JPH03224204A - Low loss oxide magnetic material - Google Patents

Abstract

PURPOSE:To optimize the title magnetic material for switching power supply transformer while minimizing the power loss by a method wherein specific content of MnO, ZnO and remaining part of Fe2 as for the main components likewise specific content of CaO, SiO2 as for the sub components while specific content of HfO2 as for the additive are respectively used. CONSTITUTION:The title magnetic material contains 30-42mole% of MnO, 4.0-19mole% of ZnO and remaining % of Fe2O3 as for the main component likewise 0.020-0.15wt% of CaO, 0.005-0.10wt.% of SiO2 as for the sub component. Besides, as for the additives, HfO2 not exceeding 1.00wt.% or at least one kind out of ZrO2 not exceeding 0.30wt%, V2O3 not exceeding 0.20wt.%, Ta2O3 not exceeding 0.30wt.% are contained. Furthermore, as for the additives, one kind out of Al2O3 not exceeding 0.50wt.%, TiO2 not exceeding 0.30wt.% may be further contained. Through these procedures, the power loss can be minimized even at the high-frequency exceeding 100kHz.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-loss oxide magnetic material used in power transformers and the like.

[Conventional technology] In transformers for conventional switching power supplies.

A switching frequency of about 10 to 200 kHz is used, and a low-loss oxide magnetic material that is compatible with this is manganese monoxide (MnO) with a main component of 30 to 40 mol% and 5 to 15 mol. % zinc oxide (ZnO) and balance ferric oxide (Fe203)
Contains as an accessory ingredient.

0.04-0.15% by weight of calcium oxide (Cab)
and 0.010 to 0.100% by weight of silicon dioxide (S
Mn-Zn-based spinel ferrite containing z02) has already been developed.

[Problems to be Solved by the Invention] In recent years, in order to reduce the size and weight of switching power supplies, it has become common to use them at high switching frequencies of 100 k)Izz or higher.

However, when a low-loss oxide magnetic material with conventional components is used as the magnetic core material of a transformer for a switching power supply with a switching frequency of 100 kHz or higher, power loss due to iron loss is large, and the resulting heat generation causes the temperature to rise above the allowable temperature. The drawback was that the transformer itself and its surrounding parts could be damaged, making it unusable.

Therefore, one technical problem of the present invention is that the frequency is 100kHz.
Reduces iron loss even when used at higher frequencies.

Therefore, it is an object of the present invention to provide a low-loss oxide magnetic material that can be put to practical use by suppressing heat generation to below an allowable temperature.

[Means for Solving the Problems] According to the present invention, 30 to 42.0 mol% of manganese monoxide uvfno) as the main components, zinc oxide (ZnO) of 4.0 to 19 mol%, and secondary oxide as the balance. Iron (Fe2
03), 0.020 to 0.15% by weight of calcium oxide (CaO) as an accessory component, and 0.005 to 0.03% by weight of calcium oxide (CaO).
10% by weight of silicon dioxide (SiO□), and 1.00ffi% or less of hafnium oxide (H
A low-loss oxide magnetic material is obtained, which is characterized in that it contains f O□).

According to the present invention, in the low loss oxide magnetic material,
Furthermore, at least one of 0.30% by weight or less of zirconium oxide (Zr02), 0.20% by weight or less of vanadium oxide (V205), and 0.30% by weight or less of tantalum oxide (Ta205) is further included as an additive. A low-loss oxide magnetic material is obtained.

According to the present invention, as described above. In any of the low-loss oxide magnetic materials, further additives include not more than 0.50% by weight of Al2O, and not more than 0.30% by weight of TiO2.
A low-loss oxide magnetic material characterized by containing at least one of the following is obtained.

Here, in the present invention, 1.00% by weight or less of hafnium oxide (HfO2) is used as an essential additive. do.

This is because it has the effect of increasing the specific resistance of grain boundaries.

In addition, in the present invention, as an optional additive, 0.30% by weight or less of zirconium oxide (Zr02) 0.20ffif
Vanadium oxide (V2O3) below fi% and 0.300
The reason why at least one kind of tantalum oxide (Ta203) is used in an amount of % or less by weight is that the appropriate amount of these elements suppresses the growth of coarse crystal grains in the same way as hafnium oxide (HfO□) and prevents precipitation at grain boundaries. If the amount of hafnium oxide, zirconium oxide, vanadium oxide, and tantalum oxide added exceeds the above-mentioned upper limit of the appropriate amount of each component, significant grain growth will occur. This is because it is not economical and the power loss characteristics deteriorate.

Furthermore, in the present invention, in addition to the above essential additives and optional additives, additional additives include aluminum oxide (Al□03) of 0.50% by weight or less and titanium dioxide (T i 02) of 0.30% by weight or less. ) contains at least one type of aluminum oxide (A120.),
This is because, within the above upper limit, titanium dioxide (T102) dissolves in solid solution within the crystal, makes the structure within the crystal grain uniform, and increases the resistance inside the crystal.

However, exceeding this upper limit significantly increases power losses.

[Example] An example of the present invention will be described below with reference to nine drawings.

(Example 1) As the main component, 53.0 mol% of ferric oxide (Fe20
3), 37 mol% manganese monoxide (MnO) and 10
．． Contains 0 mol% zinc oxide (ZnO) and 0.025% by weight silicon dioxide (S i 02
) and 0.043% by weight of calcium oxide (CaO), hafnium oxide (HfO2) is added as an additional component, these are mixed, pre-fired, pulverized, and granulated.
After molding and pressing, the oxygen partial pressure was 0.1 at% and the temperature was 115.
Sintering was carried out at 0°C to obtain an oxide magnetic material.

Figure 1 shows the temperature T when the added amount of hafnium oxide (Hf02) is used as a parameter for the obtained oxide magnetic material.
It is a figure showing the relationship between ['C] and power loss PR [kW/11']. In Figure 1, the power loss is PB[k
/113] indicates a case where the frequency is IMHz and the maximum magnetic flux density B1 is 500G. Also.

In Figure 1, curve 1 is hafnium oxide (Hf02)
If not added, curve 2 is 0.20 weight? 6 with addition of hafnium oxide (Hf O2).

Curve 3 is 0.40 wt% hafnium oxide (Hf02)
Curve 4 is the case when 0.60% by weight of hafnium oxide (HfO2) is added.

Curve 5 is 0.80 wt% hafnium oxide (Hf02)
Curve 6 is the case when 1.00% by weight of hafnium oxide (HfO□) is added.

Curve 7 is 1.20% by weight hafnium oxide (HfO□)
The characteristics of each are shown when added. From FIG. 1, in the case of a frequency of I MHz, the power loss PB has a minimum value when the temperature is about 60° C., regardless of whether hafnium oxide (Hf02) is added or not. As the amount of hafnium oxide (HfO2) added increases, the power loss PB decreases, and the power loss PB becomes the lowest when the amount added is 0.60% by weight, and the amount added is increased beyond that. As the power loss PB increases, the power loss PB increases.

When the amount added exceeds 1.20% by weight, the power loss P3 becomes larger than when it is not added.

From the above, hafnium oxide (H
It can be seen that when 1.00% by weight or less (not including 0%) of fO2) is added, the power loss PB is smaller than when it is not added.

Table 1 shows the oxide magnetic material obtained in Example 1 (0.025% by weight of silicon dioxide (SiO
□), 0.043% by weight of calcium oxide (Cab) and 0.060% by weight of hafnium oxide (HfO2)
) and conventional oxide magnetic materials (containing 0.0% as a subcomponent).
025% by weight silicon dioxide (SiO2) and 0.043
Contains % by weight of calcium oxide (CaO) and does not add hafnium oxide (HfO7)) properties (initial permeability μi, saturation magnetic flux density B15 (magnetic flux density at magnetizing force 15 [Oe]) [G], Residual magnetic flux density B r [G]
.

It shows the holding force Hc [Oe]. The main components each contain 53.0 mol % of ferric oxide (Fe20.), 37.0 mol % of manganese dioxide (MnO), and 10.0 mol % of zinc oxide (ZnO).

As is clear from Table 1, in Example 1 of the present invention,
Characteristics required for magnetic core materials for switching power supplies 1
For example, the initial permeability μm is 1000 or more, the saturation magnetic flux density is 5
It fully satisfies the characteristics of 000G or more.

Based on the above, hafnium oxide (HfO□
) sufficiently satisfies the characteristics required as a magnetic core material for switching power supplies. 2 At a frequency of 200 kHz or higher, the power loss PB is reduced by 60% when added (for example, about 0.60% by weight) compared to when not added. Approximately 50°C
It can be seen that an improvement of 0 kW/m3 can be achieved.

Table 1 (Example 2) 53.0 mol% of ferric oxide (Fe
203), 36.0 mol% manganese monoxide (MnO
), and 11.0 mol% zinc oxide (ZnO), and calcium oxide (Cab) and silicon dioxide (SiO2) as subcomponents within the component range of conventional low-loss oxide magnetic materials (calcium oxide ( Cab) is 0.02~
0.15 weight 9.6. Silicon dioxide (S i 02 )
In addition, various additives such as zirconium oxide (Zr02), aluminum oxide (A120i), and hafnium oxide (HfO2) are added to the conventional low-loss oxide magnetic material containing zirconium oxide (Zr02), aluminum oxide (A120i), and hafnium oxide (HfO2). A plurality of low-loss oxide magnetic materials of Example 2 added in a composite manner at a ratio of
As a conventional example in which the above-mentioned additives were not added and a comparative example 2, a plurality of low-loss oxide magnetic materials to which the above-mentioned additives were added singly or in combination were fabricated.

These Example 2. In the trial production of the conventional example and comparative example 2, predetermined amounts of each oxide raw material were weighed and mixed, then granulated and molded and pressed in a nitrogen gas atmosphere at an oxygen partial pressure of 5. At less than Oat%.

A sample was obtained by firing at a temperature of 1100 to 1300°C.

Table 2 shows sample No. 15-17° No. 19.20, 22.23, 25.26 of Example 2 which was produced as a prototype, and sample layer 8.2 as a conventional example. and Samples No. 9 to No. of Comparative Example 2
.

14, No. 18, 21, and 24, the content of each subcomponent and additive component and 1 frequency 2
This figure shows the minimum value of the power loss PR with respect to the sample temperature when the maximum magnetic flux density Bm is 100 OG at 00 kHz.

According to Table 2, the additive zirconium dioxide (Z
It can be seen that the combined addition of aluminum oxide (A1203), aluminum oxide (A1203), and hafnium oxide (HfO2) reduces the power loss compared to the conventional sample N098.

This is because in these additives ZrO2 and HfO2
Al2O3 precipitates at the grain boundaries of the low-loss oxide magnetic material and increases the resistivity of the grain boundaries, and Al2O3 solidly dissolves within the crystal to increase the resistivity within the crystal and make the crystal structure uniform. It is thought that it was effective.

It is thought that these combined effects uniformize the electromagnetic characteristics within one structure and increase the resistivity of the entire structure, which reduces iron loss.

Also, in Table 2, the sample layer with 0.40% ZrO2 added +18. Sample N with A1□030.60% addition
(Sample No. 2 with L21 and HfO21,10 added
In No. 4, abnormal grain growth was observed.

This is considered to be the reason for the large power loss.

Further, in Samples Nos. 9 to 14 in Table 2, the amount of one or two additives was 0%, and it can be seen that the power loss was large and the effect was weak in this case as well.

Below Margin Table below Margin (Example 3) In addition to the conventional low-loss oxide magnetic material containing the same main components and the conventional range of subcomponents as in Example 2, titanium dioxide (
Various types of low-loss oxide magnetic materials of Example 3 were prepared in which additives of TiO2), vanadium pentoxide (V20s), and hafnium oxide (Hf02) were added in various proportions, and as comparative examples, the above-mentioned A conventional low-loss oxide magnetic material 2 to which no additives were added and a plurality of low-loss magnetic materials to which the above-mentioned additives were added singly or in combination as Comparative Example 3 were both trial-produced.

Example 3. In the trial production of the conventional example and comparative example 3, similarly to example 2, a predetermined amount of each oxide raw material was weighed and mixed, then granulated and molded and pressed in a nitrogen gas atmosphere at an oxygen partial pressure of 5. Oat% or less, 1100-130
A sample was obtained by firing at a temperature of 0°C.

Table 3 shows sample No. 3 of Example 3, 33-35°3.
7.38, 40, 41, 43.44, and sample Nα8. as a conventional example. And for samples No. 27 to 32, No. 36, and 39.42 of Comparative Example 3, the content of each subcomponent and additive component and the sample temperature of power loss when the maximum magnetic flux density Bm is 100OG at one frequency of 200kllz This shows the minimum value for .

According to Table 3, the additive titanium dioxide (TiO2
), vanadium pentoxide (V20.).

It can be seen that the combined addition of hafnium oxide (Hf 02) and hafnium oxide (Hf 02) reduces power loss compared to Sample No. 28 of the conventional comparative example. This is an additive.

■20. It is thought that HfO2 and HfO2 precipitated at the grain boundaries, increased the resistivity of the grain boundaries, and had the effect of making the crystal structure uniform, due to the combined effect of these.

It is considered that power loss was reduced in the same manner as in Example 2.

In Table 3, sample No. 39 with 0.30 wt% TiO2 added and sample 1 with 1.10 wt% HfO2 added.
In No. 42, abnormal grain growth was observed, which is considered to be the reason for the large power loss.

Samples Nos. 27 to 32 in Table 3 each contain 096 as one or two additives, and it can be seen that the power loss is large and the effect is weak in these cases as well.

Table 4 shows conventional sample No. 8 and sample \0.1 of Example 2 of the present invention, and Table 5 shows conventional sample No.
8 and sample Nα33 of Example 3, the respective initial magnetic permeability μ and saturation magnetic flux density B15. The electromagnetic characteristics of residual magnetic flux density Br and resistivity ρ are compared.

In Tables 4 and 5, for μ, B+s, and Br,
Sample No. 8 and kl 5. Alternatively, both samples 111O and 33 are comparable, and only the resistivity is the same as No. 15 of Example 2.
Or N in Example 3 (each of L33 is the conventional Nα8
The value is more than 10 times that of the previous year. It is understood that this marked improvement in resistivity is the main reason for the reduction in eddy current loss.

Table below Margin 1 Example 2.3 of the present invention provides a low-loss oxide magnetic material that reduces power loss at frequencies of 100 kHz or higher and is excellent as a transformer core material for switching power supplies at high frequencies of 100 kHz or higher. It was confirmed that this was obtained.

Margin below (Example 4) As the main component, 50.0 mol% of ferric oxide (Fe20
．． ), 39.0 mol% manganese monoxide (M n O)
and 8°0 mol% of zinc oxide (ZnO), silicon dioxide (S l 02 ) and calcium oxide (
CaO), hafnium oxide (Hf02), zirconium oxide (ZrO2).

Aluminum trioxide (A1203) and vanadium pentoxide (V 20 q-) are added singly or in combination and mixed,
After granulation and molding press, the oxygen partial pressure was reduced to 5. Oat% or less, each composition was sintered at the optimum sintering temperature of 1100 to 1300''C.

Table 6 shows that the main component is 53.0 mol% ferric oxide (
F j203 ), 39.0 mol% manganese monoxide (
High permeability Mn-Zn ferrite containing 8.0 mol% zinc oxide (ZnO) and silicon dioxide (S i O2) as one minor component.

Calcium oxide (CaO) is added, and furthermore, hafnium oxide (Hf02) and zirconium oxide (Zr02) are added.
), and as a selective component aluminum oxide (A1
203) and vanadium pentoxide (V20,) are added in combination, one frequency is IMHz.

The values of power loss (iron loss) for each composition at around 60°C when the value of maximum magnetic flux density B is 500G (Gauss) are shown.

This will be explained with reference to Table 6 showing the composition and power loss (iron loss) values of the present invention.

Table 6 shows the relationship between the amount of each subcomponent added and power loss (iron loss).

From Table 6, hafnium dioxide (HfOz), zirconium dioxide (Z "0□), aluminum oxide (A 120
3') Due to the combined addition of vanadium pentoxide (V2O5), the power loss value shows a lower value compared to that of conventional low-loss oxide magnetic materials.

It can be seen that the characteristic values are improved by approximately 30% compared to the conventional values.

Addition of 1.10% by weight of hafnium oxide (Hf02) (sample number 52), 0.40% of zirconium dioxide (ZrO□)
wt% addition (sample number 60), aluminum oxide (A
I203) 0.60% by weight added (sample number 63),
When 0.25% by weight of vanadium pentoxide (V2O) was added (sample number 66), abnormal grain growth was observed in the crystal grains, the specific resistance ρ was also deteriorated, and the power loss was large.

(Example 5) As the main component in the same manner as in Example 4.

50.0 mol% ferric oxide (Fe2o3).

39.0 mol% manganese monoxide (MnO) and 8.0
Mol% of zinc oxide (ZnO), silicon dioxide (SiO□), calcium oxide (Cab), hafnium oxide (HfO2), zirconium oxide (Zr02) as subcomponents.
), and aluminum oxide (A I 2
03), titanium dioxide (T i 02 ) is added singly or in combination, mixed, granulated, and pressed, and then heated to an oxygen partial pressure of 5.0 in a nitrogen gas atmosphere. Qat% or less,
Each composition was sintered at the optimum sintering temperature of 1100 to 1300°C.

Table 7 shows 53.0 mol% of ferric oxide (F) as the main component.
e204) 39.0 mol% manganese monoxide (M n
O) and silicon dioxide (Sin2) as a subcomponent.
), calcium oxide (CaO), and furthermore hafnium oxide (Hf02) and zirconium oxide (ZrO2).
2), and aluminum oxide (Al□0
．． ) and titanium dioxide (T i 02 ) are added in combination, the two frequencies are I MHz and the operating magnetic flux density B is 5.
Power loss (iron loss) at 60°C in the case of 00G (Gauss)
The values for each composition in the vicinity are shown.

Table 7 showing the composition of the present invention and the values of power loss (iron loss) will be explained. Table 7 shows the relationship between the amount of each subcomponent added and power loss. From Table 7, hafnium oxide (Hf
O□), zirconium dioxide (Z r 021. Aluminum oxide (A120B).

By complex addition of titanium dioxide (TiO2).

It can be seen that power loss has improved. In addition, as two examples of power loss, as mentioned above, the measured values are shown at a frequency of IM)Iz and a maximum magnetic flux density of 500G (Gauss), but at 100K.
All similar power losses are seen at frequencies above Hz.

Addition of 1.10% by weight of hafnium oxide (HfO□) (sample number 82), 0.40% of zirconium oxide (Zr02)
Weight% addition (sample number 85) Aluminum oxide (Al□
03) Addition of 0.60% by weight (sample number 88), addition of 0.35% by weight of titanium dioxide (T i O□) (sample number 9)
Regarding 1).

Growth of abnormal grains was observed in the crystal grains, the specific resistance ρ was also deteriorated, and the power loss was increased.

Table 8 shows sample number 83 in Example 5.

For the conventional composition (sample number 47.71), the initial permeability μ
, saturation magnetic flux density B19. Residual magnetic flux density Br.

A comparison of specific resistance ρ is shown.

Table 8 shows sample number 58 in Example 4.

Initial permeability μ for conventional composition (sample number 69).

The values of saturation magnetic flux density B15 + residual magnetic flux density Br, coercive force He, and specific resistance ρ at a magnetizing force of 150e are shown.

This value is more than 20 times higher than that of low-loss magnetic materials with conventional compositions.

Further, in Table 8, when comparing various characteristics of sample number 80 of Example 5 according to the present invention and the conventional sample (sample number 69), it is found that the specific resistance ρ is about 20 times or more.

In addition, Example 4. In Example 5, the sintering temperature at an oxygen partial pressure of 0.5% in a nitrogen gas atmosphere is:

Sintering was carried out at an optimum temperature in the range of 1100-1300°C.

Below Margin Table 7 Table 7 (Example 6) 53.0 mol% of ferric oxide (Fe, Os
), 39.0 mol% manganese monoxide (MnO), and 8.0 mol% zinc oxide (ZnO), and contains 0.010 to 0.040 wt% silicon dioxide (
SiO2).

0.020-0.15% by weight of calcium oxide (Cab
, ), and 0.01 to 0.80% by weight of hafnium oxide (Hf02) as an additive component 0.005 to 0.30
After adding 0% by weight of tantalum oxide (Ta205) and mixing them in a ball mill, pre-baking, pulverizing, granulating, and forming press, the oxygen partial pressure is 0 to 3% (excluding 0). ).

Sinter at a temperature of 1100-1300°C for 1-4 hours.

An oxide magnetic material was obtained.

Table 9 shows the samples that showed the best core loss characteristics among the oxide magnetic materials obtained by changing the sintering conditions in each composition. , HfO2
), the power loss PB (mW/cc) is shown when the temperature is 60° C. and the Kinto density is 500 G when tantalum oxide (Ta205) is used as a parameter.

In Table 9, sample number 106 has a main component of 53.
0 mole % ferric oxide (Fe20.).

39.0 mol% manganese monoxide (MnO), μ and 8.
0 mole? Contains 6 zinc oxide (ZnO).

0.030% by weight silicon dioxide (Sin2).

0.080 weight ji 96 calcium oxide (Cab) (
Conventional M for power supplies that does not contain hafnium oxide (HfO□) or tantalum oxide (Ta20q) as subcomponents.
n-Z n-based ferrite.

It can be seen that the oxide magnetic material of the present invention is superior to the conventional material (sample 106) in all cases. In addition, silicon dioxide (5102) is 0.030% by weight, calcium oxide (CaO) is 0.060% by weight, hafnium oxide (HfO2) is 0.15% by weight, and tantalum oxide (TazO) is 0.05% by weight. Sample No. 102, which was prepared by adding % by weight, has a power loss PB that is approximately 1/2 that of conventional ferrite, realizing extremely low loss characteristics.

Table 9 [Effects of the Invention] As explained above, according to the present invention, in the Z n-Mn ferrite oxide magnetic material containing silicon dioxide and calcium oxide, 1.00% by weight or less of HfO2 as an additive. Fully satisfies various characteristics required for a transformer for switching power supplies, and has a single frequency of 100kHz.
Even at high frequencies above z, power loss can be reduced compared to conventional products.

Small size switching power supply as a material for high frequency magnetic core.

It is possible to provide a material that is fully compatible with weight reduction.

According to one aspect of the present invention, in this Zn-Mn ferrite-based oxide magnetic material, as an additive.

Furthermore, 0.30% by weight or less of zirconium oxide (Z
r02 ), 0.30% by weight or less tantalum oxide (Ta
2o3), various characteristics required for a transformer for a switching power supply can be further improved.

Furthermore, according to one aspect of the present invention, these Zn-Mn ferritic oxide magnetic materials further include at least one of A 1203 of 0.50% by weight or less and TiO2 of 0.30% by weight or less.

Various characteristics such as power loss can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between temperature and power loss (Ps) of a low-loss oxide magnetic material according to an example of the present invention. As a comparative example, a material without hafnium oxide (HfO2) added (
Curve 1) and 1,20% by weight hafnium oxide (HfO
2) is also shown (curve 7).

Claims (3)

[Claims] 1. The main components are 30-42.0 mol% manganese monoxide (MnO), 4.0-19 mol% zinc oxide (ZnO).
), and the remainder contains ferric oxide (Fe_2O_3), with 0.020-0.15% by weight of calcium oxide (CaO) and 0.005-0.10% by weight of silicon dioxide (SiO_2) as accessory components. and 1 as an additive.
．． A low-loss oxide magnetic material characterized by containing 00% by weight or less of hafnium oxide (HfO_2). 2. In the low-loss oxide magnetic material according to the first claim, further additives include not more than 0.30% by weight of zirconium oxide (ZrO_2), not more than 0.20% by weight of vanadium oxide (V_2O_5), and 0.30% by weight or less. % or less of at least one kind of tantalum oxide (Ta_2O_5). 3. In the low-loss oxide magnetic material according to the first or second claim, 0.50% by weight or less of A is further added as an additive.
A low-loss oxide magnetic material comprising at least one of l_2O_3 and 0.30% by weight or less of TiO_2.