KR102080165B1 - Annealing separating agent composition for grain oriented electrical steel sheet, grain oriented electrical steel sheet, and method for manufacturing the same - Google Patents

Abstract

The annealing separator composition for a grain-oriented electrical steel sheet according to an embodiment of the present invention contains 0.5 to 70 parts by weight of carbon, and 100 parts by weight of magnesium oxide or magnesium hydroxide in total.
In the grain-oriented electrical steel sheet according to the embodiment of the present invention, a coating layer is formed on one or both surfaces of the substrate of the grain-oriented electrical steel sheet, and the coating layer contains 0.5 to 70 wt% of C.

Description

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

An annealing separator composition for a grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet and a manufacturing method thereof. Specifically, the present invention relates to an annealing separator composition for grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet and a method of manufacturing the same, by adding carbon to improve the forsterite coating layer properties and magnetic properties.

Generally, a grain-oriented electrical steel sheet is an electrical steel sheet containing Si components in a steel sheet, having an aggregate structure in which the grain orientations are aligned in the {110} <001> direction, and having extremely excellent magnetic properties in the rolling direction. .

In general known oriented electrical steel sheet, the iron loss is improved by forming an insulating layer on a forsterite (Mg ₂ SiO ₄ ) -based base film and applying tensile stress to the steel sheet using the thermal expansion coefficient difference of the insulating layer. Although the noise reduction effect due to the magnetostriction is planned, there is a limit to satisfy the characteristic level in the high-quality oriented electrical steel sheet which is recently required.

In order to improve the forsterite coating layer characteristics in the conventional grain-oriented electrical steel sheet manufacturing process, a method of improving the surface characteristics of TiO ₂ powder on MgO has been proposed in the step of applying a fusion inhibitor containing MgO as a main component.

In addition, a method of removing the forsterite coating layer by applying alumina powder or colloidal silica and MgCl ₂ as a fusion inhibitor as a method of improving iron loss of a grain-oriented electrical steel sheet is known. However, the above method has a problem that the iron loss of the electrical steel sheet is rather inferior as the forsterite coating layer is removed, and there is a problem that it is difficult to form the insulating layer in a subsequent process.

An annealing separator composition for a grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet and a method of manufacturing the same. Specifically, by adding carbon, it is intended to provide an annealing separator composition for a grain-oriented electrical steel sheet, a grain-oriented electrical steel sheet and a manufacturing method thereof for improving the coating properties and magnetic properties.

The annealing separator composition for a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises 0.5 to 70 parts by weight of carbon, and 100 parts by weight of magnesium oxide or magnesium hydroxide in total.

Carbon may have an average particle diameter of 1 to 500 nm.

The carbon may be at least one selected from natural graphite, artificial graphite, carbon black, carbon fiber, graphene, and carbon on which the metal is supported.

The annealing separator composition for a grain-oriented electrical steel sheet according to an embodiment of the present invention may further comprise 1 to 10 parts by weight of ceramic powder.

The ceramic powder may be at least one selected from Al ₂ O ₃ , SiO ₂ , TiO _2, and ZrO ₂ .

Sb ₂ (SO ₄ ) ₃ , SrSO ₄ , BaSO ₄ or a combination thereof may further comprise 1 to 10 parts by weight.

In the grain-oriented electrical steel sheet according to the embodiment of the present invention, a coating layer is formed on one or both surfaces of the substrate of the grain-oriented electrical steel sheet, and the coating layer contains 0.5 to 70 wt% of C.

The coating layer contains carbide and forsterite.

With respect to 100% of the total area of the coating layer, the area of the carbide may be 0.5 to 50 area%.

Carbide may have an average particle diameter of 2 to 700 nm.

Carbide may include one or more of Fe carbide, Si carbide and Fe-Si composite carbide.

The coating layer further contains 3 to 80% by weight of Mg, 3 to 80% by weight of Si and 3 to 80% by weight of Fe.

The coating layer may have a thickness of 0.1 to 10 μm.

A ceramic layer may be further formed on the coating layer.

The base of the grain-oriented electrical steel sheet is 2.8 to 6.8 wt% of silicon (Si), 0.020 to 0.040 wt% of aluminum (Al), 0.01 to 0.20 wt% of manganese (Mn), antimony (Sb), tin (Sn), or these Combination of 0.01 to 0.15% by weight, and the balance may be composed of Fe and other unavoidable impurities.

Method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of manufacturing a cold rolled sheet; Primary recrystallization annealing of the cold rolled sheet; Applying an annealing separator on the surface of the primary recrystallized annealed steel sheet; And secondary recrystallization annealing of the steel sheet to which the annealing separator is applied.

The annealing separator comprises 0.5 to 70 parts by weight of carbon and 100 parts by weight of magnesium oxide and magnesium hydroxide in solids.

The step of manufacturing a cold rolled sheet may include manufacturing a steel slab; Heating the steel slab; Hot rolling the heated steel slab to produce a hot rolled sheet; And cold rolling the hot rolled sheet to prepare a cold rolled sheet.

The annealing separator according to an embodiment of the present invention may include a proper amount of carbon in the component, thereby removing defects in the coating layer, and improving the coating layer characteristics.

The annealing separator according to an embodiment of the present invention may include an appropriate amount of carbon in the component, thereby improving the magnetic properties of the whole grain-oriented electrical steel sheet including the coating layer.

1 is a schematic side cross-sectional view of a grain-oriented electrical steel sheet according to an embodiment of the present invention.
Figure 2 is a photograph of the grain-oriented electrical steel sheet prepared in Example 3.
3 is a photograph of a grain-oriented electrical steel sheet prepared in Comparative Example 1.
4 is a result of analyzing the coating layer of the grain-oriented electrical steel sheet prepared in Example 1.

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

The terminology used herein is for reference only to specific embodiments and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” include plural forms as well, unless the phrases clearly indicate the opposite. As used herein, the term "comprising" embodies a particular property, region, integer, step, operation, element, and / or component, and the presence of another property, region, integer, step, operation, element, and / or component, or It does not exclude the addition.

When a portion is referred to as "on" or "on" another portion, it may be directly on or on the other portion or may be accompanied by another portion therebetween. In contrast, when a part is mentioned as "directly above" another part, no other part is intervened in between.

Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Commonly defined terms used are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed contents, and are not interpreted as ideal or very formal meaning unless defined.

In addition, unless otherwise indicated,% means weight% and 1 ppm is 0.0001 weight%.

In an embodiment of the present invention, the meaning of further including an additional element means to include the balance by adding an additional amount of the additional element.

Hereinafter, exemplary embodiments of the present invention will be described in detail so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Annealing for oriented electrical steel sheets Separator

In one embodiment of the present invention, the annealing separator includes 0.5 to 70 parts by weight of carbon, and 100 parts by weight of magnesium oxide and magnesium hydroxide in total.

Carbon may reduce the whiteness of the forsterite coating to improve the surface quality of the coating layer 20. At the same time, carbon can improve the magnetism by forming a composite carbide during the high temperature annealing process. If the content of carbon is too low, the above effects may not be sufficiently exerted. If the carbon content is too high, the problem is that it excessively diffuses in the steel and degrades the magnetism. More specifically, carbon may be included in an amount of 0.5 to 50 parts by weight.

Carbon may be used in the form of carbon, wherein the average particle diameter may be 1 to 500nm. If the particle size is too small, black spots may occur when carbon aggregates with each other to form the coating layer 20. If the particle diameter is too large, a problem may occur that uniform application is difficult.

The kind of carbon is not particularly limited, and specifically, the carbon may be at least one selected from natural graphite, artificial graphite, carbon black, carbon fiber, graphene, and carbon on which metal is supported. The metal supported carbon may be at least one selected from Pd / C, Ru / C, Pt / C, Rd / C, Ni / C, Cu / C, Au / C, Ag / C, Co / C.

Magnesium oxide or magnesium hydroxide serves to supply Mg of monticelite. The magnesium oxide or magnesium hydroxide may be magnesium oxide (MgO). Since the magnesium oxide (MgO) is generally known widely, detailed description thereof will be omitted.

When water is included as the solvent of the slurry, the magnesium oxide is easily dissolved in water and may 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. Meaning of containing 100 parts by weight of magnesium oxide means containing 100 parts by weight of magnesium oxide when containing magnesium oxide alone, and including 100 parts by weight in total when magnesium oxide and magnesium hydroxide are included simultaneously. do.

The annealing separator composition for a grain-oriented electrical steel sheet may further comprise 1 to 10 parts by weight of ceramic powder. 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 formed coating layer 20 may be further improved.

Oriented electrical steel sheet annealing separator composition comprises _{Sb 2 (SO 4) 3,} SrSO 4, BaSO 4 , or may further comprise 1 to 10% by weight of the combination of the two. _{Sb 2 (SO 4) 3,} SrSO 4, BaSO 4 , or by an appropriate amount more combinations thereof, surface gloss can be excellent and the roughness produced very aesthetic oriented electrical steel sheet.

The annealing separator composition may further comprise a solvent for even dispersion and easy application of the solids. Water, alcohol, and the like may be used as the solvent, and may include 300 to 1000 parts by weight based on 100 parts by weight of magnesium oxide. As such, the annealing separator composition may be in the form of a slurry.

Oriented electrical steel sheet

In the grain-oriented electrical steel sheet 100 according to the embodiment of the present invention, the coating layer 20 is formed on one or both surfaces of the grain-oriented electrical steel sheet substrate 10. 1 is a schematic side cross-sectional view of a grain-oriented electrical steel sheet according to an embodiment of the present invention. 1 illustrates a case where the coating layer 20 is formed on the upper surface of the grain-oriented electrical steel sheet substrate 10.

The coating layer 20 includes C as compared to the conventional forsterite coating layer, and C reduces the whiteness of the forsterite coating to improve the surface characteristics of the coating layer 20. At the same time, C forms Fe-C, Si-C, and Fe-Si-C composite carbides, thereby giving the film tension due to the difference in coefficient of thermal expansion, thereby improving magnetic properties.

C in the coating layer 20 may include 0.5 to 70% by weight. If the content of C is too small, the above effects may not be sufficiently exerted. If the content of C is too high, if the content of carbon is too high, the problem is that it excessively diffuses in the steel and degrades the magnetism. More specifically, the carbon may be included in 0.5 to 50% by weight.

The coating layer 20 may contain 3 to 80% by weight of Mg. If the Mg content is too small, the amount of the coating layer 20 is insufficient, resulting in surface defects. If the Mg content is too high, a large amount of forsterite may be formed, resulting in inferior iron loss characteristics. Therefore, Mg may be included in the above range. Specifically, Mg may include 5 to 50% by weight. More specifically, it may include 7 to 15% by weight of Mg.

The coating layer 20 may contain 3 to 80% by weight of Si. If the Si content is too small, the amount of the coating layer 20 formed is insufficient, resulting in inferior adhesion. If the Si content is too high, surface defects of whitening may occur. Therefore, Si may be included in the above range. Specifically, it may include 5 to 50% by weight of Si. More specifically, it may include 7 to 15% by weight of Si.

The coating layer 20 may contain 3 to 80 wt% of oxygen (O). More specifically, it may include 5 to 50% by weight of O. More specifically, it may include 7 to 15% by weight of O.

The coating layer 20 may include Fe as a balance.

In general, in the manufacture of a grain-oriented electrical steel sheet, silicon (Si), which has the highest oxygen affinity in the steel sheet, reacts with oxygen in the first recrystallization annealing step, and SiO ₂ is formed on the surface of the steel sheet. In addition, when oxygen gradually penetrates into the steel sheet during annealing, iron (Fe) oxide (Fe ₂ SiO ₄ Etc.) are further formed. That is, in the first recrystallization annealing process, an oxide film containing the SiO ₂ and the iron (Fe) oxide is necessarily formed on the surface of the steel sheet.

After the first recrystallization annealing process, an annealing separator mainly containing magnesium oxide or magnesium hydroxide is applied to the surface of the steel sheet and then subjected to a second recrystallization annealing, wherein SiO ₂ in the oxide film is the magnesium oxide or magnesium hydroxide. React with This reaction may be represented by the following Chemical Scheme 1, or Chemical Formula 2, which corresponds to the reaction of forming forsterite (Mg ₂ SiO ₄ ), that is, a coating layer (primary coating, base coating). The coating layer formed by such Mg oxide or Mg hydroxide may help to make the secondary recrystallization stably occur during the secondary recrystallization annealing process.

2Mg (OH) ₂ + SiO ₂ → Mg ₂ SiO ₄ (Posterite) + 2H ₂ O

[Chemical Scheme 2] 2MgO + SiO ₂ → Mg ₂ SiO ₄ (Posterite) + 2H ₂ O

On the surface of the grain-oriented electrical steel sheet, except for special cases, it is common to form a coating layer mainly composed of forsterite. The coating layer usually has the effect of preventing fusion between the steel sheets wound with the coil, imparting tension due to the difference in thermal expansion with the steel sheet, and reducing iron loss and providing insulation.

In one embodiment of the present invention, in addition, by adding carbon to the annealing separator, it is possible to improve the film properties and magnetic properties by changing the properties of the coating layer 20 formed on the surface of the grain-oriented electrical steel sheet. Specifically, by adding C in addition to the forsterite, carbides are produced together in the coating layer. Since the produced forsterite and carbide have different thermal expansion properties, the effect of local shrinkage-expansion in the coating layer is different. Thus, it is possible to maximize the tension effect of the coating layer, thereby achieving a low iron loss of the steel sheet. In addition, carbides can stably participate in the coating layer forming reaction, and in addition to improving the properties of the coating layer, an additional magnetic improvement effect can be expected.

The carbide may be one or more of Fe carbide, Si carbide and Fe-Si composite carbide.

Such carbides may be present in an amount of 0.5 to 50 area%, relative to 100% of the total area of the coating layer. If too little carbide is formed, the above-described improvement effect cannot be expected. If too much carbide is formed, carbon may be carburized in steel to deteriorate magnetic properties. More specifically, the carbide may be present in an amount of 1 to 35 area% with respect to 100% of the total area of the coating layer.

Carbide may have an average particle diameter of 2 to 700 nm. If the particle size of the carbide is too small, the viscosity of the slurry may increase, which may cause a problem of poor solution stability. If the carbide grain size is too large, surface defects may occur. More specifically, the carbide may have an average particle diameter of 5 to 150 nm.

The coating layer 20 may have a thickness of 0.1 to 10 μm. If the thickness of the coating layer 20 is too thin, the film tension imparting ability may be lowered, which may cause a problem of iron loss. If the thickness of the coating layer 20 is too thick, the adhesion of the coating layer 20 may be inferior and peeling may occur. Therefore, the thickness of the coating layer 20 can be adjusted to the above-mentioned range. More specifically, the thickness of the coating layer 20 may be 0.8 to 6 ㎛.

In the grain-oriented electrical steel sheet 100 according to an embodiment of the present invention, a ceramic layer 30 may be further formed on the coating layer 20. 1 illustrates an example in which the ceramic layer 30 is further formed on the coating layer 20.

The thickness of the ceramic layer 30 may be 0.5 to 5 μm. If the thickness of the ceramic layer 30 is too thin, a problem may occur that the insulation effect of the ceramic layer 30 is less. If the thickness of the ceramic layer 30 is too thick, the adhesion of the ceramic layer 30 becomes low, and peeling may occur. Therefore, the thickness of the ceramic layer 30 can be adjusted in the above-described range. More specifically, the thickness of the ceramic layer 30 may be 0.8 to 3.2 μm.

Ceramic layer 30 may comprise ceramic powder. Ceramic powders are Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ io ₂ , Y ₂ O ₃ , 9Al ₂ O ₃ · 2B ₂ O ₃ , BN, CrN, BaTiO ₃ , SiC and TiC It may be one or more selected from. The particle diameter of the ceramic powder may be 2 to 900 nm. If the particle diameter of the ceramic powder is too small, the formation of the ceramic layer may be difficult. If the particle diameter of the ceramic powder is too large, the surface roughness may be roughened to cause surface defects. Therefore, the particle diameter of the ceramic powder can be adjusted to the above-mentioned range.

The ceramic powder may be in any one or more forms selected from the group including spherical, plate-shaped, and needle-shaped.

Ceramic layer 30 may further include metal phosphate. The metal phosphate may include one or more selected from Mg, Ca, Ba, Sr, Zn, Al, and Mn. When the metal phosphate is further included, the insulation of the ceramic layer 30 is further improved.

The metal phosphate may be composed of a compound by chemical reaction of metal hydroxide and phosphoric acid (H ₃ PO ₄ ).

The metal phosphate is composed of a compound by chemical reaction of metal hydroxide and phosphoric acid (H ₃ PO ₄ ), and the metal hydroxide is Ca (OH) ₂ , Al (OH) ₃ , Mg (OH) ₂ , B (OH) ₃ , Co (OH) ₂ and Cr (OH) ₃ It may be at least one or more selected from the group containing.

Specifically, the metal atom of the metal hydroxide is formed by forming a single bond, double bond, or triple bond by substitution reaction with phosphorus of phosphoric acid, the amount of unreacted free phosphoric acid (H ₃ PO ₄ ) is 25% by weight or less It may be made.

The metal phosphate is composed of a compound by chemical reaction of metal hydroxide and phosphoric acid (H ₃ PO ₄ ), and the weight ratio of the metal hydroxide to phosphoric acid may be represented by 1: 100 to 40: 100.

If too much metal hydroxide is included, the chemical reaction may not be completed and sediment may occur. If too little metal hydroxide is included, the corrosion resistance may be poor, so the range may be limited. have.

Hereinafter, the reason for limitation of the grain-oriented electrical steel sheet base material 10 component will be described.

Si: 2.8 to 6.8 wt%

Silicon (Si) increases the specific resistance of steel to reduce iron loss. If the Si content is too small, the specific resistance of steel becomes small, which leads to deterioration of iron loss characteristics and phase transformation at high temperature annealing, resulting in unstable secondary recrystallization. Problems may occur. If the content of Si is too large, brittleness may increase, which may make it difficult to cold roll. Therefore, the content of Si in the above range can be adjusted. More specifically Si may be included in the 3.8 to 5.8% by weight.

Al: 0.020 to 0.040 wt%

Aluminum (Al) is finally a nitride in the form of AlN, (Al, Si) N, (Al, Si, Mn) N and acts as an inhibitor. If the Al content is too small, it is difficult to expect a sufficient effect as an inhibitor. In addition, when the Al content is too much, the Al-based nitride is precipitated and grown too coarsely, and thus the effect as an inhibitor may be insufficient. Therefore, the content of Al in the above range can be adjusted.

Mn: 0.01 to 0.20 wt%

Manganese (Mn) has the effect of reducing the iron loss by increasing the specific resistance similar to Si, and reacts with nitrogen introduced by nitriding treatment with Si to form a precipitate of (Al, Si, Mn) N. It is an important element for suppressing growth of 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 the primary recrystallized grains, thereby destabilizing the secondary recrystallization. In addition, when the Mn content is too small, the austenite-forming element increases the austenite fraction during hot rolling reheating to increase the high capacity of the precipitates so that the primary recrystallization through refining the precipitate and MnS formation is not excessive. It can happen inadequately. Therefore, the content of Mn in the above range can be adjusted.

Sb, Sn or a combination thereof: 0.01 to 0.15% by weight

Sb or Sn is a grain boundary segregation element that prevents the movement of the grain boundary, so as a grain growth inhibitor, it promotes the generation of goth grains in the {110} <001> azimuth, so that secondary recrystallization is well developed. to be. If the content of Sb or Sn added alone or in combination is too small, problems may occur. If the content of Sb or Sn alone or in combination is too high, grain boundary segregation may occur severely, leading to brittleness of the steel sheet, which may cause plate breakage during rolling.

More specifically, it may include 0.01 to 0.05% by weight of Sb, 0.01 to 0.12% by weight of Sn.

C: 0.01 wt% or less

In the embodiment according to the present invention, C is a component that does not greatly help to improve the magnetic properties of the grain-oriented electrical steel sheet, so it is preferable to remove it if possible. However, if it contains more than a certain level, the rolling process promotes the austenite transformation of the steel to refine the hot rolled structure during hot rolling, thereby helping to form a uniform microstructure, so the C content in the slab is 0.03 weight It is preferably contained in more than%. However, when the C content is excessive, coarse carbides are formed and removal is difficult when decarburizing. Carbon is decarburized through a decarburization annealing process in the production of the grain-oriented electrical steel sheet, and C is included in an amount of 0.01 wt% or less in the grain-oriented electrical steel sheet to be manufactured.

N: 0.001 to 0.005 wt%

N is an element which reacts with Al or the like to refine the crystal grains. If these elements are properly distributed, as described above, it may be helpful to secure an appropriate primary recrystallization grain size by appropriately finely structured after cold rolling. However, if the content is excessive, the primary recrystallized grains are excessively refined, and as a result, the driving force causing grain growth during the secondary recrystallization may be increased due to the fine grains, thereby growing up to grains of undesirable orientation. In addition, excessive N content is not preferable because it takes a long time to remove in the final annealing process. Therefore, the upper limit of the nitrogen content is 0.005% by weight, and since the content of nitrogen to be dissolved in the slab reheating should be at least 0.001% by weight, the lower limit of the nitrogen content is preferably 0.001% by weight. Nitrogen is partially infiltrated through the immersion annealing process in the manufacturing of the grain-oriented electrical steel sheet, and nitrogen may be removed again during the second recrystallization annealing process. N is contained in 0.0001 ~ 0.05% by weight in the final grain-oriented electrical steel sheet.

Method for manufacturing oriented electrical steel sheet

Method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of manufacturing a cold rolled sheet; Primary recrystallization annealing of the cold rolled sheet; Applying an annealing separator on the surface of the primary recrystallized annealed steel sheet; And forming a coating layer on the surface of the steel sheet by secondary recrystallization annealing of the steel sheet coated with the annealing separator.

The step of manufacturing a cold rolled sheet may include manufacturing a steel slab; Heating the steel slab; Hot rolling the heated steel slab to produce a hot rolled sheet; And cold rolling the hot rolled sheet to prepare a cold rolled sheet.

Hereinafter, each step will be described in detail.

First, prepare a steel slab. The components of the steel slab have been described in detail with respect to the components of the grain-oriented electrical steel sheet described above, and thus repeated descriptions thereof will be omitted.

Next, the steel slabs are heated. At this time, the slab heating may be heated by a low temperature slab method at 1,200 ℃ or less.

Next, the heated steel slab is hot rolled to prepare a hot rolled sheet. After the hot rolled sheet is manufactured, the prepared hot rolled sheet may be hot rolled.

Next, the hot rolled sheet is cold rolled to produce a cold rolled sheet. Cold rolling may be performed once, or two or more cold rolling including intermediate annealing may be performed.

Next, the cold rolled sheet is subjected to primary recrystallization annealing. At this time, decarburization and nitriding can be carried out. At this time, the cold rolled sheet may be simultaneously decarburized and nitrided, after decarburized, nitrided, or after nitrified and decarburized.

Next, an annealing separator is applied on the surface of the steel sheet subjected to primary recrystallization annealing. Since the annealing separator is specifically described above, repeated descriptions are omitted.

Next, the secondary recrystallization annealing of the steel sheet coated with the annealing separator. In the process of secondary recrystallization annealing, C and Mg in the annealing separator and Si in the grain-oriented electrical steel sheet substrate 10 react to form the coating 20.

In the second recrystallization annealing, the primary cracking temperature was 700 ° C and the secondary cracking temperature was 1200 ° C. The temperature can be controlled at 15 ° C / hr in the temperature range. In addition, the gas atmosphere may be a mixed gas atmosphere of 25% nitrogen and 75% hydrogen up to 1200 ° C., and after the temperature reaches 1200 ° C., the gas atmosphere may be maintained for 15 hours in a 100% hydrogen atmosphere and then furnace cooled.

After the second recrystallization annealing, the method may further include forming the ceramic layer 30. Since the ceramic layer 30 has also been described above in detail, repeated description thereof will be omitted. As a method of forming the ceramic layer 30, the ceramic powder may be sprayed onto the coating 20 to form the ceramic layer. Specifically, plasma spray coating, plasma spray coating, high velocity oxy fuel, aerosol deposition, or cold spray coating may be applied. More specifically, it is possible to use a plasma spray coating method of forming a ceramic layer by supplying ceramic powder to a heat source in which a gas containing Ar, H ₂ , N ₂ , or He is plasma-ized at an output of 20 to 300 kW. In addition, the plasma spray coating method, the ceramic layer 30 by supplying a gas containing Ar, H ₂ , N ₂ , or He in the form of a mixture suspension of a ceramic powder and a solvent to a plasma sourced heat source at an output of 20 to 300 kW Can be formed. At this time, the solvent may be water or alcohol.

In addition, as a method of forming the ceramic layer 30, a method of forming a ceramic layer by applying a ceramic layer forming composition containing ceramic powder and metal phosphate can be used.

After the ceramic layer 30 is formed, magnetic domain refinement may be performed as necessary.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.

Experimental Example

3.4 wt% silicon (Si), 0.03 wt% aluminum (Al), 0.05 wt% manganese (Mn), 0.04 wt% antimony (Sb), 0.11 wt% tin (Sn), 0.06 wt% carbon (C) Wt%, 40 wt% nitrogen (N), and the balance was prepared with a slab consisting of Fe and other unavoidable impurities.

The slab was heated at 1150 ° C. for 220 minutes and then hot rolled to a thickness of 2.3 mm to prepare a hot rolled sheet.

The hot rolled plate was heated to 1120 ° C., held at 920 ° C. for 95 seconds, quenched with water, pickled, and cold rolled to a thickness of 0.23 mm to prepare a cold rolled plate.

The cold rolled sheet was placed in a furnace maintained at 850 ° C., and then dew point temperature and oxidation performance were adjusted, and decarburization and primary recrystallization annealing were carried out simultaneously in a hydrogen, nitrogen, and ammonia mixed gas atmosphere, thereby carrying out decarburization annealing. A prepared steel sheet.

As an annealing separator composition, distilled water was mixed in the form of a slurry three times with the solid components summarized in Table 1 below, and the slurry was applied to a decarburized, annealed steel sheet using a roll, followed by secondary recrystallization annealing.

In the second recrystallization annealing, the primary crack temperature was 700 ° C., the secondary crack temperature was 1200 ° C., and the temperature range was 15 ° C./hr. Further, up to 1200 ° C., a mixed gas atmosphere of 50% by volume of nitrogen and 50% by volume of hydrogen was maintained. After reaching 1200 ° C., the mixture was kept in a 100% by volume hydrogen gas atmosphere for 20 hours and then subjected to furnace cooling.

Subsequently, TiO ₂ was supplied as a ceramic powder to a heat source in which argon (Ar) gas was converted into plasma at an output of 250 kW, thereby forming a ceramic layer having a thickness of 0.9 μm on the surface of the final annealing plate.

The grain-oriented electrical steel sheets prepared in Examples and Comparative Examples were evaluated under magnetic conditions and noise characteristics at 1.7T and 50 Hz, and the results are shown in Table 2 below.

Magnetic properties of electrical steel sheets are evaluated using W17 / 50 and B8. W17 / 50 refers to the power loss seen by magnetizing a magnetic field with a frequency of 50 Hz up to 1.7 Tesla. Here, Tesla is a unit of magnetic flux density, which means flux per unit area. B8 represents the magnetic flux density value flowing in the electrical steel sheet when a current amount of 800 A / m flows through the winding wound around the electrical steel sheet.

In addition, the insulation properties were measured by coating the Franklin meter according to ASTM A717 International Standard.

In addition, the adhesion is shown by the minimum arc diameter without film peeling when the specimen is bent 180 ° in contact with a 10 to 100 mm arc.

In addition, surface defects were classified as good when white spots and tissue exposed surface defects were found, and when defects and surface defects were not found.

division
Annealed Separator Composition (parts by weight) Carbon class
(Weight part / average particle diameter) MgO Ceramic powder
(Al ₂ O ₃ ) Sb ₂ (SO ₄ ) ₃ Example 1 Graphite (5 parts by weight / 100nm) 100 3 10 Example 2 Graphene (10 parts by weight / 150nm) 100 5 5 Example 3 Graphite (20 parts by weight / 20nm) 100 7 5 Example 4 Pd / C (30 parts by weight / 50 nm) 100 5 5  Example 5 Graphite (70 parts by weight / 100nm) 100 4 One Comparative Example 1 - 100 6 5 Comparative Example 2 Graphite (0.1 parts by weight / 100nm) 100 5 7 Comparative Example 3 Graphite (75 parts by weight / 100nm) 100 7 7

Iron loss (W17 / 50) Magnetic flux density (B8) Insulation (mA) Adhesiveness (mmφ) Surface properties Example 1 0.82 1.920 150 20 Good Example 2 0.76 1.927 145 20 Good Example 3 0.72 1.930 75 20 Good Example 4 0.75 1.924 57 20 Good Example 5 0.78 1.915 55 20 Good Comparative Example 1 0.971 1.908 450 25 Bad Comparative Example 2 0.970 1.908 452 25 Bad Comparative Example 3 1.051 1.885 370 30 Bad

As shown in Table 1 and Table 2, when an appropriate ratio of carbon is added to the annealing separator, it can be confirmed that the magnetic properties and insulation properties are improved, and the surface properties are good. On the other hand, Comparative Examples 1 and 2, in which no carbon was added or too little, were inferior to the Examples, and the surface properties were poor. Moreover, iron loss was inferior in the comparative example 3 which added excessive carbon.

In addition, photographs of the coating layers of the grain-oriented electrical steel sheets prepared in Example 3 and Comparative Example 1 are shown in FIGS. 2 and 3, respectively. 2 and 3, it can be seen that the grain-oriented electrical steel sheet according to one embodiment of the present invention has good surface characteristics.

In addition, the result of analyzing the coating layer component of the grain-oriented electrical steel sheet manufactured in Example 3 is shown in FIG. As shown in Figure 4, it can be seen that the C, Mg components are mainly included.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person of ordinary skill in the art to which the present invention pertains does not change the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

100: oriented electrical steel sheet, 10: holding steel sheet,
20: film layer 30: ceramic layer

Claims (17)

Annealing separator composition for a grain-oriented electrical steel sheet comprising 0.5 to 70 parts by weight of carbon and 100 parts by weight of magnesium oxide and magnesium hydroxide in total. The method of claim 1,
The carbon is an annealing separator composition for grain-oriented electrical steel sheet having an average particle diameter of 1 to 500nm. The method of claim 1,
The carbon is an annealing separator composition for a grain-oriented electrical steel sheet of at least one selected from natural graphite, artificial graphite, carbon black, carbon fiber, graphene and carbon supported metal. The method of claim 1,
Annealing separator composition for grain-oriented electrical steel sheet further comprising 1 to 10 parts by weight of ceramic powder. The method of claim 4, wherein
The ceramic powder is an annealing separator composition for a grain-oriented electrical steel sheet of at least one selected from Al ₂ O ₃ , SiO ₂ , TiO ₂ and ZrO ₂ . The method of claim 1,
_{Sb 2 (SO 4) 3,} SrSO 4, BaSO 4 , or 1 to 10 parts by weight of a combination of grain-oriented electrical steel sheet portion further comprises annealing separator composition. The coating layer is formed on one or both sides of the grain-oriented electrical steel sheet, the coating layer comprises 0.5 to 70% by weight of C, the coating layer comprises a carbide and forsterite. delete The method of claim 7, wherein
The grain-oriented electrical steel sheet having an area of 0.5 to 50 area% of carbide with respect to 100% of the total area of the coating layer. The method of claim 7, wherein
The carbide is a grain-oriented electrical steel sheet having an average particle diameter of 2 to 700nm. The method of claim 7, wherein
The carbide is a grain-oriented electrical steel sheet comprising at least one of Fe carbide, Si carbide and Fe-Si composite carbide. The method of claim 7, wherein
The coating layer is a grain-oriented electrical steel sheet further comprises 3 to 80% by weight of Mg, 3 to 80% by weight of Si and 3 to 80% by weight of O and the balance. The method of claim 7, wherein
The coating layer is a grain-oriented electrical steel sheet having a thickness of 0.1 to 10 ㎛. The method of claim 7, wherein
The grain-oriented electrical steel sheet further comprising a ceramic layer on the coating layer. The method of claim 7, wherein
The oriented electrical steel sheet substrate is silicon (Si): 2.8 to 6.8% by weight, aluminum (Al): 0.020 to 0.040% by weight, manganese (Mn): 0.01 to 0.20% by weight, antimony (Sb), tin (Sn), or It comprises 0.01 to 0.15% by weight of a combination thereof, the balance is a grain-oriented electrical steel sheet consisting of Fe and other unavoidable impurities. Manufacturing a cold rolled plate;
Primary recrystallization annealing of the cold rolled sheet;
Applying an annealing separator on the surface of the first recrystallized annealing steel sheet; And
A second recrystallization annealing of the steel sheet coated with the annealing separator,
The annealing separator is a method for producing a grain-oriented electrical steel sheet containing 0.5 to 70 parts by weight of carbon, and 100 parts by weight of magnesium oxide and magnesium hydroxide in total. The method of claim 16,
Manufacturing the cold rolled plate
Manufacturing a steel slab;
Heating the steel slab;
Hot rolling the heated steel slab to produce a hot rolled sheet; And
Cold rolling the hot rolled sheet, a method for producing a grain-oriented electrical steel sheet comprising the step of manufacturing a cold rolled sheet.

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