CN105837192B

CN105837192B - NiMnZn-based ferrite

Info

Publication number: CN105837192B
Application number: CN201510947518.0A
Authority: CN
Inventors: 加藤充次; 浅枝勉
Original assignee: Enjie Electronic Parts Co ltd
Current assignee: Enjie Electronic Parts Co., Ltd.
Priority date: 2015-02-03
Filing date: 2015-12-17
Publication date: 2021-03-12
Anticipated expiration: 2035-12-17
Also published as: JP2016141602A; JP6472674B2; CN105837192A

Abstract

The invention provides a NiMnZn ferrite which can greatly reduce the frequency of about 2MHzSince the magnetic loss is smaller than that of the conventional one, the size of the inductor can be reduced. Contains as main components: with Fe₂O₃54 to 56 mol% of iron oxide, 5 to 8 mol% of zinc oxide in terms of ZnO, 2 to 4 mol% of nickel oxide in terms of NiO, and the balance of manganese oxide (MnO), and further comprising, as minor components, with respect to the main component: with CaCO₃0.08 to 0.18wt% of calcium in terms of SiO₂0.001 to 0.007wt% of silicon in terms of TiO₂0.3 to 0.6wt% of titanium in terms of Co₂O₃0.3 to 0.6wt% of cobalt calculated as ZrO₂0.03 to 0.07wt% in terms of zirconium and Sb₂O₃0.05 to 0.12wt% antimony in terms of conversion.

Description

NiMnZn-based ferrite

Technical Field

The present invention relates to a NiMnZn-based ferrite which can reduce magnetic loss at a frequency of about 2MHz and is therefore suitable for use in an iron core (core) of a transformer or the like of a high-frequency switching power supply.

Background

In an inductive element such as a transformer used in a high-frequency switching power supply, Fe is widely used as a main component in view of the necessity of securing characteristics such as curie temperature and saturation magnetic flux density required for the application₂O₃A MnZn ferrite composed of 50 to 56 mol%, ZnO 3 to 25 mol%, and the balance MnO, wherein various accessory components are added to the MnZn ferrite, thereby reducing loss.

Among the MnZn-based ferrite, especially, NiMnZn-based ferrite to which NiO is added has a characteristic of small core loss (magnetic loss) at a high frequency of 2MHz or more, and patent document 1 below proposes a NiMnZn-based ferrite containing, as subcomponents: with CaCO₃800-3000 ppm of calcium calculated as SiO₂100 to 1000ppm of silicon and Nb₂O₅The average grain size of ferrite grains is 2.1 to 8.1 μm in terms of 520 to 1000ppm of niobium.

According to the following patent document 1, the NiMnZn-based ferrite having the above-described configuration can be configured, as a preferable aspect: the magnetic loss Pcv measured at 2MHz, 50mT, 100 ℃ was 2700kw/m³The following.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2010-83692.

Disclosure of Invention

However, in response to recent demands for miniaturization of such an inductive element, further reduction of magnetic loss is strongly desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a NiMnZn-based ferrite which can significantly reduce magnetic loss at a frequency of about 2MHz, and therefore can realize a smaller core and a smaller size of an induction element than the conventional one.

In order to solve the above-mentioned problems, the invention according to claim 1 is a NiMnZn-based ferrite, characterized in that,

contains as main components: with Fe₂O₃54 to 56 mol% of iron oxide in terms of ZnO, 5 to 8 mol% of zinc oxide in terms of ZnO, 2 to 4 mol% of nickel oxide in terms of NiO, and the balance of manganese oxide (MnO),

and, as a subcomponent, the following components are contained in the main component: with CaCO₃0.08 to 0.18wt% of calcium in terms of SiO₂0.001 to 0.007wt% of silicon in terms of TiO₂0.3 to 0.6wt% of titanium in terms of Co₂O₃0.3 to 0.6wt% of cobalt calculated as ZrO₂0.03 to 0.07wt% in terms of zirconium and Sb₂O₃0.05 to 0.12wt% antimony in terms of conversion.

When an iron core is formed from the NiMnZn-based ferrite according to claim 1, it is preferable to control the sintering temperature and the like so that the sintered density becomes 4.8g/cm from the viewpoint of preventing the occurrence of cracks and chips in the product³The above.

In the invention according to claim 1, Sb is added as a subcomponent to the NiMnZn-based ferrite in a predetermined range, and sintering is performed at a low temperature to suppress grain growth, thereby reducing the initial permeability. Accordingly, the resonance frequency shifts to the high frequency side, and the core loss at high frequency can be reduced.

Further, according to the present invention, as seen from the results of examples described later, the core loss (2MHz-50mT) at 100 ℃ can be reduced to 600 kW/m³The following. As a result, the core is made smaller than before, and the size of the inductive element can be reduced.

Here, in the region of room temperature to 150 ℃, in order to make the magnetic anisotropyThe core loss is reduced by making the core smaller, and it is necessary to contain Fe as a main component₂O₃54 to 56 mol% of iron oxide in terms of ZnO, 5 to 8 mol% of zinc oxide in terms of ZnO, and nickel oxide in a range of 2 to 4 mol% in terms of NiO, with the balance being manganese oxide (MnO). If the nickel oxide is less than 2mol% in terms of NiO, the effect of reducing the core loss at high frequencies is reduced.

Further, since Ti in the subcomponent has an effect of increasing the resistance in the crystal grains, the core loss can be reduced by adding the amount within the above range, but the upper limit is TiO₂The reason why the conversion is set to 0.6wt% is that if this value is exceeded, the core loss becomes poor over the entire temperature range.

Further, both Ca and Si are components contributing to high resistance of the grain boundaries, and the core loss can be reduced by adding the amount within the above range. In addition, Co has an effect of stabilizing a magnetic domain wall due to Co-specific anisotropy, and the core loss at high frequencies can be reduced by adding Co in an amount within the above range. In addition, if Co is used₂O₃If the amount is less than 0.3wt%, the above-mentioned effects cannot be sufficiently obtained, and if it exceeds 0.6wt%, the core loss in the low temperature range is deteriorated.

Drawings

FIG. 1 is a graph showing the results of an embodiment of the present invention.

Detailed Description

One embodiment of the NiMnZn-based ferrite of the present invention will be described below.

The NiMnZn ferrite contains Fe as main component in the range of room temperature to 150 ℃ for reducing the magnetic anisotropy and restraining the core loss to a low level₂O₃54 to 56 mol% of iron oxide in terms of ZnO, 5 to 8 mol% of zinc oxide in terms of ZnO, and 2 to 4 mol% of nickel oxide in terms of NiO, and the balance being manganese oxide (MnO).

The NiMnZn-based ferrite contains, as sub-components, the following components with respect to the main component: with CaCO₃0.08 to 0.18wt% of Ca in terms of SiO₂0.001 to 0.00 in conversion7wt% Si, in TiO₂0.3 to 0.6wt% of Ti in terms of Co₂O₃0.3 to 0.6wt% of Co in terms of ZrO₂0.03 to 0.07wt% in terms of Zr and Sb₂O₃0.05 to 0.12wt% Sb is calculated so that the sintered density becomes 4.8g/cm³Calcination was performed in the above manner.

According to the NiMnZn ferrite having the above constitution, the core loss (2MHz-50mT) at 100 ℃ can be reduced to 600 kW/m as described later³The following.

Examples

First, a main component raw material as a main component is weighed so as to contain Fe₂O₃55 mol% of iron oxide, 36 mol% of manganese oxide in terms of MnO, 6 mol% of zinc oxide in terms of ZnO and 3 mol% of nickel oxide in terms of NiO.

Subsequently, the weighed raw materials were wet-mixed for 5 hours using a ball mill, then calcined at 850 ℃ for 2 hours in the air, and then pulverized again using a ball mill. Then, Sb was added to the powder as a subcomponent of the raw material as shown in FIG. 1₂O₃、Co₂O₃、CaCO₃、SiO₂、TiO₂、ZrO₂The particles were granulated with PVA and then molded into a ring shape (toroidal) with a die.

The addition amounts of the subcomponents shown in FIG. 1 are all in units of wt%. Subsequently, the compact was subjected to edge sintering at 1170 ℃ under oxygen control to prepare a ferrite sintered body. FIG. 1 shows the core loss Pcv (kW/m) of the sample obtained as described above under the condition of 2MHz to 50mT³) And a sintered density d (g/cm)³)。

As shown in FIG. 1, according to examples 1 to 18 of the present invention, the sintered density can be 4.8g/cm³Calcination was carried out in the above manner, and the core loss at 100 ℃ (2MHz-50mT) could be reduced to 600 kW/m³Hereinafter, in examples 1 to 18 of the present invention, CaCO was contained as a subcomponent with respect to iron oxide, zinc oxide, nickel oxide, and manganese oxide as main components₃0.08 to 0.18wt% of Ca in terms of SiO₂0.001 to 0.007wt% of Si in terms of TiO₂0.3 to 0.6wt% of Ti in terms of Co₂O₃0.3 to 0.6wt% of Co in terms of ZrO₂0.03 to 0.07wt% in terms of Zr and Sb₂O₃0.05 to 0.12wt% Sb.

In contrast, in comparative examples 1 to 3 in which the Sb content was less than the above range, the sintered density was 4.8g/cm³Hereinafter, it is found that the core loss (2MHz-50mT) reaches 600 kW/m in comparative example 4 in which the Sb content exceeds the above range, although a sufficient sintered density cannot be obtained³The above.

It is also understood that the core loss (2MHz-50mT) reached 600 kW/m in both comparative example 5 and 6 in which the Co content was less than the above range and comparative example 7 and 8 in which the Ca content was less than the above range³The above.

Furthermore, it was found that the core loss (2MHz-50mT) could not be reduced to 600 kW/m in both comparative example 9 and 10 in which the content of Si was less than the above range, comparative example 11 and 12 in which the content of Ti was less than the above range, and comparative example 13 and 14 in which the content of Zr was less than the above range³The following.

From the above test results, it was found that the NiMnZn-based ferrite of the present invention had a sintered density of 4.8g/cm³In the case where calcination is performed in the above manner, the core loss (2MHz-50mT) at 100 ℃ can be reduced to 600 kW/m³The following.

Claims

A NiMnZn ferrite characterized by containing a metal element,

as a main component, made of Fe₂O₃54 to 56 mol% of iron oxide in terms of ZnO, 5 to 8 mol% of zinc oxide in terms of ZnO, 2 to 4 mol% of nickel oxide in terms of NiO, and the balance of manganese oxide MnO,

and, as a subcomponent, the following components are contained in the main component: with CaCO₃0.08 to 0.18wt% of calcium in terms of SiO₂Conversion0.001 to 0.007wt% of silicon in terms of TiO₂0.3 to 0.6wt% of titanium in terms of Co₂O₃0.3 to 0.6wt% of cobalt calculated as ZrO₂0.03 to 0.07wt% in terms of zirconium and Sb₂O₃0.05 to 0.12wt% antimony in terms of conversion.