JP2003129196A - Grain-oriented silicon steel sheet with ultra-low core loss, and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grain-oriented silicon steel sheet with ultra-low core loss, having a ceramic tension film which has excellent adhesiveness and bending characteristics even after stress relief annealing at high temperature for a long time, and moreover does not cause degradation of the core loss worried in the stress relief annealing. SOLUTION: This silicon steel sheet has an extra-thin ceramic film consisting of crystallites having dominantly such orientations that a ratio of diffraction peak intensity (222)/(200) by X-ray diffraction can be 1.2 or higher, which is coated on the surface of the grain-oriented silicon steel sheet that has been finish-annealed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-low iron loss grain-oriented silicon steel sheet, and in coating the surface of a finish-annealed silicon steel sheet with a ceramic coating, in particular, effectively improving the adhesion of the coating. Therefore, the iron loss characteristics are further improved.

[0002]

2. Description of the Related Art In recent years, in the production of grain-oriented silicon steel sheet, TiN, TiO ₂ , Cr, etc. have been formed on the surface of a grain-oriented silicon steel sheet having no forsterite undercoat (hereinafter referred to as a filmless material).
N, TiC, Ti (C, N), Si ₃ N ₄ , SiO ₂ , AlN and Si (Si
-N-O-C) and other thin ceramic tension coatings have been proposed to produce ultra-low iron loss. See, for example, JP-A-11-131252.

[0003] A long-standing concern in such a manufacturing method is that the film has adhesiveness and bending property capable of withstanding strain relief annealing at high temperature for a long time, and there is no deterioration of iron loss which may occur during stress relief annealing. It is to effectively deposit a ceramic tension coating capable of achieving ultra-low iron loss.

The above-mentioned matters of concern have an adhesion and bending property of a coating capable of withstanding strain relief annealing at high temperature for a long time, and have achieved ultra-low iron loss without any deterioration of iron loss which may occur during strain relief annealing. Effectively depositing an ultra-thin ceramic tension coating that is possible.

That is, the grain-oriented silicon steel sheet is used as an iron core material of a transformer or an electric device, and the grain-oriented silicon steel sheet provided as a wound iron core transformer material is processed as a wound iron core by the customer and then Since strain relief annealing is performed at high temperature for a long time in order to remove the strain introduced at the time of processing, it is essential that excellent characteristics be maintained even after this strain relief annealing.

[0006]

However, when a thin ceramic tension coating is applied to the surface of the film-free material of the unidirectional silicon steel sheet, the ceramic coating has sufficient adhesion even after stress relief annealing at high temperature. It was extremely difficult to obtain stable. The main reason for this is that the deposited ceramic coating is more unstable than naturally occurring ceramics, so there is no coating between the deposited ceramic coating and the unidirectional silicon steel sheet during high temperature strain relief annealing. It is considered that the reaction progresses with the surface of the material and peeling easily occurs.

The present invention advantageously solves the above problems and has excellent adhesion and bending characteristics even after strain relief annealing at high temperature and for a long time, and there is a concern during such strain relief annealing. It is an object of the present invention to propose an ultra-low iron loss unidirectional silicon steel sheet having a ceramic tension coating which does not cause any deterioration of iron loss, together with its advantageous manufacturing method.

[0008]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, in order to improve the adhesion of the ceramic coating formed on the filmless material, the ceramic coating should be improved. It was found that it is important to control the structure of the ultra-thin ceramic coating for achieving excellent compatibility with the filmless material. Further, in controlling the structure of the ceramic coating, the X of the ceramic coating is controlled.
The (222) / (200) diffraction peak intensity ratio by line diffraction is
In particular, they have found that they can be a guideline for obtaining a coating film having excellent compatibility with a filmless material, and have completed the present invention.

That is, according to the invention, the surface of the finish-annealed unidirectional silicon steel sheet is (222) /
(200) An ultra-low iron loss unidirectional silicon steel sheet having an ultrathin ceramic coating which is crystalline with a preferential orientation of (200) diffraction peak intensity ratio of 1.2 or more.

Further, the present invention is an ultra-low iron loss unidirectional silicon steel sheet characterized in that an amorphous thin film and then an insulating coating are laminated on the above ultrathin ceramic coating.

The ultra-low iron loss unidirectional silicon steel sheet described above is obtained by forming an ultrathin ceramic coating on the surface of a finish annealed unidirectional silicon steel sheet, and then forming an amorphous film on the ultrathin ceramic coating. It can be advantageously manufactured by a method for manufacturing a unidirectional silicon steel sheet characterized by forming a thin film.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION First, the experimental results leading to the present invention will be described in detail below. C: 0.076 mass
%, Si: 3.35 mass%, Mn: 0.076 mass%, Se: 0.020 ma
ss%, Sb: 0.025 mass%, Al: 0.021 mass%, N: 0.00
A silicon steel continuous casting slab containing 70 mass% and Mo: 0.012 mass% and the balance being Fe and inevitable impurities.
After heat treatment at 1350 ° C for 4 hours, hot rolling is applied to the sheet thickness:
A 2.0 mm hot rolled sheet was used. The hot-rolled sheet was subjected to homogenizing annealing at 1050 ° C. for 2 minutes and then rolled twice with intermediate annealing at 1050 ° C. to obtain a final cold-rolled sheet having a thickness of 0.23 mm.

Then, after decarburizing and primary recrystallization annealing in wet H ₂ at 840 ° C., MgO (20 mass%), Al ₂ O ₃ (3
0mass%), Sr (OH) (10mass%), NiCl ₃ (15mass%), CaSiO ₃ (5
mass%), SiO ₂ (20mass%) composition, and then an annealing separator slurry is applied. Then, after annealing at 850 ℃ for 15 hours, the temperature is raised from 850 ℃ to 1100 ℃ at a rate of 12 ℃ / h. After developing the secondary recrystallized grains strongly integrated in the Goss orientation, a purification treatment was performed in dry H ₂ at 1200 ° C. to produce a silicon steel sheet (film-less material) having no forsterite coating.

On the surface of the film-free material thus obtained, a Hollow Cathode Discharge (HCD) method using a hollow cathode, an arc discharge method, a method of combining an electron beam with a Radio Frequency (EB + RF method), an electron beam is used.
Combined HCD method (EB + HCD method), chemical vapor deposition method (thermal CVD method), plasma chemical vapor deposition method (plasma CVD method)
And direct current magnetron sputter techniques to produce TiN ultra-thin ceramic coatings of 0.1 μm under various conditions.
It was formed to a thickness. Here, the ultra-thin ceramic coating formed on each film-free material is analyzed by thin-film X-ray (222)
The / (200) diffraction peak intensity ratio was measured.

Thereafter, a magnetron sputter method was used to form a SiNx coating on the ultrathin ceramic coating by 0.2 μm.
Formed thick. Furthermore, after forming an insulating coating of 0.8 μm thickness consisting mainly of colloidal silica and phosphate by baking, 800 ° C which is equivalent to high temperature strain relief annealing conditions.
Annealed in nitrogen for 3 hours.

The iron loss of the grain-oriented silicon steel sheet thus obtained was measured, and the coating adhesion was evaluated. The iron loss was evaluated as the degree of reduction with respect to the iron loss value of the filmless material. These evaluation results are summarized and shown in FIG.

As is clear from FIG. 1, when a TiN ceramic film has an ultrathin ceramic coating having a (222) / (200) diffraction peak intensity ratio by thin film X-ray of 1.2 or more, strain relief annealing at high temperature is carried out. It can be seen that in the subsequent unidirectional silicon steel sheet, the degree of reduction of iron loss was 0.11 W / kg or more, and a product with good coating adhesion was obtained. In particular, (22
It was also found that when the 2) / (200) diffraction peak intensity ratio is 4 or more, the degree of iron loss reduction increases significantly.

Here, (222) / (200
) A typical case of the diffraction peak intensity ratio is shown in FIG. That is, Fig. 2 shows the diffraction results by thin film X-rays of the ultra-thin ceramic coating made of TiN produced by the HCD method and the arc discharge method. It can be seen that the (222) / (200) diffraction peak intensity ratios of are completely different.

Although the relationship between the (222) / (200) diffraction peak intensity ratio and the iron loss has not been clarified, if the ultrathin ceramic coating has a good match with the silicon steel sheet matrix, the It is considered that the thin ceramic film epitaxially grows on the film-less material, the (222) / (200) diffraction peak intensity ratio becomes high, and the adhesion becomes good, resulting in a favorable effect on iron loss.

By the way, JCPDS (International
Center for Diffraction Data No. 38-1420), Ti
The diffraction peak intensity of N (222) is Int .: 72,
The (200) diffraction peak intensity of N is Int.:100.
Therefore, the (222) / (200) diffraction peak intensity ratio is 0.72, which is usually less than 1.2 specified in the present invention. Therefore, the (222) / (200) diffraction peak intensity ratio is 1.
In order to raise it to 2 or more, it is necessary to select a method for forming an ultrathin ceramic coating and then perform the treatment under appropriate conditions.

For example, as shown in FIG. 1, (222) /
To increase the (200) diffraction peak intensity ratio to 1.2 or higher, use HCD
Method, EB + HCD method, plasma CVD method and thermal CVD method, it is advantageous to perform the treatment under appropriate conditions.
In particular, in order to set the (222) / (200) diffraction peak intensity ratio to a range of 4 or more, it is preferable to form the film by the HCD method, especially the HCD method which gives a high bias voltage.

Next, the results of experiments conducted on the second layer coating formed on the ultrathin ceramic coating described above,
explain in detail. First, an ultra-thin ceramic coating of TiN was formed to a thickness of 0.1 μm on the filmless material of unidirectional silicon steel sheet that had been subjected to magnetic domain refinement treatment, using the HCD method. The (222) / (200) diffraction peak intensity ratio of this ultra-thin ceramic coating is
It was 4.8. On this ultrathin ceramic coating, a coating of (1) SiNx and (2) AlN is formed to a thickness of 0.2 μm using magnetron sputtering, and (3) Cr using the HCD method.
N, (4) TiO ₂ , (5) TiAlO ₂ , (6) MnCoNiN and (7) CrAlSi
A coating film of N is formed to a thickness of 0.1 to 0.15 μm, and an insulating coating film containing colloidal silica and phosphate as the main component is applied to the coating film with a thickness of 0.8 μm and baked at 800 ° C. Annealed in nitrogen for 3 hours. Table 1 shows the results of an examination of the magnetic properties and coating adhesion of the grain-oriented silicon steel sheet with a film thus obtained.

[0023]

[Table 1]

As is clear from Table 1, when both extremely low iron loss and good coating adhesion can be achieved, (1) Si
It can be seen that they are Nx, (2) AlN and (7) CrAlSiN. Among them, it is noted that SiNx has the most excellent characteristics. On the other hand, in the case of CrAlSiN, the iron loss is 0.55 to 0.64W /
It was found that the kg and the adhesiveness also slightly changed from peeling (Δ) to no peeling (◯).

Further, in the structural analysis of the second layer film by thin film X-ray diffraction, both super-iron loss and adhesion were achieved.
In the case of (1) SiNx and (7) CrAlSiN, it is noted that the structure of SiNx is amorphous and the structure of CrAlSiN is amorphous to crystalline. That is, it is noted that the second layer formed on the TiN ultrathin ceramic coating can achieve both super-iron loss and good adhesion when it has an amorphous structure rather than a crystalline structure.

The reason for this is not clearly understood, but the ultrathin ceramic coating of the first layer has a crystalline structure,
It is considered that when the second layer is laminated thereon as an amorphous structure, the second layer effectively acts as a diffusion barrier in the subsequent high temperature strain relief annealing.

Therefore, in order to verify whether the result of this consideration is valid, further, the structure of CrAlSiN of (7) is changed from amorphous to crystalline, and at the same time, the iron loss and the adhesion of the unidirectional silicon steel sheet are Since the value has also changed, detailed experiments were performed again for the CrAlSiN film of (7) with different contents of Cr, Al and Si. That is, when a CrAlSiN film was formed as the second layer, the film formation was performed under the same conditions as in the experiment whose results are shown in Table 1 above, except that the contents of Cr, Al and Si in the film were changed. to prepare a steel plate, which is the difference between the iron loss value and high temperature iron loss after stress relief in the membrane without material, as well as evaluating the iron loss reducing degree △ W _17/50 and coating adhesion, the second layer Thin film X-ray diffraction was performed. The results are summarized in Table 2.

[0028]

[Table 2]

As is clear from Table 2, the degree of reduction in iron loss _{ΔW 17/50} is 0.07 depending on the contents of Cr, Al and Si.
It varies from 4 to 0.151 W / kg, and it can be seen from the measurement by thin film X-ray diffraction that it becomes crystalline or amorphous depending on the contents of Cr, Al and Si. In particular, the component of (7-3) Cr _1.5 Al _1.0 Si _{2.0 has the} largest iron loss reduction degree _{ΔW 17/50} of 0.151 W / kg, and the measurement result by thin film X-ray diffraction in this case is amorphous. It is noted that Therefore, in this invention,
An amorphous coating is adopted as the second layer.

The determination of crystalline or amorphous by thin film X-ray diffraction was performed as follows. Here, as an example of the thin film X-ray diffraction, among the thin film X-ray diffraction results performed on the CrAlSiN film in Table 2, the crystalline case is shown in FIG. 3A, and the amorphous case is shown in FIG. ), Respectively. That is, in the thin film X-ray diffraction shown in FIG. 3A, a clear diffraction peak is recognized, which indicates that the film is crystalline. In addition, in CrN's JCPDS (card No. 11-0065),
(200) _CrN is 2.0680Å, Int .: 100, (220) _CrN is
1.4630Å, Int.:80 and AIN JCPDS (card
No. In 25-1496), (200) _{AI N} is 2.060 Å, Int .:
100, (220) _AIN 1.457 Å, Int .: 80, CrN
And the GD of the coating.
In S (Glow Discharge Spectroscopy) analysis, Cr, Al
Since Si and Si are detected, it is impossible to distinguish the difference between the peaks of CrN and AlN in the diffraction peak of FIG.

On the other hand, the result of the X-ray diffraction shown in FIG. 3 (b) is in a broad state without a clear diffraction peak,
Since it was impossible to determine the peak, the case where such an X-ray diffraction result was obtained was made amorphous. Therefore, the amorphous in the present invention means a case where a broad diffraction result without a clear diffraction peak as shown in FIG. 3B is obtained.

From the results shown in Table 2 and FIG. 3, as described above, when a film having an amorphous structure was formed as a second layer on a TiN ultrathin ceramic film, the ultra-low temperature was obtained even after high-temperature stress relief annealing. It can be seen that a unidirectional silicon steel sheet having iron loss and excellent adhesion can be obtained.

The reason why ultra-low iron loss and excellent adhesion can be obtained when a film having an amorphous structure is used as the second layer has not been clarified yet. 1
When a crystalline ultra-thin ceramic coating is formed on the layer and an amorphous film made of, for example, CrAlSiN or SiNx is laminated as the second layer, the second layer becomes ultra-thin in the subsequent stress relief annealing at high temperature. It is considered that this is because the ceramic film can effectively exert its function as a diffusion barrier.

The present invention discloses a new technical content relating to an ultrathin ceramic coating formed on a filmless material, based on the above experimental results, and is characterized in that the effect exerted by the present invention is extremely large. There is.

The respective constituent elements of the present invention will be described below.
Further details. In the present invention, it is preferable to use a unidirectional silicon steel sheet, especially a film-less material that has been subjected to a magnetic domain refining treatment, as a material to be coated. As this film-less material, manufactured by a conventionally known technique,
A unidirectional silicon steel plate can be used. Further, the filmless material can be further subjected to surface treatment, for example, pickling treatment, chemical polishing or electrolytic polishing treatment, but since any of these methods leads to cost increase, the filmless material is used as it is. Is preferable from the viewpoint of cost.

Next, it is advantageous that the ultrathin ceramic coating of the first layer, which is an essential condition of the present invention, is made of TiN from the viewpoint of adhesion with the filmless material. However, as shown in FIG. 1, if the (222) / (200) diffraction peak intensity ratio by the thin film X-ray diffraction of the ultrathin ceramic coating is 1.2 or more, there is no particular limitation on the material, and it is well known in the art. A known film such as a nitride ceramic film or a carbide ceramic film may be used. PVD, CVD, sprinkling, ion implantation, etc. can be used as the method for forming the ultrathin ceramic coating, but the (222) / (200) diffraction peak intensity ratio is
The HCD method is the most suitable because it can easily obtain 1.2 or higher.

Film forming conditions by the HCD method, especially (222)
/ (200) To increase the diffraction peak intensity ratio to 4 or above, use 200
It is recommended to heat at a temperature of ℃ or more, apply a bias voltage of -70 V or more with a high bias (preferably -100 to -300 V), and ionize the reaction gas at 1500 V, 65 mA.

Further, the thickness of the ultrathin ceramic coating is 0.
It should be about 01 to 0.3 μm. That is, in order to obtain the effect of the ultrathin ceramic coating described above, at least 0.01 μm
Thickness is required, while when the thickness exceeds 0.3 μm,
After all, the effect of the ultrathin ceramic coating described above, in particular, the function as an adhesion layer between the filmless material and the insulating coating is not exerted, and the cost is increased. More preferably, it is 0.005 to 0.3 μm.

Next, a second layer is formed on the ultrathin ceramic coating.
As the second layer, an amorphous film, specifically, an amorphous film made of CrAISiN or SiNx, acts as a diffusion barrier for the second layer in the subsequent high temperature strain relief annealing. It is advantageous to make the most of it. The definition of amorphous in this case is as described above. As the amorphous film, in addition to CrAISiN and SiNx, TiAlN, TiCrSiN, TiCr
Amorphous coatings such as nitrides of various metals such as AlSiN can be employed.

The thickness of the amorphous coating is 0.005 to 0.3.
It is about μm. That is, the thickness of the amorphous coating is 0.005
If it is less than μm, the effect as a barrier is small, while 0.3
If it exceeds μm, the cost is increased and it becomes an economical problem.

Here, the amorphous film can be formed by using the HCD method or the magnetron sputtering method, but in order to make the obtained film amorphous, various kinds of metals are contained. Note that a nitride (for example, containing Cr, Al, Si, Ti, B, etc.) is deposited.

The steel sheet thus coated is further coated with a known insulating coating, preferably in a thickness of 0.3 to 1.5 μm to obtain a product plate.

[0043]

Example: C: 0.073 mass%, Si: 3.42 mass%, Mn: 0.
072 mass%, Se: 0.020 mass%, Sb: 0.025 mass%, A
l: 0.020 mass%, Mo: 0.012 mass% and N: 0.0071m
A silicon steel slab containing ass% and the balance of which is substantially composed of iron and unavoidable impurities is heated at 1340 ° C. for 3 hours, hot-rolled, and then subjected to intermediate annealing at 1050 ° C. 2
Cold rolling was performed twice to obtain a final cold-rolled slope with a thickness of 0.23 mm. After that, at a width of 20 mm at an interval of 4 mm in a direction substantially perpendicular to the rolling direction
0 [mu] m and depth: forming a groove of 20 [mu] m, then subjected to magnetic domain refining treatment, carried out decarburization annealing in a wet hydrogen of 840 ° C., and then the steel slope _{surface, CaSiO 3: 25mass%, A1} 2 0 ₃ : 10
mass%, MgO: 45mass%, SiO 2: 15mass%, AICl 3: 3
mass% and Sr (OH): After applying an annealing separator containing 2 mass% as the main component, hold at 850 ° C for 15 hours, then at 12 ° C / h
Then, the temperature was raised to 1050 ° C. to preferentially grow secondary recrystallized grains in the Goss orientation, and then purification annealing was performed in dry hydrogen at 1200 ° C.

Then, a TiN ceramic tension coating of 0.1 μm was formed as the first layer on this filmless material using (A) HCD method.
Overlaid with thick. (B) Apply 0.15 TiN ceramic tension coating using thermal CVD method.
Deposited to a thickness of μm. Then, as the second layer, (a) a SiNx film of 0.15 is formed by using the magnetron sputtering method.
Deposited to a thickness of μm. (b) The HCD method was used to deposit a CrAlSiN film to a thickness of 0.15 μm.

The film forming conditions are as follows. (A) HCD method: A film was formed at a bias voltage of -150 V, an ionization voltage of 1500 V and 65 mA at 40 V, 500 A and 250 ° C. (B) Thermal CVD method: In a TiCl ₄ + H ₂ + N ₂ atmosphere at 950 ℃,
A 10 minute CVD reaction was performed. (a) Magnetron-sputtering method: Sputtering was performed at 15 KW using a Fellow Si target. (b) HCD method: A film was formed at 20 V and 250 A.

Next, an insulating coating containing colloidal silica and phosphate as the main components was formed by coating and baking, and then strain relief annealing was carried out at 800 ° C. for 3 hours in a nitrogen atmosphere.
The degree of improvement in iron loss of the product thus obtained (△ W _17/50 )
Table 3 shows the results of the evaluation of the film adhesion and the film adhesion.

[0047]

[Table 3]

As is clear from Table 3, the first layer applied to the film-less material of the unidirectional silicon steel sheet was an ultrathin ceramic coating having a (222) / (200) diffraction peak intensity ratio of 1.2 or more, and the second It is noted that by forming the layer as an amorphous coating, among the magnetic properties of the unidirectional silicon steel sheet, the magnetic flux density is the same, but the iron loss is significantly improved to 0.13 W / kg. Also, when bending 180 ° on a round bar with a diameter of 15 mm,
It can be seen that the coating does not peel off and the coating has excellent adhesion.

[0049]

According to the present invention, the coating film formed on the surface of the finish-annealed unidirectional silicon steel sheet has excellent adhesion and bending characteristics even after strain relief annealing at high temperature for a long time, Moreover, since the deterioration of iron loss, which is a concern during such stress relief annealing, is not caused, it is possible to stabilize the ultra-low iron loss unidirectional silicon steel sheet having excellent iron loss characteristics even after high temperature and long time stress relief annealing. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the degree of reduction in iron loss and the adhesion of a coating, and the (222) / (200) diffraction peak intensity ratio of the coating measured by thin film X-ray diffraction.

FIG. 2 is a diagram showing the results of thin film X-ray diffraction measurement of an ultrathin ceramic coating.

FIG. 3 is a diagram showing a result of thin film X-ray diffraction measurement of a CrAlSiN film.

Continued front page    F-term (reference) 4K026 AA03 AA22 BA01 BA08 BA12                       BB10 CA16 CA18 CA23 CA27                       CA41 DA02 EB11                 4K029 AA02 BA58 BB02 BB08 BB10                       CA03 CA05 DC39 DD05 FA06                       GA01 GA03

Claims (3)

[Claims] 1. An ultrathin ceramic coating, which is crystalline, is preferentially oriented so that the (222) / (200) diffraction peak intensity ratio by X-ray diffraction is 1.2 or more on the surface of a finish-annealed unidirectional silicon steel sheet. An ultra-low iron loss unidirectional silicon steel sheet having. 2. An ultra-low iron loss unidirectional silicon steel sheet, which is obtained by laminating an amorphous thin film and then an insulating coating on the ultrathin ceramic coating according to claim 1. 3. An ultrathin ceramic coating is formed on the surface of a finish-annealed unidirectional silicon steel sheet, and then an amorphous thin film is formed on the ultrathin ceramic coating. Method for manufacturing grain-oriented silicon steel sheet.