide base composition containing rare earth metal oxides. The rare earth metal oxides are present in an amount of 0.8 to 30% by weight of the composition; but in the lower range of 0.8 to 5% by weight, and preferably up to 7% by weight, the oxides have a particle size of less than 325 mesh, and a fraction of 35-55% by weight smaller than 500 mesh. Alkali metal silicate may be present in an amount 5 to 45% by weight. Strip coated with annealing separator of the invention is characterized in that the coating is almost totally free of surface cavities, in that the denitriding and desulfuring rates are greatly accelerated, in that the surface resistivity of the coating is substantially increased, and in that the coating adheres more strongly to the strip.

Inventors

  • 👤 Edmondo Marianeschi
  • 👤 Sandro Basevi
  • 👤 Mario Barisoni
  • 👤 Paolo Marini
  • 👤 Carlo Borgianni
  • 👤 Roberto Ricci Bitti

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-24 03:59
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/68; C21D1/70; C23; C23D; C23D5/00; C23D5/10; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12451

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 91 words
Annealing separator compositions for grain-oriented silicon steel strip, said separator compositions having a magnesium oxide base and containing 0.8 to 35% by weight of at least one member selected from the group consisting of rare earth metal oxides and rare earth metal compounds which yield oxides upon heating, with the provision that when said at least one compound is present in an amount between 0.8 and 5% by weight, said compound has a particle size of less than 325 mesh, and a fraction of 35-55% by weight smaller than 500 mesh.
Claim 2
Dependent Claim 91 words
Annealing separator compositions for grain-oriented silicon steel strip, said separator compositions having a magnesium oxide base and containing 0.8 to 35% by weight of at least one member selected from the group consisting of rare earth metal oxides and rare earth metal compounds which yield oxides upon heating, with the provision that when said at least one compound is present in an amount between 0.8 and 5% by weight, said compound has a particle size of less than 325 mesh, and a fraction of 35-55% by weight smaller than 500 mesh.
Claim 3
Dependent Claim 47 words
Annealing separator compositions as claimed in claim 1, with the provision that when said compound is present in an amount 0.8 to 7% by weight, said compound has a particle size of less than 325 mesh, and a fraction of 35-55% by weight smaller than 500 mesh.
Claim 4
Dependent Claim 22 words
Annealing separator compositions as claimed in claim 1, containing 5 to 45% by weight of the separator of an alkali metal silicate.
Claim 5
Dependent Claim 25 words
Annealing separator compositions as claimed in claim 1, in which said compound is present in an amount about 10% by weight, balance essentially magnesium oxide.
Claim 6
Dependent Claim 36 words
Annealing separator compositions as claimed in claim 1, in which said compound is present in an amount 10% by weight, said separator compositions containing about 10% by weight of alkali metal silicate, balance essentially magnesium oxide.
Claim 7
Dependent Claim 22 words
Grain-oriented silicon steel strip coated with an annealing separator composition as claimed in claim 1 to a thickness of about 1-3 μm.

References Cited (Backward Citations)

US2354123A Cited
US2850381A Cited
US3379581A Cited
US3620645A Cited
US3956029A Cited
US3960616A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1981-12-18 1982-06-19 1982-12-19 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1985-12-18 1986-06-19 1986-12-19 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1989-12-18 1990-06-19 1990-12-19 $7700.00 Window Closed / Lapsed

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