JPH0151043B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a coating having good insulation properties, corrosion resistance, tension imparting properties, and bending adhesion properties on electromagnetic ribbons used as laminated iron core materials for electrical equipment. .

Due to the recent rise in energy costs, there is a need to further reduce the energy and iron loss consumed by the iron core of electrical equipment. For this reason, iron-based amorphous alloy ribbons are attracting attention as soft magnetic materials. In particular, it contains 70at% or more of Fe, and contains vitrifying elements such as B, Si, P, and C, or
A, Va group elements such as Ti, Zr and sometimes Nb and Co
Amorphous alloys containing iron have much lower iron loss than conventional materials, and their saturation magnetic flux density is about 1.5T or higher, which is not that low. It is being considered for application as a material. In addition, recently, similar to amorphous alloy ribbons, 2 to 8 wt%
High-silicon steel sheets containing Si have been created and are attracting attention as new soft magnetic materials. especially
At a composition around 6.5wt%Si-Fe, magnetostriction almost disappears, so if a suitable texture such as a (100) cubic structure is formed by high-temperature annealing, the iron content is significantly lower than that of conventional materials. Loss characteristics can now be obtained. In order for such a new material to be actually applied as a laminated iron core material, the ribbon itself must have excellent properties such as magnetic permeability and iron loss, and a good film must be formed on the surface of the ribbon. I need to be there. The properties required for this coating vary depending on the type of equipment used, but in general, it is desirable to have insulation properties (high electrical resistance to prevent interlayer short circuits and interlayer eddy current losses. Especially for large transformers, large Laminated iron cores and wound iron cores are essential for rotating machines.) Bending adhesion (It is desirable that the coating does not peel off from the iron surface when bent, that is, the minimum bending radius without peeling is smaller. Corrosion resistance (Rust is not desirable even in electromagnetic materials.) Furthermore, heat resistance (when performing strain relief annealing after punching, shearing, or winding) It is important that annealing does not cause deterioration or peeling of the material.This is especially important when used in the wound core of a power distribution transformer.

In addition, tension imparting properties (applying tension to the base steel due to the difference in thermal expansion between the coating and the base steel. During core forming, tightening pressure and compressive force are applied to the steel plate surface in the longitudinal direction, and λ100 is generally positive. When it has a large value, this causes property deterioration (iron loss and magnetostrictive vibration), but if tension is applied in advance by the coating, property deterioration due to this pressure can be reduced and prevented. ) is also desirable for materials where magnetostriction cannot be ignored.

Today, silicon steel sheets containing up to about 3 wt% Si are used in large quantities as laminated iron core materials for electrical equipment. Among these, grain-oriented silicon steel sheets, which have a texture accumulated in the (110) <001> direction, are used for the iron core of transformers, etc., where magnetic flux is applied only in one direction, and they do not necessarily have a specific texture. Non-oriented silicon steel sheets, which exhibit suitable properties in all directions, are used for iron cores of rotating equipment, etc. In grain-oriented silicon steel sheets, the surface oxide film and forsterite (2MgO・SiO ₂ ) produced by high-temperature annealing at 1000°C or higher after applying a release agent containing MgO as the main component causes basic damage. In order to form an insulating film and add tensile strength and corrosion resistance, a heat-resistant phosphate-based coating liquid is baked on. As a result, the interlayer insulation resistance (e.g.
When measured by the method specified in JISC2550) 50 ~
200 (Ω-cm ² / sheet). Furthermore, even if strain relief annealing is performed at approximately 850°C, the adhesion does not deteriorate.

On the other hand, for non-directional steel sheets, a phosphate-based inorganic coating or a coating liquid containing a resin component is baked directly onto the base steel surface. In this case, heat resistance is generally inferior.

The coating formation methods known as prior art described above are not only unsuitable for the amorphous alloy ribbon or rapidly solidified high-silicon steel ribbon that is the object of the present invention, but also difficult to implement. There are quite a few points.
That is, in order to form forsterite as a base film, high-temperature annealing of 1000° C. or higher is required, but this annealing is not possible for amorphous alloys due to crystallization. In addition, as shown in Japanese Patent Application No. 164693-1987, for high-silicon steel quenched ribbon,
(100) In order to have a highly developed in-plane cubic structure and excellent magnetic properties, the bare iron surface of the surface is exposed to the atmosphere and annealed under a vacuum of 10 ^-2 to ^{10 -7} Torr. However, it is difficult to form the above-mentioned forsterite in such annealing. Also, after this vacuum annealing,
After oxidizing the surface and applying MgO,
Forsterite can be formed by high-temperature annealing, but this is not practical because the manufacturing cost increases.

The inventors conducted various experiments in order to form coatings with good properties on amorphous alloy ribbons and high-silicon steel quenched ribbons. The present invention was completed based on the discovery that a thin ceramic film having good properties could be formed by applying a ceramic thin film by chemical vapor deposition or sputtering.

In this invention, the electromagnetic material on which the film is formed is an amorphous alloy ribbon containing 70 at% or more of Fe and 2 to 8 wt% of Si produced by ultra-quenching from a liquid. High-silicon steel quenched ribbon will be used. Amorphous alloy ribbons containing 70 at% or more Fe usually have a saturation magnetic flux density of about 1.5 T or more at room temperature, so they can be used as core materials for power transformers and the like. These are known to have a composition expressed as Fe _a X _b Y _c (subscripts are atomic %), where a75, b
+c25, X=one or more of Co, Ni, Mn, Cu, and Cr; Y=one or more of B, Si, C, P, and Ge. _{Typically , Fe81B13Si4C2 ,}
It is known that Fe ₇₈ B ₂₀ P ₁ Ge ₁ , Fe ₇₈ Co ₃ Si ₅ B ₁₄ , and the like have a relatively large saturation magnetic flux density, are thermally stable, and have excellent magnetic properties. In addition to the above-mentioned amorphous alloy ribbon, this invention also uses Fe _a Co _b (Ti, Zr) _c (where a>70, b<15,
An amorphous alloy ribbon having the formula 5<c<20) can be used.

On the other hand, high-silicon steel quenched ribbons containing 2 to 8 wt% Si, especially quenched ribbons with in-plane non-directional structures accumulated in the (100) [OKl] orientation, have excellent excitation and iron loss characteristics. It can be used as a core material not only for power transformers but also for rotating machines.

In this invention, SiO ₂ ,
MgO _{, Al2O3} , _TiO2 , _Ce2O3 , _{SrO2 , Ta2O5 ,}
Thin film coatings of corrosion-resistant ceramics such as ThO ₂ and ZrO ₂ are formed by vacuum deposition, chemical vapor deposition or sputtering.

In vacuum evaporation, the ceramic is heated by electron beam irradiation or the like under a vacuum of about 10 ^-2 or higher to form a ceramic thin film on the surface of the substrate (thin ribbon). A good thin film can be formed on the substrate (thin ribbon) without particular heating, but generally, if it is heated to 200 to 400°C, a thin film with higher density and better adhesion will be formed. In this case, a crystalline high-silicon steel ribbon can be heated to any temperature to deposit ceramics, but in the case of an amorphous alloy ribbon, the heating temperature is lower than the crystallization temperature of the alloy. It is necessary to do so. The amorphous alloy of _Fe75-85 (B, Si, C, P) _25-15 has a crystallization temperature ranging _from 300 to ₅₀₀ °C. In general, amorphous alloy ribbons have poor magnetic properties when they are produced by quenching from a liquid, so they are annealed at a crystallization temperature above the Curie point to improve their properties. At this time, when a magnetic field is applied in the longitudinal direction of the ribbon to cool it, uniaxial anisotropy occurs in the longitudinal direction, and particularly excellent magnetic properties can be obtained in the longitudinal direction.

In the present invention, in the case of an amorphous alloy ribbon, it is desirable that the heat treatment for improving magnetism and the formation of the ceramic thin film be performed simultaneously in the same process.

In addition, the inventors found that when applying tension in the longitudinal direction of the ribbon during continuous ceramic deposition in vacuum evaporation, the magnetic properties of the ribbon in the final product improve, especially compressive stress due to curvature etc. It has been found that even in such cases, deterioration of magnetic properties is reduced.

Figure 1 shows an example of the characteristics. SiO ₂ and MgO were deposited on a 25 μm thick Fe ₈₀ B ₂₀ amorphous ribbon prepared by a single roll method in a vacuum chamber at 10 ⁻² Torr by electron beam irradiation heating. At this time, the ribbon was heated to 290°C. After this, after further annealing in a magnetic field of 50 Oe at 325° C., the Hc value (DC, Bm = 1.2 T) was measured in a flat plate shape and in a toroidal shape with various curvatures. As shown in Figure 1, as the diameter of the toroid is reduced, the Hc value deteriorates and the merits of the material as a soft magnetic material are lost. This is thought to be due to compressive force being generated locally on the plate due to the curvature.
This is particularly noticeable in materials like this example, which have a high Fe content and a large positive value of magnetostriction λ100. However, as shown in Figure 1, SiO ₂ or MgO is
When deposited, the degradation of Hc due to curvature is much smaller. The coefficient of thermal expansion of Fe ₈₀ B ₂₀ amorphous ribbon is approximately
10 × 10 ^-6 K ^-1 , whereas that of SiO ₂ and MgO is about 1 × 10 ^-6 K ^-1 or less, so the difference in thermal expansion coefficient is caused by cooling after heating during vapor deposition. tension is exerted on the ribbon. This is thought to have alleviated the compressive force caused by the curvature and suppressed the deterioration of the Hc value as shown in Figure 1.

Furthermore, a similar example of 4.5wt% silicon steel is shown in the second example.
As shown in the figure. A silicon steel ribbon containing 4.5wt%Si prepared by the twin roll method was continuously annealed at 1000℃. The surface roughness of this ribbon was an average roughness Ra=1.0 μm. This thin film is coated with SiO ₂ in the same way as in Figure 1.
MgO was deposited, and the Hc value (DC, Bm=1.2T) was measured in a toroidal shape with various curvatures.
As shown in FIG. 2, the Hc value deteriorates due to curvature, but this deterioration is reduced in the case of SiO ₂ or MgO deposited.

Suppressing the deterioration of ceramic properties by forming a ceramic thin film as described above has a great practical effect.

The amorphous alloys and high-silicon steel quenched ribbons that are the subject of this invention are usually wound into a toroidal shape to form an iron core and used in power transformers and electronic devices, so if the magnetic properties are significantly degraded due to curvature, , it is flat and has excellent properties, but cannot be put to practical use. This invention has the effect of suppressing deterioration due to curvature, and therefore sufficiently improves the characteristics particularly in actual machines.

Next, Figure 3 shows the iron loss measured using the same amorphous ribbon sample in a flat plate shape and a 35 mmφ toroidal shape after vacuum-depositing SiO ₂ to a thickness of 0.8 μm.
W _12/50 (Iron loss at 50Hz with 1.2T excitation) is shown. In vacuum evaporation, there are cases where the ribbon is not heated and cases where the ribbon is not heated.
SiO ₂ was vapor-deposited while applying tension in each case of heating to 350°C, and then at 350°C.
Annealing was performed in a magnetic field of 50 Oe. If the deposition is performed under tension, the iron loss will be lowered. This tendency is particularly noticeable when measuring a curved ribbon. The effect of such additional tension becomes apparent from a tension of approximately 0.5 Kg/mm ² . Therefore, in the present invention, the tension applied during vapor deposition is set to 0.5 Kg/mm ² or more.

Next, the plate was made directly from molten steel using the twin roll method.
A silicon steel ribbon with a thickness of 120 μm is heated at 1140℃ to approx.
After annealing for 20 minutes in a vacuum of 10 ^-2 Torr, MgO was deposited in the same vacuum chamber. During this deposition, tension was applied in the longitudinal direction of the ribbon. Figure 4 shows the iron loss values of these thin strips in a flat plate shape and a 35 mmφ toroidal shape. When made toroidal, the iron loss value deteriorates. This tendency is more pronounced for low-Si materials with higher magnetostriction, but this deterioration can be alleviated by applying tension during deposition. This tension becomes effective at 0.5Kg/mm ² or more.

As can be seen from the results of the above test examples, it is more preferable to apply a ceramic thin film coating to the surface of the ribbon by vacuum deposition because it alleviates magnetic deterioration during application.

Ceramics have high insulation properties and high corrosion resistance, so if the surface of the ribbon is covered with a sufficiently thick ceramic thin film, insulation and corrosion resistance will inevitably be satisfied.

In this invention, when ceramics are coated as a thin film with a thickness of 0.1 μm or more, approximately 10
An interlayer electrical insulation resistance of (Ω-cm ² /sheet) or more was obtained. Further, if the thickness is 0.1 μm or more, sufficient corrosion resistance can be obtained as a core material for electrical equipment. Therefore, in this invention, the thickness of the ceramic thin film is set to 0.1 μm or more. However, on the other hand, if the thickness of the ceramic thin film becomes 3 μm or more, it is preferable in terms of magnetism, insulation, and corrosion resistance, but the non-magnetic portion of the finished product ribbon increases and the space factor deteriorates, which is disadvantageous in terms of application. At the same time, the bending adhesion deteriorates, and peeling occurs, for example, at a curvature of about 20 mmφ. Further, as a matter of course, vapor deposition of 3 μm or more requires a long time and is not preferred from an industrial perspective. Therefore, in this invention, the thickness of the ceramic thin film is set to 3 μm or less.

Next, in the present invention, the ceramic thin film may be applied by chemical vapor deposition. Typically
Vapors of metal chlorides such as AlCl ₃ , SiCl ₄ , ZrCl ₄
A gas such as H ₂ or Co ₂ is applied to the ribbon as a carrier to form a ceramic thin film of Al ₂ O ₃ , SiO ₂ , ZrO ₂ or the like on its surface. In this case, a thin strip is usually used.
Heating to 700-1050°C will form a thin film with higher density and better adhesion. This method is not suitable for amorphous alloy ribbons that cannot be heated at high temperatures. This method can be applied to high-silicon steel ribbons, and as described above, if tension is applied during thin film formation, deterioration due to magnetic curvature is alleviated.

Further, in the present invention, good results can be obtained even when sputtering is used to form a thin film. In this method, ceramics such as SiO ₂ are usually sputtered with argon or the like under vacuum to form a thin film on the surface of the ribbon. In this case, as in the case of vacuum deposition, it is preferable to heat the ribbon during sputtering and at the same time apply a tension of 0.5 kg/mm ² or more.

Amorphous alloy ribbons and high silicone alloys are produced using the vacuum deposition, chemical vapor deposition, and sputtering methods described above to form coatings consisting of ceramic thin films with corrosion resistance, insulation properties, tension imparting properties, and good bending adhesion. Raw steel ribbon can be used as a core material for electrical equipment in its original state. In particular, the product of the present invention, which has excellent tension imparting properties, exhibits its properties when applied to wound core iron core materials.

Furthermore, depending on the application, even higher levels of insulation, corrosion resistance, or tension imparting properties may be required. In such cases, after forming a ceramic thin film, a coating liquid containing phosphate as the main component is applied and baked at a temperature of about 800°C to form a tension-applied top coat. is good. This tensioning coating further improves the magnetostrictive-compressive properties of the ribbon, as is known in the art.

The thus coated ribbon is sheared and punched and assembled into a core. The coating of this invention can sufficiently withstand strain relief annealing at about 800°C.

Examples will be described below.

Example 1 An 85 μm thick 6.4wt% Si-Fe quenched ribbon and a 25 μm thick amorphous quenched ribbon (Fe ₈₁ B _13.5 Si _3.5 C ₂ ) were each treated with mild H ₂ to remove surface oxides. After being subjected to SO ₄ pickling, a mixed thin film of 2 μm of SiO ₂ and Al ₂ O ₃ was formed on the ribbon surface by sputtering.
Sputtering was performed using argon ions at a pressure of 3×10 ⁻⁴ Torr.

This thin film did not peel off even after being bent to a diameter of 10 mm. Also, the interlayer insulation resistance is 70 to 100Ω・cm ² /
It was hot. Furthermore, this thin strip was heated at 80% humidity and 35°C.
No corrosion was observed after exposure to the air for 30 days.

[Brief explanation of drawings]

Figures 1 and 2 are graphs showing how Hc deteriorates under various curvatures, and Figures 3 and 4 are graphs of the relationship between added tension during vapor deposition and iron loss.

Claims (1)

[Scope of Claims] 1. The surface of a quenched amorphous alloy ribbon containing 70 at% or more Fe or a quenched high silicon steel ribbon containing 2 to 8 wt% Si made by direct plate manufacturing from molten steel. A coating having good insulation properties, tension imparting properties, corrosion resistance and bending adhesion for electromagnetic thin strips, characterized in that a ceramic thin film with a thickness of 0.1 μm or more and 3 μm or less is applied to the electromagnetic ribbon by vacuum deposition, chemical vapor deposition or sputtering. How to form. 2. In the method described in claim 1,
The process of applying a ceramic thin film involves heating the ribbon and
Must be under at least one of the following conditions: applying a tension of 0.5Kg/mm ² or more. 3. Vacuum deposition or chemical vapor deposition on the surface of an amorphous alloy quenched ribbon containing 70at% or more of Fe or a quenched high silicon steel ribbon containing 2 to 8wt% Si made by direct plate manufacturing from molten steel. Alternatively, a ceramic thin film with a thickness of 0.1 μm or more and 3 μm or less is applied by sputtering, and after this ceramic thin film is applied, a tension-applied low thermal expansion insulation coating containing phosphate as a main component is applied. A method for forming a coating having good insulation properties, tension imparting properties, corrosion resistance, and bending adhesion properties on an electromagnetic ribbon characterized by bonding.