JPS60225406A - High strength oxide magnetic material - Google Patents

Abstract

PURPOSE:To prevent breakage etc. of a core at handling etc. in a machine by a method wherein an additive containing lithium oxide and tungsten oxide is added to a basic material of ferrite containing nickel, copper and zinc, or manganese and zinc. CONSTITUTION:A basic material of ferrite containing nickel, copper and zinc or ferrite containing manganese and zinc, is added additive containing 2-23mol% lithium oxide and 77-98mol% tungsten oxide to form 4-8% in weight. After mixing this material, performs temporary calcination at 750-850 deg.C and wet process pulverization by alcohol. Thereafter, the above material is formed in rectangular parallelepiped shape by a press forming machine and a rectangular parallelepiped magnet core, for instance, whose length is 25mm., width is 5mm. and height is 3mm., is obtained after calcination at 1,000-1,100 deg.C for 1-3hr. In such a manner, cracking and breaking etc. of the core, at the press of the coil automatic winding or the assembly, is reduced, and then yield rate is improved and production efficiency is increased.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides high-strength oxide magnetism having a composition in which appropriate amounts of lithium oxide and tungsten oxide are added to nickel-copper-zinc ferrite or manganese-zinc ferrite. It's about materials.

[Prior Art] Ferrite, which is an oxide magnetic material, is widely used as the magnetic core of various wire-wound parts such as transformers and inductor elements, and it is well known that it is incorporated into various electronic devices. In response to the miniaturization and cost reduction of electronic devices in recent years, there is a strong desire for miniaturization and cost reduction at the component level, and wire-wound components are no exception. In particular, this type of component has a ferrite core inside and requires winding work, so it tends to be larger than other components. In order to make wire-wound parts smaller and cheaper, it is important to make the ferrite core itself as small as possible, and to automate as much as possible by introducing robots and the like into the winding and other assembly work.

[Problems to be Solved by the Invention] For example, when attempting to automatically wind a ferrite core, the core is positioned by contacting the reference surface of the winding machine, the core is gripped by a gripping part, and the wire is wound around it. However, unlike manual work, machine work does not allow for "manipulation" and is prone to problems such as core cracking and core chipping due to rough handling and the application of large pressure and impact forces. In addition, from the perspective of making parts smaller and lighter, the core shape is designed to make the wall thickness as thin as possible in areas that are not related to electromagnetic characteristics, which accelerates the occurrence of core cracks. It was also one of the factors. If core cracking or core chipping occurs, even if the wire is wound and assembled, the winding component will be defective, resulting in a large loss in terms of both manufacturing efficiency and cost.

One way to solve these problems is to improve the mechanical strength of the core so that it will not be damaged even if it is handled roughly by a robot or the like. There is a strong demand for high-strength materials, and various efforts have been made to improve compositions, manufacturing methods, etc., but these have not always been fully satisfactory depending on the application.

The present invention was made in consideration of the actual state of the prior art, and aims to be inexpensive and easy to manufacture, and to improve machine handling in automatic winding and automatic assembly processes. An object of the present invention is to provide a high-strength oxide magnetic material whose core is less likely to be damaged.

[Background that led to the completion of the invention] The present invention is based on various experimental studies conducted to improve various characteristics of high-frequency ferrite core materials used in television receivers, radio receivers, etc. During the process, we learned that by adding appropriate amounts of lithium oxide and tungsten oxide to a type of ferrite base material that had been used in the past, it was possible to obtain a high-strength material that was less susceptible to core breakage. It was completed based on the obtained results.

[Means for solving the problems] The present invention, which can solve the above problems, has the following features:
It consists of two inventions, the first of which uses ferrite containing nickel, copper, and tinny as a base material, and contains 2 to 23 mol% lithium oxide and 77 to 98 mol% tungsten oxide. The second invention uses ferrite containing manganese and zinc as the base material.

Here, "high strength" means that the obtained ferrite core is difficult to break, and does not refer only to high mechanical strength itself, but also to comprehensively including its probability distribution. It is something that is evaluated. Since the ferrite core obtained in the present invention is a type of ceramic fired product, no matter how much effort is made to maintain constant manufacturing conditions and make the quality uniform, each core produced will have a considerable amount of strength. Variations are inevitable. As with the strength distribution of the obtained core, or in other words, the probability distribution of core breakage (cracking or chipping), it is said that the Weibull distribution is most suitable, as in the case of the lifespan of mechanical parts. During automatic winding or various automatic assembly processes, when a ferrite core is held and positioned by being brought into contact with a reference surface, pressure or impact force is applied to the core. In order to withstand this, it is important that not only the average strength of the core is high to some extent, but also that the probability of existence of a core with mechanical strength that can withstand the expected applied force is high. As mentioned above, the ferrite core is a fired product, and if the necessary magnetic properties are considered, it is impossible to make the average strength extremely large. Therefore, if we can manufacture a core with a strength distribution that has a sharp peak slightly larger than the expected maximum applied force, even if the average value is the same, there will be almost no core breakage during the automatic assembly process, etc. It turns out.

A factor representing the shape of this probability distribution is the so-called "Weibull coefficient (m value)." Therefore, it is desirable to use a magnetic material that has an average strength above a certain level and a large Weibull coefficient. The high-strength oxide magnetic material according to the present invention can completely satisfy these requirements.

[Specific structure of the invention] The present invention will be explained in more detail below.

As described above, the present invention uses ferrite containing nickel, copper, and zinc or ferrite containing manganese and zinc as a base material, and 2 to 23 mol% of lithium oxide and 77%
~98 mol% tungsten oxide
This is a high-strength oxide magnetic material with a composition containing ~8% by weight.

Here, the ferrite containing nickel, copper, and zinc or the ferrite containing manganese and zinc used as the base material may be any ferrite containing at least these elements at the same time, and other elements may be further added. There is no problem in this case. For example, ferrite containing nickel, copper, and zinc includes ferrite having a composition in which m- of nickel is replaced with manganese or magnesium. The reason why the ferrite used as the base material is limited to only ferrites of this type is based on experimental facts.

This is because, as will be described in detail later, in other types of ferrite, the average strength decreased and the Weibull coefficient hardly increased, or conversely, the Weibull coefficient decreased. Incidentally, for example, in the case of nickel-zinc ferrite, the Weibull coefficient increases slightly by adding the above additives, but the average strength decreases, while in the case of magnesium-zinc ferrite, the Weibull coefficient hardly changes but the average strength decreases. In the case of copper-salt ferrite, the Weibull coefficient and average strength do not change much, and no significant effect is observed.

Next, lithium oxide and tungsten oxide are used as additives. Here, the amount of lithium oxide is 2 to 23
It is also based on experimental facts that the amount of tungsten oxide is set at 77 to 98 mol%. In other words, regardless of the composition of additives of the type B, the Weibull coefficient increases by more than twice as much as when no additive is added over a wide range of about 0.5% by weight or more, but the amount of lithium oxide is 23
This is because if the amount exceeds 77 mol% (the amount of tungsten oxide is 77 mol% or less), the average strength will become considerably low even if the amount added changes. The amount of these additives added is in the range of 4 to 8% by weight based on the base material ferrite. The lower limit was set at 4% by weight because sufficient average strength would not be achieved unless at least that amount was added.
On the other hand, the reason for setting the upper limit at 8% by weight is that adding more than this will actually reduce the average strength, and this type of additive is much more expensive than the base material ferrite, so it is necessary to mix in large amounts. This is because it is not economical and also undesirable as it may deteriorate the magnetic properties.

The above addition range is such that the Weibull coefficient of the oxide magnetic material is large and a high average strength can be maintained, but more preferably 5 to 15 mol% of lithium oxide and 95% of lithium oxide are added.
Additives consisting of ~85 mol% tungsten oxide
．． It is added within the range of 5 to 7.0% by weight. In particular, when this zinc-based ferrite is used as the base material, the average strength is 1440 kg/d or more (1350 kg/d for the base material alone).
g/cIIr) and the Weibull coefficient can be set to about 10 or more (5.8 in the case of the base material alone), making it possible to extremely reduce the core failure rate. This will be clearly understood from the description of Example 1 and the drawings below.

Next, examples of the present invention will be described together with comparative examples that are not included in the scope of the present invention.

[Example 1] As the base material ferrite, iron oxide (F~03) 47.3 mol%, dumbbell oxide (ZnO) 18.4 mol%, nickel oxide (NiO) 28.8 mol%, copper oxide (Cub) 5 ．．
A powder with a blending ratio of 5 mol% was prepared, and lithium oxide (L120) was varied in the range of 0 to 50 mol%, tungsten oxide (WO,) was varied in the range of 100 to 50 mol%, and the The amount of addition to the base material ferrite was O (no addition). These samples were mixed, calcined at 750 to 850°C, and wet-pulverized with alcohol. Then, it is molded into a rectangular parallelepiped shape using a press molding machine, and is heated to 1 to 8
Fired for an hour, length 25m+a, width 511111. height 3
A rectangular parallelepiped magnetic core of +wm was obtained. Then, the bending strength of each of these samples was measured.

The measurement results are shown in the attached drawings. Figure 1 shows the composition of the additive, the amount added, and the bending strength (all units are kg/cd).
), and FIG. 2 is an explanatory diagram showing the relationship with the Weibull coefficient. In addition, the bending strength in the case of the composition of the base material ferrite alone without any additives is 135
0 kg/cd, Weibull coefficient is 5.8. As is clear from Figure 2, when 0.5% by weight or more of this type of additive is added, the Weibull coefficient becomes about 10 or more regardless of the composition ratio, which is about 2% compared to the case without additives. It is possible to increase the value to a very large value, about twice or more. Also, 2 to 23 mol% of lithium oxide and 77 to 9
When 4 to 8% by weight of an additive consisting of 8 mol% tungsten oxide is added, the bending strength is also improved, and can be increased to the same level or higher than that without the addition. Especially lithium oxide 7.5 mol%, tungsten oxide 92.5
About 1670 kg in the vicinity of mol% and addition amount of 6.5% by weight
A high bending strength of /c+/ was obtained. These values of bending strength and Weibull coefficient were very good, and it was possible to almost prevent the occurrence of core breakage during automatic winding processes and the like. As shown in Figure 3, which shows the relationship between firing temperature and Weibull coefficient, the Weibull coefficient does not change drastically even if the firing temperature is changed within a certain appropriate range; rather, it depends greatly on the presence or absence of additives. It turned out that there was.

An additional effect of adding such an additive is the relative temperature coefficient a of magnetic permeability.

You can make scales smaller. In other words, the relative temperature coefficient C1p of magnetic permeability in the case of base material ferrite alone is approximately 26
Although it is about X10-', it can be made very small to about 5 to 2X10-' by adding additives as mentioned above. This means that it is extremely effective when temperature compensation is performed by combining a ferrite core with a capacitive element in an LC resonant circuit, an electronic tuning circuit, or the like.

[Example 2] 54 mol% of iron oxide (FI203) as base material ferrite
, dumbbell oxide (ZnO) 11 mol%, manganese oxide (Mn
A powder having a blending ratio of 35 mol% O) was prepared, and additives consisting of 5 mol% lithium oxide (Li, O) and 95 mol% tungsten chloride (WO3) were added to it.
Rectangular parallelepiped magnetic cores were obtained in substantially the same manner as in Example 1 for a sample containing 5% by weight and a sample containing no additive.

The results of measuring the bending strength of this magnetic core: Without additives, the bending strength was 740 kg/(d, Weibull coefficient was 4
2, whereas the added sample had a bending strength of 95
Very large values such as 0 kg/cd and Weibull coefficient of 14 were obtained for both.

In the case of such a manganese-zinc ferrite, the same tendency as in the case of the nickel-copper-zinc ferrite described in Example 1 is observed. , 2-23 mol% lithium oxide and 7
7-98 mol% tungsten oxide and 4-811% by weight
It has been confirmed that it is effective when added. Also in the case of this example, the relative temperature coefficient αp of magnetic permeability is approximately 2.2XI
It was also confirmed that the value was O-', which was an extremely small value that was half that of the case of the base material alone.

[Comparative Example 1] Base material ferrite: iron oxide (Fe, 03) 45 mol%, zinc oxide (ZnO) 10 mol%, oxidized steel (Cub)
Using powder with a blending ratio of 45 mol%, we investigated the case where 4.5% by weight of additives consisting of 5 mol% lithium oxide and 95 mol% tungsten oxide were added to it. Breaking strength is 890kg/
ri, the Weibull coefficient was 12.1, whereas
When added as above, the bending strength is 800 kg/c
nr and Weibull coefficient were 11.6, and it was recognized that both were slightly low.

[Comparative Example 2] 45 mol% iron oxide (Fa, 03) as base material ferrite
, zinc oxide (ZnO) 10 mol%, nickel oxide (Ni
p) Use of powder with a blending ratio of 45 mol%, with 5 mol% of lithium oxide and 95 mol% of tungsten oxide.
When investigating the case of adding 4.5% by weight of additive material consisting of
/cd, Weibull coefficient was 7.8, whereas when added as above, the bending strength was 620kg/c+
J, the Weibull coefficient was 10.2, and although the Weibull coefficient was slightly higher, it was recognized that the bending strength was significantly lowered.

[Comparative Example 31 Base material) Iron oxide (Fa, O,) 45 mol% as elite
, zinc oxide (ZnO) 10 mol%, magnesium oxide (
Using powder with a blending ratio of 45 mol% (MgO), we investigated the case where 4.5% by weight of additives consisting of 5 mol% lithium oxide and 95 mol% tungsten oxide were added to it. The bending strength is 1240k
g/c++r, the Weibull coefficient was 101, whereas when added as above, the bending strength was 640 kg.
/cIIF, the Weibull coefficient was 10, and as in the case of Comparative Example 3, it was observed that the bending strength was extremely reduced.

[Effects of the Invention] Since the present invention is an oxide magnetic material configured as described above, it is possible to increase the bending strength of the ferrite core and its Weibull coefficient. Even if considerable pressure or impact force is applied during the process, the core is less likely to crack or chip, making it easier to introduce automatic assembly equipment, improving yields, and significantly increasing manufacturing efficiency.
It is extremely effective in various fields such as resonant circuits and electronic tuning circuits, especially in electronic circuits that require temperature compensation, and it has many advantages such as being able to be manufactured at a low cost like the ferrite core that has been used in the past. It is possible to have a certain effect.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram plotting the composition and amount of flexural strength when additives consisting of lithium oxide and tungsten oxide are added to the nickel-copper-zinc ferrite according to the present invention, and Figure 2 is a similar diagram. FIG. 3 is an explanatory diagram in which the Weibull coefficient is plotted against the composition and amount of additive material added, and FIG. 3 is an explanatory diagram showing the relationship between the firing temperature and the Weibull coefficient. Patent applicant Fuji Electrochemical Co., Ltd. Agent Shigeru Estimate

Claims (1)

[Claims] 1. For ferrite containing nickel, copper, and zinc,
A high-strength oxide magnetic material characterized in that 4 to 8% by weight of additives containing 2 to 23 mol% of lithium oxide and 77 to 98 mol% of tungsten oxide are added. 2. For ferrite containing manganese and zinc, 2-
A high-strength oxide magnetic material characterized in that 4 to 8% by weight of additives containing 23 mol% lithium oxide and 77 to 98 mol% tungsten oxide are added.