JP2001032055A - Grain oriented silicon steel sheet excellent in iron loss characteristic, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively improve the quality of film and to provide excellent iron loss characteristic by impregnating metal particles and/or ceramic particles into the voids in a forsterite film formed on a finish annealed silicon steel sheet and also into the vicinity of the interface between the film and ferrite. SOLUTION: Ionized metal particles (Ti, etc.), and/or ceramic particles (SiNx, etc.), are poured into a finish annealed grain oriented silicon steel sheet having forsterite film while applying tensile stress of about (0.01 to 10) kgf/mm2 over the longitudinal direction of the steel sheet. By this procedure, the fine particles can be impregnated to about 0.01-0.5 μm thickness into the voids in the forsterite film on the whole surface of the steel sheet and into the interface between the film and ferrite. As an effective method for impregnation, e.g. a method, where the fine particles of nitride, carbide, or oxide ceramics prepared by allowing metal which is melted or melted and ionized in vacuum to react using reactive nitrogen, carbon, or oxygen gas in the vicinity of a substrate are used, can be cited, and an HCD method and a magnetron sputtering method can effectively be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In recent years, remarkable development efforts for satisfying the ultimate demand for reducing iron loss in improving the electrical and magnetic properties of a grain-oriented silicon steel sheet have been gradually gaining fruit. is there. The present invention relates to a grain-oriented silicon steel sheet having excellent iron loss properties and a method for producing the same, and more particularly to effectively improve a forsterite-based coating to further improve iron loss properties. .

[0002]

2. Description of the Related Art As is well known, a grain-oriented silicon steel sheet is a product in which secondary recrystallized grains of a product are highly integrated in the (110) [001], that is, Goss orientation, and are mainly used for cores of transformers and other electric appliances. it is used as, as the electric and magnetic properties is high (as represented by ₈ value B) magnetic flux density of the product, iron loss (W represented by _17/50) is low, and further excellent in magnetostriction property Is required.

[0003] The unidirectional silicon steel sheet is manufactured through a variety of complicated processes. However, many improvements have been made to this manufacturing method.
Thickness: 0.30 mm product on the magnetic flux density B ₈ or more 1.90T, the iron loss W _17/50 is 1.05 W / kg or less, thickness: 0.23 mm product on the magnetic flux density B ₈ or more 1.89T the iron loss Ultra low iron loss unidirectional silicon steel sheets having W _17/50 of 0.80 W / kg or less have been produced.

[0004] Generally, a unidirectional silicon steel sheet is annealed mainly composed of an iron oxide called firelite (FeSiO ₄ ) and MgO formed on the steel sheet surface during decarburization and primary recrystallization annealing before secondary recrystallization. Applying tension to the steel sheet surface by a forsterite-based coating generated by a high-temperature reaction at the time of finish annealing with a separating agent, and an insulating coating mainly composed of phosphate and colloidal silica formed thereon As a result, iron loss has been reduced and magnetostriction has been improved.

On the other hand, recently, after removing a forsterite-based coating formed during finish annealing of a silicon steel sheet,
There has been proposed a method of improving iron loss characteristics by polishing the surface of a steel sheet and thereafter further applying a ceramic coating by CVD or PVD (for example, Japanese Patent Publication No. 63-54767).
No.). Also, various methods have been proposed for directly achieving mirror finishing without forming a forsterite-based coating during finish annealing.

[0006] All of the above techniques are mainly metallurgical techniques, but apart from these methods, as proposed in Japanese Patent Publication No. 57-2252, the surface of the steel sheet after the finish annealing is applied. Laser irradiation and plasma irradiation (B.Fukuda, K.Sato,
T.Sugiyama, A.Honda and Y.Ito: Proc. Of ASM Con.
of Hard and Soft Magnetic Materials.8710-008, (US
A), (1987)), and a method (magnetic domain segmentation technology) was developed to reduce iron loss by artificially reducing the magnetic domain width by 180 °. With the development of this technology, the iron loss of a grain-oriented silicon steel sheet has been greatly reduced. However, this technique has a disadvantage that it cannot withstand annealing at high temperatures, and has a problem that its application is limited to a laminated iron core transformer that does not require strain relief annealing.

In this regard, as a domain refining technique capable of withstanding strain relief annealing, a linear groove is introduced into the surface of a unidirectional silicon steel sheet after finish annealing, and the demagnetizing effect of the groove is applied to form a magnetic domain. The method of subdivision was industrialized (H. Kobayashi,
E.Sasaki, M.Iwasaki and N.Takahashi: Proc.SMM −
8., (1987), P.402). Separately, a method has been developed in which a final cold-rolled sheet of unidirectional silicon steel sheet is subjected to local electrolytic etching to form grooves and subdivide magnetic domains (Japanese Patent Publication No. 8-6140). , Has been industrialized.

[0008] As described above, recent iron loss improvement techniques include:
In metallurgy, it is common to mirror-finish or smooth the steel sheet surface after finish annealing.However, to make the steel sheet mirror-like or smooth, remove the formed forsterite-based coating or In addition, various measures are required to prevent the formation of a forsterite-based film, and a large load is inevitable both in terms of process and cost. In this regard, if the forsterite-based coating formed at the time of finish annealing can be effectively used as it is and magnetic properties comparable to those of a mirror-finished material can be obtained, the effect is immeasurable.

[0009]

SUMMARY OF THE INVENTION The present invention satisfies the above-mentioned demands advantageously, and is a unidirectional silicon steel sheet having improved iron loss characteristics by effectively improving the film quality of a forsterite-based coating. With its advantageous manufacturing method.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, found that fine metal particles or ceramic particles were deposited on the surface of a silicon steel sheet provided with a forsterite coating. Injecting and filling the gaps in the forsterite-based coating and the vicinity of the interface with the ground iron with such fine particles introduces new tensile strain near the interface with the forsterite-based coating, resulting in iron loss characteristics. Was found to be significantly improved. The present invention is based on the above findings.

That is, the gist of the present invention is as follows. 1. A finish-annealed unidirectional silicon steel sheet having a forsterite-based coating, wherein metal particles and / or ceramic particles are impregnated in gaps of the forsterite-based coating and in the vicinity of an interface with ground iron. -Oriented silicon steel sheet with excellent iron loss characteristics.

2. Iron loss characteristics characterized by impregnating ionized metal particles and / or ceramic particles over the entire surface of a finish-annealed unidirectional silicon steel sheet having a forsterite-based coating under a tensile state extending in the longitudinal direction. An excellent method for producing unidirectional silicon steel sheets.

3. 2. The method for producing a unidirectional silicon steel sheet having excellent iron loss characteristics according to the above item 2, wherein a tensile stress applied to the steel sheet is 0.01 to 10 kgf / mm ² .

In the above manufacturing method, in order to efficiently impregnate fine metal particles and ceramic particles ionized in the gap between the forsterite and the interface with the ground iron, a voltage is applied to the ground steel plate to implant ions. It is desirable to increase the amount.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The results of experiments which have led to the completion of the present invention will be described below. C: 0.076 wt%, Si: 3.38 wt%, Mn: 0.071 wt%, Se:
0.020 wt%, Sb: 0.025 wt%, Al: 0.020 wt%, N: 0.
A continuous cast slab of silicon steel containing 0078 wt% and Mo: 0.012 wt%, with the balance being substantially Fe, was heated at 1350 ° C. for 4 hours, and then hot-rolled to give a sheet thickness of 2.2 mm. Rolled,
Then, it is subjected to hot-rolled sheet annealing at 1050 ° C for 1.5 minutes (also referred to as homogenizing annealing), and then cold-rolled twice with intermediate annealing at 1000 ° C to produce a final cold-rolled sheet with a sheet thickness of 0.23 mm. did.

Then, on the surface of the cold-rolled sheet, an etching resist ink containing an alkyd resin as a main component is subjected to gravure offset printing so that the non-applied portion has a width of 200 μm at a right angle to the rolling direction and a spacing of 4 mm. The coating was applied so as to remain in a linear shape, and baked at 200 ° C. for 3 minutes. At this time, the resist thickness was 2 μm. The steel plate coated with the etching resist in this manner was subjected to electrolytic etching to form a linear groove having a width of 200 μm and a depth of 20 μm, and then immersed in an organic solvent to remove the resist.
At this time, the electrolytic etching is performed in a NaCl electrolyte at a current density of:
The test was performed under the conditions of 10 A / dm ² and a processing time of 20 seconds.

Then, after decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., an annealing separator containing MgO as a main component is applied to the surface of the steel sheet by slurry, and then at 850 ° C. for 15 hours. After annealing, the temperature was raised from 850 ° C to 1150 ° C at a rate of 10 ° C / h to develop secondary recrystallized grains strongly integrated in Goss orientation.
Purification was performed in dry H ₂ at 1200 ° C.

Thereafter, after removing unreacted MgO, 3 vol
Activated forsterite film (film thickness: 1.2 μm) by immersion treatment in 60% phosphoric acid solution (60 ° C, 45 seconds), and then applying a tensile stress of 2 kgf / mm ² to the longitudinal direction of the steel sheet Then, Ti (HCD method) and SiN _X (magnetron sputtering method) were injected and impregnated on the entire surface of the film using a PVD apparatus.
Thereafter, a coating solution containing phosphate and colloidal silica was applied and baked to form an insulating film. FIG. 1 shows the result of examining the relationship between the iron loss characteristics of the grain-oriented silicon steel sheet thus obtained and the impregnation amounts of Ti and SiN _{X in} the forsterite film.

It is difficult to directly measure the amount of Ti and SiN _X impregnated in the forsterite film. However, the impregnation amount is proportional to the amount of the fine particles deposited on the smooth surface, that is, the film thickness. Therefore,
In the present invention, the film thickness measured using another sample which is a silicon steel plate smoothed by chemical polishing (this film thickness was measured using an Alpha-step 200 (using a Tencor instrument Co., Ltd.)) Ti and S in forsterite coating
The impregnation amount of iN _X was a substitute display. In particular, when impregnating SiN _X by magnetron sputtering,
Using a device as shown in FIG. 2, an experiment was performed by applying a voltage of −50 V to a silicon steel substrate.

As is clear from FIG. 1, the iron loss was significantly reduced by impregnating the forsterite film with Ti and SiN _X having a thickness of 0.01 to 0.5 μm as a substitute for the film thickness.

Although the reason why the iron loss property is improved by impregnating fine metal particles or ceramic particles in the forsterite film as described above has not been clearly elucidated yet, the inventors have found that. I think as follows. That is, the schematic diagram shown in FIG. 3 (a) shows a situation in which an insulating film is applied on a forsterite film of a current silicon steel sheet, and the insulating film is applied on the irregularities of the forsterite. Since the tension is applied in the situation, it is not possible to say that the silicon steel sheet exerts a sufficient tension effect. On the other hand, according to FIG. 3 (b), which schematically illustrates the present invention, the fine particles of Ti or SiN _X are impregnated in the gaps of the forsterite coating and in the vicinity of the interface with the ground iron, so that the silicon steel sheet It is considered that a tensile strain is newly generated at the interface of and the applied tension to the steel plate increases by that amount, so that iron loss is reduced. Here, the fine particles impregnate the gaps in the forsterite film and the vicinity of the interface with the ground iron to produce the above-described effect, but may be attached to the surface of the forsterite film.

As described above, according to the present invention, tension can be effectively applied to the vicinity of the interface of the silicon steel sheet, so that a high magnetic flux density and a low iron loss can be obtained. Furthermore, in the present invention, a small amount of Ti or S
Since the iN _X need only impregnation is a technique which can be extremely effectively reduce iron loss at a low cost. In this case, since Ti and Si are fine particles of several tens of ionized Ti ⁺ and Si ⁺ , the gaps in the forsterite film can be easily impregnated.

Next, preferred materials and manufacturing conditions in the present invention will be described. As the silicon-containing steel which is the material of the present invention, any of the conventionally known component systems is suitable, and the typical compositions are as follows. C: 0.01 to 0.08 wt% If C is less than 0.01 wt%, the suppression of hot rolled texture is insufficient, and large elongated grains are formed, thereby deteriorating magnetic properties. Since it takes a long time to decarburize in the charcoal process and is not economical, it is preferable to set the content to about 0.01 to 0.08 wt%.

Si: 2.0 to 4.0 wt% If Si is less than 2.0 wt%, sufficient electric resistance cannot be obtained, so that eddy current loss increases and iron loss deteriorates.
If the content is more than wt%, brittle cracks are likely to occur during cold rolling, so it is preferable to be in the range of about 2.0 to 4.0 wt%.

Mn: 0.01 to 0.2 wt% Mn is an important component that determines the amount of MnS or MnSe as a dispersed precipitation phase which affects secondary recrystallization of a unidirectional silicon steel sheet. If the Mn content is less than 0.01% by weight, the absolute amount of MnS or the like necessary for causing secondary recrystallization becomes insufficient, causing incomplete secondary recrystallization and increasing surface defects called blisters. On the other hand, if it exceeds 0.2 wt%, even if dissociated solid solution of MnS or the like is performed in slab heating or the like, the dispersed precipitate phase precipitated during hot rolling tends to be coarse, and the optimal size distribution desired as an inhibitor is impaired. Therefore, the Mn content is preferably set to about 0.01 to 0.2 wt%.

S: 0.008 to 0.1 wt%, Se: 0.003 to 0.1 wt% Both S and Se are 0.1 wt% or less, especially S is 0.00
The content of Se is preferably in the range of 8 to 0.1 wt%, and the content of Se is preferably in the range of 0.003 to 0.1 wt%. The reason is that if these contents exceed 0.1 wt%, the hot and cold workability deteriorates, and if they do not reach the lower limits, respectively, there is no particular effect on the primary grain growth suppressing function as MnS and MnSe. It is. In addition, complex addition of Al, Sb, Cu, Sn, B, etc., which are conventionally known as inhibitors, does not hinder the effects of the present invention.

Next, the manufacturing process of the grain-oriented silicon steel sheet according to the present invention will be described. First, to melt the material,
An LD converter, an electric furnace, an open hearth furnace, and other known steelmaking furnaces can be used, as well as vacuum melting and RH degassing.

According to the present invention, S, Se contained in the raw material
Alternatively, as a method of adding a small amount of another primary grain growth inhibitor to molten steel, any conventionally known method may be used. For example, LD converter, at the end of RH degassing or during molten steel at the time of ingot casting Can be added. In the slab production, the continuous casting method is advantageous in terms of cost reduction, economical and technical advantages such as uniformity of components or quality in the longitudinal direction of the slab. It does not prevent use.

The continuously cast slab is heated to a temperature of 1300 ° C. or more in order to dissociate and form a solid solution of the inhibitor in the slab. Thereafter, the slab is subjected to hot rough rolling and then hot finish rolling to form a hot-rolled sheet having a thickness of usually about 1.3 to 3.3 mm.

Next, the hot-rolled sheet is subjected to hot-rolled sheet annealing in a temperature range of about 850 to 1100 ° C. if necessary, and then cold-rolled once or twice with intermediate annealing to obtain a final sheet thickness. However, in order to obtain a product having high magnetic flux density and low iron loss, it is necessary to pay attention to the final cold rolling reduction (usually 55 to 90%).
The sheet thickness is not particularly limited, and any sheet of this kind having a normal thickness of 0.1 to 0.5 mm is advantageously applicable.

When a linear groove for magnetic domain subdivision is formed on the surface of a steel sheet, it is particularly advantageous to perform the processing on a steel sheet which has been subjected to the final cold rolling to a product sheet thickness. That is, on the surface of the final cold-rolled sheet or the steel sheet before and after the secondary recrystallization,
At a distance of 2 to 10 mm in the direction crossing the rolling direction, width: 50 to
A linear concave region having a depth of 500 μm and a depth of 0.1 to 50 μm is formed. Here, the interval between the linear concave regions is limited to the range of 2 to 10 mm. If it is less than 2 mm, the unevenness of the steel plate is too advisable, the magnetic flux density is lowered, and it is not economical.
This is because if it exceeds 10 mm, the effect of magnetic domain refining becomes small. If the width of the concave region is less than 50 μm, it is difficult to use the demagnetizing field effect.On the other hand, if it exceeds 500 μm, the magnetic flux density decreases and it is not economical.
A range of 50 to 500 μm is preferred. Furthermore, if the depth of the concave region is less than 0.1 μm, the demagnetizing field effect cannot be effectively used.On the other hand, if it exceeds 50 μm, the magnetic flux density decreases and it is not economical. A range of 0.1 to 50 μm is preferred. The direction in which the linear concave regions are formed is optimally in a direction perpendicular to the rolling direction, that is, in the amplitude direction, but substantially the same effect can be obtained as long as it is within ± 30 ° with respect to the amplitude direction.

Further, as a method of forming the linear concave region,
On the surface of the final cold-rolled sheet, an etching resist is applied by printing, after baking, an etching process is performed, and then the method of removing the resist is compared with a method using a conventional knife edge or a laser, It is advantageous in that it can be carried out industrially stably and that iron loss can be more effectively reduced by tension.

Hereinafter, a typical example of the above-described linear groove forming technique by etching will be specifically described. An etching resist ink containing an alkyd resin as a main component is gravure offset printed on the surface of the final cold-rolled sheet so that the non-applied portion remains linearly at a right angle to the rolling direction at a width of 200 μm and a spacing of 4 mm in a linear manner. After applying, bake at 200 ° C for about 20 seconds. At this time, the resist thickness is about 2 μm.
The steel plate coated with the etching resist in this way,
By performing electrolytic etching or chemical etching, a linear groove having a width of 200 μm and a depth of 20 μm is formed.
Next, the resist is removed by immersion in an organic solvent. The electrolytic etching conditions at this time are as follows:
10 A / dm ² , treatment time: about 20 seconds, and chemical etching conditions: immersion time in HNO ₃ solution: about 10 seconds.

Next, the steel sheet is subjected to decarburization annealing. This annealing makes the cold rolled structure the primary recrystallized structure,
In the final annealing (also called finish annealing), (110) [0
C] which is harmful when secondary recrystallized grains of [01] orientation are developed
For example, in wet hydrogen at 750 to 880 ° C.

The final annealing is performed to sufficiently develop secondary recrystallized grains having a (110) [001] orientation.
Usually, it is carried out by immediately raising the temperature to 1000 ° C. or higher by box annealing and maintaining the temperature. This final annealing is performed by applying an annealing separator such as magnesia, and a forsterite-based coating is simultaneously formed on the surface of the steel sheet. In this final annealing, in order to develop a secondary recrystallized structure highly integrated in the (110) [001] orientation, it is more advantageous to conduct a constant annealing at a low temperature of 820 ° C. to 900 ° C. For example, slow annealing at a heating rate of about 0.5 to 15 ° C./h may be used.

According to the present invention, ionized metal particles and / or ceramic particles are injected into a unidirectional silicon steel sheet having a forsterite-based coating manufactured as described above under a tensile state in the longitudinal direction. ,
Fine metal or ceramic particles are impregnated into the gap between the forsterite coating on the entire surface of the steel sheet and the boundary with the ground iron. As a method of impregnating fine metal and ceramic particles into the gaps of the forsterite film, any method may be used, but the simplest and most effective method is to dissolve or dissolve / ionize in vacuum. A nitride obtained by reacting a metal near the substrate using reactive nitrogen, carbon, and oxygen gas,
There is a method using fine particles of carbide or oxide ceramic. As the PVD method in this case, H having a high ionization rate is used.
It is more effective to use the CD method or the magnetron sputtering method.

In the above impregnation, the tensile stress applied to the steel sheet is preferably about 0.01 to 10 kgf / mm ² . This is because the tensile stress applied to the steel sheet is 0.01
If it is less than kgf / mm ² , a sufficient amount of fine particles cannot be impregnated, while if it exceeds 10 kgf / mm ² , the magnetic flux density deteriorates due to plastic deformation. More preferred range is 0.05~5 kgf / mm ^2.

The amount of fine metal and ceramic particles to be impregnated into the gaps of the forsterite film is extremely small, but is effective in reducing iron loss. As shown in FIG. It may be about 0.01 to 0.5 μm.
In addition, even if the impregnation amount is further increased, the effect of reducing the iron loss is not completely lost, but the impregnation treatment of the ionized metal particles and / or ceramic particles increases the cost and is not economical.

Next, the silicon steel sheet is coated with a coating solution for a tension insulating film containing phosphate and colloidal silica as main components in accordance with a conventional method on the surface of the silicon steel sheet.
Bake at 500-1000 ° C to make a tensile insulation film (film thickness: 0.5
５5 μm). Here, as a coating solution for a tension insulating film mainly composed of phosphate and colloidal silica, for example, as disclosed in Japanese Patent Publication No. 53-28375, colloidal silica: 4 to 16 wt%, aluminum phosphate : 3 to 24% by weight, chromic anhydride and / or chromate: 0.2 to 4.5% by weight, and colloidal silica as disclosed in JP-B-56-52117: 7 to 24% by weight. , Magnesium phosphate: 5-30wt%
(However, the molar ratio of magnesium phosphate to colloidal silica: 20/80 to 30/70), and if necessary, chromic anhydride, chromate and / or dichromate: 0.01
Coating liquids with ５5 wt% are advantageously suitable.

[0040]

[Example] C: 0.075 wt%, Si: 3.33 wt%, Mn: 0.072
wt%, Se: 0.020 wt%, Sb: 0.025 wt%, Al: 0.020 wt
%, N: 0.0073% by weight and Mo: 0.012% by weight, with the balance being 1330.
After heat treatment at 3 ℃ for 3 hours, hot rolling: 2.2mm thickness
Hot-rolled sheet, and then subjected to uniform annealing at 1050 ° C., and then cold-rolled twice with intermediate annealing at 1000 ° C.
Finished into a final cold-rolled sheet of 23 mm thickness. Then, on the surface of this cold-rolled sheet, an etching resist ink containing an alkyd resin as a main component is gravure offset printed, and the non-applied portion remains linearly at a right angle to the rolling direction with a width of 200 μm and an interval of 4 mm in a linear manner. After baking, it was baked at 200 ° C. for about 20 seconds. At this time, the resist thickness was 2 μm. The steel plate coated with the etching resist in this way is subjected to electrolytic etching to obtain a width of 200 μm and a depth of 20 μm.
Was formed and then immersed in an organic solvent to remove the resist. The electrolytic etching at this time was performed in a NaCl electrolytic solution under the conditions of a current density of 10 A / dm ² and a processing time of 20 seconds.

Then, after decarburization and primary recrystallization annealing in wet H ₂ at 840 ° C., an annealing separator containing MgO as a main component was applied to the surface of the steel sheet by slurry, and then at 850 ° C. for 15 hours. after annealing, after it developed a secondary recrystallized grains accumulated strongly Goss orientation was heated to 1180 ° C. at a rate of 10 ° C. / h from 850 ° C., facilities a purification treatment in dry of H ₂ 1220 ° C. did.

The silicon steel sheet provided with a forsterite film thus obtained was pickled in a 2 vol% phosphoric acid solution (60 ° C., 45 seconds) to activate the forsterite film (film thickness: 0.1 μm). In a state where a tensile stress of 3 kgf / mm ² was applied to the longitudinal direction of the sample, the following metal and / or ceramic particles were impregnated using a magnetron sputtering method. (1) SiN _X : 0.12 μm as a substitute for film thickness. (2) Cr: 0.08 μm in the film thickness alternative display. (3) Cr + TiN: (0.05 + 0.03) μm instead of film thickness. Thereafter, a coating solution containing phosphate and colloidal silica was applied and baked to form an insulating film.

Table 1 shows the results obtained by examining the magnetic properties of each product plate thus obtained. In addition, the table also shows, for comparison, the results of a survey on a conventional material that is not treated as described above.

[0044]

[Table 1]

As is clear from the table, according to the present invention,
When fine ceramic particles and metal particles are impregnated on the entire surface of the forsterite coating of a silicon steel sheet, a small amount of effective iron loss reduction is achieved.

[0046]

As described above, according to the present invention, a unidirectional silicon steel sheet having much better magnetic properties than conventional materials can be obtained by effectively utilizing the forsterite-based coating formed at the time of finish annealing. It can be obtained stably.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between iron loss of a grain-oriented silicon steel sheet and the impregnation amounts of Ti and SiN _{X in} a forsterite film.

FIG. 2 is a schematic diagram of a magnetron sputtering apparatus suitable for use in carrying out the present invention.

FIG. 3 shows a state in which an insulating film is applied on a forsterite film of a current silicon steel sheet (a) and Ti or SiN is formed in a gap in the forsterite film and a boundary with a ground iron according to the present invention.
FIG. 4 is a diagram showing a comparison (b) of a state in which fine particles such as _X are impregnated and then an insulating film is applied.

Claims (3)

[Claims] 1. A finish-annealed unidirectional silicon steel sheet having a forsterite-based coating, wherein metal particles and / or ceramic particles are impregnated in gaps in the forsterite-based coating and in the vicinity of an interface with ground iron. A unidirectional silicon steel sheet having excellent iron loss characteristics. 2. The method according to claim 1, wherein the surface of the finish-annealed unidirectional silicon steel sheet having the forsterite-based coating is impregnated with ionized metal particles and / or ceramic particles under a tensile state in the longitudinal direction. For producing a unidirectional silicon steel sheet having excellent iron loss characteristics. 3. The method for producing a unidirectional silicon steel sheet according to claim 2, wherein the tensile stress applied to the steel sheet is 0.01 to 10 kgf / mm ² and has excellent iron loss characteristics.