JPH05299230A - Manufacturing method for low loss oxide magnetic material - Google Patents

Abstract

PURPOSE:To manufacture the oxide magnetic material at low power loss by a method wherein the temperature descending rate of said material containing V2O5, Nb2O5 in addition to the subcomponents is to be fluctuated within the range from the sustained temperature to the transfer temperature to the nitrogen 100% atmosphere. CONSTITUTION:Within the manufacturing method of low loss oxide magnetic material containing 30-42mol% of MnO, 4-19mol% of ZnO and residual mol% of Fe2O3 as the main components as well as 0.02-0.15wt.% of CaO and 0.005-0.10wt.% of SiO2 are the subcomponents furthermore, not exceeding 0.3wt% of Nb2O5 and not exceeding 0.2wt.% of V2O5 as additional subcomponents, the temperature descending rate in the sintering step is to be controlled at not exceeding 250 deg.C/hour within the temperature range from the sustained temperature to the transfer temperature to the nitrogen 100% atmosphere. Through these procedures, the temperature minimizing the power loss PB can be freely selected within the range of 20 deg.C-120 deg.C furthermore enabling the power loss PB value to be extenuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low loss oxide magnetic material used in power transformers and the like.

[0002]

2. Description of the Related Art A conventional switching power supply transformer has a switching frequency of 10 to 200K.
A low loss magnetic material corresponding to this is used as a low loss magnetic material. As a main component, 30 to 42 mol% of manganese monoxide (MnO), 4 to 19 mol% of zinc oxide (ZnO) and the balance are used. Containing ferric oxide (Fe ₂ O ₃ ) as an auxiliary component, and 0.02 to 0.15% by weight of calcium oxide (CaO) and 0.005 to 0.100% by weight of silicon dioxide (SiO ₂ ) as secondary components. An Mn-Zn based spinel ferrite containing Al has been already developed. On the other hand, when a low loss oxide magnetic material is used as a magnetic core material of a transformer for a switching power supply, it is generally designed in consideration of the temperature characteristic of the power loss P _B. That is, the temperature at which the power loss P _B becomes the minimum value must be determined in advance in consideration of the ambient temperature in which the switching power supply is used and the heat generation of the magnetic core due to the power loss.

Conventionally, the temperature at which the power loss P _{B has} a minimum value is
Manganese monoxide (MnO), zinc oxide (Z
nO) and ferric oxide (Fe ₂ O ₃ ) compounding ratios, or the valence of ions was determined by adding tetravalent titanium Ti ⁴⁺ , tin Sn ^4+, etc., but the minimum power loss There was a problem that the value of becomes large. Further, in the case of ferrite having the above-mentioned conventional composition, it is possible to change the minimum temperature of P _B without increasing the minimum value of P _B by controlling the temperature lowering rate in the sintering process, but the value itself is improved. I couldn't.

[0004]

Therefore, the technical problem of the present invention is that the temperature at which the power loss becomes the minimum value is 20 to 120.
To provide a method for producing a low loss oxide magnetic material which can be freely set within a range of 0 ° C., can further reduce power loss when the temperature is set to a particularly useful high temperature side, and has a small iron loss and a small heat generation. is there.

[0005]

According to the present invention, 30 to 42 mol% of manganese monoxide (MnO) as a main component,
It contains 4 to 19% of zinc oxide (ZnO) and the balance of ferric oxide (Fe ₂ O ₃ ), and the second component is 0.02 to 0.02.
0.15 wt% calcium oxide (CaO) and 0.00
In an oxide magnetic material containing 5 to 0.10% by weight of silicon dioxide (SiO ₂ ), 0.3
Weight% or less (not including 0) niobium pentoxide (Nb ₂ O ₅ ).
And 0.2% by weight or less (not including 0) of vanadium pentoxide (V ₂ O ₅ ) was added, and the high temperature rate in the sintering process was changed from the holding temperature to the temperature at which the atmosphere was switched to 100% nitrogen. By controlling the temperature at the minimum value of the power loss P _B in the range of 20 ° C. to 120 ° C. by controlling at 250 ° C./hour or less (not including 0) within the temperature range, the higher temperature side becomes The present invention provides a low-loss oxide magnetic material characterized in that the value of power loss P _B can be reduced.

[0006]

In the present invention, silicon dioxide (SiO 2) is used as an accessory component.
₂ ) and Mn of conventional composition containing calcium oxide (CaO)
-Zn ferrite with niobium pentoxide (N
b ₂ O ₅ ) and vanadium pentoxide (V ₂ O ₅ ) are added, and the rate of temperature decrease during sintering is controlled in the temperature range from the holding temperature to the temperature at which the atmosphere is switched to 100% nitrogen, and The ratio of trivalent to trivalent Fe ²⁺ / Fe ³⁺ and the divalent to trivalent ratio Mn ²⁺ / Mn ³⁺ of manganese ions can be controlled to arbitrarily change the minimum P _B temperature. Next to
Furthermore, by increasing the precipitation concentration of Nb ₂ O ₅ and V ₂ O _{5 to} the crystal grain boundary, the resistivity of the grain boundary is increased and the growth of the crystal grain is made uniform, so that eddy current loss on the high temperature side and It has become possible to further reduce the hysteresis loss.

[0007]

EXAMPLES Examples of the present invention will be described below.

As main components, 52.5 mol% ferric oxide (Fe ₂ O ₃ ) and 36.5 mol% manganese monoxide (M
nO) and 10 mol% zinc oxide (ZnO),
As an accessory component, 0.015% by weight of silicon dioxide (SiO 2
₂ ), 0.050 wt% calcium oxide (CaO), and 0.040 wt% niobium pentoxide (Nb ₂ O ₅ ).
Containing 050 wt% vanadium pentoxide (V ₂ O ₅ ),
These are mixed, pre-fired and granulated. The granulated powder was molded into a ring shape having an outer diameter of 30 mm, an inner diameter of 18 mm and a height of 7 mm, and was sintered at an oxygen concentration of 1 at% and a temperature of 1300 ° C. The switching temperature to 100% nitrogen was set to 1150 ° C,
Temperature decrease rate from 1300 ℃ to 1150 ℃ is 250 ℃ /
Shows the temperature and power loss values that minimize power loss when changed to hours, 150 ° C / hour, 100 ° C / hour, 50 ° C / hour, 25 ° C / hour, 15 ° C / hour, 5 ° C / hour. 1
It was shown to.

[0009]

[Table 1]

As the cooling rate becomes slower, the temperature at which the power loss becomes the minimum shifts to the high temperature side, and the value also becomes smaller. Moreover, in FIG. 1, the temperature decreasing rate is 250 ° C./hour,
The temperature characteristics of power loss at 100 ° C./hour and 15 ° C./hour are shown. From the above, it can be seen that the minimum temperature moves to the higher temperature side as the temperature lowering temperature becomes slower, and at the same time, the value also decreases. The cooling rate is 250
If it exceeds ° C / hour, the minimum value of power loss becomes large, which is not preferable. Next, Table 2 shows the values of the second component addition amount and the power loss P _B when the temperature lowering rate was 15 ° C./hour under the above-mentioned sintering conditions.

[0011]

[Table 2]

For the material in which vanadium pentoxide (V ₂ O ₅ ) and niobium pentoxide (Nb ₂ O ₅ ) are added in combination, the temperature at which the power loss P _B becomes the minimum is 100 ° C. under the main sintering conditions, and the optimum addition is made. In the amount (No4), the power loss can be reduced by about 40% compared with the conventional material (No1). Vanadium pentoxide (V ₂ O ₅ ) 0.3 wt% (No 6), niobium pentoxide (N
In the case of 0.4 wt% of b ₂ O ₅ (No. 8), different phases such as amorphous or polycrystal mainly composed of these components are generated in the crystal grains, resulting in a large power loss.

[0013] Incidentally, shows a comparison with five vanadium oxide (V ₂ O ₅₎ and five conventional example and various properties of the niobium oxide (Nb ₂ O ₅₎ The optimum addition samples (No4) (No1) Table 3 .

[0014]

[Table 3]

[0015]

As described above, silicon dioxide (SiO ₂ ) and calcium oxide (CaO) are used as auxiliary components.
Besides, vanadium pentoxide (V ₂ O ₅ ) and niobium pentoxide (N
In the range of the material containing b ₂ O ₅₎ from the holding temperature to a temperature of switching to 100% nitrogen, by changing the cooling rate, the value of the minimum value of the power loss in the range of 20 to 120 ° C. to the high temperature side A material with a small power loss P _B can be obtained at the same time as the change, and the size and weight of the transformer can be reduced.

[Brief description of drawings]

FIG. 1 is a temperature decreasing rate of 250 ° C./hour, 100 ° C./hour,
For 15 ° C. / time is a graph showing the temperature characteristics of the power loss P _B of.

[Explanation of symbols]

A When the temperature decrease rate is 250 ° C./hour in the temperature range from the holding temperature to the atmospheric temperature of 100% nitrogen. C When the temperature decrease rate in the temperature range from the holding temperature to the atmospheric temperature of 100% nitrogen is 100 ° C / hour. When the rate of temperature decrease is 15 ° C./hour in the temperature range from the F 2 holding temperature to the atmospheric temperature of 100% nitrogen.

Claims (1)

[Claims] 1. A main component of 30 to 42 mol% of manganese monoxide (MnO) and 4 to 19 mol% of zinc oxide (Zn).
O), and ferric oxide (Fe ₂ O ₃ ) as the balance, 0.02 to 0.15% by weight of calcium oxide (CaO) and 0.005 to 0.10% by weight of silicon dioxide ( SiO ₂ ), and as an auxiliary component, 0.3% by weight or less (not including 0) of niobium pentoxide (Nb ₂ O ₅ ) and 0.2% by weight or less (not including 0) of vanadium pentoxide. In the oxide magnetic material containing (V ₂ O ₅ ), 250 ° C./hour or less (0) within the temperature range from the holding temperature to the temperature at which the atmosphere is changed to 100% nitrogen in the sintering process.
By controlling at not included), the temperature at which the minimum value of the power loss P _B freely can be selected in the range of 20 ° C. to 120 ° C., characterized by an ability to yet improve the value of the power loss P _B low Method for producing lossy oxide magnetic material.