# US 11,440,846 B2 · Solution for forming insulation coating and grain-oriented electrical steel sheet

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- Number: US 11,440,846 B2
- Document ID: US11440846B2
- Status: Granted
- Kind: B2
- Application number: 14/766,560
- Filed: 2013-05-27
- Published: 2015-12-24
- Granted: 2022-09-13
- Earliest claimed: 2013-02-08
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Regis Lemaitre; Ludger Lahn; Carsten Schepers; Shuichi Yamazaki; Kazutoshi Takeda; Masaru Takahashi; Hirohiko Sato; Koji Kanehashi
- Web page: https://patentgrep.com/patent/US11440846B2

## CPC

- C04B 28/34: containing cold phosphate binders
- C04B 14/062: {Microsilica, e.g. colloïdal silica (preparing microsilica slurries or suspensions C04B18/148)}
- C21D 8/1283: {Application of a separating or insulating coating}
- C23C 22/08: Orthophosphates
- C23C 22/18: containing manganese cations
- C23C 22/20: containing aluminium cations
- C23C 22/22: containing alkaline earth metal cations
- C23C 22/74: for obtaining burned-in conversion coatings
- H01F 1/18: with insulating coating
- C04B 2111/00525: {for metallic surfaces}
- Y10T 428/249969: Of silicon-containing material [e.g., glass, etc.]
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A solution for forming an insulation coating of grain-oriented electrical steel sheet includes an aqueous solution prepared by mixing a phosphate solution and colloidal silica. Chromium is not added to the aqueous solution. The colloidal silica includes silica particles surface-modified by an aluminate or is prepared by adding an aluminate to colloidal silica such as conventional colloidal silica.

## Claims

### Claim 1

A grain-oriented electrical steel sheet comprising an insulation coating, wherein the insulation coating consists of phosphorous, silicon, oxygen, and at least one selected from Al, Mg, and Mn, the insulation coating is free of chromium, and an area rate of pores in a cross section of the insulation coating is less than 10%.

### Claim 2 (depends on 1)

The grain-oriented electrical steel sheet according to claim 1, wherein the insulation coating includes a chemical structure of phosphorus so that a 31P nuclear magnetic resonance spectrum of the insulation coating shows a 31P chemical shift at −32 to −38 ppm when the 31P chemical shift is referenced to an 85 mass % H3PO4 solution.

### Claim 3 (depends on 2)

The grain-oriented electrical steel sheet according to claim 2, wherein a peak area of the 31P chemical shift at −32 to −38 ppm is more than 30% of a total peak area when the peak area of the 31P chemical shift at −32 to −38 ppm and the total peak area are calculated with a Gaussian fitting in which a peak position is determined in a range of 0 to −60 ppm.

### Claim 4 (depends on 1)

A method for making the grain-oriented electrical steel sheet comprising the insulation coating of claim 1, comprising:
applying a solution comprising an aqueous solution consisting essentially of a phosphate solution and colloidal silica to at least one surface of the steel sheet,
and baking the steel sheet at a temperature of 750-1000° C. to form an insulation coating on the at least one surface of the steel sheet,
wherein silica particles of the colloidal silica are surface-modified by aluminate or a solution of the colloidal silica includes aluminate,
the aqueous solution is free of chromium, and
the insulation coating formed by baking the steel sheet has an area fraction of voids in a cross section of the insulation coating is less than 10%.

### Claim 5 (depends on 4)

The method for forming the insulation coating on a grain-oriented electrical steel sheet according to claim 4,
wherein the phosphate solution includes one or more selected from aluminum phosphate, magnesium phosphate, nickel phosphate, and manganese phosphate.

### Claim 6 (depends on 5)

The method for forming the insulation coating on a grain-oriented electrical steel sheet according to claim 5,
wherein an amount of the phosphate solution is 25-75 mass % and an amount of the colloidal silica is 75-25 mass % of a total solid mass when the amounts of the phosphate solution and the colloidal silica are calculated in anhydrous form.

### Claim 7 (depends on 4)

The method for forming the insulation coating on a grain-oriented electrical steel sheet according to claim 4,
wherein an amount of the phosphate solution is 25-75 mass % and an amount of the colloidal silica is 75-25 mass % of a total solid mass when the amounts of the phosphate solution and the colloidal silica are calculated in anhydrous form.

### Claim 8

A grain-oriented electrical steel sheet comprising an insulation coating formed by:
applying a solution comprising an aqueous solution consisting essentially of a phosphate solution and colloidal silica to at least one surface of the steel sheet, and baking the steel sheet at a temperature of 750-1000° C. to form an insulation coating on the at least one surface of the steel sheet,
wherein silica particles of the colloidal silica are surface-modified by aluminate or a solution of the colloidal silica includes aluminate,
the aqueous solution is free of chromium,
the phosphate solution consists essentially of one or more selected from aluminum phosphate, magnesium phosphate, and manganese phosphate, and
the insulation coating consists of phosphorous, silicon, oxygen, and at least one selected from Al, Mg, and Mn.

### Claim 9 (depends on 8)

The grain-oriented electrical steel sheet according to claim 8, wherein the insulation coating includes a chemical structure of phosphorus so that a 31P nuclear magnetic resonance spectrum of the insulation coating shows a 31P chemical shift at −32 to −38 ppm when the 31P chemical shift is referenced to an 85 mass % H3PO4 solution.

### Claim 10 (depends on 9)

The grain-oriented electrical steel sheet according to claim 9, wherein a peak area of the 31P chemical shift at −32 to −38 ppm is more than 30% of a total peak area when the peak area of the 31P chemical shift at −32 to −38 ppm and the total peak area are calculated with a Gaussian fitting in which a peak position is determined in a range of 0 to −60 ppm.

### Claim 11

A grain-oriented electrical steel sheet comprising an insulation coating formed by:
applying a solution comprising an aqueous solution consisting essentially of a phosphate solution and colloidal silica to at least one surface of the steel sheet, and baking the steel sheet at a temperature of 750-1000° C. to form an insulation coating on the at least one surface of the steel sheet,
wherein silica particles of the colloidal silica are surface-modified by aluminate or a solution of the colloidal silica includes aluminate,
the aqueous solution is free of chromium,
the phosphate solution consists essentially of one or more selected from aluminum phosphate, magnesium phosphate, and manganese phosphate,
an amount of the phosphate solution is 25-75 mass % and an amount of the colloidal silica is 75-25 mass % of a total solid mass when the amounts of the phosphate solution and the colloidal silica are calculated in anhydrous form, and
the insulation coating consists of phosphorous, silicon, oxygen, and at least one selected from Al, Mg, and Mn.

### Claim 12 (depends on 11)

The grain-oriented electrical steel sheet according to claim 11, wherein the insulation coating includes a chemical structure of phosphorus so that a 31P nuclear magnetic resonance spectrum of the insulation coating shows a 31P chemical shift at −32 to −38 ppm when the 31P chemical shift is referenced to an 85 mass % H3PO4 solution.

### Claim 13 (depends on 12)

The grain-oriented electrical steel sheet according to claim 12, wherein a peak area of the 31P chemical shift at −32 to −38 ppm is more than 30% of a total peak area when the peak area of the 31P chemical shift at −32 to −38 ppm and the total peak area are calculated with a Gaussian fitting in which a peak position is determined in a range of 0 to −60 ppm.

### Claim 14

A grain-oriented electrical steel sheet comprising an insulation coating, wherein the insulation coating consists of phosphorous, silicon, oxygen, and at least one selected from Al, Mg, and Mn, the insulation coating is free of chromium and the insulation coating includes a chemical structure of phosphorus so that a 31P nuclear magnetic resonance spectrum of the insulation coating shows a 31P chemical shift at −32 to −38 ppm when the 31P chemical shift is referenced to an 85 mass % H3PO4 solution.