JPS6359241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ferrite magnetic core used in a high temperature range (for example, 150°C or higher). This is related.

Furthermore, the present invention can be used in high magnetic cores with a magnetic flux density of 500 Gauss or more, and in extremely harsh high temperature ranges (e.g. 150°C or more) that have not caused problems with conventional oxide magnetic materials. This improves power loss.

As shown in A and B in Figure 1, conventional oxide magnetic materials have a temperature at which the power loss reaches a minimum in a high magnetic field ranging from around room temperature to at most a high temperature.
In the harsh high temperature range, which exists up to 100°C and exceeds 150°C, power loss increases, making it unusable.

However, due to recent advances in peripheral technologies other than magnetic materials (e.g., transistor technology) and progress in application development, the development of oxide magnetic materials that can withstand use in high temperature ranges exceeding 150°C is a growing demand of the times. It has arisen as.

A specific example of this is ferrite, which is used as a light source for a fluorescent discharge lamp. The desired characteristics of this ferrite are shown in Figure 1C, but ferrite, which exhibits low power loss in a high temperature range of 150°C or higher, does not meet the requirements of conventional technology. However, it was difficult to concretely realize the plan.

In addition, ferrites that operate at a certain high temperature have been known as temperature-sensitive ferrites, but this is simply due to the temperature characteristics of inductance,
Alternatively, the temperature characteristics of the saturation magnetic flux density are utilized, and the characteristics shown in FIG. 1C cannot be obtained at all.

In order to eliminate the above-mentioned drawback of conventional oxide magnetic materials such as increased power loss in the high temperature range, the present invention has been developed to adjust the temperature at which the power loss is minimal according to the required application.
Manganese oxide (MnO), zinc oxide (ZnO), nickel oxide (NiO), and magnesium oxide (MgO) as a substitute for nickel oxide, lithium oxide (LiO) and By carefully selecting the basic composition of the remaining iron sesquioxide (Fe ₂ O ₃ ), we provide a technology that improves power loss in high temperature ranges.

That is, the present invention is a ferrite magnetic core that is driven at high temperatures in a magnetic field of 500 G or more, and which contains 13 to 50 mol% of manganese oxide (MnO) and zinc oxide (ZnO).
0 to 20 mol% (excluding 0), 0 to 26 mol% of at least one of nickel oxide (NiO), magnesium oxide (MgO), and lithium oxide (LiO)
(However, 0 is not included), the remainder is iron sesquioxide (Fe ₂ O ₃ )
It has a basic composition of 45 mol% or more, and
The present invention relates to a ferrite magnetic core characterized in that the Curie temperature and the temperature at which the power loss in a 700G magnetic field shows a minimum value are 250°C or higher and 150°C or higher, respectively.

In other words, the basic composition ratio of the Ni-Mn-Zn system, Mn-Mg-Zn system, or Li-Mn-Zn system is carefully selected according to the required application, and a small amount of additives are added to this to improve loss. This is an oxide magnetic material obtained by thoroughly mixing the materials, pre-calcining them at a temperature of 700°C or higher, pulverizing them, and then firing them at a temperature of 1,250°C or higher in nitrogen gas containing a small amount of oxygen. be.

Examples of the present invention will be described below.

Figure 2 shows Ni-Mn-Zn ferrite.
When iron sesquioxide (Fe ₂ O ₃ ) is kept constant at 54 mol %, the total of the other three components is 46 mol %. Namely, manganese oxide (MnO), zinc oxide (ZnO),
The relationship between nickel oxide (NiO) and the temperature at which the power loss Pc is minimal (hereinafter referred to as Tpcmin for simplicity) is shown. In FIG. 2, Tpcmin moves in the direction of arrow T.

Note that this figure 2 is for measurement conditions of 100 kilohertz and 700 gauss. All measurement conditions below are 100
This shows what was done at 700 Gauss in kilohertz.
As shown in FIG. 2, there is a clear relationship between Tpcmin and the composition, and in the present invention, this relationship was investigated in detail over the entire practical composition range. As a result, even when the amount of iron sesquioxide (Fe ₂ O ₃ ) was varied, as the amount increased or decreased,
If we reduce and increase nickel oxide (NiO), that is,
If Fe ₂ O ₃ + NiO = constant, the Kyrie point does not change, but is inversely proportional to the amount of iron sesquioxide (Fe ₂ O ₃ ).
It was discovered that although Tpcmin moves to the lower temperature side, there is no change in the tendency for other component compositions. An example of this is shown in FIGS. 3 and 4.

Figure 3 shows the relationship between other three components, namely manganese oxide (MnO), zinc oxide (ZnO), nickel oxide (NiO), and Tpcmin when 52 mol% of iron sesquioxide (Fe ₂ O ₃ ) is constant. Show relationships. Figure 4 shows
Similarly, it is a diagram when 56 mol% of iron sesquioxide (Fe ₂ O ₃ ) is constant. A comparison of Figures 2, 3, and 4 reveals that, as mentioned above, Tpcmin shifts to the lower temperature side in inverse proportion to the amount of iron sesquioxide (Fe ₂ O ₃ ), but there is no change in the tendency for other component compositions. It shows that you can't see it.

It was also found that this relationship did not change at all even if magnesium oxide (MgO) or lithium oxide (LiO) was substituted for nickel oxide (NiO).

However, in the case of magnesium oxide (MgO), when replacing the same mole as nickel oxide (NiO), Tpcmin is lower than in the case of nickel oxide (NiO).
was observed to move approximately 40°C lower in parallel.

Figure 5 shows the situation.

Furthermore, when replacing with lithium oxide, Tpcmin was observed to move in parallel to a temperature approximately 10°C higher than in the case of nickel oxide.

Figure 6 shows the situation.

However, it was also observed that the temperature characteristics of power loss showed the same tendency in both cases. Further, FIG. 7 shows an example of the temperature characteristics of power loss when the component system is changed.

When replaced with magnesium oxide (MgO),
Compared to nickel oxide (NiO), the Kyrie point is 15℃
When the temperature was lowered and replaced with lithium oxide (LiO), the Curie point increased by 5°C, and this tendency was also observed to shift in parallel over a wide range of compositions.

Therefore, the following examples will be representative of the Ni-Mn-Zn system, and the details will be explained.

As a specific example, if Tpcmin is around 240℃ (actual operating temperature range 180℃~300℃) and Tpcmin is
Consider the case of manufacturing a material that meets two types of material requirements around 290°C (actual operating temperature range of about 230°C to 350°C) and minimizes power loss Pc in the specified temperature range.

Tpcmin is 240℃ requirement is D, Tpcmin290
Let E be the requirement for °C. From the relationship in Figure 2, D is
It is obvious that E should be selected on the Tpcmin=240°C line and E should be selected on the Tpcmin=290°C line. The line of each line and the composition of iron sesquioxide (Fe ₂ O ₃ ) are determined based on considerations such as the frequency band of the required material and economic efficiency; however, the higher the frequency band, the more Select the direction with the highest nickel oxide ratio.

Tpcmin based on the required frequency band and economical conditions
Assume that both points D and E are selected on the line according to FIG.

That is, D is 54 mol% of iron sesquioxide (Fe ₂ O ₃ ), 25 mol% of manganese oxide (MnO), 10 mol% of nickel oxide (NiO), 11 mol% of zinc oxide (ZnO),
Similarly, E is 54 mol% of iron sesquioxide (Fe ₂ O ₃ ), 33 mol% of manganese oxide (MnO), 12 mol% of nickel oxide (NiO), 1 mol% of zinc oxide (ZnO),
It is.

The raw material compounds calculated and weighed to have the compositions D and E above are thoroughly mixed in a ball mill or similar mixer, calcined in air at 900°C for 3 hours, and then subjected to a ball mill or similar pulverization operation. Thoroughly pulverize by placing.

At this time, an appropriate amount of additives are added to improve loss.

100% of the sample obtained by kneading the Ni-Mn-Zn ferrites of D and E that had gone through the above steps with a binder, molding them, and firing them at 1350°C for 3 hours in nitrogen gas containing 2% oxygen. Figure 8 shows the temperature characteristics of power loss Pc at kilohertz and 700 Gauss.

Total power loss in the target temperature range as shown in Figure 8
It is clear that Pc shows a minimum value and Tpcmin shifts. As described above, the present invention shows that power loss is improved in a severe high temperature range that was unimaginable with conventional oxide magnetic materials.

Figure 9 shows manganese oxide (MnO) 23 mol%,
Electric power of samples manufactured in the same manner as in the previous example, with zinc oxide (ZnO) kept constant at 10 mol% and the ratio of iron sesquioxide (Fe ₂ O ₃ ) and nickel oxide (NiO) varied. Shows the temperature characteristics of loss Pc. In addition, the numerical value in FIG. 9 shows the mol% _{of Fe2O3} . As described above, FIG. 9 shows that as the amount of iron sesquioxide increases (the amount of nickel oxide decreases), the power loss, especially in the low temperature region, becomes better.

FIG. 9 also shows the lower limit of the iron sesquioxide (Fe ₂ O ₃ ) composition of the ferrite material for a fluorescent discharge lamp light source, which is a specific application of the present invention. In other words, in this application, the permissible limit for power loss near room temperature is approximately 1000 milliwatts/cm ³ , so iron sesquioxide (Fe ₂ O ₃ ) is required to be at least 45 mol % for this application. This shows that.

Figure 10 shows the power loss of a sample manufactured using the same method as the previous example, with iron sesquioxide (Fe ₂ O ₃ ) constant at 52 mol% and nickel oxide (NiO) at 15 mol%.
Shows the temperature characteristics of PC. Note that the numerical values in FIG. 10 indicate the mol% of zinc oxide (ZnO). As shown in Figure 10, zinc oxide decreases (manganese oxide increases)
This shows that the power loss becomes better as the temperature increases, the Curie point increases to higher temperatures, and Tpcmin also shifts to higher temperatures.

Similarly to FIG. 9, FIG. 10 also shows the upper limit of the composition of zinc oxide (ZnO) in the ferrite material for a fluorescent discharge lamp light source, which is a specific application of the present invention.
Moreover, the reason for the Curie point of the present invention is also shown at the same time.

That is, according to Figure 10, when zinc oxide is 20 mol% or more, it exceeds 1000 mw/ ^cm3 , and zinc oxide is 22 mol%.
This shows not only that the Curie point has fallen to 265 degrees Celsius, but also that power loss is rapidly deteriorating near the Curie point. From this, it is clear that the upper limit for zinc oxide is 20 mol%, and furthermore, due to the phenomenon of power loss deterioration near the Curie point, even if the material requires a Tpcmin of about 150°C, it cannot be used for practical use as a material. The reason why the Kyrie point was set at 250°C or higher is obvious, considering the safety of the temperature range.

As described above, the effects obtained by the present invention include manganese oxide (MnO) of 13 to 50 mol%;
Zinc oxide (ZnO) 0 to 20 mol% (however, 0 is not included), 0 to 26 mol% of at least one of nickel oxide (NiO), magnesium oxide (MgO), and lithium oxide (LiO) (however, 0 is not included) ), the remainder has a basic composition of 45 mol% or more of iron sesquioxide (Fe ₂ O ₃ ), and has a
A ferrite magnetic core is obtained in which the temperatures at which the power loss in a 700G magnetic field reaches its minimum value are 250°C or higher and 150°C or higher, respectively. Therefore, it goes without saying that it is now possible to realize a transformer with high output in any high temperature range; in other words, when the output is constant, the transformer itself can be made smaller.

And as a secondary effect, Ni−Mn−Zn system, Mn−
Based on detailed investigation results of wide composition range of Mg-Zn type and Li-Mn-Zn type ferrites, we are now able to manufacture temperature-sensitive ferrites for use at temperatures above 250℃, which exceeds the temperature range of conventional commercially available temperature-sensitive ferrites. It is a great invention that contributes to the electronic materials industry by making it possible.

[Brief explanation of the drawing]

Figure 1 shows the characteristics of conventional oxide magnetic materials and the power loss Pc of the ferrite magnetic core of the present invention.
This shows the temperature characteristics of Figure 2 shows the relationship between the composition of Ni-Mn-Zn ferrite and the temperature Tpcmin showing the minimum value of power loss, with iron sesquioxide (Fe ₂ O ₃ ) of the present invention kept constant at 54 mol%. This shows that. FIG. 3 shows the relationship between the composition of Ni--Mn--Zn ferrite and the temperature Tpcmin at which the power loss reaches a minimum value when iron sesquioxide (Fe ₂ O ₃ ) is kept constant at 52 mol %. Figure 4 shows Ni−Mn− when iron sesquioxide (Fe ₂ O ₃ ) is kept constant at 56 mol%.
This figure shows the relationship between the composition of Zn-based ferrite and the temperature Tpcmin that indicates the minimum value of power loss. Fifth
Figure 6 shows the case where magnesium oxide (MgO) and lithium oxide (LiO) are used as substitutes for nickel oxide (NiO) with iron sesquioxide (Fe ₂ O ₃ ) at a constant 54 mol%. The relationship between the composition of Mn-Mg-Zn ferrite and Li-Mn-Zn ferrite and the temperature Tpcmin showing the minimum value of power loss is shown. In comparison with FIG. 2, it shows that Tpcmin deviates when the composition system changes. FIG. 7 shows a typical example of the temperature characteristics of power loss when the component system is changed. Even if the ingredient system changes,
The trend of the characteristics does not change at all, indicating that Tpcmin and the Kyrie point deviate. FIG. 8 shows the temperature characteristics of power loss in the case of Ni--Mn--Zn ferrite according to the present invention, in which materials with different service temperature ranges are obtained. Figures 9 and 10 show Ni from the present invention.
-Mn-Zn ferrite shows the temperature characteristics of power loss when the composition ratio is changed.

Claims (1)

[Scope of Claims] 1. A ferrite magnetic core driven at high temperatures in a magnetic field of 500 G or more, comprising 13 to 50 mol% of manganese oxide (MnO) and 0 to 20 mol% of zinc oxide (ZnO) (with the exception of 0 ), nickel oxide (NiO), magnesium oxide (MgO),
At least one type of lithium oxide (LiO)
It has a basic composition of ~26 mol% (excluding 0), with the remainder being 45 mol% or more of iron sesquioxide (Fe ₂ O ₃ ), and the power loss at the Curie temperature and in a 700G magnetic field has reached minimum values. A ferrite magnetic core characterized by exhibiting temperatures of 250°C or higher and 150°C or higher, respectively.