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US 6,284,388 B1Granted
Steel with electrically insulating hematite layer
AssigneeLTV Steel Company, Inc.
InventorsRichard J. Blotzer, Jeffrey P. Anderson, Barry A. Lauer
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AssigneeLTV Steel Company, Inc.
InventorsRichard J. Blotzer, Jeffrey P. Anderson, Barry A. Lauer
Estimating the term…
The present invention is directed to a method of forming an electrically insulating layer on a steel article such as a stack of electrical steel laminations or an individual, unstacked electrical steel lamination, comprising exposing the article to an oxidation atmosphere, and to a temperature (such as at least about 800° F.) for a time sufficient to form on the article an electrically insulating layer comprising hematite. The hematite layer is effective to provide the article with a surface resistivity characterized by an F-amp value of not greater than about 0.85 at a test pressure of 50 psi and a transfer surface roughness of about 10 microinches (Ra). Also featured is a steel article having the electrically insulating layer formed thereon.
A method of forming an electrically insulating layer on a steel article comprising the steps of:
A method of treating steel comprising exposing a steel article to an oxidation atmosphere wherein oxygen is present in the oxidation atmosphere and to a temperature for a time so as to form on said article an electrically insulating layer comprising hematite effective to provide said article with a surface resistivity characterized by an F-amp value not greater than about 0.85 at a test pressure of 50 psi and at a transfer surface roughness of about 10 microinches (Ra).
A method of treating a steel lamination stack comprising exposing said stack to an oxidation atmosphere wherein oxygen is present in the oxidation atmosphere and to a temperature for a time so as to form on said article an electrically insulating layer comprising hematite effective to provide said article with a surface resistivity characterized by an F-amp value not greater than about 0.85 at a test pressure of 50 psi and at a transfer surface roughness of about 10 microinches (Ra).
A steel article comprising a stack of laminations having a hematite layer formed onto compressed surfaces of said stack wherein said article has a surface resistivity characterized by an F-amp value not greater than about 0.85 at a test pressure of 50 psi and at a transfer surface roughness of about 10 microinches (Ra).
Dependencies are inferred from the claim text.