JPS6249964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the alternating current magnetic properties of an amorphous magnetic alloy ribbon in a frequency band from commercial frequencies to several tens of kilohertz or higher, and particularly to a method for reducing iron loss.

In recent years, it has become clear that amorphous alloy ribbons can be manufactured continuously by various molten metal quenching methods, including single-roll and twin-roll methods, and that they have a number of unique properties. Applications are being considered. Among these, magnetic materials are promising for use as magnetic head core materials, transformer core materials, magnetostrictive vibration core materials, and the like. In particular, regarding transformer core materials, amorphous materials have low iron loss, so in the commercial frequency range, silicon steel sheets used for pole-mounted transformer materials are used, but in high frequency bands around 20KHz, switching legs are used. If it can replace the ferrite core used in products such as Yurator, it will be of great significance in terms of energy conservation.

However, although the core loss of amorphous magnetic ribbon varies depending on the composition, it has generally been found that in the commercial frequency range, the core loss of amorphous magnetic ribbon is 1/2 to 1/2 that of current silicon steel sheets.
In the high frequency band around 20KHz, the iron loss is larger than that of the currently used ferrite, and this is the main reason preventing the practical application of amorphous magnetic ribbons as transformer materials. It is a known fact that there are.

Now, the iron loss of general metallic magnetic materials including amorphous materials is classified into so-called hysteresis loss and eddy current loss depending on the generation mechanism. Furthermore, the eddy current loss is
It is classified into classical eddy current loss, which depends on the thickness and electrical resistance of the material, and anomalous eddy current loss, which depends on the magnetic domain structure of the material.

As a result of experimentally investigating the generation mechanism of iron loss in amorphous magnetic ribbons, we found that in the high frequency region around 20KHz, eddy current loss, especially abnormal eddy current loss, accounts for 50% of the total iron loss.
We found that the proportion was as high as ~90%. We predicted that the reason why the abnormal eddy current loss is large is because there are no grain boundaries in amorphous magnetic ribbons, so the magnetic domains become large. (If the magnetic domain becomes infinitely small, the abnormal eddy current loss will be zero).

Therefore, we believe that reducing the magnetic domain size is the key to reducing iron loss in amorphous magnetic ribbons, and as a result of various experiments, we found that scratches and scratches were found on the surface and inside of the ribbons. The inventors have newly discovered that if pinholes are intentionally created, the size of the magnetic domain becomes smaller and therefore the iron loss is reduced, leading to the present invention. In the present invention, this shape defect can be easily created by making good use of the special manufacturing method of the ribbon, and is extremely superior to conventional iron loss reduction methods such as annealing in a magnetic field. It has an effect.

Example 1 The present invention will be described in detail below based on examples.

The composition is Fe ₇₈ Si ₁₀ B ₁₂ , the thickness is 25μ, and the so-called single roll method is used using the apparatus shown in Fig.
An amorphous ribbon with a width of 5 mm and a length of several tens of meters was produced.
In the figure, 1 indicates a nozzle, and 2 indicates a molten metal. The roll 3 is made of copper, and by making horizontal scratches 5 (depth is about 10 to 100μ) as shown in the figure on the outer circumferential surface where the molten metal 2 comes into contact, these scratches are transferred to the ribbon 4. Ribbon 4 had horizontal scratches.

The manufacturing conditions were a roll radius of 150 mmφ, a roll rotation speed of 3500 rpm, and a spouted molten metal temperature of 1300°C. In addition, a ribbon was produced as a comparison material using a roll without scratches and under the same production conditions as above.
Wrap both ribbons in a toroidal fashion at 450℃.
After annealing for ×30 min, iron loss was measured. The results are shown in FIG. Note that the measurement frequency is 50Hz. The effect of the present invention is clear from this figure. Kerr again
As a result of this effect, when the actual magnetic domain structure was investigated, it was confirmed that the size of the magnetic domains became smaller.

Example 2 As in Example 1, an amorphous ribbon having a composition of Fe ₇₈ Si ₁₀ B ₁₂ , having a thickness of 20 μm, a width of 5 mm, and a length of several tens of meters was produced by the so-called single roll method. However, the roll is made of copper, and the outer circumferential surface that the molten metal comes into contact with is polished with #240 sandpaper to intentionally create irregularities.

These irregularities affected the surface of the produced ribbon, and the produced ribbon had, on average, several dozen pinholes per square centimeter. The manufacturing conditions were a roll radius of 150 mmφ, a roll rotation speed of 4000 rpm, and a spouted molten metal temperature of 1300°C. A ribbon was also prepared as a comparative material under the same conditions as above, using a roll that had been polished with #1500 sandpaper and whose outer peripheral surface was mirror-finished. Wrap both ribbons separately into a toroidal
After annealing at 450°C for 30 minutes, iron loss was measured. The results are shown in FIG. Note that the measurement frequency is 20KHz. From this figure, the effects of the present invention are clear. Furthermore, when the actual magnetic domain structure was investigated using the Kerr effect, it was confirmed that buds of reversed magnetic domains occur at the pinholes, and that the size of the magnetic domains eventually becomes smaller.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing an example of the ribbon manufacturing method according to the present invention, Fig. 2 is a comparison diagram of iron loss at 50Hz between an amorphous material obtained by the present invention and a comparative material, and Fig. 3 is a comparison diagram of iron loss at 20 KHz between another amorphous material obtained by the present invention and a comparative material. 1: Nozzle, 2: Molten metal, 3: Roll, 4: Ribbon (thin strip), 5: Horizontal scratches on roll surface.

Claims (1)

[Claims] 1. A method for improving magnetic properties of an amorphous magnetic alloy ribbon, which is characterized by reducing iron loss in the ribbon by creating geometric defects on the surface and inside the ribbon. 2. In the method described in claim 1,
A method for improving magnetic properties characterized by treating geometrical defects as surface scratches. 3. In the method described in claim 1,
A method for improving magnetic properties characterized by forming a shape defect into a small hole (pinhole) that penetrates from the front surface to the back surface.