JP2001200377A - Method for producing superlow core loss grain oriented silicon steel sheet and dry plating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deposit a ceramic tensile film on the surface of a grain oriented silicon steel sheet at a high speed without deteriorating the film quality and adhesion. SOLUTION: The surface of a grain oriented silicon steel sheet subjected to finish annealing is deposited with an Si-N-O-C series ceramic film containing at least one kind selected from Fe, Al and Ti by using a magnetron sputtering method at least as for an initial layer, and, next, the surface of the ceramic film is deposited with the same kind of or a different kind of ceramic tensile film by an electron beam method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ultra-low iron loss unidirectional silicon steel sheet and a dry plating apparatus, and more particularly to a finish-annealed silicon steel sheet having a surface or a linear concave region which has been subjected to finish annealing. Improve productivity by applying a ceramic tension coating on the surface of a silicon steel sheet to improve iron loss characteristics without reducing the effect of applying tension by the ceramic coating, effectively increasing the deposition rate. At the same time, an attempt is made to advantageously reduce manufacturing costs.

[0002]

BACKGROUND ART grain oriented silicon steel sheet is mainly being used as transformer cores and other electrical equipment, (represented by ₈ value B) flux density as the magnetization characteristic is high, the iron loss (W
_17/50 ) is required to be low.

[0003] In order to improve the magnetic properties of a unidirectional silicon steel sheet, it is necessary to first align the <001> axis of secondary recrystallized grains in the steel sheet with the rolling direction, and secondly, to make the final It is necessary to minimize impurities and precipitates remaining in the product.

[0004] For this reason, since NPGoss proposed a basic manufacturing technique by two-stage cold rolling of a grain-oriented silicon steel sheet, a number of improvements have been made to the technique, and the magnetic flux density and the density of the grain-oriented silicon steel sheet have been improved. Iron loss values have improved over the years. Among them, the most typical ones are Sb and MnSe or
JP-B-51-13469 using MnS as an inhibitor, and JP-B-33-4710 and JP-B-40-156 using AlN and MnS as inhibitors.
The method according to 44 JP and Sho 46-23820 Patent Publication, according to these methods B ₈ is now the product is obtained having a high magnetic flux density exceeding 1.88T.

In order to obtain a product having a higher magnetic flux density, Japanese Patent Publication No. 577-14737 discloses a method in which Mo is added to a material in a complex manner.
In Japanese Patent Publication No. 62-42968, Mo is added to the material in a complex manner, and then the quenching treatment is applied after intermediate annealing immediately before the final cold rolling, so that B ₈ has a high magnetic flux density of 1.90 T or more. And iron loss W _17/50 is 1.05 W / kg (product thickness: 0.30m
m) It is disclosed that the following low iron loss can be obtained, but there is still room for improvement in reducing iron loss.

[0006] In particular, the demand for reducing power loss as much as possible after the energy crisis of more than ten years ago has been remarkably increased, and accordingly, further improvements in the use of iron core materials are desired. Therefore, in order to minimize eddy current loss, the product thickness was reduced.
Many of those having a thickness of 23 mm (9 mil) or less have come to be used.

[0007] All of the above-mentioned techniques are mainly metallurgical techniques, but apart from these methods, Japanese Patent Publication No. 57-2252
Irradiation of laser or plasma on the surface of the steel sheet after finish annealing as proposed in Japanese Patent Publication (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 for reducing iron loss by artificially reducing the magnetic domain width by 180 ° (magnetic domain refinement technology) was developed. With the development of this technology, the iron loss of the grain-oriented silicon steel sheet has been significantly 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 magnetic domain refining technique capable of withstanding strain relief annealing, a linear groove is introduced into the surface of a steel sheet after finish annealing of a unidirectional silicon steel sheet, and a magnetic domain effect is applied by utilizing the demagnetizing field effect of the groove. Has been industrialized to subdivide the technology (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.

In addition, Japanese Patent Publication No. 52-24499 discloses a method comprising removing a forsterite film formed after finish annealing of a silicon steel sheet, polishing the steel sheet surface, and then applying a metal plating to the steel sheet surface. A method has been proposed. However, this method has a disadvantage that although a low iron loss can be obtained at a low temperature, the metal is diffused into the silicon steel sheet when subjected to a high temperature treatment, so that the iron loss is rather deteriorated.

[0010] In this regard, the present inventors have previously disclosed in Japanese Patent Publication No. 63-54767 and the like, for solving the above disadvantages.
Si, Mn, Cr, Si, Mn, Cr, etc. are applied on a grain-oriented silicon steel sheet by dry plating (PVD) such as CVD, ion plating and ion implantation.
Ni, Mo, W, V, Ti, Nb, Ta, Hf, Al, Cu, Zr and B
It has been disclosed that an ultra-low iron loss can be obtained by forming one or two or more kinds of tension films selected from nitrides and carbides. This manufacturing method has made it possible to obtain extremely excellent iron loss characteristics as a material for power transformers and high frequency transformers, but nevertheless, it has sufficiently responded to recent demands for low iron loss. It was hard to be there.

Therefore, the present inventors have made a fundamental reexamination from all viewpoints in order to further reduce iron loss as compared with the prior art. That is, the inventor formed one or two or more kinds of tension films selected from various nitrides and carbides on the surface of a grain-oriented silicon steel sheet smoothed in a stable process to form an ultra-low iron loss. In order to obtain a product of the following, from the recognition that a fundamental review from the raw material composition of the unidirectional silicon steel sheet to the final processing step is necessary, from tracking the texture of the silicon steel sheet, Smoothness of steel sheet surface and final CVD and P
Intensive studies were conducted up to the VD processing step.

As a result, a plurality of types of ceramic tension coatings are formed on the surface of the silicon steel sheet regardless of whether the silicon steel sheet has a smooth surface or a silicon steel sheet having linear grooves. With regard to the coating, it was found that reducing the coefficient of thermal expansion toward the outside is extremely effective in reducing iron loss, and based on this, a new unidirectional silicon steel sheet with extremely low iron loss was newly developed. (JP-A-11-131252).

The thus obtained unidirectional silicon steel sheet has an extremely thin ceramic film having excellent adhesion and a tensile coating, and is capable of achieving not only an ultra-low iron loss but also an insulating property. Moreover, since it has an excellent space factor, it can be said that it is an ideal silicon steel sheet.

However, in order to form such a dense ceramic film, it is not only indispensable to carry out a treatment under a high plasma atmosphere in a vacuum, but also to use a material (for example, TiN) used for plasma coating. However, since pure Ti material is very expensive for film formation, and high-purity Si is very expensive for film formation of Si ₃ N ₄ ), there is a problem that the cost must be increased during industrialization. In addition, such as Si ₃ N ₄ and SiC
Although the Si-based ceramic coating has a small coefficient of thermal expansion, it has some problems in the film quality, and when subjected to a shearing or 180 ° bending test, the coating film is liable to crack due to the brittleness of the film. Has been pointed out.

[0015] The inventors of the present invention have further studied to reduce the manufacturing cost and improve the film quality.
Materials used for plasma coating include:
It has been found that ferro-silicon and meta-silicon containing relatively large amounts of impurities are more advantageous than high-purity Si. In other words, in the current ceramic coating of Si ₃ N ₄ and SiC, the magnetron sputtering method uses the viewpoint of the film quality of the ceramic, the uniformity of the film, the film forming speed, and the stability of the long-time continuous coating. Is most commonly used because it is the most reliable, but the purity of the Si target currently used in this magnetron sputtering method is the remaining (99.9999999 mass mass) used for the Si wafer.
% To 99.9999 mass% high purity Si) is used as a starting material.

However, the use of high-purity Si of about 99.9999999 mass% to 99.9999 mass%, even for the remaining silicon wafer, leads to an increase in the cost of the plasma coating material. It was pointed out that solving the cost reduction of get was a major problem. Therefore, the inventors have studied various silicon materials in order to solve the above problem. Among them, extremely inexpensive ferro-silicon and meta-silicon, which are generally used for adjusting the composition of steel products at the steelmaking stage, are used.
When used as Si target materials, it was found that these silicon materials are not only inexpensive, but also effectively improve the film quality and adhesion of the ceramic coating, and are also extremely effective in improving iron loss characteristics. (For example, JP-A-11-343579, JP-A-11-329819).

That is, a Si—N—O—C ceramic film containing oxygen and carbon in a Si ₃ N ₄ film, especially Fe or
Si-NOC-based ceramic films containing a small amount of Al, Ti, etc. not only have excellent film quality, but also effectively enhance the adhesion to silicon steel sheets, effectively contributing to the improvement of iron loss characteristics. Moreover, there is an advantage that the raw material cost is low.

[0018]

As described above, the surface of a silicon steel sheet is coated with Fe or A by magnetron sputtering.
By forming a Si-NO-C-based ceramic film containing a small amount of l, Ti, etc., coating of a ceramic film excellent in film quality and adhesion has become possible. However, in consideration of the industrial use of this method, the magnetron sputtering method has a very low film forming rate, so that a large number of targets are required in equipment, which causes not only an increase in cost but also a problem in control.

The present invention advantageously solves the above-mentioned problems. In forming a ceramic film, the film-forming speed can be effectively increased without deteriorating the film quality and adhesion, and hence the effect of imparting tension by the ceramic film. It is an object of the present invention to propose a method for manufacturing an ultra-low iron loss unidirectional silicon steel sheet capable of improving the manufacturing cost and productivity advantageously, together with a suitable dry plating apparatus for use in the implementation. .

[0020]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the formation of a film by magnetron sputtering is sufficient only in the initial stage. If an ultra-thin ceramic coating with high density and excellent adhesion is formed by magnetron sputtering, the electron beam method that allows high-speed deposition can be used after that, although the film quality is somewhat inferior. It has been found that the productivity and the production cost can be advantageously improved without substantially lowering the effect of imparting tension by the ceramic coating. The present invention is based on the above findings.

That is, the gist configuration of the present invention is as follows. 1. When forming a plurality of ceramic coatings on the surface of the annealed unidirectional silicon steel sheet, at least the first layer contains at least one selected from the group consisting of Fe, Al, and Ti using magnetron sputtering. Si-N
An ultra-low iron loss unidirectional silicon, wherein a ceramic coating of the same type or different types is formed on the ceramic coating by an electron beam method. Steel plate manufacturing method.

2. In the above item 1, the finish-annealed unidirectional silicon steel sheet has a surface with a thickness of 2 to 2 in a direction intersecting the rolling direction.
At intervals of 10 mm, width: 50-500 μm, depth: 0.1-50 μm
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising:

3. In the above 1 or 2, the finish-annealed surface of the grain-oriented silicon steel sheet is a surface which is not subjected to a smoothing treatment or a smoothing treatment, and is still a removal treatment of a forsterite film and / or an oxide film. A method for producing an ultra-low iron loss unidirectional silicon steel sheet.

4. In any one of the above 1 to 3, the thermal expansion coefficient of the ceramic coating is smaller toward the outer layer side, and the ceramic tension coating of the outermost layer is an ultra-low iron loss unidirectional silicon steel sheet characterized by having an insulating property. Production method.

[5] A coil-shaped steel strip is unwound in a high-vacuum chamber, and a device for simultaneously performing dry plating on one or both surfaces of the steel strip during rewinding, wherein an inlet side and an outlet side of the high vacuum chamber are provided. In each case, a preliminary vacuum chamber for carrying in and a preliminary vacuum chamber for carrying out the coil capable of reducing the pressure to near the degree of vacuum of the high vacuum chamber are provided, and a wound steel strip is provided at a front stage in the high vacuum chamber. One or more pairs of magnetron sputtering devices are disposed on each of the front and back sides of the steel strip, and at the subsequent stage, at least one pair of electron beam devices are also disposed on each of the front and back sides of the steel strip. Rating device.

6. In the above item 5, the coiled steel strip is
A dry plating apparatus characterized by being a finish-annealed unidirectional silicon steel sheet.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the experimental results that led to the present invention will be described. C: 0.075 mass%, Si: 3.41 mass%, Mn: 0.
078 mass%, Se: 0.020 mass%, Sb: 0.025 mass%, A
l: 0.020 mass%, N: 0.0073 mass% and Mo: 0.011 m
The ass% is contained, and the remainder is a silicon steel continuous cast slab having substantially the composition of Fe, and subjected to a heat treatment at 1350 ° C. for 5 hours and then subjected to hot rolling to obtain a hot-rolled sheet having a thickness of 2.0 mm. . 10
After performing uniform annealing at 80 ° C. for 2 minutes, rolling was performed twice with intermediate annealing at 1050 ° C. to obtain a final cold-rolled sheet having a sheet thickness of 0.23 mm.

Thereafter, the final cold-rolled sheet was processed as follows. On the surface of the final cold-rolled sheet, an etching resist ink containing an alkyd-based resin as a main component is subjected to gravure offset printing so that a non-applied portion has a width of approximately 200 perpendicular to the rolling direction:
The coating was performed so as to remain in a linear shape at a distance of 4 mm and baked at 200 ° C. for 3 minutes. At this time, the resist thickness was 2 μm. By performing electrolytic etching on the steel sheet coated with the etching resist in this way,
A linear groove having a width of 200 μm and a depth of 20 μm was formed, and then immersed in an organic solvent to remove the resist. At this time, the current density in the electrolytic etching was 10 A / d in a NaCl electrolytic solution.
m ² , treatment time: 20 seconds.

Then, after decarburization and primary recrystallization annealing were performed in wet H ₂ at 850 ° C., MgO (20 mass%), Al ₂ O ₃ (4
5mass%), Sr (OH) (10mass%), CaSiO ₃ (5mass%), SiO ₂ (20m
ass%), and after annealing at 850 ° C for 15 hours, at a rate of 850 ° C to 13 ° C / h.
After the temperature was raised to 1150 ° C. to develop secondary recrystallized grains strongly integrated in the Goss orientation, purification was performed in dry H ₂ at 1200 ° C.

After removing the surface coating of the product thus obtained and then smoothing the surface of the silicon steel sheet by chemical polishing, the magnetron sputtering method and the electron beam method as shown in FIG. Using a combined in-line continuous dry plating apparatus, a 0.7-μm thick Si—NO—C ceramic coating was formed.

In FIG. 1, reference numeral 1 denotes a preliminary vacuum chamber (a degree of vacuum: 10 ^-2 to 10 ^-3 Torr) for loading a coil;
2 is a coil of chemically polished unidirectional silicon steel sheet carried into the preliminary vacuum chamber 1 and 3 is a high vacuum tank (degree of vacuum: 10 ^-3)
To 10 ^-6 Torr), and 4 is a coil that is charged to a high vacuum chamber 3, Makikai steel sheet in a high vacuum tank 3 flows in the direction indicated by the number 5.

Reference numeral 6 denotes a magnetron sputtering chamber, in which a ferro-Si target 7 is provided.
A magnetron sputtering apparatus (maximum output: 20 kW) including three magnets 8 is provided on each of the front and back sides of the steel sheet. Here, the ferro-Si target 7 was prepared by melting 100 kg of ferro-silicon material in a vacuum melting furnace, shearing it to 12 mm × 127 mm × 1200 mm, and then performing a bonding process. In this bonding process, one side of the Si substrate is plated with Cu, and then the In substrate is used to attach the Si substrate to a Cu substrate (a magnet 8 can be placed on the back side of the water-cooled Cu substrate). -To be used as a get. The main components of the ferro-Si target are as follows: Si: 93.2 mass%, Fe: 5.
7 mass%, Al: 0.15 mass%, Ti: 0.11 mass%, C: 0.08 m
ass% and O: 0.082 mass%, containing a small amount of other trace elements.

An electron beam chamber 9 has an electron beam gun 1 therein.
A pair of 0 and 10 '(a maximum output of 200 kW is possible with a 90 ° deflection beam) is installed on the front and back sides of the steel plate. 11, 11 ′
Is an electron beam, 12 and 12 'are materials, and 13 and 13' are irradiation material supply devices. The materials 12 and 12 'irradiated with the electron beams 11 and 11' are vaporized and turned into a surface of a silicon steel sheet. It is a mechanism to adhere to. In addition, 14 is a coil immediately after the dry plating process, 15 is a preliminary vacuum chamber for carrying out (vacuum degree: 10 ^-2 to 10 ^-3 Torr), and 16 is a dry plating process moved into the preliminary vacuum chamber 15 for carrying out. The coil has already been used.

Using the above dry plating apparatus,
Si-N with thickness of 0.05μm by magnetron sputtering method and 0.65μm by electron beam method, totaling 0.7μm
A -OC-based ceramic coating was formed. The magnetic properties and adhesion of the silicon steel sheet thus obtained were as follows. Magnetic properties _{B 8: 1.92 T W 17/50:} 0.56 W / kg adhesion diameter: even if the 180 ° bending on a 5mm round bar no peeling

On the other hand, according to the conventional method, when the Si—N—O—C ceramic coating having a thickness of 0.7 μm is formed only by the magnetron sputtering method, the magnetic properties and adhesion are as follows. ₈ : 1.92 _{TW 17/50} : 0.54 W / kg Adhesion Adhesion: Even if 180 ° bending was performed on a 5 mm round bar, there was no delamination, but the processing time per coil was determined according to the present invention. When the number of cases according to the above was set to 1, it reached 13 times, and the productivity was far inferior.

[0036]

The directional silicon steel sheet according to the present invention is compatible with any of the conventionally known component compositions. Representative compositions are as follows. C: 0.01 to 0.08 mass% If C is less than 0.01 mass%, the suppression of hot rolled texture is insufficient and large elongated grains are formed to deteriorate magnetic properties. Since it takes a long time for decarburization in the charcoal process and it is not economical, it is preferable to set it to about 0.01 to 0.08 mass%.

Si: 2.0 to 4.0 mass% If Si is less than 2.0 mass%, sufficient electric resistance cannot be obtained, so that eddy current loss increases and iron loss deteriorates.
If it is more than 4.0 mass%, 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 mass%.

Mn: 0.01 to 0.2 mass% Mn is an important component that determines MnS or MnSe as a dispersed precipitation phase that affects secondary recrystallization of a unidirectional silicon steel sheet. If the amount of Mn is less than 0.01 mass%, the absolute amount of MnS or the like necessary for causing secondary recrystallization becomes insufficient, causing incomplete secondary recrystallization and increasing the number of surface defects called blisters. On the other hand, if it exceeds 0.2 mass%, 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, Mn is preferably set to about 0.01 to 0.2 mass%.

S: 0.008 to 0.1 mass%, Se: 0.003 to 0.1 mass% Both S and Se are 0.1 mass% or less, and especially S is
It is preferable that 0.008 to 0.1 mass% and Se be in the range of 0.003 to 0.1 mass%. Because these are 0.1 ma
If it exceeds ss%, the hot and cold workability deteriorates, and if it is less than the respective lower limit values, no particular effect is exerted on the primary grain growth suppressing function as MnS and MnSe. In addition, the addition of Al, Sb, Cu, Sn, B and the like, which are conventionally known as inhibitors, does not impair the effects of the present invention.

Next, the manufacturing process of the ultra-low iron loss unidirectional silicon steel sheet according to the present invention will be described. First, in order to smelt the raw material, not only an LD converter, an electric furnace, an open hearth furnace, and other known steelmaking furnaces can be used, but also vacuum melting and RH degassing can be used together.

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, RH degassing at the end of molten steel or at the time of ingot casting Can be added. In slab production, it is advantageous to use the continuous casting method because of economic and technical advantages such as cost reduction and uniformity of components or quality in the slab longitudinal direction. It does not hinder.

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 (also referred to as homogenizing annealing) in a temperature range of about 850 to 1100 ° C., if necessary, and then is subjected to one or two cold-pressing steps including intermediate annealing. Rolling is performed to obtain a final thickness, but in order to obtain a product having high magnetic flux density and low iron loss, attention must be paid to the final cold rolling rate (normally 55 to 90%). At this time, the upper limit of the product thickness is 0.5 from the viewpoint of minimizing the eddy current loss of the silicon steel sheet.
mm, and the lower limit of the plate thickness is preferably about 0.05 mm in order to avoid the adverse effect of hysteresis loss.

When forming a linear groove on the surface of a steel sheet,
It is particularly advantageous to carry out the process on a steel sheet which has finished the final cold rolling and has a product thickness. That is, on the surface of the final cold-rolled sheet or the steel sheet before and after the secondary recrystallization, the width: 50 to 500 μm, the depth: 0.1 at intervals of 2 to 10 mm in a direction crossing the rolling direction.
That is, a linear concave region of about 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 sheet is too remarkable, the magnetic flux density is lowered and it is not economical. This is because the conversion effect is reduced. If the width of the concave region is less than 50 μm, it will be difficult to use the demagnetizing effect, while if it exceeds 500 μm, the magnetic flux density will decrease and it will not be economical, so the width of the concave region will be in the range of 50 to 500 μm. Limited to. Furthermore, if the depth of the concave region is less than 0.1 μm, the demagnetizing effect cannot be effectively used.
If the thickness exceeds 50 μm, the magnetic flux density decreases and it becomes not economical. Therefore, the depth of the concave region is limited to the range of 0.1 to 50 μm. In addition, the forming direction of the linear concave region is optimally set to a direction perpendicular to the rolling direction, that is, the sheet width direction, but substantially the same effect can be obtained as long as it is within ± 30 ° with respect to the sheet width direction. .

Further, as a method of forming the linear concave area,
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, This is advantageous in that it can be carried out industrially stably, and that iron loss can be more effectively reduced by tensile 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 decarburizing annealing. This annealing makes the cold rolled structure the primary recrystallized structure,
{110} <00 in final annealing (also called finish annealing)
1> For the purpose of removing harmful carbon when secondary recrystallized grains having an orientation are developed, the process is performed, 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 usually performed by applying an annealing separating agent such as magnesia, and a forsterite film is simultaneously formed on the surface. However, in the present invention, even if a forsterite film is formed, an annealing separating agent which does not form such a forsterite film is more advantageous in order to remove this underlayer film in the next step. In other words, the content of MgO that forms a forsterite film is reduced (50 mass% or less), and instead CaO, Al ₂ O ₃ ,
An annealing separator having a high content ratio of CaSiO ₃ , SiO _{2 and the} like (50 mass% or more) is advantageous.

In the present invention, in order to develop a secondary recrystallized structure highly integrated in the {110} <001> orientation, annealing maintained at a low temperature of 820 ° C. to 900 ° C. is advantageous. Slow annealing at a heating rate of about 0.5 to 15 ° C./h may be used.

After this final (purification) annealing, the forsterite film and oxide film on the surface of the steel sheet are removed by a known chemical method such as pickling. After such pickling, a mechanical method such as cutting or polishing may be applied, or the pickling may be removed by combining with pickling. Then, the steel plate surface is smoothed. That is, after removing various coatings on the surface of the steel sheet as described above, chemical polishing, chemical polishing such as electrolytic polishing, mechanical polishing such as buff polishing, or a combination thereof, the center line average roughness. With Ra
Smooth the steel sheet surface to about 0.4μm or less.

In the present invention, it is not always necessary to smooth the surface of the silicon steel sheet. Therefore, in this case, there is an advantage that a sufficient iron loss reduction effect can be exhibited only by removing the forsterite film and / or the oxide film without performing the smoothing process accompanied by an increase in cost. Nevertheless, it is still advantageous to perform the smoothing process. At this stage, a concave groove can be introduced into the surface of the steel sheet. The grooves may be introduced by the same method as that used for the surface of the final cold-rolled sheet or the steel sheet before and after the secondary recrystallization.

After the above treatment, a ceramic tension coating is formed on the surface of the steel sheet by using a magnetron sputtering method and an electron beam method. Thus, in the present invention,
It is premised that two or more layers, that is, a plurality of layers, of such a ceramic film are formed, of which at least the first layer contains Si—N—O— containing at least one selected from Fe, Al and Ti. It is important to use a C-based ceramic film. This is because the above-mentioned Si—N—O—C
This is because the system ceramic film not only has excellent film quality by containing O and C in the film, but also has remarkably improved adhesion to the ground iron by the action of trace elements such as Fe.

As described above, in order to form a Si—N—O—C ceramic film excellent in film quality and adhesion,
The amount of Fe, Al, Ti, etc. in the Si target is Fe:
1.0 to 25.0 mass%, Al: 0.01 to 2.0 mass%, Ti: 0.01 to
It is preferably about 1.0 mass%. The ratio of each component in the coating is as follows: Si: 40 to 98 mass%, N: 20 to 70 ma.
ss%, O: 0.1-50 mass%, C: 1-20 mass%, Fe: 0.
1 to 15 mass%, Al: 0.01 to 10 mass%, Ti: 0.01 to 10 mass
% Is preferable. That is, if the content of each component is less than the lower limit, the effect of improving the film quality and adhesion of the ceramic coating and, consequently, the iron loss property is poor. This is because, as a result, the iron loss improving effect decreases.

And, as such a silicon material,
Commercially available inexpensive ferro-silicon and meta-silicon are particularly advantageously suitable, where the conventionally expensive Si
The cost reduction of Si targets, which had to be increased due to the use of wafers, is realized along with the improvement of iron loss characteristics. In addition, actually
To produce a Si target, ferro-silicon or meta-silicon may be dissolved, sheared to a predetermined size, and then subjected to a bonding process.

In order to prepare elements such as N, O, and C in the film, a coating atmosphere mainly composed of N ₂ gas is used.
It is also useful to mix an appropriate amount of O ₂ gas or C ₂ H ₂ gas.
The atmosphere gas component in this case is N ₂ gas: 30 to 95 v
ol%, O ₂ gas: 1~50vol%, C ₂ H ₂ gas: 1 to 30 vol%
The degree is preferred.

Next, according to the present invention, a magnetron sputtering method is carried out on a Si—N—O—C-based ultra-thin ceramic coating having good film quality and excellent adhesion formed by the magnetron sputtering method as described above. A ceramic film is formed by an electron beam method capable of forming a film 5 to 40 times faster than the method. In this case, the ceramic film formed by the electron beam method may be the same or different from the ceramic film formed by the magnetron sputtering method.

As described above, in the present invention, at least the first layer of the multi-layer coating must be a Si-NO-C-based ceramic coating, but the coating components constituting the other layers are not. There is no particular limitation, and Si-N
As long as the adhesiveness with the -OC-based ceramic coating is good, any conventionally known one is suitable. For example, Si, Mn, Cr,
Ni, Mo, W, V, Ti, Nb, Ta, Hf, Al, Cu, Zr and B
And the like. In forming such a coating, it is advantageous that the thermal expansion coefficient decreases toward the outside and that the outermost layer has insulating properties.

Here, the thickness of the ceramic film formed by the magnetron sputtering method is about 0.001 to 0.2 μm, preferably about 0.005 to 0.1 μm, which is 1/1/1 of the entire film thickness.
It is desirable to be about 20 to 1/5, and the total thickness with the ceramic film formed by the electron beam method is
It is preferably about 0.2 to 2.0 μm, preferably about 0.6 to 0.7 μm. In particular, if the total thickness is less than 0.2 μm, the effect of improving the iron loss is small because the effect of imparting tension is small.
On the other hand, if it exceeds 2.0 μm, the space factor and the magnetic flux density decrease.

Although the dry plating apparatus of the present invention has been described mainly for the case where a ceramic tension coating is formed on the surface of a unidirectional silicon steel strip, the use of the present invention apparatus is not limited to this. For a general steel strip such as a low-carbon cold-rolled steel strip or a stainless steel strip, it can be suitably used even when one or both surfaces thereof are simultaneously coated with a metal, an alloy or a ceramic coating. Not even.

[0060]

EXAMPLES Example 1 C: 0.071 mass%, Si: 3.35 mass%, Mn: 0.072 mass
%, Se: 0.020 mass%, Sb: 0.025 mass%, Al: 0.020 m
A continuously cast slab of silicon steel containing ass%, N: 0.0077 mass% and Mo: 0.011 mass%, with the balance being substantially Fe, was heated at 1350 ° C for 5 hours and then hot-rolled. And a hot-rolled sheet having a thickness of 2.2 mm. Then, after uniform annealing at 1050 ° C., cold rolling was performed twice with intermediate annealing at 1020 ° C. to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Then, after decarburization and primary recrystallization annealing in 840 ° C wet H ₂ ,
MgO (20mass%), Al ₂ O ₃ (40mass%), Sr (OH) (10mass%), CaS
After applying an annealing separator slurry having a composition of iO ₃ (10 mass%) and SiO ₂ (20 mass%), and then annealing at 850 ° C. for 15 hours, 85
The temperature was raised from 0 ° C to 1150 ° C at a rate of 10 ° C / h to develop secondary recrystallized grains that were strongly integrated in the Goss orientation.
It was subjected to purification treatment in H _2.

The oxide film on the surface of the silicon steel sheet thus obtained was removed, and a part thereof was further subjected to chemical polishing to smooth the surface. Next, on the surface of the silicon steel sheet, using the dry plating apparatus shown in FIG. 1, first, as a coating first layer, Si—N—O—
C-type ceramic membrane (coefficient of thermal expansion: 3.8 × 10 ^-6 / ° C)
An Al-based ceramic film (thermal expansion coefficient: 3.5 × 10 ⁻⁶⁾ was formed as the second layer by the electron beam method.
/ ° C) with a thickness of 0.5 µm. At this time, the Si target used for the magnetron sputtering method was manufactured as follows. The ferro-silicon material was melted in a 100 kg vacuum melting furnace, sheared to 10 mm × 127 mm × 457 mm, and then subjected to a bonding treatment. The main components of the ferro-silicon target are Si: 92.1 mass%, Fe: 7.
2 mass%, Al: 0.10 mass%, Ti: 0.09 mass%.

The magnetic properties and adhesion of the product thus obtained were as follows. (1) smoothing the applied was the case where the magnetic properties _{B 8: 1.94 T W 17/50:} 0.63 W / kg adhesion diameter: even if the 180 ° bending on a 10mm round bar no peeling (2) Pickling when subjected to treatment magnetic properties _{B 8: 1.93 T W 17/50:} 0.67 W / kg adhesion diameter: even if the 180 ° bending on a 10mm round bar no peeling

On the other hand, according to the conventional method, the magnetic characteristics and adhesion when a Si—N—O—C ceramic coating having a thickness of 0.53 μm was formed only by magnetron sputtering were as follows. ) smoothing processing alms was when magnetic properties _{B 8: 1.94 T W 17/50:} 0.58 W / kg adhesion diameter was also carried out 180 ° bending on a 5mm round bar as good as no peeling. However, when the processing time per coil was compared, the conventional method was 11 times as large as that of the present invention, and there was a great difference in productivity.

Example 2 C: 0.078 mass%, Si: 3.36 mass%, Mn: 0.068 mass
%, Se: 0.020 mass%, Sb: 0.025 mass%, Al: 0.020 m
A continuously cast slab of silicon steel containing ass%, N: 0.0076 mass% and Mo: 0.012 mass%, with the balance being substantially Fe, was subjected to heat treatment at 1360 ° C. for 4 hours, followed by hot rolling. And a hot-rolled sheet having a thickness of 2.2 mm. By cold rolling twice (intermediate annealing: 1050 ° C., 1 minute), a cold rolled sheet having a thickness of 0.23 mm was obtained. Then, the final cold rolled sheet was processed as follows. On the surface of this final cold-rolled sheet, an etching resist ink containing an alkyd-based 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 a spacing of 4 mm in a linear manner. 200 ℃
For 3 minutes. At this time, the resist thickness was 2 μm. By subjecting the steel sheet coated with the etching resist in this way to electrolytic etching, the width: 200 μm
A linear groove having a thickness of 20 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 were performed in wet H ₂ at 840 ° C., MgO (25 mass%), Al ₂ O ₃ (40
mass%), Sr (OH) (10mass%), CaSiO ₃ (5mass%), SiO ₂ (20ma
ss%), and after annealing at 850 ° C for 15 hours, at a rate of 850 ° C to 15 ° C / h.
After the temperature was raised to 1150 ° C. to develop secondary recrystallized grains strongly integrated in the Goss orientation, a purification treatment was performed in dry H ₂ at 1220 ° C. Thereafter, the oxide film on the surface is removed, and the surface is smoothed by chemical polishing. Then, the surface of the silicon steel sheet is first coated by magnetron sputtering using the dry plating apparatus shown in FIG. SiN _x film as a layer
A 0.06 μm thick layer was formed, and then an SiN—O—C ceramic film was formed as a second layer by an electron beam method to a thickness of 0.54 μm.
m, a total thickness of 0.6 μm was formed.

The magnetic properties and adhesion of the product thus obtained were as follows. Magnetic properties _{B 8: 1.92 T W 17/50:} 0.55 W / kg adhesion diameter: None be performed 180 ° bending on a 10mm round bar peeling For comparison, magnetron sputtering only Thickness: 0.6 [mu] m The magnetic properties and adhesion when a thick SiN _X film is formed are as follows. Magnetic properties B ₈ : 1.92 T W _17/50 : 0.53 W / kg Adhesion 180 ° bending on a 5 mm diameter round bar Even when the test was performed, the results were good with no peeling. However, when the processing time per coil was compared, the conventional method was 20 times as large as that of the present invention, and there was a great difference in productivity.

[0067]

As described above, according to the present invention, an ultra-low iron loss unidirectional silicon steel sheet which does not deteriorate the effect of imparting tension to the base iron and has excellent iron loss characteristics as compared with the conventional material can be obtained. It can be obtained at low cost under high productivity, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an in-line continuous dry plating apparatus suitable for use in the practice of the present invention. DESCRIPTION OF SYMBOLS 1 Preliminary vacuum chamber for carrying in coil 2 Coil of unidirectional silicon steel sheet 3 High vacuum chamber 4 Coil inserted in high vacuum chamber 5 Flow of unwound steel sheet 6 Magnetron sputtering chamber 7 Ferro-Si target 8 Magnet 9 Electron beam chamber 10, 10 'electron beam gun 11, 11' electron beam 12, 12 'material 13, 13' irradiation material supply unit 14 Coil immediately after dry plating 15 Preliminary vacuum chamber for unloading 16 Dry plated Coil of

Continuing on the front page F-term (reference) 4K026 AA03 AA22 BA08 BB05 BB10 CA16 CA18 CA27 DA02 EB04 EB11 4K029 AA02 AA25 BA41 BB02 CA01 CA05 DB21 4K033 AA02 PA04 PA05 PA07 RA04 TA04 4K044 AA02 AB02 BA12 BA18 CA19 BC02 BC01 BC08 CA02 HB11 HB14 HB19 NN06

Claims (6)

[Claims] When a plurality of ceramic coatings are formed on the surface of a grain-oriented silicon steel sheet that has been subjected to finish annealing, at least the first layer is formed using a magnetron sputtering method.
An Si-NO-C-based ceramic coating containing at least one selected from the group consisting of Fe, Al and Ti is formed, and then the same or different ceramic tension is applied on the ceramic coating by an electron beam method. A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising forming a film. 2. The steel sheet according to claim 1, wherein the finish-annealed unidirectional silicon steel sheet has a surface on the surface in a direction intersecting the rolling direction.
At intervals of 10 mm, width: 50-500 μm, depth: 0.1-50 μm
A method for producing an ultra-low iron loss unidirectional silicon steel sheet, comprising: 3. The method of claim 1, wherein the surface of the grain-oriented unidirectional silicon steel sheet subjected to finish annealing is not subjected to a smoothing treatment or a smoothing treatment to remove a forsterite film and / or an oxide film. A method for producing an ultra-low iron loss unidirectional silicon steel sheet, characterized by being a surface of a steel sheet. 4. The ultra-low iron loss according to claim 1, wherein the coefficient of thermal expansion of the ceramic coating decreases toward the outer layer, and the outermost ceramic tension coating has insulating properties. A method for producing a unidirectional silicon steel sheet. 5. An apparatus for unwinding a coil-shaped steel strip in a high vacuum chamber and simultaneously performing dry plating on one or both sides of the steel strip during rewinding, wherein the high vacuum chamber is charged. A pre-vacuum chamber for loading and a pre-vacuum chamber for unloading coils that can be evacuated to near the degree of vacuum of the high vacuum chamber are provided on the side and the outlet side, respectively. While one or more pairs of magnetron sputtering devices are arranged on each of the front and back sides of the unraveled steel strip, at the subsequent stage, at least one pair of electron beam devices are similarly arranged on each of the front and back sides of the steel strip. A dry plating apparatus characterized by the following. 6. The coiled steel strip according to claim 5,
A dry plating apparatus characterized by being a finish-annealed unidirectional silicon steel sheet.