WO2016089076A1

WO2016089076A1 - High silicon steel plate having excellent magnetic property and manufacturing method thereof

Info

Publication number: WO2016089076A1
Application number: PCT/KR2015/012963
Authority: WO
Inventors: 홍병득; 김동균
Original assignee: 주식회사 포스코
Priority date: 2014-12-05
Filing date: 2015-12-01
Publication date: 2016-06-09
Also published as: JP2018504518A; JP6523458B2; CN107002208B; KR101633611B1; KR20160068563A; CN107002208A

Abstract

A high silicon steel plate having an excellent magnetic property and a manufacturing method thereof are provided. According to the present invention, the method for manufacturing a high silicon steel plate comprises: a strip casting step for performing strip casting on a molten silicon steel under a nitrogen or argon atmosphere, the molten silicon steel consisting of 4 to 7 wt% of Si, 0.1 to 3 wt% of Al, and 5.5 to 7.5 wt% of the sum of Si and Al, the remainder being Fe; a hot rolling step for performing hot rolling on the strip-cast strip to manufacture a high silicon steel plate; a heat treatment step for performing heat treatment on the hot-rolled high silicon steel plate in a non-oxidizing mixed atmosphere of nitrogen and argon or hydrogen and nitrogen; a warm rolling step for performing warm rolling on the heat-treated high silicon steel plate to a final thickness of 0.5 mm or less; and a final heat treatment step for performing final heat treatment on the high silicon steel plate at a temperature of 800°C to 1200°C, wherein the method further comprises the step for forming a soft ferrite layer on the surface of the high silicon steel plate, which is manufactured to the final thickness, in order to improve a magnetic property in a high frequency region after performing the final heat treatment step.

Description

High silicon steel sheet with excellent magnetic properties and its manufacturing method

The present invention relates to a high silicon electrical steel sheet having excellent magnetic properties and a method of manufacturing the same, and more particularly, to form a composite structure by applying magnetic iron oxide before or after the final heat treatment to form a composite structure, The present invention relates to a high silicon steel sheet and a method of manufacturing the same, which have dramatically improved their properties.

In general, silicon-containing electrical steel sheets are used as iron core materials for transformers, electric motors, generators, and other electronic devices. Electrical steel sheets are required to have excellent magnetic flux density and iron loss. The larger the magnetic flux density is, the smaller the amount of iron cores are required to achieve the same performance, so that the electric apparatus can be miniaturized, and the smaller the iron loss, the smaller the energy loss.

Iron loss causing energy loss consists of eddy current loss and hysteresis loss. As the frequency increases in AC, the components of eddy current loss become larger. The eddy current loss is generated by the eddy current generated when the magnetic field is induced in the iron core, so silicon is added to reduce the eddy current loss. When the silicon content is added up to 6.5%, the magnetostriction causing noise is reduced to zero, and the permeability is maximized. When the silicon content is 6.5%, the high frequency characteristic is very good. By using the excellent magnetic properties of such high-silicon steel, it can be applied to the use of high value-added electrical equipment such as inverters and reactors for new renewable energy generators, generator induction heaters for gas turbines, and reactors for uninterruptible power supplies.

High-silicon steel sheet containing 6.5% Si is excellent in magnetic properties, but if the Si is more than 3.5%, cold rolling is impossible by the usual method. Therefore, since it is impossible to manufacture high silicon steel sheets by ordinary hot rolling-cold or hot rolling, it has been attempted to manufacture high silicon steel sheets having excellent magnetic properties by other methods.

The technologies known to produce high silicon steel sheet are the direct casting method using single roll or double roll such as Japanese Patent Laid-Open No. 56-3625, and the high silicon steel is placed inside the outside, such as Japanese Patent Laid-Open No. 5-171281. The so-called clad method of rolling with low silicon steel in an attempt has been attempted, but these techniques have not been commercialized yet.

Korean Patent Publication No. 10-0374292 et al. Uses powder metallurgy to make high silicon steel blocks made of powder instead of high silicon steel sheets and use them as substitutes for high silicon steel sheets. Pure iron powder core, high silicon steel powder core, and sand dust powder core are used in combination, but the soft magnetic properties are inferior to that of high silicon steel sheet due to the characteristics of the powder.

As a technique for mass-producing high silicon steel sheets containing 6.5% Si, the Japan Special Office No. 38-26263, which is diffusion-annealed using SiCl4 on a 3% Si steel sheet by chemical vapor deposition (CVD) There are small 45-21181 and Japanese Patent Laid-Open No. 62-227078. This method has the disadvantage of using toxic SiCl 4 and requiring a long time for diffusion annealing.

It is known that it is impossible to cold roll a silicon steel sheet containing more than 3.5% Si because the brittleness of the silicon steel sheet increases as the silicon content increases in the electrical steel sheet. However, attempts have been made to produce thin sheets in a laboratory by a so-called warm rolling method of raising the rolling temperature.

Increasing the rolling temperature has the effect of improving the rolling property, but the improvement effect is not sufficient as it, there are many difficulties in the process of manufacturing hot rolled plate.

An object of the present invention is to provide a high silicon steel sheet having excellent magnetic properties and a method of manufacturing the same, by forming a MnZnNi-based soft ferrite layer having excellent high frequency characteristics on a surface of a high silicon steel sheet, thereby dramatically improving the magnetic properties of the high frequency region.

According to one embodiment of the present invention, a silicon steel molten metal composed of Si 4-7%, Al 0.1-3%, Si + Al sum of 5.5-7.5% by weight, and the remaining Fe is strip-casted under nitrogen or argon atmosphere. A strip casting step, a hot rolling step of hot rolling the strip cast strip to produce a high silicon steel sheet, and heat treatment of the hot rolled high silicon steel sheet in a non-oxidizing atmosphere of nitrogen, argon, or a mixed atmosphere of hydrogen and nitrogen. A high silicon steel sheet including a heat treatment step, a warm rolling step of warm rolling the heat treated high silicon steel sheet to a final thickness of 0.5 mm or less, and a final heat treatment step of finally heat treating the high silicon steel sheet at a temperature of 800 ° C. to 1200 ° C. In the manufacturing method of

After performing the final heat treatment step, in order to improve the magnetic properties of the high frequency region is provided a method of manufacturing a high silicon steel sheet having excellent magnetic properties comprising the step of forming a soft ferrite layer on the surface of the high silicon steel sheet manufactured to a final thickness Can be.

The soft ferrite layer may be formed on both sides of the surface of the high silicon steel sheet produced to the final thickness.

The soft ferrite layer may be made of MnZnNi-based soft ferrite.

The MnZnNi-based soft ferrite may be made of Mn oxide, Zn oxide, Ni oxide, Fe oxide.

The sum of the thicknesses of both surfaces of the soft ferrite layer may be 1 μm or more and 30 μm or less.

The soft ferrite layer forming step is a step of applying a soft ferrite powder mixed with an electrical steel coating liquid on the surface of the high silicon steel sheet,

And applying the soft ferrite powder mixed with a phosphate binder to the surface of the high-grade steel sheet, and then mixing and applying the electrical steel coating liquid onto the soft ferrite powder, and

The soft ferrite powder may be made of any one of the steps of adhering to the surface of the steel plate at high speed in a vacuum or at room temperature.

At least one of SiO ₂ , CaO, Nb ₂ O ₅ , V ₂ O ₅ , ZrO ₂ , and MoO ₃ may be added to the soft ferrite layer.

According to one embodiment of the present invention, a high silicon steel sheet having excellent magnetic properties may be provided, wherein a soft ferrite layer is formed on the surface of the high silicon steel sheet manufactured to a final thickness in order to improve the magnetism of the high frequency region. have.

The soft ferrite layer may be made of MnZnNi-based soft ferrite.

The soft ferrite layer is a layer formed by applying a soft ferrite powder to the surface of the high silicon steel sheet by mixing with an electrical steel coating liquid, the soft ferrite powder is mixed with a phosphate-based binder on the surface of the high silicon steel sheet and then applied to the soft ferrite powder The layer formed by mixing and applying the coating on the electrical steel sheet, and the soft ferrite powder may be any one of the layers formed on the surface by colliding the steel sheet at high speed in a vacuum or at room temperature.

According to this embodiment, it is possible to produce a high silicon steel sheet with a significant improvement in the magnetic properties of the high frequency region by forming a MnZnNi-based soft ferrite layer having excellent high frequency characteristics on the surface of the high silicon steel sheet.

1 is a block diagram of a method of manufacturing a high silicon steel sheet having excellent magnetic properties according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art can easily understand, the embodiments described below may be modified in various forms without departing from the concept and scope of the present invention. Where possible, the same or similar parts are represented using the same reference numerals in the drawings.

The terminology used below is merely to refer to specific embodiments, 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 phrases clearly indicate the opposite. As used herein, the meaning of “comprising” embodies a particular characteristic, region, integer, step, operation, element and / or component, and other specific characteristics, region, integer, step, operation, element, component and / or group. It does not exclude the presence or addition of.

All terms including technical terms and scientific terms used below have the same meaning as those commonly understood by those skilled in the art. Terms defined in advance are additionally interpreted to have a meaning consistent with the related technical literature and the presently disclosed contents, and are not interpreted in an ideal or very formal sense unless defined.

The inventors of the present invention invented a method of manufacturing a high silicon steel sheet which combines strip casting with a warm rolling method and replaces Al with 6.5% Si to provide excellent workability and excellent magnetic properties. This excellent soft ferrite powder layer was formed to develop a composite structure to develop a high silicon steel sheet that greatly improved magnetic properties.

Soft ferrite is a compound having a spinel-type crystal structure, and the magnetic property of the material is easily changed depending on the direction and the magnitude of the magnetic field. Usually, Fe2O3 iron oxide accounts for 60 to 70% by weight and is classified into manganese zinc ferrite, nickel zinc ferrite, magnesium zinc ferrite, and the like according to the remaining metal oxide components. Hard ferrite, compared to soft ferrite, is a material that does not easily change its magnetic properties depending on the direction and magnitude of the magnetic field. It is also commonly referred to as a permanent magnet. Fe2O3 iron oxide accounts for about 90% by weight and its use is divided according to the metal components added to improve other properties.

In general, soft ferrite powder has high magnetic permeability, saturation magnetic flux density, low magnetic degradation at high temperature, and excellent magnetic stability. In particular, MnZnNi ferrite has high saturation flux density, magnetic permeability and low loss magnetic properties in the relatively wide frequency range of 100KHz ~ 500KHz. Ferrite is used to make the core shape in the form of sintered powder.

In the present invention, by the method of forming these soft ferrites on the surface of the high silicon electrical steel sheet was able to significantly improve the magnetic properties of the existing high silicon steel sheet. The high frequency characteristics of high silicon steel sheet have excellent magnetism in the frequency range of several hundred Hz to several KHz. It has been found that forming a powder soft ferrite layer having excellent ultra-high frequency characteristics on the surface of such a high silicon steel sheet has more excellent characteristics.

When the steel sheet is used as a core, energy loss mainly occurs in the surface layer. By forming a soft ferrite layer having excellent high frequency characteristics on the surface, it is possible to greatly improve iron loss.

Hereinafter, a high silicon steel sheet having excellent magnetic properties according to an embodiment of the present invention will be described.

High silicon electrical steel sheet having excellent magnetic properties, particularly high magnetic properties in the high frequency region, according to an embodiment of the present invention, stripcasting, hot rolling, annealing heat treatment steel containing a large amount of Si and Al of more than 5.5% After making the final thickness by combining warm rolling, etc., the MnZnNi-based soft ferrite layer is formed on the surface.

Specifically, the high silicon steel sheet, by weight ratio of 4 to 7% of Si, 0.1 to 3% of Al, 5.5 to 7.5% of the sum of Si + Al and strip cast silicon steel molten metal consisting of the remaining Fe under nitrogen or argon atmosphere After hot-rolling the strip cast strip to produce a high silicon steel sheet, the hot-rolled high silicon steel sheet is heat-treated in a non-oxidizing atmosphere of nitrogen, argon or a mixed atmosphere of hydrogen and nitrogen, and then has a final thickness of 0.5 mm or less. After warm rolling to a thickness, the high silicon steel sheet is finally heat treated at a temperature of 800 ℃ ~ 1200 ℃,

In order to improve the magnetism of the high frequency region, a soft ferrite layer may be formed on the surface of the high silicon steel sheet manufactured to a final thickness.

A method of manufacturing a high silicon steel sheet having excellent magnetic properties according to an embodiment of the present invention will be described.

Method for producing a high silicon steel sheet having excellent magnetic properties according to an embodiment of the present invention, Si 4 ~ 7%, Al 0.1 ~ 3%, Si + Al sum of 5.5 ~ 7.5% by weight ratio consisting of the remaining Fe Strip casting step of strip casting silicon steel molten metal under nitrogen or argon atmosphere (S10),

Hot rolling step (S20) of manufacturing the high silicon steel sheet by hot rolling the strip cast strip,

Next, the heat treatment step (S30) of heat-treating the hot-rolled high silicon steel sheet in a non-oxidizing atmosphere of nitrogen, argon or a mixed atmosphere of hydrogen and nitrogen,

Thereafter, in order to avoid the formation of regular phases, it is quenched at a cooling rate of 30 ° C./sec or more to 100 ° C., followed by warm rolling including at least one heat treatment of 900 to 1200 ° C., and the warm rolling temperature is 300 ° C. or more. Warm rolling step to make the high silicon steel sheet to a final thickness of 0.5mm or less (S40),

Thereafter, the high silicon steel sheet comprises a final heat treatment step (S50) for performing a final heat treatment at a temperature of 800 ~ 1200 ℃,

After performing the final heat treatment step (S50), in order to improve the magnetic properties of the high frequency region includes the step of forming a soft ferrite layer on the surface of the high silicon steel sheet manufactured to the final thickness (S60).

The manufacturing method of the high silicon steel sheet which applies the method of forming a soft ferrite layer in the surface layer of the said high silicon steel sheet does not need to be limited to the method which combined strip casting and warm rolling. The present invention is applicable not only to quench solidification by strip casting, but also to processes that can be produced through steelmaking-continuous casting-hot rolling. However, in methods other than strip casting, there is a possibility that productivity is extremely deteriorated due to crack generation during rolling. Furthermore, it is also applicable to the high silicon steel plate manufactured by the method of Japanese Unexamined-Japanese-Patent No. 38-26263 which makes high silicon steel by the CVD method using SiCl4 gas.

In the method for producing a high silicon steel sheet of the present invention, the lower the C content and the N content, the better the rollability and the better the magnetic properties.

If the Si content is 4% or less, the magnetism is not good. If the Si content is 7% or more, the machining is impossible.

If the Al content is less than 0.1%, there is no effect of improving the rollability, and if it is more than 3%, the rollability is not good. If Si + Al is less than 5.5%, the high frequency characteristics are not good, and if it is more than 7.5%, processing is impossible.

It is preferable to hot roll immediately after strip casting, rather than to hot roll immediately after casting by strip casting, since it can reduce the load of warm rolling. In addition, there is an advantage that does not need to heat the strip separately if the hot rolling directly connected to the strip casting manufacturing apparatus. It is most preferable to hot roll the strip immediately after casting, but it is also preferable to cool the strip and then to treat it in a separate line rather than to hot roll directly without hot rolling. Hot rolling not only reduces the load of the hot rolling, but also hot rolling to break the casting structure to make the grains finer, which is helpful for the subsequent hot rolling.

It is desirable to heat treat the hot rolled plate rather than just hot roll it. Heat treatment prior to hot rolling eliminates the stresses generated during hot rolling, heat treatment in the region of A2 irregular phases, and then quenching to suppress formation of B2 and DO3 regular phases, resulting in better ductility.

The hot rolling temperature was investigated and found to be 300 ° C as the critical temperature. It appeared that there was little ductility when it became 300 degrees C or less, and extending | stretching is possible at 300 degreeC or more. At least 350 ° C is preferred for mass production.

The high temperature steel sheet, which is made thin by the final thickness of 0.5mm or less by the final rolling, is finally heat treated to improve magnetism. If the heat treatment temperature is 800 ° C. or less, the grain growth is insufficient and the iron loss is bad. If the heat treatment temperature is 1200 ° C or higher, it is not preferable in terms of economics and productivity, and even if a non-oxidation component crisis is used, the surface oxide layer is easily formed, which impedes the movement of the magnetic domains, thereby damaging magnetism.

MnZnNi-based soft ferrite consisting of manganese oxide, zinc oxide, nickel oxide and Fe-based oxide is applied to the surface of the high silicon steel made to the final thickness. The soft ferrite powder may be applied by mixing with a conventional electrical steel coating liquid, or the soft ferrite powder may be applied by mixing with a phosphate binder and then coated with a conventional electrical steel coating liquid on the soft ferrite powder.

The thickness of the soft ferrite layer made of soft ferrite powder is 1 µm or more. If the thickness is 1 탆 or less, there is no effect of forming a composite structure. If the thickness of the soft ferrite layer is 30 μm or more, when punching the steel sheet, there is a disadvantage in that the surface layer is broken, so the upper limit of the thickness is 30 μm.

The demand for high-frequency electrical steel sheets used as iron core materials for high-frequency equipment is on the rise. It is widely used in motors used in computers, dental power tools, motors of electric vehicles, reactors, transformers for renewable energy, and generators. The frequency range in which a high frequency electrical steel sheet is in charge is in the range of tens to hundreds of Hz, and the area in which high silicon steel is in charge is hundreds of Hz to several KHz. On the other hand, powder sintered core using soft ferrite has been used above several tens of KHz.

The present inventors continued their research with the idea that forming a soft ferrite layer on the surface of high silicon steel would not only improve the magnetism of the high frequency region in charge of the high silicon steel, but also expand the usable frequency range. When a soft ferrite layer of 1 µm or more was formed on the surface of the silicon steel, the magnetism of the high silicon steel was greatly reduced. The soft ferrite layer is applied to both surfaces of the sheet-like high silicon steel sheet surface. The sum of the thicknesses of the soft ferrite layers coated on both surfaces of the surface of the high silicon steel sheet should be 1 µm or more. However, when the sum of both sides of the thickness of the soft ferrite layer exceeds 30 µm, when the steel sheet is punched in the form of a core, the surface layer is crumbly and it is found that there is a difficulty in maintaining the surface layer.

As a method of forming the soft ferrite layer, a method of mixing soft ferrite powder into a general electrical steel coating liquid and applying it, or mixing the soft ferrite powder with a phosphate or polymer and applying it to a high silicon steel sheet in a liquid state, and then a general electrical steel coating liquid And a method of applying the soft ferrite powder to a steel plate at high speed in a vacuum or at room temperature at high speed, and the like.

The configuration of the soft ferrite layer is composed of so-called MnZnNi-based soft ferrite composed of manganese oxide, zinc oxide, nickel oxide and iron oxide. SiO ₂ , CaO, Nb ₂ O ₅ , V ₂ O ₅ , ZrO ₂ , MoO _{3 in} the soft ferrite At least one or more may be added. These oxides have excellent magnetic properties in the high frequency region, and can greatly improve the magnetism of the high silicon steel in the surface layer of the high silicon steel sheet.

In order to produce a soft ferrite core by sintering, the shape of the sintered body is different for each core, there is a disadvantage that a high temperature and high pressure heat treatment is required for core manufacturing. However, in the present invention, by simply applying a soft ferrite on the surface of the thin silicon steel sheet thickness, there is an advantage that can be manufactured by punching out as much as required size to manufacture the core.

Example 1

High silicon steel alloys of 5.5% Si and 1.0% Al, by weight, were cast to a thickness of 2.0 mm using a vertical twin roll stripcaster. A 2.0 mm thick strip was hot rolled to 1.0 mm using a hot rolling mill connected to the strip caster. The hot rolling start temperature is 1050 ° C.

The hot rolled high silicon steel sheet was heated at 1000 ° C. for 5 minutes in an atmosphere of 20% hydrogen and 80% nitrogen, and then quenched to room temperature at a cooling rate of 200 ° C./sec.

Thereafter, the solution was pickled with hydrochloric acid to remove the surface oxide layer. After the heat-treated high silicon steel sheet was lowered to 0.1 mm at a temperature of 400 ° C., and then annealed at 1000 ° C. for 10 minutes at 1000 ° C. for 10 minutes in a dry atmosphere of 20% hydrogen, 80% nitrogen, and dew point below -10 ° C. The MnZnNi soft ferrite was applied to the surface layer, the insulation coating was again applied on the application layer, and then cured to measure magnetic properties. Coating thickness is the combined value of the upper and lower surfaces of a steel plate. The composition and magnetism of the soft ferrite are shown in Table 1.

B50 (T), which measured the magnetic properties shown in Table 1, measured the magnetic flux density, and the higher the magnetic flux density was, the better the magnetic property was. In addition, W10 / 400 and W10 / 1000 are measured the iron loss of the commercial frequency, the lower the iron loss is evaluated as having a lower magnetic.

Here, B50 (T) is the magnetic flux density value when the magnetic field strength is 5000 amp (amps) / m in Telsa unit, and W10 / 400 (W / Kg) is the frequency when the magnetic flux density value is 1.0 Telsa. Is the loss value when 400Hz, W10 / 1000 (W / Kg) is the loss value when the frequency is 1000Hz when the magnetic flux density value is 1.0 Telsa.

If the coating thickness of the soft ferrite layer is less than 1 μm, the high frequency iron loss characteristics are poor and there is no soft ferrite coating effect. If the coating thickness of the soft ferrite layer is 30um or more, the peeling phenomenon of the soft ferrite layer of the surface layer occurs, the surface roughness is not uniform, there is a disadvantage that the drop rate when laminated with the core.

[Revision under Rule 26 08.12.2015]

Claims

A strip casting step of strip casting a silicon steel molten metal composed of Si 4-7%, Al 0.1-3%, Si + Al sum of 5.5-7.5% by weight, and the remaining Fe in a nitrogen or argon atmosphere; A hot rolling step of producing a high silicon steel sheet by hot rolling the strip, a heat treatment step of heat-treating the hot rolled high silicon steel sheet in a non-oxidizing atmosphere of nitrogen, argon or a mixed atmosphere of hydrogen and nitrogen, and the heat-treated high silicon In the method of manufacturing a high silicon steel sheet comprising a warm rolling step of warm rolling the steel sheet to a final thickness of 0.5mm or less, and a final heat treatment step of the final heat treatment of the high silicon steel sheet at a temperature of 800 ℃ ~ 1200 ℃,

After performing the final heat treatment step, forming a soft ferrite layer on the surface of the high silicon steel sheet manufactured to the final thickness in order to improve the magnetism of the high frequency region

Method for producing a high silicon steel sheet having excellent magnetic properties, including.
The method of claim 1,

The soft ferrite layer is a method of producing a high silicon steel sheet having excellent magnetic properties, characterized in that formed on both sides of the surface of the high silicon steel sheet produced to a final thickness.
The method of claim 2,

The soft ferrite layer is a method for producing a high silicon steel sheet having excellent magnetic properties, characterized in that the MnZnNi-based soft ferrite.
The method of claim 3,

The MnZnNi-based soft ferrite is a method of manufacturing a high silicon steel sheet having excellent magnetic properties, characterized in that consisting of Mn oxide, Zn oxide, Ni oxide, Fe oxide.
The method of claim 2,

The sum of the thicknesses of both surfaces of the soft ferrite layer is 1 µm or more and 30 µm or less.
The method according to any one of claims 1 to 5,

The soft ferrite layer forming step is a step of applying a soft ferrite powder mixed with an electrical steel coating liquid on the surface of the high silicon steel sheet,

And applying the soft ferrite powder mixed with a phosphate binder to the surface of the high-grade steel sheet, and then mixing and applying the electrical steel coating liquid onto the soft ferrite powder, and

A method for producing a high silicon steel sheet having excellent magnetic properties, characterized in that the soft ferrite powder is subjected to any one of the steps of colliding the steel sheet at high speed in a vacuum or at room temperature and pasting it onto the surface.
The method of claim 6,

SiO 2 , CaO, Nb 2 O 5 , V 2 O 5 , ZrO 2 , MoO 3 The method of manufacturing a high silicon steel sheet having excellent magnetic properties, characterized in that the soft ferrite layer is added.
The molten silicon steel is strip cast in a nitrogen or argon atmosphere, and the strip cast strip is hot rolled to produce a high silicon steel sheet, and the hot rolled high silicon steel sheet is scattered in a mixed atmosphere of nitrogen, argon or hydrogen and nitrogen. In the high silicon steel sheet manufactured by heat-treating in a chemical atmosphere and warm rolling to the final thickness, the final high heat treatment of the high silicon steel sheet,

High silicon steel sheet having excellent magnetic properties, characterized in that the soft ferrite layer is formed on the surface of the high silicon steel sheet manufactured to the final thickness in order to improve the magnetism of the high frequency region.
The method of claim 8,

The soft ferrite layer is a high silicon steel sheet having excellent magnetic properties, characterized in that formed on both sides of the surface of the high silicon steel sheet manufactured to a final thickness.
The method of claim 9,

The soft ferrite layer is a high silicon steel sheet having excellent magnetic properties, characterized in that consisting of MnZnNi-based soft ferrite.
The method of claim 10,

The MnZnNi-based soft ferrite is a high silicon steel sheet having excellent magnetic properties, characterized in that consisting of Mn oxide, Zn oxide, Ni oxide, Fe oxide.
The method of claim 9,

The high silicon steel sheet having excellent magnetic properties, characterized in that the sum of the thicknesses of both surfaces of the soft ferrite layer is 1 µm or more and 30 µm or less.
The method according to any one of claims 9 to 12,

The soft ferrite layer is a layer formed by applying a soft ferrite powder to the surface of the high silicon steel sheet by mixing with an electrical steel coating liquid, the soft ferrite powder is mixed with a phosphate-based binder on the surface of the high silicon steel sheet and then applied to the soft ferrite powder High-silicon steel sheet having excellent magnetic properties, characterized in that the layer formed by mixing and applying the coating coating on the electrical steel sheet, and the layer formed by colliding the soft ferrite powder to the steel sheet at a high speed at a vacuum or room temperature at high speed. .
The method of claim 13,

A high silicon steel sheet having excellent magnetic properties, characterized in that at least one of SiO 2 , CaO, Nb 2 O 5 , V 2 O 5 , ZrO 2 , and MoO 3 is added to the soft ferrite layer.