JPH03215679A - Production of grain-oriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PURPOSE:To produce a grain-oriented silicon steel sheet excellent in iron loss and magnetic flux density by applying composite plating in which ceramic grains are dispersed to the surface of a grain-oriented silicon steel sheet smoothed to specific roughness and further forming an insulating film on the above. CONSTITUTION:After oxides are removed from the surface of a finish-annealed grain-oriented silicon steel sheet by means of pickling, low strain mechanical polishing using an elastic body, etc., the surface of the steel sheet is finished into a smooth surface of >=0.3mu center line average height by means of chemical polishing, electropolishing, etc. Subsequently, a plating film (about 0.1-5mu thickness) in which metal (Ni, Cr, Cu, Co, Fe, Zn, etc.) is used as a matrix and fine grains of ceramics (SiC, Al2O3, TiN, etc.) are dispersed is formed on the above surface by a composite plating method. Further, a phosphate solution, etc., are applied to this plated film and baked, by which an insulating film is formed. By this method, the grain-oriented silicon steel sheet in which iron loss is reduced and magnetic flux density is increased can be obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a grain-oriented silicon steel sheet that has extremely good magnetic flux density and iron loss, and in particular reduces iron loss and improves the surface of the steel sheet. A manufacturing method that can achieve an increase in magnetic flux density and significantly improve magnetic properties is described below.

(Prior art) The magnetic properties of grain-oriented silicon steel sheets are mainly defined by magnetic flux density and iron loss, and are represented by magnetic flux density (magnetic flux density Bll(T) at a magnetizing force of 800 A/m). A higher value is desirable, while a lower iron loss (represented by iron loss h, 7, at 1.7 T. 50 Hz) is desirable.

In addition, since grain-oriented silicon steel sheets are used in a laminated manner, it is necessary to apply an insulating film to the surface of the steel sheet, and the insulation film is usually formed during finish annealing at high temperatures in the manufacturing process of grain-oriented silicon steel sheets. It consists of two layers: a glass-like coating mainly made of forsterite, and a phosphate coating to provide insulation.

Incidentally, in recent years, research has been actively conducted to fully bring out the various properties of various substances through surface modification.

In the field of silicon steel, it has long been well known that a type of surface modification technology that smoothes the surface of a silicon steel sheet can significantly improve iron loss, mainly due to a reduction in hysteresis loss.

That is, if the surface is mirror-finished by removing the glass-like coating and the internal oxidation layer (subscale) on the surface layer, iron loss can be significantly improved.

However, as mentioned above, the surface of the silicon steel plate requires insulation, so it could not be used as a core material in its mirror-finished state. Furthermore, the phosphate coating described above has poor adhesion to mirror surfaces, so it could not be deposited directly on mirror surfaces. Therefore, various technical devices have been devised to solve these problems.

For example, Japanese Patent Application Laid-Open No. 49-96920 states, ``The surface of the steel plate is chemically polished or electrolytically polished, and then the mirror-like surface is plated with metals such as Zn, Sn, Cu, and Ni.
In addition, Japanese Patent Publication No. 56-4150 discloses that ``ceramics are vacuum-deposited on a smooth surface obtained by chemical polishing or electrolytic polishing.
application by chemical vapor deposition, sputtering or thermal spraying.

All of these techniques provide a solution to the problem that it is not possible to directly apply an insulating coat such as phosphate to a mirror-polished surface.

(Problems to be Solved by the Invention) However, none of the above methods has yet been industrialized. This is because, although it is shown in JP-A No. 49-96920 that it is possible to apply a coating while maintaining a smooth surface by applying metal plating,
If this treatment is actually performed, the metal plating will diffuse into the steel during strain relief annealing performed after processing on the silicon steel sheet, which is the iron core material, and will deteriorate the magnetism of the silicon steel sheet, and the space factor due to the plating layer will decrease. The decline is large, and the product value is also significantly reduced. On the other hand, with the technology disclosed in Japanese Patent Publication No. 56-4150, vacuum evaporation has problems with productivity because the reaction rate and processing area are limited, and chemical vapor deposition has problems with the reaction rate and film homogeneity. In addition, sputtering has lower productivity than vacuum deposition, and thermal spraying makes it extremely difficult to form a homogeneous thin film, resulting in a significant decrease in space factor.

For these reasons, the above method has not been implemented industrially.

Therefore, the present invention has developed a coating method that can uniformly form a highly adhesive insulating film over a wide area without deteriorating the excellent magnetism of the smoothed silicon steel sheet. The purpose of the present invention is to propose a method for producing grain-oriented silicon steel sheets with low iron loss and high magnetic flux density.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the inventors investigated various techniques for improving the magnetic properties by modifying the surface of grain-oriented silicon steel sheets. Composite plating with dispersed ceramic particles is applied to the surface of the silicon steel sheet, and an insulating film is formed on top of it to create a homogeneous and close adhesion that is advantageous for space factor without deteriorating magnetic properties. We succeeded in forming an insulating film with good properties.

That is, this invention removes surface oxides from a grain-oriented silicon steel sheet that has been finish annealed, and then makes the steel sheet surface a smooth surface with a centerline average roughness of 0.3 μm or less.
A grain-oriented silicon steel sheet with excellent magnetic properties, characterized in that a film containing ceramic particles dispersed in a metal matrix is formed on the surface of the steel sheet by plating, and an insulating film is further formed on this film. Manufacturing method and finish annealed grain-oriented silicon steel sheet, removing surface oxides, then removing the surface layer of the steel sheet by electrolytic treatment using a water-soluble halide, and plating treatment on the surface of the steel sheet. This is a method for producing an isotropic silicon steel sheet with excellent magnetic properties, which is characterized by forming a coating in which ceramic particles are dispersed using a metal as a matrix, and further forming an insulating coating on this coating.

It has also been found that insulation can be imparted to a plating film by increasing the concentration of ceramic particles in the surface layer of the film, leading to the development of a new manufacturing method that allows the insulating film to be omitted.

That is, the surface oxide of a grain-oriented silicon steel sheet that has been finish annealed is removed, and then the steel sheet surface is roughened to a center line average roughness of 0.
After forming a smooth surface of 3μ or less, the steel sheet surface is plated to create a film in which ceramic particles are dispersed using metal as a matrix, and the concentration of the ceramic particles relative to the matrix metal is increased from the steel sheet surface to the film surface. A method for producing a grain-oriented silicon steel sheet with excellent magnetic properties characterized by being coated with a plating film, and a process for removing surface oxides from the grain-oriented silicon steel sheet that has been finish annealed, and then applying a water-soluble After the surface layer of the steel plate is removed by electrolytic treatment using a halide, the surface layer of the steel plate is plated on the surface of the steel plate to form a film in which ceramic particles are dispersed using metal as a matrix, and the concentration of the ceramic particles relative to the matrix metal is reduced on the surface of the steel plate. This is a method for producing a grain-oriented silicon steel sheet with excellent magnetic properties, which is characterized by forming a highly plating film from the top to the surface of the film.

(for production) Next, this invention will be explained in detail in the order of steps.

The grain-oriented silicon steel sheet used in this invention is a steel sheet that has been subjected to secondary recrystallization treatment by a conventionally known method. That is, a steel ingot containing a grain-oriented silicon steel sheet material component is hot rolled, further cold rolled and annealed repeatedly to obtain a predetermined thickness, and then primary recrystallization annealing is performed. Next, an annealing separation material is applied to the surface of the steel plate and secondary recrystallization annealing is performed. Since this invention method improves magnetism by modifying the surface, it goes without saying that it has the effect of improving magnetism regardless of the inhibitor of the material or the manufacturing method such as rolling annealing method.

Incidentally, typical component compositions are as shown below.

C: 0.01 to 0.10 wt% (hereinafter simply referred to as %) C is an element that is useful not only for uniform refinement of the structure during hot rolling and cold rolling, but also for the development of Goss orientation, It is preferable to add at least 0.01% or more. But 0.
If the content exceeds 10%, the Goss orientation will be disturbed, so the upper limit is preferably about 0.10%.

St: 2.0 to 4.5% Si increases the specific resistance of the steel sheet and effectively contributes to reducing iron loss, but if it exceeds 4.5%, cold rollability is impaired;
If it is less than 0%, not only will the resistivity decrease, but also randomization of crystal orientation will occur due to α-γ transformation during the final high-temperature annealing performed for secondary recrystallization and purification, resulting in a sufficient iron loss improvement effect. is not obtained, the amount of Si is preferably about 2.0 to 4.5%.

Mn: 0.02 to 0.12% Mn is at least 0.02% to prevent hot deterioration
It is preferable to set the upper limit at about 0.12%, since too much content deteriorates the magnetic properties.

Inhibitors include so-called MnS, MnSe and AIN inhibitors. In the case of MnS+MnSe, at least one selected from Se and S: o
．． oos~0.06% Se and S are both effective elements as inhibitors that control secondary recrystallization of grain-oriented silicon steel sheets. From the viewpoint of ensuring suppressive power, it is necessary to have at least about 0.005%, but if it exceeds 0.06%, the effect will be impaired, so the lower and upper limits are respectively 0.01%. 0
．． It is preferable to set it to about 0.06%.

In the case of AIN type, Al: 0.005-0.10%, N: 0.0
Regarding the range of 04 to 0.015% AI and N, due to the same reason as in the case of MnS and HnSe systems mentioned above,
The above range is set. Here, the above-mentioned MnS, MnS
The e system and the AIN system can each be used in combination.

As the inhibitor component, the above-mentioned S. Se. AI
Besides, Cu. Sn. CrsGe, Sb+Mo
+ 4e+ Bt and P etc. are also suitable, so
They can also be contained together in small amounts. Here, the preferred addition ranges of the above components are Cu, Sn, and C.
r: 0.01-0.15%, Ge, Sb. Mo
, Te, Bi: 0.005-0.1%, P: 0
．． 01 to 0.2%, and each of these inhibitor components can be used alone or in combination.

Next, oxides on the surface generated during final annealing are removed to finish the steel plate surface into a smooth surface with a center line average roughness of 0.3 μm or less. At this time, it is necessary to avoid leaving large plastic strain on the surface since this will deteriorate the magnetic properties of the product.

Therefore, it is preferable to use pickling or low-strain mechanical polishing using an elastic material to remove oxides. Thereafter, the surface is smoothed to a predetermined roughness by chemical polishing or electrolytic polishing. Here, it is necessary to finish the surface of the steel plate to 0.3 μm Ra or less.

This is because if the surface roughness of the steel plate exceeds 0.3 μrn Ra, sufficient reduction in hysteresis loss cannot be obtained.

Also, as a means of smoothing other than chemical polishing and electrolytic polishing,
Electrolytic treatment with a water-soluble halide may also be used.

Here, water-soluble halides include HCI, NH4C
1 and various metal chlorides, acid, alkali, alkaline earth and other metal salts with F, Br, I as anions, or water-soluble ammonium salts;
Furthermore, it means a water-soluble type of fluorine (BF4 salt) or silicone fluoride (SiF6 salt). Although electrolytic treatment using an aqueous solution of these halides cannot produce a so-called mirror surface like chemical polishing or electrolytic polishing, if electrolytic treatment is applied to reduce the surface layer over a thickness of 3 μm or more, the hysteresis loss can be reduced in the same way as a mirror surface. effect can be obtained.

Then, the smoothed steel plate surface is coated with a composite plating method.
Coat with a thin plating film. The plating film is made by dispersing ceramic particles in a metal matrix.
It also has excellent adhesion to the smooth surface of steel plates, and even after strain relief annealing, the plating matrix metal has ceramic fine particles dispersed in it, so it hardly diffuses into the steel, so it does not deteriorate the magnetism. The adhesion of the insulating film formed on the plating film can also be improved. Furthermore, during the baking process of the insulating film, tension due to the intermediate plating film layer is applied to the surface of the steel sheet, further improving magnetism.

The metal matrix in this plating film is N
i, Cr. Cu, Co, Fe, and Zn are particularly suitable, and S is particularly suitable as the ceramic fine particles to be dispersed.
iC. Carbide such as WC, ^120i+ TiOz,
Oxides such as SiOz, nitrides such as TiN, etc. are advantageously suitable.

Furthermore, if the thickness of the coating is less than 0.1 μm, it is difficult to obtain a homogeneous film, while if the thickness exceeds 5 μm, cracks will occur in the plating layer and the space factor will decrease when an insulating coating is applied. Since this may also lead to a decrease in the thickness of the film, it is preferable that the thickness of the coating is in the range of 0.1 to 5 μm.

Here, the composite plating method may be either electroplating or electroless plating.Specifically, it is as follows.

First, electroplating is performed by placing an electrode in a bath in which ceramic fine particles to be dispersed are suspended, a material to be plated being placed at the cathode, and a matrix metal being placed at the anode. The plating solution may be any metal salt solution that supplies ions of the same metal as the matrix metal.

The ceramic fine particles suspended in the bath are transported to the surface of the material to be plated, which is used as a cathode, by the flow caused by the stirring of the bath.
Collision with a surface. The fine particles that collide with the surface are embedded in the matrix as metal is electrolytically deposited, forming a composite plating layer.

On the other hand, electroless plating forms a plating film on the material surface by immersing the material in a bath containing a metal salt solution of the matrix metal and a reducing agent.In this invention, ceramic fine particles are added to the bath. Leave it suspended.

Similarly, in the case of electroless plating, fine particles that collide with the surface of the material to be plated as the metal is reduced and deposited are embedded in the matrix, forming a composite plating layer.

Next, after a plating film is formed, a phosphate solution, for example, is applied to form an insulating film. Of course, a conventionally known tension-applying insulating film forming liquid may be applied. Application may be performed using a roll coater or by a spray method.

The above-mentioned coating film is baked, and at that time, the intermediate plating film imparts tension to the surface of the steel sheet.

Furthermore, when forming a plating film on the smoothed steel sheet surface, the concentration of dispersed ceramic particles relative to the matrix metal is increased from the steel sheet surface to the film surface, that is, a gradient is created in the ceramic particle concentration in the film thickness direction. By imparting insulation to the surface layer of the coating, the insulation coating can be omitted and the space factor of the steel plate can be improved.

Here, the concentration gradient is preferably matrix-rich on the base metal side and ceramic-rich on the surface layer side.

Particularly preferred is a coating whose surface layer composition is 100% ceramic. This is because the more plating matrix metal is present in the surface layer, the better the insulation can be achieved. The concentration gradient can be achieved by, for example, changing the suspension concentration of the plating solution or the relative movement between the solution and the material to be plated.

Even when a concentration gradient of ceramic particles is provided in this plating film, the film thickness is preferably 0.5 to 5 μm. That is, if the thickness is less than 0.5 μm, it is impossible to create a concentration gradient in the direction of the film thickness, while if it exceeds 5 μm, there is a risk that krasok will enter the film.

Note that an ordinary insulating film may be further formed on the surface of the plating film imparted with insulation.

(Example) Implementation ■ Using MnSe as an inhibitor, the surface oxides of a finish-annealed grain-oriented silicon steel plate (0.23 mm thick) containing 3.41% Si were removed by pickling with hydrochloric acid, and then After forming a plating film by performing the treatments under the conditions shown in Table 1, a phosphoric acid-based insulating film was applied on the plating film.

The magnetic properties, adhesion, and space factor of the steel sheet thus obtained are shown in Table 1 in comparison with the as-finished annealed material (comparative example).

As can be seen from the table, the inventive method was able to efficiently form an insulating film that had good adhesion and could increase the space factor without degrading the excellent magnetic properties.

Among the evaluations in the same table, the adhesion of the film was first evaluated by wrapping a steel plate around a cylindrical test rod, then stretching it and observing the peeling state of the film.

In addition, the space factor is determined from the ratio of the calculated thickness and the measured thickness obtained from the weight after forming the insulating film, and the variation in film thickness is determined by the board width 50.
The variation in plate thickness in sample materials of cm was measured.

Finish annealed grain-oriented silicon steel plate (0.23 mm thick) containing 3.20% Si and using λ AIN as an inhibitor.
After removing surface oxides by free abrasive mechanical polishing using SiC abrasive grains with an average particle size of 5 μm and a nylon brush, a plating film was formed under the conditions shown in Table 2. A phosphoric acid-based insulating film was applied on the film.

Table 2 shows the magnetic properties, adhesion, and space factor of the copper plate thus obtained in comparison with the as-finished annealed material (comparative example).

As can be seen from the table, the inventive method was able to efficiently form an insulating film that had good adhesion and could increase the space factor without degrading the excellent magnetic properties.

The surface oxides of a finish-annealed grain-oriented silicon steel plate (0.23 mm thick) containing 3.20% Si and using MnSe as an inhibitor were removed by pickling with hydrochloric acid, and then the materials shown in Table 3 were removed. A plating film was formed under each condition.

The magnetic properties, adhesion, and space factor of the steel sheet thus obtained are shown in Table 3 in comparison with the as-finished annealed material (comparative example).

As can be seen from the table, the method of the present invention was able to efficiently form a plating film that had good adhesion and could significantly increase the space factor without degrading the excellent magnetic properties.

Finish annealed grain-oriented silicon steel plate (0.23 mm thick) containing 3.1S% Si and using the real tip ^IN as an inhibitor.
After removing the surface oxides by free abrasive S mechanical polishing using SiC abrasive grains with an average particle size of 5 μm and a nylon brush, a plating film was formed by performing the treatments under the conditions shown in Table 4. A phosphoric acid-based insulating film was applied on the plating film.

Table 4 shows the magnetic properties, adhesion, and space factor of the steel sheet thus obtained in comparison with the as-finished annealed material (comparative example).

As can be seen from the table, the inventive method was able to efficiently form an insulating film that had good adhesion and could increase the space factor without degrading the excellent magnetic properties.

(Effects of the Invention) According to the present invention, a grain-oriented silicon steel sheet with significantly superior iron loss and magnetic flux density can be manufactured, and therefore a manufacturing method with high productivity and great industrial value can be realized. Furthermore, since a coating with excellent adhesion can be obtained, it is possible to increase the space factor of the grain-oriented silicon steel sheet, and the insulation coating can be omitted, especially when the plating coating has a concentration gradient of ceramic particles. possible, and can significantly increase the floor space factor.

Claims (4)

[Claims] 1. After removing the surface oxides from the finish-annealed grain-oriented silicon steel sheet and making the steel sheet surface smooth with a centerline average roughness of 0.3 μm or less, metal is coated on the surface of the steel sheet by plating. A method for producing a grain-oriented silicon steel sheet with excellent magnetic properties, characterized by forming a plating film in which ceramic particles are dispersed as a matrix, and further forming an insulating film on the plating film. 2. Surface oxides are removed from the finish-annealed grain-oriented silicon steel sheet, the surface layer of the steel sheet is removed by electrolytic treatment using a water-soluble halide, and then metal is applied to the surface of the steel sheet by plating. A method for producing grain-oriented silicon steel sheets with excellent magnetic properties, characterized by forming a plating film in which ceramic particles are dispersed as a matrix, and further forming an insulating film on the plating film. 3. After removing the surface oxides from the finish-annealed grain-oriented silicon steel sheet and making the steel sheet surface smooth with a centerline average roughness of 0.3 μm or less, metal is coated on the surface of the steel sheet by plating. A directional silicone film with excellent magnetic properties characterized in that it is a film in which ceramic particles are dispersed with a matrix of Manufacturing method of raw steel plate. 4. Surface oxides are removed from the finish-annealed grain-oriented silicon steel sheet, the surface layer of the steel sheet is removed by electrolytic treatment using a water-soluble halide, and then metal is applied to the surface of the steel sheet by plating. Directional silicon with excellent magnetic properties, characterized by a film in which ceramic particles are dispersed as a matrix, and a plating film is formed that increases the concentration of the ceramic particles to the matrix metal from the surface of the steel plate to the surface of the film. Method of manufacturing steel plates.