JPH04272166A - Manufacture of ultralow core loss grain-oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To regulate the core loss in a grain oriented silicon steel sheet to an ultra low one exceeding that in the conventional tension film forming material. CONSTITUTION:Oxides on the surface of a grain-oriented silicon steel sheet finished with finish annealing are removed. After that, on the surface of the steel sheet subjected to grinding, the thin film of one kind of high permeability alloy selected from Fe-Si allay, Fe-Al alloy and Fe-Si-Al alloy is formed, and after that, it is coated with an insulating film.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION This invention relates to a method for producing grain-oriented silicon steel sheets, and the object thereof is to propose a method for advantageously improving magnetic properties, particularly iron loss properties.

0002

[Prior Art] As is well known, unidirectional silicon steel sheets have secondary recrystallized grains in Goss orientation (110) (0
01], it is highly integrated and is mainly used as the iron core of transformers and other electrical equipment, and the product has high magnetic flux density (represented by B8) as an electric and magnetic property.
Low iron loss (W17/50 value) is required. This unidirectional silicon steel is manufactured through a wide variety of complicated processes, but recently, the surface of the unidirectional silicon steel plate after final annealing is irradiated with a laser in a direction almost perpendicular to the rolling direction to create local micro-strains. It was proposed that the magnetic domain be subdivided by introducing a method to reduce iron loss. (Tokuko Showa 57
-2252, Japanese Patent Publication No. 57-53419, and Japanese Patent Publication No. 58-26406). This magnetic domain refining technology is effective for transformer materials for laminated cores that are not subjected to strain relief annealing. However, for core transformer materials that are subjected to strain relief annealing, local microscopic Since the strain is released by the annealing treatment and the magnetic domain width becomes wider, there is a drawback that the laser irradiation effect is lost.

[0003] On the other hand, earlier than this, Special Publication No. 52-24499
In the publication, ultra-low iron loss is achieved by mirror-finishing the surface of a unidirectional silicon steel sheet after finish annealing, or by coating and baking metal plating or an insulating film on the mirror-finished surface. A method for manufacturing unidirectional silicon steel sheets has been proposed. However, this method of improving iron loss through mirror finishing does not make a sufficient contribution to reducing iron loss in spite of the significant increase in cost and is not suitable for use in the process.
In particular, after finishing the mirror finish, we apply and bake the indispensable insulation coating.
Furthermore, it has not been adopted in current manufacturing processes because it has problems with adhesion to steel plates after being subjected to strain relief annealing at a high temperature of 600° C. or higher for a long time. Japanese Patent Publication No. 56-4150 also proposes a method in which a steel plate surface is mirror-finished and then an oxide-based ceramic thin film is vapor-deposited. However, this method also has 600
If high-temperature annealing is applied above ℃, the steel sheet and the ceramic layer will separate, so it cannot be used in the actual manufacturing process.

[0004] Therefore, the inventors proposed the
7, Special Publication No. 63-32850 and Special Publication No. 63-32
As disclosed in various publications such as No. 849, after removing the forsterite coating on the surface of the finish annealed unidirectional silicon steel sheet, polishing treatment was performed, and then ion plating, CVD (Chemical Vapor Deposition)
position) or by ion implantation, Ti, Zr, Hf, V, Nb, Ta, Mn,
A tensile coating consisting of one or more and four or less selected from nitrides and/or carbides of Cr, Mo, W, Co, Ni, Al, B, and Si is formed, or an insulating coating is further formed on this tensile coating. We have previously proposed a method for obtaining ultra-low iron loss unidirectional silicon steel sheets with excellent thermal stability of magnetic properties by applying layers of adhesive coatings and baking layers. These methods can provide ultra-low iron loss characteristics, but in view of the current situation where the demand for reducing power loss as the highest priority from the standpoint of energy conservation is increasing, it is still necessary to further reduce iron loss. It is strongly desired.

[0005]

[Problem to be Solved by the Invention] It is an object of the present invention to obtain characteristics that outweigh the disadvantage of the increased cost required for the polishing process by more advantageously bringing out the effect of improving iron loss characteristics through the polishing process, including the above-mentioned mirror finishing. It is an object of the present invention to advantageously achieve an ultra-low core loss that exceeds that of the tensile film forming material of the present invention by fundamentally improving the film.

[0006]

[Means for Solving the Problems] As a result of various experiments and studies, the inventors have found that Fe-Si alloys, Fe-Al alloys, and Fe-Si-Al alloys are particularly advantageous as coatings. I found it. Such alloys, including the Fe-Si-Al alloy known as "Sendust alloy", are alloys with high magnetic permeability and high magnetic flux density, and are capable of obtaining good magnetic properties such as reduced hysteresis loss. be. Therefore, a thin film of such an alloy is removed by removing oxides on the surface of the steel plate.
It has been found that by coating the surface of a polished unidirectional silicon steel sheet, it is possible to further improve magnetic flux density and achieve ultra-low iron loss.

The present invention is based on the above knowledge. That is, this invention removes oxides on the surface of a finish-annealed unidirectional silicon steel sheet, and then applies an Fe-Si alloy onto the polished surface of the steel sheet by ion plating, CVD, or ion implantation. ,
An ultra-low iron loss unidirectional silicon steel sheet characterized by being coated with a thin film of one kind of high magnetic permeability alloy selected from Fe-Al alloy and Fe-Si-Al alloy, and then applying an insulating coating. This is the manufacturing method.

[0008]

[Operation] The explanation will be as follows according to a specific experimental example from which the present invention was derived. C: 0.044 wt%
(hereinafter simply shown in %), Si: 3.38%, Mn: 0.
070%, Se: 0.020%, Sb: 0.023
% and Mo: 0.012%, with the remainder being substantially Fe, at 1340°C for 30 minutes.
After heating for a period of time, hot rolling was performed to obtain a hot rolled sheet having a thickness of 2.4 mm. Then, after homogenization annealing at 960 °C for 1 minute,
Cold rolling was performed twice with intermediate annealing for 1.5 minutes at 950° C. to obtain a final cold rolled sheet having a thickness of 0.23 mm. Then, after decarburization and primary recrystallization annealing in wet hydrogen at 820°C, an annealing separator mainly composed of MnO was applied to the surface of the steel sheet, and secondary recrystallization annealing was performed at 850°C for 50 hours. Purification annealing was performed for 8 hours in dry hydrogen at 1230°C. Thereafter, oxides on the surface of the steel plate were removed, and the surface of the steel plate was polished to a mirror-like finish with a center line average roughness of 0.2 μm. After that, ion plating (
Accelerating voltage: 50 V, current 500 A), four types of coatings were formed: ■TiN (thickness: 1.5 μm) ■Fe-Si alloy (thickness: 1.5 μm) ■Fe-A
l alloy (thickness: 1.5 μm) ■After each film is coated with Fe-Si-Al alloy (thickness: 1.5 μm), an insulating film containing phosphate and colloidal silica as main components is applied to the surface. was created. After that, strain relief annealing (800
°C for 2 hours). Table 1 summarizes the results of measuring the magnetic properties, space factor, and interlayer resistance of these steel plates.

[0009]

From the same table, when a TiN film is formed as in the conventional case, B8 is 1.91T and W17/50 is 0.70.
W/kg, whereas according to this invention Fe-
When Si alloy, Fe-Al alloy, and Fe-Si-Al alloy films are respectively formed, B8 is 1.92 to 1.9.
While maintaining the high magnetic flux density of 3T, W17/50
It is noteworthy that the core loss of 0.65 to 0.62 W/kg has been shown to be extremely low, and the space factor of TiN is 97%, whereas that of Fe
It is noteworthy that good results of 98.3 to 98.5% and 1.3 to 1.5% were obtained when Si alloy, Fe-Al alloy, and Fe-Si-Al alloy films were respectively formed. be done.

[0011] As described above, the reason why magnetic properties, especially iron loss properties, are improved by forming a thin film of high magnetic permeability alloys such as Fe-Si alloy, Fe-Al alloy, and Fe-Si-Al alloy is not clear. However, it is thought that the following is true. That is, as disclosed in the above-mentioned Japanese Patent Publication No. 63-54767, Japanese Patent Publication No. 63-32850, and Japanese Patent Publication No. 63-32849, when a ceramic coating is formed on a silicon steel plate, such ceramic coating Whereas it is completely impossible for the film to act as a magnetic film,
Fe-Si alloy, Fe-Al alloy and F according to the present invention
In the case of a high magnetic permeability alloy thin film called e-Si-Al alloy, the thin film itself can act as a magnetic film, and the characteristics of the magnetic film can be effectively added to the characteristics of the silicon steel sheet. It is considered that the magnetic properties become even better and it becomes possible to improve the space factor.

[0012] Such an iron-based high permeability alloy coating is applied to a unidirectional silicon steel plate (thickness 0.0
5 to 0.35 mm) by a commonly known method, and then polished, followed by ion plating, C
Deposited by VD or ion implantation. Thereafter, an insulating coating, for example, an insulating coating mainly composed of phosphate and colloidal silica, is formed.

The composition of the high magnetic permeability alloy film is preferably as follows. In Fe-Si alloys, the Si content is 3-13%
, more preferably 4 to 10%, with the balance being Fe, Fe-
In an Al alloy, the Al content is 1 to 17%, more preferably 2 to 16%, with the balance being Fe, and in the Fe-Si-Al alloy, the Si content is 3 to 13%, more preferably 4 to 10%.
%, Al content is 1 to 17%, more preferably 2 to 16%
% with the remainder being Fe.

The film thickness of this high magnetic permeability alloy film is 0.05
If it is less than 20 μm, it will be difficult to manufacture it industrially stably, while if it exceeds 20 μm, there will be an inconvenience of increased costs due to coating.
Approximately 5 to 20 μm is preferable.

The thin film may be formed by ion plating, CVD or ion implantation on the surface of the silicon steel plate so as to have the above composition.

[0016]

[Example] Two types with different component compositions A) C: 0.013%, Si: 3.41%, Al: 0
．． 023%, N: 0.0082%, Se: 0.021
%, Mo: 0.012%, Sb: 0.019% and Sn: 0.08%, the remainder being substantially Fe and B) C: 0.044%, Si: 3.36%. , S
e: 0.024%, Sb: 0.023% and Mo:
A silicon steel hot-rolled plate (thickness 2.4 mm) containing 0.015% Fe and the remainder being substantially Fe was heated to 9.
Cold rolling was performed twice with intermediate annealing for 3 minutes at 80° C. to obtain a final cold rolled sheet having a thickness of 0.23 mm. After that, 8
After decarburization and primary recrystallization annealing in wet hydrogen at 30°C, the temperature was raised from 850°C to 1050°C at a heating rate of 4°C/h to develop Goss-oriented secondary recrystallized grains. , 1230
Purification annealing was performed in dry hydrogen for 10 hours at °C. Thereafter, the oxide film on the surface of the steel plate was removed, and the surface was polished to a mirror-like finish with a center line average roughness of 0.1 μm. Thereafter, a Fe-Si alloy, Fe-Al alloy, or Fe-Si-Al alloy film was formed by ion plating, CVD, or ion implantation. After that, an insulating coating mainly composed of phosphate and colloidal silica was applied. Table 2 summarizes the results of measuring the magnetic properties, space factors, and interlayer resistance of the various steel plates thus obtained. In the table, the method of formation is marked *, CVD, **, ion plating, and ***, ion implantation.

[0017]

[0018]

[Effect of the invention] The method for producing an ultra-low core loss unidirectional silicon steel sheet of the present invention involves removing oxides on the surface of a finish annealed unidirectional silicon steel sheet, and then polishing the surface of the steel sheet. A thin film of a high magnetic permeability alloy selected from Fe-Si alloy, Fe-Al alloy, and Fe-Si-Al alloy is formed on the top by ion plating, CVD, or ion implantation, and then insulation is applied. By applying a coating, it is possible to achieve ultra-low iron loss that exceeds that of conventional tension coating forming materials.

Claims (1)

[Claims] 1. After removing oxides on the surface of a finish-annealed unidirectional silicon steel sheet, a Fe-Si alloy is formed on the polished surface of the steel sheet by ion plating, CVD, or ion implantation. , Fe-Al
A method for producing an ultra-low core loss unidirectional silicon steel sheet, which comprises depositing a thin film of one type of high magnetic permeability alloy selected from alloys and Fe-Si-Al alloys, and then applying an insulating coating.