Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
  • C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F5/00—Compounds of magnesium
  • C01F5/02—Magnesia
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B35/00—Boron; Compounds thereof
  • C01B35/08—Compounds containing boron and nitrogen, phosphorus, oxygen, sulfur, selenium or tellurium
  • C01B35/10—Compounds containing boron and oxygen
  • C01B35/12—Borates
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1277—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
  • C21D8/1283—Application of a separating or insulating coating
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
  • H01F1/14766—Fe-Si based alloys
  • H01F1/14775—Fe-Si based alloys in the form of sheets
  • H01F1/14783—Fe-Si based alloys in the form of sheets with insulating coating
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/50—Solid solutions
  • C01P2002/52—Solid solutions containing elements as dopants
  • C01P2002/54—Solid solutions containing elements as dopants one element only
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/42—Magnetic properties
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2201/00—Treatment for obtaining particular effects
  • C21D2201/05—Grain orientation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the present invention relates to a mixed powder, MgO particles, a method for producing a grain-oriented electrical steel sheet, a method for producing MgO particles, and a method for producing a mixed powder.
• Grain-oriented electrical steel sheets are soft magnetic materials and are mainly used as core materials for transformers. Therefore, grain-oriented electrical steel sheets are required to have magnetic properties such as high magnetization properties and low iron loss. Iron loss is power loss consumed as thermal energy when an iron core is excited with an alternating magnetic field, and from the viewpoint of energy conservation, iron loss is required to be as low as possible.
• a manufacturing method including the following steps is applied to a steel slab adjusted to a predetermined composition: hot rolling, hot rolled sheet annealing, cold rolling, decarburization annealing, and finish annealing. be done.
• the steel plate wound into a coil is annealed at high temperature for a long time to integrate the crystal orientation into the Goss orientation, which has good magnetic properties (increases the degree of orientation integration).
• an annealing separator is applied to prevent the coil from seizing.
• an annealing separator containing magnesium oxide (MgO) as a main component is often used.
• MgO magnesium oxide
• SiO 2 silicon dioxide
• SiO 4 silicon dioxide
• a forsterite (Mg 2 SiO 4 )-based film (primary film) that plays the role of providing insulation. That is, by using an annealing separator containing MgO as a main component, it is possible not only to prevent seizure during final annealing but also to improve the magnetic properties of the grain-oriented electrical steel sheet.
• Patent Document 1 discloses a powder for an annealing separator containing 0.04% by mass or more and 0.30% by mass or less of boron and whose main component is magnesium oxide, in which 3-coordinated boron in the boron is A powder for an annealing separator is disclosed, characterized in that the ratio is 70% or more and 95% or less.
• Patent Document 2 is characterized in that a raw material containing one or both of magnesium hydroxide and magnesium carbonate and boron is fired, and then the tricoordinate boron ratio is adjusted by controlling the humidity of the fired product. , a method for producing a powder for an annealing separator, wherein the proportion of 3-coordinated boron in boron contained in the powder for annealing separator is 70% or more and 95% or less. A method is disclosed.
• Patent Documents 1 and 2 both state that 1) impurity purification is influenced by the film reaction behavior at high temperatures (1100°C or higher), and 2) the film reaction behavior at high temperatures is affected by the existence form of three coordinations. 3) Boron in the 4-coordination form not only does not contribute to the purification of impurities, but also invades the steel sheet during high-temperature annealing to form Fe 2 B, causing repeated bending deterioration.
• the proportion of 3-coordinated boron is defined based on the knowledge that
• Patent Documents 1 and 2 disclose that by controlling the amount of boron and the ratio of 3-coordinated boron in powder for annealing separator, poor coating appearance due to insufficient reactivity at high temperatures and impurities from the steel can be prevented. It is said that it can solve the problem of poor purification.
• magnetic properties and coating properties may be improved if the boron content in MgO is increased, but if the boron content is increased excessively, It has been found that if the temperature is increased, too much boron penetrates into the steel sheet, and a non-magnetic layer that inhibits secondary recrystallization develops, resulting in deterioration of magnetic properties. Therefore, the techniques disclosed in Patent Documents 1 and 2 cannot be said to be sufficient in improving magnetic properties and coating properties.
• the present invention has been made in view of the above problems, and is aimed at suppressing the adverse effect on secondary recrystallization due to the application of boron and producing grain-oriented electrical steel sheets with good magnetic properties and coating properties.
• the object of the present invention is to provide a mixed powder, MgO particles, a method for producing a grain-oriented electrical steel sheet, a method for producing MgO particles, and a method for producing a mixed powder.
• the present inventors have studied a method that can sufficiently obtain the magnetic properties and film properties due to boron even if the B content is suppressed. As a result, the inventors found that by suppressing the proportion of 3-coordinated boron in small MgO particles, which have high reactivity and undergo reactions at low temperatures, the inclusion of a large amount of B in steel sheets can be suppressed and secondary It was found that it is possible to suppress the negative effect on recrystallization.
• the mixed powder according to one aspect of the present invention is a mixed powder for an annealing separator containing MgO as a main ingredient, and the average particle size of the mixed powder is 0.10 ⁇ m or more and 8.50 ⁇ m or less, and The mixed powder contains B, and the B content contained in the entire mixed powder is 0.005% by mass or more and less than 0.040% by mass, and the proportion of 3-coordinated boron in the B is 5% by mass.
• the ratio of the circumferential length to the thickness of the primary particle of the MgO-containing particles is 6.0 or more.
• the mixed powder described in [1] above preferably contains Ca and satisfies the following formula (1). 0.05 ⁇ [Ca]/[BO 3 ] ⁇ 2.00...Formula (1)
• [Ca] is the Ca content (mass%) in the mixed powder
• [BO 3 ] is This is the content (% by mass) of the 3-coordinated boron in the mixed powder.
• the MgO particles according to another aspect of the present invention have an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, and a B content of 0.005 mass% or more and less than 0.040 mass%.
• the proportion of tricoordinated boron in B is 5% by mass or more and less than 70% by mass
• the ratio of the circumferential length to the thickness of the primary particle is 6.0 or more.
• the MgO particles described in [3] above preferably contain Ca and satisfy the following formula (2).
• the mixed powder according to [1] or [2] above or the MgO particles according to [3] or [4] above Use an annealing separator containing:
• a method for producing MgO particles according to yet another aspect of the present invention contains one or more selected from the group consisting of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate, Contains Mg-containing raw material particles having a circumferential length ratio to primary particle thickness of 7.0 or more and B-containing raw material particles containing B, and having an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less. A certain raw material powder is fired at a temperature of 700°C or higher and 1100°C or lower. [7] In the method for producing MgO particles described in [6] above, it is preferable that the raw material powder contains Ca in an amount of more than 0% by mass and not more than 0.02% by mass.
• the method for producing MgO particles according to yet another aspect of the present invention includes one or two B-containing particles selected from the group consisting of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate.
• Raw material particles containing the above, having an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, and a ratio of the circumference to the thickness of the primary particle of 7.0 or more, are heated at a temperature of 700°C or more and 1100°C or less. Fire.
• the raw material particles contain Ca in an amount of more than 0% by mass and not more than 0.02% by mass.
• a method for producing a mixed powder according to yet another aspect of the present invention contains one or more selected from the group consisting of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate, Contains Mg-containing raw material particles having a circumferential length ratio to primary particle thickness of 7.0 or more and B-containing raw material particles containing B, and having an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less.
• a certain raw material powder is fired at a temperature of 700°C or higher and 1100°C or lower.
• mixed powder, MgO particles, and grain-oriented electrical steel sheets are produced in order to suppress the adverse effects on secondary recrystallization due to the application of boron and to produce grain-oriented electrical steel sheets with good magnetic properties and coating properties.
• a method, a method for producing MgO particles, and a method for producing a mixed powder can be provided.
• a mixed powder according to an embodiment of the present invention is a mixed powder for an annealing separator containing MgO as a main ingredient, wherein the average particle size of the mixed powder is 0.10 ⁇ m or more and 8.50 ⁇ m or less, and the mixed powder contains B, the B content contained in the entire mixed powder is 0.005% by mass or more and less than 0.040% by mass, and the proportion of 3-coordinated boron in the B is 5% by mass or more and 70% by mass. % by mass, and the ratio of the circumferential length to the thickness of the primary particle of the MgO-containing particles is 6.0 or more. This will be explained in detail below.
• the mixed powder according to this embodiment has MgO as a main ingredient.
• the mixed powder contains, for example, 50.0% by mass or more of MgO.
• the proportion of MgO in the mixed powder is preferably 80.0% by mass or more, more preferably 90.0% by mass or more.
• the mixed powder contains MgO particles
• the MgO particles contained in the mixed powder are not limited to the MgO particles according to the embodiments of the present invention described below, and may include, for example, MgO particles such that the proportion of MgO in the mixed powder is 50% by mass or more. MgO particles can be used.
• the mixed powder according to this embodiment contains boron (B).
• the mixed powder includes, for example, B-containing particles containing B.
• the B- containing particles may contain at least one of pure boron and a B compound, and examples of the B compound include Na2B4O7 , borax, calcium borate, and magnesium borate. It will be done.
• Average particle size of mixed powder is 0.10 ⁇ m or more and 8.50 ⁇ m or less
• the average particle size of the mixed powder is 0.10 ⁇ m or more and 8.50 ⁇ m or less as a volume-based circle-equivalent average particle size. If the average particle size of the mixed powder is less than 0.10 ⁇ m, the reactivity will be too high, the reaction with the coating will be significant at low temperatures, the feeding rate of Mg and B will also be high, and precipitates during secondary recrystallization will increase. decomposition is promoted, and crystal grains other than the Goss orientation tend to grow. As a result, the magnetic properties deteriorate.
• the average particle size of the mixed powder is set to 0.10 ⁇ m or more.
• the average particle size of the mixed powder is preferably 0.15 ⁇ m or more, more preferably 0.30 ⁇ m or more.
• the average particle size of the mixed powder exceeds 8.50 ⁇ m, it becomes difficult to adhere to the steel plate and the MgO layer, promoting degassing, and deteriorating the heat resistance of precipitates. crystal grains grow more easily. As a result, the magnetic properties deteriorate.
• the average particle size of the mixed powder is preferably 7.50 ⁇ m or less, more preferably 7.00 ⁇ m or less.
• the average particle size of the mixed powder is determined by measuring the volume frequency particle size distribution using a laser diffraction particle size distribution analyzer (LA-920, manufactured by HORIBA Co., Ltd.), and determining the average particle size in terms of circle equivalent diameter. Particle size.
• the measurement conditions are that the refractive index is 1.74 and the dispersion treatment is performed using ultrasonic waves in pure water.
• the mixed powder contains 0.005% by mass or more and less than 0.040% by mass of boron.
• the B content is preferably 0.006% by mass or more, more preferably 0.008% by mass or more.
• the B content in the mixed powder is set to less than 0.040% by mass.
• the B content is preferably 0.035% by mass or less.
• the B content of the mixed powder is determined by quantitative analysis using inductively coupled plasma mass spectrometry (ICP-MS). Quantitative analysis by ICP-MS is performed by dissolving MgO powder in a mixed acid of hydrochloric acid and nitric acid. At this time, if there is any undissolved residue, the residue is collected, dissolved in an alkaline solution, and analyzed.
• ICP-MS inductively coupled plasma mass spectrometry
• the proportion of 3-coordinated boron in B is 5% by mass or more and less than 70% by mass]
• the boron contained in the mixed powder exists in the form of 3-coordinated boron (BO 3 ) and 4-coordinated boron (BO 4 ).
• 3-coordinate boron is boron that has a 3-coordinate structure in which three oxygen atoms are coordinated around a boron element
• 4-coordinate boron is a boron that has a 3-coordinate structure in which 4 oxygen atoms are coordinated around a boron element.
• Boron has a four-coordinated structure. Boron other than 3-coordinated boron exists as 4-coordinated boron.
• 3-coordinated boron promotes film formation more than 4-coordinated boron while having a greater effect on the decomposition of precipitates. It has also been found that when the amount of tricoordinated boron is too high, the reactions of film formation and decomposition of precipitates occur too concentrated at low temperatures, resulting in film destruction due to gas release. Therefore, it was found that by shifting the timing of the decomposition of the precipitates, it was possible to form a good film while preventing film destruction.
• the mixed powder according to the present embodiment contains 3-coordinated boron in an amount of 5% by mass or more and less than 70% by mass with respect to the content of B in the mixed powder.
• the proportion of tricoordinated boron in B is 5% by mass or more, magnetic properties and film properties can be improved. Therefore, the proportion of 3-coordinated boron in B is 5% by mass or more.
• the proportion of 3-coordinated boron in B is preferably 8% by mass or more, more preferably 10% by mass or more.
• the proportion of tricoordinated boron in B is 70% by mass or more, the reactivity becomes too high, the decomposition of precipitates is promoted, and crystal grains with orientations other than Goss orientation tend to grow. As a result, magnetic properties deteriorate. Therefore, the proportion of 3-coordinated boron in B is less than 70% by mass.
• the proportion of 3-coordinated boron in B is preferably 68% by mass or less, more preferably 65% by mass or less. Note that tricoordinate boron is mainly contained in the B-containing particles described above, but may also be contained in MgO particles and Al-containing particles.
• the proportion of 3-coordinated boron in the B contained in the mixed powder is determined by the following method. Measurement was performed using NMR (Nuclear Magnetic Resonance), and in the obtained spectrum, peaks in the range of 27 ppm or less and 6 ppm or more were 3-coordinated boron, and peaks in the range of less than 6 ppm and -6 ppm or more were 4
• the coordinated boron the value obtained by dividing the integrated area of the peak of 3-coordinated boron by the total integrated area of the integrated area of the peak of 3-coordinated boron and the integrated area of the peak of 4-coordinated boron is the 3-coordinated boron of B. This is the proportion of boron.
• the ratio of the circumference to the thickness of the primary particles of the MgO-containing particles is 6.0 or more
• the ratio of the circumference to the thickness of the primary particles of the MgO-containing particles is 6.0 or more. Since the MgO particles according to the present embodiment have a shape in which the ratio of the circumferential length to the thickness of the primary particle of the MgO-containing particles is 6.0 or more, the annealing separator containing the mixed powder according to the present embodiment When is applied to the surface of a steel sheet and dried, the annealing separator coats the surface of the steel sheet, improving reactivity, and the effect of improving film properties by applying boron is more likely to be exhibited.
• the ratio of the circumferential length to the thickness of the primary particles of the MgO-containing particles may be 8.0 or more, or 9.1 or more.
• the ratio of the circumferential length to the thickness of the primary particle of the particles containing MgO may be, for example, 11.5 or less, or 11.2 or less.
• the thickness of the MgO primary particles is calculated by the following method. Before mixing, MgO particles are used as the target for thickness calculation, and after mixing, using SEM (Scanning Electron Microscope)-EDS (Energy dispersive X-ray spectroscopy). Elemental analysis of Mg is performed, and primary particles included in secondary particles that contain the most Mg, which are identified from elemental mapping showing the process of Mg concentration, are used as calculation targets.
• SEM Sccanning Electron Microscope
• EDS Electronic X-ray spectroscopy
• the MgO particles or mixed powder before mixing were observed with a SEM at a magnification of 10,000 times, and the obtained secondary electron image showed that the identified MgO particles were attached to the surface of the MgO secondary particles and the contrast was
• the contour is determined based on the contour, and particles that are not hidden by the contours of other particles are used as targets for calculating the thickness of the primary particles.
• a projection onto a plane is obtained. Tracing is performed by determining the contour from the contrast of the secondary electron image using image analysis software ImageJ (developed by NIH; National Institutes of Health).
• ImageJ developed by NIH; National Institutes of Health
• the median distance between two points of each of the 20 primary particles is defined as the thickness of the MgO primary particle.
• the center of gravity is determined by tracing the outline with a black line in the secondary electron image, then filling in the area surrounded by the outline with black, and filling in the outside of the primary particle with white, using the center of gravity measurement function in the image analysis software ImageJ. demand.
• the median length of the contour lines of 20 primary particles is defined as the circumference. In this embodiment, the circumferential length calculated in this manner is 6.0 times or more the thickness.
• Cl chlorine
• Cl chlorine
• the mixed powder according to this embodiment contains 0.005% by mass or more of Cl, since this further improves the film properties.
• the Cl content is more preferably 0.008% by mass or more.
• the Cl content is preferably 0.030% by mass or less.
• the Cl content is more preferably 0.022% by mass or less.
• the total of one or more selected from the group consisting of Ca, Sr, and Ba is 0.02% by mass or more and 4.00% by mass or less
• Ca (calcium), Sr (strontium), and Ba (barium) are elements that increase the reactivity of SiO 2 and the mixed powder. Therefore, it is preferable to contain a total of 0.02% by mass or more of one or more selected from the group consisting of Ca, Sr, and Ba, since this further improves the film properties.
• the total content of one or more selected from the group consisting of Ca, Sr, and Ba exceeds 4.00% by mass, desulfurization of the steel sheet may be caused due to its strong sulfidation tendency. .
• the total content of one or more selected from the group consisting of Ca, Sr, and Ba is 4.00% by mass or less, desulfurization can be sufficiently suppressed. Therefore, the total content of one or more selected from the group consisting of Ca, Sr, and Ba is preferably 4.00% by mass or less.
• Ca may be contained in the mixed powder as a Ca compound.
• the Ca compound include calcium sulfate, gypsum hemihydrate, calcined gypsum, and gypsum.
• Sr may be contained in the mixed powder as an Sr compound.
• Examples of the Sr compound include strontium sulfate.
• Ba may be contained in the mixed powder as a Ba compound. Examples of the Ba compound include barium sulfate.
• Cl, Sr, and Ba may be contained in the mixed powder as particles mainly containing each of them, or may be contained in the above-mentioned particles constituting the mixed powder.
• Ti 0.25% by mass or more and 5% by mass or less
• Ti titanium is an element that maintains the oxygen potential of the steel sheet by releasing oxygen at high temperatures during final annealing, and helps film formation.
• the Ti content is more preferably 0.5% by mass or more.
• the Ti content is preferably 5% by mass or less.
• the Ti content is more preferably 4% by mass or less.
• Ti can be included in the mixed powder, for example, as TiO 2 , titanate, TiN, TiB 2 , BaTiO 3 .
• Ti may be contained in the mixed powder as particles mainly containing each compound, or may be contained in the aforementioned particles constituting the mixed powder.
• impurities Components other than the above in the mixed powder according to this embodiment are MgO and impurities.
• impurities include Al, Fe, and Si. If the content of each impurity element is 0.04% by mass or less, or the total amount is 0.1% by mass or less, the influence on the magnetic properties or coating properties of the grain-oriented electrical steel sheet is small.
• the mixed powder according to the present embodiment contains Ca and satisfies the following formula (1).
• [Ca]/[BO 3 ] When [Ca]/[BO 3 ] satisfies the above formula (1), the amount of tricoordinated boron in SiO 2 is maintained by Ca, the precipitate decomposition rate becomes constant, and the magnetic properties are further improved.
• [Ca]/[BO 3 ] is more preferably 0.10 or more, still more preferably 0.15 or more. Moreover, [Ca]/[BO 3 ] is more preferably 0.40 or less, still more preferably 0.30 or less.
• the content of 3-coordinated boron in the mixed powder [BO 3 ] can be determined by multiplying the B content determined by ICP-MS by the proportion of 3-coordinated boron in B determined by the method described above. Desired.
• the mixed powder according to the present embodiment described above contains magnesium hydroxide (Mg(OH) 2 ), basic magnesium carbonate (mMgCO 3 .Mg(OH) 2 .nH 2 O), and magnesium carbonate (Mg(CO 3 ) ) Mg-containing raw material particles containing one or more types selected from the group consisting of , and has an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, and is produced by firing a raw material powder at a temperature of 700° C. or more and 1100° C. or less.
• the ratio of the circumferential length to the thickness of the primary particles of the Mg-containing raw material particles is 7.0 or more. If the ratio of the circumferential length to the thickness of the primary particles is 7.0 or more, in the mixed powder after firing, the ratio of the circumferential length to the thickness of the primary particles of the MgO-containing particles is 6.0 or more.
• the ratio of the circumferential length to the thickness of the primary particles of the Mg-containing raw material particles may be 7.6 or more, or may be 9.4 or more.
• the ratio of the circumferential length to the thickness of the primary particles of the Mg-containing raw material particles may be, for example, 24.0 or less, or 20.0 or less.
• the ratio of the circumferential length to the thickness of the primary particles of the Mg-containing raw material particles is calculated by the same method as the method for calculating the ratio of the circumferential length to the thickness of the primary particles of the MgO-containing particles described above.
• B-containing raw material particles include B, BN, B2O3 , Na2B4O7 , borax, and the like .
• the B-containing raw material particles contain, for example, 10% by mass or more of B.
• the particle sizes of the Mg-containing raw material particles and the B-containing raw material particles that constitute the raw material powder may be, for example, a particle size that provides the average particle size of the mixed powder described above, or a larger particle size. There may be.
• the particle size may be adjusted by a known method such as pulverizing or classifying the fired raw material powder.
• Each particle size of the Mg-containing raw material particles and the B-containing raw material particles may be, for example, 0.05 ⁇ m or more, or 0.08 ⁇ m or more. Further, each particle size of the Mg-containing raw material particles and the B-containing raw material particles may be, for example, 10.0 ⁇ m or less, or 8.0 ⁇ m or less.
• the raw material powder may contain Cl, Ca, Sr, Ba, and Ti as appropriate. When these elements are contained in the raw material powder, it is sufficient that one particle contains one or more of these elements.
• Ca is contained in Ca-containing raw material particles containing a Ca compound. Examples of the Ca compound include calcined gypsum, strontium sulfate, and barium sulfate.
• the Ca-containing raw material particles contain, for example, 10% by mass or more of Ca.
• the B content in the raw material powder is preferably 0.005% by mass or more and 0.040% by mass or less. If the B content of the raw material particles is 0.005% by mass or more and 0.040% by mass or less, the B content of the MgO particles produced more reliably is 0.005% by mass or more and 0.040% by mass or less. be able to.
• the B content is more preferably 0.006% by mass or more, and still more preferably 0.008% by mass or more. Further, the B content is more preferably 0.035% by mass or less, still more preferably 0.030% by mass or less. However, if the raw material powder contains a component that volatilizes during firing, the B content in the raw material powder is adjusted in consideration of the amount of the component.
• B is mainly contained in the above-mentioned B-containing raw material particles, but may also be contained in other particles constituting the raw material powder, such as Mg-containing raw material particles and Ti-containing particles.
• the B content in the raw material powder is quantitatively analyzed by ICP-MS using the method described above.
• the raw material particles are fired at a temperature of 700° C. or more and 1100° C. or less in an air atmosphere or a nitrogen atmosphere. It is not preferable for the firing atmosphere to be other than air atmosphere or nitrogen atmosphere because it is economically disadvantageous. Furthermore, if the firing temperature is less than 700°C, the firing will be insufficient. Therefore, the firing temperature is set to 700°C or higher. The firing temperature is preferably 750°C or higher, more preferably 800°C or higher. On the other hand, by setting the firing temperature to 1100°C or lower, the chemical structure of the fired tricoordinated boron is stabilized, and the proportion of tricoordinated boron in the fired MgO particles is increased without significantly changing the particle size. be able to. Therefore, the firing temperature is set to 1100°C or less. The firing temperature is preferably 1050°C or lower, more preferably 1030°C or lower.
• the firing time can be, for example, 5 minutes or more and 120 minutes or less. From the viewpoint of eliminating uneven firing, the firing time is preferably 8 minutes or more, more preferably 10 minutes or more. On the other hand, from the viewpoint of economy, the firing time is preferably 90 minutes or less, more preferably 60 minutes or less. Up to this point, the method for producing the mixed powder has been described.
• the raw material powder contains Mg-containing raw material particles, B-containing raw material particles, and Al-containing raw material particles, on the premise that the particles serving as the Mg source and the particles serving as the B source are different from each other.
• the aspects including this have been explained.
• the present invention is not limited to this embodiment, and may contain B or other elements so that the Mg-containing raw material particles that serve as the Mg source serve as the B source.
• the B-containing raw material particles may contain other elements.
• the mixed powder according to the present embodiment described above has an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, the mixed powder contains B, and the proportion of 3-coordinated boron in the B is 5 mass % or more and less than 70% by mass.
• the MgO particles according to an embodiment of the present invention have an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, and a B content of 0.005 mass% or more and less than 0.040 mass%, The proportion of tricoordinated boron is 5% by mass or more and less than 70% by mass, and the ratio of the circumferential length to the thickness of the primary particle of the MgO-containing particle is 6.0 or more.
• the above-mentioned characteristics of the MgO particles according to this embodiment are similar to those of the mixed powder described above, so a detailed description thereof will be omitted here. However, when the MgO particles contain the above components, it means that the above components are contained in the MgO particles constituting the MgO powder, and it does not mean that particles other than the MgO particles are present alone.
• MgO particles described above are manufactured by the following manufacturing method (I) or (II).
• (II) Contains B, contains one or more selected from the group consisting of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate, has an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, and has a primary Raw material particles having a ratio of circumferential length to particle thickness of 7.0 or more are fired at a temperature of 700° C. or more and 1100° C. or less. Each manufacturing method will be explained below.
• Manufacturing method (I) In the production method (I), one or more selected from the group consisting of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate are contained, and the ratio of the circumferential length to the thickness of the primary particles is 7.
• the raw material powder which contains Mg-containing raw material particles that are 0 or more and B-containing raw material particles that contain B, and has an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, is heated at a temperature of 700° C. or more and 1100° C. or less. It is fired in If the raw material powder contains a component that volatilizes during firing, the B content is adjusted in consideration of the amount of the component.
• This manufacturing method is basically the same as the manufacturing method of mixed powder. However, in the method for manufacturing the mixed powder described above, there are cases where oxides other than B and Al, which are dissolved or not contained as impurities in the MgO particles, are mixed and fired. This is different from the manufacturing method of mixed powder.
• B is contained, one or more selected from the group consisting of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate, and the average particle size is 0.10 ⁇ m or more.
• Raw material particles having a diameter of 8.50 ⁇ m or less and a ratio of the circumferential length to the thickness of the primary particles of 7.0 or more are fired at a temperature of 700° C. or more and 1100° C. or less. If the raw material powder contains a component that volatilizes during firing, the B content is adjusted in consideration of the amount of the component.
• the raw material particles containing at least one of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate contain B.
• the B content is preferably 0.005% by mass or more and 0.040% by mass or less. If the B content of the raw material particles is 0.005% by mass or more and 0.040% by mass or less, the B content of the manufactured MgO particles is more reliably set to 0.005% by mass or more and 0.040% by mass or less. be able to.
• the B content is more preferably 0.006% by mass or more, and still more preferably 0.008% by mass or more. Further, the B content is more preferably 0.035% by mass or less, and still more preferably 0.030% by mass or less.
• the content of tricoordinated boron relative to the B content in the raw material particles is preferably 5% by mass or more and 70% by mass or less. If the content of 3-coordinated boron relative to the B content is within the above range, the content of 3-coordinated boron in the MgO particles after firing under the firing conditions described below will be 5% by mass or more and less than 70% by mass.
• the particle size of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate may be, for example, a particle size that provides the average particle size of the MgO particles described above, or a particle size larger than that. There may be.
• the MgO particles obtained by firing may be pulverized or classified by a known method.
• Each particle size of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate may be, for example, 0.05 ⁇ m or more, or 0.08 ⁇ m or more.
• each particle size of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate may be, for example, 10.0 ⁇ m or less, or 8.0 ⁇ m or less.
• the ratio of the circumferential length to the thickness of the primary particles of the raw material particles is 7.0 or more. If the ratio of the circumferential length to the thickness of the primary particles is 7.0 or more, the ratio of the circumferential length to the thickness of the primary particles of the raw material particles will be 6.0 or more in the mixed powder after firing.
• the ratio of the circumferential length to the thickness of the primary particles of the raw material particles may be 7.6 or more, or may be 9.4 or more.
• the ratio of the circumferential length to the thickness of the primary particles of the raw material particles may be, for example, 20.0 or less, or 15.0 or less.
• the ratio of the circumferential length to the thickness of the primary particles of the raw material particles is calculated by the same method as the method for calculating the ratio of the circumferential length to the thickness of the primary particles of the MgO-containing particles described above.
• the raw material particles are fired at a temperature of 700°C or more and 1100°C or less in an air atmosphere or a nitrogen atmosphere.
• the firing atmosphere, firing temperature, and firing time are the same as the firing conditions for the raw material particles described above, so a detailed description thereof will be omitted here.
• a method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention is produced using the above-mentioned MgO particles or mixed powder as an annealing separator.
• the method for producing a grain-oriented electrical steel sheet according to the present embodiment includes, for example, a hot rolling step of hot rolling a steel slab to obtain a hot rolled sheet, and a hot rolled sheet annealing step of annealing the hot rolled sheet.
• a cold rolling step in which the hot rolled sheet after the hot rolled sheet annealing step is cold rolled to obtain a cold rolled sheet
• a decarburization annealing step in which the cold rolled sheet is decarburized annealed;
• a manufacturing method including a finish annealing step of applying an annealing separator containing the MgO particles or mixed powder to the cold rolled sheet after the charcoal annealing step, drying it, and then performing finish annealing.
• a grain-oriented electrical steel sheet can be manufactured.
• an annealing separator prepared by mixing the mixed powder according to the embodiment described above and water to form a slurry is used.
• Ti may be further mixed.
• this annealing separator grain-oriented electrical steel sheets with excellent coating appearance and coating adhesion can be produced.
• known manufacturing conditions for grain-oriented electrical steel sheets can be applied to the chemical composition of the steel slab and the conditions for each step, except for the annealing separator used.
• the annealing separator is TiO 2 when the mass of the mixed powder is 100%. It is preferable to mix at a ratio of 0.5 to 8.5% in terms of Ti content.
• the conditions in the examples are examples of conditions adopted to confirm the feasibility and effects of the present invention. It is not limited to the conditions.
• the present invention can adopt various conditions as long as the purpose of the present invention is achieved without departing from the gist of the present invention.
• a grain-oriented electrical steel sheet was produced using MgO particles or a mixed powder of MgO particles and TiO 2 particles shown in Table 1A.
• an aqueous slurry of an annealing separator containing MgO particles or mixed powder shown in Table 1A was applied to a cold rolled steel sheet after primary recrystallization annealing.
• An aqueous slurry was prepared by mixing the MgO powder or mixed powder shown in Table 1 and water.
• the content of solids (MgO particles or mixed powder) in the aqueous slurry was 20% by mass.
• the cold-rolled steel sheet coated with the aqueous slurry was baked at 300° C.
• the thickness of the MgO primary particles was measured by the following method.
• a secondary electron image of the mixed powder was obtained using a SEM at a magnification of 10,000 times, and MgO particles were identified from the obtained secondary electron image by the following method. That is, elemental analysis of Mg was performed using SEM-EDS, and secondary particles containing the most Mg identified from elemental mapping showing the process of Mg concentration were used as MgO particles to be calculated.
• the identified MgO particles from the obtained secondary electron image, the identified MgO particles are attached to the surface of the MgO secondary particles, the outline is determined based on the contrast, and other particles are determined. Particles that were not hidden by the contour were judged to be primary particles.
• the outline of the primary particle in the secondary electron image was traced using ImageJ to obtain a projection onto a plane.
• the median distance between two points of 20 primary particles was defined as the thickness of the MgO primary particles.
• the median length of the contour lines of 20 primary particles was defined as the circumference. From the calculated thickness and circumference, the ratio of the circumference to the thickness of the primary particle of the MgO particles was calculated.
• the perimeter/thickness in Table 1A indicates the ratio of the perimeter to the thickness of the primary particles of the MgO particles.
• the B content and Ca content of the MgO particles and mixed powder were measured using inductively coupled plasma mass spectrometry (ICP-MS). Specifically, a solution of MgO particles or mixed powder dissolved in a mixed acid of hydrochloric acid and nitric acid was used. If a residue remained, it was collected, dissolved in an alkaline solution, and analyzed. Further, the proportion of 3-coordinated boron in B was determined by the following method. Measurement was carried out by NMR, and in the obtained spectrum, peaks in the range of 27 ppm or less and 6 ppm or more were defined as 3-coordinated boron, and peaks in the range of less than 6 ppm and -6 ppm or higher were defined as 4-coordinated boron.
• ICP-MS inductively coupled plasma mass spectrometry
• the value obtained by dividing the integral area of the peak by the total integral area of the integral area of the peak of 3-coordinated boron and the integral area of the peak of 4-coordinated boron was taken as the ratio of 3-coordinated boron in B.
• the BO 3 content [BO 3 ] of the MgO particles and mixed powder was determined by multiplying the B content determined by ICP-MS by the proportion of tricoordinated boron in B.
• the volume frequency particle size distribution of the MgO particles and mixed powder was measured using a laser diffraction particle size distribution analyzer (manufactured by HORIBA Co., Ltd., LA-920), and the average particle size in equivalent circle diameter was calculated as the average particle size of the MgO particles and mixed powder. It was taken as the average particle size.
• the measurement conditions were a refractive index of 1.74 and a dispersion treatment using pure ultrasonic waves.
• the obtained grain-oriented electrical steel sheet was evaluated for magnetic properties (B8), appearance, film adhesion, and magnetic property deterioration amount ⁇ B8 in the following manner.
• Magnetic properties The magnetic properties of each grain-oriented electrical steel sheet were evaluated using the following method. Specifically, a magnetic field of 800 A/m was applied to a sample measuring 300 mm in length in the rolling direction and 60 mm in width to determine the magnetic flux density B8. When B8 was 1.920T or more, it was determined that the magnetic properties were good.
• each grain-oriented electrical steel sheet sample was evaluated for color tone, and then a known insulating film was formed and film defects were evaluated.
• the appearance of each grain-oriented electrical steel sheet was judged to be excellent if the color tone of the primary coating before the insulation coating was formed was uniform and there were no coating defects (holes or rust) after the insulation coating was formed. Specifically, it was evaluated as follows. A: The color tone is uniform before the insulation coating is formed, and the maximum area of coating defects after the insulation coating is formed is less than 2 mm2 .
• B The color tone is uniform before the insulation coating is formed, and the maximum area of coating defects after the insulation coating is formed. The maximum area of coating defects is 2 to 4 mm 2.
• C There is uneven color tone before the insulation coating is formed, or the maximum area of coating defects after the insulation coating is formed is over 4 mm 2. Evaluation is A or B. I judged that I passed.
• the average particle size is 0.10 ⁇ m or more and 8.50 ⁇ m or less
• the B content is 0.005 mass% or more and less than 0.040 mass%
• 3 of B The proportion of coordinated boron is 5% by mass or more and less than 70% by mass
• the ratio of the circumference to the thickness of the primary particle of the MgO-containing particle is 6.0 or more
• the appearance, film adhesion, and magnetism are A grain-oriented electrical steel sheet with an excellent property deterioration amount ⁇ B8 was obtained.
• the [Ca]/[BO 3 ] value was within the range of 0.05 or more and less than 2.00
• the amount of magnetic property deterioration ⁇ B8 was small, and good magnetic properties were obtained.
• Example 2 A grain-oriented electrical steel sheet was manufactured using the mixed powder shown in Table 2B containing MgO particles, B-containing particles, and TiO 2 particles at the blending ratio shown in Table 2A. Specifically, an aqueous slurry of an annealing separator containing the mixed powder shown in Table 2B was applied to the cold rolled steel sheet after primary recrystallization annealing. An aqueous slurry was prepared by mixing the mixed powder shown in Table 2B and water. The content of solids (mixed powder) in the aqueous slurry was 20% by mass. In each case, a cold rolled steel plate with an aqueous slurry applied to its surface was subjected to a baking treatment at 300° C.
• a steel plate having a base steel plate and a glass coating containing a composite oxide such as forsterite (Mg 2 SiO 4 ) having a length in the longitudinal direction of 60 mm, a length in the width direction of the plate 300 mm, and a plate thickness of 0.23 mm is produced.
• a grain-oriented electrical steel sheet was manufactured.
• the ratio of circumference to thickness was measured in the same manner as in Example 1. Further, the obtained grain-oriented electrical steel sheet was evaluated in the same manner as in Example 1 for magnetic properties (B8), appearance, film adhesion, and magnetic property deterioration amount ⁇ B8. The results are shown in Table 2B.
• the B content in the mixed powder was too low, resulting in poor film adhesion.
• the average particle size is 0.10 ⁇ m or more and 8.50 ⁇ m or less
• the mixed powder contains B
• the B content in the whole mixed powder is 0.005% by mass or more and 0.040% by mass.
• the proportion of 3-coordinated boron in B is 5% by mass or more and less than 70% by mass
• the ratio of the circumference to the thickness of the primary particle of the MgO-containing particle is 6.0 or more.
• B8 a grain-oriented electrical steel sheet with excellent appearance, film adhesion, and magnetic property deterioration amount ⁇ B8 was obtained.
• Example 3 Using the mixed powder shown in Table 3B containing MgO particles shown in Table 3A, B-containing particles, Ca-containing particles, and TiO 2 particles, and under the same conditions as in Example 2, directional electromagnetic Manufactured steel plates. Specifically, an aqueous slurry of an annealing separator containing the mixed powder shown in Table 3B was applied to the cold rolled steel sheet after primary recrystallization annealing. The aqueous slurry was prepared by mixing the mixed powder shown in Table 3B and water. The content of solids (mixed powder) in the aqueous slurry was 20% by mass.
• a cold rolled steel plate with an aqueous slurry applied to its surface was subjected to a baking treatment at 300° C. for 30 seconds to dry the aqueous slurry and bake the solid content.
• a final annealing treatment was performed.
• the temperature was maintained at 1200° C. for 20 hours in all examples.
• the ratio of circumference to thickness was measured in the same manner as in Example 1. Further, the obtained grain-oriented electrical steel sheet was evaluated in the same manner as in Example 1 for magnetic properties (B8), appearance, film adhesion, and magnetic property deterioration amount ⁇ B8. The results are shown in Table 3B.
• the average particle size is 0.10 ⁇ m or more and 8.50 ⁇ m or less
• the mixed powder contains B
• the B content in the entire mixed powder is 0.005% by mass. or more and less than 0.040 mass%
• the proportion of tricoordinated boron in B is 5 mass% or more and less than 70 mass%
• the ratio of the circumference to the thickness of the MgO primary particles is 6.0 or more.
• a grain-oriented electrical steel sheet with excellent B8, appearance, film adhesion, and magnetic property deterioration amount ⁇ B8 was obtained. Especially No. In Examples Nos.
• the [Ca]/[BO 3 ] value was within the range of 0.05 or more and less than 2.00, the amount of magnetic property deterioration ⁇ B8 was small, and good magnetic properties were obtained.
• the B content of the mixed powder was more than 0.040%, and the magnetic property deterioration amount ⁇ B8 of the grain-oriented electrical steel sheet manufactured using the mixed powder was inferior.
• Example 4 The raw material particles or raw material powder shown in Table 4A were fired under the conditions shown in Table 4B to produce MgO particles or mixed powder.
• a grain-oriented electrical steel sheet was manufactured in the same manner as in Example 1 using the manufactured MgO particles or mixed powder.
• the average particle diameter, the ratio of the circumference to the thickness of the primary particle of the Mg-containing raw material particles, and the ratio of the circumference to the thickness of the primary particle of the MgO particles in the MgO particles or mixed powder were measured in the same manner as in Example 1. It was done. Further, the obtained grain-oriented electrical steel sheet was evaluated in the same manner as in Example 1 for magnetic properties (B8), appearance, film adhesion, and magnetic property deterioration amount ⁇ B8. The results are shown in Table 4B.
• Examples 37 and 39 the B content of the MgO particles was too low, resulting in poor film adhesion.
• examples No. 38 and 40 the B content of the MgO particles was excessive, and the amount of magnetic property deterioration ⁇ B8 was inferior.
• Mg-containing raw material particles containing one or more selected from the group consisting of magnesium hydroxide, basic magnesium carbonate, and magnesium carbonate, and B containing B A raw material powder containing the containing particles and having an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less was fired at a temperature of 700° C. or more and 1100° C. or less.
• the MgO particles obtained after firing have an average particle size of 0.10 ⁇ m or more and 8.50 ⁇ m or less, a B content of 0.005% by mass or more and less than 0.040% by mass, and 3-coordination of B. Since the proportion of boron was 5% by mass or more and less than 70% by mass, and the ratio of the circumference to the thickness of the primary particle of the MgO-containing particles was 6.0 or more, B8, appearance, film adhesion, and magnetic properties A grain-oriented electrical steel sheet with an excellent amount of deterioration ⁇ B8 was obtained. Especially No. In the examples of Nos.
• the [Ca]/[BO 3 ] value is within the range of 0.05 or more and less than 2.00, the amount of magnetic property deterioration ⁇ B8 is small, and good magnetic properties are obtained.
• Example No. 49 the firing temperature was too high, so the average particle size of the mixed powder was out of range, and the appearance and film adhesion of the grain-oriented electrical steel sheet were inferior.
• the ratio of the circumferential length to the primary particle thickness of the Mg-containing raw material particles is less than 7.0, and the ratio of the circumferential length to the primary particle thickness of the MgO particles in the MgO particles or mixed powder is 6.0. It was less than 0, and the film adhesion was inferior.

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