JPH11236682A - Superlow core loss grain oriented silicon steel sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain a superlow core loss grain oriented silicon steel sheet exceedingly excellent in core loss at a low cost. SOLUTION: On the surface of a grain oriented silicon steel sheet with 0.05 to 0.5 mm sheet thickness subjected to finish annealing, as a base film, an extremely thin film obtd. by finely dispersing one or >= two kinds of nitrides- oxides selected from Fe, Si, Al and B into a film essentially consisting of phosphate and colloidal silica is formed, and moreover, on the surface of the film, a tension insulated film essentially consisting of phosphate and colloidal silica and in which 0.01 to 10 wt.% Si nitrides-oxides are finely dispersed is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-low iron loss unidirectional silicon steel sheet and a method for producing the same, and more particularly, to a method of finishing annealed silicon steel sheet having a surface or a linear concave region of the finish annealed silicon steel sheet. On the surface, as a base coat, Fe, Si, Al is contained in a coat mainly composed of phosphate and colloidal silica.
One or two or more nitrides selected from
An ultra-thin film in which oxides are finely dispersed is formed, and then overlaid on top of it, a tension mainly composed of phosphate and colloidal silica in which Si nitride / oxide is finely dispersed in the film. The purpose of the present invention is to improve the adhesiveness between the surface of the silicon steel sheet and the tensile insulating film by forming an insulating film, thereby achieving further improvement of iron loss characteristics at low cost. .

[0002]

BACKGROUND ART grain oriented silicon steel sheet is mainly being used as transformer cores and other electrical equipment, (represented by ₈ value B) flux density as the magnetization characteristic is high, the iron loss (W
_17/50 ) is required to be low.

In order to improve the magnetic properties of a grain-oriented silicon steel sheet, it is necessary to first align the <001> axis of the secondary recrystallized grains in the steel sheet in the rolling direction, and secondly, to make the final It is necessary to minimize impurities and precipitates remaining in the product.

[0004] For this reason, since NPGoss proposed a basic manufacturing technique by two-stage cold rolling of a grain-oriented silicon steel sheet, a number of improvements have been made to the technique, and the magnetic flux density and the density of the grain-oriented silicon steel sheet have been improved. Iron loss values have improved over the years. Among them, the most typical ones are Sb and MnSe or
JP-B-51-13469 using MnS as an inhibitor, and JP-B-33-4710 and JP-B-40-156 using AlN and MnS as inhibitors.
The method according to 44 JP and Sho 46-23820 Patent Publication, according to these methods B ₈ is now the product is obtained having a high magnetic flux density exceeding 1.88T.

In order to obtain a product having a higher magnetic flux density, Japanese Patent Publication No. 577-14737 discloses a method in which Mo is added to a material in a complex manner.
In Japanese Patent Publication No. 62-42968, Mo is added to the material in a complex manner, and then the quenching treatment is applied after intermediate annealing immediately before the final cold rolling, so that B ₈ has a high magnetic flux density of 1.90 T or more. And iron loss W _17/50 is 1.05 W / kg (product thickness: 0.30m
m) It is disclosed that the following low iron loss can be obtained, but there is still room for improvement in sufficiently reducing iron loss.

[0006] In particular, the demand for reducing power loss as much as possible after the energy crisis of more than ten years ago has been remarkably increased, and accordingly, further improvements in the use of iron core materials are desired. Therefore, in order to minimize eddy current loss, the product thickness was reduced.
Many of those having a thickness of 23 mm (9 mil) or less have come to be used.

[0007] Apart from this, improvements have also been made from the standpoint of insulating coatings on unidirectional silicon steel sheets. In other words, silicon steel sheets currently being commercialized can reduce iron loss by applying tension to the steel sheet by utilizing the difference in the coefficient of thermal expansion between the steel sheet surface and the insulating coating on the forsterite-based undercoat. Magnetostriction is improved. As a typical method for forming such a tension insulating film, a method using a coating liquid containing aluminum phosphate, colloidal silica and chromic anhydride as main components disclosed in Japanese Patent Publication No. 53-28375, and JP-B-56-52117 discloses a method using a coating solution containing magnesium phosphate, colloidal silica and chromic anhydride as main components.

[0008] All of the above-mentioned techniques are mainly metallurgical techniques, but apart from these methods, Japanese Patent Publication No. 57-2252
Irradiation of laser or plasma on the surface of the steel sheet after finish annealing as proposed in Japanese Patent Publication (B. Fukuda, K. Sato,
T.Sugiyama, A.Honda and Y.Ito: Proc. Of ASM Con.
of Hard and Soft Magnetic Materials, 8710-008, (US
A), (1987)), and a method for reducing iron loss by artificially reducing the magnetic domain width by 180 ° (magnetic domain refinement technology) was developed. With the development of this technology, the iron loss of the grain-oriented silicon steel sheet has been significantly reduced. However, this technique has a disadvantage that it cannot withstand annealing at high temperatures, and has a problem that its application is limited to a laminated iron core transformer that does not require strain relief annealing.

In this regard, as a domain refining technique capable of withstanding strain relief annealing, a linear groove is introduced into the surface of a steel sheet after finish annealing of a unidirectional silicon steel sheet, and the demagnetizing effect by the groove is applied to the magnetic domain. Has been industrialized to subdivide the technology (H. Kobayashi,
E.Sasaki, M.Iwasaki and N.Takahashi: Proc.SMM-
8., (1987), P.402). Separately, a method has been developed in which a final cold-rolled sheet of unidirectional silicon steel sheet is subjected to local electrolytic etching to form grooves and subdivide magnetic domains (Japanese Patent Publication No. 8-6140). , Has been industrialized.

Further, apart from the above-described method for producing a silicon steel sheet, as disclosed in JP-B-55-19976, JP-A-57-127749 and JP-A-2-3213,
Amorphous alloys are receiving attention as materials for ordinary power transformers and high-frequency transformers. However, such an amorphous material can provide extremely excellent iron loss characteristics as compared with a normal unidirectional silicon steel sheet, but lacks thermal stability, has a low space factor, and is easy to cut. However, since it is too thin and brittle, there are many practical disadvantages such as a large increase in the cost of assembling the transformer, so that it has not been used in large quantities at present.

[0011] In addition, Japanese Patent Publication No. 52-24499 discloses that a forsterite undercoat formed after finish annealing of a silicon steel sheet is removed, the steel sheet surface is polished, and then the metal surface is plated with metal. A method has been proposed. However, this method has a disadvantage that although a low iron loss can be obtained at a low temperature, the metal is diffused into the silicon steel sheet when subjected to a high temperature treatment, so that the iron loss is rather deteriorated.

In this regard, the inventors have previously disclosed in Japanese Patent Publication No. 63-54767 and the like, as solutions to the above disadvantages.
Si, Mn, Cr, Si, Mn, Cr, etc. are applied on a grain-oriented silicon steel sheet by dry plating (PVD) such as CVD, ion plating and ion implantation.
Ni, Mo, W, V, Ti, Nb, Ta, Hf, Al, Cu, Zr and B
It has been disclosed that an ultra-low iron loss can be obtained by forming one or two or more kinds of tension films selected from nitrides and carbides. This manufacturing method has made it possible to obtain extremely excellent iron loss characteristics as a material for power transformers and high frequency transformers, but nevertheless, it has sufficiently responded to recent demands for low iron loss. It was hard to be there.

Therefore, the present inventors have made a fundamental reexamination from all viewpoints in order to further reduce iron loss as compared with the prior art. That is, the inventor formed one or two or more kinds of tension films selected from various nitrides and carbides on the surface of a grain-oriented silicon steel sheet smoothed in a stable process to form an ultra-low iron loss. In order to obtain a product of the following, from the recognition that a fundamental review from the raw material composition of the unidirectional silicon steel sheet to the final processing step is necessary, from tracking the texture of the silicon steel sheet, Smoothness of steel sheet surface and final CVD and P
Intensive studies were conducted up to the VD processing step. as a result,
The following findings were obtained.

(1) Even if a thin film of ceramic (a TiN film is used as a representative example) coated on a silicon steel sheet is formed to a thickness of 1.5 μm or more, the degree of improvement in iron loss is reduced. In other words, a TiN film having a thickness of 1.5 μm or more can only expect a slight improvement in iron loss, but rather causes a decrease in space factor and magnetic flux density. (2) In this case, the role of TiN is more important in the role of adhesion to the silicon steel sheet, in addition to the addition of tension specific to ceramic. That is, in the transmission electron microscope observation of the cross section of TiN (see Iguchi, Y .: Journal of the Japan Institute of Metals, 60 (1996), pp. 781-786), horizontal stripes of 10 nm are observed, which are caused by the [011] -Corresponds to a 5-atomic layer of Fe atoms. (3) Simultaneous measurement of texture of two layers by X-ray in TiN coating area and chemical polishing area (Y. Inokuti: ISIJ Internationala)
l, 36 (1996), pp. 347-352).
The {200} peak shape is circular. However, the shape of the {200} peak of Fe in the TiN coating region is elliptical, and the silicon steel sheet is strongly tensioned in the [100] _si-steel direction. (4) Tension of TiN thin film (Ichio Iguchi, Kazuhiro Suzuki, Yasuhiro Kobayashi:
Journal of the Japan Institute of Metals, 60 (1996), p.674-678)
At 10 MPa, an improvement in magnetic flux density of about 0.014 to 0.016 T can be expected. (This is equivalent to increasing the degree of Goss orientation integration by about 1 °.)

The above is new findings on ceramic coating. Further, the following findings concerning the surface condition of the ceramic film and the steel sheet have been obtained. (5) When the final cold-rolled silicon steel sheet is subjected to local electrolytic etching to form grooves, and after the secondary recrystallization treatment, the steel sheet surface is smoothed by polishing and then coated with a TiN ceramic film In addition, in addition to the magnetic domain segmentation caused by the demagnetizing field effect caused by the introduced grooves, the core loss is effectively reduced by the addition of tension by the ceramic coating. (6) The effect of reducing iron loss by tension when a concave groove is formed on the surface of a steel sheet before ceramic coating is greater than that of a silicon steel sheet smoothed by ordinary polishing (Japanese Patent Publication No. 3-32889). Gazette). That is, when grooves are introduced, different tension acts on the surface of the silicon steel sheet, and the degree of reduction in iron loss due to tensile tension increases. (7) When the ceramic film is coated on the silicon steel plate having the concave grooves, the effect of reducing iron loss is more effective than the case where the ceramic film is smoothed by ordinary polishing and coated with the ceramic film. (For example, see Japanese Patent Publication No. 63-35686) That is, after introducing a linear groove, and subdividing the magnetic domain by applying the demagnetizing field effect of the groove, a ceramic tension coating is formed, and a further 180 ° is formed. It is more effective to subdivide the main magnetic domain, and an ultra-low iron loss can be obtained. (8) If grooves are formed by performing local electrolytic etching on the final cold-rolled sheet of silicon steel sheet, the surface of the steel sheet after the secondary recrystallization treatment is not smoothed by polishing and the TiN ceramic Even when a film is formed, a considerable iron loss reduction effect is exhibited. In other words, even when the surface is not smoothed by polishing, for example, even when there are small irregularities on the surface due to pickling treatment or the like, a strong tension is applied to the surface of the silicon steel sheet by coating the ceramic film having a small coefficient of thermal expansion. It is possible to add, and thereby the iron loss can be advantageously reduced.

Therefore, based on the above-mentioned new findings, the inventor repeated numerous experiments and studies in order to achieve the intended purpose, and as a result, introduced a silicon steel sheet having a smooth surface and linear grooves. Regardless of the silicon steel sheet, it is possible to reduce the iron loss by using a plurality of types of ceramic tension coatings formed on the surface of the silicon steel sheet, and reducing the coefficient of thermal expansion of the ceramic tension coating as it goes outward. Was found to be extremely effective, and based on this, a unidirectional silicon steel sheet with extremely low iron loss was newly developed (Japanese Patent Application No. 9-328042).
Specification).

The thus obtained grain-oriented silicon steel sheet has an extremely thin ceramic film having excellent adhesion and a tensile film, and is capable of achieving not only an ultra-low iron loss but also an insulating property. Moreover, since it has an excellent space factor, it can be said that it is an ideal silicon steel sheet.

[0018]

However, in order to form such a dense ceramic film, processing in a plasma atmosphere in a high vacuum is indispensable. In such a method, high-speed formation of the ceramic film is required. Since a film could not be formed and the productivity was low, there was a problem that the cost would increase when industrialized.

In addition, separately from this, recently, Patent No. 26624
Nos. 82 and 2664326 each propose a low iron loss unidirectional silicon steel sheet having improved coating adhesion and iron loss by forming a composite film of Al oxide-B oxide on the surface of a smoothed steel sheet. Was done. However, the iron loss value W _17/50 of the silicon steel sheet by this method is 0.77 to
It is only about 0.83 W / kg, and it cannot be said that there is still room for improvement at this ultimate iron loss value despite the thin product thickness. Further, the composite ceramic film of the Al oxide-B oxide system manufactured by this method is not a dense and smooth film as compared with a ceramic film formed using vacuum plasma. Insulating coating of silicon steel sheet has insufficient chemical stability and corrosion resistance,
Problems in terms of water resistance have been pointed out.

Then, based on the above-mentioned new findings, the inventors again examined the surface condition of the silicon steel sheet, and further, a tension insulating film formed on the surface. as a result,
Prior to forming a tension insulating coating mainly composed of phosphate and colloidal silica on the surface of a silicon steel sheet, the coating liquid for the tension insulating coating is diluted with water, and Fe, Si is contained in the diluted liquid. , Al and B are coated thinly with a treatment liquid containing an inorganic compound containing at least one selected from the group consisting of Al and B, and a small amount of an inorganic compound containing Fe or the like is attached to the surface of the steel sheet. When a short-time heat treatment is performed in a neutral atmosphere, an ultra-thin film basically having the same film component as the tensile insulating film is formed, and the inorganic compound containing Fe and the like present in the film has an activity of As a result, the ultra-thin film is formed on the surface of the steel sheet with high adhesion, while the ultra-thin film is formed on the surface of the steel sheet with high adhesion. Since they are of the same quality as the tensile insulating film to be formed, Is also very good,
As a result, it is possible to apply a tensile insulating film having much better adhesion to the surface of the steel sheet than in the past, and thus to produce a unidirectional silicon steel sheet with extremely low iron loss with good productivity and low cost. The fact that it can be manufactured under

Further, according to the study of the present inventors, after forming the above-described ultrathin undercoating, when forming a tension insulating coating mainly composed of phosphate and colloidal silica on the undercoating, A small amount of Si nitride
It has been found that finely dispersing an oxide is more advantageous in improving magnetic properties and adhesion. The present invention is based on the above findings.

That is, the gist of the present invention is as follows. 1. Select from Fe, Si, Al and B in a coating mainly composed of phosphate and colloidal silica as a base coat on the surface of a finish-annealed unidirectional silicon steel sheet with a thickness of 0.05 to 0.5 mm as a base coat. It has an ultra-thin film in which one or two or more types of nitrides / oxides are finely dispersed, and is superimposed on it.
Ultra low iron loss unidirectional silicon steel sheet characterized by having a tension insulating coating mainly composed of phosphate and colloidal silica in which 0.01 to 10 wt% of Si nitride / oxide is finely dispersed in the coating .

2. Finished annealed plate having a thickness of 0.05 to 0.5 mm, a linear concave region having a width of 50 to 500 μm and a depth of 0.1 to 50 μm at intervals of 2 to 10 mm in a direction intersecting the rolling direction and having a width of 50 to 500 μm. On the surface of a grain-oriented silicon steel sheet, as a base coat, a coating mainly composed of phosphate and colloidal silica contains Fe, Si,
An ultra-thin film in which one or two or more types of nitrides and oxides selected from Al and B are finely dispersed is provided, and is superposed thereon to form a nitride film of 0.01 to 10 wt% of Si. An ultra-low iron loss unidirectional silicon steel sheet having a tension insulating coating mainly composed of phosphate and colloidal silica in which oxides are finely dispersed.

3. On the surface of finish-annealed unidirectional silicon steel sheet with a thickness of 0.05 to 0.5 mm, Fe, Si, Al
One or two or more nitrides selected from
An ultra-thin film with finely dispersed oxide is provided and superimposed on it. The main component is phosphate and colloidal silica with finely dispersed 0.01 to 10 wt% Si nitride / oxide in the film. An ultra-low iron loss, further comprising a tension insulating film having a tension insulating film mainly containing phosphate and colloidal silica not containing nitride and oxide as described above. Oriented silicon steel sheet.

4. Finished annealed plate having a thickness of 0.05 to 0.5 mm, a linear concave region having a width of 50 to 500 μm and a depth of 0.1 to 50 μm at intervals of 2 to 10 mm in a direction intersecting the rolling direction and having a width of 50 to 500 μm. On the surface of a grain-oriented silicon steel sheet, as a base coat, a coating mainly composed of phosphate and colloidal silica contains Fe, Si,
An ultra-thin film in which one or two or more types of nitrides and oxides selected from Al and B are finely dispersed is provided, and is superposed thereon to form a nitride film of 0.01 to 10 wt% of Si. A tension insulating coating mainly composed of phosphate and colloidal silica in which oxides are finely dispersed, and a normal phosphate and colloidal silica not containing nitride and oxide as described above as main components. An ultra-low iron loss unidirectional silicon steel sheet having a tension insulating film.

[5] In 1, 2, 3 or 4, the ultra-low iron loss unidirectional silicon steel sheet wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface subjected to a smoothing treatment.

6. The ultra low iron loss unidirectional silicon steel sheet as described in any one of the above 1, 2, 3 and 4, wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface that has not been subjected to a smoothing treatment and is still pickled.

7. A coating solution for a tensile insulating coating mainly composed of phosphate and colloidal silica is diluted with water on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment liquid containing a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B, a small amount of Fe, Si, Al and B After attaching an inorganic compound containing one or two or more kinds selected from the above, a short-time heat treatment is performed in a non-oxidizing atmosphere, and Fe, Si, Al and B. An ultra-thin undercoat is formed by finely dispersing one or more kinds of nitrides / oxides selected from B. Then, a tension insulation mainly composed of phosphate and colloidal silica is formed thereon. Apply and bake a treatment solution containing Si chloride in the coating solution for coating. It the method for producing a ultra-low core loss grain oriented silicon steel sheet, which comprises HiNaru the 0.01-10 wt% of the tension insulating coatings nitride oxide was finely dispersed in the Si in the coating to attach.

8. Finished annealed plate having a thickness of 0.05 to 0.5 mm, a linear concave region having a width of 50 to 500 μm and a depth of 0.1 to 50 μm at intervals of 2 to 10 mm in a direction intersecting the rolling direction and having a width of 50 to 500 μm. The surface of a grain-oriented silicon steel sheet is diluted with water with a coating solution for a tensile insulating film mainly composed of phosphate and colloidal silica, and the diluted solution is selected from Fe, Si, Al and B. By applying and drying a treatment liquid containing a trace amount of an inorganic compound containing at least one species or two or more, an inorganic material containing one or more selected from trace amounts of Fe, Si, Al and B on the steel sheet surface After adhering the compound, a short-time heat treatment is performed in a non-oxidizing atmosphere, and one or two or more kinds selected from Fe, Si, Al and B are included in the coating component on the surface of the steel sheet. An ultra-thin undercoat with finely dispersed nitride / oxide is applied, and then phosphate and By coating and baking a treatment solution containing Si chloride in a coating solution for tensile insulation film mainly composed of idal silica, 0.01 to 10 wt% of Si is nitrided in the film.
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising forming a tension insulating film in which an oxide is finely dispersed.

9. A coating solution for a tensile insulating coating mainly composed of phosphate and colloidal silica is diluted with water on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment liquid containing a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B, a small amount of Fe, Si, Al and B After attaching an inorganic compound containing one or two or more kinds selected from the above, a short-time heat treatment is performed in a non-oxidizing atmosphere, and Fe, Si, Al and B. An ultra-thin undercoat is formed by finely dispersing one or more kinds of nitrides / oxides selected from B. Then, a tension insulation mainly composed of phosphate and colloidal silica is formed thereon. Apply and bake a treatment solution containing Si chloride in the coating solution for coating. By applying, a tensile insulating film in which 0.01 to 10 wt% of Si nitride / oxide is finely dispersed in the film is formed, and further, phosphate and colloidal silica are mainly formed thereon according to a conventional method. A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising forming a normal tensile insulating film to be formed.

10. A linear concave region having a thickness of 0.05 to 0.5 mm, a width of 50 to 500 μm, and a depth of 0.1 to 50 μm was provided at intervals of 2 to 10 mm in a direction intersecting with the rolling direction at intervals of 2 to 10 mm. On the surface of the finish-annealed unidirectional silicon steel sheet, a coating solution for a tensile insulating film mainly composed of phosphate and colloidal silica is diluted with water, and the diluted solution contains Fe, Si, Al and B. By applying and drying a treatment liquid containing a small amount of an inorganic compound containing one or more selected from the group, one or two selected from trace amounts of Fe, Si, Al and B on the steel sheet surface. After attaching an inorganic compound containing at least one kind, a short-time heat treatment is performed in a non-oxidizing atmosphere, and one type selected from Fe, Si, Al and B in a film component on the surface of the steel sheet. Alternatively, an ultra-thin undercoat in which two or more types of nitrides / oxides are finely dispersed is formed, and By the treatment liquid having added thereto a chloride of Si baked coating and the tension insulating coating liquid for coating mainly the phosphate and colloidal silica, and nitriding of 0.01-10 wt% of Si in the film
Forming a tension insulating film in which oxides are finely dispersed, and further forming a normal tensile insulating film containing phosphate and colloidal silica as main components in accordance with a conventional method. A method for producing a low iron loss unidirectional silicon steel sheet.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the process that led to success according to the present invention will be described. C: 0.071 wt%, Si: 3.42 wt%, Mn:
0.075 wt%, Se: 0.020 wt%, Sb: 0.025 wt%, Al: 0.
A continuous cast slab containing 020 wt%, N: 0.0076 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1350 ° C for 5 hours and then hot-rolled. This was a hot-rolled sheet having a thickness of 2.0 mm. After subjecting this hot-rolled sheet to uniform annealing at 1000 ° C. for 3 minutes, intermediate annealing at 1050 ° C. is performed.
Rolling was performed twice to obtain a final cold-rolled sheet having a sheet thickness of 0.23 mm.

Thereafter, the final cold-rolled sheet was processed as follows. On the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd-based resin as a main component is subjected to gravure offset printing so that a non-applied portion has a width of approximately 200 at right angles to the rolling direction.
The coating was performed so as to remain in a linear shape at a distance of 4 mm and baked at 200 ° C. for 3 minutes. At this time, the resist thickness was 2 μm. By performing electrolytic etching on the steel sheet coated with the etching resist in this way,
A linear groove having a width of 200 μm and a depth of 20 μm was formed, and then immersed in an organic solvent to remove the resist. At this time, the current density in the electrolytic etching was 10 A / d in a NaCl electrolytic solution.
m ² , treatment time: 20 seconds. For comparison, a silicon steel sheet not subjected to these treatments was also prepared.

Thereafter, these steel sheets were subjected to decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., and then CaO (30
%), Al ₂ O ₃ (60%), SiO ₂ (10%), and the slurry is coated with an annealing separator, then annealed at 850 ° C for 15 hours, and then at a rate of 850 ° C to 10 ° C / h. After heating to 1080 ° C to develop secondary recrystallized grains strongly integrated in Goss orientation,
Purification was performed in dry H ₂ at ° C.

After removing the surface coating of the product thus obtained and then smoothing the surface of the silicon steel sheet by chemical polishing, the following three treatments were performed. (A) Dilute 250 cc of a coating solution for tension insulating coating mainly composed of phosphate and colloidal silica with 1500 cc of distilled water, and further add 15 cc of SiCl ₄ solution and AlP
The silicon steel sheet was immersed in a treatment liquid at 80 ° C. to which 5 g of O _{4 and} 5 g of H ₃ BO ₃ were added in combination, washed with water and dried. (B) Coating solution for tension insulating coating containing phosphate and colloidal silica as main components: immersing a silicon steel plate in a treatment solution of 250 cc diluted with 1500 cc of distilled water at 80 ° C for 20 seconds and washing with water Dried. (C) A coating solution for a tensile insulating film mainly composed of phosphate and colloidal silica: 250 cc diluted with 1500 cc of distilled water, and further added with 25 cc of a SiCl ₄ solution in the diluted solution at 80 ° C. A silicon steel plate was immersed in the solution for 20 seconds, washed with water and dried.

Thereafter, the treated silicon steel sheets (A) and (B) were treated in an N ₂ (50%) + H ₂ (50%) mixed gas at 950 ° C. for 10 minutes. On the other hand, such heat treatment was not performed on the silicon steel sheet treated in (c). Thereafter, a coating liquid for a tension insulating film containing phosphate and colloidal silica as main components: 250
After coating and drying the treatment solution obtained by adding 10~100cc the SiCl ₄ in cc, baked at ₂ gas of 800 ° C. N, tension insulation coating nitride oxide of Si in the film was finely dispersed (film Thickness: about 1-2 μm). Further, for some of the samples, a normal tensile insulating film mainly composed of phosphate and colloidal silica (film thickness: about 2 μm
).

The iron loss characteristics W of each product thus obtained
_17/50 (W / kg), the results of investigation on adhesion and corrosion resistance are summarized in FIG. In addition, the adhesiveness was evaluated based on the diameter that did not peel even after 180 ° bending deformation. In addition, the corrosion resistance was evaluated by performing a salt spray test in 5% NaCl (45 ° C.) for 30 days and evaluating the state of rust on the surface of the silicon steel sheet. The one that caused the error was defined as "bad".

As is apparent from the results shown in FIG.
When the undercoating according to the present invention of step (A) is applied,
Under both conditions, iron loss, adhesion and
Can manufacture ultra-low core loss unidirectional silicon steel sheet with excellent corrosion resistance
It turns out that it is noh. That is, the surface of the silicon steel sheet is chemically
After smoothing by polishing, such a steel plate is
Coating for tension insulation coating mainly composed of colloidal silica
The working solution is diluted with distilled water.
Immersed in a treatment solution containing an inorganic compound containing Si, Al, and B
After the stacking process, the steel sheet is annealed in a non-oxidizing atmosphere
Finely disperse nitride, oxide such as Fe, Al, B on the surface of
An ultra-thin undercoat, and then apply a tension
1 to 30 cc of SiCl in coating liquid for edge coating (250 cc)_Four
After applying, drying and baking,
Tensile insulation coating with finely dispersed Si nitride / oxide in the film
Products coated with a film or a coat for tensile insulation coating
1 to 50 cc of SiCl in the_FourAnd apply
After the cloth is dried, it is baked to nitride Si in the coating.
・ Tension insulation film with oxide finely dispersed
In addition, products coated with a normal tensile insulation coating are
The gap is also iron loss W _17/50But with extremely low iron loss of 0.6 W / kg or less
It is noted that excellent adhesion and corrosion resistance are obtained.
You.

In this regard, the silicon steel sheet in the step (B) is immersed in a treatment liquid obtained by simply diluting a coating liquid for a tension insulating film mainly composed of phosphate and colloidal silica with distilled water. , Annealed in a non-oxidizing atmosphere,
When an undercoating film containing no nitride or oxide such as Fe, Si, Al, or B is formed, although considerable magnetic properties can be obtained by chemical polishing, the coating film is baked during the formation of a tensile insulating film. Since peeling occurs, it cannot be used as a silicon steel sheet.

Similarly, in the step (C), the silicon steel sheet is diluted with distilled water in a coating solution for a tension insulating film mainly composed of phosphate and colloidal silica, and a small amount of SiCl ₃ is added to the diluted solution. Although the treatment of immersion in the treatment liquid to which the inorganic compound containing is added is performed, but if the subsequent annealing treatment in a non-oxidizing atmosphere is not performed, although considerable magnetic properties can be obtained by chemical polishing, The film cannot be used as a silicon steel sheet because the film is peeled off by the baking process at the time of forming the tension insulating film.

Next, FIGS. 2 and 3 show a conventional unidirectional silicon steel sheet (FIGS. 2A and 2B) and a unidirectional silicon steel sheet according to the present invention (FIGS. 3A and 3B). 3) shows a comparison of the coating structure of FIG.
In FIG. 2A, a tension insulating coating mainly composed of phosphate and colloidal silica is simply coated on the surface of a finish-annealed unidirectional silicon steel sheet as disclosed in JP-A-5-311353. In this case, the adhesion between the silicon steel sheet and the insulating film becomes a major problem, and it is difficult to use the product as a practical product. FIG. 2B shows that the surface of a grain-oriented unidirectional silicon steel sheet as disclosed in JP-B-63-35686 is coated with TiN or Cr by CVD or PVD.
This is a case where an ultra-thin ceramic film such as N is formed, and then a tensile insulating film is further formed on the surface. In this case, although it is very effective in reducing iron loss, as described above, Since the plasma treatment in a vacuum is required, there is a disadvantage that the cost is increased.

On the other hand, in the example of the invention shown in FIGS. 3A and 3B, a small amount of Fe, S is present at the interface between the silicon steel sheet and the tensile insulating film.
An ultra-thin undercoat with finely dispersed nitrides and oxides such as i, Al, and B is formed to ensure adhesion to the steel plate and a small amount of special coating in the insulating coating that can apply tension. Since the component is contained, it is considered that the tension is more effectively applied. That is, in the present invention, the undercoat is firmly adhered to the silicon steel ground iron by finely dispersing nitride / oxide such as Fe, Si, Al and B in the ultra-thin undercoat. Since the main component of this undercoat is the same as that of the tension insulating film formed thereon, the adhesion between the undercoat and the overcoat tension insulating film is also good. Therefore, by interposing such an undercoat, the overcoat tension is increased. The tension imparting function of the insulating coating can be fully exhibited, and the nitrided oxide of Si, which enhances the effect of applying tension, is finely dispersed in this overcoated tension insulating film. Is remarkably improved, and as a result, a further iron loss improvement effect is achieved.

In the place shown in FIG. 3, FIG.
Corresponds to step (A)-in FIG. 1 of this experiment. In this case, the corrosion resistance
l _4: completely there is no problem until the addition of about 1~20cc. FIG. 2 (b) corresponds to the step (A)-in FIG. 1 of the present experiment. In this case, the corrosion resistance is lower than that of the inner layer since the outermost layer is covered with a normal tensile insulating film. When forming the tension insulating film on the side, the SiCl ₄ :
It can be seen that there is no problem up to the addition of about 1 to 50 cc.

As is apparent from the above description, the coating structure of the present invention can be said to be a coating having a gradient function with respect to the adhesion between the silicon steel sheet and the tension insulating coating. In the industrial production of the silicon steel sheet according to the present invention, FIG.
As shown in (b) above, there is no cost increase and the coating thickness can be reduced, so that it is much cheaper than before,
Moreover, there is an advantage that the processing can be performed efficiently.

As a prior art of this kind, Japanese Patent Application Laid-Open
No. 131976, JP-A-6-184762 and JP-A-9-78252
In each of the publications, there is proposed a method of forming an oxide layer of an external oxidation type SiO ₂ film on a polished silicon steel sheet surface. However, the gist of these methods is a subscale mainly composed of SiO ₂ by a treatment in wet H ₂ at the time of decarburization and primary recrystallization annealing performed to remove harmful carbon of a silicon steel sheet. Is similar to the formation of In particular, the method of utilizing SiO ₂ obtained by such oxidation treatment of a steel sheet,
It has already been pointed out that the effect of reducing the iron loss due to the mirror finishing of the silicon steel sheet is severely killed.

[0046]

The silicon-containing steel used as the material of the present invention is compatible with any of the conventionally known component compositions, but typical compositions are as follows. C: 0.01 to 0.08 wt% If the content of C is less than 0.01 wt%, the suppression of hot rolled texture is insufficient and large elongated grains are formed, thereby deteriorating the magnetic properties. Since it takes a long time to decarburize in the charcoal process and is not economical, it is preferable to set the content to about 0.01 to 0.08 wt%.

Si: 2.0 to 4.0 wt% If the content of Si is less than 2.0 wt%, sufficient electric resistance cannot be obtained, so that eddy current loss increases and iron loss deteriorates.
If the content is more than wt%, brittle cracks are likely to occur during cold rolling, so it is preferable to be in the range of about 2.0 to 4.0 wt%.

Mn: 0.01 to 0.2 wt% Mn is an important component that determines MnS or MnSe as a dispersed precipitation phase that affects secondary recrystallization of a unidirectional silicon steel sheet. If the amount of Mn is less than 0.01% by weight, the absolute amount of MnS or the like necessary for causing secondary recrystallization becomes insufficient, causing incomplete secondary recrystallization and increasing the number of surface defects called blisters. On the other hand, if the content exceeds 0.2 wt%, even if dissociated solid solution of MnS or the like is performed in slab heating or the like, the dispersed precipitate phase precipitated during hot rolling is likely to be coarse, and the optimal size distribution desired as an inhibitor is impaired. Therefore, Mn is preferably set to about 0.01 to 0.2 wt%.

S: 0.008 to 0.1 wt%, Se: 0.003 to 0.1
wt% S and Se are each 0.1 wt% or less, and S is 0.0
Preferably, the content of Se is in the range of 08 to 0.1 wt%, and the content of Se is in the range of 0.003 to 0.1 wt%. The reason is that if these contents exceed 0.1 wt%, the hot and cold workability deteriorates, and if they do not reach the lower limits, respectively, there is no particular effect on the primary grain growth suppressing function as MnS and MnSe. It is. In addition, the composite addition of Al, Sb, Cu, Sn, B and the like, which are conventionally known as inhibitors, does not hinder the effects of the present invention.

Next, the manufacturing process of the ultra-low iron loss unidirectional silicon steel sheet according to the present invention will be described. First, in order to smelt the raw material, not only an LD converter, an electric furnace, an open hearth furnace, and other known steelmaking furnaces can be used, but also vacuum melting and RH degassing can be used together.

According to the present invention, S, Se contained in the material
Alternatively, as a method of adding a small amount of another primary grain growth inhibitor to molten steel, any conventionally known method may be used. For example, LD converter, RH degassing at the end of molten steel or at the time of ingot casting Can be added. In slab production, it is advantageous to use the continuous casting method because of economic and technical advantages such as cost reduction and uniformity of components or quality in the slab longitudinal direction. It does not hinder.

The continuously cast slab is heated to a temperature of 1300 ° C. or more in order to dissociate and form a solid solution of the inhibitor in the slab. Thereafter, the slab is subjected to hot rough rolling and then hot finish rolling to form a hot-rolled sheet having a thickness of usually about 1.3 to 3.3 mm.

Next, the hot-rolled sheet is subjected to hot-rolled sheet annealing (also referred to as homogenizing annealing) in a temperature range of about 850 to 1100 ° C. as necessary, and then is subjected to one or two cold-pressing steps including intermediate annealing. Rolling is performed to obtain a final thickness, but in order to obtain a product having high magnetic flux density and low iron loss, attention must be paid to the final cold rolling rate (normally 55 to 90%). At this time, the upper limit of the product thickness is 0.5 from the viewpoint of minimizing the eddy current loss of the silicon steel sheet.
mm, and the lower limit of the plate thickness was limited to 0.05 mm in order to avoid the adverse effect of hysteresis loss.

When forming a linear groove on the surface of the steel sheet,
It is particularly advantageous to carry out the process on a steel sheet which has finished the final cold rolling and has a product thickness. That is, on the surface of the final cold-rolled sheet or the steel sheet before and after the secondary recrystallization, the width: 50 to 500 μm, the depth: 0.1 at intervals of 2 to 10 mm in a direction crossing the rolling direction.
That is, a linear concave region of about 50 μm is formed. Here, the interval between the linear concave regions is limited to the range of 2 to 10 mm. If it is less than 2 mm, the unevenness of the steel sheet is too remarkable, the magnetic flux density is lowered and it is not economical. This is because the conversion effect is reduced. If the width of the concave region is less than 50 μm, it will be difficult to use the demagnetizing effect, while if it exceeds 500 μm, the magnetic flux density will decrease and it will not be economical, so the width of the concave region will be in the range of 50 to 500 μm. Limited to. Furthermore, if the depth of the concave region is less than 0.1 μm, the demagnetizing effect cannot be effectively used.
If the thickness exceeds 50 μm, the magnetic flux density decreases and it becomes not economical. Therefore, the depth of the concave region is limited to the range of 0.1 to 50 μm. In addition, the forming direction of the linear concave region is optimally set to a direction perpendicular to the rolling direction, that is, the sheet width direction, but substantially the same effect can be obtained as long as it is within ± 30 ° with respect to the sheet width direction. .

Further, as a method of forming the linear concave region,
On the surface of the final cold-rolled sheet, an etching resist is applied by printing, after baking, an etching process is performed, and then the method of removing the resist is compared with a method using a conventional knife edge or a laser, This is advantageous in that it can be carried out industrially stably, and that iron loss can be more effectively reduced by tensile tension.

Hereinafter, a typical example of the above-described linear groove forming technique by etching will be specifically described. An etching resist ink containing an alkyd resin as a main component is gravure offset printed on the surface of the final cold-rolled sheet so that the non-applied portion remains linearly at a right angle to the rolling direction with a width of 200 μm and a spacing of 4 mm in a line. After applying, bake at 200 ° C for about 20 seconds. At this time, the resist thickness is about 2 μm.
The steel plate coated with the etching resist in this way,
By performing electrolytic etching or chemical etching, a linear groove having a width of 200 μm and a depth of 20 μm is formed.
Next, the resist is removed by immersion in an organic solvent. The electrolytic etching conditions at this time are as follows:
10 A / dm ² , treatment time: about 20 seconds, and chemical etching conditions: immersion time in HNO ₃ solution: about 10 seconds.

Next, the steel sheet is subjected to decarburization annealing. This annealing makes the cold rolled structure the primary recrystallized structure,
{110} <00 in final annealing (also called finish annealing)
1) For the purpose of removing harmful carbon when secondary recrystallized grains having an orientation are developed, the process is performed in, for example, 750 to 880 ° C. in wet hydrogen.

The final annealing is performed to sufficiently develop secondary recrystallized grains having a {110} <001> orientation.
Usually, it is carried out by immediately raising the temperature to 1000 ° C. or higher by box annealing and maintaining the temperature. This final annealing is usually performed by applying an annealing separating agent such as magnesia, and a base coat called forsterite is simultaneously formed on the surface. However, in the present invention, even if a forsterite undercoat is formed, an annealing separator that does not form such a forsterite undercoat is more advantageous because the undercoat is removed in the next step. That is, to reduce the content ratio of MgO to form a forsterite base coating (hereinafter 50%), CaO not to form a Kakaru replace _{film, Al 2 O 3, CaSiO 3} , high content of SiO ₂ or the like (50% The annealed separator described above is advantageous.

In the present invention, in order to develop a secondary recrystallized structure highly integrated in the {110} <001> orientation, it is more advantageous to carry out the constant annealing at a low temperature of 820 ° C. to 900 ° C. For example, slow annealing at a heating rate of about 0.5 to 15 ° C./h may be used.

After this purification annealing, the forsterite undercoat or oxide film on the surface of the steel sheet is removed by a known chemical method such as pickling, a mechanical method such as cutting and polishing, or a combination thereof, and the surface of the steel sheet is removed. Is smoothed. That is, after removing various coatings on the steel sheet surface, chemical polishing,
The surface of the steel sheet is smoothed to a center line average roughness Ra of about 0.4 μm or less by a conventional method such as chemical polishing such as electrolytic polishing or mechanical polishing such as buff polishing or a combination thereof.

In the present invention, it is not always necessary to smooth the surface of the silicon steel sheet. Therefore, in this case, there is an advantage that a sufficient iron loss reducing effect can be exerted only by the pickling treatment without performing the smoothing treatment accompanied by the cost increase. Nevertheless, it is still advantageous to perform the smoothing process. At this stage, a concave groove can be introduced into the surface of the steel sheet. The grooves may be introduced by the same method as that used for the surface of the final cold-rolled sheet or the steel sheet before and after the secondary recrystallization.

After the above treatment, prior to forming a tension insulating coating mainly composed of phosphate and colloidal silica on the steel sheet surface, Fe, Si, An ultra-thin film in which one or two or more kinds of nitrides / oxides selected from Al and B are finely dispersed is formed. In order to form this ultra-thin undercoat, first, a coating solution for a tension insulating film mainly composed of phosphate and colloidal silica is diluted with water, and the diluted solution is added to the diluted solution.
A treatment liquid to which a trace amount of an inorganic compound containing one or more selected from Fe, Si, Al and B is added is used. When applying the treatment liquid to the surface of the steel sheet, the treatment liquid may be applied directly to the surface of the silicon steel sheet.
After applying an aqueous solution to which an inorganic compound such as e, Si, Al, and B is added to the surface of the steel sheet, the treatment liquid may be applied.

Here, as a coating solution for a tension insulating film containing phosphate and colloidal silica as main components, for example, as disclosed in JP-B-53-28375, colloidal silica: 4 to 16 wt%, phosphorus Aluminum oxide: 3-24wt
%, Chromic anhydride and / or chromate: 0.2-4.
Coating liquid containing 5 wt%, colloidal silica: 7 to 24 wt% as disclosed in JP-B-56-52117,
Magnesium phosphate: 5 to 30 wt% (however, the molar ratio of magnesium phosphate to colloidal silica: 20/80 to 30 /
70), and, if necessary, a coating liquid to which chromic anhydride, chromate and / or dichromate: 0.01 to 5% by weight is advantageously applied.

The degree of dilution of the coating liquid is about 1 to 60%, preferably 10 to 20% (for example, 15 to 20%).
It is preferable to dilute the solution to the extent that 100 to 1000 cc of the coating solution is dissolved in a 00 cc aqueous solution). That is, in the present invention, in order to form an undercoat film firmly adhered to the base iron, Fe,
It is necessary to convert inorganic compounds such as Si, Al, and B into nitrides and oxides. However, if the concentration of the underlayer treatment solution is too high, the treatment atmosphere (preferably N ₂ (50%) + H ₂ (50%) mixed gas atmosphere), it is difficult to convert inorganic compounds into nitrides / oxides well, and it is effective to dilute with an appropriate amount of water to effectively promote such nitridation / oxidation. is there.

Further, a selection is made from among Fe, Si, Al and B.
In a diluted solution of an inorganic compound containing one or more
Addition amount of inorganic compound is about 5 to 500 g
(About 0.001 to 0.5 mol / l). When
This is because if the amount of these inorganic compounds is too small,
If the effect cannot be achieved,
Is not only economical, but does the coating properties deteriorate instead?
It is. Here, among the various inorganic compounds described above, Fe
FeCl as an inorganic compound containing_Three, Fe (NO_Three)_ThreeEtc. include Si
SiCl as an inorganic compound_Four, Na_TwoSiO_ThreeEtc. containing Al
AlCl as the organic compound_Three, Al (NO_Three)_Three, AlPO_FourEtc. include B
H as an inorganic compound_ThreeBO _Three, Na_TwoB_FourO₇Etc. are particularly advantageous
Complies with

The above-mentioned treatment liquid obtained by adding a small amount of an inorganic compound such as Fe, Si, Al and B to a diluting liquid of a coating liquid for a tension insulating film as described above is applied to a steel sheet surface and dried. Traces of Fe, Si, Al and B on the surface
After attaching inorganic compounds such as Fe, Si, Al, B and other nitrides and oxides to the surface of the steel plate, a short heat treatment is applied in a non-oxidizing atmosphere. To form an ultra-thin undercoating dispersed in

Here, as a coating method, in addition to coating with a normal roll coater or the like, a dipping method in which the steel sheet itself is immersed in a processing liquid, a method in which the processing liquid is directly sprayed or sprayed on the steel sheet surface, and an electrolytic processing method Any known method such as the method can be used. The treatment temperature may be normal temperature, but it is preferable to perform the treatment in a warm solution of about 50 to 100 ° C. for more effective adhesion. When immersion treatment is used, the immersion time is desirably about 1 to 100 seconds.

Then, after washing with water and drying, fine
In order to form nitrides and oxides such as Fe, Si, Al and B at the interface of the steel sheet, heat treatment is performed for a short time in a non-oxidizing atmosphere. The processing atmosphere is N-containing to promote nitriding.
It is preferable to use a non-oxidizing atmosphere, for example, (N ₂ +
H ₂ ) Mixed gas atmosphere and including ammonia (NH ₃ + H ₂ )
A mixed atmosphere is particularly preferred. The processing temperature is 5
About 00 to 1200 ° C (preferably about 800 to 1000 ° C), processing time about 1 to 100 minutes (preferably about 3 to 30 minutes)
Is preferred.

Thus, the finely dispersed Fe,
Due to the presence of nitrides / oxides such as Si, Al and B, it is possible to form an ultra-thin undercoat firmly adhered to the surface of the steel sheet. The coating amount of the undercoating liquid is preferably in a 0.01 to 0.5 g / m ² approximately, by the heat treatment was coated the amount of this extent, ultimately to 0.001 to 3.0 [mu] m about suitable thickness Thus, an extremely thin undercoating can be obtained.

Thereafter, a tension insulating coating mainly composed of colloidal silica and phosphate was formed on the surface of the silicon steel sheet (0.5%).
In this case, the chloride of Si is added to the coating solution for the tensile insulating film, which is the processing solution, and the nitride / oxide of Si is finely dispersed in the formed tensile insulating film. It is important that Here, the amount of the Si chloride to be added is, for example, when a SiCl ₄ solution is used as the Si chloride, the coating solution for the tension insulating film: 250 cc,
it is preferable to add about 1~20cc of LiCl _4, a nitride-oxide of any case 0.01-10 wt% of Si also in the coating film important to be finely dispersed. This is because if the amount of Si nitride / oxide in the coating is less than 0.01% by weight, the effect on reduction of iron loss and improvement of adhesion is small.
If the content exceeds wt%, corrosion resistance becomes a problem.

In the formation of the undercoat film described above, Fe, S added to the coating solution for the tensile insulating film was used.
In order to convert inorganic compounds such as i, Al, and B into nitrides / oxides, it was essential to dilute the coating solution with water. This is because, during the subsequent heat treatment, it is necessary to add a certain amount of hydrogen gas to the treatment atmosphere so that adverse effects such as nitriding do not occur (N ₂ +
H ₂ ) The mixed gas atmosphere is advantageously adapted, but this (N ₂ +
H ₂ ) The nitriding power is not so strong in the mixed gas atmosphere, and the nitriding / oxidation reaction was not sufficiently promoted with the use of a thick coating solution. However,
In forming the tension insulating film, a pure N ₂ atmosphere can be used, and under this atmosphere, Si chloride can be easily changed to Si nitride / oxide, so that there is no need to particularly dilute the processing solution.

Further, in the present invention, as shown in FIG. 3B, a normal tension insulating film can be further formed thereon. In this case, it is not necessary to consider the corrosion resistance of the underlying tensile insulating film containing Si nitride / oxide, so the amount of SiCl ₄ to be added to the processing solution is shown in FIG.
More than in case (a), the amount can be increased to about 50 cc. The baking temperature at the time of film formation is preferably about 800 to 1000 ° C.

The film thickness of these tension insulating films is 0.5
It is preferably about 5 μm. Therefore, in the case of a two-layer structure in which a normal tensile insulating film is formed on a tensile insulating film containing a nitrided / oxide of Si, the two layers are combined.
It must be about 0.5 to 5 μm thick. In addition, since the above-mentioned ultra-thin base coat and a tensile insulating coat containing a nitride and oxide of Si formed thereon and a normal tensile insulating coat are of the same quality, their adhesion is extremely high, Therefore, as a result, it is possible to form a tensile insulating coating having much better adhesion on the surface of the steel sheet as compared with the conventional method, and thus to obtain a unidirectional silicon steel sheet having extremely low iron loss with good productivity and You can get it at low cost.

[0074]

EXAMPLES Example 1 C: 0.069 wt%, Si: 3.40 wt%, Mn: 0.073 wt%, Se:
0.020 wt%, Sb: 0.025 wt%, Al: 0.020 wt%, N: 0.
A continuously cast slab of silicon steel containing 083 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1350 ° C. for 5 hours and then hot-rolled to a thickness of 2.2 mm. Hot rolled sheet. Then, after performing uniform annealing at 950 ° C, 1000 ° C
Was subjected to two times of cold rolling with intermediate annealing being carried out to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Then, after decarburization and primary recrystallization annealing in 840 ° C wet H ₂ , CaO (20%), Al ₂ O ₃ (70
%), SiO ₂ (10%), and then applied with a slurry, followed by annealing at 850 ° C for 15 hours, and then 850 ° C to 10 ° C / h.
Temperature increased to 1180 ° C at high speed and strongly integrated in Goss direction 2
After the next recrystallized grains to develop and subjected to purification treatment in dry of H ₂ 1220 ° C..

After removing the oxide film on the surface of the silicon steel sheet thus obtained, a smoothing treatment by chemical polishing was performed.
A pickling treatment with% HCl was performed. Then, the silicon steel sheet is diluted with a coating solution for tension insulating coating mainly composed of magnesium phosphate and colloidal silica: 250 cc with 1500 cc of distilled water, and further, SiCl ₄ : 20 cc, FeC
l ₃ : 10 g, Al (NO ₃ ) ₃ : After immersing in a treatment liquid (80 ° C.) to which 5 g was added for 20 seconds, 950 ° C. for 7 minutes, N ₂ (50%) + H ₂ (5
(0%) Treated in a mixed gas to form an ultra-thin undercoat with a thickness of 0.4 μm. After that, a coating solution containing 30 cc of SiCl ₄ added to a coating solution (500 cc) for tensile insulation coating mainly composed of magnesium phosphate and colloidal silica was applied to the surface of the steel sheet, and then baked at 800 ° C. A tension insulating film (about 2 μm thick) in which 0.1% by weight of Si nitride / oxide was finely dispersed was formed.

The results obtained by examining the magnetic properties, adhesion and corrosion resistance of the product thus obtained are shown below. When the smoothing process is performed Adhesion Diameter: It was good without peeling even when bent at 180 ° on a round bar of 15 mm. Corrosion resistance A salt spray test was conducted in 5% NaCl (45 ° C) for 30 days to examine the state of rust on the surface of the silicon steel sheet. When pickling treatment is applied Adhesion Diameter: It was good without peeling even when bent at 180 ° on a round bar of 15 mm. Corrosion resistance A salt spray test was conducted in 5% NaCl (45 ° C) for 30 days to examine the state of rust on the surface of the silicon steel sheet.

Thereafter, the magnetic properties after the above-mentioned product sheet was subjected to strain relief annealing at 800 ° C. for 3 hours were also examined. As shown below, no deterioration of the properties was observed in any case. .

Example 2 C: 0.073 wt%, Si: 3.38 wt%, Mn: 0.070 wt%, Se:
0.020 wt%, Sb: 0.023 wt%, Al: 0.019 wt%, N: 0.
A continuously cast slab of silicon steel containing 075 wt% and Mo: 0.013 wt%, with the balance being substantially Fe, was heated at 1360 ° C. for 4 hours and then hot-rolled to a thickness of 2.0%. mm hot rolled sheet. Then, after performing uniform annealing at 950 ° C, 1000
Cold rolling was performed twice with intermediate annealing at a temperature of ° C to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Then, on the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd resin as a main component is subjected to gravure offset printing so that the non-applied portion has a width of approximately 200 μm in a direction substantially perpendicular to the rolling direction, and a distance between the rolling directions of 4 mm.
And then baked at 200 ° C. for about 20 seconds. At this time, the resist thickness was 2 μm.
The steel plate coated with the etching resist in this way,
By performing electrolytic etching, a linear groove having a width of 200 μm and a depth of 20 μm was formed, and then immersed in an organic solvent to remove the resist. At this time, the electrolytic etching was performed in a NaCl electrolyte at a current density of 10 A / dm ² and a processing time of 20 A / dm ² .
The test was performed under the condition of seconds.

Then, after decarburization and primary recrystallization annealing in 850 ° C. wet H ₂ , MgO (5%), CaO (25%), Al ₂
Slurry coating of an annealing separating agent having the composition of O ₃ (50%), CaSiO ₃ (10%), SiO ₂ (10%), and then annealing at 850 ° C. for 15 hours, 850 ° C. to 12 ° C./h After the temperature was raised to 1150 ° C at a speed of 2 to develop the secondary recrystallized grains strongly integrated in the Goss orientation,
Purification was performed in dry H ₂ at ° C. After removing the oxide film on the surface of the silicon steel sheet thus obtained, the surface of the unidirectional silicon steel sheet was smoothed by chemical polishing.

Next, a silicon steel sheet was diluted with 1500 cc of distilled water of 250 cc of a coating solution for a tension insulating film containing magnesium phosphate and colloidal silica as main components, and further, 15 cc of SiCl ₄ , _{4: 5g, H 3 BO 3} :
After being immersed in a treatment solution (80 ° C) containing 10 g for 20 seconds, it is treated at 900 ° C for 10 minutes in a mixed gas of N ₂ (93%) and H ₂ (7%) to obtain a 0.3 μm thick electrode. A thin undercoat was applied. After that, a coating solution (250c) for tensile insulation coating consisting mainly of magnesium phosphate and colloidal silica
c) A treatment liquid containing 12 cc of SiCl ₄ is applied and baked at 800 ° C to form a tension insulating coating (about 1 µm thick) in which 0.05 wt% of Si nitride / oxide is finely dispersed in the coating. Done.
Then, a tensile insulating coating (about 1 μm thick) containing magnesium phosphate and colloidal silica as main components was further formed thereon in a conventional manner.

The results obtained by examining the magnetic properties, adhesion and corrosion resistance of the product thus obtained are shown below. Adhesion Diameter: good even with 180 ° bending on a 10 mm round bar without delamination. Corrosion resistance A salt spray test was conducted in 5% NaCl (45 ° C) for 30 days to examine the state of rust on the surface of the silicon steel sheet.

Thereafter, the magnetic properties of the above product sheet after the strain relief annealing at 800 ° C. for 3 hours were also investigated. No deterioration in magnetic properties due to strain relief annealing was observed.

Further, a steel sheet which had not been chemically polished and which had been subjected to an acid washing treatment was used in the same manner as described above, and 250 cc of a coating solution for a tension insulating film mainly composed of magnesium phosphate and colloidal silica was added to 1500 cc of distilled water. And then immersed in a treatment solution (80 ° C.) in which 20 cc of SiCl ₄ , 15 g of AlPO ₄ , and 10 g of H ₃ BO ₃ are added in this diluted solution for 20 seconds, and then 900 ° C.
For 10 minutes in N ₂ (93%) + H ₂ (7%) mixed gas, thickness:
Apply an ultra-thin undercoat of 0.2 μm, and then apply
12 SiCl ₄ in a coating solution (250 cc) for tensile insulation coating mainly composed of magnesium phosphate and colloidal silica
Applying the treatment solution with cc added and baking at 800 ° C to form a tensile insulating film (about 1 µm thick) in which 0.01 wt% Si nitride / oxide is finely dispersed in the film, and then further Then, a tension insulating film (about 1 μm thick) containing magnesium phosphate and colloidal silica as main components was formed thereon in accordance with a conventional method. The magnetic properties, adhesion and corrosion resistance of the product thus obtained were as follows. Adhesion Diameter: It was good without peeling even when bent at 180 ° on a round bar of 15 mm. Corrosion resistance A salt spray test was conducted in 5% NaCl (45 ° C) for 30 days to examine the state of rust on the surface of the silicon steel sheet.

With respect to this product plate, the magnetic properties after strain relief annealing at 800 ° C. for 3 hours were also investigated. No deterioration in magnetic properties due to strain relief annealing was observed.

Example 3 C: 0.044 wt%, Si: 3.46 wt%, Mn: 0.070 wt%, Se:
A continuous cast steel slab containing 0.021 wt%, Sb: 0.025 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1340 ° C for 4 hours and then hot-rolled. And a hot-rolled sheet having a thickness of 2.4 mm. Then, after cold annealing at 900 ° C, cold rolling is performed twice with intermediate annealing at 950 ° C.
The final cold-rolled sheet was 0.23 mm thick. Then, on the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd-based resin as a main component is subjected to gravure offset printing so that the non-applied portion has a width of approximately 200 μm in a direction substantially perpendicular to the rolling direction, and a distance between the rolling directions of 4 mm. After applying so that it remains linear in
Bake at ℃ for about 20 seconds. The resist thickness at this time is 2 μm
Met. The steel plate coated with the etching resist in this manner is subjected to electrolytic etching to obtain a width: 200
A linear groove having a thickness of 20 .mu.m and a depth of 20 .mu.m was formed, and then immersed in an organic solvent to remove the resist. The electrolytic etching at this time was performed in a NaCl electrolytic solution under the conditions of a current density of 10 A / dm ² and a processing time of 20 seconds.

Then, after decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., MgO (25%), Al ₂ O ₃ (70%),
Slurry with CaSiO ₃ (5%) annealing separator, then
After the secondary recrystallized grains strongly integrated in the Goss orientation were developed by holding annealing at 0 ° C. for 50 hours, purification treatment was performed in dry H ₂ at 1200 ° C. After removing the oxide film on the surface of the silicon steel sheet thus obtained, the surface of the unidirectional silicon steel sheet was smoothed by chemical polishing.

After that, the silicon steel sheet was diluted with 1500 cc of distilled water of 250 cc of a coating solution for a tension insulating film mainly composed of aluminum phosphate and colloidal silica, and 50 cc of SiCl ₄ was further added to the diluted solution. Treatment solution added (80
C) for 20 seconds, then 950 ° C for 10 minutes, N ₂ (50%) +
The substrate was treated in a mixed gas of H ₂ (50%) to form an extremely thin undercoat having a thickness of 0.6 μm. Then, a coating solution containing 10 cc of SiCl ₄ added to a coating solution (250 cc) for a tensile insulating coating mainly composed of aluminum phosphate and colloidal silica was applied to the surface of the steel sheet, and baked at 800 ° C. wt
% Insulating film with finely dispersed Si nitride / oxide
(About 1 μm thick).

The results obtained by examining the magnetic properties, adhesion and corrosion resistance of the product thus obtained are shown below. Adhesion Diameter: It was good without peeling even when bent at 180 ° on a round bar of 15 mm. Corrosion resistance A salt spray test was conducted in 5% NaCl (45 ° C) for 30 days to examine the state of rust on the surface of the silicon steel sheet.

In addition, an ultra-thin undercoating in which Si nitride / oxide is finely dispersed is formed on a steel plate which has not been chemically polished and is still pickled as described above.・
The magnetic properties, adhesion, and corrosion resistance of the product obtained by applying the tension insulating coating solution in which the oxide was finely dispersed were as follows. Adhesion Diameter: good even with 180 ° bending on a 10 mm round bar without delamination. Corrosion resistance A salt spray test was conducted in 5% NaCl (45 ° C) for 30 days to examine the state of rust on the surface of the silicon steel sheet.

Further, when the magnetic properties of these product sheets after the strain relief annealing at 800 ° C. for 3 hours were examined, no deterioration of the properties was observed in any case as shown below.

[0091]

As described above, according to the present invention, it is possible to obtain an ultra-low iron loss unidirectional silicon steel sheet having extremely excellent iron loss as compared with the conventional material at an extremely low cost and with high productivity. it can.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of a SiCl ₄ solution in a coating solution for a tensile insulating film and the iron loss of a grain-oriented silicon steel sheet for each processing step.

FIG. 2 (a) shows a conventional unidirectional silicon steel sheet in which the surface of a finish-annealed unidirectional silicon steel sheet is simply coated with a tension insulating coating mainly composed of phosphate and colloidal silica; )
Is to add TiN or CrN on the surface of
This is a conventional unidirectional silicon steel sheet in which an ultra-thin ceramic film such as that described above is formed, and a tensile insulating film is further formed on the surface thereof.

FIG. 3 (a) shows a trace of F on the surface of a grain-oriented silicon steel sheet.
An ultra-thin undercoating with finely dispersed nitrides and oxides of e, Si, Al and B etc. is formed, and then overlaid on it, tension insulation is achieved by finely dispersing Si nitrides and oxides in the coating. The conventional unidirectional silicon steel sheet coated with a coating, (b) is a method of nitriding a small amount of Fe, Si, Al and B on the surface of the unidirectional silicon steel sheet.
After forming an ultra-thin undercoat with oxides dispersed finely, a tensile insulating coating with Si nitride / oxides dispersed finely in the coating is formed on top of this, and a normal insulating coating 1 is a conventional unidirectional silicon steel sheet coated with a tensile insulating film.

Claims (10)

[Claims] Claims 1. A finish-annealed unidirectional silicon steel sheet having a sheet thickness of 0.05 to 0.5 mm, and a base film containing phosphate, colloidal silica, and Fe, Si, Al and An ultra-thin film in which one or two or more nitrides / oxides selected from B is finely dispersed is provided and superimposed thereon, and the nitride / oxide of 0.01 to 10 wt% of Si is contained in the film. An ultra-low iron loss unidirectional silicon steel sheet comprising a tension insulating coating mainly composed of phosphate and colloidal silica in which fine particles are dispersed finely. 2. A linear concave region having a thickness of 0.05 to 0.5 mm, a width of 50 to 500 μm, and a depth of 0.1 to 50 μm is provided at intervals of 2 to 10 mm in a direction intersecting with the rolling direction. On the surface of the finish-annealed unidirectional silicon steel sheet, as a base coat, a coating containing phosphate and colloidal silica as main components Fe, Si,
An ultra-thin film in which one or two or more types of nitrides and oxides selected from Al and B are finely dispersed is provided, and is superposed thereon to form a nitride film of 0.01 to 10 wt% of Si. An ultra-low iron loss unidirectional silicon steel sheet having a tension insulating coating mainly composed of phosphate and colloidal silica in which oxides are finely dispersed. 3. A finish-annealed unidirectional silicon steel sheet having a sheet thickness of 0.05 to 0.5 mm, and a base coat containing phosphate, colloidal silica as a main component and Fe, Si, Al and An ultra-thin film in which one or two or more nitrides / oxides selected from B is finely dispersed is provided and superimposed thereon, and the nitride / oxide of 0.01 to 10 wt% of Si is contained in the film. A finely dispersed phosphate insulating film mainly composed of phosphate and colloidal silica, and further a normal phosphate and colloidal silica not containing nitride and oxide as described above. An ultra-low iron loss unidirectional silicon steel sheet having a tension insulating coating. 4. A linear concave region having a thickness of 0.05 to 0.5 mm, a width of 50 to 500 μm, and a depth of 0.1 to 50 μm is provided at intervals of 2 to 10 mm in a direction intersecting the rolling direction. On the surface of the finish-annealed unidirectional silicon steel sheet, as a base coat, a coating containing phosphate and colloidal silica as main components Fe, Si,
An ultra-thin film in which one or two or more types of nitrides and oxides selected from Al and B are finely dispersed is provided, and is superposed thereon to form a nitride film of 0.01 to 10 wt% of Si. A tension insulating coating mainly composed of phosphate and colloidal silica in which oxides are finely dispersed, and a normal phosphate and colloidal silica not containing nitride and oxide as described above as main components. An ultra-low iron loss unidirectional silicon steel sheet having a tension insulating film. 5. The ultra-low iron loss unidirectional silicon steel sheet according to claim 1, wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface subjected to a smoothing treatment. 6. The ultra-low iron loss unidirectional steel sheet according to claim 1, 2, 3 or 4, wherein the surface of the finish-annealed unidirectional silicon steel sheet is a surface which has not been subjected to a smoothing treatment and is as-picked. Silicon steel sheet. 7. A coating solution for a tension insulating coating mainly composed of phosphate and colloidal silica is diluted with water on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment solution in which a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B is added to the diluent, a small amount of Fe, Si , Al and B, and then a short-time heat treatment in a non-oxidizing atmosphere is applied to the surface of the steel sheet so that Fe is contained in a coating component. An ultra-thin undercoating is formed by finely dispersing one or more nitrides and oxides selected from Si, Al, and B, and then phosphate and colloidal silica are mainly applied. Of Si chloride added to the coating liquid for tensile insulation coating By applying and baking a solution, a tensile insulating film is formed by finely dispersing 0.01 to 10 wt% of Si nitride / oxide in the film. Production method. 8. A linear concave region having a thickness of 0.05 to 0.5 mm, a width of 50 to 500 μm, and a depth of 0.1 to 50 μm is provided at an interval of 2 to 10 mm in a direction intersecting with the rolling direction. On the surface of the finish-annealed unidirectional silicon steel sheet, a coating solution for a tension insulating film mainly composed of phosphate and colloidal silica is diluted with water, and the diluted solution contains Fe, Si, Al and B. By applying and drying a treatment liquid containing a small amount of an inorganic compound containing one or more selected from the group, one or two selected from trace amounts of Fe, Si, Al and B on the steel sheet surface. After attaching an inorganic compound containing at least one kind, a short-time heat treatment is performed in a non-oxidizing atmosphere, and one type selected from Fe, Si, Al and B in a film component on the surface of the steel sheet. Alternatively, an ultra-thin undercoating in which two or more types of nitrides / oxides are finely dispersed is formed, and By coating and baking a treatment solution containing Si chloride added to a coating solution for tensile insulating coatings mainly composed of phosphate and colloidal silica, 0.01 to 10 wt% of Si
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising forming a tension insulating film in which an oxide is finely dispersed. 9. A coating solution for a tension insulating coating mainly composed of phosphate and colloidal silica is diluted with water on the surface of a finish-annealed unidirectional silicon steel sheet having a thickness of 0.05 to 0.5 mm, and By applying and drying a treatment solution in which a small amount of an inorganic compound containing one or more selected from Fe, Si, Al and B is added to the diluent, a small amount of Fe, Si , Al and B, and then a short-time heat treatment in a non-oxidizing atmosphere is applied to the surface of the steel sheet so that Fe is contained in a coating component. An ultra-thin undercoating is formed by finely dispersing one or more nitrides and oxides selected from Si, Al, and B, and then phosphate and colloidal silica are mainly applied. Of Si chloride added to the coating liquid for tensile insulation coating The solution is applied and baked to form a tension insulating film in which 0.01 to 10 wt% of Si nitride / oxide is finely dispersed in the film, and further, phosphate and colloidal silica are formed thereon in a conventional manner. A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising forming a normal tensile insulating coating mainly composed of iron. 10. A linear concave area having a thickness of 0.05 to 0.5 mm, a width of 50 to 500 μm, and a depth of 0.1 to 50 μm is provided at an interval of 2 to 10 mm in a direction intersecting with the rolling direction. On the surface of the finish-annealed unidirectional silicon steel sheet, a coating solution for a tensile insulating film mainly composed of phosphate and colloidal silica is diluted with water, and the diluted solution contains Fe, Si, Al and B. By applying and drying a treatment liquid containing a small amount of an inorganic compound containing one or more selected from the group, one or two or more selected from among a small amount of Fe, Si, Al and B on the steel sheet surface. After attaching an inorganic compound containing at least one species, a short-time heat treatment is performed in a non-oxidizing atmosphere, and the surface of the steel sheet is coated with one kind selected from Fe, Si, Al and B in a coating component. Alternatively, an ultra-thin undercoating in which two or more types of nitrides / oxides are finely dispersed is formed, and then, By coating and baking a treatment solution containing Si chloride in a coating solution for tensile insulating coatings mainly composed of phosphate and colloidal silica, 0.01 to 10 wt% of Si is nitrided in the coating.
Forming a tension insulating coating in which oxides are finely dispersed, and further forming a normal tensile insulating coating containing phosphate and colloidal silica as main components in accordance with a conventional method; A method for producing a low iron loss unidirectional silicon steel sheet.