# US 8,771,795 B2 · Treatment solution for insulation coating for grain-oriented electrical steel sheets and method for producing grain-oriented electrical steel sheet having insulation coating

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- Number: US 8,771,795 B2
- Document ID: US8771795B2
- Status: Granted
- Kind: B2
- Application number: 12/671,972
- Filed: 2008-07-30
- Published: 2011-09-29
- Granted: 2014-07-08
- Earliest claimed: 2007-08-09
- Assignees: Jfe Steel Corporation
- Applicants: Mineo Muraki; Minoru Takashima; Tomofumi Shigekuni
- Inventors: Mineo Muraki; Minoru Takashima; Tomofumi Shigekuni
- Web page: https://patentgrep.com/patent/US8771795B2

## CPC

- C23C 22/40: containing molybdates, tungstates or vanadates
- C21D 1/70: while heating or quenching
- C21D 8/1283: {Application of a separating or insulating coating}
- C22C 38/60: containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
- C23C 22/68: using aqueous solutions with pH between 6 and 8
- C23C 22/74: for obtaining burned-in conversion coatings
- C23C 26/00: Coating not provided for in groups C23C2/00 - C23C24/00
- H01F 1/18: with insulating coating
- H01F 41/005: {Impregnating or encapsulating (insulating of windings H01F41/12)}
- H01F 41/024: {Manufacturing of magnetic circuits made from deformed sheets (magnetic cores made from deformed sheets H01F27/2455)}
- C21D 2201/05: Grain orientation
- 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)
- 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)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

A treatment solution for insulation coating for grain-oriented electrical steel sheets contains at least one selected from phosphates of Mg, Ca, Ba, Sr, Zn, Al, and Mn; colloidal silica in a proportion of 0.5 to 10 mol in terms of SiO2 and a water-soluble vanadium compound in a proportion of 0.1 to 2.0 mol in terms of V, relative to PO4:1 mol in the phosphates.

## Claims

### Claim 1

A method for producing a grain-oriented electrical steel sheet having an insulation coating, comprising:
hot rolling a slab for grain-oriented electrical steel sheets into a sheet with a thickness of 1.5 to 3.0 mm;
subsequently or after subjecting the sheet to normalizing annealing, subjecting the sheet to cold rolling once, or twice or more including intermediate annealing to obtain a selected sheet thickness,
subjecting the sheet to primary recrystallization annealing at a temperature of 800° C. to 950° C. for ten to 600 seconds,
coating the sheet with an annealing separator containing MgO as a primary component,
subjecting the sheet to secondary recrystallization annealing at a temperature of 800° C. to 1250° C. for five to 600 hours,
coating the sheet with a treatment solution for insulation coating to secure a coating thickness of 1 to 5 μm after baking, and
baking the sheet at a baking temperature of 350° C. or higher,
wherein the treatment solution comprises 1) at least one selected from phosphates of Mg, Ca. Ba, Sr, Zn, Al, and Mn, 2) colloidal silica in a proportion of 0.5 to 10 mol in terms of SiO2 and 3) a water-soluble vanadium compound in a proportion of 0.1 to 2.0 mol in terms of V, relative to PO4:1 mol in the phosphates, and
wherein the water-soluble vanadium compound contains at least one selected from the group consisting of potassium vanadate, ammonium vanadate and vanadium bromide.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the water-soluble vanadium compound is at least one selected from the group consisting of potassium vanadate, ammonium vanadate and vanadium bromide.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the water-soluble vanadium compound is at least one selected from the group consisting of potassium vanadate, ammonium vanadate, and vanadium bromide in a proportion of 0.2 mol or more in terms of V, relative to PO4:1 mol in the phosphates.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the insulation coating has a moisture absorption resistance as measured by elusion of P of 80 μg/150 cm2 or less.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the treatment solution contains substantially no Cr.