Annealing separating agent composition for grain oriented electrical steel sheet, grain oriented electrical steel sheet and method for manufacturing same

Abstract

An annealing separator according to one embodiment of the present invention comprises: 5-80 parts by weight of a nano magnesium compound having a particle diameter of less than 0.8 μm and an average particle diameter of 1-200 nm; and 5-80 parts by weight of a micro magnesium compound having a particle diameter of 0.8 μm or larger and an average particle diameter of 1-200 μm, wherein the magnesium compound includes magnesium oxide and / or magnesium hydroxide.

Description

Annealing separator composition for grain-oriented electrical steel sheet, grain-oriented electrical steel sheet, and method for manufacturing the same

[0001] One embodiment of the present invention relates to an annealing separator composition for grain-oriented electrical steel sheets, grain-oriented electrical steel sheets, and a method for manufacturing the same. Specifically, one embodiment of the present invention relates to grain-oriented electrical steel sheets having improved magnetism by appropriately controlling the particle size of a magnesium compound in an annealing separator to form an appropriate forsterite film aggregate near a forsterite film, and a method for manufacturing the same.

[0002] In general, oriented electrical steel is a steel sheet containing Si components, and the grain orientation is {110}. <001> It refers to an electrical steel sheet that has an aligned aggregate structure in the direction of rolling and has extremely excellent magnetic properties in the rolling direction.

[0003] Grain-oriented electrical steel sheets form an insulating film on a forsterite (Mg2SiO4) base film and use the difference in thermal expansion coefficient of this insulating film to apply tensile stress to the steel sheet, thereby improving core loss and reducing noise caused by magnetostriction. However, there are limitations in satisfying the level of properties of high-grade grain-oriented electrical steel sheets that are recently demanded.

[0004] Accordingly, a method of improving the surface properties of MgO by adding TiO2 powder to MgO in the step of applying an anti-adhesion agent containing MgO as a main component to improve the properties of the forsterite film in the oriented electrical steel sheet manufacturing process is proposed.

[0005] In addition, to improve the film tension, kaolinite (Al4Si4O) is added to the surface of the decarburized annealed plate. 10A method has been proposed to form a composite film composed of alumina and silica on the surface of a steel sheet by applying (OH)8) as an annealing separator and performing final annealing. However, this method is a technology to form a dual-structure composite film composed of alumina on the upper part and silica on the lower part by decomposing kaolinite, and it is difficult to control and form a uniform quality in the secondary recrystallization annealing process, and there are problems with poor adhesion due to the silica film formed on the lower part.

[0006] Another known method for improving the core loss of oriented electrical steel sheets involves removing the forsterite coating by applying a mixture of alumina powder or colloidal silica and MgCl2 as an anti-adhesion agent. However, this method has the problem that the core loss of the electrical steel sheet is actually deteriorated due to the removal of the forsterite coating, and it is difficult to form an insulating coating in a subsequent process.

[0007] One embodiment of the present invention provides an annealing separator composition for a grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet, and a method for manufacturing the same. Specifically, one embodiment of the present invention provides a grain-oriented electrical steel sheet having improved magnetism by appropriately controlling the particle size of a magnesium compound in the annealing separator to form an appropriate forsterite film aggregate near the forsterite film, and a method for manufacturing the same.

[0008] An annealing separator composition according to one embodiment of the present invention comprises 5 to 80 parts by weight of a nano magnesium compound having a particle size of less than 0.8 ㎛ and an average particle size of 1 to 200 nm and 5 to 80 parts by weight of a micro magnesium compound having a particle size of 0.8 ㎛ or more and an average particle size of 1 to 200 ㎛, wherein the magnesium compound comprises at least one of magnesium oxide and magnesium hydroxide.

[0009] The magnesium compound may be included in an amount of 50 to 95 parts by weight based on 100 parts by weight of the total solid content of the annealing separator.

[0010] The weight ratio of the nano magnesium compound and the micro magnesium compound can be 5:80 to 60:25 (nano magnesium: micro magnesium).

[0011] An annealing separator composition according to one embodiment of the present invention may further include one or more of a metal hydroxide, a ceramic powder, and a sulfate compound.

[0012] A oriented electrical steel sheet according to one embodiment of the present invention includes a oriented electrical steel sheet substrate and a film including forsterite located on one or both sides of the oriented electrical steel sheet substrate.

[0013] According to one embodiment of the present invention, a oriented electrical steel sheet has a total area of ​​forsterite aggregates independent from the film and the substrate interface of 3.2 to 7.5 ㎛ in a cross-sectional area including a steel sheet width of 25 ㎛ and a thickness direction. 2 , and the average area of ​​the forsterite aggregate is 0.1 to 1.2 ㎛. 2 am.

[0014] The total area of ​​the forsterite aggregate is 4.0 to 6.5 ㎛ 2 It could be.

[0015] The average area of ​​the forsterite aggregate is 0.2 to 0.9 ㎛ 2 It could be.

[0016] The number ratio of forsterite aggregates having a ratio of the short axis to the long axis of 0.5 or more among forsterite aggregates may be 0.38 to 0.95.

[0017] The forsterite aggregate may exist in a region (A) of 2 to 5 ㎛ in the thickness direction of the steel plate from the film surface.

[0018] When elemental analysis is performed by a glow discharge spectrometer (GDS) in the direction of the thickness of the grain-oriented electrical steel sheet from the surface of the film, the peak position of the Mg content obtained can be formed at 0.7 to 1.0 ㎛ in the direction of the thickness of the grain-oriented electrical steel sheet from the surface of the film.

[0019] The directional electrical steel sheet according to one embodiment of the present invention may have an oxidation amount of 925 to 1100 ppm.

[0020] The film may have a peel adhesion of 5 to 8 N using an ASTM C1624 scratch tester.

[0021] The oriented electrical steel substrate contains 2.0 to 7.0 wt% of silicon (Si), 0.020 to 0.040 wt% of aluminum (Al), 0.01 to 0.20 wt% of manganese (Mn), 0.01 to 0.15 wt% of phosphorus (P), 0.01 to 0.15 wt% or less of carbon (C) (excluding 0%), 0.005 to 0.05 wt% of nitrogen, and 0.01 to 0.15 wt% of antimony (Sb), tin (Sn), or a combination thereof, and the remainder may contain iron and other unavoidable impurities.

[0022] The oriented electrical steel sheet substrate may further include at least one of 0.40 wt% or less of copper (Cu), 0.001 wt% or less of sulfur (S), and 0.01 to 0.2 wt% of chromium (Cr).

[0023] A method for manufacturing a oriented electrical steel sheet according to one embodiment of the present invention comprises the steps of hot-rolling a steel slab to manufacture a hot-rolled sheet; cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; first recrystallization annealing of the cold-rolled sheet; applying an annealing separator composition on the surface of the first recrystallization annealed steel sheet; and second recrystallization annealing of the steel sheet to which the annealing separator composition has been applied.

[0024] The annealing separator composition comprises 5 to 80 parts by weight of a nano magnesium compound having a particle size of less than 0.8 ㎛ and an average particle size of 1 to 200 nm and 5 to 80 parts by weight of a micro magnesium compound having a particle size of 0.8 ㎛ or more and an average particle size of 1 to 200 ㎛, wherein the magnesium compound comprises at least one of magnesium oxide and magnesium hydroxide.

[0025] The first recrystallization annealing step may have a dew point of 58 to 70°C.

[0026] The secondary recrystallization annealing step includes a first cracking step having a cracking temperature of 650 to 750°C and a second cracking step having a cracking temperature of 1100 to 1250°C, and the temperature can be increased at 10 to 20°C / hr between the first cracking step and the second cracking step.

[0027] A directional electrical steel sheet according to one embodiment of the present invention can reduce magnetic deviation in the width direction of the steel sheet and uniformly improve magnetism in the width direction of the steel sheet.

[0028] Figure 1 is a schematic diagram schematically illustrating a cross-section of a directional electrical steel sheet according to one embodiment of the present invention.

[0029] Figure 2 is a schematic diagram schematically illustrating a cross-section of a directional electrical steel sheet according to another embodiment of the present invention.

[0030] Figure 3 shows the results of analyzing the Mg content using the GDS analysis method.

[0031] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising," as used herein, specifies particular features, regions, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0033] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0034] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0035] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0036] In one embodiment of the present invention, the inclusion of additional elements means including the remaining iron (Fe) in an amount equivalent to the additional amount of the additional elements.

[0037] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0038]

[0039] An annealing separator composition according to one embodiment of the present invention comprises 5 to 80 parts by weight of a nano magnesium compound having a particle size of less than 0.8 ㎛ and an average particle size of 1 to 200 nm and 5 to 80 parts by weight of a micro magnesium compound having a particle size of 0.8 ㎛ or more and an average particle size of 1 to 200 ㎛, wherein the magnesium compound comprises at least one of magnesium oxide and magnesium hydroxide.

[0040] Hereinafter, the annealing separator composition according to one embodiment of the present invention will be described in detail for each component.

[0041] In one embodiment of the present invention, the weight part refers to the relative weight ratio to the total solid content of the annealing separator composition. The solid content refers to the remaining component after removing volatile components such as solvent from the annealing separator composition.

[0042] An annealing separator composition according to one embodiment of the present invention comprises 5 to 80 parts by weight of a nano magnesium compound having a particle size of less than 0.8 ㎛ and an average particle size of 1 to 200 nm.

[0043] If the nano-magnesium compound is included in too little amount, the magnesium compound may not penetrate well into the base material, so that the forsterite aggregate may not be sufficiently formed and the forsterite film may not be sufficiently formed, resulting in poor adhesion. In addition, the film tension-providing ability and improvement in insulation properties may not be sufficient. If the nano-magnesium compound is included in too much amount, the annealing separator coated with the nano-magnesium compound may peel off from the surface of the material before annealing, resulting in poor overall coating properties. Therefore, the nano-magnesium compound may be included in the aforementioned content range. More specifically, the nano-magnesium compound may be included in an amount of 20 to 70 parts by weight.

[0044] The average particle size of the nano-magnesium compound may be 1 to 200 nm. If the average particle size of the nano-magnesium compound is too small, the nano-magnesium compound particles may tend to aggregate with each other, making it difficult to utilize the advantages of nano-particles. If the average particle size of the nano-magnesium compound is too large, the effect on the size distribution of the existing magnesium compound may be minimal, and the film tension-providing ability and insulation properties improvement through the addition of the nano-magnesium compound may not be sufficient. More specifically, the average particle size may be 20 to 200 nm. The average particle size of the nano-magnesium compound can be measured in a dry state through a Beta-Evaporation Transform (BET) method. In one embodiment of the present invention, the average particle size is measured separately for particles having a particle size of less than 0.8 μm.

[0045] An annealing separator composition according to one embodiment of the present invention comprises 5 to 80 parts by weight of a micro-magnesium compound having a particle size of 0.8 μm or more and an average particle size of 1 to 200 μm. If the micro-magnesium compound is contained in too little amount, the amount of nano-magnesium compound becomes relatively large, which increases the aggregation phenomenon between nano-magnesium compounds, and the applied annealing separator may fall off from the surface of the material before annealing. If the micro-magnesium compound is contained in too much amount, the magnesium compound may not diffuse well into the base material layer, so that forsterite aggregates are not formed well, and the film tension-providing ability and insulation property improvement may not be sufficient. More specifically, the micro-magnesium compound may be contained in an amount of 20 to 70 parts by weight.

[0046] The average particle size of the micro-magnesium compound is 1 to 200 ㎛. When the average particle size of the micro-magnesium compound is too small, just as the amount of nano-magnesium compound increases, the agglomeration phenomenon between nano-magnesium compounds increases, and the applied annealing separator may fall off from the material surface before annealing. When the average particle size of the micro-magnesium compound is too large, the magnesium compound does not diffuse well into the base material layer, so the forsterite aggregate is not formed well, and the film tension-providing ability and insulation properties may be inferior. More specifically, the average particle size of the micro-magnesium compound may be 5 to 150 ㎛.

[0047] The magnesium compound may include at least one of magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)2). In one embodiment of the present invention, the annealing separator composition may be in the form of a slurry for easy application to the surface of the grain-oriented electrical steel sheet substrate. When water is included as a solvent for the slurry, magnesium oxide is easily dissolved in water and may also be present in the form of magnesium hydroxide. Therefore, in one embodiment of the present invention, magnesium oxide and magnesium hydroxide are treated as one component.

[0048] The magnesium compound may be included in an amount of 50 to 95 parts by weight based on 100 parts by weight of the total solid content of the annealing separator. If the amount of the magnesium compound is too small, there may not be enough Mg for forsterite formation. If the amount of the magnesium compound is too large, the reactivity of the magnesium compound may be reduced, preventing the formation of forsterite aggregates. More specifically, the magnesium compound may be included in an amount of 75 to 90 parts by weight based on 100 parts by weight of the total solid content of the annealing separator.

[0049] The weight ratio of the nano-magnesium compound and the micro-magnesium compound may be 5:80 to 60:25 (nano-magnesium: micro-magnesium). As described above, if this weight ratio is not properly controlled, the magnesium aggregates may not be properly formed, and the film properties may be deteriorated. More specifically, the weight ratio of the nano-magnesium compound and the micro-magnesium compound may be 20:65 to 50:35 (nano-magnesium: micro-magnesium).

[0050] An annealing separator composition according to one embodiment of the present invention may further include one or more of a metal hydroxide, a ceramic powder, and a sulfate compound.

[0051] The lower melting point of metal hydroxide allows for a lower film formation temperature during the secondary recrystallization annealing process, ensuring superior surface properties. Furthermore, the forsterite film formed at low temperatures suppresses the decomposition of AlN-based inhibitors, which are crucial for secondary recrystallization formation, thereby ensuring superior magnetic quality.

[0052] In one embodiment of the present invention, the annealing separator composition may contain 0.1 to 20 parts by weight of metal hydroxide. If the metal hydroxide content is too small, problems may arise in achieving the aforementioned effects. If the metal hydroxide content is too large, the metal component may diffuse internally to form a film, resulting in uneven forsterite formation behavior.

[0053] Here, the metal hydroxide refers to a metal hydroxide other than the aforementioned magnesium hydroxide. Specifically, the metal hydroxide may include at least one 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)2.

[0054] An annealing separator composition according to one embodiment of the present invention may include 0.5 to 10 parts by weight of ceramic powder. The ceramic powder may include at least one selected from MnO, Al2O3, SiO2, TiO2, and ZrO2. When an appropriate amount of ceramic powder is further included, the insulating properties of the formed film may be further improved.

[0055] An annealing separator composition according to one embodiment of the present invention may contain 0.5 to 10 parts by weight of a sulfate compound. When an appropriate amount of the sulfate compound is contained, a grain-oriented electrical steel sheet having excellent surface gloss and very beautiful roughness can be produced. The sulfate compound may contain one or more of Sb2(SO4)3, SrSO4, and BaSO4.

[0056] The annealing separator composition may further include a solvent to ensure even dispersion and easy application of the solids. The solvent may be water, alcohol, or the like, and may be included in an amount of 300 to 1,000 parts by weight per 100 parts by weight of the solids. Thus, the annealing separator composition may be in the form of a slurry.

[0057] FIG. 1 schematically illustrates a cross-section of a directional electrical steel sheet (100) according to one embodiment of the present invention.

[0058] As shown in FIG. 1, a grain-oriented electrical steel sheet (100) according to an embodiment of the present invention includes a grain-oriented electrical steel sheet substrate (10) and a coating (20) including forsterite, which is positioned on one or both surfaces of the grain-oriented electrical steel sheet substrate (10). In FIG. 1, the coating (20) is exemplified as being positioned on one surface, but as shown in FIG. 2, the coating (20) may also be positioned on both surfaces, and in this case, the grain-oriented electrical steel sheet substrate (10) is positioned between the two coatings (20). FIG. 1 is an example of a grain-oriented electrical steel sheet (100) according to an embodiment of the present invention, and may further include additional configurations in addition to the configuration shown in FIG. 1. For example, as shown in FIG. 2, it is also possible to further include a ceramic coating (40, or insulating coating) positioned on the surface of the coating (20).

[0059] The film (20) containing forsterite is formed by a chemical reaction between the internal oxide layer (SiO2) present on the surface of the steel sheet during secondary recrystallization annealing and magnesium oxide (MgO) in the annealing separator.

[0060] In addition, as shown in Fig. 1, there are forsterite aggregates (30) independent from the film (20) and the interface of the grain-oriented electrical steel substrate (10) inside the grain-oriented electrical steel substrate (10). The forsterite aggregates (30) are formed when a part of the film (20) penetrates into the substrate (10). The forsterite aggregates (30) exist independently from the film (20), and are not separated from the film (20), but are not considered as forsterite aggregates (30) when they are connected. The film (20) and forsterite aggregates (30) are distinguished from the grain-oriented electrical steel substrate (10) in that Mg and O are concentrated in SEM-EDS mapping. Since the measurable area of ​​SEM is local, at least 5 or more points are measured and an average value is derived. In one embodiment of the present invention, by appropriately forming a film (20) and a forsterite aggregate, the film adhesion ability and insulation properties are further improved.

[0061] As shown in Fig. 1, in a cross-sectional area including a steel plate width of 25 ㎛ (horizontal direction in Fig. 1) and a thickness direction (ND direction, vertical direction in Fig. 1), the total area of ​​the forsterite aggregate (30) is 3.2 to 7.5 ㎛. 2 It can be. The total area of ​​the forsterite aggregate (30) is the sum total of the forsterite areas existing in the corresponding area. If the area of ​​the forsterite aggregate (30) is too small, problems such as reduced film tension imparting ability and adhesiveness may occur. If the area of ​​the forsterite aggregate (30) is too large, problems such as poor iron loss may occur. More specifically, the total area of ​​the forsterite aggregate (30) is 4.0 to 6.5 ㎛. 2 It can be done.

[0062] As shown in Fig. 1, in a cross-sectional area including a steel plate width of 25 ㎛ and a thickness direction, the average area of ​​the forsterite aggregate (30) is 0.1 to 1.2 ㎛. 2It can be. The average area of ​​the forsterite aggregate (30) is the average area per number of forsterite aggregates (30), and is the value obtained by dividing the total area of ​​the forsterite aggregates (30) by the total number. If the average area of ​​the forsterite aggregate (30) is too small, the iron loss may be inferior, which may be a problem. If the average area of ​​the forsterite aggregate (30) is too large, the film tension imparting ability and adhesion may be reduced, which may be a problem. More specifically, the total area of ​​the forsterite aggregate (30) is 0.2 to 0.9 ㎛. 2 It can be done.

[0063] The forsterite aggregate (30) may exist in various forms, and the number ratio of forsterite aggregates having a ratio of the short axis to the long axis of 0.5 or more among the entire forsterite aggregate (30) may be 0.38 to 0.95. The long axis refers to the longest axis among the axes passing through the forsterite aggregate (30), and the short axis refers to the shortest axis among the axes passing through the center of the forsterite aggregate (30). Forsterite aggregates made of nano-magnesium compounds tend to have a larger number ratio of forsterite aggregates having a ratio of the short axis to the long axis of 0.5 or more than that of forsterite aggregates made of micro-magnesium compounds. When there are many forsterite aggregates (30) having a ratio of the short axis to the long axis of 0.5 or more, the average area per particle is small, which increases the surface area, which is advantageous in terms of film tension-providing ability and improved adhesion. If the number of forsterite aggregates (30) having a ratio of short axis to long axis of 0.5 or more is too small, problems may arise in terms of film tension imparting ability and improved adhesion. If the number of forsterite aggregates (30) having a ratio of short axis to long axis of 0.5 or more is too large, problems may arise in terms of iron loss. More specifically, the number ratio of forsterite aggregates (30) having a ratio of short axis to long axis of 0.5 or more may be 0.5 to 0.9.

[0064] The forsterite aggregate (30) may exist in a region (A) of 2 to 5 µm in the direction of the steel plate thickness from the film surface. The region of less than 2 µm is the film (20) or a portion connected to the film (20), and it is difficult to form the forsterite aggregate (30) by penetrating beyond 5 µm.

[0065] The film (20) may have a thickness of 0.1 to 5 ㎛. If the thickness of the film (20) is too thin, the film tension-giving ability and adhesion may be reduced, and problems such as poor core loss may occur. If the thickness of the film (20) is too thick, the space factor may be reduced, and problems such as poor transformer characteristics may occur. Therefore, the thickness of the forsterite film (20) may be adjusted within the above-described range. More specifically, the thickness of the forsterite film (20) may be 0.8 to 4 ㎛. The boundary between the film (20) and the steel plate substrate (10) may be divided into a film (20) containing 5 wt% or more of Mg in the thickness direction of the steel plate and a portion containing less than 5 wt% of Mg. In the case where a ceramic film (40) is further formed on the film (20), the film can be divided into a film (20) containing 5 wt% or more of Mg and a ceramic film (40) containing less than 5 wt% of Mg, based on 5 wt% of Mg.

[0066] As shown in Fig. 3, when elemental analysis is performed by a glow discharge spectrometer (GDS) analysis method in the direction of the thickness of the grain-oriented electrical steel sheet from the surface of the film (20), the peak position of the Mg content obtained can be formed at 0.7 to 1.0 ㎛ in the direction of the thickness of the grain-oriented electrical steel sheet from the surface of the film.

[0067] The peak position is the position of the inflection point where the Mg content graph increases and then decreases. This position is the position of the maximum value of the Mg content. In one embodiment of the present invention, by forming the peak position of the Mg content at an appropriate position, a coating layer of an appropriate thickness can be formed. If the peak position of the Mg content is too low, the thickness of the coating layer may be too thin, which may be a problem. If the peak position is too high, the thickness of the coating layer may be too thick, which may be a problem. More specifically, the peak position of the Mg content may be formed at 1 to 4 ㎛ in the thickness direction of the grain-oriented electrical steel sheet from the coating surface. If a ceramic coating (40) is additionally present on the coating (20), the ceramic coating (40) may be removed and the peak position may be determined.

[0068] The grain-oriented electrical steel sheet according to one embodiment of the present invention may have an oxidation amount of 900 to 1200 ppm. The oxidation amount refers to the composition ratio of O contained in the material. If the oxidation amount is too low, there may be a problem with forsterite formation due to insufficient silicon oxide to react with the magnesium compound, which may cause problems. If the oxidation amount is too high, the magnesium compound may have difficulty penetrating into the base material, which may cause problems with forsterite formation. More specifically, the oxidation amount may be 925 to 1100 ppm. The oxidation amount can be measured using an elemental analyzer.

[0069] As described above, by appropriately forming the film (20) and the forsterite aggregate (30), the adhesion of the film (20) can be further improved. More specifically, the film (20) can have a peel adhesion of 5 to 8 N through an ASTM C1624 scratch tester. The scratch tester is a device that evaluates the peel adhesion by moving a tip on a specimen while gradually increasing the load to generate a scratch on the surface of the specimen, and then reading the load (N) at the point where the peeling of the coating layer occurs. (ASTM C1624) The peeling of the coating layer can take various forms, such as buckling spallation, wedging spallation, recovery spallation, and chipping. Among these, the film adhesion can be measured based on the initial point where the peeling width due to buckling spallation becomes as wide as the scratch width. More specifically, the film (20) can have a peel adhesion of 6 to 7 N through an ASTM C1624 scratch tester.

[0070] In one embodiment of the present invention, a directional electrical steel sheet (100) may further have a ceramic film (40) formed on the film (20). FIG. 2 illustrates an example that further includes a ceramic film (40) positioned on the film (20).

[0071] The thickness of the ceramic film (40) may be 0.5 to 5 ㎛. If the thickness of the ceramic film (40) is too thin, the insulating effect of the ceramic film (40) may be reduced. If the thickness of the ceramic film (40) is too thick, the adhesion of the ceramic film (40) may be reduced, and peeling may occur. Therefore, the thickness of the ceramic film (40) may be adjusted within the above-described range. More specifically, the thickness of the ceramic film (40) may be 0.8 to 3.2 ㎛.

[0072] The ceramic film (40) may include ceramic powder. The ceramic powder may be at least one selected from Al2O3, SiO2, TiO2, ZrO2, Al2O3·TiO2, Y2O3, 9Al2O3·2B2O3, BN, CrN, BaTiO3, SiC, and TiC. The particle size of the ceramic powder may be 2 to 900 nm. If the particle size of the ceramic powder is too small, formation of the ceramic layer may become difficult. If the particle size of the ceramic powder is too large, the surface roughness may become rough, causing surface defects. Therefore, the particle size of the ceramic powder may be adjusted within the above-mentioned range.

[0073] The ceramic powder may be in one or more shapes selected from the group consisting of spherical, plate-like, and needle-like.

[0074] The ceramic film (40) may further include a metal phosphate. The metal phosphate may include at least one selected from Mg, Ca, Ba, Sr, Zn, Al, and Mn. When the metal phosphate is further included, the insulation of the ceramic film (40) is further improved.

[0075] Metal phosphates may be compounds formed by the chemical reaction of metal hydroxides and phosphoric acid (H3PO4).

[0076] Metal phosphate is a compound formed by a 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.

[0077] Specifically, the metal atom of the metal hydroxide may be formed by a substitution reaction with phosphorus of phosphoric acid to form a single bond, double bond, or triple bond, and may be formed of a compound in which the amount of unreacted free phosphoric acid (H3PO4) is 25 wt% or less.

[0078] Metal phosphate is a compound formed by a chemical reaction of a metal hydroxide and phosphoric acid (H3PO4), and the weight ratio of the metal hydroxide to phosphoric acid may be expressed as 1:100 to 40:100.

[0079] If too much metal hydroxide is included, the chemical reaction may not be completed, causing a problem of precipitation, and if too little metal hydroxide is included, the problem of poor corrosion resistance may occur, so the range can be limited as above.

[0080] In one embodiment of the present invention, the effect is exhibited by the characteristics of the annealing separator composition and the film (20), regardless of the components of the oriented electrical steel substrate (10). Supplementary information regarding the components of the oriented electrical steel substrate (10) is as follows.

[0081]

[0082] The oriented electrical steel sheet substrate (10) contains 2.0 to 7.0 wt% of silicon (Si), 0.020 to 0.040 wt% of aluminum (Al), 0.01 to 0.20 wt% of manganese (Mn), 0.01 to 0.15 wt% of phosphorus (P), 0.01 to 0.15 wt% or less of carbon (C) (excluding 0%), 0.005 to 0.05 wt% of nitrogen, and 0.01 to 0.15 wt% of antimony (Sb), tin (Sn), or a combination thereof, and the remainder may contain iron and other unavoidable impurities.

[0083] Below, the reasons for the limitation of the components of the directional electrical steel plate substrate (10) are explained.

[0084] Si: 2.0 to 7.0 wt%

[0085] Silicon (Si) increases the resistivity of steel and reduces iron loss. However, if the Si content is too low, the steel's resistivity will decrease, which will deteriorate the iron loss characteristics. In addition, a phase transformation zone may exist during high-temperature annealing, which may cause secondary recrystallization to become unstable. If the Si content is too high, brittleness may increase, making cold rolling difficult. Therefore, the Si content can be adjusted within the aforementioned range. More specifically, Si may be included in an amount of 3.0 to 4.0 wt%.

[0086] Al: 0.020 to 0.040 wt%

[0087] Aluminum (Al) is a component that ultimately acts as an inhibitor in the form of nitrides in the form of AlN, (Al,Si)N, and (Al,Si,Mn)N. If the Al content is too low, it is difficult to expect sufficient effect as an inhibitor. In addition, if the Al content is too high, the Al-based nitrides precipitate and grow too coarsely, which may insufficiently affect the inhibitor effect. Therefore, the Al content can be adjusted within the aforementioned range. More specifically, it can include 0.025 to 0.035 wt%.

[0088] Mn: 0.01 to 0.20 wt%

[0089] Manganese (Mn), like Si, has the effect of reducing iron loss by increasing resistivity, and reacts with nitrogen introduced through nitriding with Si to form (Al,Si,Mn)N precipitates, thereby inhibiting the growth of primary recrystallized grains and causing secondary recrystallization. However, if the Mn content is too high, it promotes austenite phase transformation during hot rolling, thereby reducing the size of primary recrystallized grains and making secondary recrystallization unstable. In addition, if the Mn content is too low, as an austenite-forming element, it may increase the austenite fraction during hot reheating, thereby increasing the solid solution content of precipitates, and the effect of preventing primary recrystallized grains from becoming too large through precipitate refinement and MnS formation during reprecipitation may not occur sufficiently. Therefore, the Mn content can be adjusted within the aforementioned range. More specifically, it can be included in the range of 0.03 to 0.10 wt%.

[0090] P: 0.01 to 0.15 wt%

[0091] Phosphorus (P) promotes the growth of primary recrystallized grains, thereby increasing the secondary recrystallization temperature and forming {110} in the final product. <001> It plays a role in increasing the degree of integration of the orientation. If the primary recrystallization grains are too large, the secondary recrystallization becomes unstable, but as long as the secondary recrystallization occurs, it is advantageous for magnetism to have large primary recrystallization grains to increase the secondary recrystallization temperature. Meanwhile, P is {110} in the primary recrystallized steel sheet. <001> Not only does it reduce the iron loss of the final product by increasing the number of grains with {111} orientation, but it also reduces the iron loss of the final product by increasing the number of grains with {111} orientation in the first recrystallization plate. <112> By developing a strong collective organization, the final product {110} <001> Since the degree of integration is improved, the magnetic flux density also increases. In addition, P has the function of reinforcing the suppression force by segregating at the grain boundaries up to a high temperature of about 1000℃ during the secondary recrystallization annealing and delaying the decomposition of precipitates. Therefore, if more P is added, it can have a beneficial effect on magnetism. If too little P is added, the aforementioned effect cannot be sufficiently obtained. On the other hand, if too much P is added, the size of the primary recrystallized grains is reduced, which not only makes the secondary recrystallization unstable but also increases brittleness, which can hinder the cold rolling property. Therefore, P may be included in an amount of 0.01 to 0.04 wt%. More specifically, it may be included in an amount of 0.015 to 0.035 wt%.

[0092] C: 0.01% by weight or less

[0093] Carbon (C) is a component that does not significantly contribute to improving the magnetic properties of grain-oriented electrical steel sheets in embodiments according to the present invention, and therefore, it is desirable to remove it as much as possible. However, when it is contained above a certain level, it promotes the austenite transformation of steel during the rolling process, thereby helping to refine the hot-rolled structure during hot rolling and form a uniform microstructure. Therefore, it is desirable that the C content in the slab be 0.03 wt% or more. However, if the C content is excessive, coarse carbides are formed and it becomes difficult to remove them during decarburization, and therefore, it is desirable that it be 0.08 wt% or less in the slab. During the manufacturing process of grain-oriented electrical steel sheets, carbon is decarburized through the decarburization annealing process, and the grain-oriented electrical steel sheet substrate to be finally manufactured contains 0.01 wt% or less of C. More specifically, it may contain 0.0001 to 0.0050 wt%.

[0094] N: 0.005 to 0.050 wt%

[0095] Nitrogen (N) is an element that reacts with Al and other elements to refine grains. When these elements are appropriately distributed, it can help secure an appropriate primary recrystallization grain size by appropriately refining the structure after cold rolling as described above. However, if the content is excessive, the primary recrystallized grains are excessively refined, and as a result, the driving force for grain growth during secondary recrystallization due to the fine grains increases, which can lead to grain growth in undesirable orientations. In addition, an excessive N content is undesirable because it takes a long time to remove it during the final annealing process. Therefore, the upper limit of the nitrogen content in the slab is set to 0.005 wt%, and since the content of nitrogen dissolved during slab reheating should be 0.001 wt% or more, the lower limit of the nitrogen content in the slab is preferably set to 0.001 wt%. During the manufacturing process of oriented electrical steel sheets, some nitrogen is infiltrated through the annealing process, and the final oriented electrical steel sheets manufactured contain 0.005 to 0.05 wt% of N.

[0096] Sb, Sn or a combination thereof: 0.01 to 0.15 wt%

[0097] Antimony (Sb) and tin (Sn) are grain boundary segregation elements that hinder the movement of grain boundaries, so they act as grain growth inhibitors {110} <001> It is an important element for grain size control because it promotes the formation of Goss grains in the direction of orientation, thereby facilitating the development of secondary recrystallization. If the content of Sb and Sn alone or in combination is too low, the effect may be reduced. If the content of Sb and Sn alone or in combination is too high, grain boundary segregation may occur severely, increasing the brittleness of the steel sheet, which may cause sheet breakage during rolling. More specifically, it may contain 0.01 to 0.05 wt% of Sb and 0.01 to 0.12 wt% of Sn.

[0098] The oriented electrical steel sheet substrate may further include at least one of 0.40 wt% or less of copper (Cu), 0.001 wt% or less of sulfur (S), and 0.01 to 0.2 wt% of chromium (Cr).

[0099] Cu: 0.40 wt% or less

[0100] Copper (Cu) reacts with S to form Cu2S precipitates, acting as an inhibitor to suppress the growth of primary recrystallized grains. When added together with Mn, it forms [MnCu]S composite precipitates, thereby affecting the size of MnS precipitates. If too much Cu is added, S precipitates in the steel before Mn, making it impossible to obtain the fine MnS precipitates desired in the present invention. Therefore, it is preferable to limit the Cu content to a range of 0.40 wt% or less. More specifically, it may include 0.010 to 0.040 wt%.

[0101] S: 0.0010 wt% or less

[0102] Sulfur (S) generally reacts with Mn and Cu to form MnS or Cu2S precipitates, acting as an inhibitor to suppress the growth of primary recrystallized grains. In order to secure fine MnS precipitates, the added Mn and S must be completely dissolved under slab heating conditions of 1150℃ or lower to function as an effective inhibitor. Therefore, it is desirable to add S within the range of the amount that can react with the added Mn amount. If too much S is added, complete solid solution becomes difficult, which may result in coarse MnS precipitates. In the final grain-oriented electrical steel sheet, S may be contained in an amount of 0.0010 wt% or less. More specifically, it may be contained in an amount of 0.001 to 0.005 wt%.

[0103] Cr: 0.01 to 0.20 wt%

[0104] Chromium (Cr) is the element that reacts most quickly with oxygen to form Cr2O3 on the surface of the steel sheet. This allows the carbon component in the steel to rapidly diffuse to the surface of the steel sheet and react with oxygen in the ambient gas to form CO gas, thereby promoting decarburization. If too little Cr is added, the aforementioned effect cannot be sufficiently obtained. If too much Cr is added, it may not have a significant effect on the formation of a surface oxide layer. Therefore, the amount of Cr added is limited to 0.01 to 0.20 wt%. More specifically, it may include 0.03 to 0.15 wt%.

[0105] The remainder includes iron (Fe). In addition, inevitable impurities may be included. Unavoidable impurities refer to impurities that are inevitably mixed in during the manufacturing process of steelmaking and grain-oriented electrical steel sheets. Since inevitable impurities are widely known, a detailed description thereof is omitted. In one embodiment of the present invention, the addition of elements other than the aforementioned alloy components is not excluded, and various elements may be included within a range that does not impair the technical spirit of the present invention. When additional elements are further included, they are included in place of the remainder Fe. For example, it is possible to include at least one element among Ni, Mo, Zr, Bi, Pb, As, Ge, and Ga in the steel within the component range of the present invention.

[0106]

[0107] A method for manufacturing a grain-oriented electrical steel sheet according to one embodiment of the present invention includes the steps of: hot-rolling a steel slab to manufacture a hot-rolled sheet; cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; primary recrystallization annealing of the cold-rolled sheet; applying an annealing separator composition on the surface of the primary recrystallization annealed steel sheet; and secondary recrystallization annealing of the steel sheet to which the annealing separator composition has been applied. In one embodiment of the present invention, the effect is exhibited by the characteristics of the annealing separator composition and the film (20), regardless of the method for manufacturing the grain-oriented electrical steel sheet. Supplementary description of the method for manufacturing the grain-oriented electrical steel sheet is as follows.

[0108] First, in step (S10), a steel slab is hot-rolled. The composition of the steel slab has been specifically described with respect to the composition of the grain-oriented electrical steel sheet described above, so a repetitive description will be omitted. Before hot-rolling the steel slab, it can be heated. At this time, the slab can be heated at 1,200°C or lower using the low-temperature slab method.

[0109] Hot rolling is performed to a thickness of 1.0 to 3.5 mm, and considering the rolling load, rolling can be completed at a temperature of 850°C or higher, cooled to a temperature of 600°C or lower, and then coiled.

[0110] Hot-rolled steel sheets can be subjected to a hot-rolled sheet annealing process to recrystallize the hot-rolled deformation structure, facilitating smooth rolling to the final product thickness in the subsequent cold rolling process. Generally, it is desirable to heat the hot-rolled sheet to a temperature above 800°C for recrystallization and maintain it for a certain period of time. Annealing at multiple temperatures is also possible to control precipitate distribution and size. Hot-rolled sheet annealing can be omitted if necessary.

[0111] Next, the hot-rolled sheet is cold rolled to produce a cold-rolled sheet.

[0112] Hot-rolled steel sheets are pickled to remove the oxide layer on the steel sheet surface, and then cold-rolled. Cold rolling is a process to reduce the thickness of the steel sheet to the final product thickness. Cold rolling is performed once or more times including intermediate annealing to roll to the final product thickness. At this time, the cold rolling ratio enhances the Goss orientation density, which affects the improvement of the magnetic flux density after the final secondary recrystallization annealing, so cold rolling can be performed at a rolling ratio of at least 80%. If the cold rolling ratio is too low, the Goss orientation density is low, resulting in a decrease in the magnetic flux density of the final product. Therefore, the cold rolling ratio should be at least 80%, and the maximum rolling ratio can be rolled to the maximum rolling range depending on the rolling capacity of the rolling equipment. In addition, if the temperature of the cold-rolled steel sheet is raised to 50℃ or higher during the cold rolling process, many secondary recrystallization nuclei in the Goss orientation are generated due to work hardening by the dissolved carbon, which can improve the magnetic flux density of the final product. If the temperature of the cold-rolled steel sheet is too low, the generation of secondary recrystallization nuclei in the Goss orientation is minimal, and conversely, if it exceeds 300℃, the work hardening effect by the dissolved carbon is weakened, and the generation of secondary recrystallization nuclei in the Goss orientation is weakened. Therefore, in the cold rolling process, the steel sheet can be maintained in the temperature range of 50 to 300℃ at least once in the intermediate rolling stage. The thickness of the cold-rolled sheet after cold rolling can be 0.10 to 0.35 mm.

[0113] Next, the cold-rolled sheet is subjected to primary recrystallization annealing. At this time, the step of subjecting the cold-rolled sheet to primary recrystallization annealing may include a step of simultaneously subjecting the cold-rolled sheet to decarburization annealing and nitriding annealing, or a step of subjecting the cold-rolled sheet to decarburization annealing followed by nitriding annealing.

[0114] In the first recrystallization annealing step, the soaking temperature may be 820 to 900°C. If the temperature is too low, even if the desired amount of oxygen is reached, there may be a lack of Fe-based oxides (Fe2SiO4 or FeSiO3) that are important for the stable formation of a forsterite film as an oxide quality, or the oxide density may be insufficient. If the temperature is too high, the density of the oxide film or the formation of Fe-based oxides is advantageous, but the decarburization may be poor due to the initially formed oxide. The soaking temperature may be configured in two stages, and the first soaking temperature may be configured to 830 to 860°C, and the second soaking temperature may be configured to 850 to 890°C. In this case, the oxide quality can be further improved.

[0115] The dew point of the atmosphere during decarburization can be between 58 and 70°C. A low dew point makes it difficult for sufficient oxidation or decarburization to occur. A too high dew point can lead to rapid FeO formation in the outermost layer of the oxide film, creating an unstable oxide. More specifically, the dew point of the atmosphere during decarburization can be between 60 and 68°C.

[0116] Next, an annealing separator is applied to the surface of the steel sheet subjected to primary recrystallization annealing. Since the annealing separator has been described in detail above, a detailed explanation will be omitted.

[0117] The application amount of the annealing agent is 1 to 20 g / m 2 If the amount of annealing agent applied is too small, film formation may not occur smoothly. If the amount of annealing agent applied is too large, secondary recrystallization may be affected. Therefore, the amount of annealing agent applied can be adjusted within the above-mentioned range. The amount applied is based on the solid content.

[0118] Next, the steel plate to which the annealing separator has been applied is subjected to secondary recrystallization annealing. During the secondary recrystallization annealing process, a film (20) containing forsterite is formed.

[0119] In the secondary recrystallization annealing, the first cracking temperature can be 650 to 750°C, and the second cracking temperature can be 1100 to 1250°C. The temperature range of the temperature increase section between the first cracking and the second cracking can be controlled with a temperature increase condition of 10 to 20°C / hr. In addition, the gas atmosphere can be performed in an atmosphere containing 220 to 30 volume% of nitrogen and 70 to 80 volume% of hydrogen until the first cracking stage, and can be maintained in a 100% hydrogen atmosphere for 15 hours and then furnace cooling can be performed for the second cracking stage. Through the above-mentioned conditions, the film (20) can be smoothly formed.

[0120] Hereinafter, a step of forming a ceramic film (40) may be further included. Since the ceramic film (40) has been described in detail above, a repeated description thereof will be omitted. As a method of forming the ceramic film (40), a ceramic layer may be formed by spraying ceramic powder on the film (20). Specifically, a plasma spray coating method, a high velocity oxy fuel flame spray coating method, an aerosol deposition method, and a cold spray coating method may be applied. More specifically, a plasma spray coating method may be used in which a ceramic powder is supplied to a heat source that has been plasma-formed with an output of 20 to 300 kW with a gas containing Ar, H2, N2, or He, to form a ceramic layer. In addition, as a plasma spray coating method, a ceramic film (40) may be formed by supplying a mixture suspension of ceramic powder and a solvent to a heat source that has been plasma-formed with an output of 20 to 300 kW with a gas containing Ar, H2, N2, or He. At this time, the solvent can be water or alcohol.

[0121] In addition, as a method for forming a ceramic film (40), a method of forming a ceramic layer by applying a ceramic layer forming composition including ceramic powder and metal phosphate can be used.

[0122] After forming the ceramic film (40), domain refinement can be performed as needed.

[0123] The present invention will be described in more detail below through examples. However, these examples are intended only to illustrate the present invention and are not intended to limit the present invention.

[0124]

[0125] Example 1

[0126] A slab was prepared containing 3.4 wt% of silicon (Si), 0.03 wt% of aluminum (Al), 0.05 wt% of manganese (Mn), 0.04 wt% of antimony (Sb), 0.09 wt% of tin (Sn), and 0.02 wt% of nickel (Ni), 0.06 wt% of carbon (C), and 40 wt ppm of nitrogen (N), with the remainder being iron and other unavoidable impurities.

[0127] The slab was heated at 1150℃ for 220 minutes and then hot-rolled to a thickness of 2.3 mm to produce a hot-rolled plate.

[0128] A hot-rolled sheet was heated to 1120°C, maintained at 920°C for 95 seconds, then rapidly cooled in water, pickled, and then cold-rolled to a thickness of 0.23 mm to produce a cold-rolled sheet.

[0129] After the cold-rolled sheet was placed in a furnace maintained at 850°C, it was maintained in an atmosphere mixed with 74% by volume of hydrogen, 25% by volume of nitrogen, and 1% by volume of dry ammonia gas for 180 seconds, thereby simultaneously performing decarburization, nitriding, and primary recrystallization annealing, thereby manufacturing a steel sheet subjected to primary recrystallization annealing.

[0130] As an annealing separator composition, the components listed in Table 1 below, 5 parts by weight of metal hydroxide, 5 parts by weight of ceramic powder, and 5 parts by weight of sulfate were mixed with distilled water to prepare a slurry, and the slurry was applied to a steel sheet that had undergone primary recrystallization annealing using a roll, followed by secondary recrystallization annealing.

[0131] During the secondary recrystallization annealing, the primary cracking temperature was 700°C, the secondary cracking temperature was 1200°C, and the heating rate was 15°C / hr during the temperature increase interval therebetween. In addition, up to 1200°C, a mixed gas atmosphere of 50% by volume of nitrogen and 50% by volume of hydrogen was used, and after reaching 1200°C, it was maintained in a 100% by volume hydrogen gas atmosphere for 20 hours and then furnace cooling was performed.

[0132] The forsterite coating and forsterite aggregates were analyzed by FIB-SEM cross-sectional analysis and FIB-SEM EDS mapping. The thickness of the forsterite coating, the size of the forsterite aggregates, and the major / minor axis ratio were analyzed through cross-sectional analysis, and the forsterite aggregates were distinguished from the parent material by FIB-SEM EDS mapping. The size of the forsterite aggregates was calculated by image analyzing.

[0133] Peel adhesion was measured using an ASTM C1624 scratch tester. The scratch tester is a device that evaluates peel adhesion by moving a tip on a specimen while gradually increasing the load to create a scratch on the specimen surface, and then reading the load (N) at the point where the coating layer peels off (ASTM C1624). Peeling of the coating layer can take various forms, such as buckling spallation, wedging spallation, recovery spallation, and chipping. Among these, the film adhesion was measured based on the first point where the peeling width due to buckling spallation was as wide as the scratch width.

[0134] In addition, the peak position was measured for the Mg content obtained when elemental analysis was performed using a glow discharge spectrometer (GDS) analysis method in the thickness direction of the oriented electrical steel sheet.

[0135] Epstein specimens were cut into 10 pieces each by shearing to the size of the specimen [60 mm (width) X 300 mm (length)] and the magnetic flux density (B8) and iron loss (W 17 / 50 ) was measured.

[0136] The insulation properties were measured on the top of the coating using a Franklin measuring instrument according to the ASTM A717 international standard.

[0137] Additionally, the adhesion is expressed as the minimum arc diameter without film peeling when the specimen is bent 180° in contact with an arc of 10 to 100 mm.

[0138] Annealing separator (solid content 100 parts by weight) No. Nano magnesium compound Micro magnesium compound Hydroxide metal ceramic powder Sulfate Average particle size (nm) Content (parts by weight) Average particle size (㎛) Content (parts by weight) 120 55.080 CrMnOSb 2 20 20 5.065 NiAl 2 O 3 Sr 3 20 20 1.065 CoSiO 2 Ba 4 20 20 20 0.065 CuTiO 2 Sb 5 20 80 5.05 SrZrO 2 Sr 6 10 0 55.080 BaMnOBa 7 10 0 80 5.05 PdAl 2 O 4 Sb 8 20 0 55.080 InSiO 3 Sr 9 20 08 05.05BiTiO3Ba101205.065CrZrO3Sb11600205.065NiMnOSr122035.082CoAl2O5Ba1320825.03Cu SiO2Sb1420200.865SrTiO2Sr152020300.065BaZrO4Ba1620825.03PdMnOSb17--5.085InAl2O6Sr

[0139] No. Forsterite film Forsterite aggregate Thickness (㎛) Peak position (㎛) Oxidation amount (ppm) Total area (㎛) 2 )Average area (㎛) 2)12.80.99256.50.323.21.09507.50.133.11.010007.30.542.20.910507.00.651.50.811006.51.261.40.710005.30.872.10.810003.70.581.60.710004.80.391.70.710003. 20.9101.50.710003.90.7110.90.610002.51.5120.80.510003.51.3131.10.510002.50.9141.20.610002.20.8150.90.510001.51.5160.80.510002.72.7171.10.510002.81.3

[0140] No. Film Adhesion (ASTM C1624, N) Insulation (ASTM A717, mA) 160.32 280.51 370.57 480.25 560.43 650.47 770.35 870.58 960.61 1080.47 1130.57 1230.67 1340.64 1420.48 1510.75 1630.73 1720.52

[0141] As can be seen in Tables 1 to 3, in the case of No. 1 to 10, in which the annealing separator composition components are appropriately adjusted, it can be confirmed that forsterite aggregates are appropriately formed, and film adhesion, magnetism, and insulation properties are simultaneously excellent.

[0142] On the other hand, if the annealing separator composition components are not properly included, it can be confirmed that the film adhesion, magnetism, or insulation properties are somewhat inferior.

[0143]

[0144] The present invention is not limited to the above-described embodiments and / or examples, but can be manufactured in various different forms. Those skilled in the art will understand that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the above-described embodiments and / or examples should be understood as illustrative in all respects and not restrictive.

[0145] [Explanation of symbols]

[0146] 100: Grain-oriented electrical steel sheet, 10: Grain-oriented electrical steel sheet base,

[0147] 20: Film, 30: Forsterite aggregate,

[0148] 40: Ceramic film

Claims

1. 5 to 80 parts by weight of a nano magnesium compound having a particle size of less than 0.8 ㎛ and an average particle size of 1 to 200 nm, and Containing 5 to 80 parts by weight of a micro magnesium compound having a particle size of 0.8 μm or more and an average particle size of 1 to 200 μm, The above magnesium compound is an annealing separator composition comprising at least one of magnesium oxide and magnesium hydroxide.

2. In paragraph 1, An annealing separator composition comprising 50 to 95 parts by weight of the magnesium compound relative to 100 parts by weight of the total solid content of the annealing separator.

3. In paragraph 1, An annealing separator composition wherein the weight ratio of the nano magnesium compound and the micro magnesium compound is 5:80 to 60:

25.

4. In paragraph 1, An annealing separator composition further comprising at least one of a metal hydroxide, a ceramic powder, and a sulfate compound.

5. Directional electrical steel sheet substrate and In the grain-oriented electrical steel sheet including a film containing forsterite located on one or both sides of the grain-oriented electrical steel sheet substrate, The above oriented electrical steel sheet has a cross-sectional area including a steel sheet width and thickness direction of 25 ㎛, The total area of ​​the forsterite aggregate independent from the above film and the substrate interface is 3.2 to 7.5 ㎛. 2 And, The average area of ​​the above forsterite aggregate is 0.1 to 1.2 ㎛ 2 Directional electrical steel sheet.

6. In paragraph 5, The total area of ​​the above forsterite aggregate is 4.0 to 6.5 ㎛ 2 In, directional electrical steel sheet.

7. In paragraph 5, The average area of ​​the above forsterite aggregate is 0.2 to 0.9 ㎛ 2 In, directional electrical steel sheet.

8. In paragraph 5, Grain-oriented electrical steel sheet having a number ratio of forsterite aggregates having a ratio of the short axis to the long axis of 0.5 or more among the above forsterite aggregates of 0.38 to 0.

95.

9. In paragraph 5, Grain-oriented electrical steel sheet in which the above forsterite aggregate exists in a region of 2 to 5 ㎛ in the thickness direction of the steel sheet from the film surface.

10. In paragraph 5, Grain-oriented electrical steel sheet, wherein when element analysis is performed by a glow discharge spectrometer (GDS) in the thickness direction of the grain-oriented electrical steel sheet from the surface of the film, the peak position of the Mg content obtained is formed at a position 0.7 to 1.0 ㎛ in the thickness direction of the grain-oriented electrical steel sheet from the surface of the film.

11. In paragraph 5, Grain-oriented electrical steel sheet having an oxidation content of 925 to 1100 ppm.

12. In paragraph 5, The above film is a grain-oriented electrical steel sheet having a peel adhesion of 5 to 8 N using an ASTM C1624 scratch tester.

13. In paragraph 5, The grain-oriented electrical steel sheet substrate contains 2.0 to 7.0 wt% of silicon (Si), 0.020 to 0.040 wt% of aluminum (Al), 0.01 to 0.20 wt% of manganese (Mn), 0.01 to 0.15 wt% of phosphorus (P), 0.01 to 0.15 wt% or less of carbon (C) (excluding 0%), 0.005 to 0.05 wt% of nitrogen, and 0.01 to 0.15 wt% of antimony (Sb), tin (Sn), or a combination thereof, the remainder being iron and other unavoidable impurities.

14. In paragraph 5, The grain-oriented electrical steel sheet substrate further comprises at least one of 0.40 wt% or less of copper (Cu), 0.001 wt% or less of sulfur (S), and 0.01 to 0.2 wt% of chromium (Cr).

15. A step of hot rolling a steel slab to manufacture a hot-rolled plate; A step of manufacturing a cold rolled sheet by cold rolling the hot rolled sheet; A step of first recrystallization annealing the above cold rolled sheet; A step of applying an annealing separator composition on the surface of a steel sheet that has undergone primary recrystallization annealing; and A step of performing secondary recrystallization annealing on a steel sheet to which an annealing separator composition has been applied; A method for manufacturing a grain-oriented electrical steel sheet, wherein the annealing separator composition comprises 5 to 80 parts by weight of a nano magnesium compound having a particle size of less than 0.8 ㎛ and an average particle size of 1 to 200 nm and 5 to 80 parts by weight of a micro magnesium compound having a particle size of 0.8 ㎛ or more and an average particle size of 1 to 200 ㎛, and the magnesium compound comprises at least one of magnesium oxide and magnesium hydroxide.

16. In paragraph 15, The above first recrystallization annealing step is a method for manufacturing a grain-oriented electrical steel sheet having a dew point of 58 to 70°C.

17. In paragraph 15, The above second recrystallization annealing step is, The first cracking stage with a cracking temperature of 650 to 750 ℃ ​​and Contains a secondary cracking stage having a cracking temperature of 1100 to 1250°C, A method for manufacturing a grain-oriented electrical steel sheet, wherein the temperature is increased at a rate of 10 to 20°C / hr between the first cracking step and the second cracking step.

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