Annealing separating agent

Abstract

The present invention provides an annealing separation agent containing MgO, with a CaO content of 0.10 to 1.00 mass%, a Fe2O3 content of 0.01 to 0.50 mass%, an Al2O3 content of 0.01 to 0.50 mass%, a Cl content of 0.005 to 0.100 mass%, a F content of 0.001 to 0.100 mass%, a Na content of 0.0001 to 0.0100 mass%, a K content of 0.00001 to 0.01000 mass%, a SO3 content of 0.010 to 0.500 mass%, a SiO2 content of 0.01 to 1.00 mass%, and a B content of 0.001 to 1.00 mass%. The present invention provides an annealing separation agent that yields grain-oriented electrical steel sheets with excellent film adhesion.

Description

[Technical Field]

[0001] This invention relates to an annealing separating agent. [Background technology]

[0002] Grain-oriented electrical steel sheets are generally manufactured by hot-rolling and cold-rolling a steel slab having a predetermined composition, then subjecting the resulting steel sheet (cold-rolled sheet) to primary recrystallization annealing, followed by finish annealing including secondary recrystallization annealing.

[0003] Since finish annealing is often performed at high temperatures on rolled steel sheets (i.e., coils), there is a risk that overlapping steel sheets may bond together during the finish annealing process. Conventionally, in order to prevent adhesion of steel plates, an annealing separating agent (Patent Documents 1-2) containing magnesium oxide (MgO) as the main component is applied to the surface of the steel plate in a slurry state dispersed in water before the finish annealing.

[0004] On the surface of the steel sheet, an oxide layer containing silicon dioxide (SiO2) as the main component is formed by primary recrystallization annealing. In addition to the aforementioned role of preventing adhesion, the annealing separator also plays a role in forming a forsterite (Mg2SiO4) film called a forsterite coating by reacting with this oxide layer (SiO2). The forsterite coating also acts as a binder, ensuring that the insulating coating formed in a later process adheres firmly to the steel sheet. The insulating coating improves the magnetic properties of the grain-oriented electrical steel sheet by applying tension to the steel sheet. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2002-309378 [Patent Document 2] Japanese Patent Publication No. 2004-238668 [Overview of the Initiative] [Problems to be Solved by the Invention]

[0006] When the inventors of the present invention trial-produced a grain-oriented electrical steel sheet using a conventional annealing separator, there were cases where a trial product with insufficient adhesion of the forsterite film to the steel sheet (hereinafter also referred to as "film adhesion") was obtained.

[0007] The present invention has been made in view of the above points, and an object thereof is to provide an annealing separator capable of obtaining a grain-oriented electrical steel sheet having excellent film adhesion. [Means for Solving the Problems]

[0008] In order to achieve the above object, the inventors of the present invention earnestly studied, paying attention to the influence of various elements contained in the annealing separator. As a result, they found that good film adhesion can be obtained by setting the content of various elements within a specific range, and completed the present invention. That is, the present invention provides the following [1] to [5]. [1] An annealing separator containing MgO, having a CaO content of 0.10 to 1.00% by mass, an Fe2O3 content of 0.01 to 0.50% by mass, an Al2O3 content of 0.01 to 0.50% by mass, a Cl content of 0.005 to 0.100% by mass, an F content of 0.001 to 0.100% by mass, a Na content of 0.0001 to 0.0100% by mass, a K content of 0.00001 to 0.01000% by mass, a SO3 content of 0.010 to 0.500% by mass, a SiO2 content of 0.01 to 1.00% by mass, and a B content of 0.001 to 1.000% by mass. [2] M represented by the following formula (1) * is 1.30 to 1.70, and S represented by the following formula (2) * is 0.0300 to 0.0600, and F represented by the following formula (3) * is 0.40 to 0.60, and the annealing separator according to [1] above. M * = 3 × [CaO] + 2 × [Fe2O3] + [Al2O3] ··· (1) S *=[Cl] + 2×[F] + 5×[Na] + 5×[K] ··· (2) F * =[SiO2] + 5×[B] ··· (3) However, [A] in the above formulas (1) to (3) is the content of component A in mass% per unit mass. [3] M represented by the following formula (1) * is 1.30 to 1.70, and S represented by the following formula (2) * is 0.0300 to 0.0600, and F represented by the following formula (3) * is 0.40 to 0.60, and X represented by the following formula (4) * is 0.50 to 3.00, the annealing separation agent described in the above [1].[[]END]] M * = 3×[CaO] + 2×[Fe2O3] + [Al2O3] ··· (1) S * =[Cl] + 2×[F] + 5×[Na] + 5×[K] ··· (2) F * =[SiO2] + 5×[B] ··· (3) X * =(M * ×S * ) / ([SO3] × F * [[ID=3)) ··· (4) However, [A] in the above formulas (1) to (4) is the content of component A in mass% per unit mass. [4] The annealing separation agent according to any one of the above [1] to [3], wherein the crystallite diameter of MgO is 20 to 40 nm. [5] The annealing separation agent according to any one of the above [1] to [4], which is used in the production of a grain-oriented electrical steel sheet. [Advantages of the Invention]

[0009] [[ID=())) According to the present invention, an annealing separation agent capable of obtaining a grain-oriented electrical steel sheet excellent in film adhesion can be provided. [Embodiments for Carrying Out the Invention]

[0010] [Annealing Separation Agent] The annealing separation agent of the present embodiment contains MgO and further has a component composition described later. The grain-oriented electrical steel sheets manufactured using the annealing separating agent of this embodiment exhibit excellent adhesion (coating adhesion) between the steel sheet and the forsterite coating. The shape of the annealing separating agent in this embodiment is not particularly limited and may be, for example, in powder form. The annealing separating agent of this embodiment will be described in more detail below.

[0011] <Component composition> First, let's explain the component composition of the annealing separating agent. In the component composition of annealing separation agents, "%" refers to "mass%" unless otherwise specified. The content of each component (element) is determined in accordance with JIS R 1688:2010.

[0012] CaO: 0.10-1.00% Ca is an effective element for improving film adhesion by increasing the reactivity of MgO, thereby promoting the formation of forsterite coatings. On the other hand, if there is too much Ca, the reactivity of MgO increases excessively, causing the forsterite coating to develop excessively, which actually reduces the adhesion of the coating. Therefore, the Ca content (i.e., CaO content) in terms of oxide (CaO) is 0.10 to 1.00%, preferably 0.20 to 0.60%, and more preferably 0.30 to 0.50%.

[0013] 《Fe2O3: 0.01~0.50%》 Like Ca, Fe is an effective element for improving film adhesion by increasing the reactivity of MgO, thereby promoting the formation of forsterite coatings. On the other hand, if there is too much Fe, the reactivity of MgO increases excessively, causing the forsterite coating to develop excessively, which actually reduces the adhesion of the coating. Therefore, the Fe content (i.e., Fe2O3 content) in terms of oxide (Fe2O3) is 0.01 to 0.50%, preferably 0.03 to 0.20%, and more preferably 0.05 to 0.15%.

[0014] Al2O3: 0.01-0.50% Al, like Ca, is an effective element for improving film adhesion by increasing the reactivity of MgO, thereby promoting the formation of forsterite coatings. On the other hand, if there is too much Al, the reactivity of MgO becomes excessively high, causing the forsterite coating to develop excessively, which actually reduces the adhesion of the coating. Therefore, the Al content (i.e., Al2O3 content) in terms of oxide (Al2O3) is 0.01 to 0.50%, preferably 0.02 to 0.10%, and more preferably 0.03 to 0.05%.

[0015] 《Cl:0.005~0.100%》 Cl is an effective element for improving film adhesion by increasing the reactivity of subscales, thereby promoting the formation of forsterite coatings. On the other hand, if there is too much Cl, the reactivity of the subscale increases excessively, causing the forsterite film to develop excessively, which in turn reduces film adhesion. Therefore, the Cl content is 0.005 to 0.100%, preferably 0.007 to 0.040%, and more preferably 0.010 to 0.030%.

[0016] 《F:0.001~0.100%》 Like Cl, F is an effective element for improving film adhesion by increasing the reactivity of subscales, thereby promoting the formation of forsterite films. On the other hand, if there is too much F, the reactivity of the subscale increases excessively, causing the forsterite film to develop excessively, which actually reduces film adhesion. Therefore, the F content is 0.001 to 0.100%, preferably 0.003 to 0.020%, and more preferably 0.005 to 0.015%.

[0017] 《Na: 0.0001~0.0100%》 Like Cl, Na is an effective element for improving film adhesion by increasing the reactivity of subscales, thereby promoting the formation of forsterite coatings. On the other hand, if there is too much Na, the reactivity of the subscale increases excessively, causing the forsterite film to develop excessively, which in turn reduces film adhesion. Therefore, the Na content is preferably 0.0001 to 0.0100%, more preferably 0.0005 to 0.0050%, and more preferably 0.0010 to 0.0030%.

[0018] 《K:0.00001~0.01000%》 Like Cl, K is an effective element for improving film adhesion by increasing the reactivity of subscales, thereby promoting the formation of forsterite films. On the other hand, if there is too much potassium, the reactivity of the subscale increases excessively, causing the forsterite film to develop excessively, which in turn reduces film adhesion. Therefore, the K content is preferably 0.00001 to 0.01000%, more preferably 0.00005 to 0.00100%, and more preferably 0.00010 to 0.00050%.

[0019] 《SO3: 0.010~0.500%》 S is an effective element for improving coating adhesion by increasing the reactivity of steel sheets, thereby promoting the formation of forsterite coatings. On the other hand, if there is too much sulfur, the reactivity of the steel sheet increases excessively, causing the forsterite coating to develop excessively, which in turn reduces the adhesion of the coating. Therefore, the sulfur content (i.e., SO3 content) in terms of oxides (SO3) is 0.010 to 0.500%, preferably 0.030 to 0.200%, and more preferably 0.050 to 0.150%.

[0020] 《SiO2: 0.01~1.00%》 Si is an effective element for improving film adhesion by promoting the formation of forsterite. On the other hand, if there is too much Si, forsterite formation is excessively promoted, the forsterite film develops excessively, and the adhesion of the film actually decreases. Therefore, the Si content (i.e., SiO2 content) in terms of oxide (SiO2) is 0.01 to 1.00%, preferably 0.03 to 0.30%, and more preferably 0.05 to 0.15%.

[0021] 《B: 0.001~1.000%》 Like Si, B is an effective element for improving coating adhesion by promoting the formation of forsterite. On the other hand, if there is too much B, forsterite formation is excessively promoted, the forsterite film develops excessively, and the adhesion of the film actually decreases. Therefore, the B content is 0.001 to 1.000%, preferably 0.030 to 0.200%, and more preferably 0.050 to 0.100%.

[0022] Other elements The annealing separating agent may further contain at least one element selected from the group consisting of C, N, P, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, and REM (excluding Y) (referred to as "other elements"). Incidentally, in grain-oriented electrical steel sheets, the insulating coating formed on the forsterite coating transmits light, so the appearance of the grain-oriented electrical steel sheet is determined by the appearance of the forsterite coating (hereinafter also referred to as "coating appearance"). If other elements are present in excessive amounts, a good coating appearance may not be obtained. For this reason, the content of each other element is preferably 0.1% or less.

[0023] 《MgO》 The MgO content may be, for example, 50.00% or more, 75.00% or more, or 90.00% or more. For superior film adhesion, the MgO content is preferably 95.00 to 99.90%, more preferably 96.00 to 99.70%, and even more preferably 97.00 to 99.50% or less. In the annealing separating agent, the remainder other than the components mentioned above may all be MgO.

[0024] <Component Parameters> The annealing separating agent of this embodiment can form a forsterite coating with excellent coating adhesion by satisfying the above-described range of component composition, and furthermore, the component parameter M described later... * S * and F * It is preferable that the following specific range is met. This results in better film adhesion.

[0025] 《M * :1.30~1.70》 M is represented by the following formula (1) * The ratio is preferably 1.30 to 1.70 or less, and more preferably 1.40 to 1.60. This allows for proper control of the reactivity of MgO and the formation of the forsterite film, resulting in superior film adhesion.

[0026] M * =3×[CaO]+2×[Fe2O3]+[Al2O3]···(1) In formula (1), [CaO], [Fe2O3], and [Al2O3] represent the CaO content, Fe2O3 content, and Al2O3 content, respectively, in the annealing separating agent (all in units of mass%).

[0027] 《S * :0.0300~0.0600》 S is represented by the following formula (2) * The ratio is preferably 0.0300 to 0.0600, and more preferably 0.0400 to 0.0500. This allows for proper control of the reactivity of the subscale and the formation of the forsterite film, resulting in superior film adhesion.

[0028] S * =[Cl]+2×[F]+5×[Na]+5×[K]...(2) In formula (2), [Cl], [F], [Na], and [K] represent the Cl content, F content, Na content, and K content (all in mass %) of the annealing separating agent, respectively.

[0029] 《F * :0.40~0.60》 F is represented by the following formula (3) * The ratio is preferably 0.40 to 0.60, and more preferably 0.45 to 0.55. This allows for proper control of the forsterite formation rate and the formation of the forsterite coating, resulting in superior coating adhesion.

[0030] F * =[SiO2]+5×[B]···(3) In formula (3), [SiO2] and [B] represent the SiO2 content and B content (both in mass%) of the annealing separation agent, respectively.

[0031] 《X * :0.50~3.00》 In the annealing separating agent of this embodiment, the component parameter X is represented by the following formula (4). * The ratio is preferably 0.50 to 3.00, more preferably 0.80 to 2.70, and even more preferably 1.20 to 2.30. This results in an excellent coating appearance. This is because it allows for the optimization of the balance between the three elements involved in the formation of forsterite precursors (hereinafter simply referred to as "precursors"): the reactivity of MgO, the reactivity of the subscale, and the reactivity of the steel sheet. In other words, the formation state of the precursor can be optimized, the balance between the precursor formation rate and the forsterite formation rate can be optimized, and the forsterite film formation reaction can be properly controlled.

[0032] Specifically, X * By ensuring that the size is not too small, it is possible to prevent the formation of forsterite coatings locally and thus prevent the generation of localized defects in the forsterite coatings. Meanwhile, X * By ensuring that the size is not too small, it is possible to prevent the forsterite film formation rate from becoming excessively fast, thereby preventing variations in forsterite film formation from place to place and preventing the formation of patterns on the forsterite film.

[0033] X * =(M * ×S * ) / ([SO3]×F * )···(4) M in equation (4) * S * and F * As stated above, [SO3] refers to the SO3 content (in mass %) in the annealing separating agent.

[0034] <Cryslite size of MgO: 20-40 nm> In the annealing separating agent of this embodiment, the crystallite size of MgO is not particularly limited, but 20 to 40 nm is preferred, and 25 to 35 nm is more preferred, for the reason that it provides a good film appearance. Specifically, by ensuring that the crystallite size of MgO is not too small, variations in forsterite film formation from location to location can be prevented, thus preventing the formation of patterns on the forsterite film. On the other hand, by keeping the crystallite size of MgO from being too large, it is possible to prevent the formation of forsterite coatings locally and thus prevent the generation of local defects in the forsterite coatings.

[0035] The crystallite size of MgO is determined as follows. First, the powder of the annealing separation agent to be measured is subjected to θ-2θ measurement using a powder X-ray diffractometer to obtain a diffraction profile. The measurement conditions are: X-ray output: 45kV, 200mA, scan speed: 0.5 degrees / min, step size: 0.02 degrees, and CuKα X-rays are used. Next, based on the obtained diffraction profile, the crystallite size of MgO is determined from the full width at half maximum (FMAX) of the (200) diffraction peak of MgO. Scherrer's formula with the constant K set to 0.9 is used to calculate the crystallite size.

[0036] [Method for manufacturing annealing separating agent] The annealing separating agent of this embodiment can be manufactured according to conventional methods. For example, an aqueous solution of calcium hydroxide is added to an aqueous solution of magnesium chloride and reacted to obtain a reaction product. Then, the obtained reaction product is filtered off, washed with water, and dried to obtain magnesium hydroxide. The obtained magnesium hydroxide is then calcined (for example, held at 800-1100°C for 10 minutes to 1 hour). This yields a powder of annealed separating agent containing magnesium oxide (MgO). The content of each component (element) in the annealing separation agent can be adjusted, for example, by adding compounds containing each element to the aforementioned aqueous magnesium chloride solution; or by adding compounds containing each element to magnesium hydroxide before calcination; etc. The crystallite size of MgO can be adjusted by the firing conditions described above. Specifically, increasing the firing temperature and / or increasing the firing time can increase the crystallite size of MgO. Conversely, decreasing the firing temperature and / or decreasing the firing time can decrease the crystallite size of MgO.

[0037] [Manufacturing method for grain-oriented electrical steel sheets] Grain-oriented electrical steel sheets can be manufactured using the annealing separating agent of this embodiment. The manufacturing method for grain-oriented electrical steel sheets is not particularly limited, and conventionally known manufacturing methods can be used. For example, a steel slab having a component composition suitable for grain-oriented electrical steel sheets is subjected to hot rolling and cold rolling, and the resulting steel sheet (cold-rolled sheet) is subjected to primary recrystallization annealing. Then, an annealing release agent is applied to the steel sheet, and then a finish annealing including secondary recrystallization annealing is performed. This forms a forsterite coating on the surface of the steel sheet.

[0038] The amount of annealing release agent applied (total value for both front and back surfaces, in terms of solid content) is, for example, 5.0 to 25.0 g / m². 2 However, this is not the only example. Furthermore, the conditions for primary recrystallization annealing and finish annealing are not particularly limited, and conventionally known conditions can be used as appropriate.

[0039] Subsequently, an insulating coating is formed by applying an insulating coating-forming treatment solution containing phosphate, colloidal silica, etc., to the surface of the forsterite coating and baking it. In this way, a grain-oriented electrical steel sheet comprising a steel sheet, a forsterite coating, and an insulating coating is obtained. Furthermore, the component composition of the insulating coating forming solution and the baking conditions are not particularly limited, and conventionally known ones can be used as appropriate.

[0040] Furthermore, by using the annealing separating agent of this embodiment as an annealing separating agent during the finish annealing process, a grain-oriented electrical steel sheet with excellent coating adhesion can be obtained. [Examples]

[0041] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below.

[0042] [Test 1] <Preparation of annealing separating agent> An aqueous solution of calcium hydroxide was added to an aqueous solution of magnesium chloride to obtain a reaction product. The obtained reaction product was then filtered, washed with water, and dried under an air atmosphere. Subsequently, the dried product was calcined under an air atmosphere (held at 950°C for 30 minutes). A powder of annealed separating agent having the component composition shown in Table 1 below (the remainder being MgO, the same applies hereafter) was obtained. At this time, the component composition of the final annealing separating agent was adjusted by adding compounds containing each element to the aqueous solution and / or dried magnesium chloride.

[0043] <Manufacturing of grain-oriented electrical steel sheets> A steel slab was prepared having a composition containing C:0.045 mass%, Si:3.25 mass%, Mn:0.070 mass%, Al:80 mass ppm, N:40 mass ppm, S:20 mass ppm, and Nb:40 mass ppm, with the remainder being Fe and unavoidable impurities. The prepared steel slab was heated to 1200°C, and then hot-rolled to obtain a 2.2 mm thick hot-rolled sheet. The obtained hot-rolled sheet was then hot-rolled and annealed at 1000°C for 30 seconds, and then cold-rolled to obtain a steel sheet (cold-rolled sheet) with a final thickness of 0.30 mm. Next, the obtained steel sheet was subjected to primary recrystallization annealing at 850°C for 90 seconds in a humid atmosphere, which also served as decarburization annealing. After that, 15.0 g / m² was applied to the surface of the steel sheet. 2 An annealing separator having the component composition shown in Table 1 below was applied in the specified amount (total value including both front and back surfaces). The steel sheet coated with the annealing separator was wound up, and the resulting coil was heated at a rate of 25°C / h and held at 1200°C for 20 hours to perform finish annealing. In this way, a forsterite coating was formed on the surface of the steel sheet. Subsequently, an insulating coating-forming treatment solution containing monomagnesium phosphate (100 parts by mass in terms of solid content), colloidal silica (120 parts by mass in terms of SiO2 solid content), and CrO3 (5 parts by mass in terms of metallic elements) was applied to the surface of the forsterite coating, and baking was performed at 900°C for 1 minute, which also served as planarization annealing. In this way, a grain-oriented electrical steel sheet comprising a steel sheet, a forsterite coating, and an insulating coating was obtained.

[0044] <evaluation> The obtained grain-oriented electrical steel sheets were subjected to the following tests to evaluate coating adhesion and coating appearance. The results are shown in Table 1 below.

[0045] Coating adhesion Five 300mm x 30mm test pieces were cut from the obtained grain-oriented electrical steel sheet, with the rolling direction as the longitudinal direction. Next, the test pieces were wrapped around round bars of different diameters at 5mm intervals, and the minimum diameter at which the forsterite coating did not peel off the steel sheet was confirmed at two locations (one on the front and one on the back) for each test piece. The average of the 10 minimum diameters obtained was calculated and this was determined as the minimum peel diameter (unit: mm) for that grain-oriented electrical steel sheet. A smaller minimum peel diameter indicates better coating adhesion. Table 1 below indicates the following: if the minimum peel diameter is 20 mm or less, select "A"; if it is between 20 mm and 30 mm, select "B"; if it is between 30 mm and 40 mm, select "C"; and if it is greater than 40 mm, select "D". From a practical standpoint, "A", "B", or "C" are preferred, "A" or "B" are more preferred, and "A" is even more preferred.

[0046] Appearance of the coating The surface appearance of the obtained grain-oriented electrical steel sheets was visually inspected, and the length of defects, such as patterns (distance in the rolling direction), was measured. The ratio of this length to the total coil length was calculated as the appearance defect rate. A smaller appearance defect rate indicates a superior coating appearance. Since insulating coatings generally transmit visible light, the appearance of the forsterite coating is the focus of the evaluation. Table 1 below indicates the following: "A" if the appearance defect rate was 1.0% or less, "B" if it was between 1.0% and 5.0%, and "C" if it was above 5.0%. From a practical standpoint, "A" or "B" is preferred, and "A" is more preferred.

[0047] [Table 1] TIFF0007893398000002.tif225115 TIFF0007893398000003.tif225101 TIFF0007893398000004.tif225116

[0048] <Summary of Evaluation Results> As shown in Table 1 above, grain-oriented electrical steel sheets No. 1-1 to No. 1-50 (inventive examples) had a coating adhesion rating of "B", while grain-oriented electrical steel sheets No. 1-51 to No. 1-52 (inventive examples) had a coating adhesion rating of "C". In contrast, grain-oriented electrical steel sheets No. 1-53 to No. 1-72 (comparative examples), in which the content of any of CaO, Fe2O3, Al2O3, Cl, F, Na, K, SO3, SiO2, and B was outside the specified range, had a coating adhesion rating of "D" and was insufficient.

[0049] [Exam 2] In the same manner as in Test 1, a powder of annealing separating agent having the component composition shown in Table 2 below was obtained. Using the obtained annealing separating agent, grain-oriented electrical steel sheets were obtained in the same manner as in Test 1. The obtained grain-oriented electrical steel sheets were evaluated for coating adhesion and coating appearance in the same manner as in Test 1. The results are shown in Table 2 below.

[0050] [Table 2]

[0051] <Summary of Evaluation Results> As shown in Table 2 above, M * S * and F * For numbers 2-7 to 2-12, where any of the specified parameters were outside the range, the coating adhesion was rated "B". In response to this, M * S * and F * Nos.2-1 to Nos.2-6, all of which fell within the specified range, had a coating adhesion rating of "A," indicating superior adhesion.

[0052] [Exam 3] In the same manner as in Test 1, a powder of annealing separating agent having the component composition shown in Table 3 below was obtained. Using the obtained annealing separating agent, grain-oriented electrical steel sheets were obtained in the same manner as in Test 1. The obtained grain-oriented electrical steel sheets were evaluated for coating adhesion and coating appearance in the same manner as in Test 1. The results are shown in Table 3 below.

[0053] [Table 3]

[0054] <Summary of Evaluation Results> As shown in Table 3 above, comparing No.3-1 to No.3-5, X *No.3-1 and No.3-5, which were outside the specified range, had a coating appearance of "C", but X * For samples No. 3-2 to No. 3-4, which fall within the specified range, the coating appearance was rated "B," indicating good quality. Similarly, comparing No.3-6 to No.3-10, X * No. 3-6 and No. 3-10, which were outside the specified range, had a coating appearance of "C", but X * For samples No. 3-7 to No. 3-9, which fall within the specified range, the coating appearance was rated "B," indicating good quality.

[0055] [Exam 4] In the same manner as in Test 1, a powder of annealing separating agent having the component composition shown in Table 4 below was obtained. However, when obtaining the annealing separating agent, the firing conditions (firing temperature and firing time) of the dried material were changed as appropriate. Using the obtained annealing separating agent, grain-oriented electrical steel sheets were obtained in the same manner as in Test 1. The obtained grain-oriented electrical steel sheets were evaluated for coating adhesion and coating appearance in the same manner as in Test 1. The results are shown in Table 4 below.

[0056] [Table 4]

[0057] <Summary of Evaluation Results> As shown in Table 4 above, samples No. 4-1 and No. 4-7, whose MgO crystallite size was outside the specified range, had a coating appearance of "B," while samples No. 4-2 to No. 4-6, whose MgO crystallite size was within the specified range, had a coating appearance of "A," indicating a better result.

Claims

1. It contains MgO, CaO content is 0.10 to 1.00% by mass, Fe ２ O ３ The content is 0.01 to 0.50% by mass. Al ２ O ３ Content 0.01 to 0.50% by mass Cl content is 0.005 to 0.100% by mass, F content is 0.001 to 0.100% by mass, Na content is 0.0001 to 0.0100% by mass. K content is 0.00001 to 0.01000% by mass, SO ３ The content is 0.010 to 0.500% by mass. SiO ２ The content is 0.01 to 1.00% by mass. The B content is 0.001 to 1.000% by mass. An annealing separation agent having an MgO content of 95.00% by mass or more.

2. M is represented by the following formula (1) ＊ The range is 1.30 to 1.

70. S is represented by the following formula (2) ＊ The range is 0.0300 to 0.0600. F represented by the following formula (3) ＊ The annealing release agent according to claim 1, wherein ＊ is 0.40 to 0.

60. M ＊ =3×[CaO]+2×[Fe ２ O ３ ]+[Al ２ O ３ ]・・・(1) S ＊ =[Cl]+2×[F]+5×[Na]+5×[K]・・・(2) F ＊ =[SiO ２ ]+5×[B]・・・(3) However, in formulas (1) to (3) above, [A] represents the content of component A in unit mass percent.

3. M is represented by the following formula (1) ＊ The range is 1.30 to 1.

70. S is represented by the following formula (2) ＊ The range is 0.0300 to 0.0600. F is represented by the following formula (3) ＊ The values ​​are 0.40 to 0.

60. X is represented by the following formula (4) ＊ The annealing separating agent according to claim 1, wherein the ratio is 0.50 to 3.

00. M ＊ =3×[CaO]+2×[Fe ２ O ３ ]+[Al ２ O ３ ]・・・(1) S ＊ =[Cl]+2×[F]+5×[Na]+5×[K]・・・(2) F ＊ =[SiO ２ ]+5×[B]・・・(3) X ＊ =(M ＊ ×S ＊ ) / ([SO ３ ]×F ＊ )・・・(4) However, in formulas (1) to (4) above, [A] represents the content of component A in unit mass percent.

4. An annealing separating agent according to any one of claims 1 to 3, wherein the crystallite size of MgO is 20 to 40 nm.

5. An annealing separating agent according to any one of claims 1 to 3, used in the manufacture of grain-oriented electrical steel sheets.

6. An annealing separating agent according to claim 4, used in the manufacture of grain-oriented electrical steel sheets.

Images