Armco Steel Corporation

Armco Inc.

James D Evans

Michael H Haselkorn

Dale M Kohler

William R Long, Jr

David C Brewer

A process of providing an inorganic anti-stick coating directly on non-oriented, semi-processed electrical steels by applying to such steels a coating solution containing Al.sup.+++, Mg.sup.++, and H.sub.2 PO.sub.4.sup.- in a specified relative relationship, the concentration of Al.sup.+++, Mg.sup.++, and H.sub.2 PO.sub.4.sup.- comprising 100 parts by weight calculated as Al.sub.2 O.sub.3, MgO and H.sub.3 PO.sub.4, respectively, on a water-free basis. The coating solution may additionally contain from 0 to 150 parts by weight of colloidal silica on a water-free basis. Chromic anhydride (C.sub.r O.sub.3) may be added to the coating solution to improve its wettability and improve the moisture resistance of the anti-stick coating. The coating solution is so diluted with water as to provide a uniform coating as thin as possible to prevent lamination sticking and having a coating weight of less than 2 grams per square meter on each side. The coated electrical steel is subjected to a heat treatment to cure the anti-stick coating thereon.

Method of providing an anti-stick coating on non-oriented,

A method of improving the surface insulation resistance of electrical steels having an insulative coating thereon by subjecting the electrical steels to electrochemical treatment as part of the routing thereof, to remove small metallic nodules, particles and the like extending through or protruding above the insulative coating. Following the electrochemical treatment, the electrical steels are rinsed and dried.

Method of improving the surface insulation resistance of electrical

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.sup.+.sup.+.sup.+, Mg.sup.+.sup.+ and H.sub.2 PO.sub.4.sup.- 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 (CrO.sub.3) 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.

Insulative coating for electrical steels

A melt for cold rolled, non-oriented silicon steel is deoxidized and thereafter treated with mischmetal or a mischmetal alloy to desulfurize the melt to 0.012% by weight sulfur or less without the formation of a polluting smoke. The deoxidation is carried out to the extent that, and the mischmetal is added in an amount such that, the melt composition, has a total cerium content of up to about 400 ppm. and preferably from about 75 to about 250 ppm.

Rare earth metal treated cold rolled, non-oriented silicon steel and

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.sup.+.sup.+.sup.+, Mg.sup.+.sup.+ and H.sub.2 PO.sub.4 .sup.- 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 (CrO.sub.3) 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.

Insulative coatings for electrical steels having improved resistance to deterioration during stress relief anneals or other heat treatments carried on in reducing atmospheres. They may be produced by coating electrical steel with an aqueous solution of phosphoric acid, magnesium oxide and one or more additional mineral acids present in an amount sufficient to adjust the pH level of the solution to from about 0.5 to about 3.0. The mole ratio Mg/PO.sub.4 should be from about 0.6 to about 1.5.

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Middletown, OH, United States of America

James D Evans