CN101531504B - Wave absorber - Google Patents

Abstract

The present invention provides a wave absorber. Due to the wave absorber containing a MnZn series ferrite cemented body has a composition as follows, it is capable of reducing manufacture cost greatly, having an excellent curie temperature, matching thickness, temperature characteristic and frequency characteristic of the wave absorber characteristics, and improving an anti-chopping characteristic obviously. The wave absorber contains the following main components: 45.0-49.0 mol percent of ferric oxide by Fe2O3, 19.0-23.0 mol percent of zinc oxide by ZnO, and 28.0-36.0 mol percent of manganese oxide by MnO; in addition, the wave absorber also contains accessory constituent of cobalt oxide, silicon oxide, vanadium oxide, calcium oxide and niobite oxide with certain quantity separately.

Description

Wave absorber

Technical field

The present invention relates to the wave absorber that constitutes by the MnZn series ferrite material, do not contain Ni in the principal constituent of said MnZn series ferrite material; The invention still further relates to the wave absorber that in anechoic chamber, or electric wave absorbing barrier etc., uses.

Background technology

In recent years, be accompanied by the development of ICT and popularizing of various electronic machines, unwanted electromagnetism noise becomes problem to the influence that the precision instrument relative unit brings.

When measuring said electromagnetism noise, need the not anechoic chamber, of reflection electromagnetic wave (hertzian wave anechoic chamber), and in the interior wall of anechoic chamber,, used wave absorber.

In addition, for the electric wave that prevents television set is produced the obstacle that signal receives by reflection such as high-rise, in the exterior wall of buildings, used wave absorber.

Because such wave absorber quilt uses in a large number in the inside of anechoic chamber, or exterior wall etc., therefore require the product cost of reduction wave absorber.

As existing wave absorber; For example; As having the wave absorber that return loss is the characteristic more than the 20dB at 40MHz～450MHz frequency band, comprise the wave absorber that makes magnesium-Zn ferrite sintering and obtain, making nickel-Zn ferrite sintering and wave absorber of obtaining, manganese-nickel-copper-Zn ferrite etc.

In the middle of these, though magnesium-Zn ferrite material raw materials cost is more cheap, the matching thickness of wave absorber up to 8mm about, the gross weight of the wave absorber that uses in the exterior wall for interior wall that reduces anechoic chamber, or buildings etc. has restriction.

On the other hand, though we can say and contain the starting material that nickel is the wave absorber characteristic that helps obtaining to expect as the ferrite of principal constituent, its cost uprises, and not meeting of the present invention is the aim of target to reduce cost.In addition, in the anechoic chamber, of the electromagnetism noise of measuring the precision instrument relative unit, the frequency band of estimating the electromagnetism noise is by stdn, and requiring the return loss in 30～1000MHz scope is more than the 20dB.

On the basis of such actual state, the application contriver has proposed an invention that Mn-Zn is a wave absorber, and its application number is willing to 2007-272587 number application (is on October 19th, 2007 in the applying date of Japan) for Japan is special.Based on this motion, the characteristic that requires can be remained on the high-caliber basis and seek to reduce manufacturing cost.

But, wave absorber to be processed ceramic tile (tile) shape, and be arranged under the extraneous adornment or the situation in the interior finish of structure, shape, the specification that must meet structure wait processes.For example, when being used for the exterior wall in building,, then between the wave absorber panel, produce the slit, perhaps can not be arranged on the determined design attitude if be not processed into the dimensional precision of regulation.If use wave absorber in the past to process in order to address the above problem; Because a little less than its anti-physical shock; Adding man-hour or the time in most cases can produce damaged, crackle, reducing, become and cause expensive problems such as major cause thereby can produce yield rate in construction.

The present invention is the invention of founding in order to solve above-mentioned problem basically, as the prior art relevant with the application, can enumerate No. 3278373 communique of Japanese Patent, TOHKEMY 2001-53483 communique, TOHKEMY 2005-213115 communique.

No. 3278373 disclosed technology of communique of Japanese Patent is: in the NiCuZn based ferrite, add the MoO as minor component ₃Improve anti-cutting property.

In addition, the disclosed technology of TOHKEMY 2001-53483 communique is: in the NiCuZn based ferrite, add the V as minor component ₂O ₃Improve anti-cutting property.

In addition; The disclosed technology of TOHKEMY 2005-213115 communique is: in the NiCuZn based ferrite, suitably selected and interpolation improves anti-cutting property etc. as the oxide compound of the W of minor component, the oxide compound of Mo, the oxide compound of Bi, the oxide compound of Pb, the oxide compound of Mg, the oxide compound of Si, the oxide compound of V and the oxide compound of Nb.

But these prior aries all are the technology relevant with the NiCuZn based ferrite, with the present invention on principal constituent is formed, be diverse.In addition, these prior aries and the present invention the formation and the addition of composition of the minor component that will add also all inequality.

The present invention is exactly the invention of on the basis of such actual state, founding; Its purpose is to provide a kind of wave absorber of Mn-Zn based ferrite; Said wave absorber can seek to reduce manufacturing cost in that the characteristic that requires is remained on the high-caliber basis; Thus, can improve anti-the cutting property of cheap Mn-Zn based ferrite.

Summary of the invention

In order to address the above problem, the present invention provides a kind of wave absorber of the MnZn of comprising based ferrite sintered compact, and this wave absorber contains following principal constituent:

Be converted into Fe ₂O ₃Be 45.0～49.0 moles of % red stone,

Be converted into zinc oxide that ZnO is 19.0～23.0 moles of % and

Be converted into MnO and be 28.0～36.0% manganese oxide,

In addition, with respect to 100 weight part principal constituents, also contain following minor component:

Be converted into powder blue that CoO is 1000～7000 ppm by weight, be converted into SiO ₂Be 10～200 ppm by weight silicon oxide, be converted into V ₂O ₅Be 50～1000 ppm by weight vanadium oxide, to be converted into CaO be the quicklime of 200～2500 ppm by weight and be converted into Nb ₂O ₅It is the niobium oxides of 50～500 ppm by weight.

In addition, as the preferred mode of wave absorber of the present invention, it is 3500～6500 ppm by weight that wherein above-mentioned powder blue is converted into CoO.

In addition, as the preferred mode of wave absorber of the present invention, wave absorber has property: Tc is more than 80 ℃; Sintered density is higher than 4.7 (g/cm ³); The value of the real component ε ' of the complex permittivity under frequency 30MHz satisfies the condition of 10＜ε '＜30; The value of the real component μ ' of the complex magnetic permeability under frequency 30MHz satisfies the condition of μ '＜80; The imaginary component μ of the complex magnetic permeability under frequency 30MHz " value satisfy μ "＞260 condition; Matching thickness is below the 6mm; Return loss under 25 ℃ is more than the 20dB; And the La Tuola value is below 0.5%.

In addition, as the preferred mode of wave absorber of the present invention, this wave absorber be shaped as tabular ceramic tile shape.

Embodiment

Below, specific embodiments of the invention describes.

(constituting the explanation of the principal constituent of wave absorber of the present invention)

Wave absorber of the present invention contains the principal constituent that comprises red stone, zinc oxide and manganese oxide and constitutes.Wherein contain and be converted into Fe ₂O ₃Be 45.0～49.0 moles of % (being preferably 46.0～48.0 moles of %) red stone, contain that to be converted into ZnO be the zinc oxide of 19.0～23.0 moles of % (being preferably 20.5～22.5 moles of %) and contain and be converted into the manganese oxide that MnO is 28.0～34.5 moles of %.

In the compositing area beyond the above-mentioned scope; The necessary complex phase of electric wave absorption characteristic can not satisfy the frequency response characteristic of specific inductivity frequency response characteristic, the complex phase of permeance; Perhaps the matching thickness of wave absorber perhaps can not obtain the suitable Curie temperature as wave absorber greater than 6.0mm.

Here said electric wave absorption characteristic is by following formula (1) expression, if the frequency gets higher that the real component μ ' of complex magnetic permeability is reduced then causes obtaining the good electric wave absorption characteristic from low-frequency band.In addition, at the imaginary component μ of complex magnetic permeability " under the low situation, can cause the increase of matching thickness.

In addition, if the real component ε ' of complex permittivity is not suitable value, then cause the reduction of return loss.

Formula (1)

Volume reflection (dB) $\mathrm{Ref}=20\mathrm{Log}\left|\mathrm{\Γ}\right|=20\mathrm{Log}\left|\frac{Z_{\mathrm{In}}-1}{Z_{\mathrm{In}}+1}\right|$

$Z_{\mathrm{in}}=\sqrt{\frac{{\mathrm{\μ}}_r}{{\mathrm{\ϵ}}_r}}\tanh \left(j\frac{2\mathrm{\πd}}{{\mathrm{\λ}}_0}\sqrt{{\mathrm{\ϵ}}_r{\mathrm{\μ}}_r}\right)$

μ _r＝μ′ _r-jμ″ _r ε _r＝ε′ _r-jε″ _r ${\mathrm{\λ}}_0=\frac{C}{f}$

The d=matching thickness

In addition, under the obviously low situation of Curie temperature, the temperature of wave absorber itself is higher than Curie temperature because of the heat of conversion easily, forfeiture magnetic, thus produce as the such unfavorable condition of the afunction of wave absorber.

When the content of above-mentioned red stone is lower than 45.0 moles of %, can produce following unfavorable condition: owing to the imaginary component μ of complex phase to permeance " reduction to make matching thickness be more than the 6mm, and Tc becomes below 80 ℃.In addition, when the content of above-mentioned red stone during greater than 49.0 moles of %, can produce following unfavorable condition: the frequency gets higher that complex phase is reduced the real component μ ' of permeance, at the low frequency region of 30MHz, the return loss under room temperature (25 ℃) is below the 20dB.

In addition; When the content of above-mentioned zinc oxide is lower than 19.0 moles of %; Can produce following unfavorable condition: make the frequency gets higher of complex phase to the real component μ ' reduction of permeance, at the low frequency region of 30MHz, the return loss under room temperature (25 ℃) becomes below the 20dB.In addition,, can produce following unfavorable condition: owing to the imaginary component μ of complex phase to permeance when the content of above-mentioned zinc oxide during greater than 23.0 moles of % " reduction to make matching thickness be more than the 6mm, and Tc becomes below 80 ℃.

(adding the explanation of the minor component in the principal constituent to)

(1) as the interpolation of the powder blue of minor component

With respect to principal constituent 100 weight parts of above-mentioned MnZn based ferrite, it is 1000～7000 ppm by weight that the powder blue as minor component that contains is converted into CoO, is preferably 3500～6500 ppm by weight.

Add an amount of cobalt and can bring the effect that complex phase is shifted to lower frequency side the decay of the real component μ ' of permeance, when the content of above-mentioned powder blue is lower than 1000 ppm by weight, make the frequency gets higher of complex phase the real component μ ' reduction of permeance.Its result, have the trend that produces following unfavorable condition: at the low frequency region of 30MHz, the return loss under room temperature (25 ℃) is below the 20dB, and the return loss under negative 20 ℃ (20 ℃) is below the 15dB.

In addition; When the content of powder blue is higher than 7000 ppm by weight; On the contrary, there is the trend that produces following unfavorable condition: make the frequency gets higher of complex phase, at the low frequency region of 30MHz to the real component μ ' reduction of permeance; Return loss under room temperature (25 ℃) is below the 20dB, and the return loss under negative 20 ℃ (20 ℃) is below the 15dB.

In addition, the powder blue of 1000～7000 ppm by weight adds the interaction of adding vanadium oxide, quicklime and niobium oxides, produces the synergy of anti-cutting property.

(2) as the silicon oxide (SiO of minor component ₂) interpolation

With respect to principal constituent 100 weight parts of above-mentioned MnZn based ferrite, the silicon oxide as minor component that contains is converted into SiO ₂Be 10～200 ppm by weight, be preferably 30～150 ppm by weight.When the content of silicon oxide is lower than 10 ppm by weight, produce unfavorable conditions such as the obvious reduction of sintered density.In addition, when the content of silicon oxide is higher than 200 ppm by weight, produce the unfavorable condition that unusual particle growth occurs.

(3) as the vanadium oxide (V of minor component ₂O ₅) interpolation

With respect to principal constituent 100 weight parts of above-mentioned MnZn based ferrite, the vanadium oxide as minor component that contains is converted into V ₂O ₅Be 50～1000 ppm by weight, be preferably 100～500 ppm by weight.When the content of silicon oxide is lower than 50 ppm by weight, produce the unfavorable condition that the La Tuola value increases.

In addition, when the content of vanadium oxide is higher than 1000 ppm by weight, make the frequency gets higher of complex phase to the real component μ ' reduction of permeance, at the low frequency region of 30MHz, the return loss under room temperature (25 ℃) is below the 20dB.Matching thickness is thickening also.

In addition, the vanadium oxide that adds 50～1000 ppm by weight adds the interaction of adding powder blue, quicklime and niobium oxides, produces the synergy of anti-cutting property.

(4) as the interpolation of the quicklime (CaO) of minor component

With respect to principal constituent 100 weight parts of above-mentioned MnZn based ferrite, it is 200～3000 ppm by weight that the quicklime as minor component that contains is converted into CaO, is preferably 500～1500 ppm by weight.When the content of quicklime is lower than 200 ppm by weight; Can produce following unfavorable condition: at the complex phase of 30MHz the real component μ ' of permeance is become big (complex phase moves to high frequency side the decay of the real component μ ' of permeance), thereby can not obtain the above return loss of 20dB.

In addition, when the content of quicklime is higher than 3000 ppm by weight, can produce following unfavorable condition: under 30MHz, complex phase is to the imaginary component μ of permeance " diminish, matching thickness is thickening also.

In addition, the quicklime that adds 200～3000 ppm by weight adds and adds vanadium oxide, powder blue and niobium oxides, produces the synergy of anti-cutting property.

(5) as the niobium oxides (Nb of minor component ₂O ₅) interpolation

With respect to principal constituent 100 weight parts of above-mentioned MnZn based ferrite, the niobium oxides as minor component that contains is converted into Nb ₂O ₅Be 50～500 ppm by weight, be preferably 100～400 ppm by weight.When the content of niobium oxides is lower than 50 ppm by weight, with the unfavorable condition of the effect reduction that produces anti-cutting property raising.In addition; When the content of niobium oxides is higher than 500 ppm by weight; Have the trend that produces following unfavorable condition: the complex phase under 30MHz becomes big (complex phase moves to high frequency side the decay of the real component μ ' of permeance) to the real component μ ' of permeance, thereby can not obtain the above return loss of 20dB.

In addition, the niobium oxides that adds 50～500 ppm by weight adds and adds vanadium oxide, powder blue and quicklime, produces the synergy of anti-cutting property.

(6) other minor components

As other minor components, can contain SnO in the scope of the action effect that does not break away from the application's invention ₂, TiO ₂, NiO, Ta ₂O ₅, ZrO ₂, HfO ₂, GeO ₂, MoO ₃, WO ₃, Bi ₂O ₃, In ₂O ₃, Cr ₂O ₃, Al ₂O ₃Etc. various minor components.

Aforesaid wave absorber of the present invention can be through following method manufacturing; Promptly; The MnZn series ferrite material that consists of in the above-mentioned scope that fits in behind the sintering is shaped to for example tabular ceramic tile shape, then the sintering temperature about 1100 ℃～1350 ℃.Method of manufacture more specifically can be with reference to the experimental example among the embodiment of following record.Need to prove, as the size of ceramic tile shape, can enumerate longitudinal size and be about 50～200mm, lateral dimension is about 50～200mm, gauge is the plate object about 3～10mm.

Embodiment

Below, enumerate concrete embodiment, illustrate in greater detail the present invention.

Each material composition of weighing made the composition shown in the below table 1 that consists of behind the sintering, with iron and steel system ball mill wet mixing 16 hours.

Then, with this mixed powder in atmosphere in 900 ℃ of pre-burnings 2 hours.In the pre-burning thing that obtains, add minor component, make the composition shown in the below table 1 that consists of after burning till, with iron and steel system ball mill case of wet attrition 16 hours.

In the MnZn based ferrite powder that obtains like this, add the polyvinyl alcohol water solution of 10 weight % and carry out granulation, with 1 ton/cm ²Pressure forming for carrying out the shape of regulation of following wave absorber characteristic test.

Forming composition to such formation is burnt till.Firing condition is following: firing temperature is set at 1300 ℃ (all being in air up to 1300 ℃), in cooled region thereafter, is cooled to 1000 ℃ and control oxygen partial pressure, is carrying out nitrogen (N below 1000 ℃ again ₂) burning till under the atmosphere.

For the sample of the wave absorber of such acquisition,, measure respectively: (1) Curie temperature according to main points described below; (2) matching thickness of wave absorber; (3) return loss under frequency 30MHz, 25 ℃; (4) complex phase is to the real component μ ' of permeance, the complex phase imaginary component μ to permeance ", the value of the real component ε ' of complex permittivity (all under 25 ℃, frequency 30MHz, measuring); (5) sintered density ρ (g/cm ³); (6) La Tuola value.

(1) measuring method of Curie temperature (Tc)

Test portion is put in the heat zone, kept fully stable at each temperature, use the LCR time meter to measure the temperature profile of initial stage magnetic permeability mu i then up to temperature.Surpassing the peaked sloping portion of initial stage permeance, the point with peaked 80% is connected with 20% point, obtains the crossing point of line of its extended line and μ i=1, with it as Tc Tc.In addition, measuring frequency is 1kHz.

Need to prove that the target value of Tc Tc is more than 80 ℃.

(2) matching thickness of wave absorber (d)

The electric wave absorption characteristic of wave absorber is to use the sample of the annular shape that is processed to external diameter 19.8mm, internal diameter 8.6mm, utilizes network analyser to measure reflection coefficient with the state that is inserted in the coaxial valve.Calculate the normalized impedance of return loss and wave absorber front by the mensuration result who obtains.

The relation of normalized impedance (Z) and reflection coefficient (S) is following.

Z＝(1+S)/(1-S)

S＝(Z-1)/(Z+1)

S=(S _Sample/ S _Metal)

-20log|S|＝dB

The mark of each thickness is transformed impedance maps into Smith chart, obtain thickness through the Smith chart center through calculating, with this thickness as matching thickness (d).

Need to prove that the target value of matching thickness (d) is below the 6mm.

(3) return loss (RD under frequency 30MHz, 25 ℃ ₂₅ )

The ring of the matching thickness that the actual fabrication aforementioned calculation obtains is determined at the return loss (RD under the frequency 30MHz, 25 ℃ according to above-mentioned coaxial valve method ₂₅).RD ₂₅Target value be more than the 20dB.

(4) complex phase is to the real component μ ' of permeance, the complex phase imaginary component μ to permeance ", the value of the real component ε ' of complex permittivity (all under 25 ℃, frequency 30MHz, measuring)

Based on the method for above-mentioned (2), use the sample of the annular shape that is processed to external diameter 19.8mm, internal diameter 8.6mm, utilize network analyser to measure reflection coefficient with the state that is inserted in the coaxial valve, derive μ ', μ by the mensuration result who obtains " and ε '.

Need to prove that the target value of ε ' is the scope of 10＜ε '＜30;

The target value of μ ' is μ '＜80;

μ " target value be μ "＞260.

(5) sintered density ρ (g/cm ³ )

Measure according to Archimedes's method.

Need to prove that the target value of sintered density ρ is for being higher than 4.7 (g/cm ³).

(6) La Tuola value (Rattler Value)

The sintered compact test portion is processed into the cylindric of diameter 20mm, height 15mm, the sintered compact test portion after the processing is carried out the La Tuola test, obtain the La Tuola value.

The La Tuola test is carried out according to following main points.

At first, the weight (W1) of employed 3 the sintered compact test portions of determination test before test.Then, 3 sintered compact test portions are put in the tube (La Tuola trier) that inside has the about 10cm of diameter that stops rod (evil spirit rod), under rotating speed 100rpm, 5 minutes condition of rotational time in tube with 3 sintered compacies pulverizing.Then, measure the weight (W2) of 3 sintered compact test portions after off-test.Obtain 3 sintered compact test portions the experiment before and after the weight decrement, with it as the La Tuola value.That is, the La Tuola value is calculated through following formula (1).

La Tuola value (%)=100 * (W1-W2)/W1 ... formula (1)

The target value of La Tuola value of the present invention is below 0.5%.

The mensuration result of said projects is shown in below table 1.

One of table 1 ()

Table 2 (two: continuous)

But effect by above experimental result knowledge capital invention.That is, the wave absorber of the MnZn of comprising based ferrite sintered compact of the present invention is owing to have a following formation, therefore can seek to reduce manufacturing cost on the high-caliber basis in that the characteristic that requires is remained on, and can improve anti-cutting property.Constituting of said wave absorber contained following principal constituent: be converted into Fe ₂O ₃Be 45.0～49.0 moles of % red stone, to be converted into ZnO be the zinc oxide of 19.0～23.0 moles of % and to be converted into MnO be 28.0～36.0% manganese oxide; In addition; With respect to the above-mentioned principal constituent of 100 weight parts, also contain the powder blue as minor component, silicon oxide, vanadium oxide, quicklime and the niobium oxides of specified amount respectively.

Industrial applicability

The method of manufacture of MnZn based ferrite of the present invention can be widely used in the various electric component industries.

Claims (4)

1. wave absorber that comprises MnZn based ferrite sintered compact, this wave absorber contains following principal constituent:

Be converted into Fe ₂O ₃Be 45.0～49.0 moles of % red stone,

Be converted into zinc oxide that ZnO is 19.0～23.0 moles of % and

Be converted into MnO and be 28.0～36.0% manganese oxide,

In addition, with respect to the said principal constituent of 100 weight parts, also contain following minor component:

Be converted into powder blue that CoO is 1000～7000 ppm by weight, be converted into SiO ₂Be 10～200 ppm by weight silicon oxide, be converted into V ₂O ₅Be 50～1000 ppm by weight vanadium oxide, to be converted into CaO be the quicklime of 200～2500 ppm by weight and be converted into Nb ₂O ₅It is the niobium oxides of 50～500 ppm by weight.

2. the described wave absorber of claim 1, wherein, it is 3500～6500 ppm by weight that above-mentioned powder blue is converted into CoO.

3. the described wave absorber of claim 1, it has property:

Tc is more than 80 ℃;

Sintered density is greater than 4.7 (g/cm ³);

The value of the real component ε ' of the complex permittivity under frequency 30MHz satisfies the condition of 10＜ε '＜30;

The value of the real component μ ' of the complex magnetic permeability under frequency 30MHz satisfies the condition of μ '＜80;

The imaginary component μ of the complex magnetic permeability under frequency 30MHz " value satisfy μ "＞260 condition;

Matching thickness is below the 6mm;

Return loss under 25 ℃ is more than the 20dB; And

The La Tuola value is below 0.5%.

4. the described wave absorber of claim 1, this wave absorber forms tabular ceramic tile shape.