Annealing separator composition for grain-oriented electrical steel sheet, grain-oriented electrical steel sheet and method for manufacturing grain-oriented electrical steel sheet
technical field
[One]
An embodiment of the present invention relates to an annealing separator composition for a grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet, and a method for manufacturing a grain-oriented electrical steel sheet. Specifically, an embodiment of the present invention uses nickel hydroxide and cobalt hydroxide to improve the properties of the film and ultimately improve the iron loss of the material, an annealing separator composition for grain-oriented electrical steel sheet, grain-oriented electrical steel sheet and grain-oriented electrical steel sheet it's about
background
[2]
Grain-oriented electrical steel sheet is an electrical steel sheet containing Si component in the steel sheet, has a grain orientation aligned in the {110} <001> direction, and has extremely excellent magnetic properties in the rolling direction.
[3]
Recently, as grain-oriented electrical steel sheets of high magnetic flux density have been commercialized, materials with low iron loss are required. The improvement of iron loss in electrical steel sheet can be approached by four technical methods. First, the {110} <001> grain orientation including the easy magnetization axis of the grain-oriented electrical steel sheet is accurately oriented in the rolling direction; Third, there is a magnetic domain refinement method that refines the magnetic domain through chemical and physical methods, and finally, there are surface properties improvement or surface tension application by chemical methods such as surface treatment and coating.
[4]
In particular, for improving surface properties or imparting surface tension, a method of forming a primary film and an insulating film has been proposed. As a primary film, forsterite (2MgO·SiO 2 ) formed by the reaction of silicon oxide (SiO 2 ) generated on the material surface during the primary recrystallization annealing process of electrical steel sheet material and magnesium oxide (MgO) used as an annealing separator . The layers are known. The primary film formed during high-temperature annealing should have a uniform color without defects in appearance, and functionally prevent fusion between the plate and the plate in the coil state, and the tensile stress on the material due to the difference in the coefficient of thermal expansion between the material and the primary film. It is possible to bring about the effect of improving the iron loss of the material by giving it.
[5]
Recently, as the demand for low iron loss grain-oriented electrical steel sheet has increased, high tension of the primary coating has been pursued. In fact, there are various processes to improve the properties of the high tension insulating coating so that the magnetic properties of the final product can be greatly improved. A method of controlling factors is being tried. In general, the tension applied to the material by the primary film and the secondary insulation or tension coating is usually 1.0 kgf/mm 2 or more, and at this time, it is known that the ratio of tension occupied by each is approximately 50/50. Therefore, the film tension by forsterite is about 0.5 kgf/mm 2 , and if the film tension by the primary film is improved compared to the present, not only the iron loss of the material but also the transformer efficiency can be improved.
[6]
In contrast, a method for obtaining a high-tensile film by introducing a halogen compound into an annealing separator has been proposed. In addition, a technique for forming a mullite film with a low coefficient of thermal expansion by applying an annealing separator containing kaolinite as the main component has been proposed. In addition, methods for enhancing interfacial adhesion by introducing rare elements Ce, La, Pr, Nd, Sc, Y, etc. have been proposed. However, the annealing separator additive suggested by these methods is very expensive and has a problem in that workability is significantly lowered to be applied to the actual production process. In particular, when a material such as kaolinite is prepared as a slurry for use as an annealing separator, its applicability is poor, so it is very insufficient as an annealing separator.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[7]
An 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 a grain-oriented electrical steel sheet. Specifically, an embodiment of the present invention provides an annealing separator composition for grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet, and a method of manufacturing a grain-oriented electrical steel sheet, which are excellent in adhesion and film tension to improve the iron loss of the material.
means of solving the problem
[8]
The annealing separator composition for grain-oriented electrical steel sheet according to an embodiment of the present invention contains 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide; and 30 to 250 parts by weight of a metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide; Including, the metal hydroxide has an average particle diameter of 0.01 to 80 μm.
[9]
The metal hydroxide may include 30 to 250 parts by weight of the nickel hydroxide.
[10]
The metal hydroxide may include 30 to 150 parts by weight of nickel hydroxide and 30 to 150 parts by weight of cobalt hydroxide.
[11]
The annealing separator composition for grain-oriented electrical steel sheet according to an embodiment of the present invention may further include 1 to 10 parts by weight of ceramic powder.
[12]
The ceramic powder may be at least one selected from Al 2 O 3 , SiO 2 , TiO 2 and ZrO 2 .
[13]
The annealing separator composition for grain-oriented electrical steel sheet according to an embodiment of the present invention may further include 50 to 500 parts by weight of a solvent.
[14]
The grain-oriented electrical steel sheet according to an embodiment of the present invention may include one or more composites of Fe-Ni, Fe-Co, or Fe-Ni-Co on one or both sides of the grain-oriented electrical steel sheet substrate.
[15]
With respect to the cross-section in the thickness direction of the steel sheet, the average particle diameter of at least one composite of Fe-Ni, Fe-Co, or Fe-Ni-Co may be 1 to 100 nm.
[16]
With respect to the cross section in the thickness direction of the steel sheet, the area occupied by the composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co with respect to the film area may be 0.1 to 10%.
[17]
The film may include 0.1 to 40% by weight of at least one of Ni and Co, 40 to 85% by weight of Mg, 0.1 to 40% by weight of Si, 10 to 55% by weight of O, and Fe as the balance.
[18]
The coating may further include a Mg-Si composite.
[19]
The film may have a thickness of 0.1 to 10 μm.
[20]
An oxide layer may be formed from the interface between the film and the substrate to the inside of the substrate.
[21]
The oxide layer may include a composite of one or more of Fe-Ni, Fe-Co, or Fe-Ni-Co.
[22]
The grain-oriented electrical steel sheet substrate is silicon (Si): 2.0 to 7.0 wt%, aluminum (Al): 0.020 to 0.040 wt%, manganese (Mn): 0.01 to 0.20 wt%, phosphorus (P) 0.01 to 0.15 wt%, carbon ( C) 0.01% by weight or less (excluding 0%), N: 0.005 to 0.05% by weight and 0.01 to 0.15% by weight of antimony (Sb), tin (Sn), or a combination thereof, the balance being Fe and others It may contain unavoidable impurities.
[23]
A method of manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of preparing a steel slab; heating the steel slab; Hot rolling the heated steel slab to manufacture a hot-rolled sheet; cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; primary recrystallization annealing the cold-rolled sheet; applying an annealing separator on the surface of the steel sheet subjected to the primary recrystallization annealing; and performing secondary recrystallization annealing of the steel sheet coated with the annealing separator.
[24]
The annealing separator is 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide; and 30 to 250 parts by weight of a metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide; Including, the metal hydroxide has an average particle diameter of 0.01 to 80 μm.
[25]
The primary recrystallization annealing of the cold-rolled sheet may include decarburization annealing and nitridation annealing of the cold-rolled sheet at the same time, or after decarburization annealing, nitridation annealing.
Effects of the Invention
[26]
According to one embodiment of the present invention, it is possible to provide a grain-oriented electrical steel sheet having excellent iron loss and magnetic flux density, and excellent film adhesion and insulation, and a method for manufacturing the same.
[27]
According to one embodiment of the present invention, nickel or cobalt is present in the primary film, and also nickel or cobalt partially penetrates into the grain-oriented electrical steel sheet substrate to form a Fe-Ni, Fe-Co, Fe-Ni-Co composite By doing so, it is possible to provide a grain-oriented electrical steel sheet having improved magnetization and improved iron loss, particularly high-frequency iron loss, and a method for manufacturing the same.
Brief description of the drawing
[28]
1 is a schematic side cross-sectional view of a grain-oriented electrical steel sheet according to an embodiment of the present invention.
[29]
2 is a focused ion beam-scanning electron microscope (FIB-SEM) analysis result of the film of the grain-oriented electrical steel sheet prepared in Example 5;
[30]
3 is an electron transmission microscope analysis result of the Fe-Ni crystal in the film of the grain-oriented electrical steel sheet prepared in Example 5.
[31]
4 is an electron probe microanalysis (EPMA) analysis result for Fe-Ni in the film of the grain-oriented electrical steel sheet prepared in Example 5.
Modes for carrying out the invention
[32]
The terminology used herein is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and includes the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.
[33]
When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be involved in between. In contrast, when a part refers to being “directly above” another part, the other part is not interposed therebetween.
[34]
Also, in the present invention, 1 ppm means 0.0001%.
[35]
In an embodiment of the present invention, when an additional component is further included in the composition including the remainder, the meaning means that the remainder is included by replacing the additional amount of the additional component.
[36]
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 art to which the present invention belongs. Commonly used terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, they are not interpreted in an ideal or very formal meaning.
[37]
Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.
[38]
Annealing separator composition for grain-oriented electrical steel sheet according to an embodiment of the present invention is an annealing separator composition for grain-oriented electrical steel sheet according to an embodiment of the present invention 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide; and 30 to 250 parts by weight of a metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide; include Here, parts by weight means a relative weight of each component.
[39]
The annealing separator composition for grain-oriented electrical steel sheet according to an embodiment of the present invention is a reactive material in addition to magnesium oxide (MgO), which is one of the components of the conventional annealing separator composition, nickel hydroxide (Ni(OH) 2 ) and cobalt hydroxide (Co) (OH) 2 ). As such, by adding metal hydroxide, a portion reacts with silica formed on the surface of the substrate to form a composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co, thereby facilitating magnetization and ultimately directional electricity Improves iron loss of steel plate. In particular, it improves the high-frequency iron loss of grain-oriented electrical steel sheet.
[40]
A composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co, particularly permalloy, generally has a characteristic of having a very high magnetic permeability in a low magnetic field. For this reason, in one embodiment of the present invention, magnetic properties are imparted to the primary film to improve iron loss, particularly high-frequency iron loss. In addition, this effect ultimately makes it possible to manufacture a high-efficiency transformer with low power loss.
[41]
In the manufacturing process of grain-oriented electrical steel sheet, when the cold-rolled sheet passes through a heating furnace controlled in a wet atmosphere for primary recrystallization, Si with the highest oxygen affinity in the steel reacts with oxygen supplied from the steam in the furnace to form SiO 2 on the surface. do. Thereafter, as oxygen penetrates into the steel, an Fe-based oxide is produced. SiO 2 thus formed forms a forsterite (Mg 2 SiO 4 ) layer through a chemical reaction as shown in Reaction Formula 1 below with magnesium oxide or magnesium hydroxide in the annealing separator .
[42]
[Scheme 1]
[43]

[44]
That is, the electrical steel sheet that has undergone primary recrystallization annealing is subjected to secondary recrystallization annealing, that is, high temperature annealing, after applying magnesium oxide slurry as an annealing separator. The forsterite layer prevents the material from shrinking. When the coefficient of thermal expansion of the forsterite film is very small compared to that of the material, the residual stress σ RD in the rolling direction can be expressed by the following equation.
[45]

[46]
here
[47]
△T= the temperature difference between the secondary recrystallization annealing temperature and room temperature (℃),
[48]
α Si-Fe = coefficient of thermal expansion of the material,
[49]
α C = coefficient of thermal expansion of the primary coating,
[50]
E c = average value of the primary film elasticity (Young's Modulus)
[51]
δ = thickness ratio of material and coating layer,
[52]
ν RD = Poisson's ratio in the rolling direction
[53]
indicates
[54]
From the above formula, the tensile stress improvement coefficient by the primary film includes the difference in the thickness of the primary film or the coefficient of thermal expansion between the substrate and the film. The tensile stress can be increased by increasing the coefficient difference. However, since the annealing separator is limited to magnesium oxide, there is a limit in improving the film tension by increasing the difference in thermal expansion coefficient or increasing the Young's Modulus value.
[55]
In an embodiment of the present invention, in order to overcome the physical limitations of pure forsterite, a high-temperature annealing process by adding metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide as reactive materials in addition to magnesium oxide (MgO) Medium diffusion and reaction with Fe present on the surface of the substrate thus diffused to form a composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co to induce a permalloy-forming effect that conventional electrical steel sheets do not have did. Permalloy can ultimately help facilitate magnetization, and ultimately serves to reduce the iron loss of the material by this effect.
[56]
Hereinafter, the annealing separator composition according to an embodiment of the present invention will be described in detail for each component.
[57]
In an embodiment of the present invention, the annealing separator composition includes 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide. In one embodiment of the present invention, the annealing separator composition may be present 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 of the slurry, magnesium oxide is easily dissolved in water and may exist in the form of magnesium hydroxide. Therefore, in an embodiment of the present invention, magnesium oxide and magnesium hydroxide are treated as one component. The meaning of including 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide means that when magnesium oxide is included alone, 100 parts by weight of magnesium oxide is included, and when magnesium hydroxide is included alone, magnesium hydroxide is included in 100 parts by weight When including part and magnesium oxide and magnesium hydroxide are included at the same time, it means to include 100 parts by weight in the total amount.
[58]
The activation degree of magnesium oxide may be 400 to 3000 seconds. When the activation degree of magnesium oxide is too large, a problem of leaving a spinel-based oxide (MgO·Al 2 O 3 ) on the surface after the secondary recrystallization annealing may occur. When the activation degree of magnesium oxide is too small, it may not react with the oxide layer and thus a film may not be formed. Therefore, it is possible to control the degree of activation of magnesium oxide within the above-described range. In this case, the degree of activation means the ability of the MgO powder to cause a chemical reaction with other components. The degree of activation is measured as the time it takes for MgO to completely neutralize a certain amount of citric acid solution. If the activation level is high, the neutralization time is short, and if the activation level is low, it can be said that it is high. Specifically, it is measured as the time it takes for the solution to change from white to pink when 2 g of MgO is added to 100 ml of a 0.4N citric acid solution added with 2 ml of 1% phenolphthalein reagent at 30° C. and stirred.
[59]
In an embodiment of the present invention, the annealing separator composition includes 30 to 250 parts by weight of metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide. In one embodiment of the present invention, in an embodiment of the present invention, it is introduced into the annealing separator composition in the form of having a reactive hydroxyl group (-OH) in the nickel or cobalt component system. In the case of nickel hydroxide or cobalt hydroxide, it is known that the atomic size is slightly larger than that of magnesium oxide, which is the main component of the annealing separator. Therefore, in the secondary recrystallization annealing, when the diffusion phenomenon occurs to the oxide layer existing on the surface of the material in competition with magnesium oxide, magnesium oxide Contrasting diffusion rate is slightly slower. In this case, Mg partially dissociated from magnesium oxide reacts with silica oxide present on the material surface to form a Mg-Si complex, that is, forsterite, while nickel or cobalt reacts with iron (Fe) present on the material surface. to form a Fe-Ni or Fe-Ni-Co composite.
[60]
Therefore, in an embodiment of the present invention, the diffusion of nickel and cobalt reacted with iron present on the surface of the substrate to form a Fe-Ni, Fe-Co, or Fe-Ni-Co composite, thereby induced permalloy formation effect. Permalloy can ultimately help facilitate magnetization, and ultimately serves to reduce the iron loss of the material by this effect.
[61]
Unlike the above-mentioned nickel hydroxide or cobalt hydroxide, general metal hydroxide, especially aluminum hydroxide, has excellent reaction with SiO 2 or MgO-based oxide, making it easy to form Al-Si, Al-Mg, or Al-Si-Mg composite And the composite thus formed plays a role in lowering the thermal expansion coefficient of the grain-oriented electrical steel sheet primary film or improving the elastic modulus, ultimately improving the film tension. On the other hand, since it has low reactivity with Fe oxide, a composite such as Fe-Al is not easily formed, and even if Fe-Al is formed, magnetization is not achieved unlike Fe-Ni, Fe-Co or Fe-Ni-Co composite It doesn't help much to make it easier. After all, when a general metal hydroxide other than nickel hydroxide or cobalt hydroxide is added, the effect is not large on the improvement of high-frequency iron loss.
[62]
The metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide is included in an amount of 30 to 250 parts by weight based on 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide. When the metal hydroxide is included too little, it is difficult to sufficiently obtain the effect of the above-described addition of the metal hydroxide. If too much metal hydroxide is included, the applicability of the annealing separator composition may deteriorate. Therefore, the metal hydroxide may be included in the above-described range. More specifically, 40 to 200 parts by weight of metal hydroxide may be included. More specifically, it may contain 50 to 150 parts by weight of metal hydroxide.
[63]
The metal hydroxide may include at least one of nickel hydroxide and cobalt hydroxide. That is, the metal hydroxide may include only nickel hydroxide, only cobalt hydroxide, or include nickel hydroxide and cobalt hydroxide. When only nickel hydroxide is included, 30 to 250 parts by weight of nickel hydroxide may be included. When only cobalt hydroxide is included, 30 to 250 parts by weight of cobalt hydroxide may be included. When nickel hydroxide and cobalt hydroxide are included, 30 to 250 parts by weight of nickel hydroxide and cobalt hydroxide may be included. More specifically, 30 to 150 parts by weight of nickel hydroxide and 30 to 150 parts by weight of the cobalt hydroxide may be included.
[64]
The average particle size of the metal hydroxide may be 0.01 to 80㎛. When the average particle size is too small, diffusion mainly occurs, and it may be difficult to form a composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co in the film. When the average particle size is too large, diffusion into the substrate is difficult, and the effect of improving the film tension may be significantly reduced.
[65]
When nickel hydroxide and cobalt hydroxide are included, the average particle size of the metal hydroxide may be 0.01 to 80 μm. That is, even if the average particle diameter of nickel hydroxide or cobalt hydroxide alone is outside the above range, if the average particle diameter of all metal hydroxides satisfies the above range, it is considered to fall within the scope of the present invention. More specifically, when nickel hydroxide and cobalt hydroxide are included, the average particle size of nickel hydroxide may be 0.01 to 80 μm, and the average particle size of cobalt hydroxide may be 0.01 to 80 μm.
[66]
The annealing separator composition for grain-oriented electrical steel sheet may further include 1 to 10 parts by weight of the ceramic powder based on 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide. The ceramic powder may be at least one selected from Al 2 O 3 , SiO 2 , TiO 2 and ZrO 2 . When the ceramic powder is further included in an appropriate amount, the insulating properties of the film may be further improved. Specifically, the ceramic powder may further include TiO 2 .
[67]
The annealing separator composition may further include a solvent for uniform dispersion of solids and easy application. As the solvent, water, alcohol, etc. may be used, and 50 to 500 parts by weight may be included based on 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide. As such, the annealing separator composition may be in the form of a slurry.
[68]
The grain-oriented electrical steel sheet 100 according to an embodiment of the present invention is a film including one or more composites of Fe-Ni, Fe-Co, or Fe-Ni-Co on one or both sides of the grain-oriented electrical steel sheet substrate 10 ( 20) is formed. 1 is a schematic side cross-sectional view of a grain-oriented electrical steel sheet according to an embodiment of the present invention. 1 shows a case in which the film 20 is formed on the upper surface of the grain-oriented electrical steel sheet substrate 10 .
[69]
As described above, the coating film 20 according to an embodiment of the present invention is obtained by adding appropriate amounts of magnesium oxide/magnesium hydroxide and nickel hydroxide/cobalt in the annealing separator composition, so that one of Fe-Ni, Fe-Co or Fe-Ni-Co one or more complexes. By including a composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co, the thermal expansion coefficient is lowered and the film tension is improved compared to the case of including only forsterite in the prior art. In addition, by inducing the permalloy formation effect, the iron loss of the grain-oriented electrical steel sheet 100 is improved, particularly, the high frequency iron loss. Since this has been described above, a redundant description thereof will be omitted.
[70]
The film 20 may further include an Mg-Si composite, an Al-Mg composite, or an Al-Si composite in addition to the aforementioned composite.
[71]
With respect to the cross section in the thickness direction (z direction) of the steel sheet 100, the average particle diameter of at least one composite of Fe-Ni, Fe-Co, or Fe-Ni-Co may be 1 to 100 nm. The cross-section in the thickness direction (z-direction) means all cross-sections including the rolling surface normal direction (ND direction), and specifically, may be a rolling-direction vertical surface (RD surface). In this case, the particle diameter means the diameter of the circle, assuming a circle having the same area as the area occupied by the composite. If the average particle diameter of the composite is too small, the intended effect of forming permalloy may not be sufficient. If the average particle diameter of the composite is too large, the film tension may deteriorate. More specifically, the average particle diameter of the composite may be 5 to 30 nm.
[72]
With respect to the cross section in the thickness direction of the steel sheet, the area occupied by the composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co with respect to the film area may be 0.1 to 10%. If the occupied area of ​​the composite is too small, the intended permalloy forming effect may not be sufficient. If the occupied area of ​​the composite is too large, the film tension may deteriorate. More specifically, the occupied area of ​​the composite may be 0.5 to 5%.
[73]
The content of at least one composite of Fe-Ni, Fe-Co, or Fe-Ni-Co may be 0.1 to 40 wt%. If the content of the complex is too small, the intended permalloy forming effect may not be sufficient. If the content of the composite is too large, the film tension may deteriorate. More specifically, the occupied area of ​​the composite may be 1 to 15% by weight.
[74]
The element composition in the film 20 is 0.1 to 40% by weight of at least one of Ni and Co, 40 to 85% by weight of Mg, 0.1 to 40% by weight of Si, 10 to 55% by weight of O, and Fe The remainder may be included. The above-described Ni, Co, Mg, Si, and Fe elemental compositions are derived from components in the substrate and the annealing separator component. In the case of O, it may permeate during the heat treatment process. It may further contain other impurity components, such as carbon (C).
[75]
The film 20 may have a thickness of 0.1 to 10 μm. If the thickness of the film 20 is too thin, the film tension imparting ability may be lowered, which may cause a problem of poor iron loss. If the thickness of the film 20 is too thick, the adhesiveness of the film 20 is inferior, and peeling may occur. Accordingly, the thickness of the film 20 can be adjusted within the above-described range. More specifically, the thickness of the film 20 may be 0.8 to 6 μm.
[76]
The film 20 may further include an Mg-Si composite. In this case, the Mg-Si composite may be forsterite (Mg 2 SiO 4 ).
[77]
As shown in FIG. 1 , the oxide layer 11 may be formed from the interface between the coating film 20 and the substrate 10 to the interior of the substrate 10 . The oxide layer 11 is a layer containing 0.01 to 0.2 wt% of O, and is distinguished from the rest of the substrate 10 containing less O.
[78]
As described above, in one embodiment of the present invention, by adding metal hydroxide to the annealing separator composition, nickel and cobalt are diffused into the oxide layer 11 to form Fe-Ni, Fe-Co or Fe-Ni-Co in the oxide layer 11 . to form a complex of one or more of The composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co improves iron loss, particularly high-frequency iron loss, through the permalloy effect similarly to the composite in the film 20 .
[79]
In an embodiment of the present invention, the effects of the annealing separator composition and the coating film 20 appear irrespective of the components of the grain-oriented electrical steel sheet substrate 10 . Supplementary description of the components of the grain-oriented electrical steel sheet substrate 10 as follows.
[80]
The grain-oriented electrical steel sheet substrate is silicon (Si): 2.0 to 7.0 wt%, aluminum (Al): 0.020 to 0.040 wt%, manganese (Mn): 0.01 to 0.20 wt%, phosphorus (P) 0.01 to 0.15 wt%, carbon ( C) 0.01% by weight or less (excluding 0%), N: 0.005 to 0.05% by weight and 0.01 to 0.15% by weight of antimony (Sb), tin (Sn), or a combination thereof, the balance being Fe and others It may contain unavoidable impurities. Since the description of each component of the grain-oriented electrical steel sheet substrate 10 is the same as generally known content, a detailed description is omitted.
[81]
A method of manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of preparing a steel slab; heating the steel slab; Hot rolling the heated steel slab to manufacture a hot-rolled sheet; cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; primary recrystallization annealing the cold-rolled sheet; applying an annealing separator on the surface of the steel sheet subjected to the primary recrystallization annealing; and performing secondary recrystallization annealing of the steel sheet coated with the annealing separator. In addition, the method of manufacturing a grain-oriented electrical steel sheet may further include other steps.
[82]
First, in step S10, a steel slab is prepared.
[83]
Next, the steel slab is heated. At this time, the slab heating can be heated by a low-temperature slab method at 1,200 ° C or less.
[84]
Next, the heated steel slab is hot-rolled to manufacture a hot-rolled sheet. After the step, the manufactured hot-rolled sheet may be hot-rolled and annealed.
[85]
Next, a hot-rolled sheet is cold-rolled, and a cold-rolled sheet is manufactured. In the step, cold rolling may be performed once, or cold rolling may be performed two or more times including intermediate annealing.
[86]
Next, the cold-rolled sheet is subjected to primary recrystallization annealing. In the primary recrystallization annealing process, the cold-rolled sheet may be simultaneously subjected to decarburization annealing and nitridation annealing, or may include a step of nitriding annealing after decarburization annealing.
[87]
Next, on the surface of the steel sheet subjected to the primary recrystallization annealing, an annealing separator is applied. Since the annealing separator has been specifically described above, a repeated description will be omitted.
[88]
The application amount of the annealing separator may be 6 to 20 g/m 2 . If the application amount of the annealing separator is too small, the film formation may not be smoothly performed. If the application amount of the annealing separator is too large, it may affect secondary recrystallization. Therefore, the application amount of the annealing separator can be adjusted within the above-described range.
[89]
After applying the annealing separator, drying may be further included. The drying temperature may be 300 to 700 °C. If the temperature is too low, the annealing separator may not be easily dried. If the temperature is too high, it may affect secondary recrystallization. Therefore, the drying temperature of the annealing separator can be adjusted in the above-described range.
[90]
Next, the steel sheet coated with the annealing separator is subjected to secondary recrystallization annealing. Film 20 containing at least one composite of Mg-Si forsterite, Fe-Ni, Fe-Co, or Fe-Ni-Co on the outermost surface by the annealing separator component and silica reaction during secondary recrystallization annealing this is formed In addition, oxygen permeates with nickel and cobalt into the substrate 10 to form the oxide layer 11 .
[91]
The secondary recrystallization annealing may be performed at a temperature increase rate of 18 to 75 °C/hr in a temperature range of 700 to 950 °C, and a temperature increase rate of 10 to 15 °C/hr in a temperature range of 950 to 1200 °C. By adjusting the temperature increase rate in the above-described range, the film 20 can be smoothly formed. In addition, the process of increasing the temperature of 700 to 1200 ℃ is carried out in an atmosphere containing 20 to 30% by volume of nitrogen and 70 to 80% by volume of hydrogen, and after reaching 1200 ℃, it can be carried out in an atmosphere containing 100% by volume of hydrogen. have. By controlling the atmosphere in the above-described range, the film 20 can be smoothly formed.
[92]
Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.
[93]
Example
[94]
Si:3.2%, C:0.055%, Mn:0.12%, Al:0.026%, N: 0.0042%, S: 0.0045%, Sn: 0.04%, Sb: 0.03%, P: 0.03%, and residue by weight% A steel slab containing Fe and unavoidable impurities was prepared as a wealth.
[95]
The slab was heated at 1150° C. for 220 minutes and then hot-rolled to a thickness of 2.8 mm to prepare a hot-rolled sheet.
[96]
After heating the hot-rolled sheet to 1120° C. and maintaining it 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 prepare a cold-rolled sheet.
[97]
After the cold-rolled sheet was put into a furnace maintained at 875°C, it was held for 180 seconds in a mixed atmosphere of 74 vol % hydrogen, 25 vol % nitrogen, and 1 vol % dry ammonia gas for simultaneous decarburization and nitridation.
[98]
As an annealing separator composition, an annealing separator prepared by mixing 100 g of magnesium oxide having an activation degree of 500 seconds and 250 g of water in a solid mixture of nickel hydroxide and cobalt hydroxide in the amounts listed in Table 1 below was prepared.
[99]
10 g/m 2 of an annealing separator was applied, and secondary recrystallization annealing was performed on a coil. During the secondary recrystallization annealing, the primary cracking temperature was 700 ℃, the secondary cracking temperature was 1200 ℃, and the temperature increase condition of the temperature increase section was 45 ℃/hr in the temperature section of 700 to 950℃, and in the temperature section of 950 to 1200℃ It was set as 15 degreeC/hr. On the other hand, the soaking time at 1200°C was 15 hours. The atmosphere during the secondary recrystallization annealing was a mixed atmosphere of 25 vol% nitrogen and 75 vol% hydrogen until 1200 °C, and after reaching 1200 °C, it was maintained in a 100 vol% hydrogen atmosphere and then furnace cooled.
[100]
Table 1 summarizes the components of the annealing separator applied to the present invention. Table 2 below summarizes the improvement in tension, adhesion, iron loss, magnetic flux density, and iron loss after secondary recrystallization annealing after applying the annealing separator prepared as shown in Table 1 to the specimen.
[101]
In addition, the film tension is obtained by measuring the radius of curvature (H) of the specimen generated after removing the coating on one side of the double-coated specimen and substituting the value into the following equation.
[102]

[103]
E c = film elasticity (Young's Modulus) value
[104]
ν RD = Poisson's ratio in the rolling direction
[105]
T: thickness before coating
[106]
t: thickness after coating
[107]
I: Specimen length
[108]
H: radius of curvature
[109]
In addition, adhesion is expressed by the minimum arc diameter without film peeling when the specimen is bent 180° in contact with a 10 to 100 mm arc.
[110]
The iron loss and magnetic flux density were measured using a single sheet measurement method, and the iron loss (W 17/50 ) means the power loss that occurs when a magnetic field with a frequency of 50 Hz is magnetized up to 1.7 Tesla. The iron loss (W10/400) means the power loss that occurs when a magnetic field with a frequency of 400 Hz is magnetized up to 1.0 Tesla. The iron loss (W5/1000) means the power loss that occurs when a magnetic field with a frequency of 1000 Hz is magnetized to 0.5 Tesla in alternating current.
[111]
The magnetic flux density (B 8 ) represents the value of the magnetic flux density flowing through the electrical steel sheet when a current of 800 A/m is applied to the winding wound around the electrical steel sheet.
[112]
The iron loss improvement rate was calculated as ((normal material iron loss - Example iron loss)/ normal material iron loss) × 100 based on the typical example using the MgO annealing separator.
[117]
As shown in Tables 1 and 2, when nickel hydroxide and cobalt hydroxide having an appropriate particle size are added to the annealing separator in appropriate amounts, it can be confirmed that the magnetic properties, particularly high-frequency iron loss, are improved compared to the case where it is not.
[118]
It can be seen that Comparative Materials 1 to 4 use nickel hydroxide and cobalt hydroxide having too large average particle diameters, so that nickel and cobalt do not properly diffuse into the substrate, and magnetic properties are relatively poor.
[119]
Comparative material 5 contains a small amount of nickel hydroxide and cobalt hydroxide, so it can be seen that the magnetic properties are relatively poor.
[120]
In Comparative Material 6, the iron loss (W17/50) was somewhat improved due to the addition of aluminum hydroxide, but it was confirmed that the high frequency iron loss (W10/400, W5/1000) was inferior.
[121]
In FIG. 2, a focused ion beam-scanning electron microscope (FIB-SEM) analysis result of the film of the grain-oriented electrical steel sheet prepared in Example 5 is shown. As shown in FIG. 2 , cross-sections of the composite appearing as Fe-Ni are confirmed in the middle of the film. The average particle diameter of the Fe-Ni composite was 30 nm, and the area fraction was analyzed to be 5%.
[122]
3 is an electron transmission microscope analysis result of the Fe-Ni crystal in the film of the grain-oriented electrical steel sheet prepared in Example 5. As shown in FIG. 3 , it can be confirmed that Fe-Ni is formed as a crystalline compound. As such, in one embodiment of the present invention, it can be confirmed that nickel hydroxide added as an annealing separator diffuses into the oxide layer on the surface and reacts with Fe to form a Fe-Ni crystalline composite.
[123]
4 is an electron probe microanalysis (EPMA) analysis result for Fe-Ni in the film of the grain-oriented electrical steel sheet prepared in Example 5. As shown in FIG. 4 , it was confirmed that Ni:5%, Mg:40%, Si:20%, O:30%, Fe:5% were included in the film by weight%.
[124]
In the end, it can be confirmed that nickel hydroxide and cobalt hydroxide added in the annealing separator made a Fe-Ni composite together with magnesium oxide to improve magnetism compared to the conventional forsterite film.
[125]
The present invention is not limited to the embodiments, but may be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains may develop other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.
[126]
[Explanation of code]
[127]
100: grain-oriented electrical steel sheet 10: grain-oriented electrical steel sheet substrate
[128]
11: oxide layer 20: film
Claims
[Claim 1]
100 parts by weight of at least one of magnesium oxide and magnesium hydroxide; and 30 to 250 parts by weight of a metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide; Including, wherein the metal hydroxide has an average particle diameter of 0.01 to 80㎛ annealing separator composition for grain-oriented electrical steel sheet.
[Claim 2]
The annealing separator composition for a grain-oriented electrical steel sheet according to claim 1, wherein the metal hydroxide contains 30 to 250 parts by weight of the nickel hydroxide.
[Claim 3]
The annealing separator composition for grain-oriented electrical steel sheet according to claim 1, wherein the metal hydroxide comprises 30 to 150 parts by weight of the nickel hydroxide and 30 to 150 parts by weight of the cobalt hydroxide.
[Claim 4]
The annealing separator composition for grain-oriented electrical steel sheet according to claim 1, further comprising 1 to 10 parts by weight of ceramic powder.
[Claim 5]
The annealing separator composition for a grain-oriented electrical steel sheet according to claim 4, wherein the ceramic powder is at least one selected from Al 2 O 3 , SiO 2 , TiO 2 and ZrO 2 .
[Claim 6]
The annealing separator composition for grain-oriented electrical steel sheet according to claim 1, further comprising 50 to 500 parts by weight of a solvent.
[Claim 7]
A grain-oriented electrical steel sheet in which a film containing a composite of at least one of Fe-Ni, Fe-Co, or Fe-Ni-Co is formed on one or both sides of a grain-oriented electrical steel sheet substrate.
[Claim 8]
The grain-oriented electrical steel sheet according to claim 7, wherein, with respect to the cross section in the thickness direction of the steel sheet, the average particle diameter of at least one composite of Fe-Ni, Fe-Co, or Fe-Ni-Co is 1 to 100 nm.
[Claim 9]
According to claim 7, with respect to the cross section in the thickness direction of the steel sheet, the area occupied by the at least one composite of Fe-Ni, Fe-Co, or Fe-Ni-Co with respect to the coating area is 0.1 to 10% of the grain electric steel plate.
[Claim 10]
The method of claim 7, wherein the coating contains 0.1 to 40% by weight of at least one of Ni and Co, 40 to 85% by weight of Mg, 0.1 to 40% by weight of Si, 10 to 55% by weight of O, and Fe Grain-oriented electrical steel sheet included as a part.
[Claim 11]
The grain-oriented electrical steel sheet according to claim 7, wherein the film further comprises a Mg-Si composite.
[Claim 12]
The grain-oriented electrical steel sheet according to claim 7, wherein the film has a thickness of 0.1 to 10 μm.
[Claim 13]
The grain-oriented electrical steel sheet according to claim 7, wherein an oxide layer is formed from the interface between the coating film and the substrate to the interior of the substrate.
[Claim 14]
The grain-oriented electrical steel sheet according to claim 13, wherein the oxide layer comprises at least one composite of Fe-Ni, Fe-Co, or Fe-Ni-Co.
[Claim 15]
The method of claim 7, wherein the grain-oriented electrical steel sheet is silicon (Si): 2.0 to 7.0 wt%, aluminum (Al): 0.020 to 0.040 wt%, manganese (Mn): 0.01 to 0.20 wt%, phosphorus (P) 0.01 to 0.15% by weight, carbon (C) 0.01% by weight or less (excluding 0%), N: 0.005 to 0.05% by weight, and 0.01 to 0.15% by weight of antimony (Sb), tin (Sn), or a combination thereof And the balance is grain-oriented electrical steel sheet containing Fe and other unavoidable impurities.
[Claim 16]
preparing steel slabs; heating the steel slab; manufacturing a hot-rolled sheet by hot rolling the heated steel slab; manufacturing a cold-rolled sheet by cold-rolling the hot-rolled sheet; primary recrystallization annealing the cold-rolled sheet; applying an annealing separator on the surface of the steel sheet subjected to the primary recrystallization annealing; and performing secondary recrystallization annealing of the steel sheet coated with the annealing separator, wherein the annealing separator contains 100 parts by weight of at least one of magnesium oxide and magnesium hydroxide; and 30 to 250 parts by weight of a metal hydroxide including at least one of nickel hydroxide and cobalt hydroxide; Including, wherein the metal hydroxide has an average particle diameter of 0.01 to 80㎛ method of manufacturing a grain-oriented electrical steel sheet.
[Claim 17]
The method of claim 16 , wherein the primary recrystallization annealing of the cold-rolled sheet comprises decarburization annealing and nitridation annealing of the cold-rolled sheet at the same time or, after decarburization annealing, nitridation annealing.