Annealing release agent composition for grain-oriented electrical steel sheets and method for manufacturing grain-oriented electrical steel sheets

Abstract

The present invention provides an annealing separator composition for grain-oriented electrical steel sheet, which has excellent adhesion and film tension and can improve the iron loss of the material, and a method for producing grain-oriented electrical steel sheet. An annealing separator composition for grain-oriented electrical steel sheet according to one embodiment of the present invention contains, based on 100% by weight of total solids, 25 to 80% by weight of a boron compound, and the remainder being one or more of magnesium oxide and magnesium hydroxide.

Description

[Technical Field]

[0001] One embodiment of the present invention is directional electromagnetic Annealing release agent composition for steel plates and orientation electromagnetic Regarding the manufacturing method of steel sheets, more specifically, directions including boron compounds electromagnetic Annealing release agent composition for steel plates and orientation electromagnetic Regarding the manufacturing method of steel plates. [Background technology]

[0002] Generally, direction electromagnetic Steel sheet is a steel sheet containing Si components, with a crystal grain orientation of {110}. <001> It has a texture aligned in the direction and possesses extremely excellent magnetic properties in the rolling direction. electromagnetic It refers to steel plates. Generally known directions electromagnetic In the case of steel sheets, an insulating film is formed on a forsterite (Mg2SiO4)-based film, and by utilizing the difference in thermal expansion coefficients of such insulating films to apply tensile stress to the steel sheet, iron loss is improved and noise caused by magnetic deformation is reduced. However, the high-grade directional coatings that have been required recently electromagnetic There are limits to satisfying the required performance level with steel plates.

[0003] Traditionally, direction electromagnetic In the steel sheet manufacturing process, a method has been proposed to improve surface properties by using TiO2 powder instead of MgO in the step of applying an anti-fusion agent mainly composed of MgO in order to improve the forsterite coating properties. Furthermore, in order to improve the film tension compared to conventional forsterite, kaolinite (Al4Si4O) is used on the surface of the decarburized annealed plate. 10A method has been proposed in which (OH)8) is applied as an annealing separating agent and finish annealing is performed to form a composite film composed of alumina and silica on the surface of the steel sheet. However, this method is a composite film formation technique that decomposes kaolinite and consists of a double-layered composite film composed of alumina on top and silica on the bottom. This method has problems in that it is difficult to control the secondary recrystallization annealing process, making it difficult to form a uniform quality, and the adhesion is poor due to the silica film formed on the bottom.

[0004] Also, direction electromagnetic As a method to improve iron loss in steel sheets, a method is known in which alumina powder or a mixture of colloidal silica and MgCl2 is applied as an anti-fusion agent to remove the forsterite film. However, by removing the forsterite film, such a method is necessary. electromagnetic There is a problem in that the iron loss of the steel sheet actually worsens, and it becomes difficult to form an insulating film in subsequent processes. [Overview of the project] [Problems that the invention aims to solve]

[0005] The objective of the present invention is directionality electromagnetic Annealing release agent composition for steel plates and orientation electromagnetic The objective is to provide a method for manufacturing steel sheets. Specifically, a direction that can improve adhesion and film tension and reduce iron loss in the material. electromagnetic Annealing release agent composition for steel plates and orientation electromagnetic The objective is to provide a method for manufacturing steel plates. [Means for solving the problem]

[0006] Directional Directional Direction According to One Embodiment of the Invention electromagnetic The annealing separation agent composition for steel plates is characterized by containing 25 to 80% by weight of a boron compound, and the remainder being one or more of magnesium oxide and magnesium hydroxide, based on 100% by weight of total solids.

[0007] Boron compounds include BBr3, BCl3, BF, BF3, BI3, BN, B(NO3)3, B(OH)3, BP, BPO4, B2F4, B2Cl4, B2H6, BH3NH3, B2O, B2O3, B2S3, B4C, B6O, B5H9, and B5H 11 B6H 10 B6H 12 It may contain one or more of the following: LiBH4, H3BO3, Na2B4O7, H2B4O7, B2O3, B2O, B2C, MgB2, H[B(OH)4], H[BF(OH)3], H[BF2(OH)2], H[BF3(OH)], and H[BF4].

[0008] Directional Directional Direction According to One Embodiment of the Invention electromagnetic The annealing separation agent composition for steel plates may further contain 0.1 to 20% by weight of metal hydroxide.

[0009] Metal hydroxides may include one or more of the following: Ni(OH)2, Co(OH)2, Cu(OH)2, Sr(OH)2, Ba(OH)2, Pd(OH)2, In(OH)3, Bi(OH)3, and Sn(OH).

[0010] Directional Directional Direction According to One Embodiment of the Invention electromagnetic The annealing separation agent composition for steel plates may further contain 0.5 to 10% by weight of ceramic powder.

[0011] The ceramic powder may contain one or more of the following: MnO, Al2O3, SiO2, TiO2, and ZrO.

[0012] Directional Directional Direction According to One Embodiment of the Invention electromagnetic The annealing separation agent composition for steel plates may further contain 1 to 10% by weight of one or more of Sb2(SO4)3, SrSO4, and BaSO4.

[0013] Directional Directional Direction According to One Embodiment of the Invention electromagnetic Steel plates have a directional electromagnetic Steel sheet substrate and orientation electromagneticIt is located on one or both sides of the steel plate substrate and includes a film containing boron and forsterite. The film may contain boron aggregates, and the average particle size of the boron aggregates may be 1 to 500 nm.

[0014] The boron aggregates can be contained in an amount of 1 to 45 area% with respect to the total area of the film.

[0015] The film can contain B in an amount of 1 to 40% by weight, Mg in an amount of 10 to 70% by weight, Si in an amount of 3 to 70% by weight, O in an amount of 10 to 90% by weight, and the balance as Fe.

[0016] Directivity according to an embodiment of the present invention electromagnetic The steel plate can further include a ceramic layer located on the film.

[0017] The ceramic layer can contain ceramic powder and metal phosphate.

[0018] The ceramic powder can contain one or more selected from Al2O3, SiO2, TiO2, ZrO2, Al2O3·TiO2, Y2O3, 9Al2O3·2B2O3, BN, CrN, BaTiO3, SiC, and TiC.

[0019] Directivity according to an embodiment of the present invention electromagnetic The method for manufacturing a steel plate includes the step of preparing a steel slab 、 The step of hot-rolling the steel slab to produce a hot-rolled sheet 、 The step of cold-rolling the hot-rolled sheet to produce a cold-rolled sheet 、 The step of performing primary recrystallization annealing on the cold-rolled sheet 、 The step of applying an annealing separating agent on the surface of the steel sheet subjected to primary recrystallization annealing 、 And the step of performing secondary recrystallization annealing on the steel sheet coated with the annealing separating agent 、 And includes, wherein the annealing separating agent contains 25 to 80% by weight of a boron compound and one or more of magnesium oxide and magnesium hydroxide in the balance based on 100% by weight of the total solid content.

[0020] The process may further include the step of forming a ceramic layer on a film containing boron and forsterite after the step of secondary recrystallization annealing. The film containing boron and forsterite may contain 1 to 40% by weight of B, 10 to 70% by weight of Mg, 3 to 70% by weight of Si, 10 to 90% by weight of O, and the remainder being Fe.

[0021] The step of forming the ceramic layer may also be a step of forming the ceramic layer by spraying ceramic powder onto the film. The step of forming the ceramic layer may also involve applying a ceramic layer-forming composition containing ceramic powder and metal phosphate onto the film to form the ceramic layer. The ceramic powder used in the step of forming the ceramic layer may include one or more selected from Al2O3, SiO2, TiO2, ZrO2, Al2O3·TiO2, Y2O3, 9Al2O3·2B2O3, BN, CrN, BaTiO3, SiC, and TiC.

[0022] The step of primary recrystallization annealing of the cold-rolled sheet may include the step of simultaneously decarburizing and nitriding the cold-rolled sheet, or may include the step of nitriding after decarburizing annealing. [Effects of the Invention]

[0023] According to one embodiment of the present invention, a directional coating is available that is excellent in iron loss and magnetic flux density, and has excellent adhesion and insulation properties. electromagnetic We can provide steel plates and methods for manufacturing the same. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic side cross-sectional view of a grain-oriented electrical steel sheet according to one embodiment of the present invention. [Figure 2] This is a scanning electron microscope (SEM) image of the coating on the grain-oriented electrical steel sheet manufactured in Example 9. [Figure 3] This is a scanning electron microscope (SEM) image of the coating on the grain-oriented electrical steel sheet manufactured in Comparative Example 2. [Figure 4] This shows the results of EPMA (Electron Probe Micro-Analyzer) analysis of the B-element coating on the grain-oriented electrical steel sheet manufactured in Example 3. [Figure 5] This shows the results of EPMA (Electron Probe Micro-Analyzer) analysis of the B-element coating on the grain-oriented electrical steel sheet manufactured in Example 6. [Figure 6] This shows the results of EPMA (Electron Probe Micro-Analyzer) analysis of the coating on the grain-oriented electrical steel sheet manufactured in Comparative Example 3. [Modes for carrying out the invention]

[0025] The terms first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are used solely to distinguish one part, component, region, layer, or section from other parts, components, regions, layers, or sections. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section, without departing from the scope of the invention.

[0026] The technical terms used herein are for the sole purpose of referring to specific embodiments and are not intended to limit the invention. The singular form as used herein also includes the plural form unless the wording explicitly indicates the opposite. The meaning of “includes” as used herein is to embody a particular characteristic, domain, integer, step, operation, element and / or component, and does not exclude the presence or addition of other characteristics, domains, integers, steps, operations, elements and / or components.

[0027] When it is stated that one part is "on top of" or "above" another part, it may be exactly on top of or above the other part, or it may have the other part between them. In contrast, when it is stated that one part is "directly on top of" another part, there is no other part between them.

[0028] Furthermore, in this invention, 1 ppm means 0.0001%. In one embodiment of the present invention, the meaning of further including an additional component means that the remainder is replaced by the additional amount of the additional component. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries are to be interpreted as having the meaning consistent with the relevant technical literature and the present disclosures, and are not to be interpreted in an ideal or extreme sense unless otherwise defined.

[0029] The following describes embodiments of the present invention in detail so that those with ordinary skill in the art to which the present invention pertains can easily implement it. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein.

[0030] Directional Directional Direction According to One Embodiment of the Invention electromagnetic The annealing separation agent composition for steel plates contains 25-80% by weight of a boron compound, with the remainder being one or more of magnesium oxide and magnesium hydroxide, based on solid content. Here, "based on solid content" means that the solid content, excluding volatile components such as solvents, is set to 100% by weight.

[0031] The following describes in detail, component by component, an annealing separation agent composition according to one embodiment of the present invention. An annealing separating agent composition according to one embodiment of the present invention has directionality electromagnetic The coating 20, which contains boron and forsterite, is applied to the steel plate substrate 10. Boron has a low coefficient of thermal expansion (5 × 10 -6 At [temperature]°C, iron loss can be easily improved by applying film tension. In addition, because boron has a relatively low modulus of elasticity, it has excellent thermal shock resistance.

[0032] The existing primary forsterite (Mg2SiO4) coating is formed by a chemical reaction between the internal oxide layer (SiO2) present on the steel sheet surface and magnesium oxide (MgO) in the annealing separation agent during secondary recrystallization annealing. While conventional forsterite coatings excel at preventing sheet sticking due to contact between coils during the secondary recrystallization annealing process, they have limitations in terms of coating tension-granting ability and insulation properties.

[0033] In one embodiment of the present invention, by adding a boron compound to magnesium oxide or magnesium hydroxide, the film tension-imparting ability and insulating properties can be dramatically improved. However, when a boron compound is used alone as an annealing separating agent, there is a problem that the difference in thermal expansion coefficients during the secondary recrystallization annealing process is severe, causing the film to peel off. Furthermore, when the boron component is used as an annealing separating agent, it has a high specific gravity and tends to sink without dispersing in the solvent. electromagnetic It can be difficult to apply the material uniformly to the surface of a steel plate. In one embodiment of the present invention, boron is used not alone, but in mixture with magnesium oxide or magnesium hydroxide.

[0034] Kaolinite (Al4Si4O 10 When (OH)8) is included as an annealing separating agent, it is difficult to control the secondary recrystallization annealing process, making it difficult to form uniform quality, and there is a problem of poor adhesion due to the silica film formed at the bottom by the decomposition of kaolinite. In one embodiment of the present invention, the annealing separation agent composition contains 25 to 80% by weight of a boron compound based on solid content. If the boron compound content is low, forsterite film formation may be insufficient, resulting in poor adhesion. Furthermore, the ability to impart film tension and improve insulation properties may be insufficient. If the boron compound content is too high, problems may arise in uniformly applying the annealing separation agent. Therefore, the boron compound can be included within the aforementioned content range. More specifically, the boron compound can be included in 30 to 70% by weight.

[0035] Boron compounds can exist in various forms. Specifically, they may be in the form of chlorides, oxides, nitrates, sulfides, etc. More specifically, they may be BBr3, BCl3, BF, BF3, BI3, BN, B(NO3)3, B(OH)3, BP, BPO4, B2F4, B2Cl4, B2H6, BH3NH3, B2O, B2O3, B2S3, B4C, B6O, B5H9, B5H 11 , B6H 10 , B6H 12 , LiBH4, H3BO3, Na2B4O7, H2B4O7, B2O3, B2O, B2C, MgB2, H[B(OH)4], H[BF(OH)3], H[BF2(OH)2], H[BF3(OH)], and H[BF4], and can contain one or more selected from them. When containing two or more boron compounds, the total amount thereof is 25 to 80% by weight.

[0036] In one embodiment of the present invention, the annealing release agent composition may contain 5 to 600 parts by weight of a boron compound with respect to 100 parts by weight of one or more of magnesium oxide and magnesium hydroxide based on the solid content mass. Specifically, the boron compound can contain 10 to 500 parts by weight, and more specifically, 50 to 300 parts by weight. If the content of boron compared to magnesium oxide or magnesium hydroxide is too low, the formation of the forsterite film may not be sufficient and the adhesion may be poor. Also, the ability to impart film tension and the ability to impart insulation properties may not be sufficient. If it is too much, the function of the annealing release agent may deteriorate and the phenomenon of sticking between plates may occur during the high-temperature annealing process.

[0037] Metal hydroxides play a role in changing the surface properties of boron compounds from hydrophobic to hydrophilic through chemical reactions with the surface. Therefore, they dramatically improve the dispersibility of boron compounds and help form a uniform forsterite film. Furthermore, the melting point of the metal hydroxide is lowered, resulting in a lower film formation temperature during the secondary recrystallization annealing process, thus ensuring excellent surface properties. Additionally, forsterite films formed at low temperatures suppress the decomposition of AlN-based inhibitors, which critically affect secondary recrystallization, thus ensuring superior magnetic quality.

[0038] In one embodiment of the present invention, the annealing separation agent composition may further contain 0.1 to 20% by weight of metal hydroxide. If the amount of metal hydroxide is too small, problems may arise in fully exhibiting the effects described above. If the amount of metal hydroxide is too large, problems may arise in that the forsterite formation behavior becomes non-uniform because the metal component diffuses internally and forms a film. If the annealing separation agent further contains additional components, these can be substituted for the remainder of magnesium oxide and magnesium hydroxide. In this context, metal hydroxide refers to metal hydroxides excluding magnesium hydroxide, as mentioned above. Specifically, metal hydroxides may include one or more selected from Cr(OH)3, Ni(OH)2, Co(OH)2, Cu(OH)2, Sr(OH)2, Ba(OH)2, Pd(OH)2, In(OH)3, Bi(OH)3, and Sn(OH). Magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)2) play a role in supplying Mg to the film. In one embodiment of the present invention, the annealing separating agent composition is directional electromagnetic To facilitate easy application to the surface of a steel plate substrate, it can exist in slurry form. When water is included as the solvent in the slurry, magnesium oxide readily dissolves in water and can also exist in the form of magnesium hydroxide. Therefore, in one embodiment of the present invention, magnesium oxide and magnesium hydroxide are treated as a single component.

[0039] An annealing separation agent composition according to one embodiment of the present invention may further contain 0.5 to 10% by weight of ceramic powder. The ceramic powder may include one or more selected from MnO, Al2O3, SiO2, TiO2, and ZrO. When an appropriate amount of ceramic powder is further included, the insulating properties of the formed film 20 can be further improved.

[0040] An annealing separation agent composition according to one embodiment of the present invention may further contain 1 to 10% by weight of Sb2(SO4)3, SrSO4, BaSO4, or a combination thereof. By further containing an appropriate amount of Sb2(SO4)3, SrSO4, BaSO4, or a combination thereof, excellent surface gloss and very beautiful directional roughness can be achieved. electromagnetic Steel plates can be manufactured. The annealing separation agent composition may further contain a solvent for uniform dispersion of solids and easy application. The solvent can be water, alcohol, or the like, and may be present in an amount of 300 to 1000 parts by weight per 100 parts by weight of solids. Thus, the annealing separation agent composition may be in slurry form.

[0041] Directional Directional Direction According to One Embodiment of the Invention electromagnetic Steel plate 100 is directional electromagnetic A coating 20 containing boron and forsterite is formed on one or both sides of the steel plate substrate 10. Figure 1 shows the orientation according to one embodiment of the present invention. electromagnetic A schematic side cross-sectional view of a steel plate is shown. Figure 1 shows the directionality. electromagnetic This shows the case where a coating 20 is formed on the upper surface of the steel plate substrate 10. The coating 20 containing boron and forsterite exhibits superior coating tension-imparting ability and insulating properties compared to conventional forsterite coatings. Its melting point is lower, resulting in a lower coating 20 formation temperature during the secondary recrystallization annealing process, thus ensuring good surface properties. Furthermore, the coating 20 formed at a low temperature suppresses the decomposition of AlN-based inhibitors, which have a decisive impact on secondary recrystallization, thus ensuring excellent magnetic quality. As this has been explained previously, a redundant explanation will be omitted.

[0042] The coating 20 may contain 1-40% by weight of B, 10-70% by weight of Mg, 3-70% by weight of Si, 10-90% by weight of O, and the remainder being Fe. The elemental compositions of Mg, Si, and Fe originate from diffusion from the steel sheet and from annealing separation agent components. In the case of O, it may originate from the annealing separation agent components or penetrate during the heat treatment process. Other impurity components such as carbon (C) may also be included. In the case of B, it originates from the annealing separation agent components, and by including B within the above range, the coating 20 improves its ability to impart film tension and its insulating properties.

[0043] In one embodiment of the present invention, the elemental content within the film may vary depending on the measurement location, and the aforementioned elemental range refers to the average elemental content within the film 20. More specifically, it may contain 1.0 to 40.0% by weight of B, 15.0 to 50.0% by weight of Mg, 10.0 to 30.0% by weight of Si, 20.0 to 50.0% by weight of O, and the remainder being Fe.

[0044] Within the film 20, B is composed of BBr3, BCl3, BF, BF3, BI3, BN, B(NO3)3, B(OH)3, BP, BPO4, B2F4, B2Cl4, B2H6, BH3NH3, B2O, B2O3, B2S3, B4C, B6O, B5H9, B5H 11 B6H 10 B6H 12Boron can exist in the form of boron aggregates such as LiBH4, H3BO3, Na2B4O7, H2B4O7, B2O3, B2O, B2C, MgB2, H[B(OH)4], H[BF(OH)3], H[BF2(OH)2], and H[BF3(OH)]. In particular, it can exist in the form of borosilicates, magnesium borate, boaluminosilicates, or composites thereof. When boron aggregates are present in the film 20, the film tension-imparting ability and insulation properties are improved. For appropriate improvement of film tension-imparting ability and insulation properties, the average particle size of the boron aggregates can be 1 to 500 nm. In this case, the average particle size refers to the number-average particle size of boron aggregates observed on the surface of the film 20 using EPMA (Electron Probe X-ray Micro Analyzer) in an area of ​​400 μm × 400 μm or more, which is a non-destructive dissociation method. The particle size refers to the equivalent circular diameter of the boron aggregate. Boron aggregates refer to aggregates of B that have aggregated above the basal level of the coating 20 and have a particle size of 1 nm or larger. More specifically, the average particle size of the boron aggregates may be 3 to 500 nm. More specifically, the average particle size of the boron aggregates may be 10 to 200 nm. Furthermore, the boron aggregates may occupy 1 to 45 area percent of the coating 20. More specifically, they may occupy 2 to 35 area percent.

[0045] The coating 20 may have a thickness of 0.1 to 10 μm. If the coating 20 is too thin, the coating tension-imparting ability may decrease, potentially leading to problems with poor iron loss. If the coating 20 is too thick, the drip rate may decrease, potentially leading to problems with poor transformer characteristics. Therefore, the thickness of the forsterite coating 20 can be adjusted within the aforementioned range. More specifically, the thickness of the forsterite coating 20 can be 0.8 to 6 μm. The boundary between the coating 20 and the steel plate substrate 10 can be divided in the thickness direction of the steel plate into a portion of the coating 20 containing 5% by weight or more of Mg and a portion containing less than 5% by weight of Mg. Even if a ceramic layer 30 is further formed on the coating 20, it can be divided into a portion of the coating 20 containing 5% by weight or more of Mg and a portion of the ceramic layer 30 containing less than 5% by weight of Mg, based on 5% by weight of Mg.

[0046] Directional Directional Direction According to One Embodiment of the Invention electromagnetic The steel plate 100 can have a ceramic layer 30 further formed on the coating 20. Figure 1 shows an example in which a ceramic layer 30 is further formed on the coating 20.

[0047] The thickness of the ceramic layer 30 can be 0.5 to 5 μm. If the thickness of the ceramic layer 30 is too thin, a problem may arise in that the insulating effect of the ceramic layer 30 is reduced. If the thickness of the ceramic layer 30 is too thick, the adhesion of the ceramic layer 30 will be reduced, and delamination may occur. Therefore, the thickness of the ceramic layer 30 can be adjusted within the range described above. More specifically, the thickness of the ceramic layer 30 can be 0.8 to 3.2 μm.

[0048] The ceramic layer 30 may contain ceramic powder. The ceramic powder may be one or more selected from Al2O3, SiO2, TiO2, ZrO2, Al2O3·TiO2, Y2O3, 9Al2O3·2B2O3, BN, CrN, BaTiO3, SiC, and TiC. The particle size of the ceramic powder can be 2 to 900 nm. If the particle size of the ceramic powder is too small, it may be difficult to form the ceramic layer. If the particle size of the ceramic powder is too large, the surface roughness will be rough and surface defects may occur. Therefore, the particle size of the ceramic powder can be adjusted to the range described above. The ceramic powder may be in one or more forms selected from the group including spherical, plate-like, and needle-like shapes.

[0049] The ceramic layer 30 may further contain a metal phosphate. The metal phosphate may include one or more selected from Mg, Ca, Ba, Sr, Zn, Al, and Mn. The presence of a metal phosphate further improves the insulating properties of the ceramic layer 30. The metal phosphate may consist of a compound obtained by the chemical reaction of a metal hydroxide and phosphoric acid (H3PO4). Metal phosphates consist of compounds formed by the chemical reaction of a metal hydroxide and phosphoric acid (H3PO4), and the metal hydroxide may be at least one selected from the group including Ca(OH)2, Al(OH)3, Mg(OH)2, B(OH)3, Co(OH)2, and Cr(OH)3.

[0050] Specifically, the metal atoms of the metal hydroxide may be those that have undergone a substitution reaction with phosphorus in phosphoric acid to form single, double, or triple bonds, and the compound may contain 25% by weight or less of unreacted free phosphoric acid (H3PO4). Metal phosphates are compounds formed by the chemical reaction of metal hydroxides and phosphoric acid (H3PO4), and the weight ratio of metal hydroxide to phosphoric acid may be expressed as 1:100 to 40:100. If the amount of metal hydroxide is too high, the chemical reaction may not be completed, potentially leading to the formation of precipitates. Conversely, if the amount of metal hydroxide is too low, the corrosion resistance may be poor. Therefore, the range can be limited as described above.

[0051] In one embodiment of the present invention, directionality electromagnetic The effects of the annealing separation agent composition and the coating 20 appear independently of the components of the steel plate substrate 10. Additionally, directionality electromagnetic The components of the steel plate base material 10 are as follows: Direction electromagnetic The steel plate substrate 10 contains silicon (Si): 2.8-4.5 wt%, aluminum (Al): 0.020-0.040 wt%, manganese (Mn): 0.01-0.20 wt%, and antimony (Sb), tin (Sn), nickel (Ni), or a combination thereof in 0.01-0.15 wt%, with the remainder being Fe and other unavoidable impurities. Below is the direction electromagnetic The reason for limiting the composition of the steel plate base material 10 will be explained.

[0052] Si:2.8~4.5wt% Silicon (Si) plays a role in increasing the resistivity of steel and reducing iron loss. However, if the Si content is too low, the resistivity of the steel will decrease, the iron loss characteristics will deteriorate, and problems may arise such as the existence of a phase transformation zone during high-temperature annealing and unstable secondary recrystallization. If the Si content is too high, brittleness will increase, and problems may arise such as difficulty in cold rolling. Therefore, the Si content can be adjusted within the aforementioned range. More specifically, Si can be included in an amount of 3.0 to 4.0% by weight.

[0053] Al:0.020~0.040wt% Aluminum (Al) ultimately forms nitrides of the forms AlN, (Al,Si)N, and (Al,Si,Mn)N, and acts as an inhibitory component. If the Al content is too low, a sufficient inhibitory effect cannot be expected. Conversely, if the Al content is too high, the Al-based nitrides will precipitate and grow coarsely, which may result in insufficient inhibitory effect. Therefore, the Al content can be adjusted within the aforementioned range.

[0054] Mn:0.01~0.20wt% Manganese (Mn), like Si, increases resistivity and reduces iron loss. It is an important element for suppressing primary recrystallization grain growth and inducing secondary recrystallization by reacting with nitrogen, which is introduced along with Si during nitriding, to form (Al,Si,Mn)N precipitates. However, if the Mn content is too high, it promotes austenite phase transformation during hot rolling, reducing the size of primary recrystallization grains and making secondary recrystallization unstable. Conversely, if the Mn content is too low, it increases the austenite fraction during hot rolling reheating as an austenite-forming element, leading to a large volume of precipitates. This may result in insufficient refinement of the precipitates and prevention of excessive primary recrystallization grain size due to MnS formation during reprecipitation. Therefore, the Mn content can be adjusted within the aforementioned range.

[0055] Sb, Sn, Ni, or combinations thereof: 0.01-0.15% by weight Antimony (Sb), tin (Sn), and nickel (Ni) are elements that hinder grain movement as grain segregation elements, and therefore are used as grain growth inhibitors {110}. <001> These elements are important for controlling grain size because they promote the formation of oriented gothic crystal grains and allow secondary recrystallization to develop well. If the content of Sb, Sn, or Ni, either individually or in combination, is too low, problems may arise where their effect is reduced. If the content of Sb, Sn, or Ni, either individually or in combination, is too high, grain segregation becomes severe, the brittleness of the steel sheet increases, and sheet fracture may occur during rolling. More specifically, the content can be 0.01-0.05 wt% of Sb, 0.01-0.12 wt% of Sn, and 0.01-0.06 wt% of Ni.

[0056] C: 0.01% by weight or less In the embodiment of the present invention, C is directional electromagnetic Since it is a component that does not significantly contribute to improving the magnetic properties of steel sheets, it is preferable to remove it if possible. However, if it is present above a certain level, it promotes the austenitic transformation of steel during the rolling process, which helps to refine the hot-rolled structure during hot rolling and to help form a uniform microstructure. Therefore, it is desirable for the carbon content in the slab to be 0.03% by weight or more. However, if the carbon content is excessive, coarse carbides are generated, which are difficult to remove during decarburization, so it is preferable for it to be 0.08% by weight or less. Directional electromagnetic During the manufacturing process of steel sheets, carbon is removed through the decarburization annealing process, resulting in the final product. electromagnetic The amount of carbon (C) in the steel plate will be reduced to 0.01% by weight or less.

[0057] N:0.005~0.05wt% Nitrogen (N) is an element that reacts with elements such as Al to refine the crystal grains. When these elements are appropriately distributed, they help to appropriately refine the microstructure after cold rolling, as described above, and ensure an appropriate primary recrystallization grain size. However, if the content is excessive, the primary recrystallization grains are excessively refined, and as a result, the driving force for grain growth during secondary recrystallization by the fine crystal grains becomes larger, potentially leading to the growth of crystal grains in undesirable orientations. Furthermore, if the N content is excessive, it takes a lot of time to remove it during the final annealing process, which is undesirable. Therefore, the upper limit of the nitrogen content in the slab should be 0.005% by weight, and the nitrogen content employed during slab reheating must be 0.001% by weight or more, so it is desirable that the lower limit of the nitrogen content in the slab be 0.001% by weight. electromagnetic During the manufacturing process of steel plates, nitrogen partially penetrates through the immersion annealing process, and the directionality of the final product is determined by the manufacturing process. electromagnetic The steel plate will contain 0.005 to 0.05% by weight of nitrogen.

[0058] Directional Directional Direction According to One Embodiment of the Invention electromagnetic The method for manufacturing steel plates involves the step of preparing a steel slab (S10). 、 Step (S20): Hot-rolling a steel slab to produce a hot-rolled sheet. 、 Hot-rolled sheet is cold-rolled 、 Steps for manufacturing cold-rolled sheets (S30) 、 Step (S40) of performing primary recrystallization annealing on the cold-rolled sheet. 、 Step (S50): Apply an annealing separating agent to the surface of a steel sheet that has undergone primary recrystallization annealing. 、 The process also includes the step (S60) of performing secondary recrystallization annealing on a steel sheet coated with an annealing separating agent. electromagnetic The method for manufacturing steel plates may further include other steps.

[0059] First, in step (S10), the steel slab is prepared. Regarding the composition of the steel slab, the directionality mentioned above applies. electromagnetic Since the composition of the steel plate has been explained in detail, repeated explanations will be omitted. Next, the steel slab can be heated. At this time, the slab can be heated at a temperature of 1,200°C or lower using the low-temperature slab method. Next, in step (S20), the heated steel slab is hot-rolled to produce a hot-rolled sheet. After step (S20O), the produced hot-rolled sheet can be hot-rolled and annealed. Next, in step (S30), the hot-rolled sheet is cold-rolled to produce a cold-rolled sheet. Step (S30) may involve one cold-rolling step or two or more cold-rolling steps, including intermediate annealing.

[0060] Next, in step (S40), the cold-rolled sheet is subjected to primary recrystallization annealing. At this time, the step of primary recrystallization annealing of the cold-rolled sheet may include a step of simultaneously decarburizing annealing and nitriding annealing of the cold-rolled sheet, or it may include a step of nitriding annealing after decarburizing annealing. Next, in step (S50), an annealing release agent is applied to the surface of the steel sheet that has undergone primary recrystallization annealing. The annealing release agent has been specifically described above, so a repeated explanation will be omitted. The amount of annealing release agent to be applied is 1-20 g / m². 2 This can be done. If the amount of annealing separating agent applied is too small, film formation may not proceed smoothly. If the amount of annealing separating agent applied is too large, it may affect secondary recrystallization. Therefore, the amount of annealing separating agent applied can be adjusted within the aforementioned range. Next, in step (S60), the steel sheet coated with the annealing separating agent is subjected to secondary recrystallization annealing. During the secondary recrystallization annealing process, a film 20 containing boron and forsterite is formed.

[0061] During secondary recrystallization annealing, the primary crack temperature can be set to 650-750°C, and the secondary crack temperature to 1100-1250°C. The temperature can be controlled at a rate of 15°C / hr during the heating phase. Furthermore, the gaseous atmosphere can be maintained with 220-30% nitrogen and 70-80% hydrogen by volume until the primary crack step, and then a 100% hydrogen atmosphere for 15 hours before furnace cooling during the secondary crack step. Under these conditions, the coating 20 can be formed smoothly.

[0062] The step (S60) may further include a step of forming a ceramic layer 30. The ceramic layer 30 has been specifically described above, so a repeated explanation will be omitted. As a method for forming the ceramic layer 30, ceramic powder can be sprayed onto the film 20 to form the ceramic layer. Specifically, plasma spray coating, high-velocity oxy fuel spray coating, aerosol deposition, and cold spray coating methods can be applied. More specifically, a plasma spray coating method can be used in which ceramic powder is supplied to a heat source that plasmaizes a gas containing Ar, H2, N2, or He at an output of 20-300 kW to form a ceramic layer. Alternatively, as a plasma spray coating method, the ceramic layer 30 can be formed by supplying a mixture suspension of ceramic powder and solvent to a heat source that plasmaizes a gas containing Ar, H2, N2, or He at an output of 20-300 kW. In this case, the solvent can be water or alcohol.

[0063] Furthermore, as a method for forming the ceramic layer 30, a method can be used in which a ceramic layer-forming composition containing ceramic powder and metal phosphate is applied to form the ceramic layer. After forming the ceramic layer 30, magnetic domain refinement can be performed as needed.

[0064] The present invention will be described in more detail below through examples. However, these examples are merely illustrative and the present invention is not limited thereto.

[0065] Experimental Example 1: Properties of different annealing separating agent components and ceramic layer components Example 1 A slab was prepared containing 3.4 wt% silicon (Si), 0.03 wt% aluminum (Al), 0.05 wt% manganese (Mn), 0.04 wt% antimony (Sb), 0.09 wt% tin (Sn), 0.02 wt% nickel (Ni), 0.06 wt% carbon (C), and 40 wt ppm nitrogen (N), with the remainder being Fe and its unavoidable impurities. The slab was heated at 1150°C for 220 minutes, then hot-rolled to a thickness of 2.3 mm to produce a hot-rolled sheet.

[0066] After heating the hot-rolled sheet to 1120°C, maintaining the temperature at 920°C for 95 seconds, it was rapidly cooled with water, pickled, and then cold-rolled to a thickness of 0.23 mm to produce a cold-rolled sheet. After placing the cold-rolled sheet into a furnace maintained at 850°C, it was kept in a mixed atmosphere of 74% hydrogen, 25% nitrogen, and 1% dry ammonia gas for 180 seconds to simultaneously perform decarburization immersion and primary recrystallization annealing, thereby producing a primary recrystallized annealed steel sheet. As an annealing separation agent composition, 30% by weight of boron compound (BN), 3% by weight of cobalt hydroxide (Co(OH)2), 5% by weight of titanium oxide, 35% by weight of Sb2(SO4), and the remainder being magnesium oxide (MgO) were mixed with distilled water to produce a slurry. The slurry was then applied to a steel sheet that had undergone primary recrystallization annealing using a roll, and subsequently subjected to secondary recrystallization annealing.

[0067] During secondary recrystallization annealing, the primary crack temperature was set to 700°C and the secondary crack temperature to 1200°C, with a temperature increase of 15°C / hr during the heating interval. Up to 1200°C, a mixed gas atmosphere of 50% nitrogen and 50% hydrogen was maintained, and after reaching 1200°C, a 100% hydrogen gas atmosphere was maintained for 20 hours, followed by furnace cooling. Subsequently, TiO2 was supplied as ceramic powder to a heat source that generated plasma from argon (Ar) gas at an output of 250 kW, and a ceramic layer with a thickness of 0.9 μm was formed on the surface of the final annealed plate.

[0068] Examples 2 to 8 The procedure was carried out in the same manner as in Example 1, but the boron compound and metal hydroxide component in the annealing separation agent were alternated as shown in Table 1 below to form a film. In addition, a ceramic layer was formed on the surface of the boron-containing forsterite film by supplying the ceramic layer component powders summarized in Table 1 below.

[0069] Example 9 The procedure was carried out in the same manner as in Example 1, but the boron compound and metal hydroxide component were alternated as shown in Table 1 to form a film, and no ceramic layer was formed.

[0070] Example 10 The procedure was carried out in the same manner as in Example 1, but a coating was formed using an annealing separating agent composition containing 25% by weight of a boron compound, 65% by weight of magnesium oxide, 5% by weight of titanium oxide, and 35% by weight of Sb2(SO4), and no ceramic layer was formed.

[0071] Comparative Example 1 The procedure was carried out in the same manner as in Example 1, but an annealing separation agent composition containing 90% by weight of magnesium oxide, 5% by weight of titanium oxide, and 35% by weight of Sb2(SO4) was used.

[0072] Comparative Example 2 The procedure was carried out in the same manner as in Example 1, but an annealing separation agent composition containing 100% by weight of a boron compound was used.

[0073] Comparative Example 3 The procedure was carried out in the same manner as in Example 1, but an annealing separation agent composition containing 90% by weight of a boron compound, 5% by weight of titanium dioxide, and 35% by weight of Sb2(SO4) was used.

[0074] Comparative Example 4 The procedure was carried out in the same manner as in Example 1, but an annealing separation agent composition containing 15% by weight of a boron compound, 5% by weight of titanium dioxide, 35% by weight of Sb2(SO4), and 75% by weight of magnesium oxide was used.

[0075] Comparative Example 5 The procedure was carried out in the same manner as in Example 1, but an annealing separation agent composition containing 15% by weight of a boron compound, 5% by weight of titanium dioxide, 10% by weight of aluminum hydroxide, and 70% by weight of magnesium oxide was used. Directional shapes produced in the examples and comparative examples electromagnetic The elemental content within the forsterite coating on the steel sheet was analyzed using the non-destructive EPMA (Electron Probe X-ray Microanalyzer) method. Directional shapes produced in the examples and comparative examples electromagnetic Boron aggregates within the forsterite coating of steel plates were analyzed by removing the ceramic layer when a ceramic layer was formed, and observing a 400 μm × 400 μm area on the surface of the forsterite coating using EPMA (Electron Probe X-ray Micro Analyzer). Directional shapes produced in the examples and comparative examples electromagnetic The magnetic properties of the steel plate were evaluated under conditions of 1.7T and 50Hz.

[0076] W17 / 50 refers to the power loss (W / kg) that occurs when a magnetic field with a frequency of 50 Hz is magnetized with AC up to 1.7 Tesla. Here, Tesla is a unit of magnetic flux density, meaning magnetic flux per unit area. B8 is electromagnetic When a current of 800 A / m is passed through a winding around a steel plate, electromagnetic This shows the magnetic flux density (Tesla) flowing through the steel plate. Furthermore, the insulation properties were measured on the top surface of the coating using a Franklin measuring instrument, in accordance with the ASTMA717 international standard. Furthermore, adhesion is expressed as the minimum arc diameter at which the coating does not peel off when the test specimen is bent 180° while tangent to a 10-100 mm arc. Furthermore, the surface characteristics were evaluated visually to determine the degree of uniformity in color and the formation of a uniform film.

[0077] [Table 1]

[0078] [Table 2]

[0079] [Table 3]

[0080] As shown in Tables 1 to 3, it can be confirmed that the properties of Examples 1 to 10 are superior to those of Comparative Examples 1 to 5. Specifically, when the boron compound was used alone, and in Comparative Examples 2 and 3 which contained a large amount of the boron compound, severe film peeling occurred and the magnetic properties were found to be inferior. Furthermore, in Comparative Examples 1, 4, and 5 which did not contain or contained only a small amount of the boron compound, cracks occurred on the surface, and the insulation and magnetic properties were found to be inferior to those of the Examples. Among the examples, it can be confirmed that the insulating properties are further improved when an additional ceramic layer is included. In the examples, it was confirmed that the iron loss characteristics were relatively inferior when metal hydroxide was not included, and this was confirmed to be due to the suppression of ALN-based decomposition by metal hydroxide.

[0081] Figure 2 shows the directionality produced in Example 9. electromagnetic This is a scanning electron microscope (SEM) image of a coating on a steel plate. It confirms that a uniform, defect-free coating has been formed. Figure 3 shows the directionality produced in Comparative Example 2. electromagnetic This is a scanning electron microscope (SEM) image of the coating on a steel plate. It can be seen that multiple cracks have formed, which in turn have caused the surface delamination to deepen. Figure 4 shows the directionality produced in Example 3. electromagnetic This is the result of EPMA (Electron Probe Micro-Analyzer) analysis of the coating on the steel plate using element B. Figure 5 shows the directionality produced in Example 6. electromagnetic This is the result of EPMA (Electron Probe Micro-Analyzer) analysis of the coating on the steel plate using element B. Figure 6 shows the directionality produced in Comparative Example 3. electromagnetic This is the result of EPMA (Electron Probe Micro-Analyzer) analysis of the coating on the steel plate using element B. As can be seen from Figures 4 to 6, the directionality of the product manufactured in the example electromagnetic It can be confirmed that boron aggregates are properly formed within the coating of the steel plate.

[0082] Experimental Example 2: Evaluation of magnetic properties, drip rate, and noise characteristics of a 1000kVA transformer Example 11 A slab was prepared containing 3.3 wt% silicon (Si), 0.03 wt% aluminum (Al), 0.03 wt% antimony (Sb), 0.05 wt% tin (Sn), 0.02 wt% nickel (Ni), 0.05 wt% carbon (C), and 30 wt ppm nitrogen (N), with the remainder being Fe and its unavoidable impurities. The slab was heated at 1150°C for 220 minutes, then hot-rolled to a thickness of 2.3 mm to produce a hot-rolled sheet.

[0083] After heating the hot-rolled sheet to 1120°C, maintaining the temperature at 920°C for 95 seconds, it was rapidly cooled in water and pickled, and then cold-rolled to a thickness of 0.23 mm to produce a cold-rolled sheet. After placing the cold-rolled sheet into a furnace maintained at 850°C, it was kept in a mixed atmosphere of 74% by volume hydrogen, 25% by volume nitrogen, and 1% by volume dry ammonia gas for 180 seconds to simultaneously perform decarburization and primary recrystallization annealing, thereby producing a primary recrystallized annealed steel sheet. As an annealing separation agent composition, 38% by weight of a boron compound (MgB2), 3.8% by weight of nickel hydroxide, 5% by weight of titanium oxide, 35% by weight of Sb2(SO4), and the remainder being magnesium oxide (MgO) were mixed with distilled water to produce a slurry. The slurry was then applied to a steel sheet that had undergone primary recrystallization annealing using a roll, and then secondary recrystallization annealing was performed. During secondary recrystallization annealing, the primary crack temperature was set to 700°C and the secondary crack temperature to 1200°C, with a temperature increase of 15°C / hr during the heating interval. Up to 1200°C, a mixed gas atmosphere of 50% nitrogen and 50% hydrogen was maintained, and after reaching 1200°C, a 100% hydrogen gas atmosphere was maintained for 20 hours, followed by furnace cooling.

[0084] Subsequently, a ceramic layer-forming composition containing 45% by weight colloidal silica, 45% by weight monoaluminum phosphate, 5% by weight chromium oxide, and 5% by weight nickel hydroxide was stirred, and 4.5 g / m² was applied to the final annealed plate surface. 2 After coating the material in this manner, it was treated in a drying oven set to 860°C for 120 seconds, followed by laser magnetic domain refinement. A 1000kVA transformer was then fabricated and evaluated under 60Hz conditions according to the design magnetic flux density. The results are shown in Table 4 below.

[0085] Comparative Example 6 The procedure was carried out in the same manner as in Example 11, but an annealing separation agent composition containing 90% by weight of magnesium oxide, 5% by weight of titanium oxide, and 35% by weight of Sb2(SO4) was used. The infusion rate was measured using a measuring instrument in accordance with the JIS C2550 international standard. electromagnetic After stacking multiple steel plate specimens, a uniform pressure of 1 MPa was applied to the surface, and then the heights of the four sides of the specimen were precisely measured. electromagnetic The actual weight ratio due to the lamination of steel plates was measured by dividing it by the theoretical weight. The noise evaluation method is the same as the international standard IEC61672-1, but instead of negative pressure... electromagnetic Vibration data of steel plates is acquired and evaluated using noise equivalent values ​​[dBA]. electromagnetic The vibration of the steel plate is measured non-contact over time using a laser Doppler method when the magnetic field is magnetized with alternating current up to 1.7 Tesla at a frequency of 60 Hz, and the vibration pattern is measured.

[0086] [Table 4]

[0087] As shown in Table 4, it can be confirmed that the characteristics of Example 11 are significantly superior to those of Comparative Example 6.

[0088] The present invention is not limited to the embodiments described herein and can be manufactured in a variety of different forms. Those with ordinary skill in the art to which the present invention pertains will understand that the invention can be implemented in other specific forms without altering the technical concept or essential features. Therefore, the embodiments described above should be understood to be illustrative and not limiting in all respects. [Explanation of symbols]

[0089] 10 Directions electromagnetic Steel plate base material 20 Coating 30 Ceramic Layers 100 Directions electromagnetic steel plate

Claims

1. Based on a total solids content of 100% by weight, 25-80% by weight of boron compound, and The remainder contains one or more of magnesium oxide and magnesium hydroxide. The boron compound is BN, B(NO ３ ), B(OH) ３ , BPO ３ , BH ４ , BH ３ NH ３ , B ２ O ３ , LiBH ４ , Na ２ B ４ O ７ , B ２ C, and at least one of H[BF(OH) ３ , and is characterized by being included in an annealing separation agent composition for a grain-oriented electrical steel sheet.

2. The annealing separation agent composition for grain-oriented electrical steel sheets according to claim 1, further comprising 0.1 to 20% by weight of metal hydroxide.

3. The aforementioned metal hydroxide is Ni(OH) ２ Co(OH) ２ Cu(OH) ２ , Sr(OH) ２ , Ba(OH) ２ , Pd(OH) ２ In (OH) ３ , Bi(OH) ３ The annealing separation agent composition for grain-oriented electrical steel sheets according to claim 2, characterized by containing one or more of the following: and Sn(OH).

4. The annealing separation agent composition for grain-oriented electrical steel sheets according to claim 1, further comprising 0.5 to 10% by weight of ceramic powder.

5. The aforementioned ceramic powder is MnO, Al ２ O ３ SiO ２ , TiO ２ The annealing separation agent composition for grain-oriented electrical steel sheets according to claim 4, characterized by containing one or more of the following: and ZrO.

6. Sb ２ (SO ４ ) ３ , SrSO ４ and BaSO ４ The annealing separation agent composition for grain-oriented electrical steel sheets according to claim 1, characterized in that it further contains 1 to 10% by weight of one or more of the above.

7. Grain-oriented electrical steel sheet substrate, and The aforementioned grain-oriented electrical steel sheet substrate is located on one or both sides of the substrate and includes a coating containing boron and forsterite, The aforementioned film contains boron aggregates, the average particle size of the boron aggregates being 1 to 500 nm. The aforementioned grain-oriented electrical steel sheet substrate contains 2.8 to 4.5% by weight of silicon (Si), 0.020 to 0.040% by weight of aluminum (Al), 0.01 to 0.20% by weight of manganese (Mn), and 0.01 to 0.15% by weight of antimony (Sb), tin (Sn), nickel (Ni), or a combination thereof, with the remainder being Fe and other unavoidable impurities. The boron aggregates are BN, B(NO) ３ ) ３ , B(OH) ３ BPO ４ BH ３ NH ３ , B ２ O ３ LiBH ４ Na ２ B ４ O ７ , B ２ C, and H[BF(OH) ３ A grain-oriented electrical steel sheet characterized by containing one or more of the following:

8. The grain-oriented electrical steel sheet according to claim 7, characterized in that it contains 1 to 45 area percent of boron aggregates with respect to the total area of ​​the coating.

9. The grain-oriented electrical steel sheet according to claim 7, characterized in that the coating comprises 1 to 40% by weight of B, 10 to 70% by weight of Mg, 3 to 70% by weight of Si, 10 to 50% by weight of O, and Fe as the remainder.

10. The grain-oriented electrical steel sheet according to claim 7, further comprising a ceramic layer located on the aforementioned coating.

11. The grain-oriented electrical steel sheet according to claim 10, characterized in that the ceramic layer comprises ceramic powder and a metal phosphate.

12. The aforementioned ceramic powder is Al ２ O ３ SiO ２ , TiO ２ , ZrO ２ Al ２ O ３ ・TiO ２ , Y ２ O ３ , 9Al ２ O ３ ・2B ２ O ３ , BN, CrN, BaTiO ３ The grain-oriented electrical steel sheet according to claim 11, characterized by containing one or more selected from SiC and TiC.

13. Steps to prepare the steel slab, The steps include: hot-rolling the steel slab to produce a hot-rolled sheet; The steps include: cold rolling the hot-rolled sheet to produce a cold-rolled sheet; The steps of performing primary recrystallization annealing on the cold-rolled sheet, The steps include applying an annealing release agent to the surface of the primary recrystallized annealed steel sheet, and The step includes performing secondary recrystallization annealing on a steel plate to which the annealing separating agent has been applied, The annealing separating agent comprises, on a basis of 100% by weight of total solids, 25 to 80% by weight of a boron compound and the remainder being one or more of magnesium oxide and magnesium hydroxide. The boron compound is BN, B(NO) ３ ) ３ , B(OH) ３ BPO ４ BH ３ NH ３ , B ２ O ３ LiBH ４ Na ２ B ４ O ７ , B ２ C, and H[BF(OH) ３ A method for manufacturing grain-oriented electrical steel sheets, characterized by including one or more of the following:

14. The method for manufacturing grain-oriented electrical steel sheets according to claim 13, further comprising the step of forming a ceramic layer on a film containing boron and forsterite after the step of secondary recrystallization annealing.

15. The step of forming the ceramic layer is: The method for manufacturing grain-oriented electrical steel sheets according to claim 14, characterized by the step of spraying ceramic powder onto the aforementioned film to form a ceramic layer.

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