An insulating material-coated soft magnetic powder includes: a core particle that includes a base portion containing a soft magnetic material containing Fe as a main component and at least one of Si, Cr, and Al, and that includes an oxide film provided on a surface of the base portion and containing an oxide of at least one of Si, Cr, and Al; and an insulating film that is provided on a surface of the core particle and that contains a ceramic, in which a thickness of the insulating film is 5 nm or more and 300 nm or less, and the oxide contained in the oxide film and the ceramic contained in the insulating film are mutually diffused at an interface between the oxide film and the insulating film.

A grain-oriented electrical steel sheet according to an embodiment of the present invention has an average degree of orientation difference of 0.5 to 10° between recrystallized grains that are in contact with a groove present on the surface of the electrical steel sheet and the bottom of the groove, and other recrystallized grains.

A preparation method of glassless grain-oriented silicon steel includes the following operations. During a decarburization annealing, a thickness of an oxide film on a surface of strip is 1.5-2.5 μm; an atomic weight ratio of Si element and Fe element in the oxide film satisfies: Si/(Si+Fe)≥0.76; during a high-temperature annealing, a cooling stage includes sequentially: cooling with an inner cover when a temperature drops from 1200° C. to 500° C.; wherein a protective gas is a mixed gas containing nitrogen and hydrogen, and a volume percentage of the hydrogen in the mixed gas is >3%; cooling with the inner cover when the temperature drops from 500° C. to 200° C.; wherein the protective gas is nitrogen; and cooling in air by removing the inner cover when the temperature is <200° C.

An electrical steel sheet is described, which has an insulating coating on its surface. The insulating coating is free of chromium and comprises plate-like particles of inorganic compound and a metal phosphate. The plate-like particles of inorganic compound are in the form of secondary particles, which are formed by aggregating primary particles, and present in an amount of not less than 0.1 parts by mass and not greater than 20 parts by mass, with respect to 100 parts by mass of the metal phosphate. The secondary particles have an average particle diameter of no less than 0.05 μm and no greater than 5 μm, and have a specific surface area of 1 to 80 m.sup.2/g. The primary particles have an aspect ratio of 50 to 1000. The electrical steel sheet has excellent heat resistance, corrosion resistance, appearance, and insulating properties.

An electrical steel sheet is described, which has an insulating coating on its surface. The insulating coating is free of chromium and comprises plate-like particles of inorganic compound and a metal phosphate. The plate-like particles of inorganic compound are in the form of secondary particles, which are formed by aggregating primary particles, and present in an amount of not less than 0.1 parts by mass and not greater than 20 parts by mass, with respect to 100 parts by mass of the metal phosphate. The secondary particles have an average particle diameter of no less than 0.05 μm and no greater than 5 μm, and have a specific surface area of 1 to 80 m.sup.2/g. The primary particles have an aspect ratio of 50 to 1000. The electrical steel sheet has excellent heat resistance, corrosion resistance, appearance, and insulating properties.

A coating solution for forming an insulating film for a grain-oriented electrical steel sheet which contains one or more types of hydrous silicate powders having an average particle size of 2 μm or less, and one or more types of phosphoric acids and phosphates satisfying a relation of Σn.sub.iM.sub.i/ΣP.sub.i≤0.5, and satisfies (Formula 1).
1.5≤(Σn.sub.iM.sub.i+Σn′.sub.jM′.sub.j)/ΣP.sub.i≤15  (Formula 1)
(P represents the number of moles of phosphorus, M represents the number of moles of metal ions derived from the phosphate, n represents the valence of the metal ions derived from the phosphate, i represents the number of types of phosphates, M′ represents the number of moles of metal elements in the hydrous silicate, n′ represents the valence of the metal elements in the hydrous silicate, and j represents the number of types of hydrous silicates).

A coating solution for forming an insulating film for a grain-oriented electrical steel sheet which contains one or more types of hydrous silicate powders having an average particle size of 2 μm or less, and one or more types of phosphoric acids and phosphates satisfying a relation of Σn.sub.iM.sub.i/ΣP.sub.i≤0.5, and satisfies (Formula 1).
1.5≤(Σn.sub.iM.sub.i+Σn′.sub.jM′.sub.j)/ΣP.sub.i≤15  (Formula 1)
(P represents the number of moles of phosphorus, M represents the number of moles of metal ions derived from the phosphate, n represents the valence of the metal ions derived from the phosphate, i represents the number of types of phosphates, M′ represents the number of moles of metal elements in the hydrous silicate, n′ represents the valence of the metal elements in the hydrous silicate, and j represents the number of types of hydrous silicates).

Provided is a method for manufacturing a grain-oriented electrical steel sheet. The method comprises: hot rolling a slab to obtain a hot rolled sheet; subjecting the hot rolled sheet to hot band annealing as necessary; subjecting the hot rolled sheet to cold rolling; subjecting the cold rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component onto a surface of the decarburization annealed sheet and subjecting the decarburization annealed sheet to final annealing to form the forsterite film; and applying an insulating coating treatment liquid onto the final annealed sheet and subjecting the final annealed sheet to flattening annealing to form a tension-applying insulating coating. A difference in total tensions between one and opposite surfaces of the sheet is less than 0.5 MPa. A difference in tensions between the forsterite films in one and opposite surfaces of the sheet is 0.5 MPa or more.

Provided is a method for manufacturing a grain-oriented electrical steel sheet. The method comprises: hot rolling a slab to obtain a hot rolled sheet; subjecting the hot rolled sheet to hot band annealing as necessary; subjecting the hot rolled sheet to cold rolling; subjecting the cold rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component onto a surface of the decarburization annealed sheet and subjecting the decarburization annealed sheet to final annealing to form the forsterite film; and applying an insulating coating treatment liquid onto the final annealed sheet and subjecting the final annealed sheet to flattening annealing to form a tension-applying insulating coating. A difference in total tensions between one and opposite surfaces of the sheet is less than 0.5 MPa. A difference in tensions between the forsterite films in one and opposite surfaces of the sheet is 0.5 MPa or more.

Disclosed herein is a noise suppression sheet that includes a magnetic sheet and a first metal layer provided on one surface of the magnetic sheet. The first metal layer has a plurality of annular slits. The first metal layer is divided into a plurality of first areas surrounded respectively by the plurality of slits and a second area surrounding an entire periphery of each of the plurality of slits.