JPH0710744B2 - Low loss oxide magnetic material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a low-loss oxide magnetic material made of Mn—Zn ferrite suitable for use in a magnetic core for a power supply such as a display monitor.

[Conventional technology]

Conventionally, as this kind of power supply ferrite, there is Mn-Zn type ferrite proposed by the applicant in Japanese Patent Publication No. 53-28634.
This Mn-Zn system ferrite has CaO, SiO ₂ , Cl and SnF ₂ added to reduce power loss.

[Problems to be Solved by the Invention]

By the way, in recent years, due to demands for higher resolution of display monitors and the like and larger screens of color televisions for consumer use, power supplies used for these have been increasing in operating frequency and load.

However, the conventional Mn-Zn ferrite has a problem that power loss increases, the temperature of the power supply rises remarkably, and the reliability decreases greatly.

In order to solve the above problems, it is an object of the present invention to provide a low-loss oxide magnetic material composed of a low-loss Mn-Zn ferrite, which has significantly improved power loss even at high frequencies and high loads. .

[Means for Solving the Problems]

The low-loss oxide magnetic material of the present invention is mainly composed of Fe ₂ O ₃ 52 to 56 mol%, MnO 32 to 42 mol% and ZnO 5 to 15 mol%, to which P is added at 10 to 70 ppm and SiO ₂ is added. 100-300ppm, CaO
The above-mentioned problems of the prior art are solved by simultaneously containing 200 to 2000 ppm as a subcomponent.

[Action]

The low-loss oxide magnetic material of the present invention is composed of Mn-Zn based ferrite and contains Fe ₂ O ₃ , MnO and ZnO as main components, P as an auxiliary component of 10 to 70 ppm, SiO ₂ of 100 to 300 ppm,
CaO is a composite addition of CaO at a weight ratio of 200 to 2000 ppm, and is obtained by blending each component in the state of an oxide or in the form of a salt to be an oxide and firing.

The low-loss oxide magnetic material of the present invention can remarkably reduce the power loss, and can realize a sufficiently low-loss characteristic even in the frequency region of about 130 kHz. When used as a transformer core,
Although it generates heat during operation, the low-loss ferrite of the present invention
The power loss can be set to be lowest in the temperature range of 60 ℃ to 100 ℃. Therefore, power loss during actual operation can be reduced.

Example of Invention

 Examples of the present invention will be described below.

Fe ₂ O ₃ 53.5 mol%, MnO 38.5 mol% and ZnO 8.0 mol% were calcined and then finely pulverized to obtain a ferrite powder, and H ₃ PO ₄ 79 ppm (P As 30pp
m), SiO ₂ 200ppm, CaCO ₃ 1640ppm (CaO 1000pp
m) was added and mixed, a polyvinyl alcohol solution was added as a binder, and the mixture was granulated and molded into a ring-shaped sample having an outer diameter of 60 mm, an inner diameter of 40 mm and a height of 10 mm at a molding pressure of 1 ton / cm ² . However, as for these additives, those contained in the raw material were analyzed in advance, and the addition amounts were adjusted so as to be the above values as a whole. This sample was subjected to 1350 in an N ₂ atmosphere with controlled oxygen concentration.
Main firing was performed at 2 ° C. for 2 hours.

The power loss of this sample was measured at a frequency of 25 kHz, a magnetic flux density of 2000 Gauss and a temperature of 100 ° C., and the result was 60 mW / cm ³ . The waveform at this time is a sine wave. Also, 10kHz, 1
As a result of measuring the initial magnetic permeability μi at 0 T and 10 mA, it was 1883.

Further, Table 1 shows the results of measuring the power loss and μi with the same main component and the same sample preparation method with different subcomponents.

The conditions for measuring the power loss and μi in Table 1 are as in Example 1.
Is the same as.

From the above results, it is apparent that the combined addition of P, SiO ₂ and CaO significantly improves the power loss and obtains a low loss oxide magnetic material.

However, if P as an accessory component is less than 10 ppm, the crystal grain size will be small, and if it is more than 70 ppm, it will be large.
It is inappropriate because the power loss increases together.

When the content of SiO _{2 as a} sub-component is less than 100 ppm or more than 300 ppm, the electrical resistance decreases and the power loss increases, which is unsuitable. When CaO is more than 2000 ppm, the crystal grain size becomes small, but the hysteresis loss increases and the power loss increases. When CaO is less than 200 ppm, the grain boundary layer becomes thin and eddy current loss increases, which is not suitable. Further, if the above-mentioned subcomponents in the present invention are contained before the main calcination, the addition may be carried out in any step.

〔The invention's effect〕

As described above, according to the present invention, Fe ₂ O ₃ , MnO and Zn
O is the main component, P is 10 to 70 ppm and SiO ₂ is 10 as secondary components.
By adding 0 to 300 ppm and CaO to 200 to 2000 ppm in combination, power loss can be significantly reduced, which can contribute to higher efficiency and miniaturization of power supplies for high frequency display monitors, large screen color TVs, etc. It is extremely beneficial.

Claims (1)

[Claims] 1. Fe ₂ O ₃ 52 to 56 mol%, MnO 32 to 42 mol% and ZnO 5 to 15 mol% as main components, and P to 10 to 70 p.
A low loss oxide magnetic material characterized by containing pm, SiO ₂ of 100 to 300 ppm and CaO of 200 to 2000 ppm as auxiliary components at the same time.