JP3747234B2 - Method for producing soft ferrite - Google Patents

Description

【００４５】
【発明の効果】
本発明によれば、硼素と燐の含有量及びコンタミ量を含めて各々０．００２０wt% ，０．００２０wt% 以下，和として０．００４wt% 以下（零を含まず）に押え、Ｆｅ2 Ｏ3 ，ＭｎＯ，及びＺｎＯを主成分とし副成分としてＳｉＯ2 換算で０．００５〜０．０２５wt% のＳｉ，ＣａＯ換算で０．０２〜０．１５wt% のＣａを含み、添加物としてＮｂ2 Ｏ5 換算で０．０５wt% 以下の ，Ｖ2 Ｏ5 換算で０．０５wt% 以下のＶ，ＳｎＯ2 換算で０．４wt% 以下のＳｎ及びＴｉＯ2 換算で０．３wt% 以下のＴｉの１種以上を添加することによって小型軽量な高周波電源を実現できる。
【図面の簡単な説明】
【図１】フェライト中の燐及び硼素含有量によるコアの損失の変化を示すグラフである。
【図２】燐含有量及び焼成温度によるコア損失の変化を示すグラフである。
【図３】燐含有量及び焼成昇温部の酸素分圧によるコア損失の変化を示すグラフである。[0001]
[Industrial application fields]
In recent years, with the widespread use of electronic devices, there has been an increasing demand for smaller and lighter devices. In particular, the miniaturization of the power source, which occupies the main part in terms of both weight and volume, is the target. It is increasing. Since the ferrite magnetic material used in this application is operated in a high frequency and strong magnetic field, the power loss is significantly larger than that of a general application.
[0002]
The present invention relates to a method of manufacturing a soft ferrite for a high frequency power source that can reduce the high frequency power loss and can be miniaturized.
[0003]
[Prior art]
Conventionally, in the production of this kind of high magnetic permeability and low loss magnetic material, it is vaguely necessary to use a material with extremely low impurities contained in the starting material. In particular, in the case of improving the characteristics by adding a trace amount of added component, it has become a situation that a raw material having a sufficiently low impurity as compared with the trace amount of added component must be selected. However, if the required characteristics are improved only by selecting raw materials with high purity, the cost is naturally increased, and in some cases, the practicality of the product is lost.
[0004]
As countermeasures, for example, CaO and SiO2 are typical impurities for manganese zinc-based ferrites, and at the same time, they are effective and often used as additives for reducing loss as will be described later. It is known. It is also known that the addition / containment of a substantial amount of phosphorus or mixing in the process has a vague effect on the properties of ferrite due to “only the cause of the composition component”.
[0005]
For example, Japanese Patent Laid-Open No. 2-30660 discloses that the crystal grain size is small when the amount of phosphorus as a minor component is less than 0.001 wt%, and increases when the amount is more than 0.007 wt%. Therefore, it is described as being inappropriate, and the claims also clearly state that “phosphorus is 0.001 to 0.007 wt%”. That is, the range of phosphorus content is specified as an essential requirement for a low-loss oxide magnetic material. It is noted that the amount of the additive containing phosphorus, etc. is preliminarily analyzed and considered in the raw material.
[0006]
According to Japanese Patent Laid-Open No. 4-92822, the amount of phosphorus added is 0.008 wt% to 0.015 wt%, which has the effect of lowering the final sintering temperature by 20 ° C. Although it has contributed to the improvement of the life and thermal energy of the steel, it is described that the loss could be reduced by “limiting the amount of phosphorus added”. In the examples, it is explained that the core loss can be reduced by adding 0.0033 wt% phosphorus. Further, in the example for confirming the relationship between the phosphorus content and the loss, the level of the amount of phosphorus added is 0.0012 to 0.01 wt% (the graph showing the effect is shown in FIG. 1). The loss measurement is performed at 16KHz.
[0007]
Therefore, the idea of these prior arts is to contain a considerable amount of phosphorus (0.0012 wt% or more) in order to lower the sintering temperature. However, if the amount is kept below 0.005 wt%, the core loss can be kept low. In the claims of the above-mentioned JP-A-2-30660 published before the filing of the present application, the amount of phosphorus is limited to 0.001 to 0.007 wt% and is based on the same logic. It is understood that the effect of interaction between the addition amount or the small amount of phosphorus of 0.002 wt% or less and the firing conditions is not recognized. The lack of any examination or explanation of boron / phosphorus in the raw material suggests that “a considerable amount can be included”.
[0008]
Japanese Patent Laid-Open No. 5-217733 discloses that the core loss at (25 KHz-200 mt-100 ° C.) is 55 KW / m 3 or less, including that containing phosphorus in the raw material, 0.001 wt% or less. It is necessary to make it. However, if manufacturing conditions other than components and subcomponents (when the sintering temperature is too low) are inappropriate, even if phosphorus is 0.001 wt% or less, phosphorus may be worse than 0.001 wt% or more. Some have been suggested and acknowledged the lack of reproducibility.
[0009]
Further, in JP-A-6-140231, it is desirable that the phosphorus content in the soft ferrite is controlled to 0.003 wt% or less, that is, 0 to 0.003 wt%. In Example 1, the phosphorus content in the sample No. 1 is controlled. It is described that the total was less than 0.003 wt%, and Samples Nos. 2 to 49 were the same. In this prior art, only phosphorus and its presence are not related to the amount, but only vaguely suggest that sintered ferrite is affected. Accordingly, it is understood that phosphorus does not interact with subcomponents in the range of 0 to 0.003 wt%.
[0010]
In order to compare and grasp the prior art as a problem to be solved by the invention, the measurement frequency of the low loss material is extremely important, and the same material may sometimes show the opposite loss value around 20KHz and around 100KHz. is there. That is, even with the same component composition, the electrical characteristics differ depending on the crystal growth state, the grain boundary, and the degree of oxidation within the crystal.
[0011]
The main component expected to improve the properties and costs of manganese-zinc ferrites, such as preventing impurities from being mixed, making the composition uniform, and making the particles finer and sintered.・ Many of the solution mixing / spray roasting methods of subcomponents are disclosed. For example, in JP-A-3-116803, when known additives Si, Ca, and Hf of conventional oxide mixing methods are sprayed, Hf dissolves not only in grain boundaries but also in ferrite, so that it has a higher resistance. It is said that power loss is reduced due to particles.
[0012]
In Japanese Patent Laid-Open No. 4-12504, if the Si and Ca subcomponents are dissolved and added simultaneously before spray roasting of Mn—Zn ferrite, the entire process is simplified and the characteristics are slightly improved.
[0013]
In Japanese Patent Laid-Open No. 4-192310, when adding 0.05 wt% or less of Bi to Mn—Zn ferrite to obtain a High μ material, the composition is uniform by dissolving and mixing the Bi or Bi salt compound and spray roasting. In addition, the crystal grains are uniform, the grain size is increased, and the number of pores is reduced, so that the μi characteristic is greatly improved.
[0014]
Furthermore, Japanese Patent Laid-Open No. 4-307903 states that the loss characteristics can be greatly improved by adding Si, Ca, Zr to soft ferrite by spray roasting. However, in any of the prior art, if the additive component is spray roasted simultaneously with the main component, it becomes fine particles with a uniform composition and a uniform structure, but the effect of the additive is the same tendency and the wrinkle improvement compared with the conventional method There are few results that are not expected at all because the sintering conditions are slightly shifted.
[0015]
In JP-A-3-163802, phosphorus oxide / boron oxide is 0.01 wt% or less (preferably 0.00005 wt% or more), and in JP-A-3-223119, phosphorus oxide / boron oxide is 0.003 wt% or less (preferably Is 0.0001 wt% or more), but all are clearly described as useful components that can reduce iron loss by adding a small amount. Iron loss tends to decrease with increasing amount of additive Is not only seen, but compared to the upper limit Preferred amount of phosphorus added , 0.00005 wt% and 0.0001 wt% are values that can be expressed as being hardly included even in the light of detection accuracy, and it is judged that the amount of phosphorus directly affects the reduction of iron loss. This prior art suggests that there are other essential main factors, and the present application has found this essential requirement.
[0016]
Summarizing the prior art described above, in order to reduce the core loss of Mn—Zn ferrite, the phosphorus content is appropriately set in JP-A-2-3060, JP-A-4-92822, and JP-A-5-217733. In addition, it has been proposed to add a small amount of boron alone or in combination in Japanese Patent Application Laid-Open No. 3-163802 and Japanese Patent Application Laid-Open No. 3-223119. In order to reliably reduce the loss of the ferrite core with good reproducibility, it is not necessary to control the phosphorus / boron content, but the amount of each of phosphorus and boron mixed in the ferrite and raw materials and in the manufacturing process. And the total amount is controlled to a specific amount below a certain amount, and it has been found that it is essential to adjust the firing conditions including the control of the oxygen amount from the time of temperature rise. In JP-A-3-116803, JP-A-4-12504, and JP-A-4-192310, attempts have been made to mix solutions of main components, subcomponents, additives, spray roasting, etc. The product and impurity control effects show the same tendency, and the improvement effect is only emphasized or the manufacturing conditions are slightly shifted.
[0017]
[Problems to be solved by the invention]
In general, it is more advantageous to increase the processing frequency as described above in order to reduce the size and weight of the power supply device. However, in reality, it is considered that the range of about 500 KHz can be realized due to various restrictions. Conventionally, as this type of ferrite, those mainly composed of manganese, zinc, iron oxide and the like are considered suitable. In addition, we have been responding to this demand by studying and improving subcomponents, additives, manufacturing conditions, etc., but since they operate in a relatively strong magnetic field unlike the loss of weak magnetic fields, The biggest problem lies in the fact that the magnetic loss is significantly increased at a high frequency as compared with the application, and an approach tailored to this viewpoint becomes necessary.
[0018]
Therefore, even if the main component is a conventionally known manganese zinc system, the saturation magnetic flux density Bs related to hysteresis loss and ΔB which is the difference between Bs and the residual magnetic flux density Br are large, and the specific resistance related to eddy current loss. Need to be big. Furthermore, when considering power consumption, a special characteristic is required as a ferrite that has the smallest amount of change in the operating temperature range, that is, it is desirable that the temperature coefficient of power loss be negative near room temperature.
[0019]
As the need for higher performance in this way increases, the demand for smaller product variations naturally increases, but industry demands allow for a minimum cost increase and are uniform and stable. The demands must be satisfied by investigating the manufacturing means. Therefore, since it is not possible to obtain products with sufficient target characteristics and costs by simply adjusting and balancing mainly by specifying the composition components as in the past, it is necessary to study and elucidate the confounding requirements from various aspects at the same time. became.
[0020]
The present invention provides a method for producing soft ferrite in which the core loss of ferrite is reduced by controlling phosphorus and boron mixed in the ferrite raw material and in the production process to a specific amount and further performing firing under appropriate conditions. For the purpose.
[0021]
[Means for Solving the Problems]
In the method for producing soft ferrite according to claim 1 of the present invention, the total amount of phosphorus and boron mixed in the raw material and in the production process is 0.004 wt% or less (excluding zero), and the amount of boron is 0.002 wt% or less (excluding zero), phosphorus amount to a specific amount of 0.002 wt% or less Refined to produce ferrite material When firing the material, the oxygen partial pressure of the atmosphere in the temperature rising portion from 900 ° C. to the firing temperature is set to 15% or less (excluding zero), and the firing temperature is set to 1250 ° C. or more and 1400 ° C. or less. Has been. Preferably, the sum of boron and phosphorus is 0.0035 wt% or less (excluding zero), the amount of boron is 0.002 wt% or less (excluding zero), and the amount of phosphorus is 0.0015 wt% or less. More preferably, the sum of the amount of boron and phosphorus is 0.0025 wt% or less (excluding zero), the amount of boron is 0.0015 wt% or less (excluding zero), and the amount of phosphorus is 0.001 wt%. The following is desirable.
[0022]
In the method for producing ferrite according to claim 2 of the present invention, the total amount of phosphorus and boron mixed in the raw material and in the production process is 0.004 wt% or less (excluding zero), and the amount of boron is 0.002 wt%. % Or less (excluding zero) and the amount of phosphorus is 0.002 wt% or less, and the main component is 30 to 41 mol% manganese oxide in terms of MnO and 6 to 16 mol% zinc oxide in terms of ZnO. And the remainder is iron oxide, containing 0.005 to 0.025 wt% silicon in terms of SiO2 and 0.02 to 0.15 wt% calcium in terms of CaO, and 0.06 wt% or less in terms of Nb2 O5 Niobium (not including zero), 0.08 wt% or less in terms of V2 O5 (not including zero), zirconium in 0.07 wt% or less (not including zero) in terms of ZrO2, 0.4 wt in terms of SnO2 % Or less (excluding zero) of tin and TiO2 It contains one or more of 0.3 wt% or less (excluding zero) of titanium, and part or all of its constituent elements or additives are mixed in a solution, and ferrite is produced by spray roasting. ing.
[0023]
[Action]
According to the method for producing soft ferrite according to claim 1 of the present invention, since the allowable region of the production condition for obtaining the low magnetic core loss at high frequency and high magnetic flux density of the soft magnetic ferrite becomes narrower as the amount of phosphorus and boron increases, the raw material The total amount of phosphorus and boron mixed in and in the manufacturing process is 0.004 wt% or less (excluding zero), the amount of boron is 0.002 wt% or less (excluding zero), and the amount of phosphorus is 0 To specific amount of less than 0.002 wt% Refined to produce ferrite material When firing the material, the oxygen partial pressure in the temperature rising portion from 900 ° C. to the firing temperature is 15% or less (excluding zero), and the firing temperature is 1250 ° C. or more and 1400 ° C. or less. As a result, the manufacturing process area can be expanded, and soft magnetic ferrite with high reproducibility and low loss at high frequency and high magnetic flux density can be obtained.
[0024]
According to the method for producing soft ferrite according to claim 2 of the present invention, among the manganese zinc-based ferrites, a material having a relatively high magnetic permeability and a low loss at a high frequency and a high magnetic flux density can be obtained stably.
[0025]
【Example】
At first glance, the present invention is easily received as “improvement of ferrite characteristics by a minor component composition” of the prior art, but as described above, a new “low loss at 100 KHz or more, low loss in a strong magnetic field”, and It was derived from a multifaceted investigation of difficult issues.
[0026]
The specific means is “to keep the amount of trace impurities that rapidly grow crystal grains low (purify when exceeding a certain amount)” and “oxygen from the beginning of crystallization, that is, from the time of sintering temperature rise. This is achieved by adopting the process of “reducing partial pressure”. In particular, it is important to pay attention to the fact that it does not act effectively after crystal growth is completed in order to reduce the loss at a high frequency of 100 KHz or higher.
[0027]
In the following, this means will be described in detail. In general, a high-purity main component material is used to produce high-performance ferrite, and the crystal structure is controlled by a trace composition and additives, but there are few impurities in the starting material. If it is better to select one with a small amount of all impurities, the quality cost cannot be balanced and it cannot be used industrially. For this purpose, as will be described later, components for adjusting grain boundary oxidation, such as Si and Ca, are also added in a relatively large amount. It can be solved by adjusting the crystal state as a whole.
[0028]
However, in order to target ultra-high quality low-loss materials as in the present invention, the presence or absence of extremely small amounts of phosphorus and boron, 1/10 to 1/100 of these additives, makes it impossible to solve the problem. With regard to these two components, variation in problem solving effects is suppressed by selecting and correcting raw materials having particularly low contents.
[0029]
Phosphorus and boron are components that rapidly change the sintering characteristics even in trace amounts, and react with the ferrite main component to form a liquid phase, which generally forms an inhomogeneous fine crystal structure and deteriorates magnetic properties. It is thought that Therefore, in order to obtain magnetic properties with high permeability and low loss at high frequencies, it is necessary to positively select a raw material source with a low content of these two components.・ A region where interaction with additive components and sintering conditions can be used cannot be obtained.
[0030]
According to the present invention, when each component is independent, it is 0.002 wt% for phosphorus, 0.002 wt% for boron, and when the two components coexist, the interaction is lost when the content is 0.004 wt% or more. It has been found that the amount is a limit amount that promotes crystal growth so rapidly that the magnetic properties cannot be adjusted even if other manufacturing requirements including additives are changed. Therefore, in order to solve the problem, at the time of selecting the main component raw material, at least 0.002 wt% (excluding zero) for boron, 0.002 wt% or less for phosphorus, and a total of 0. Select 004 wt% or less (excluding zero), and adjust to a specific amount below the above limit amount in consideration of the amount of contamination. Preferably, the sum of boron and phosphorus is 0.0035 wt% or less (excluding zero), the amount of boron is 0.002 wt% or less (excluding zero), and the amount of phosphorus is 0.0015 wt% or less. More preferably, the sum of the amount of boron and phosphorus is 0.0025 wt% or less (excluding zero), the amount of boron is 0.0015 wt% or less (excluding zero), and the amount of phosphorus is 0.001 wt%. The following is desirable.
[0031]
Further, as described above, various impurities may be contained in addition to these two components, and the fine structure changes depending on the type and amount, and thus often acts as a characteristic adjusting or improving component. In particular, in order to obtain high performance, the allowable amount of impurities is generally small as described above, but CaO and SiO2 are typical impurities for manganese zinc ferrite and are also known as adjusting additives.
[0032]
In general, when the amount of CaO increases, the low frequency μi gradually decreases, and the high frequency μi increases, but has an appropriate range in which it decreases below 0.025 wt%. In addition, it is considered that CaO is segregated at the grain boundaries and oxidized to contribute to a reduction in loss and improved. Similarly, segregation is observed for SiO2, but if the amount is too large, abnormal growth occurs, the specific resistance is lowered, and the improvement effect is reduced. Therefore, it is known that it is desirable to adjust the addition amount according to the target characteristics within the range of CaO of 0.25 wt% or less and SiO2 of 0.02 wt% or less including the amount in the raw material. It has been clarified that the region and the degree to which the effect is obtained are premised on the contents of phosphorus and boron and the firing conditions.
[0033]
The minimum amount of CaO and SiO2 is determined by the content in the raw material and the purpose of adjustment. It is known that if SiO2 and CaO are segregated at the grain boundaries, they are easily affected by the firing atmosphere, particularly the amount of oxygen, but if only the grain boundaries are oxidized, the specific resistance of the grain boundaries can be increased. However, in this respect as well, when phosphorus and boron exceed the limit values, in other words, if the crystal grows too rapidly, it is a means to obtain a low loss that cannot be achieved by the prior art. It is a new finding that the effect of improving characteristics cannot be expected.
[0034]
Also, the grain boundary itself and the distance between crystal grains are closely related to the magnetic properties, but they deteriorate even if they are partly too large. Therefore, the grain boundary forming substances such as Si and Ca need to be added in a dispersed state. More desirable results were obtained by spray sintering simultaneously with the main component if necessary. Furthermore, the characteristics required for the ferrite field for high-frequency power sources are basically high Bs and large ΔB, that is, low Br. Naturally, the characteristic is mainly high saturation magnetic flux density and high permeability. It is necessary to select a main component region that can also serve as a magnetic susceptibility.
[0035]
Therefore, a range in which 30 to 41 mol% manganese oxide in terms of MnO, 6 to 16 mol% zinc oxide in terms of ZnO, and the remainder being iron oxide is suitable. Outside this range, the core loss increases, the minimum temperature of the core loss becomes 60 ° C. or less, the Curie temperature becomes 200 ° C. or less, the initial permeability decreases, the residual magnetic flux density (Br) Or increase. Further, as fine-tuning balancing additives, in addition to the above SiO2 and CaO, niobium of 0.06 wt% or less in terms of Nb2 O5, vanadium of 0.08 wt% or less in terms of V2 O5, zirconium in terms of ZrO2 of 0.07 wt% or less, SnO2 Adjust by adding one or more of 0.4 wt% or less of tin in terms of TiO2 and 0.3 wt% or less of titanium in terms of TiO2. When Nb2 O5 exceeds 0.06 wt%, the core loss increases and the initial permeability decreases. When V2 O5 exceeds 0.08 wt%, the core loss increased and the initial permeability decreased. When ZrO2 exceeded 0.07 wt%, the core loss increased and the initial permeability decreased. When SnO2 exceeds 0.4 wt%, the minimum temperature of the core loss becomes 60 ° C. or less. When TiO2 exceeds 0.3 wt%, the minimum temperature of the core loss becomes 60 ° C. or less. In selecting this type of starting material, not only the control and correction of the composition components including the additive of the present invention, but also other impurities such as Sr and Ba are reduced to 0.05 wt% or less in total. It is desirable to hold down so as not to reduce the effect.
[0036]
Select a starting material with extremely low amounts of phosphorus and boron, which are rapid crystallization accelerating components, and make corrections in consideration of the amount of contamination, or if necessary, provide dephosphorization and deboronation processes, In the case of coexistence, the adjustment process is provided so that the total content is 0.002 wt% or less (excluding zero), and in the case of coexistence, the total content is 0.004 wt% or less (excluding zero). Preferably, the sum of boron and phosphorus is 0.0035 wt% or less (excluding zero), the amount of boron is 0.002 wt% or less (excluding zero), and the amount of phosphorus is 0.0015 wt% or less. More preferably, the sum of the amount of boron and phosphorus is 0.0025 wt% or less (excluding zero), the amount of boron is 0.0015 wt% or less (excluding zero), and the amount of phosphorus is 0.001 wt%. The following is desirable. In the adjustment process, after suppressing the rapid growth of the ferrite crystal, the low oxygen partial pressure is reduced during the temperature rise of sintering, thereby reducing the high frequency loss and adjusting the desired characteristics, ie, Ca, Si. , Nb, V, Sn, Ti, etc. are found to be widened in the field of production conditions where they are effective and stable.
[0037]
If boron and phosphorus, which rapidly accelerates crystal growth, are less than the above-mentioned limit amounts, the core loss peak of about 30% can be improved by selecting the temporary particle size, and mixing between solutions such as solution mixing As shown in Fig. 3, the improvement effect of the core loss by the low oxygen partial pressure in the heating part (from 900 ° C to the sintering temperature) is shown in Fig. 2. As shown, it became clear that the effect of the additive can be effectively and stably brought out within the range of the firing temperature (1250 ° C. or higher and 1400 ° C. or lower).
[0038]
These actions and effects are easy to identify with the prior art because the problems are similar at first glance. However, phosphorous is a prerequisite for controlling the degree of crystal growth, such as atomic energy that can be controlled as electric power and atomic energy as a bomb. And boron act as limit amounts. Therefore, when all of the trends shown in the prior art show the opposite tendency, for example, the relationship between the amount of oxygen and phosphorus during the temperature increase described above also appears. This is different from general chemical substances in which the electrical and magnetic properties are determined immediately after the composition components are determined, because of the inherent properties of solid solutions, which are a kind of mixture. Among the basic composition / components, crystallization promoting components, and property adjusting components, it is possible to supply a stable and large amount (which can increase the process quality capability Cp), especially by keeping boron / phosphorus, which are strong crystallization promoting components, low. It is thought that the incident could be set.
[0039]
Therefore, this is different from the conventional technical idea of improving the characteristics due to the “effect by adding (amount)” of boron and phosphorus. As a result of investigating the interaction between the two, it seems that it looks similar at first glance, but new knowledge specific to solid solutions has been obtained. The difference in the claims and the detailed explanation that cannot be understood between the above-mentioned prior arts and the like supports this. In addition, even if a part or all of the component structure is mixed in a solution and further uniformed by spray roasting to achieve uniform mixing, the tendency of the basic action and effect depending on the composition component and the added amount does not change. The optimum value as a high-frequency power supply material can be obtained by adjusting some manufacturing conditions.
[0040]
[Example 1]
A mixture of FeCl2 and MnCl2 having different phosphorus and boron contents is subjected to oxidation roasting to a mixture of iron oxide and manganese oxide, and zinc ferrite (ZnFe2 O4), SiO2, CaCO3, Nb2 O5 and V2 O5 are added. MnZn ferrite material was prepared by adding, mixing and grinding.
To these ferrite materials, a binder was added and pressure-formed into a toroidal shape, followed by firing in an atmosphere in which air and nitrogen gas were mixed.
The core loss of the ferrite core obtained as described above is shown in FIGS. The core loss was reduced under the conditions of low phosphorous and boron content and firing conditions with a low oxygen partial pressure in the temperature raising section.
[0041]
[Example 2]
Zinc ferrite (ZnFe2 O4), SiO2, CaCO3, Nb2 O5, V2 O5, SnO2 and TiO2 are added to a mixture of iron oxide and manganese oxide obtained by oxidizing and roasting a mixed solution of FeCl2 and MnCl2. After mixing and pulverization, No. 1 shown in Table 1 was obtained. Samples 1-9 were prepared.
These samples were press-molded into a toroidal shape by adding a binder, and then subjected to main firing at 1320 ° C. for 4 hours in an atmosphere in which air and nitrogen gas were mixed.
Table 1 shows the core loss of the ferrite core obtained as described above. Core loss was reduced in samples with low phosphorus and boron content (0.0005 wt% each of phosphorus and boron) and one or more of Nb2 O5, V2 O5, ZrO2, SnO2 and TiO2.
[0042]
[Example 3]
After adding Si, Ca, Nb, Zr, and Sn in a mixed form of FeCl2 and MnCl2 in a chloride or soluble form, oxidation roasting was performed to obtain a mixture of iron oxide and manganese oxide. This was mixed with zinc ferrite (ZnFe2 O4) and pulverized. Ten samples were made.
To this sample, a binder was added and pressure-molded into a toroidal shape, followed by firing at 1320 ° C. for 4 hours in an atmosphere in which air and nitrogen gas were mixed.
[0043]
Table 1 shows the core loss of the ferrite core obtained as described above. No. in which trace components were added after roasting. Compared to the sample of No. 9, The core loss was further reduced with 10 samples.
[0044]
[Table 1]

[0045]
【The invention's effect】
According to the present invention, the content of boron and phosphorus, including the amount of contamination and the amount of contamination, is 0.0020 wt%, 0.0020 wt% or less, and the sum is controlled to 0.004 wt% or less (excluding zero), Fe2 O3, MnO , And ZnO as a main component, and 0.002 to 0.025 wt% of Si in terms of SiO2 as subcomponents and 0.02 to 0.15 wt% of Ca in terms of CaO, and 0.05 wt in terms of Nb2 O5 as an additive. By adding at least one of V below 0.05 wt% in terms of V2 O5, Sn less than 0.4 wt% in terms of SnO2 and Ti and up to 0.3 wt% in terms of TiO2 A power supply can be realized.
[Brief description of the drawings]
FIG. 1 is a graph showing changes in core loss depending on phosphorus and boron contents in ferrite.
FIG. 2 is a graph showing changes in core loss depending on phosphorus content and firing temperature.
FIG. 3 is a graph showing changes in core loss due to phosphorus content and oxygen partial pressure in a firing temperature raising portion.

Claims (2)

The sum of the amount of phosphorus and boron mixed in the raw materials and in the manufacturing process is 0.004 wt% or less (excluding zero), the amount of boron is 0.002 wt% or less (excluding zero), and the amount of phosphorus is A ferrite material is produced by refining to a specific amount of 0.002 wt% or less, and when firing the material, the oxygen partial pressure in the temperature rising portion from 900 ° C. to the firing temperature is 15% or less (excluding zero) And a firing temperature of 1250 ° C. or higher and 1400 ° C. or lower. In producing the soft ferrite material according to claim 1, the main component is manganese oxide of 30 to 41 mol% in terms of MnO, 6 to 16 mol% of zinc oxide in terms of ZnO, and the remainder is iron oxide, and the amount is 0.002 in terms of SiO2. It contains 0.005 to 0.025 wt% silicon and 0.02 to 0.15 wt% calcium in terms of CaO, and 0.06 wt% or less niobium in terms of Nb2 O5 (excluding zero), and 0.02 in terms of V2 O5. Less than 08wt% (excluding zero) vanadium, ZrO2 converted 0.07wt% (excluding zero) zirconium, SnO2 converted 0.4wt% or less (excluding zero) tin and TiO2 converted Soft ferrite characterized in that it contains one or more of 0.3 wt% or less (excluding zero) of titanium and is produced by spray roasting by mixing part or all of its constituent elements or additives with a solution. Production method.

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