JPH07310188A - Separation agent for annealing grain-oriented silicon steel sheet excellent in reactivity and method for using the same - Google Patents

Abstract

PURPOSE:To improve a glass film in a grain-oriented silicon steel sheet and to obtain good magnetic properties. CONSTITUTION:A steel sheet after decarburizing annealing is coated with solid solution-type multiple metal oxide as separation agent for annealing for a grain- oriented silicon steel sheet shown by general fomulae of [Mg1-xM<3+>x]O, [Mg1-xM<2+>x]O and [Mg1-xM<2+>x1M<3+>x2] and is subjected to finish annealing, by which grain-oriented silicon steel sheet extremely excellent in the glass film and magnetic properties can be obtd. In the formulae, M<2+> denotes the bivalent metals such as Be, Ca, Ba, Sr, Sn, Mn, Fe, Co, Ni, Cu, Zn or the like, M<3+> denotes the trivalent metals such as Al, Fe, Cr, Co, Ni, Cu, Zn or the like, and 0.01<=x<=0.40 and x=x1+x2 are regulated. A part of Mg in MgO is substitutionally entered solid solutio by the bivalent metals, trivalent metals or by both, its m.p. is changed into a lower one by the multiple metal oxide, and a glass film is formed from a low temp. in a finish annealing temp. rising stage, by which the uniform glass film having high tensile strength can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an annealing separator for producing a grain-oriented electrical steel sheet and a method of using the grain-oriented electrical steel sheet which has a uniform and extremely excellent glass coating and at the same time has excellent magnetic properties. Regarding

[0002]

2. Description of the Related Art Usually, grain-oriented electrical steel sheets are obtained by hot rolling a material containing Si: 4% or less, and annealing it once or two times.
The final plate thickness is obtained by cold rolling more than once. Then N ₂
Decarburization annealing is performed by controlling P H ₂ O / P H ₂ in an atmosphere gas such as + H ₂ or H ₂ to perform primary recrystallization, decarburization, and formation of an oxide film containing SiO ₂ as a main component. . After that, an annealing separator containing MgO as a main component is made into a slurry and applied by a coating roll or the like, and final annealing is performed.
After secondary recrystallization, purification, and glass film formation, a tension-imparting insulating film agent is usually applied, and baking treatment is performed in a continuous line to obtain a product. Further, in the case of a high magnetic flux density grain-oriented electrical steel sheet, particularly in the case of a thin agent having a sheet thickness of 0.17 mm or less, a magnetic domain subdivision treatment for imparting linear flaws is performed by a laser, a press roll, a tooth mold roll, a scribe, etc. The iron loss is improved.

This grain-oriented electrical steel sheet utilizes the phenomenon that (110) <001> crystals having a <001> axis grow preferentially in high temperature finish annealing (secondary recrystallization annealing). This secondary recrystallization process has a low surface energy (110)
The face crystals grow preferentially, and in order to erode other crystals whose growth is suppressed by AlN, MnS, etc. finely dispersed as inhibitors in the steel, (110) <00
1> It is believed that crystals grow preferentially. Therefore, in order to manufacture an excellent grain-oriented electrical steel sheet, it is important to control the dispersion of AlN, MnS, etc. in the steel and the control until their decomposition.

The change in inhibitor during final annealing is
It is known that it is affected by the oxide film formed by decarburization annealing, the annealing separator, the thermal cycle of final finishing annealing, and the atmospheric conditions. Among these, the annealing separator M
The properties of gO and additives have a great influence on the glass film formation start time, formation rate, film quality, amount, etc., and therefore have a great influence on the inhibitor.

The annealing separator MgO reacts with the SiO ₂ -based oxide film formed by decarburization annealing to form a forsterite-based glass film usually called a glass film (2).
MgO + SiO ₂ → Mg ₂ SiO ₄ ). In forming the glass film, when a conventional MgO powder is used, Mg is not used because of the problem of reactivity control in forming the glass film.
As properties of O, in particular, particle size, purity, activity, as well as dispersibility at the time of application to a steel sheet, hydration amount, application amount, uniformity of coating film, adhesion to steel sheet surface, etc. The type and amount of the additive added as a reaction accelerator for forming the glass film and the state of dispersion on the MgO surface and the steel sheet surface affect the film formation start temperature, the formation rate, the formation amount, and the like. These differences in various MgO characteristics in the annealing separator have the result that not only the coating characteristics of the final product but also the magnetic characteristics are influenced.

The MgO used as the annealing separator is generally prepared by adjusting raw materials such as magnesium hydroxide, magnesium carbonate and basic magnesium carbonate into fine particle crystals having an average particle size of several hundred to several thousand angstroms. , 7
0.2 to 5 μm after firing at a high temperature of about 00 to 1200 ° C.
It is used by obtaining fine crystalline particles of MgO of a certain degree. Usually, this MgO is mixed with various additives as a reaction accelerator at the time of glass formation, if necessary, and suspended in water to form a slurry, which is then stored in a tank equipped with a stirrer such as a propeller or shear. After stirring and dispersing, the surface of the steel sheet is coated with a rubber roll or the like and dried.

At this time, MgO and additives are agglomerated due to a change with time due to moisture absorption during storage from sintering or firing in the production stage to the use stage, or a strong agglomeration reaction between particles in a stage of suspension in water. Therefore, at the stage of being applied to the steel plate surface,
It becomes coarse particles of several microns to several tens of microns and causes a decrease in reactivity. In particular, in the case of conventional MgO, in order to obtain low-hydrated MgO, it is necessary to manufacture it by high temperature firing, and in such a case, the reaction such as sintering and aggregation of MgO is further strengthened. For this reason, on the surface of the steel sheet after coating and drying, the contact area of MgO particles is reduced, the coating film density is reduced, the adhesion to the steel sheet surface is reduced, and the uniformity of the coating film is reduced.

Further, in such a case, the viscosity of the slurry is lowered, the workability at high speed is deteriorated, and uniform coating becomes very difficult. When MgO is mixed with an additive as a reaction accelerator for the glass film, the additive itself remains in the coating film or steel plate oxidation as coarse particles that cause sintering during production or aggregation in the slurry. Present on the membrane.
This phenomenon becomes even more noticeable when MgO is added to MgO, which has a strong cohesive property. As a result, the reaction accelerating effect is weakened or a non-uniform reaction occurs, making it difficult to obtain a uniform and good glass film, which causes deterioration of magnetic properties. Due to these problems, development of an annealing separator having good dispersibility, fine particles and good reactivity is an important issue.

As a technique for producing an annealing separator MgO having excellent reactivity, JP-A-62-156226 proposes a method of activating the outermost surface layer of MgO particles by the present inventors. In this method, only the outermost surface layer of MgO particles obtained by high-temperature calcination has a hydration layer M at the MgO production stage.
Forming g (OH) ₂ , the uniformity of the glass coating is improved and the effect of improving the magnetic properties is obtained. Further, in Japanese Patent Application Laid-Open No. 2-267278, 10
Decarburization annealing of an annealing separator containing MgO, which is formed by passing through an atmosphere containing water vapor at 0 ° C. or higher and forming an OH chemisorption layer on the MgO surface in an amount of 0.8 to 2.5% based on the amount of MgO in terms of H ₂ O. A technique has been proposed since it is applied to a subsequent steel sheet and finish annealing is performed. It is stated that this makes it possible to obtain a grain-oriented electrical steel sheet having a uniform glass coating and excellent magnetic properties.

Japanese Unexamined Patent Publication (Kokai) No. 5-247661 discloses a method for producing a grain-oriented electrical steel sheet having a uniform glass coating and excellent magnetic properties, in which a certain amount of SiO ₂ is used in a decarburizing annealing step.
There has been proposed a method of forming a layer and performing ultrafine atomization of a slurry and activation treatment of a particle surface by a slurry fine particle dispersion device when applying an annealing separator slurry. In all of these techniques, as a solution to the agglomeration of MgO particles at the time of applying an annealing separator, the MgO surface after annealing is subjected to a special surface treatment at high temperature to be modified, or atomized by an ultrafine dispersion technique. And surface modification, which lowers the surface energy and improves the compatibility with water, and at the same time MgO
The forsterite formation reaction is improved by the fixed amount of OH layer formed on the surface layer of the particles. Due to this effect, it is applied on the surface of the steel sheet in a state of better dispersion than that of conventional MgO, and a considerable improvement effect in glass film formation is obtained.

However, the problems caused by the MgO production conditions such as sintering, stability of the OH chemisorption layer, and agglomeration due to changes with time from MgO production to use have not been completely solved, and they are formed during decarburization annealing. Depending on the quality of the oxide film formed, there remains a problem that problems with the film and magnetic properties cannot be avoided. Therefore, further development and improvement of MgO having lower hydration and higher reactivity are desired.

[0012]

DISCLOSURE OF THE INVENTION In the present invention, when applying an annealing separator during the production of grain-oriented electrical steel sheet, the problems of the conventional method of improving the reactivity and lowering the melting point of MgO in forming a glass coating film are solved by a novel annealing. A solution is applied by applying a separating agent.

At this time, as the MgO, a composite MgO compound in which a part of the Mg element of MgO is replaced with another divalent or trivalent metal at the time of production to form a solid solution is used. A melting point is obtained, and improvement is aimed at by lowering the temperature of the glass film formation during finish annealing and making it uniform and stable. As a result, the film has good tension, adhesion, uniformity, and the like, and at the same time obtains the effect of sealing the surface by the film,
The purpose is to provide an annealing separator and a method of using the same for obtaining the stabilization of the inhibitor and at the same time obtaining good magnetic properties.

[0014]

The present inventors have manufactured a product having a uniform glass coating and excellent magnetic properties in the glass coating forming process from the decarburization annealing to the final finish annealing of the grain-oriented electrical steel sheet. I examined the method. In this research, the research was conducted with a particular focus on improving the reactivity of MgO used as an annealing separator. As an annealing separator,
Usually, MgO and an additive such as a Ti compound as a reaction accelerator are used. In such a conventional technique, Mg
Only the nature of O affects the glass film formation, mainly the reactivity and stability of the film, and not only the film, but also the magnetic properties are greatly affected, so the auxiliary effect of the additive is rather important. Is.

The present inventors conducted extensive research and experiments on the formation of solid solution type composite metal oxides of MgO as a novel low hydration highly reactive annealing separator. As a result, a solid solution type composite Mg in which a divalent or trivalent metal element is substituted for a part of MgO is used as a novel annealing separator capable of solving the above problems.
A new composition material based on O has been developed. As a result, the melting point of the MgO substance in the grain-oriented electrical steel sheet production was significantly lowered, and the glass coating formation temperature was significantly lowered and the reaction was stabilized uniformly. As a result, we have developed a technology that can form a remarkable glass film under a wide range of oxide film formation conditions during decarburization annealing, and can achieve a significant magnetic improvement effect due to the film sealing effect and tension increasing effect. is there.

Next, the novel solid solution type composite M in the present invention
A typical method for producing a gO compound and reasons for improving reactivity will be described.

The solid solution type composite MgO compound of the present invention is [Mg
_1-x M ³⁺ _x ] O, [Mg _1-x M ²⁺ _x ] O, [Mg _1-x M
²⁺ _x1 M ³⁺ _x2 ] O solid solution type complex oxide represented by the general formula M ²⁺ ; Be, Ca, Ba, Sr, Sn, Mn, Fe, C
o, Ni, Cu, Zn and other divalent metals M ³⁺ ; Al, Fe, Cr, Co, B, Ti and Sb and other trivalent metals 0.01 ≦ x ≦ 0.40 x = x1 + x2. In the production of this composite oxide, for example, first, as a crystal structure, a layered structure comprising a positively charged basic layer similar to brucite [Mg (OH) ₂ ] and a negatively charged intermediate layer composed of anions and interlayer water. Build.
In this case, the positive charge amount is determined depending on the substitution amount. This positive charge is neutralized by the anion of the intermediate layer to maintain electrical neutralization of the crystal as a whole.

The remaining space occupied by the anions in the intermediate layer is filled with interlayer water. This composite metal hydroxide is produced, for example, by using M ²⁺ , M ³⁺ and A ⁿ⁻ (OH ⁻ , F ⁻ , C.
l ⁻ , Br ⁻ , CO ₃ ⁻ , SO ₄ ⁻ , SiO ₃ ⁻ , HP
O ₄ ²⁻ , CrO ₄ ²⁻ , Fe (CN) ₆ ^3−, etc.) is added to the mixture, and the reaction is performed while keeping the pH at 7 or higher. This complex metal hydroxide material is then
700-1000 in rotary kiln, batch type furnace, etc.
A composite metal oxide is obtained by firing at a high temperature of about 0 ° C. while controlling the temperature and time.

In the composite metal oxide produced in this manner, the effect of lowering the melting point of the solid solution substance and the effect of the anion substance added as necessary act synergistically, and the conventional MgO simple substance oxide is used. The high reactivity and the effect of lowering the melting point, which cannot be obtained by the substance or the oxide mixture substance, can be obtained. Therefore, during finish annealing, the glass film formation temperature starts on the extremely low temperature side and
Destabilization of N, MnS, etc. is prevented, and the deinhibitor phenomenon due to a tight and uniform glassy coating is suppressed even at the high temperature stage of the initiation of secondary recrystallization, and a crystal structure having a good orientation can be obtained. Further, the glass film to be finally formed is also uniform and has high adhesion and high tensile strength, and an extremely good iron loss characteristic can be obtained by the synergistic effect with the increase in magnetic flux density.

Next, the reasons for limitation of the present invention will be described.
The present invention relates to a novel annealing separator applied when applying an annealing separator on the surface of a steel sheet after decarburization annealing in the production of grain-oriented electrical steel. The summary is as follows. (1) [Mg _1-x M ³⁺ _x ] O, [Mg _1-x M ²⁺ _x ] O,
[Mg _1-x M ²⁺ _1x M ³⁺ _{x 2} ] O 1 or a mixture of two or more solid solution type complex metal oxides represented by the general formula Annealing separator for grain oriented electrical steel. M ²⁺ ; Be, Ca, Ba, Sr, Sn, Mn, Fe, C
o, Ni, Cu, Zn and other divalent metals M ³⁺ ; Al, Fe, Cr, Co, B, Ti and Sb and other trivalent metals 0.01 ≦ x ≦ 0.40 x = x1 + x2

(2) The material for grain-oriented electrical steel sheets is cold-rolled to the final thickness and then decarburized and annealed to form an oxide film mainly composed of SiO ₂ on the surface, and an annealing separator containing MgO as a main component. Is applied, finish annealing is performed, and the insulating coating agent is treated and baked.
_1-x M ³⁺ _x ] O, [Mg _1-x M ²⁺ _x ] O, [Mg _1-x M
²⁺ _x1 M ³⁺ _x2 ] O One or a mixture of two or more solid solution type complex metal oxides represented by the general formula, is applied to a steel sheet, and the directionality is extremely excellent. How to use an annealing separator for electrical steel. M ²⁺ ; Be, Ca, Ba, Sr, Sn, Mn, Fe, C
o, Ni, Cu, Zn and other divalent metals M ³⁺ ; Al, Fe, Cr, Co, B, Ti and Sb and other trivalent metals 0.01 ≦ x ≦ 0.40 x = x1 + x2

(3) As an annealing separator in the method described in (2), as a reaction promoting auxiliary agent for forming a glass film, one selected from sulfate, sulfide, borate, chloride and oxide, or A method for using an annealing separator for an electromagnetic steel sheet, which comprises adding 0.01 to 10 parts by weight to 100 parts by weight of solid solution type composite MgO.

The most characteristic of the present invention is a solid solution type composite metal oxide in which a part of Mg of MgO used as an annealing separator is replaced with another metal element. Can be obtained. The form of the oxide is [Mg _1-x M ³⁺ _x ] O, [Mg _1-x M ²⁺ _x ] O, [M
g _1-x M ²⁺ _x1 M ³⁺ _x2 ] O is a solid solution type complex metal oxide represented by the general formula. That is, a part of the Mg metal element is replaced with a divalent metal, a divalent or trivalent metal, or a trivalent metal to form a solid solution. The divalency at this time,
As the trivalent substituted metal element, M ²⁺ ; Be, Ca, Ba, Sr, Sn, Mn, Fe, C
o, Ni, Cu, Zn and other divalent metals M ³⁺ ; Al, Fe, Cr, Co, B, Ti and Sb and other trivalent metals 0.01 ≦ x ≦ 0.40 x = x1 + x2. The divalent or trivalent metal solid solution type complex oxide in the present invention also includes a complex metal oxide in a form in which MgO contains a plurality of two or more of these elements.

The substitution metal elements to be applied are the above-mentioned metal elements, respectively, and MgO serving as a base in the composite metal oxide substance obtained by substituting these metal elements.
A significantly lower melting point can be obtained compared to a single substance. MgO
The amount of the other metal substance replaced by
The range is 0.40. If it is less than 0.01, the effect of lowering the melting point cannot be obtained, and the effect of improving the glass coating and magnetism cannot be obtained. On the other hand, when it is 0.40 or more, an appropriate lowering of the melting point cannot be obtained, or a peroxide-like film defect occurs, which is not preferable. The most preferable range is 0.03 to 0.25. Moreover, the ratio of the substitutional solid solution metal in the case of combining divalent and trivalent metals is not particularly limited as long as it is in the range of 0.01 to 0.4.

Next, when the composite metal oxide of the present invention is applied as an annealing separator for grain-oriented electrical steel sheets, sulfates, sulfides, etc. are added as reaction accelerating aids for glass coatings depending on the steel sheet composition and sheet thickness. One or more selected from borate, chloride, oxide and the like can be used in a ratio of 0.01 to 10 parts by weight per 100 parts by weight of the composite metal oxide.
If it is less than 0.01%, the reaction promoting effect is weak. On the other hand, 1
When it is 0 parts by weight or more, it is a pinhole shape peculiar to the peroxide reaction,
It is not preferable because scale-like and gas-mark-like defects occur.

In the solid solution type composite metal oxide of the present invention, the effect is considerably smaller than the conventional role of the additive in MgO. However, if appropriate additives and amounts are selected, it is possible to obtain a stable auxiliary effect of improving reactivity by matching the high reactivity of the composite metal oxide itself, and to obtain a stable reaction from dry to wet under atmospheric conditions during finish annealing. It is possible to improve the sex.

[0027]

【Example】

Example 1 C: 0.050% by weight, Si: 3.1
5%, Mn; 0.063%, S; 0.024%, Al;
A grain-oriented electrical steel sheet material consisting of 0.007% and the balance unavoidable impurities and Fe was cold-rolled once or twice with hot rolling and annealing sandwiched by a known method to give a final sheet thickness of 0.34 mm.
After that, decarburization annealing is performed in a humid atmosphere gas of N ₂ 25% + H ₂ 75%, decarburization and an oxide layer mainly composed of SiO ₂ are formed on the surface, and annealing of the composite metal oxide composition having the composition shown in Table 1 is performed. 15g / m ² (7.5g on one side) of separating agent is applied and after drying 20T
The coil was wound and the final annealing was performed at 1200 ° C. × 20 Hr. After this, 20% colloidal silica 100 ml-50%
The insulating coating agent consisting of phosphoric acid Al 50ml-CrO ₃ 6g was applied and subjected to baking treatment with the heat flattening at 850 ° C.. Table 2 shows the state of formation of the glass film after the finish annealing and the film properties after the insulating film treatment and baking in this test.

[0028]

[Table 1]

[0029]

[Table 2]

As a result of this experiment, in all of the present invention, a uniform, thick and glossy glass film was formed over the entire surface of the steel sheet, and the adhesion of the film after the insulating film treatment was good. On the other hand, when ordinary MgO was used as the annealing separator of the comparative material, gas mark-like unevenness was generated at the edge portion of the steel sheet, and the adhesion was inferior to that of the present invention. Regarding the magnetic properties, the magnetic properties according to the present invention were stable and good, and the iron loss also showed a very good value, whereas the comparative material was considerably inferior.

[Example 2] C by weight%: 0.075%,
Si; 3.25%, Mn; 0.075%, S; 0.02
5%, Cu; 0.010%, Sn; 0.08%, Al;
0.026%, N; 0.0080 The balance is a high magnetic flux density grain-oriented electrical steel sheet material slab consisting of inevitable impurities and Fe by hot rolling-annealing-pickling-cold rolling to a final sheet thickness of 0. 225 mm. This steel sheet is N ₂ 5% + H ₂ 75
%, Decarburization annealing was performed in a humid atmosphere gas having a dew point of 65 ° C. Then, an annealing separator having a composition shown in Table 3 and containing a composite metal oxide as a main component was applied so as to have a dry weight of 12 g / m ² , followed by final finishing annealing at 1200 ° C. × 20 Hr. . Thereafter, a coating agent having the same composition as that of Example 1 was applied as an insulating coating agent so that the weight after drying-baking would be 5 g / m ² , and heat flattening and baking treatment were performed at a furnace temperature of 850 ° C. Table 4 shows the results of the coating properties and magnetic properties at this time.

[0032]

[Table 3]

[0033]

[Table 4]

As a result, in all of the composite metal oxides of the present invention used as the annealing separator, the glass coating was uniformly formed over the entire surface of the steel sheet, and the glass coating had good tension and adhesion. As for the magnetic characteristics, the magnetic flux density and iron loss characteristics of the present invention were all very good. On the other hand, when the conventional MgO of the comparative example was applied, the coating properties and magnetic properties were considerably inferior to those of the present invention.

[Example 3] C by weight%: 0.060%,
Si; 3.30%, Mn; 1.05%, S; 0.008
%, Al; 0.030%, N; 0.0080%, Sn;
A raw material consisting of 0.03% and the balance of inevitable impurities and Fe was slab-heated at a low temperature of 1250 ° C., hot-rolled sheet annealed, and pickled cold-rolled to a thickness of 0.225 mm. Then N
₂ 25% + H ₂ 75%, decarburization annealing in an atmosphere gas with a dew point of 65 ° C, decarburization and forming a SiO ₂ film on the surface, and subsequently 750 ° C x 3 in a dry atmosphere zone provided on the same line
The sample was prepared by performing a nitriding treatment in an atmosphere of N ₂ 25% + H ₂ 75% + NH ₃ for 0 seconds so that the total N content of the steel sheet was 200 ppm. An annealing separator having a composition of a composite metal oxide having a composition as shown in Table 5 was added to the steel sheet at a weight of 12 g after drying.
/ M ² and then dried and then subjected to finish annealing and insulating film treatment in the same manner as in Examples 1 and 2. The results of the glass coating properties and magnetic properties are shown in Table 6.

[0036]

[Table 5]

[0037]

[Table 6]

As a result, according to the present invention, the glass coating was formed extremely uniformly, a product having a very high glass coating tension was obtained, and the adhesion was stable. Also, the magnetic properties were extremely good results that could not be obtained by the conventional annealing separator. On the other hand, the comparative material has more complex metal substances than the present invention, and the comparative example 1 has many shimofuri and gas-mark-like coating defects as seen in the case of excessive oxidation, and the conventional MgO. Comparative Example 2 by
There were many poorly formed glass coatings, which were uneven and thin, and the coating tension was small.

FIG. 1 shows a glass coating when (A) the composite metal oxide of the present invention (Invention 4) is used and (B) the conventional MgO (Comparative Example 1) is used as an annealing separator. It is the result of analyzing the formation reaction in the finish annealing process. As for the activity of the Mg substance as the annealing separator, the CAA value (measured at 30 ° C.) was adjusted to 45 seconds and used.

As shown in the figure, it was confirmed that the glass according to the present invention formed a glass film at a lower temperature in the final annealing temperature rising process, and the final formation amount was larger than that of the comparative material. Also, the magnetic properties were considerably inferior to the material of the present invention.

[0041]

INDUSTRIAL APPLICABILITY The present invention uses Mg as a novel annealing separator.
Substitution of a part of Mg in O with another divalent or trivalent metal to obtain a low melting point and a reaction promoting effect by a solid solution mixed metal oxide,
A uniform and high-tensile glass film is formed, and the excellent sealing effect on the surface of the steel sheet during the film formation process and the deinhibitor process prevents the deterioration and weakening of the inhibitor and allows good secondary recrystallization. , Extremely excellent magnetic characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a chart showing the state of glass film formation in the final annealing temperature rising process when the annealing separator of Example 2 is used.

Continuation of the front page (72) Inventor Tomoji Kumano 1-1 Hibahata-cho, Tobata-ku, Kitakyushu City Shin Nippon Steel Yawata Works Co., Ltd.

Claims (3)

[Claims] 1. [Mg _1-x M ³⁺ _x ] O, [Mg _1-x M ²⁺
_x ] O, [Mg _1-x M ²⁺ _x1 M ³⁺ _x2 ] O, which is one or a mixture of two or more solid solution type complex metal oxides represented by the general formula. An annealing separator for grain-oriented electrical steel sheets with extremely excellent properties. M ²⁺ ; Be, Ca, Ba, Sr, Sn, Mn, Fe, C
o, Ni, Cu, Zn and other divalent metals M ³⁺ ; Al, Fe, Cr, Co, B, Ti and Sb and other trivalent metals 0.01 ≦ x ≦ 0.40 x = x1 + x2 2. A material for a grain-oriented electrical steel sheet after cold rolling to a final thickness is decarburized and annealed to form an oxide film mainly composed of SiO ₂ on the surface, and an annealing separator containing MgO as a main component is applied. In a process consisting of coating, finish annealing, and treating and baking an insulating coating agent, [Mg
_1-x M ³⁺ _x ] O, [Mg _1-x M ²⁺ _x ] O, [Mg _1-x M
²⁺ _x1 M ³⁺ _x2 ] O, which is characterized by applying one or a mixture of two or more solid solution type complex metal oxides represented by the general formula on a steel sheet, which is extremely reactive. Of using annealing separator for high-strength electrical steel sheet. M ²⁺ ; Be, Ca, Ba, Sr, Sn, Mn, Fe, C
o, Ni, Cu, Zn and other divalent metals M ³⁺ ; Al, Fe, Cr, Co, B, Ti and Sb and other trivalent metals 0.01 ≦ x ≦ 0.40 x = x1 + x2 3. One or more selected from sulfates, sulfides, borates, chlorides, and oxides is 0.01 to 10 parts by weight with respect to 100 parts by weight of a solid solution type composite metal oxide. The method of using the annealing separator for an electromagnetic steel sheet according to claim 2, wherein the agent is added.