JP2006143530A - Ni-Zn BASED FERRITE COMPOSITION AND MAGNETIC ELEMENT - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve superposition characteristic when a magnetic element is structured by balancing the improvement of initial magnetic permeability and saturation flux density and increasing magnetic field to be applied until magnetic flux is saturated. <P>SOLUTION: The Ni-Zn based ferrite composition comprises 49.0-50.0 mol% iron oxide (Fe<SB>2</SB>O<SB>3</SB>), 21.0-30.0 mol% mixture of nickel oxide (NiO) with copper oxide (CuO) (wherein the replacement ratio of copper oxide is 5.00-30.00%) and balance being zinc oxide (ZnO). The Ni-Zn based ferrite composition contains 100-800 ppm calcium oxide (CaO) and 1,000-2,000 ppm aluminum oxide (Al<SB>2</SB>O<SB>3</SB>) to total weight of each component as additives of the ferrite. The magnetic element uses the ferrite composition. A sintered compact (No.1-8) containing Al<SB>2</SB>O<SB>3</SB>and CaO has low rising of initial magnetization curve and is capable of increasing the magnetic field to be applied until the magnetic flux is saturated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a Ni—Zn-based ferrite composition having excellent magnetic characteristics and a magnetic element comprising the composition.

  In general, a power source inductor element is required to have excellent superposition characteristics when a current is applied. At present, many means for providing a gap at a portion where the magnetic paths in the inductor element are orthogonal to each other are employed. However, the provision of the gap improves the superimposition characteristics, but has the disadvantage that the inductance decreases. The decrease in inductance necessitates an increase in the number of turns of the coil to compensate for this, leading to an increase in the size of the inductor element. In recent years, as electronic devices typified by PCs have become smaller or thinner, there is a strong demand for smaller electronic components to be mounted. In view of such requirements, attempts have been made to improve the superposition characteristics by developing a material for the core material of the inductor element without providing a gap.

Recently, further improvements in magnetic properties such as initial magnetic permeability and saturation magnetic flux density have been desired for ferrite as a core material for inductor elements. Conventionally, Mn—Zn ferrites that are excellent in magnetic properties such as initial permeability and saturation magnetic flux density have been adopted, but in recent years, Ni—Zn ferrites that are excellent in terms of both insulating properties and manufacturing costs have been adopted. ing. For example, Patent Document 1 discloses an invention of a Ni—Zn ferrite having a high saturation magnetic flux density and excellent direct current superposition characteristics.
JP 2001-217115 (Claims etc.)

  However, the above Ni-Zn ferrite also has the following problems. In general, in order to improve the superposition characteristics of the inductor element, means for increasing the saturation magnetic flux density of the hysteresis curve is employed, but the initial permeability and the saturation magnetic flux density are in a reciprocal relationship. For this reason, simply increasing the saturation magnetic flux density lowers the initial permeability, and as a result, there is a problem in that the inductance is reduced when the magnetic element is configured.

  In view of such problems, the present invention maintains the balance between the improvement of the initial magnetic permeability and the saturation magnetic flux density, and further increases the magnetic field (current amount) that can be applied until the magnetic flux is saturated, thereby superimposing at the time of magnetic element configuration. The object is to further improve the characteristics.

To achieve the above object, the present invention is iron oxide _{(Fe 2} O 3) _{49.0~50.0mol%} and, mixtures 21.0～30.0Mol% of nickel oxide (NiO) and copper oxide (CuO) (Including a copper oxide substitution rate of 5.00 to 30.00%) and a balance of zinc oxide (ZnO) as a Ni-Zn based ferrite composition, The Ni—Zn ferrite composition contains 100 to 800 ppm of calcium oxide (CaO) and 1000 to 2000 ppm of aluminum oxide (Al ₂ O ₃ ) based on the total weight. The present invention also constitutes a magnetic element comprising such a composition. _Here, Fe ₂ O 3, NiO, each molar ratio of CuO and ZnO _is a numerical value when the Fe ₂ O 3, NiO, the total amount of CuO and ZnO and 100 mol%. Moreover, the amount of CaO and Al ₂ O ₃ is shown as a weight ratio to the total weight of Fe ₂ O ₃ , NiO, CuO and ZnO.

When the molar ratio of Fe ₂ O ₃ is smaller than 49.0 mol%, the core loss is increased, which is not preferable. On the other hand, when the molar ratio of Fe ₂ O ₃ is larger than 50.0 mol%, the specific resistance is lowered and the temperature characteristics are deteriorated. Accordingly, the content of _Fe 2 _{O 3} is preferably in the range of 49.0~50.0mol%.

   When the mixture of NiO + CuO has a lower limit of 21.0 mol%, assuming that the copper oxide substitution rate is 5.00%, NiO is 19.95 mol% and CuO is 1.05 mol%. If the copper oxide substitution rate is 30.00%, NiO is 14.7 mol% and CuO is 6.3 mol%.

  When the upper limit of the mixture of NiO + CuO is 30.0 mol%, assuming that the copper oxide substitution rate is 5.00%, NiO is 28.5 mol% and CuO is 1.5 mol%. Further, assuming that the copper oxide substitution rate is 30.00%, NiO is 21.0 mol% and CuO is 9.0 mol%.

  When the molar ratio of NiO is larger than 28.5 mol%, the balance between the saturation magnetic flux density and the initial magnetic permeability is lost. On the other hand, even if the molar ratio of NiO is smaller than 14.7 mol%, the balance between the saturation magnetic flux density and the initial magnetic permeability is similarly lost. For this reason, it is preferable that the molar ratio of NiO is in the range of 14.7 to 28.5 mol%.

  When the molar ratio of CuO is greater than 9.0 mol%, the saturation magnetic flux density decreases. On the other hand, when the molar ratio of CuO is smaller than 1.05 mol%, the firing temperature is increased. For this reason, it is preferable that the molar ratio of CuO exists in the range of 1.05-9.0 mol%. The copper oxide substitution rate is preferably in the range of 15.00 to 20.00%. Moreover, it is preferable that the molar ratio of the mixture of NiO + CuO exists in the range of 28-30 mol%.

On the other hand, if the content of Al ₂ O ₃ is less than 1000 ppm, the performance is almost the same as that of a conventional product not containing Al ₂ O ₃ . On the other hand, if the content of Al ₂ O ₃ exceeds 2000 ppm, the DC superimposition characteristic is improved, but the frequency characteristic becomes non-linear, which is not preferable. Therefore, the content of _Al 2 _{O 3} is preferably in the range of 1000-2000 ppm. In particular, the content of Al ₂ O ₃ is more preferably in the range of 1000 to 1500 ppm. Further, when only Al ₂ O ₃ is added, the superposition characteristics are improved, but other characteristics (initial permeability, temperature characteristics, etc.) are deteriorated. When CaO coexists with Al ₂ O ₃ , superposition characteristics and other characteristics are improved. If the CaO content is less than 100 ppm, it is difficult to keep the initial permeability low. Moreover, when there is more content rate of CaO than 800 ppm, the viscosity of a slurry will become high in a manufacturing process, and a bad influence will arise on handling. Therefore, the CaO content is preferably in the range of 100 to 800 ppm. In particular, the CaO content is more preferably in the range of 200 to 500 ppm.

  According to the present invention, the balance between the improvement of the initial magnetic permeability and the saturation magnetic flux density is maintained, and further, the superposition characteristics at the time of magnetic element configuration can be further improved by increasing the magnetic field that can be applied before the magnetic flux saturation. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  The Ni—Zn ferrite composition according to the embodiment of the present invention is suitable for a magnetic element. In this embodiment, an example in which a Ni—Zn ferrite composition is used as a magnetic element will be described.

  FIG. 1 is a flowchart showing a process for manufacturing a magnetic element.

  As shown in FIG. 1, the magnetic element includes a raw material mixing step (step S1), a granulation step (step S2), a calcining step (step S3), a sieving step (step S4), a crushing step (step S5), It is manufactured through a granulation process (step S6), a molding process (step S7), and a firing process (step S8). The core material is subjected to various evaluations after production in order to examine its performance. Hereinafter, each process for manufacturing a magnetic element will be described.

(Raw material mixing step: Step S1)
First, Fe ₂ O ₃ fine powder, NiO fine powder, CuO fine powder and ZnO fine powder are weighed, put into a ball mill mixer together with a predetermined amount of water and a dispersant, and the ball mill mixer is rotated.
(Granulation process: Step S2)
This step is a step performed to increase the molding density and the subsequent sintering density. After the mixing step, the slurry is transferred from the ball mill mixer to another container and mixed with a predetermined amount of binder using a stirrer. When foam comes out after adding the binder, add antifoaming agent. Moreover, when it is thought that a dispersing agent is insufficient, you may add a dispersing agent, stirring. Next, the slurry is put into a spray dryer and granulated.
(Calcination process: Step S3)
The granulated raw material is transferred from a spray dryer to a heat-resistant container and calcined at a temperature of about 800 ° C.
(Sieving process: Step S4)
Next, the raw material after calcination is passed through a 30 mesh (mesh size: about 500 microns) sieve to remove large particles.
(Crushing step: Step S5)
Next, the powder dropped from the sieve and depending on conditions, an additive (at least one of CaO fine powder, Al ₂ O ₃ fine powder, Cr ₂ O ₃ fine powder, etc.) is added, and a predetermined amount of water and dispersion are added. Together with the agent, it is put into a ball mill mixer and the ball mill mixer is rotated. The ball mill mixer contains iron balls, and the powder under the sieve and, depending on the conditions, the mixed powder with additives added are crushed and mixed in the ball mill mixer. During this process, periodically samples the slurry, at a 1.3 micron average particle size (D ₅₀ value), and terminates the disintegration and mixing. The particle size distribution of the crushed particles is measured by a laser method.
(Granulation process: Step S6)
Since the next granulation process is the same as the process of step S2, the description thereof is omitted.
(Molding process: Step S7)
Next, the granulated powder is put into a molding die and molded.
(Baking process: Step S8)
Next, the molded body is taken out from the mold and fired at a temperature of about 1100 ° C. under normal pressure (normal pressure sintering).

  In addition, the manufacturing method which consists of said each process is only one form in manufacturing the magnetic element of this invention, and can employ | adopt a process different from the above. In each step, a method different from the above can be adopted.

  For example, the calcining process (step S3), the sieving process (step S4), the crushing process (step S5) and the granulating process (step S6) are omitted from the process consisting of the above-described steps S1 to S8. You may employ | adopt the manufacturing method which consists of a mixing process (step S1), a granulation process (step S2), a shaping | molding process (step S3), and a baking process (step S4). When the particle size of the raw material to be charged in step S1 is large, the raw material mixing step (step S1) may also serve as a raw material pulverization step. Further, the sieving step is performed before the raw material mixing step, and from the sieving step (step S1), the raw material mixing step (step S2), the granulation step (step S3), the molding step (step S4), and the firing step (step S5). The following manufacturing method may be adopted. Furthermore, you may employ | adopt the manufacturing method which consists of a raw material mixing process (step S1), a granulation process (step S2), a sieving process (step S3), a shaping | molding process (step S4), and a baking process (step S5). Moreover, you may throw in an additive in a raw material mixing process (step S1).

A temperature lower or higher than 800 ° C. may be adopted as the temperature in the calcination step. However, even when a temperature higher than 800 ° C. is employed, the temperature is lower than the firing temperature in the firing step. Further, the sieve used in the sieving step is not limited to a 30-mesh net, and a finer mesh or a coarser net can be used. The sieve can be appropriately selected depending on the characteristics of the granulated powder, the particle size of the raw material used, and the like. Further, indication of the crushing ends in crushing step, the average particle diameter (D ₅₀ value) other than the guide, for example, a D ₉₀ value or D ₁₀ value when the maximum value of the particle size in particle size distribution was D ₁₀₀ It may be adopted. Further, even when employing a D ₅₀ value, it may be terminated disintegrated to measure a value other than 1.3 microns. This is because the degree of crushing can vary depending on the molding conditions and the density requirements of the sintered body. In the molding process, a method other than molding using a mold, for example, cold isostatic pressing (CIP) or the like may be employed. In the firing step, a method other than atmospheric pressure sintering, for example, a sintering method in which a pressure such as hot pressing or hot isostatic pressing (HIP) is applied may be employed. When such pressure sintering is employed, the sintering may be performed at a temperature lower than 1100 ° C. Further, the sintering temperature can be appropriately changed according to the pressure.

  Hereinafter, a method for evaluating a magnetic element will be described.

  Items that can be evaluated are initial permeability (μi), quality factor (Q), relative loss factor (tan δ / μiac), saturation magnetic flux density (Bs), core loss (Pcv), amplitude relative permeability (μa), relative The temperature coefficient (αμir) and the specific resistance (ρv).

  Here, the initial permeability (μi) refers to the limit value of the amplitude permeability of the magnetic core when the strength of the magnetic field is made as close to zero as possible. For this reason, the initial permeability (μi) indicates the response of the magnetic core to the external magnetic field. The quality factor (Q) is the reciprocal of the loss coefficient tan δ (the sum of hysteresis loss coefficient, eddy current loss coefficient, and residual loss coefficient). The relative loss coefficient (tan δ / μi) is a value obtained by dividing the loss coefficient (tan δ) by the AC initial permeability (μiac). The saturation magnetic flux density (Bs) refers to the maximum magnetic flux density possible in the magnetic material. Core loss (Pcv) refers to the energy consumed when moving in a magnetic hysteresis curve by an external magnetic field after a ferromagnetic material such as ferrite is magnetized. In general, the core loss (Pcv) is expressed as the sum of energy loss converted to heat and energy loss caused by eddy current. However, an insulator such as ferrite hardly generates eddy current. This is mainly equivalent to energy loss due to heat generation. Since the core loss is proportional to the area of the magnetic hysteresis curve, the smaller the area, the smaller the core loss. Amplitude relative permeability (μa) is the magnetic flux density when a magnetic field that periodically changes with time on a magnetic core in a state where no magnetic field is applied and whose average strength is zero is applied. The relative permeability obtained from the maximum value and the maximum value of the magnetic field strength. The relative temperature coefficient (αμir) refers to a coefficient represented by (μi2−μi1) / μi1 (T2−T1). Here, T1 and T2 indicate the temperature, and μi1 and μi2 indicate the initial permeability at the temperature T1 and the initial permeability at the temperature T2, respectively. Specific resistance (ρv) refers to the electrical resistance per unit volume of a substance.

  FIG. 2 is a diagram comparing the hysteresis curve (2A) of a conventional Ni—Zn ferrite sintered body and the hysteresis curve (2B) aimed at by the Ni—Zn ferrite sintered body of the present invention. In the present invention, the rise of the initial magnetization curve is suppressed to a low level, and it aims to be a hysteresis curve in which the magnetic field (current amount) that can be applied before the saturation magnetic flux density is reached.

  Examples of the present invention and comparative examples will be described below. First, the manufacturing method and the evaluation method in each example and each comparative example will be described, and then the evaluation result will be described with reference to the tables and drawings.

1. Manufacturing method and evaluation method [Example 1]
(1) Raw material and mixing treatment As component ratios in the sintered body, Fe ₂ O ₃ fine powder, NiO fine powder, CuO fine powder and ZnO fine powder were 49.40 mol%, 21.75 mol% and 7.25 mol%, respectively. Each raw material powder was weighed so that the total weight of the four raw material powders was 3 kg. The CuO substitution rate at this time was 25.00%. Subsequently, each raw material powder after weighing was put in an attritor together with 1,800 ml of pure water, about 20 cc of a dispersant made of special polycarboxylic acid ammonium salt and 17.5 kg of steel balls having a diameter of 4 mm. The slurry concentration at this time was 62.5% by weight. Thereafter, the attritor was rotated under the conditions of a rotation speed of 200 rpm and a mixing time of 30 minutes, and each raw material powder was wet mixed.

(2) Granulation After mixing raw materials using an attritor, the slurry in the attritor was transferred to a stainless steel container. Next, a diluted aqueous solution of a binder made of polyvinyl alcohol was put into the container, and mixed for 1 hour or more using a stirrer. The stirring speed of the stirrer was in the range of 100 to 150 rpm. The diluted aqueous solution of the binder was added so that the pure binder was 1% with respect to the total weight of the raw material powder. In this example, since the raw material powder was 3 kg and the concentration of the diluted aqueous solution of the binder was 10 wt% (the solid content of the binder was 10 wt% and the remaining 90 wt% was water), 300 g of the diluted binder aqueous solution was added. The slurry viscosity was adjusted to the range of 1000 to 2000 cps by the addition of the binder. Moreover, when foam | bubble came out after throwing in a binder, the antifoamer which consists of nonionic polyether was added suitably. Next, the slurry thus prepared was gradually supplied to a spray dryer to perform granulation. Granulation was performed using a spray dryer. The rotation speed of the spray dryer disk was 8000 rpm, and granulation was performed for about 1 hour.

(3) Calcination The granulated raw material was transferred from the spray dryer to an alumina container. Next, the said alumina container containing the granulated raw material was put into the batch type baking furnace. The calcination was controlled by a program in which the temperature was raised from room temperature at 200 ° C./hr, held at 800 ° C. for 2 hours, and lowered to room temperature at 100 ° C./hr.

(4) Sieve After the inside of the furnace had cooled, the alumina container was taken out, and the raw material after calcination was passed through a 30-mesh sieve to remove coarse particles.

(5) Crushing Next, the powder under the sieve and the additive 100 ppm CaO fine powder and 1000 ppm Al ₂ O ₃ fine powder are added so that the slurry concentration falls within the range of 63 to 65 wt%. Along with a predetermined amount of water and dispersant, it was put into an attritor. The amount of the additive is set to 100 ppm and 1000 ppm as a component in the sintered body. Thereafter, the amount of the additive is the same. The balls placed in the attritor were the same as in the first mixing and the same amount. Further, the rotation speed of the attritor was set to 200 rpm, and the pulverization was performed for about 1 hour. In the middle, the slurry was sampled to measure the particle size. When the average particle size was about 1.3 microns as a result of the particle size measurement, the attritor was stopped. A laser type particle size distribution measuring device was used for measuring the particle size.

(6) Granulation The conditions for granulation were the same as those described in (2). Here, duplicate explanation is avoided.

(7) Molding Next, the granulated powder was put into a cemented carbide mold having a diameter of 30 mm and a diameter of 20 mm, and molded by applying a pressure of 9.5 t. The weight of the powder used for molding was 7.20 g. In addition, a 20t press was used for molding.

(8) Firing Next, the compact was removed from the mold, placed in a horizontal tubular atmosphere furnace, and fired. Firing is performed at room temperature from 1.6 ° C./min to 500 ° C., from 500 ° C. to 3.2 ° C./min to 1089 ° C., held at 1089 ° C. for 2 hours, and 5.0 ° C./min. It was carried out while controlling with a program that lowered the temperature to room temperature. The obtained sintered body was referred to as Sample No. It was set to 1.

(9) Evaluation method Next, the characteristics of the sintered body were evaluated. μi, Q, tan δ / μi and αμir were determined using an impedance / gain phase analyzer. The measurement conditions were wire rod S1-UEW-0-30-NTL, number of turns 20T, f = 10 and 100 kHz, 0SC LV = 0.1V. Bs was obtained using a direct current magnetization characteristic automatic recording apparatus. The measurement conditions were the primary wire S1-SFBW-0-40-NTL, the number of turns 95T, the secondary wire S1-UEW-0-20-NTL, the number of turns 60T, the magnetic field 30 or 50 Oe. Pcv and μa were determined using a BH measuring device. The measurement conditions were wire S1-UEW-0-35-NTL (RED), the number of turns of 8T on the primary side and the secondary side, f = 130 kHz, Bm = 70 to 100 mT. Also, ρv was determined using a Digit Multimeter. In measurement, an In—Ga electrode was applied.

[Example 2]
It manufactured on the same conditions as Example 1 except the quantity of CaO having been 200 ppm. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 2.

[Example 3]
It manufactured on the same conditions as Example 1 except having made the quantity of CaO into 300 ppm. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 3.

[Example 4]
Manufactured under the same conditions as in Example 1 except that the amount of CaO was 500 ppm. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 4.

[Example 5]
Except that the amount of al ₂ O ₃ to 1500ppm were prepared under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 5.

[Example 6]
Manufactured under the same conditions as in Example 1 except that the amount of CaO was 200 ppm and the amount of Al ₂ O ₃ was 1500 ppm. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 6.

[Example 7]
Manufactured under the same conditions as in Example 1 except that the amount of CaO was 300 ppm and the amount of Al ₂ O ₃ was 1500 ppm. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 7.

[Example 8]
Manufactured under the same conditions as in Example 1 except that the amount of CaO was 500 ppm and the amount of Al ₂ O ₃ was 1500 ppm. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 8.

[Example 9]
As component ratios in the sintered body, Fe ₂ O ₃ fine powder, NiO fine powder, CuO fine powder, ZnO fine powder, CaO fine powder and Al ₂ O ₃ fine powder were 49.50 mol%, 26.10 mol%, 2.90 mol%, 21.50 mol%, 500 ppm, and 1500 ppm, and the above four kinds of raw material powder excluding additives were weighed so that the total weight was 3 kg. The CuO substitution rate at this time was 10.00%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 9.

[Example 10]
Production was performed under the same conditions as in Example 9, except that the NiO fine powder and the CuO fine powder were 24.65 mol% and 4.35 mol%, respectively. The CuO substitution rate at this time was 15.00%. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 10.

[Example 11]
Production was performed under the same conditions as in Example 9 except that the NiO fine powder and the CuO fine powder were 23.20 mol% and 5.80 mol%, respectively. The CuO substitution rate at this time was 20.00%. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 11.

[Example 12]
Production was performed under the same conditions as in Example 9, except that the NiO fine powder and the CuO fine powder were 21.75 mol% and 7.25 mol%, respectively. The CuO substitution rate at this time was 25.00%. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 12.

  Next, an example (comparative example) for comparison with the example of the present invention will be described.

[Comparative Example 1]
As component ratios in the sintered body, Fe ₂ O ₃ fine powder, NiO fine powder, CuO fine powder and ZnO fine powder are 48.90 mol%, 20.63 mol%, 6.88 mol% and 23.60 mol%, respectively. In addition, each raw material powder was weighed so that the total weight of the four kinds of raw material powders was 3 kg. The CuO substitution rate at this time was 25.01%. The CaO fine powder and Al ₂ O ₃ fine powder were not added at all. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 13.

[Comparative Example 2]
Manufacture was performed under the same conditions as in Comparative Example 1 except that NiO fine powder, CuO fine powder, and ZnO fine powder were 21.00 mol%, 7.00 mol%, and 23.10 mol%, respectively. The CuO substitution rate at this time was 25.00%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 14.

[Comparative Example 3]
It was manufactured under the same conditions as in Comparative Example 1 except that the NiO fine powder, CuO fine powder and ZnO fine powder were 21.38 mol%, 7.13 mol% and 22.60 mol%, respectively. The CuO substitution rate at this time was 25.01%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 15.

[Comparative Example 4]
Manufacture was performed under the same conditions as in Comparative Example 1, except that NiO fine powder, CuO fine powder, and ZnO fine powder were 21.75 mol%, 7.25 mol%, and 22.10 mol%, respectively. The CuO substitution rate at this time was 25.00%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 16.

[Comparative Example 5]
As component ratios in the sintered body, Fe ₂ O ₃ fine powder, NiO fine powder, CuO fine powder and ZnO fine powder were 49.20 mol%, 21.00 mol%, 7.00 mol% and 22.80 mol%, respectively. In addition, each raw material powder was weighed so that the total weight of the four kinds of raw material powders was 3 kg. The CuO substitution rate at this time was 25.00%. The CaO fine powder and Al ₂ O ₃ fine powder were not added at all. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 17.

[Comparative Example 6]
It manufactured on the same conditions as the comparative example 5 except having made NiO fine powder, CuO fine powder, and ZnO fine powder 21.38 mol%, 7.13 mol%, and 22.30 mol%, respectively. The CuO substitution rate at this time was 25.01%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 18.

[Comparative Example 7]
Manufacture was performed under the same conditions as in Comparative Example 5, except that NiO fine powder, CuO fine powder, and ZnO fine powder were 21.75 mol%, 7.25 mol%, and 21.80 mol%, respectively. The CuO substitution rate at this time was 25.00%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 19.

[Comparative Example 8]
As component ratios in the sintered body, Fe ₂ O ₃ fine powder, NiO fine powder, CuO fine powder and ZnO fine powder are 49.40 mol%, 20.63 mol%, 6.88 mol% and 23.10 mol%, respectively. In addition, each raw material powder was weighed so that the total weight of the four kinds of raw material powders was 3 kg. The CuO substitution rate at this time was 25.01%. The CaO fine powder and Al ₂ O ₃ fine powder were not added at all. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 20.

[Comparative Example 9]
Manufacture was performed under the same conditions as Comparative Example 8, except that NiO fine powder, CuO fine powder, and ZnO fine powder were 21.00 mol%, 7.00 mol%, and 22.60 mol%, respectively. The CuO substitution rate at this time was 25.00%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 21.

[Comparative Example 10]
Manufacture was performed under the same conditions as in Comparative Example 8, except that NiO fine powder, CuO fine powder, and ZnO fine powder were 21.38 mol%, 7.13 mol%, and 22.10 mol%, respectively. The CuO substitution rate at this time was 25.01%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. It was set to 22.

[Comparative Example 11]
Manufacture was performed under the same conditions as in Comparative Example 8, except that NiO fine powder, CuO fine powder, and ZnO fine powder were 21.75 mol%, 7.25 mol%, and 21.60 mol%, respectively. The CuO substitution rate at this time was 25.00%. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 23.

[Comparative Example 12]
As component ratios in the sintered body, Fe ₂ O ₃ fine powder, NiO fine powder, CuO fine powder, ZnO fine powder, CaO fine powder, Cr ₂ O ₃ fine powder and Al ₂ O ₃ fine powder were 49.40 mol, respectively. %, 21.75 mol%, 7.25 mol%, 21.60 mol%, 100 ppm, 300 ppm and 1000 ppm, and the above four kinds of raw material powder excluding additives were weighed so that the total weight was 3 kg. The CuO substitution rate at this time was 25.00%. The difference from Comparative Example 11 is only that CaO fine powder, Cr ₂ O ₃ fine powder and Al ₂ O ₃ fine powder were added. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 24.

[Comparative Example 13]
The difference from Comparative Example 11 is that only 1000 ppm Al ₂ O ₃ fine powder was added as a component ratio in the sintered body without adding CaO fine powder and Cr ₂ O ₃ fine powder. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 25.

[Comparative Example 14]
The difference from Comparative Example 11 is that only 2000 ppm Al ₂ O ₃ fine powder was added as a component ratio in the sintered body without adding CaO fine powder and Cr ₂ O ₃ fine powder. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 26.

[Comparative Example 15]
The difference from Comparative Example 11 is that only the 250 ppm Cr ₂ O ₃ fine powder was added as the component ratio in the sintered body without adding the CaO fine powder and the Al ₂ O ₃ fine powder. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 27.

[Comparative Example 16]
The difference from Comparative Example 11 is that only the 500 ppm Cr ₂ O ₃ fine powder was added as the component ratio in the sintered body without adding the CaO fine powder and the Al ₂ O ₃ fine powder. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 28.

[Comparative Example 17]
The difference from Comparative Example 11 is that only the 250 ppm CaO fine powder was added as the component ratio in the sintered body without adding the Cr ₂ O ₃ fine powder and the Al ₂ O ₃ fine powder. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 29.

[Comparative Example 18]
The difference from Comparative Example 11 is that only the CaO fine powder of 500 ppm was added as the component ratio in the sintered body without adding the Cr ₂ O ₃ fine powder and the Al ₂ O ₃ fine powder. Others were manufactured under the same conditions as in Example 1. The evaluation conditions were the same as those in Example 1. The obtained sintered body was referred to as Sample No. 30.

2. Evaluation Results Table 1 and FIGS. 3 to 6 show the evaluation results of the samples obtained under the above-described manufacturing conditions. In FIGS. 3 to 5, each curve is thick at a portion where Hm is low, because a large number of plotted points overlap. The series notation (sample No.) shown in FIGS. It corresponds to.

First, sample no. Based on 13 to 23, when the relationship between each main component in the Ni—Zn based ferrite sintered body containing none of Al ₂ O ₃ , CaO and Cr ₂ O ₃ , the initial magnetization characteristics and the saturation magnetic flux density is seen. Sample No. It was found that No. 23 has the best characteristics because the initial permeability can be kept low and the saturation magnetic flux density can be increased. Thereafter, the main components are designated as Sample No. 23, the addition effect of each additive of Al ₂ O ₃ , CaO and Cr ₂ O ₃ was examined.

3 shows a sample No. in Table 1. 23 and sample no. It is a graph which shows the initial magnetization characteristic of each sample of 1-8. From the results of FIG. _3, than the sintered body containing neither Al ₂ O 3, CaO and _Cr 2 _{O 3} (No.23 in Table 1), the sintered body containing _Al 2 _{O 3} and CaO (No. It was found that 1 to 8) had a lower initial magnetization curve. That is, when Al ₂ O ₃ and CaO are included, it has been found that the initial magnetization characteristics of the Ni—Zn-based ferrite sintered body can be kept low, and the amount of magnetic field that can be applied before magnetic flux saturation can be increased.

4 shows a sample No. in Table 1. 23-26, no. 4, no. 6 and no. 8 is a graph showing initial magnetization characteristics of each sample of No. 8; From the result of FIG. 4, when Al ₂ O ₃ , CaO and Cr ₂ O ₃ are included, the sintered body does not include any of Al ₂ O ₃ , CaO and Cr ₂ O ₃ (No. 23 in Table 1). It was found that the initial magnetization curve rises low. However, a sintered body containing Al ₂ O ₃ , CaO and Cr ₂ O ₃ (No. 24 in Table 1) and a sintered body containing only Al ₂ O ₃ without containing CaO and Cr ₂ O ₃ (table 1 and No. 25 and No. 26 in No. 1), the characteristics of the sintered body (No. 24 in Table 1) containing Al ₂ O ₃ , CaO and Cr ₂ O ₃ are only Al ₂ O _3. It was found that the characteristics were the same as those of a sintered body containing 1000 ppm (No. 25 in Table 1). It was also found that the sintered body containing 2000 ppm of Al ₂ O ₃ (No. 26 in Table 1) has a further lower initial magnetization characteristic. Further, sintered bodies containing Al ₂ O ₃ and CaO (Nos. 4, 6 and 8 in Table 1) are sintered bodies containing only Al ₂ O ₃ (No. 25 and No. 26 in Table 1). ) And Al ₂ O ₃ , CaO and Cr ₂ O ₃ (No. 24 in Table 1).

5 shows a sample No. in Table 1. 23, no. 30, no. 4 and no. 8 is a graph showing initial magnetization characteristics of each sample of No. 8; From the results shown in FIG. 5, it was found that the initial magnetization characteristics can be further reduced by increasing the Al ₂ O ₃ content while keeping the CaO content constant.

6 shows a sample No. in Table 1. 23, no. 2, No. 4, no. 6 and no. 8 is a graph showing superposition characteristics of each sample of 8; Compared to the superimposed characteristics of the sintered body (No. 23 in Table 1) that does not contain any of Al ₂ O ₃ , CaO, and Cr ₂ O ₃ , the sintered body (No. in Table 1) containing Al ₂ O ₃ and CaO. It was found that the superposition characteristics of .2, 4, 6, and 8) were better. In particular, in the sintered body (Nos. 6 and 8 in Table 1) containing 1500 ppm of Al ₂ O ₃ and 200 or 500 ppm of CaO, better superposition characteristics were obtained.

Next, in Table 1, sample No. From the comparison of 9 to 12, the relationship between the CuO substitution rate, the initial magnetization characteristics, and the saturation magnetic flux density was examined. While the contents of Al ₂ O ₃ and CaO were kept constant (Al ₂ O ₃ was 1500 ppm and CaO was 500 ppm), the main component ratio was varied to change only the CuO substitution rate. As a result, it was found that both the initial magnetization characteristics and the saturation magnetic flux density can be achieved at a CuO substitution rate of 15.00% or 20.00%. It was found that when the CuO substitution rate was increased to 25.00%, the initial magnetization characteristics were lowered.

As described above, from the results shown in Table 1 and FIGS. 3 to 6, Fe ₂ O ₃ is 49.50 mol%, the mixture of NiO + CuO is 29.00 mol% (however, the CuO substitution rate is 15.00 or 20.00%), Al It was found that the characteristics of the sintered body having ₂ O ₃ of 1500 ppm and CaO of 500 ppm were the best.

  The present invention can be used mainly in an industrial field in which a magnetic element of a power supply system, such as an inductor or a transformer, is manufactured or used.

It is a flowchart which shows the process which manufactures the magnetic element which concerns on embodiment of this invention. It is a figure which compares and shows the hysteresis curve (2B) of the conventional Ni-Zn type ferrite sintered compact, and the hysteresis curve (2B) aimed at by the Ni-Zn type ferrite sintered compact of this invention. Sample No. in Table 1 23 and sample no. It is a graph which shows the initial magnetization characteristic of each sample of 1-8. Sample No. in Table 1 23-26, no. 4, no. 6 and no. 8 is a graph showing initial magnetization characteristics of each sample of No. 8; No. in Table 1 23, no. 30, no. 4 and no. 8 is a graph showing initial magnetization characteristics of each sample of No. 8; No. in Table 1 23, no. 2, no. 4, no. 6 and no. 8 is a graph showing superposition characteristics of each sample of 8;

Claims (3)

Iron oxide (Fe ₂ O ₃ ) 49.0 to 50.0 mol%, nickel oxide (NiO) and copper oxide (CuO) mixture 21.0 to 30.0 mol% (including copper oxide substitution rate 5.00 to 30.00%) and the balance being zinc oxide (ZnO), a Ni—Zn based ferrite composition,
Ni-Zn characterized by containing 100 to 800 ppm of calcium oxide (CaO) and 1000 to 2000 ppm of aluminum oxide (Al ₂ O ₃ ) as additives to the ferrite with respect to the total weight of the above components. -Based ferrite composition. The copper oxide substitution rate is 15.00 to 20.00%, and includes 200 to 500 ppm of calcium oxide (CaO) and 1000 to 1500 ppm of aluminum oxide (Al ₂ O ₃ ). The Ni-Zn ferrite composition described.   A magnetic element using the Ni—Zn ferrite composition according to claim 1.

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