JPS6076107A - Magnetic core based on lithium-zinc-manganese ferrite and method of producing same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic core of an oxide ferromagnetic material made of spinel structure ferrite having a cubic structure, and its Ij@
! Regarding the manufacturing method.

Consisting of spinel ferrite having a cubic crystal structure,
Oxide ferromagnetic cores are used in large numbers in induction coils in the fields of telecommunications and industrial and consumer electronics, and in transformers. Depending on the application, the material in question can be divided into four types.

The first type is a low loss ferrite intended for high quality coils used in filters. The magnetic core is usually a circular or square shaped core.

- The second cedar has high initial permeability and is for low power broadband and pulse transformers. Magnetic cores are usually annular, E-cores, and round cores of various shapes.

- The eighth form is for high power applications, e.g. lO~100KH
Suitable for power transformers operating in the 2 frequency range. The range of processing vehicle power is typically 10-750W. The magnetic core is usually a U-core or an E-core.

A fourth type is intended for use in high quality coil cores used in the frequency range of 2 to 12 Mn2. The magnetic core is usually a shaped core, ring, ball or bead.

Other applications outside of the upper filtration are as magnetic cores used in antenna ballasts, noise inverters, and particle accelerators. The memory core is
Not typically included.

Ni-Zn ferrite has hitherto been considered for applications at high frequencies (particularly above l MHz) due to its high resistance (
ρ=105Ω·crn) and was used as a magnetic core material. (Vine materials used at frequencies above I MHz are, of course, also suitable for applications at frequencies below M I MHz.) Due to the high cost of Ni-Z'n ferrites, there are no substitutes with comparable electrical and magnetic properties. Efforts were made to explore the ferrite type.

The present invention provides such a ferrite system. It has the following composition, and the values of 2・a+x+y・δ and ε are each 0.05 <Z < 0. '+5 U <a <0.05 0-01 <, X+V<0. I, 85 < δ, 15, 5X < 6 < +0.2 ra, and the composition includes L mass % Bi as a sintering agent,
08 and! Add % ■, 06 to L nail, and add p and q.

This material is based on a special b-sat-zn-)4n ferrite, characterized in that the values of In addition to the approximately 80% cost savings of using ferritic cores, an important advantage is that the sintering temperature can be lowered by reducing the
By adding O8 and/or v, o, N1-Zn
The sintering temperature is lower than that of 7-elite, and since the addition of forging is extremely small, it does not have a negative effect on the electrical and magnetic properties, and as a result, this Li-Zn
In the -In ferritic system, it is possible to produce materials that are dense and bond together in small particles, thereby leading to high mechanical stiffness. In some cases, Ni with comparable electrical and magnetic properties
A fracture strength five times greater than -Zn ferrite was measured.

The amount of added sintering agent, on the one hand, should not exceed 1.2% by weight, since using a larger amount will have a negative impact on the magnetic and magnetic properties. It is. On the other hand, the reason for this is that if a cypress smaller than this is used, the sintering temperature will not be lowered sufficiently, and as a result, the material to be sintered will Reactions occur with the furnace material, evaporation of Li occurs, and the particles become larger, all at the expense of - gaseous, magnetic and mechanical properties.

Another advantage of lowering the sintering temperature is that this Li-Zn-M
1 crazy resistance of n ferrite, but otherwise comparable Ni
-The electrical resistance is higher than that of Zn 7 elite.

Although it is a small amount, In of the specific snoring, Bi as a sintering agent,
The presence, in combination with o8 and V,05, proved essential for obtaining high electrical resistance and low losses comparable to those of Ni-Zn ferrite.

Depending on the value of Zn s Fe, Bi2O2 and v,06, the range must be varied within the range of 0.01 to 0.25 formula units.

Furthermore, an advantage of the Li--Zn--Mn ferritic system is that it offers a large number of materials meeting different specifications, especially by varying the Li-''Zn ratio.

With a zinc content in the range of 0.85 to 0.45 formula units, a material with a magnetic permeability of 250 can be obtained.

A zinc-containing maximum in the range of 0.25 to 0.85 formula units yields a material with a magnetic permeability of 120, which can be used up to higher frequencies.

With a zinc content in the range of formula units from 0.15 to 0.25, a material with a magnetic permeability of 60 can be obtained,
This is useful up to even higher frequencies. At most 0
．． By adding 0OI7) of the 05 formula unit, a material with even lower loss can be obtained, and the temperature coefficient of magnetic permeability can also be controlled by the COS content.

This series of materials can be used up to the highest frequencies.
Characterized by a zinc-containing Mk within the range of 10 to 0.20 formula units. This results in a permeability that is too low for low zinc contents, especially below 0.05 formula units. Zni
The upper limit of the view is determined by the desired Curie temperature.

A number of examples of this invention will be explained in more detail with reference to the drawings.

Example 1 Llo, 80znO, 40Mn1+, 08Fe2.02
0B, 8?1 (0.46 weight% Bi, 08 and 0.2
8fold S% v, 0. with) r made: 617.5 to 9 (DFeO26, J19 In
028' No. 8 1 121-5 kg (D ZnO1t, s 7 kg (
7) V, O,,3,77 kg of B12O3 and 88.
1 kg of L1□008 was weighed and ground with 600 liters of water in a ball mill with a capacity of 2000 liters for 4 hours. The powder-water mixture was spray dried and the resulting granulate was precalcined at 850° C. in a rotary tube furnace.

800kg pre-fired #1. The material was ground with 500 liters of water in a ball mill with a volume of 2000 liters for 6 hours, then each fi71, ao
Rinsed twice with liters of water and 41 liters of dispersant.

Some binder, such as an aqueous emulsion of polymethacrylate, was added to the mixture. The concentration of the binder is dry powder I powder 1
1 g of solid binder per 00 g. The mixture was then spray dried. Ring (φ, /φ. = 9715 mm
) was compressed at a pressure of l t/cWL" and then sintered in a furnace: in air at a peak temperature of 1025° for 2 hours. The properties of the sintered ring are: specific density,
(5 specific aensi, ty) d =
4.759/Cm8, magnetic permeability 1μm248; magnetic loss < tgδ/μhMHz -5ox 1 o- and (
1, δ/μ8M to 2-260
During 70℃, fractal index ρ-0-8X 1 o6Ωm0 composition 0.80 ZnO, 4゜MnX Fe2.8O-X
-1-yo4+! Two series of many magnetic cores with M are Mn
and Zn-content 'f in the above manner (therefore o
, 4 ctmj 1% Bi2O3 and 0.28 lucid% v
20. tJA was prepared by adding ).

All the magnetic cores in the series have magnetic receptivity μi of 200 (for this purpose, they are made smaller than in example 1 by about 50
sintered at a lower temperature), the magnetic cores of the second series were all 2
50 μm (for this purpose they were sintered at a temperature of about 15 Q °C higher than in Example 1).The loss coefficient stars of the magnetic cores thus produced were measured.
The results of measurements on a series of magnetic μ cores are recorded in FIG. 1 (measurements at 11 MHz) and FIG. 2 (measurements at 5 MHz) as a function of Mn and Fe content. Lines connecting points with equal loss coefficients indicate so-called iso-area, loss. L-0 in both graphs indicates the stoichiometric Fe content.

A negative V f+α indicates a deficiency of Fe, and a positive L value indicates a
Indicates an excess of e. From Figures 1 and 2, the lowest loss is F
It can be seen that this can be seen in a magnetic core that is slightly lacking in e. Depending on the frequency range, the In- content of the core must be slightly lower (at a frequency of I MHz) or slightly higher (at a frequency of 5 MHz) to obtain a minimum value of the loss factor. It was carved into a monument.

In a similar manner, FIG. 8 (measurement at 1 MHz) and FIG. 4 (measurement at 5 MHz) show the results of loss measurements in the second series of cores.

Furthermore, it can be seen from this that a slight deficiency of Fe is optimal in terms of loss G. However, to obtain the minimum value of the loss factor, at the frequency of ] MH2, In
- The content should preferably be low, 5 MH
It was found that at the frequency of z it had to be slightly higher.

FIG. 5 shows the measured resistance of the first series of magnetic cores, and FIG. 6 shows the measured resistance of the second series of magnetic cores as a function of Mn and Fe contents. In both cases,
The highest resistance value (107 Ωm) is found in the core slightly deficient in Fe.

Example 2 “0J8znO,20000,08Mn0.04Feg
, 1608.78 (064 weight II%) v905 and 0.
2i1 (jll1% + 7) Bi, made by N1ili with 08: first milled, spray dried and precalcined as in Example 1, then 5ooII precalcined granulate with 600g water for 6 hours; Milled in a 2 liter ball mill. Then the mixture was heated to 2o.

It was evaporated to dryness at 0.degree. C. and compacted into rings, which were sintered as in Example 1. The sintering temperature in this case was 965° C. in order to obtain blister pellets that allow low losses. The properties of the sintered ring are as follows: -4.589/c
m81, μ1=60, gδ/μ)□. MHz=76X
10 and (tδ/μ)40MH2” 220 x1O
-6, p = 0.2 X l O'Ωm and human TF -
20X l O-'.

The above properties make the material in question eminently suitable for use as core material in coils operated at higher frequencies. The minimum value of the loss factor is obtained by adjusting the correct Fe-containing piece.

This becomes clear from FIGS. 7 and 8.

Figure 7 shows the v
Figure 2 shows the loss at 10 MHz of a number of magnetic cores with the production of 206 and 0.2% Bi, with the addition of o8. All cores were sintered to have μ, −60.

The lowest value is found in a core with a He deficiency of slightly less than 0.20. Figure 8 shows the losses measured at 40 MHz. The lowest losses are found in cores with a Fe deficiency of about 0.2.

The maximum deviation from the chemical Fe tolerance, indicated by δ゛, is
It can be between -0.85 (deficiency of Fe) and +0.15 (excess of li'e). Therefore, the value of δ is -〇,
aa<δ(+0.15°I)) Based on the above,・
A deficiency in Fe is preferred. That is, -0,85 (δ<-0·05 CO@Scenic is important for the temperature coefficient of permeability, which is as constant as possible. This is shown in Figure 9. This figure shows that the 00-containing Change the position (always 0.2 Hqb 17.
) 131sOa and 0.4 heavy J? t%(7)V, O5
7JI], tT manufactured composition "o, s 84 "o,
ga -a Ooa MnO, 04”2.s 44+1
show. The magnetic cores were sintered at a temperature such that they all had μ soil-60. The curve is a temperature range of 5 to 25 degrees Celsius, connecting points with a constant temperature coefficient, and the curve is 25 to 75 degrees Celsius.
In the temperature range I, connect the points with a constant temperature coefficient. 00 content view -0,027 (further corresponding to the intersection of the curve view and the mutual), a temperature coefficient that is constant from 5 to 75°C is obtained.

This is compatible with a ferrite core with a given Fe@wrought (Δ=-0,1). Greater Fe deficiency (Δ
In the composition with (3,2), point p moves to the right. Therefore, the COS yield required to obtain a constant TF between 5 and 75°C increases. (The maximum required 00 content is about 0.05.) When the Fe deficiency becomes large, the curves and rays will occupy a lower position. Therefore, the TF value becomes even smaller.

It is noteworthy that CO becomes trivalent in an oxidizing medium. In order to obtain useful materials, one should ensure that sintering is carried out in an environment where at most half of the CO ions are trivalent. This means that in the formula describing the composition of this ferrite material for magnetic cores, the upper limit of ε is equal to -1-045a.

The lower limit of ε is determined by the condition that Mn becomes completely divalent at higher temperatures or in less oxidizing media. To explain this, when ε>u, 5x0 and the addition of sintering agent is 0.8 to 0.7% by weight, the optimal
It has been experimentally confirmed that it is possible to obtain materials with a combination of properties, on the other hand, Bi,08 and V,O.

It has been determined that adding both is most advantageous. In particular, 0.2 wt.% Bi, .o8 and 0.4 wt.% v.0. Advantageous results were obtained when adding

However, since the optimum combination of properties is not required for all applications, in some cases Bi, 08 alone or V205 alone can be added to reduce the sintering temperature.

[Brief explanation of drawings]

Figure 1 shows a large number of Li-zn-Mn with the same magnetic permeability (μm200) but different In and Zn content.
This is a graph showing the "equal loss" of a ferrite core, where the loss was measured at I MHz. Figure 2 is the same graph as Figure 1, but the loss was measured at 6 Mn2. 8M is the same graph as Figure 1, but
This is a graph in which loss was measured with a core having a magnetic permeability of 250. Figure 4 is the same graph as Figure 2, but the loss is 250
Figure 5 shows a number of LiZnMn7 cores with the same permeability (μm20(1)) but with different Mn and Zn containing scraps.
This is a graph showing the so-called "equal resistance" of a x5ite core. Figure 6 is the same graph as Figure 5, but the measurement was performed with a core having a magnetic permeability of 250. FIG. 8 is a graph showing a large number of LiZnMn0O-ferrite cores; FIG. 9 is a graph showing a large number of LiZnMnC with μ=60. 1 is a graph showing the temperature coefficient TF of magnetic permeability of a ferrite core as a function of Co-containing soil. CfuU-CfuL Σ CtsuChu-,1 Cfu1U] Hifu-hifu () 1 Continuation of 1st page Priority claim 01 Cocoon July 6th [Phase] Netherlands (NL) [
Stock] 8402146 @ Inventor Benardas Huberta Netherlands 5621 Bass Johannes Henke
Inventor Cornelis Jacob Netherlands 56
21 Bass Nisverbut Vautzweczach 1 A Isodofuen Fluhneer Isodofuen Fluhne

Claims (1)

[Claims] t In a magnetic core of an oxide ferromagnetic material made of spinel ferrite having a cubic structure, the ferrite has the following composition: and the values of zta, x+Y*δ and ξ are respectively U, 05 RiZ < 0.45 U < a < U-05 +J・(+1 < X+y < 0.25-0.85 <
δ<+U, ta -0.5
Add v205 of 08 and Yu11, and p・q and p+q
A magnetic core based on lithium-zinc-manganese ferrite, characterized in that the values of are in the range 0 <: p < 1.2 0 < q < 1-2 0.2 < p + q < 1.2. The value of a p+q is '-8 < 1) + q < o, '7 li! The magnetic core according to claim 1 in h. 8. The magnetic core according to claim 1 or 2, wherein the values of p and q are in the ranges of p>0 and q>0, respectively. 4 The value of z is 0.85<Z<U. 45. The magnetic core according to claim 1, which is within the range of 45. 5 The values of z and a are each 0.25 (Z <0.8
The magnetic core according to item 1, wherein g is in the range 5 and a>O. 6 The values of z and a are each 11. J 5 <Z(04
5 and a>0; U) 1. The magnetic core according to item 1. 7, the f angles of z and a are each 0.10 (Z< 0.2
1J and the range 11Jt where a>0. The magnetic core according to claim 1. & In the magnetic core of an oxide ferromagnetic material made of spinel structure ferrite having a cubic crystal structure, the ferrite has the following composition, and the values of 2・a + X + yIδ and 6 are each 0.05 <Z < 0.45 o <a <0.05 0.01 <X+y<IJ-25 -O, a5<δ<+0.15 -0-6X < ε <-+-0-25a, Egaki% B12o and Hayabusa Tan% v206 were added as sintering agents, and the f angles of plq and plq were each 11 (p (1・2 o<qt・2 0・2 <plq< To produce a magnetic core based on lithium-zinc-manganese ferrite in the range 11 of 1-,2, a homogeneous powder mixture is prepared and compressed to form the magnetic core at a temperature in the range of 950 to 100°C. 1. A method for producing a magnetic core based on lithium-zinc-manganese 7-elite, characterized in that it is sintered by heat treatment.