JPH06287764A - Low core loss grain-oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To obtain a low core loss and high occupying volume rate grain- oriented silicon steel sheet having a film with high tension by forming a film having a specified Young's modulus, thermal expansion coefficient and crystal size on the surface by a specified thickness with tight adhesion. CONSTITUTION:On the surface of a grain oriented silicon steel sheet, a film constituted of a compound contg. Li, B, Mg, Al, Si, P, Ti, V, Mn, Fe, Co, Ni, Cu, Zr, Sn, Ba or the like is formed to make up into 0.2 to 5mum thickness. This film has >=100GPa Young's modulus and in which the difference in the thermal expansion coefficient with that of the base metal steel sheet is regulated to >=2X1.0<-6>/K. Moreover, this film contains 10 to <95wt.% crystals having >=10nm average crystal size and 5 to <90% other crystals and amorphous ones, and the average grain size of the crystal grains is regulated to <=1000nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented electrical steel sheet having a film containing a crystalline phase formed on its surface. In particular, the present invention relates to a grain-oriented electrical steel sheet having good adhesion and having a coating film that imparts a large tension to the base steel sheet, on which the iron loss is remarkably improved and the space factor is high.

[0002]

2. Description of the Related Art Grain-oriented electrical steel sheets are (010), [00
It has a crystallographic structure whose main direction is [1] and is often used as a magnetic iron core material, and it is required to reduce iron loss in order to reduce energy loss. As a means for reducing the iron loss of grain-oriented electrical steel sheets, there is a method of irradiating a laser beam on the surface of the steel sheet after finish annealing to give local strain, and thereby subdividing magnetic domains.
No. 5 is disclosed. Further, Japanese Patent Application Laid-Open No. 62-86175 discloses, for example, Japanese Patent Laid-Open No. 62-86175, which discloses a magnetic domain subdivision means which does not lose its effect even after performing stress relief annealing (stress relief annealing) after iron core processing.

[0003] On the other hand, it is known that the grain orientation of magnetic grained steel sheets also causes the magnetic domains to be subdivided by applying external tension, resulting in a decrease in iron loss. According to the study by the inventors,
It has been known that applying tension up to about 1.5 kgf / mm ² effectively reduces iron loss. Current grain-oriented electrical steel sheets usually have a forsterite primary coating formed during finish annealing (secondary recrystallization annealing) and a colloidal silica-phosphate-based secondary coating formed thereon. Cage,
With these coatings, when the plate thickness is 0.23 mm, about 1 kgf /
A tension of mm ² is applied. Therefore, in the case of the current coating, there is still room for iron loss improvement by applying a larger tension, but increasing the applied tension by thickening the coating is not preferable because the space factor decreases.

As another method for improving the iron loss of grain-oriented electrical steel sheets, the unevenness of the steel sheet surface after finish annealing and the internal oxide layer near the surface are removed to give a mirror finish, and the surface is metal-plated. The method of applying
A method of forming a tension film on the surface thereof is disclosed in, for example, JP-B No. 56-4150 and JP-A No. 61-2.
No. 01732, Japanese Examined Patent Publication No. 63-54767, and Japanese Patent Laid-Open No. 2-213483. Even in this case, the greater the tension applied to the steel sheet by the coating, the greater the iron loss improving effect. From these things, a thin film having a large effect of applying tension to the steel sheet has been desired.

[0005]

SUMMARY OF THE INVENTION The present invention solves these problems in the prior art, and has excellent adhesion, and has a coating on the surface that imparts a large amount of tension to a steel sheet even if it is thin. And to provide a grain-oriented electrical steel sheet having a high space factor.

[0006]

The inventors of the present invention contain a certain amount of a crystal phase in a film and control the coefficient of thermal expansion, Young's modulus, crystallite size, and crystal grain size at the grain level of the crystal. By doing so, it was found that the improvement of iron loss by applying tension and the high space factor were effectively achieved, and the present invention was completed.

That is, the gist of the present invention is as follows. (1) A crystal having a Young's modulus of 100 GPa or more and / or a thermal expansion coefficient difference of 2 × 10 ⁻⁶ / K or more with the base material steel plate and having an average crystallite size of 10 nm or more is 10 in weight ratio.
% Or more and the average particle size of the crystal particles is 1000 nm
A low iron loss grain-oriented electrical steel sheet having the following coating formed on its surface in a thickness of 0.2 μm or more and 5 μm or less. (2) Crystals having a Young's modulus of 100 GPa or more and / or a thermal expansion coefficient difference of 2 × 10 ⁻⁶ / K or more with the base material steel sheet and having an average crystallite size of 10 nm or more in a weight ratio of 10
% Or more and less than 95%, and crystals of 5% or more and less than 90% which do not meet the above requirements and are formed by the reaction of the above-mentioned crystals with other coating film constituent components and / or base steel plate components, and the average of the constituent crystal particles Particle size is 10
A low iron loss grain oriented electrical steel sheet having a coating film having a thickness of 00 nm or less and having a thickness of 0.2 μm or more and 5 μm or less.

(3) It comprises 10% or more and less than 95% by weight of crystals having an average crystallite size of 10 nm or more, and mainly 5% or more and less than 90% of an amorphous phase formed as a result of melting in the baking step. And the average particle size of crystalline particles is 1
The low iron loss grain-oriented electrical steel sheet according to (2), wherein a coating film having a thickness of 000 nm or less is formed on the surface with a thickness of 0.2 μm or more and 5 μm or less. (4) Young's modulus of 100 GPa or more, or base material steel plate and 2
Crystals having a thermal expansion coefficient difference of × 10 ^-6 / K or more are Li,
B, Mg, Al, Si, P, Ti, V, Mn, Fe, C
The low iron loss grain-oriented electrical steel sheet according to (1), which is one kind or two or more kinds of compounds containing at least one kind of o, Ni, Cu, Zr, Sn and Ba as a component.

(5) The low iron loss grain oriented electrical steel sheet according to (3), wherein the amorphous phase formed as a result of melting mainly in the baking step is a glass phase containing B and P as one component. (6) Young's modulus of 100 GPa or more, or base material steel plate and 2
The crystal having a difference in thermal expansion coefficient of × 10 ^-6 / K or more is aluminum borate, and the amorphous phase is a glass phase containing B as one component (3). .

[0010]

The first grain-oriented electrical steel sheet of the present invention is 100 GPa.
Young's modulus or more, or difference in thermal expansion coefficient of 2 × 10 ^-6 / K or more from the base steel sheet, and the average crystallite size is 10 nm
It has a coating containing the above-mentioned crystals in an amount of 10% or more by weight and having an average particle diameter of crystal particles of 1000 nm or less on the surface, and this coating imparts a large tension to the steel sheet to reduce iron loss. Has been achieved. Conventionally, as a characteristic required for a coating for imparting a large tension to a steel sheet,
It has been pointed out that the difference in coefficient of thermal expansion from the steel sheet is large, the elastic modulus is large, and the adhesion is good (Japanese Patent Publication No. 53-28375), but the Young's modulus of 100 GPa or more in the coating, ^{Alternatively} , these are effectively achieved by containing a crystal having a coefficient of thermal expansion difference of 2 × 10 ⁻⁶ / K or more with the base steel sheet in an amount of 10% or more by weight.

To obtain high tension, preferably 150 GP
It is Young's modulus of a or more or 4 × 10 ⁻⁶ / K or more, and more preferably 200 GPa or more of Young's modulus or 6 × 10 ⁻⁶ / K or more of thermal expansion coefficient difference.
In particular, a coating film containing crystals satisfying both of the Young's modulus and the difference in coefficient of thermal expansion satisfies extremely large tension and achieves low iron loss. The reason for limiting this to crystals having an average crystallite size of 10 nm or more is that the amorphous phase is usually generated by melting in the baking process and solidification in the cooling process, so the melting point is so high. It is because there is a possibility that the characteristics of the coating may be partially remelted in the subsequent stress relief annealing step, and that the inclusion of the crystal phase does not cause any change in the stress relief annealing, resulting in stable characteristics. A coating can be obtained.

Crystals having the above characteristics and capable of imparting a large tension to the steel sheet include Li, B, Mg, Al, Si,
P, Ti, V, Mn, Fe, Co, Ni, Cu, Zn,
An oxide, a nitride, a carbide, an oxynitride, etc., containing at least one of Zr, Sn, and Ba as components, among which Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , MgO.
_{Al 2 O 3, 2MgO · SiO} 2, MgO · SiO 2,
2MgO ・ TiO ₂ , MgO ・ TiO ₂ , MgO ・ 2T
iO ₂ , Al ₂ O ₃ · SiO ₂ , 3Al ₂ O ₃ · 2Si
_{O 2, Al 2 O 3 ·} TiO 2, ZnO · SiO 2, Zr
O ₂ · SiO ₂ , ZrO ₂ · TiO ₂ , 9Al ₂ O ₃ ·
2B ₂ O ₃ , 2Al ₂ O ₃ · B ₂ O ₃ , 2MgO · 2A
l ₂ O ₃ .5SiO ₂ , Li ₂ O.Al ₂ O ₃ .2Si
O ₂ , Li ₂ O ・ Al ₂ O ₃・ 4SiO ₂ , BaO ・ A
l ₂ O ₃ · SiO ₂ satisfies the above crystal characteristics,
One of these is preferably used alone or in a mixture of two or more.

Among the above compounds, Al ₂ O is used as a crystal phase which brings about a remarkable reduction in iron loss by applying a particularly high tension.
₃ , SiO ₂ , TiO ₂ , ZrO ₂ , MgO.Al ₂ O
_{3, 2MgO · SiO 2, MgO} · SiO 2, 2MgO
_{· TiO 2, MgO · TiO 2} , MgO · 2TiO 2,
Al ₂ O ₃ · SiO ₂ , 3Al ₂ O ₃ · 2SiO ₂ , A
l ₂ O ₃ · TiO ₂ , ZrO ₂ · SiO ₂ , 9Al ₂ O
_{3 · 2B 2 O 3, 2Al} 2 O 3 · B 2 O 3, 2MgO ·
2Al ₂ O ₃ · 5SiO ₂ , Li ₂ O · Al ₂ O ₃ · 2
_{SiO 2, Li 2 O · Al} 2 O 3 · 4SiO 2 is preferably used.

The content of these crystal phases in the film is 10%.
If it is above, there is no particular problem, and although it causes a reduction in iron loss of the steel sheet, it is 30% to stably impart high tension.
The above is preferable, and more preferably 50% or more is contained. Furthermore, since the coating is usually inorganic, its properties depend not only on the crystals it contains but also on the microstructure at the grain level. By applying tension to the steel sheet, a compressive stress is applied to the coating, but in order to withstand this and to stably impart a high tension, it is preferable that the crystal grains constituting the coating are not large, preferably 1000 nm or less,
More preferably, it is 500 nm or less. The thickness of the coating is required to be 0.2 μm from the viewpoint of effective tension application, and is preferably 0.5 μm or more. If it is too thick, the space factor is lowered, so that the thickness is preferably 5 μm or less. Especially 0.
A thin coating is essential for thin steel plates less than 23 mm.

In the surface coating of the second low iron loss grain-oriented electrical steel sheet of the present invention, in addition to crystals satisfying the above requirements (hereinafter crystal phase (A)), other crystals (hereinafter crystal phase (B)). , Or 5% to 90% by weight of the amorphous phase
Contains less than. Of these, the crystalline phase (B) is generated as a result of the reaction of the crystalline phase (A) with other components in the baking step, and the properties such as Young's modulus and thermal expansion coefficient are requirements of the crystalline phase (A). Since the above condition is not satisfied, the contribution to the application of tension to the steel sheet is small. However, it has a function of significantly improving the adhesion between the coating and the steel sheet by the reaction in the baking step, and as a result, it is an essential component of the tension coating.

The film constituents in this case include not only the other components in the tension film but also the components in the undercoat already formed on the steel sheet before forming the tension film. In particular, when forming a tension-imparting coating on a mirror-finished steel sheet surface with the intention of achieving a markedly low iron loss, securing adhesion is a major problem. However, by including the crystalline phase (B) of the present invention in the coating, The adhesion is remarkably improved. The crystal phase (B) is not particularly limited, and any crystal phase (B) can be suitably used as long as it is a result of the reaction.

On the other hand, the amorphous phase also exists in the tension film and has a function of improving the adhesion. This amorphous phase is formed as a result of melting at least a part of the above-mentioned crystalline phase (B) produced by the reaction or the film-forming constituents other than the crystalline phase (A) alone in the baking step. The amorphous phase is also not particularly limited, but a glass phase containing B and P as one component, such as borosilicate glass or phosphate glass, is preferable from the viewpoint of heat resistance, stability, imparting tension to the film. It is preferably used.

The content of the crystalline phase (B) or the amorphous phase in the coating film is 5% or more and less than 90% by weight, and there is no particular problem, and the amorphous phase coexisting with the crystalline phase (A) is 90%. It is possible to contain up to less than%. However, since these components are not direct tension-imparting components, it is preferably 5
% Or more and less than 70%, and more preferably 5% or more and less than 50%.

The coating described so far is not only formed directly on the surface of the steel sheet base metal which has been subjected to the secondary recrystallization annealing, but some surface treatment is applied to the surface in order to enhance the adhesion. Even if formed on the surface of the applied steel sheet, a grain-oriented electrical steel sheet with low iron loss can be obtained. In addition, a grain-oriented electrical steel sheet with low iron loss can be obtained even when it is formed on the surface of a forsterite primary coating formed by ordinary secondary recrystallization annealing, or a colloidal silica-phosphate-based secondary coating. To be

The low iron loss grain oriented electrical steel sheet having a coating on its surface has been described above. As a coating showing a particularly remarkable tension imparting and contributing to the reduction of iron loss, aluminum borate as the crystal phase A It is composed of a glass phase containing B as one component as a crystalline phase, and other components inevitably formed. 9 Al ₂ O _{3 for} aluminum borate
· 2B ₂ O _3, 2Al the composition such as ₂ O ₃ · B ₂ O ₃ is present, we both have a Young's modulus of about 200 GPa, the steel sheet in the thermal expansion coefficient of about 4 × 10 ^-6 / K And 8 × 10
^-6 / K or more. The glass phase containing B as a component remarkably enhances the adhesion between the coating and the base steel sheet or the already formed primary and secondary coatings by forming borosilicate glass or aluminoborosilicate glass. ing. The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0021]

【Example】

Example 1 The sol shown in Table 1 was prepared by the following method. Al ₂
O ₃ sol is commercially available boehmite powder (CONDEA VI
Distilled water was added to STA (Dispal) and stirred to form a uniform sol. SiO ₂ , TiO ₂ , Z
The pH of the rO ₂ sol was adjusted to a commercially available sol (Nissan Chemical Co., Ltd.) as necessary. Regarding the complex oxide sol, the above oxide sol is blended so as to have the composition of the complex oxide,
Obtained by stirring until uniform.

Among them, the MgO component is a fine powder obtained by hydrolyzing magnesium diethoxide, and the BaO component is a sol produced by hydrolyzing barium methoxide obtained by dissolving metal barium in methanol. As the ZnO component, a commercially available ultrafine powder was dispersed and the pH was adjusted before use. Li ₂ O ・ A
l ₂ O ₃ · 2SiO ₂ , Li ₂ O · Al ₂ O ₃ · 4Si
O ₂ was prepared based on a commercially available lithium silicate sol.

A steel sheet having a forsterite coating (primary coating) after finish annealing of a plate thickness of 0.2 mm containing 3.3 wt% of these sols, and a phosphate coating (2) A predetermined amount was applied to the steel sheet on which the following coating) was formed, dried and gelled, and then baked in nitrogen at 1000 ° C. for 60 seconds to obtain a uniform coating. The properties of the coating are also shown in Table 1.

The crystallite size was calculated from the spread of the peak width, using a metal Si powder having extremely good crystallinity as a standard. The appearance and adhesion of the coating were very good, and all the coatings on one side were removed, and the tension, saturation magnetic flux density before and after the coating formation, and iron loss calculated from the degree of bending are shown in Table 1. From this, it is understood that a magnetic steel sheet having a significantly improved iron loss value due to the film formation is obtained.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

Example 2 A coating solution prepared by adding the components shown in Table 2 to a sol prepared in the same manner as in Example 1 was prepared, and the two types of coated steel sheets of Example 1 were treated with an acid treatment method and alumina. After applying a predetermined amount to two types of mirror-finished steel sheets produced by the coating secondary recrystallization method, drying and gelling, baking at 900 ° C. for 60 seconds in a nitrogen atmosphere containing 4% by volume of hydrogen. To obtain a uniform coating. Table 2 shows the properties of the coating and the magnetic properties of the steel sheet. From this, it can be seen that a magnetic steel sheet having a significantly improved iron loss value due to the film formation is obtained.

[0030]

[Table 5]

[0031]

[Table 6]

[0032]

[Table 7]

[0033]

[Table 8]

[0034]

INDUSTRIAL APPLICABILITY According to the present invention, iron loss is remarkably improved and a high space factor is obtained by having a coating film on the surface of the steel sheet, which contains a crystalline phase having a specific property to give a sufficient tension. A grain-oriented electrical steel sheet is provided. In particular, this coating shows good adhesion even to a steel sheet that is smoothed to a state close to a mirror surface with the intention of significantly reducing iron loss,
It brings a sufficient iron loss improving effect, and its industrial effect is enormous.

Claims (6)

[Claims] 1. A crystal having a Young's modulus of 100 GPa or more and / or a thermal expansion coefficient difference of 2 × 10 ⁻⁶ / K or more with the base steel plate and having an average crystallite size of 10 nm or more in a weight ratio of 10. % Or more and the average particle size of the crystal particles is 1
A low iron loss grain-oriented electrical steel sheet having a coating film having a thickness of 000 nm or less and a thickness of 0.2 μm or more and 5 μm or less formed on the surface. 2. A crystal having a Young's modulus of 100 GPa or more and / or a difference in thermal expansion coefficient of 2 × 10 ⁻⁶ / K or more with the base steel sheet and having an average crystallite size of 10 nm or more in a weight ratio of 10. % Or more and less than 95%, and crystals of 5% or more and less than 90% which do not meet the above requirements and are formed by the reaction of the above-mentioned crystals with other coating film constituent components and / or base steel plate components, and the average of the constituent crystal particles A coating with a particle size of 1000 nm or less is 0.2 μm or more and 5 μm
A low iron loss grain-oriented electrical steel sheet formed on the surface with the following thickness. 3. A crystal having an average crystallite size of 10 nm or more in a weight ratio of 10% to less than 95%, and an amorphous phase formed as a result of melting mainly in a baking step of 5% to 90%.
%, And the average particle size of the crystalline particles is 100.
The low iron loss grain oriented electrical steel sheet according to claim 2, wherein the coating film having a thickness of 0 nm or less is formed on the surface with a thickness of 0.2 µm or more and 5 µm or less. 4. A crystal having a Young's modulus of 100 GPa or more or a difference in thermal expansion coefficient of 2 × 10 ⁻⁶ / K or more from a base steel sheet is Li, B, Mg, Al, Si, P, Ti, V, Mn. ，
The low iron loss grain-oriented electrical steel sheet according to claim 1, which is one or more compounds containing at least one of Fe, Co, Ni, Cu, Zr, Sn, and Ba as a component. 5. The low iron loss grain-oriented electrical steel sheet according to claim 3, wherein the amorphous phase formed as a result of melting mainly in the baking step is a glass phase containing B and P as one component. 6. A crystal having a Young's modulus of 100 GPa or more or a coefficient of thermal expansion difference of 2 × 10 ⁻⁶ / K or more with a base steel sheet is aluminum borate, and the amorphous phase has B as one component. The low iron loss grain-oriented electrical steel sheet according to claim 3, which is a glass phase.