JPH0457628B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a low-loss oxide magnetic material, and in particular contains manganese monoxide (MnO) in an amount of 30 to 37 mol%, zinc oxide (ZnO) in an amount of 10 to 15 mol%, and the balance being zinc oxide. Contains diiron (Fe ₂ O ₃ ), with 0.02-0.10% by weight of calcium oxide (CaO) as a secondary component
and 0.005 to 0.100% by weight of silicon dioxide (SiO ₂ ). [Prior art] Manganese-zinc ferrite is used in various communication devices,
It is widely used as a transformer material in consumer equipment, etc., but in conventional transformers for switching power supplies, the switching frequency is only 10 to 100k.
Hz, and materials with the above-mentioned components have already been developed as low-loss oxide magnetic materials to accommodate this. [Problem to be solved by the invention] In recent years, there has been a trend to use switching power supplies at high frequencies of 100 kHz or higher in order to make them smaller and lighter, and there is a need for transformer materials that meet this purpose. ing. However, when a low-loss oxide magnetic material having conventional components is used as a magnetic core material for a transformer for a switching power supply with a switching frequency of 100 kHz or more, it has the drawback of high core loss and heat generation. Therefore, the technical problem of the present invention is that the frequency is 100k.
An object of the present invention is to provide a low-loss oxide magnetic material that can reduce iron loss even when used at high frequencies of Hz or higher. [Means for solving the problem] According to the present invention, as a main component, 30 to 37 mol%
Contains manganese monoxide (MnO), 10-15 mol% zinc oxide (ZnO) and the balance ferric oxide (Fe ₂ O ₃ ), and 0.02-0.10 wt% calcium oxide (CaO) as a subcomponent. , 0.005-0.100 wt% silicon dioxide ( _SiO2 ), 0.121 wt% or less zirconium dioxide ( _ZrO2 ), and 0.060 wt% or less aluminum trioxide ( _{Al2O3 )} . ) can be obtained.A low-loss oxide magnetic material is obtained. [Examples] Examples of the present invention will be described below with reference to the drawings. <Example 1> Figure 1 shows that the main components are 52.0 mol% ferric oxide, 34.5 mol% manganese monoxide (MnO), and 13.5 mol% ferric oxide.
Contains mol% of zinc oxide (ZnO), and mixes silicon dioxide (SiO ₂ ), calcium oxide (CaO), zirconium dioxide (ZrO ₂ ), and aluminum trioxide (Al ₂ O ₃ ) as accessory components, FIG. 2 is a diagram showing the minimum value of the power loss P _B [kW/m ³ ] of the oxide magnetic material obtained by sintering at a temperature of 1310° C. with an oxygen partial pressure of 1.3 at% after granulation and mold pressing. . However, silicon dioxide (SiO ₂ ), calcium oxide (CaO), zirconium dioxide (ZrO ₂ ), and aluminum trioxide (Al ₂ O ₃ ) were added in the ratio shown in Figure 1, with a total amount of 0.151% by weight. define the amount;
Furthermore, the ratio of the amounts of silicon dioxide (SiO ₂ ) and calcium oxide (CaO) added was 1:2.4. Note that FIG. 1 shows the minimum value of power loss when the frequency is 100kHz and the maximum magnetic flux density B _n is 2000G. <Example 2> Fe ₂ O ₃ (52.0 mol%), MnO (34.5 mol%), ZnO
(13.5 mol%) as the main component, and ZrO ₂ as a subcomponent.
Keeping the amount constant at 0.076wt%, other subcomponents are added as shown in Table 1, and the minimum power loss in this case is shown in Table 1. The relationship is shown in Figure 2. Power loss is at frequency 100kHz, maximum magnetic flux density B _n
These are the measurement results under 2000G conditions. From the results in Table 1 and Figure 2, it is clear that Al ₂ O ₃ is 0 to 0.
It can be seen that the power loss is improved by adding 0.06wt% (not including 0).

[Table] <Example 3> Fe ₂ O ₃ (52.0 mol%), MnO (34.5 mol%), ZnO
Table 2 shows the minimum power loss when Al ₂ O 3 (13.5 mol%) is the main component, and other subcomponents are added as shown in Table 2, with a constant Al 2 O ₃ 0.030 wt%. Figure 3 shows the relationship between temperature T [°C] and power loss. The measurement conditions are the same as in Example 2. From the results shown in Table 2 and FIG. 3, it can be seen that the addition of ZrO ₂ improves power loss.

[Table] <Example 4> Fe ₂ O ₃ (52.0 mol%), MnO (34.5 mol%), ZnO
(13.5 mol%) as the main component, SiO ₂ 0.013wt%,
With CaO0.032wt% constant, other subcomponents are listed.
Table 3 shows the minimum value of power loss when added in the amount shown in Table 3, and the relationship between temperature T [° C.] and power loss is shown in FIG. The measurement conditions are the same as in Example 1. From the results shown in Table 3 and FIG. 4, it can be seen that power loss is improved by adding ZrO ₂ and Al ₂ O ₃ in combination. From Figures 2 to 4, when the frequency is 100kHz,
The power loss has a minimum value when the temperature is about 70-90℃, regardless of whether ZrO ₂ and Al ₂ O ₃ are added, but it is better when ZrO ₂ and Al ₂ O ₃ are added. , are smaller than those without them, especially at a temperature of about 100°C, which is about 35% smaller. From the above, the power loss is SiO ₂ 0.013wt%,
CaO 0.032wt%, ZrO ₂ 0.076wt%, Al ₂ O ₃ 0.030wt
It can be seen that the minimum value is reached when the value is %. Therefore, at frequencies above 100kHz, ZrO ₂ 0.121wt
It can be seen that the power loss is smaller when Al ₂ O ₃ is added in amounts of 0.060 wt % or less than in the case where they are not added. Table 4 shows oxide magnetic material No. 1 obtained by the present invention (SiO ₂ 0.013wt% as a subcomponent,
CaO 0.032wt%, ZrO ₂ 0.076wt%, Al ₂ O ₃ 0.030wt
%) and conventional oxide magnetic material No. 2 (as a subcomponent)
_{Characteristics} ( _initial permeability _{μ i saturation magnetic} flux density
B ₁₅ [G] Residual magnetic flux density Br [G], specific resistance ρ [Ω・
cm〕). The main components are Fe ₂ O ₃ (52.0 mol%),
Contains MnO (34.5 mol%) and ZnO (13.5 mol%). As is clear from Table 4, No. 1 of the present invention has various properties required for a magnetic core material for a switching power supply, such as an initial permeability μ _i of 2000 or more, and a saturation magnetic flux density.
B ₁₅ satisfies the characteristics of over 5000G. Furthermore, regarding the specific resistance ρ, No. 1 of the present invention is about 8 times better than the conventional No. 2. This is due to the additive ZrO ₂ precipitating at the grain boundaries, which improves the specific resistance ρ, improves overcurrent loss, and reduces power loss.

【table】

〔Effect of the invention〕

As can be seen from the above description, according to the present invention, the additives ZrO ₂ and Al ₂ O ₃ fully satisfy the various characteristics required as a magnetic core material for a switching power supply, and even at a frequency of 100kHz or higher.
Compared to the power loss without adding them,
It can be seen that this can be significantly reduced.

[Brief explanation of the drawing]

Figure 1 shows the power loss (P _B ) when the frequency is 100 kHz and the maximum magnetic flux density B _n is 2000 G at each mixing ratio of the subcomponents added to the main component according to the first embodiment of the present invention. FIG. 2 is a correlation diagram between temperature T (°C) and power loss (P _B ) in the oxide magnetic material according to the second embodiment of the present invention,
Fig. 3 is a correlation diagram between temperature T (°C) and power loss (P _B ) in the oxide magnetic material according to the third embodiment of the present invention, and Fig. 4 is a diagram showing the correlation between the temperature T (°C) and power loss (P B ) according to the fourth embodiment of the present invention. FIG. 2 is a correlation diagram between temperature T (° C.) and power loss (P _B ) in an oxide magnetic material.

Claims (1)

[Claims] 1 Contains 30 to 37 mol% manganese monoxide (MnO), 10 to 15 mol% zinc oxide (ZnO), and the balance ferric oxide (Fe ₂ O ₃ ) as a main component, and 0.02 mol% as a subcomponent. In a low-loss oxide magnetic material containing ~0.10 wt% calcium oxide (CaO) and 0.005-0.100 wt% silicon dioxide ( _SiO2 ),
A low-carbon material characterized by adding 0.121% by weight or less (excluding 0%) of zirconium dioxide (ZrO ₂ ) and 0.060% by weight or less (not including 0%) of aluminum trioxide (Al ₂ O ₃ ). Loss oxide magnetic material.