WO2015152048A1 - Fe-Co合金粉末およびその製造方法並びにアンテナ、インダクタおよびEMIフィルタ - Google Patents
Fe-Co合金粉末およびその製造方法並びにアンテナ、インダクタおよびEMIフィルタ Download PDFInfo
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- H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
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- H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
- H01R13/66—Structural association with built-in electrical component
- H01R13/719—Structural association with built-in electrical component specially adapted for high frequency, e.g. with filters
Definitions
- the present invention relates to a metal magnetic powder that is advantageous for improving the relative permeability in the several hundred MHz to several GHz band, and a method for producing the same.
- Patent Documents 1 and 2 disclose metal magnetic powders in which the real part ⁇ ′ of the complex relative permeability is increased. However, the loss coefficient tan ⁇ ( ⁇ ) of the complex relative permeability that is an index of magnetic loss is not necessarily described. A sufficient improvement effect has not been obtained.
- ⁇ ′ is a real part of the complex relative permeability.
- ⁇ ′′ is the imaginary part of the complex relative permeability.
- ⁇ s tends to increase as the Co content ratio increases.
- ⁇ ′ is not sufficiently high although ⁇ s is increased.
- the present invention provides an Fe—Co alloy powder suitable for an antenna having a high saturation magnetization ⁇ s, a controlled coercive force Hc, and an extremely large ⁇ ′ and a sufficiently small tan ⁇ ( ⁇ ). And an antenna using the same.
- the present invention provides an Fe—Co alloy powder having an average particle diameter of 100 nm or less, a coercive force Hc of 52.0 to 78.0 kA / m, and a saturation magnetization ⁇ s (Am 2 / kg). Is greater than or equal to 160 Am 2 / kg.
- the ⁇ s satisfies, for example, the following formula (1) in relation to the Co / Fe molar ratio. ⁇ s ⁇ 50 [Co / Fe] +151 (1)
- [Co / Fe] means the molar ratio of Co and Fe in the chemical composition of the powder.
- the Co / Fe molar ratio of the Fe—Co alloy powder is, for example, 0.15 to 0.50.
- the real part ⁇ ′ of the complex relative permeability is 2 at 1 GHz. It is preferable that the loss coefficient tan ⁇ ( ⁇ ) of the complex relative permeability is 0.50 or more and less than 0.05. Further, at 2 GHz, the real part ⁇ ′ of the complex relative permeability is preferably 2.80 or more, and the loss factor tan ⁇ ( ⁇ ) of the complex relative permeability is preferably less than 0.12, and tan ⁇ ( ⁇ ) Can be managed to be less than 0.10.
- the real part ⁇ ′ of the complex relative permeability is 3.00 or more and the loss coefficient tan ⁇ ( ⁇ ) of the complex relative permeability is less than 0.30.
- the electrical resistance of the powder is measured by applying a voltage of 10 V while applying a vertical load of 25 MPa (8 kN) by sandwiching 1.0 g of metal powder between the electrodes by a double ring electrode method according to JIS K6911.
- the volume resistivity is preferably 1.0 ⁇ 10 8 ⁇ ⁇ cm or more.
- an oxidant is introduced into an aqueous solution containing Fe ions and Co ions to form nuclei, and a precursor having Fe and Co as components is precipitated and grown.
- a step of obtaining a precursor by adding Co in an amount corresponding to 40% or more of the total amount of Co used in the reaction to the aqueous solution after the start of nucleation and before the end of the precipitation reaction (precursor formation step);
- the total amount of Co used for the precipitation reaction and the Co / Fe molar ratio in the range of 0.15 to 0.50 are more preferable.
- the nuclei can be generated in the state where a rare earth element (Y is also treated as a rare earth element) is present in the aqueous solution.
- the addition amount of the rare earth element added before the nucleation crystal is formed the axial ratio of the particles constituting the obtained precursor and the finally obtained metal magnetic powder can be changed.
- the above-described precipitation growth can be advanced in a state where one or more of rare earth elements (Y is also treated as a rare earth element), Al, Si, and Mg are present in the aqueous solution.
- the present invention also provides an antenna formed using the Fe—Co alloy powder.
- an antenna that receives, transmits, or transmits / receives a radio wave having a frequency of 430 MHz or more having a molded body obtained by mixing the Fe—Co alloy powder with a resin composition as a constituent member is suitable.
- an inductor and an EMI filter formed using the Fe—Co alloy powder are provided.
- the saturation magnetization ⁇ s when compared at the same Co content can be significantly improved as compared with the conventional case.
- An increase in coercive force Hc accompanying an increase in Co content is also suppressed.
- Improvement of ⁇ s and suppression of Hc are extremely advantageous for improvement of the real part ⁇ ′ of the complex relative magnetic permeability, which is important as high frequency characteristics.
- the axial ratio of the powder particles can be appropriately controlled, and an increase in magnetic loss tan ⁇ ( ⁇ ) is also suppressed. Therefore, the present invention contributes to miniaturization and high performance of high frequency antennas and the like. Further, the present invention contributes to miniaturization and high performance of not only high frequency antennas but also high frequency components such as inductors and EMI filters.
- the Co content in the Fe—Co alloy powder is expressed by the molar ratio of Co to Fe. This molar ratio is called “Co / Fe molar ratio”.
- the saturation magnetization ⁇ s tends to increase as the Co / Fe molar ratio increases.
- ⁇ s higher than that of a conventional general Fe—Co alloy powder can be obtained.
- the ⁇ s improvement effect is obtained in a wide Co content range. For example, an Fe—Co alloy powder having a Co / Fe molar ratio of 0.05 to 0.80 can be targeted.
- the Co / Fe molar ratio is preferably 0.15 or more, more preferably 0.20 or more.
- the Co / Fe molar ratio is desirably 0.70 or less, and 0.60. More preferably, it is more preferably 0.50 or less. According to the present invention, even when the Co / Fe molar ratio is 0.40 or less, or even 0.35 or less, high ⁇ s can be obtained.
- rare earth elements As a metal element other than Fe and Co, one or more of rare earth elements (Y is also handled as a rare earth element), Al, Si, and Mg can be contained. Rare earth elements, Si, Al, and Mg are added as necessary in a conventionally known metal magnetic powder production process, and the inclusion of these elements is allowed in the present invention.
- a typical example of the rare earth element added to the metal magnetic powder is Y.
- the rare earth element / (Fe + Co) molar ratio can be 0 to 0.20, more preferably 0.001 to 0.05.
- the Si / (Fe + Co) molar ratio can be 0 to 0.30, more preferably 0.01 to 0.15.
- the Al / (Fe + Co) molar ratio can be 0 to 0.20, more preferably 0.01 to 0.15.
- the Mg / (Fe + Co) molar ratio can be 0 to 0.20.
- the particle diameter of the particles constituting the metal magnetic powder can be determined by observation with a transmission electron microscope (TEM).
- the diameter of the smallest circle surrounding the particle on the TEM image is defined as the particle diameter (major axis).
- the diameter means a diameter including an oxidation protective layer covering the periphery of the metal core.
- the diameter of 300 randomly selected particles can be measured, and the average value can be used as the average particle diameter of the metal magnetic powder.
- the average particle size is 100 nm or less.
- an ultrafine powder having an average particle diameter of less than 10 nm is accompanied by an increase in production cost and a decrease in handleability, the average particle diameter is usually 10 nm or more.
- the “average axial ratio” which is an average axial ratio as a powder can be determined as follows. By TEM observation, “major axis” and “minor axis” were measured for 300 particles selected at random, and the average value of the major axis and the average value of the minor axis for all particles to be measured were “average major axis” and “ The ratio of average major axis / average minor axis is defined as “average axis ratio”.
- the average axial ratio of the Fe—Co alloy powder according to the present invention is desirably in the range of more than 1.40 and less than 1.70. If it is 1.40 or less, the imaginary part ⁇ ′′ of the complex relative permeability increases due to the reduction of the shape magnetic anisotropy, which is disadvantageous for applications in which the reduction of the loss coefficient ⁇ ( ⁇ ) is important. When the average axial ratio exceeds 1.70, the effect of improving the saturation magnetization ⁇ s tends to be small, and the merit is reduced in an application that emphasizes the improvement of the real part ⁇ ′ of the complex relative permeability.
- the coercive force Hc is desirably 52.0 to 78.0 kA / m. If Hc is too low, tan ⁇ ( ⁇ ) becomes large in the characteristics of a frequency of 430 MHz or more, and the loss increases when used for an antenna. On the other hand, if Hc is too high, it causes a reduction in the real part ⁇ ′ of the complex relative permeability in the high frequency characteristics. In this case, the improvement effect of ⁇ ′ due to the increase in ⁇ s is offset, which is not preferable. More preferably, Hc is less than 70.0 kA / m. By adopting a Co addition method described later, the above-described coercive force range can be controlled.
- the saturation magnetization ⁇ s (Am 2 / kg) satisfies the following formula (1) in relation to the Co / Fe molar ratio.
- [Co / Fe] means the molar ratio of Co and Fe in the chemical composition of the powder.
- the metal magnetic powder satisfying the formula (1) exhibits a high ⁇ s at a smaller amount of Co addition than the conventional general Fe—Co alloy powder, and can save the use amount of Co more expensive than Fe. Excellent cost performance.
- an Fe—Co powder satisfying the formula (1) and having the coercive force Hc adjusted to the above range could not be obtained in the past, and is particularly advantageous for improving ⁇ ′ in high frequency characteristics.
- ⁇ s is adjusted to 160 Am 2 / kg or more.
- ⁇ s may be in a range of 200 Am 2 / kg or less.
- ⁇ s satisfying the expression (1) can be realized.
- Other powder characteristics include a BET specific surface area of 30 to 70 m 2 / g, a TAP density of 0.8 to 1.5 g / cm 3 , a squareness ratio SQ of 0.3 to 0.6, and an SFD of 3.5 or less. Each is preferably in the range.
- ⁇ s representing the change rate of ⁇ s before and after the test in which the metal magnetic powder is held in an air environment at a temperature of 60 ° C. and a relative humidity of 90% for one week is preferably 15% or less.
- ⁇ s (%) is calculated by ( ⁇ s before test ⁇ s after test) / ⁇ s ⁇ 100 before test.
- the resistivity is preferably 1.0 ⁇ 10 8 ⁇ ⁇ cm or more.
- the magnetic permeability and dielectric constant expressed by the Fe—Co alloy powder can be evaluated.
- a known thermosetting resin such as an epoxy resin or a known thermoplastic resin can be employed.
- the real part ⁇ ′ of the complex relative permeability is 2.50 or more, and the loss coefficient tan ⁇ ( ⁇ ) of the complex relative permeability is less than 0.05. More preferably, ⁇ ′ is 2.70 or more and tan ⁇ ( ⁇ ) is less than 0.03. This tan ⁇ ( ⁇ ) is preferably as small as possible, but it may be adjusted in the range of usually 0.005 or more.
- the Fe—Co alloy powder according to the present invention exhibits excellent magnetic properties even in a frequency range exceeding 1 GHz.
- exemplifying the 2 GHz high-frequency characteristics in the above-mentioned molded body those having the property that ⁇ ′ is 2.80 or more and tan ⁇ ( ⁇ ) is less than 0.12 or less than 0.10 are suitable targets.
- ⁇ ′ is 2.80 or more and tan ⁇ ( ⁇ ) is 0.300 or less, more preferably 0.250 or less are suitable targets.
- 1 GHz ⁇ ′ is 3.50 or more, tan ⁇ ( ⁇ ) is less than 0.025, 2 GHz ⁇ ′ is 3.80 or more, tan ⁇ ( ⁇ ) is less than 0.12, and 3 GHz. It is also possible to make different Fe—Co alloy powders that can exhibit extremely high frequency characteristics such that ⁇ ′ is 4.00 or more and tan ⁇ ( ⁇ ) is less than 0.30.
- the above-mentioned Fe—Co magnetic powder can be manufactured by the following steps.
- Precursor forming step An oxidant is introduced into an aqueous solution in which Fe ions and Co ions are dissolved to generate nuclei, and a precursor having Fe and Co as components is precipitated and grown.
- an amount of Co corresponding to 40% or more of the total amount of Co used for the precipitation reaction is added to the aqueous solution at a time after the start of nucleation and before the end of the precipitation reaction.
- An amount of Co corresponding to the above is added after the start of nucleation and before the end of the precipitation reaction.
- reaction source solution aqueous solution before the start of nucleation generation
- initial stage the time before the start of nucleation generation
- intermediate stage the period after the start of nucleation generation (that is, after the start of oxidant introduction) and before the end of the precipitation reaction is called “intermediate stage”, and the operation of adding a water-soluble substance to the liquid and dissolving it in the intermediate stage Called “addition”.
- At least Fe ions must be present in the reaction source solution.
- a water-soluble iron compound iron sulfate, iron nitrate, iron chloride, etc.
- an alkali hydroxide NaOH, KOH, etc.
- an alkali carbonate sodium carbonate, ammonium carbonate, etc.
- An aqueous solution containing divalent Fe ions obtained by neutralization is preferred.
- Co source water-soluble cobalt compounds (such as cobalt sulfate, cobalt nitrate, and cobalt chloride) can be used.
- an oxygen-containing gas such as air, hydrogen peroxide, or the like can be used.
- Precursor nuclei are generated by passing an oxygen-containing gas through the reaction source solution or adding an oxidant substance such as hydrogen peroxide. Thereafter, the introduction of an oxidizing agent is further continued to deposit an Fe compound or further a Co compound on the surface of the nucleus crystal to grow precursor particles.
- the precursor is considered to be mainly composed of crystals of iron oxyhydroxide or a structure in which part of Fe site of iron oxyhydroxide is substituted with Co.
- the Co content in the initial stage can be reduced.
- the precursor can be precipitated and grown in a state where the amount of dissolved Co is small, and an increase in the axial ratio is suppressed. It can be seen that even when a large amount of Co is added after the precursor particles have already grown to some extent, unlike the growth from the nucleus crystal stage, the decrease in precipitation preferentially in the major axis direction is alleviated. It was. In this way, precursor particles having a smaller axial ratio can be obtained even though the total Co content is the same.
- This particle is considered to have a higher Co concentration in the peripheral part than in the central part, but it is considered that the concentration fluctuations of Fe and Co are homogenized by atomic diffusion during the reduction firing. It is effective that the amount of Co added during the process is equivalent to 40% or more of the total amount of Co used in the precipitation reaction.
- the method of adding Co in the middle can be performed by directly adding the water-soluble cobalt compound described above or by adding a solution in which Co is dissolved beforehand.
- One-time addition, divided addition, and continuous addition can be appropriately selected.
- an amount of Co corresponding to 40% or more of the total amount of Co is added halfway after the time when 10% of the total amount of Fe used for the precipitation reaction is oxidized (ie, consumed for the precipitation reaction). More preferably, an amount of Co corresponding to 40% or more of the total Co amount is added halfway after the time point when 20% of the total Fe amount used is oxidized.
- precipitation growth of the precursor can proceed in a state where one or more of rare earth elements (Y is also treated as a rare earth element), Al, Si, and Mg are present in the aqueous solution.
- the addition timing of these elements may be any of an initial stage, an intermediate stage, an initial stage, and an intermediate stage.
- Each water-soluble compound may be used as a supply source of these elements.
- the water-soluble rare earth element compound include yttrium sulfate, yttrium nitrate, and yttrium chloride in the case of an yttrium compound.
- the water-soluble aluminum compound include aluminum sulfate, aluminum chloride, aluminum nitrate, sodium aluminate, and potassium aluminate.
- the water-soluble silicon compound examples include sodium silicate, sodium orthosilicate, potassium silicate and the like.
- the water-soluble magnesium compound examples include magnesium sulfate, magnesium chloride, and magnesium nitrate.
- the rare earth element / (Fe + Co) molar ratio is preferably in the range of 0.20 or less, and may be controlled in the range of 0.001 to 0.05.
- the Al / (Fe + Co) molar ratio is preferably in the range of 0.20 or less, and may be controlled in the range of 0.01 to 0.15.
- the Si / (Fe + Co) molar ratio is preferably in the range of 0.30 or less, and may be controlled in the range of 0.01 to 0.15.
- the Mg / (Fe + Co) molar ratio is preferably in the range of 0.20 or less, and may be controlled in the range of 0.01 to 0.15.
- a metal powder having an Fe—Co alloy phase is obtained.
- a typical example of the reducing gas is hydrogen gas.
- the heating temperature can be in the range of 250 to 650 ° C, more preferably 500 to 650 ° C.
- the heating time may be adjusted in the range of 10 to 120 min.
- the metal powder that has undergone the reduction process may be rapidly oxidized when exposed to the air as it is.
- the stabilization step is a step of forming an oxidation protective layer on the particle surface while avoiding rapid oxidation.
- the atmosphere to which the reduced metal powder is exposed is an inert gas atmosphere, and the oxidation reaction of the surface part of the metal powder particles proceeds at 20 to 300 ° C., more preferably 50 to 300 ° C. while increasing the oxygen concentration in the atmosphere.
- the metal powder may be transferred to another heat treatment apparatus to perform the stabilization process.
- a stabilization process can also be implemented continuously, moving a metal powder with a conveyor etc. after a reduction process. In any case, it is important to transfer the metal powder to the stabilization step after the reduction step without exposing the metal powder to the atmosphere.
- the inert gas one or more gas components selected from a rare gas and a nitrogen gas can be applied. Pure oxygen gas or air can be used as the oxygen-containing gas. Steam may be introduced together with the oxygen-containing gas. Water vapor has the effect of densifying the oxide film.
- the oxygen concentration is finally 0.1 to 21% by volume.
- the introduction of the oxygen-containing gas can be performed continuously or intermittently. In the initial stage of the stabilization process, it is more preferable to keep the time during which the oxygen concentration is 1.0 vol% or less for 5.0 min or more.
- the Fe—Co alloy powder according to the present invention can be used as a constituent material of an antenna.
- a planar antenna having a conductor plate and a radiation plate arranged in parallel to the conductor plate can be mentioned.
- the configuration of the planar antenna is disclosed in FIG.
- the Fe—Co alloy powder according to the present invention is extremely useful as a magnetic material for an antenna that transmits, receives, or transmits / receives radio waves of 430 MHz or higher.
- application to an antenna used in a frequency band of 700 MHz to 6 GHz is more effective.
- thermosetting resin or thermoplastic resin may be applied as the resin.
- the thermosetting resin can be selected from phenol resin, epoxy resin, unsaturated polyester resin, isocyanate compound, melamine resin, urea resin, silicone resin, and the like.
- the epoxy resin either a monoepoxy compound, a polyvalent epoxy compound, or a mixture thereof can be used.
- Various monoepoxy compounds and polyvalent epoxy compounds are exemplified in Patent Document 3, and they can be appropriately selected and used.
- thermoplastic resins polyvinyl chloride resin, ABS resin, polypropylene resin, polyethylene resin, polystyrene resin, acrylonitrile styrene resin, acrylic resin, polyethylene terephthalate resin, polyphenylene ether resin, polysulfone resin, polyarylate resin, polyetherimide Resin, polyetheretherketone resin, polyethersulfone resin, polyamide resin, polyamideimide resin, polycarbonate resin, polyacetal resin, polybutylene terephthalate resin, polyetheretherketone resin, polyethersulfone resin, liquid crystal polymer (LCP), fluorine It can be selected from resin, urethane resin and the like.
- LCP liquid crystal polymer
- the mixing ratio of the Fe—Co alloy powder and the resin is preferably 30/70 or more and 99/1 or less, more preferably 50/50 or more and 95/5 or less, expressed as a mass ratio of metal magnetic powder / resin, and 70 / More preferably, it is 30 or more and 90/10 or less. If the amount of resin is too small, a molded body is not obtained, and if it is too large, desired magnetic properties cannot be obtained.
- Example 1 [Preparation of reaction source solution] A 1 mol / L ferrous sulfate aqueous solution and a 1 mol / L cobalt sulfate aqueous solution are mixed so that the molar ratio of Fe: Co is 100: 10 to obtain an approximately 800 mL solution, and 0.2 mol / L sulfuric acid is added thereto. An aqueous yttrium solution was added so that the Y / (Fe + Co) molar ratio was 0.026 to prepare an approximately 1 L Fe, Co, Y-containing solution.
- reaction source solution To a 5000 mL beaker, 2600 mL of pure water and 350 mL of an ammonium carbonate solution were added and stirred while maintaining the temperature at 40 ° C. with a temperature controller to obtain an aqueous ammonium carbonate solution.
- concentration of the ammonium carbonate solution was adjusted so that CO 3 2 ⁇ carbonate was 3 equivalents with respect to Fe 2+ in the Fe, Co, and Y-containing solution.
- the Fe, Co, and Y-containing solution was added to the aqueous ammonium carbonate solution to obtain a reaction source solution.
- the charged Co / Fe molar ratio in the initial stage (reaction source solution) is 0.10.
- composition analysis The composition of the sample powder was analyzed with an ICP emission spectrometer. The results are shown in Table 1.
- Average particle diameter, average axial ratio About the test powder, the average particle diameter and the average axial ratio were measured by the above-mentioned method by TEM observation. The results are shown in Table 1.
- the volume resistivity of the test powder was determined by applying a vertical load of 13 to 64 MPa (4 to 20 kN) with 1.0 g of the test powder sandwiched between the electrodes by the double ring electrode method according to JIS K6911. It calculated
- a powder resistance measurement unit (MCP-PD51) manufactured by Mitsubishi Chemical Analytech a high resistance resistivity meter Hiresta UP (MCP-HT450) manufactured by Mitsubishi Chemical, and a high resistance powder measurement system software manufactured by the company were used. The results are shown in Table 2.
- MCP-PD51 powder resistance measurement unit
- MCP-HT450 high resistance resistivity meter Hiresta UP
- the results are shown in Table 2.
- BET specific surface area The BET specific surface area was determined by the BET single point method using 4 Sorb US manufactured by Yuasa Ionics. The results are shown in Table 2.
- TAP density The TAP density was measured by putting the test powder in a glass sample cell (5 mm diameter ⁇ 40
- Magnetic properties and weather resistance of powder As a magnetic property (bulk property) of the test powder, using a VSM apparatus (manufactured by Toei Kogyo Co., Ltd .; VSM-7P), an external magnetic field of 795.8 kA / m (10 kOe) and a coercive force Hc (kA / m) The saturation magnetization ⁇ s (Am 2 / kg) and the squareness ratio SQ were measured. The weather resistance was evaluated by the change rate ⁇ s of ⁇ s before and after the test in which the metal magnetic powder was kept in an air environment at a temperature of 60 ° C. and a relative humidity of 90% for 1 week.
- ⁇ s is calculated by ( ⁇ s before test ⁇ s after test) / ⁇ s ⁇ 100 before test. These results are shown in Table 3. Table 3 shows the value on the right side of the equation (1) and the difference between the value of ⁇ s (Am 2 / kg) and the value on the right side of the equation (1). Equation (1) is satisfied when the difference between ⁇ s and the value on the right side of Equation (1) is 0 or positive.
- test powder and epoxy resin manufactured by Tesque Co., Ltd .; one-component epoxy resin B-1106
- a vacuum agitation / defoaming mixer manufactured by EME; V-mini300
- EME vacuum agitation / defoaming mixer
- a network analyzer manufactured by Agilent Technologies; E5071C
- a coaxial S-parameter method sample holder kit manufactured by Kanto Electronics Application Development Co., Ltd .; CSH2-APC7, sample dimensions: ⁇ 7.0 mm- ⁇ 3.04 mm ⁇ 5 mm)
- CSH2-APC7 sample dimensions: ⁇ 7.0 mm- ⁇ 3.04 mm ⁇ 5 mm
- Example 2 and 3 The experiment was performed under the same conditions as in Example 1, except that the Co / Fe molar ratio added during the course was increased to 0.15 (Example 2) and 0.20 (Example 3), respectively.
- the production conditions and results are shown in Tables 1 to 4 as in Example 1 (the same applies in the following examples).
- Example 4 When growing the precursor, the experiment was performed under the same conditions as in Example 2 except that the air blowing speed after addition of Co in the middle was reduced to 81.5 mL / min.
- Example 5 When growing the precursor, the experiment was performed under the same conditions as in Example 3 except that the air blowing speed after addition of Co in the middle was reduced to 40.8 mL / min.
- Example 6 The experiment was performed under the same conditions as in Example 5 except that the addition ratio of Co / Fe added during the course was increased to 0.25.
- Example 7 The experiment was performed under the same conditions as in Example 5 except that the initial charge Co / Fe molar ratio was increased to 0.15 and the intermediate charge Co / Fe molar ratio was decreased to 0.15.
- Example 8 After the stabilization treatment, an experiment was performed under the same conditions as in Example 4 except that the reduction treatment and the stabilization treatment were performed once again in the same furnace. In this case, the conditions for the second reduction treatment and the stabilization treatment were the same as the conditions for the first reduction treatment and the stabilization treatment, respectively (the same applies to Examples 9 and 10 below).
- Example 9 After the stabilization treatment, an experiment was performed under the same conditions as in Example 5 except that the reduction treatment and the stabilization treatment were performed once again in the same furnace.
- Example 10 After the stabilization treatment, an experiment was performed under the same conditions as in Example 6 except that the reduction treatment and the stabilization treatment were performed once again in the same furnace.
- Example 11 An experiment was performed under the same conditions as in Example 9 except that the temperature of the stabilization treatment was changed to 70 ° C.
- Example 12 An experiment was performed under the same conditions as in Example 10 except that the temperature of the stabilization treatment was changed to 70 ° C.
- Example 13 When the precursor was grown, the experiment was performed under the same conditions as in Example 12 except that the air blowing speed after addition of Co in the middle was reduced to 34.6 mL / min.
- Example 14 In the precursor formation process, the liquid temperature after generating iron oxyhydroxide nuclei was 50 ° C., and air was passed through the liquid until 40% of the total Fe 2+ present in the reaction source liquid was oxidized. The experiment was performed under the same conditions as in Example 13 except that the air blowing speed was 106 mL / min.
- Example 15 The experiment was performed under the same conditions as in Example 14 except that the initial charge Co / Fe molar ratio was 0.08 and the intermediate addition Co / Fe molar ratio was 0.27.
- Example 16 The initial stage charge Co / Fe molar ratio was set to 0.08, and the addition Co / Fe molar ratio during intermediate addition was set to 0.27. In the precursor formation process, after the intermediate addition of Co, the oxidation was completed. The experiment was performed under the same conditions as in Example 13 except that the liquid temperature during air blowing was changed from 60 ° C to 55 ° C.
- Comparative Examples 1 to 5 >> In Comparative Examples 1, 2, 3, 4 and 5, the initial stage charge Co / Fe molar ratio was set to 0.05, 0.10, 0.15, 0.20 and 0.25, respectively, and Co was added in the middle In all cases, the experiment was performed under the same conditions as in Example 1.
- FIG. 1 shows the relationship between the total Co / Fe molar ratio (analysis value) and the saturation magnetization ⁇ s in each of the above examples. It can be seen that each of the examples in which Co was added during the process of growing the precursor had a greater effect of increasing ⁇ s with an increase in Co content than the comparative example in which Co was not added in the middle. .
- the boundary line of the equation (1) is shown. When the precursor is grown by the technique of adding Co in the middle, a remarkable ⁇ s increasing effect that satisfies the equation (1) is obtained.
- the white square plots are examples 8 to 10 in which the reduction treatment and the stabilization treatment are repeated for a total of two sets, and the white triangle plots are set at a stabilization treatment temperature of 70 ° C.
- Examples 11 to 13 in which reduction processing and stabilization processing were repeated for a total of two sets were performed, and white inverted triangular plots were examples 14 to 16 (the same applies in FIG. 2 described later). For these, a more remarkable effect of increasing ⁇ s was obtained.
- FIG. 2 shows the relationship between the total Co / Fe molar ratio (analytical value) and the coercive force Hc in each example. It can be seen that the increase in the coercive force Hc was suppressed in the examples in which Co was added during the process of growing the precursor, compared to the comparative example in which Co was not added in the middle.
- the real part ⁇ ′ of the complex relative magnetic permeability at 1 to 3 GHz is remarkably improved in the example in comparison with the comparative example. This is considered to be due to the fact that the Fe—Co alloy powder of the example has a high ⁇ s and the increase in Hc is suppressed. In addition, the loss factor tan ⁇ ( ⁇ ) is kept low in the example, although ⁇ ′ is improved. This is considered to be due to the fact that the average axial ratio of the Fe—Co alloy powder is controlled within an appropriate range so as not to become too small by the intermediate addition of Co.
Abstract
Description
σs≧50[Co/Fe]+151 …(1)
ここで、[Co/Fe]は粉体の化学組成におけるCoとFeのモル比を意味する。
前駆体の乾燥物を還元性ガス雰囲気中で250~650℃に加熱することにより、Fe-Co合金相を持つ金属粉末を得る工程(還元工程)、
還元後の金属粉末粒子の表層部に酸化保護層を形成する工程(安定化工程)、
さらに必要に応じて、還元性ガス雰囲気中での250~650℃の加熱処理と、それに続く前記安定化工程の処理を1回以上実施する工程(還元・安定化反復工程)、
を有する製造方法が提供される。
発明者らは詳細な研究の結果、水溶液中で前駆体を析出成長させ、その前駆体を還元焼成してFe-Co合金磁性粉末を得るに際し、析出反応に使用されるCoの一部を、前駆体が析出成長する過程の途中段階で液中に追加添加する手法を採用したとき、保磁力Hcの過度な増大を伴わずに飽和磁化σsを顕著に向上させることができることを見出した。その結果、tanδ(μ)を低く抑えながらμ’を顕著に向上させることが可能となる。本発明はこのような知見に基づいて完成したものである。
〔化学組成〕
本明細書において、Fe-Co合金粉末におけるCo含有量は、CoとFeのモル比によって表す。このモル比を「Co/Feモル比」と呼ぶ。一般に、Co/Feモル比の増加に伴って飽和磁化σsが増大する傾向がある。本発明に従えば、同じCo/Feモル比で比べると、従来一般的なFe-Co合金粉末よりも高いσsが得られる。そのσs改善効果は広いCo含有量範囲において得られる。例えばCo/Feモル比が0.05~0.80のFe-Co合金粉末を対象とすることができる。高周波用アンテナ等、高いσsを必要とする用途を考慮すると、Co/Feモル比は0.15以上であることが好ましく、0.20以上がより好ましい。高いσsを得る点においてはCoを多く含有することが望ましいが、過剰なCo含有はコスト増を招く要因となるため、Co/Feモル比は0.70以下とすることが望ましく、0.60以下とすることがより好ましく、0.50以下とすることがさらに好ましい。本発明に従えばCo/Feモル比を0.40以下、あるいはさらに0.35以下の範囲とした場合においても高いσsを得ることができる。
金属磁性粉末を構成する粒子の粒子径は、透過型電子顕微鏡(TEM)観察により求めることができる。TEM画像上である粒子を取り囲む最小円の直径をその粒子の径(長径)と定める。その径は、金属コアの周囲を覆う酸化保護層を含めた径を意味する。ランダムに選択した300個の粒子について径を測定し、その平均値を当該金属磁性粉末の平均粒子径とすることができる。本発明では、平均粒子径が100nm以下のものを対象とする。一方、平均粒子径が10nm未満の超微細粉末は、製造コストの上昇や取り扱い性の低下を伴うので、通常、平均粒子径は10nm以上とすればよい。
TEM画像上のある粒子について、上記の「長径」に対して直角方向に測った最も長い部分の長さを「短径」と呼び、長径/短径の比をその粒子の「軸比」と呼ぶ。粉末としての平均的な軸比である「平均軸比」は以下のようにして定めることができる。TEM観察により、ランダムに選択した300個の粒子について「長径」と「短径」を測定し、測定対象の全粒子についての長径の平均値および短径の平均値をそれぞれ「平均長径」および「平均短径」とし、平均長径/平均短径の比を「平均軸比」と定める。本発明に従うFe-Co合金粉末の平均軸比は、1.40より大きく1.70未満の範囲であることが望ましい。1.40以下になると形状磁気異方性が小さくなることに起因して複素比透磁率の虚数部μ”が大きくなり、損失係数δ(μ)の低下を重視する用途では不利となる。一方、平均軸比が1.70を超えると飽和磁化σsの向上効果が小さくなりやすく、複素比透磁率の実数部μ’の向上を重視する用途ではメリットが低減する。
保磁力Hcは52.0~78.0kA/mであることが望ましい。Hcが低すぎると周波数430MHz以上の特性においてtanδ(μ)が大きなものとなり、アンテナに使用する際に損失が増大する。一方、Hcが高すぎると高周波特性において複素比透磁率の実数部μ’を低下させる要因となる。この場合、σsの増大によるμ’の向上効果が相殺され好ましくない。Hcは70.0kA/m未満であることがより好ましい。後述のCo添加手法を採用することにより、上述の保磁力範囲にコントロールすることができる。
σs≧50[Co/Fe]+151 …(1)
ここで、[Co/Fe]は粉体の化学組成におけるCoとFeのモル比を意味する。
(1)式を満たす金属磁性粉末は、従来一般的なFe-Co合金粉末と比べ、より少ないCo添加量において高いσsを呈するものであり、Feよりも高価なCoの使用量を節約できる点でコストパフォーマンスに優れる。また、(1)式を満たし、かつ保磁力Hcを上述の範囲に調整したFe-Co粉末は従来得ることができなかったものであり、高周波特性において特にμ’の向上に有利である。平面アンテナ等の高周波用途では、σsが160Am2/kg以上に調整されていることが好ましい。σsが160Am2/kgよりも小さい場合はμ’が小さくなり、アンテナに使用した際の小型化効果が小さなものとなる。なお、σsは通常、200Am2/kg以下の範囲にあればよい。後述のCo添加手法を採用することにより、(1)式を満たすσsを実現することができる。
なお、上記(1)式に代え、下記(2)式を満たすもの、あるいは下記(3)式を満たすものを得ることも可能である。
σs≧50[Co/Fe]+157 …(2)
σs≧50[Co/Fe]+161 …(3)
Fe-Co合金粉末と樹脂を90:10の質量割合で混合して作製したトロイダル形状のサンプルを用いて、当該Fe-Co合金粉末によって発現する透磁率・誘電率を評価することができる。その際に使用する樹脂としては、エポキシ樹脂をはじめとする公知の熱硬化性樹脂や、公知の熱可塑性樹脂が採用できる。このような成形体としたとき、1GHzにおいて、複素比透磁率の実数部μ’が2.50以上、複素比透磁率の損失係数tanδ(μ)が0.05未満となる性質を有することが好ましく、μ’が2.70以上、tanδ(μ)が0.03未満となる性質を有することがより好ましい。このtanδ(μ)は小さければ小さいほど好ましいが、通常0.005以上の範囲で調整されていればよい。
特に本発明に従えば、1GHzのμ’が3.50以上、tanδ(μ)が0.025未満、2GHzのμ’が3.80以上、tanδ(μ)が0.12未満、かつ3GHzのμ’が4.00以上、tanδ(μ)が0.30未満という極めて優れた高周波特性を発揮させることができるFe-Co合金粉末を作り分けることも可能である。
上記のFe-Co磁性粉末は、以下のような工程で製造することができる。
〔前駆体形成工程〕
FeイオンおよびCoイオンが溶解している水溶液に酸化剤を導入して核晶を生成させ、FeおよびCoを成分に持つ前駆体を析出成長させる。ただし、析出反応に使用する全Co量の40%以上に相当する量のCoを、核晶生成開始後かつ析出反応終了前の時期に前記水溶液中に添加する。例えば、析出反応に使用する全Co量が、Co/Feモル比で0.30である場合、その40%以上、すなわちCo/Feモル比で0.30×(40/100)=0.12以上に相当する量のCoを、核晶生成開始後かつ析出反応終了前の時期に添加する。以下において、核晶生成開始前(すなわち酸化剤導入開始前)の水溶液を「反応元液」と呼び、核晶生成開始前の時期を「初期段階」と呼ぶ。また、核晶生成開始後(すなわち酸化剤導入開始後)かつ析出反応終了前の時期を「途中段階」と呼び、途中段階で水溶性の物質を液中に添加して溶解させる操作を「途中添加」と呼ぶ。
上記の方法で得られた前駆体の乾燥物を還元性ガス雰囲気中で加熱することにより、Fe-Co合金相を持つ金属粉末を得る。還元性ガスとしては、代表的には水素ガスが挙げられる。加熱温度は250~650℃の範囲とすることができ、500~650℃がより好ましい。加熱時間は10~120minの範囲で調整すればよい。
還元工程を終えた金属粉末は、そのまま大気に曝すと急速に酸化するおそれがある。安定化工程は、急激な酸化を回避しながら粒子表面に酸化保護層を形成する工程である。還元後の金属粉末が曝される雰囲気を不活性ガス雰囲気とし、当該雰囲気中の酸素濃度を増大させながら20~300℃、より好ましくは50~300℃で金属粉末粒子表層部の酸化反応を進行させる。上記還元工程と同じ炉中で安定化工程を実施する場合は、還元工程を終了後、炉内の還元性ガスを不活性ガスで置換し、上記温度範囲において当該不活性ガス雰囲気中に酸素含有ガスを導入しながら粒子表層部の酸化反応を進行させるとよい。金属粉末を別の熱処理装置に移して安定化工程を実施してもよい。また、還元工程後に金属粉末をコンベア等で移動させながら連続的に安定化工程を実施することもできる。いずれの場合も、還元工程後に、金属粉末を大気に曝すことなく、安定化工程に移行させることが重要である。不活性ガスとしては、希ガスおよび窒素ガスから選ばれる1種以上のガス成分が適用できる。酸素含有ガスとしては、純酸素ガスや空気が使用できる。酸素含有ガスとともに、水蒸気を導入してもよい。水蒸気は酸化皮膜を緻密化させる効果がある。金属磁性粉末を30~300℃好ましくは50~300℃に保持するときの酸素濃度は、最終的には0.1~21体積%とする。酸素含有ガスの導入は、連続的または間欠的に行うことができる。安定化工程の初期の段階で、酸素濃度が1.0体積%以下である時間を5.0min以上キープすることがより好ましい。
前記安定化工程後に、還元性ガス雰囲気中での250~650℃の加熱処理と、それに続く前記安定化工程の処理を1回以上実施することができる。これにより、Co添加による飽和磁化σsの向上効果を増大させることができる。
本発明に従うFe-Co合金粉末は、アンテナの構成材料として使用できる。例えば、導体板と、それに平行に配置される放射板とを有する平面アンテナが挙げられる。平面アンテナの構成は例えば特許文献3の図1に開示されている。本発明に従うFe-Co合金粉末は、430MHz以上の電波を送信、受信 または送受信するアンテナ用の磁性体素材として極めて有用である。特に700MHz~6GHzの周波数帯域で使用されるアンテナへの適用がより効果的である。
〔反応元液の作成〕
1mol/Lの硫酸第一鉄水溶液と1mol/Lの硫酸コバルト水溶液をFe:Coのモル比が100:10となるように混合して約800mLの溶液とし、これに0.2mol/Lの硫酸イットリウム水溶液をY/(Fe+Co)モル比が0.026となるように加えて、約1LのFe、Co、Y含有溶液を用意した。5000mLビーカーに、純水2600mLと、炭酸アンモニウム溶液350mLを添加し、温調機で40℃に維持しながら撹拌し、炭酸アンモニウム水溶液を得た。なお、炭酸アンモニウム溶液の濃度としては、前記Fe、Co、Y含有溶液中のFe2+に対し炭酸CO3 2-が3当量となるように調整した。この炭酸アンモニウム水溶液中に前記Fe、Co、Y含有溶液を加え、反応元液とした。本例では、初期段階(反応元液)の仕込みCo/Feモル比は0.10である。
上記の反応元液に3mol/LのH2O2水溶液を5mL添加しオキシ水酸化鉄の核晶を生成させた。その後、この液を60℃に昇温し、反応元液中に存在していた全Fe2+の40%が酸化するまで液中に空気を163mL/minの吹き込み速度で通気した。このときに必要な通気量は、予め予備実験により把握してある。その後、反応元液中のFeの総量に対しCo/Feモル比が0.10(=10モル%)となる量のCoを含有する1mol/Lの硫酸コバルト水溶液を途中添加した。Co途中添加後、0.3mol/Lの硫酸アルミニウム水溶液をFeとCo(途中添加するCoも含む)の総量に対しAl/(Fe+Co)モル比が0.055となるように添加し、酸化が完結するまで(すなわち前駆体の形成反応が終了するまで)空気を163mL/minの吹き込み速度で通気した。このようにして得た前駆体含有スラリーを、濾過、水洗したのち、空気中110℃で乾燥して、前駆体の乾燥物(粉末)を得た。本例では、途中添加の仕込みCo/Feモル比は0.10、トータルの仕込みCo/Feモル比は0.20である。Coの仕込み添加量を表1中に示す。
上記の前駆体の乾燥物を通気可能なバケットに入れ、そのバケットを貫通型還元炉内に装入し、炉内に水素ガスを流しながら630℃で40min保持することにより還元処理を施した。
還元処理後、炉内の雰囲気ガスを水素から窒素に変換し、窒素ガスを流した状態で炉内温度を降温速度20℃/minで80℃まで低下させた。その後、安定化処理を行う初期のガスとして、窒素ガス/空気の体積割合が125/1となるように窒素ガスと空気を混合したガス(酸素濃度約0.17体積%)を炉内に導入して金属粉末粒子表層部の酸化反応を開始させ、その後徐々に空気の混合割合を増大させ、最終的に窒素ガス/空気の体積割合が25/1となる混合ガス(酸素濃度約0.80体積%)を炉内に連続的に導入することにより、粒子の表層部に酸化保護層を形成した。安定化処理中、温度は80℃に維持し、ガスの導入流量もほぼ一定に保った。
以上の工程により、Fe-Co合金相を磁性相に持つ供試粉末を得た。
ICP発光分析装置により供試粉末の組成分析を行った。その結果を表1中に示す。
〔平均粒子径、平均軸比〕
供試粉末について、TEM観察による上述の方法で平均粒子径および平均軸比を測定した。結果を表1中に示す。
供試粉末の体積抵抗率は、JIS K6911に準拠した二重リング電極方法により、供試粉末1.0gを電極間に挟んで13~64MPa(4~20kN)の垂直荷重を付与しながら印加電圧10Vにて測定する方法により求めた。測定には、三菱化学アナリテック社製粉体抵抗測定ユニット(MCP―PD51)、同社製高抵抗抵抗率計ハイレスタUP(MCP-HT450)、同社製高抵抗粉体測定システムソフトウェアを用いた。結果を表2中に示す。
〔BET比表面積〕
BET比表面積は、ユアサアイオニクス社製の4ソーブUSを用いて、BET一点法により求めた。結果を表2中に示す。
〔TAP密度〕
TAP密度は、ガラス製のサンプルセル(5mm径×40mm高さ)に供試粉末を入れ、タップ高さ10cmとして、200回タッピングを行って測定した。結果を表2中に示す。
供試粉末の磁気特性(バルク特性)として、VSM装置(東英工業社製;VSM-7P)を使用して、外部磁場795.8kA/m(10kOe)で、保磁力Hc(kA/m)、飽和磁化σs(Am2/kg)、角形比SQを測定した。耐候性については、金属磁性粉末を温度60℃、相対湿度90%の空気環境に1週間保持する試験前後のσsの変化量率Δσsにより評価した。Δσsは(試験前のσs-試験後のσs)/試験前のσs×100によって算出される。これらの結果を表3中に示す。
また、表3中には前記(1)式右辺の値、およびσs(Am2/kg)と(1)式右辺の値の差を示す。σsと(1)式右辺の値の差が0または正になる場合に(1)式を満たす。
供試粉末とエポキシ樹脂(株式会社テスク製;一液性エポキシ樹脂B-1106)を90:10の質量割合で秤量し、真空撹拌・脱泡ミキサー(EME社製;V-mini300)を用いてこれらを混練し、供試粉末がエポキシ樹脂中に分散したペーストとした。このペーストをホットプレート上で60℃、2h乾燥させて金属粉末と樹脂の複合体としたのち、粉末状に解粒して、複合体粉末とした。この複合体粉末0.2gをドーナッツ状の容器内に入れて、ハンドプレス機により9800N(1Ton)の荷重をかけることにより、外径7mm、内径3mmのトロイダル形状の成形体を得た。この成形体について、ネットワーク・アナライザー(アジレント・テクノロジー社製;E5071C)と同軸型Sパラメーター法サンプルホルダーキット(関東電子応用開発社製;CSH2-APC7、試料寸法:φ7.0mm-φ3.04mm×5mm)を用い、0.1~4.5GHzにおける複素比透磁率の実数部μ’および虚数部μ”、並びに複素比誘電率の実数部ε’および虚数部ε”を測定し、複素比透磁率の損失係数tanδ(μ)=μ”/μ’および複素比誘電率の損失係数tanδ(ε)=ε”/ε’を求めた。表4中に、1GHz、2GHzおよび3GHzにおけるこれらの結果を例示する。
途中添加の仕込みCo/Feモル比を0.15(実施例2)および0.20(実施例3)にそれぞれ増量したことを除き、実施例1と同様の条件で実験を行った。製造条件および結果を実施例1と同様に表1~表4に示す(以下の各例において同じ)。
前駆体を成長させる際、Co途中添加後の空気吹き込み速度を81.5mL/minに低下させたことを除き、実施例2と同様の条件で実験を行った。
前駆体を成長させる際、Co途中添加後の空気吹き込み速度を40.8mL/minに低下させたことを除き、実施例3と同様の条件で実験を行った。
途中添加の仕込みCo/Feモル比を0.25に増量したことを除き、実施例5と同様の条件で実験を行った。
初期段階の仕込みCo/Feモル比を0.15に増量し、途中添加の仕込みCo/Feモル比を0.15に減量したことを除き、実施例5と同様の条件で実験を行った。
安定化処理後に、再度、同じ炉中で還元処理および安定化処理を1回実施したことを除き、実施例4と同様の条件で実験を行った。この場合、2回目の還元処理および安定化処理の条件は、それぞれ1回目の還元処理および安定化処理の条件と同様とした(以下の実施例9、10において同じ)。
安定化処理後に、再度、同じ炉中で還元処理および安定化処理を1回実施したことを除き、実施例5と同様の条件で実験を行った。
安定化処理後に、再度、同じ炉中で還元処理および安定化処理を1回実施したことを除き、実施例6と同様の条件で実験を行った。
安定化処理の温度を70℃に変更したことを除き、実施例9と同様の条件で実験を行った。
安定化処理の温度を70℃に変更したことを除き、実施例10と同様の条件で実験を行った。
前駆体を成長させる際、Co途中添加後の空気吹き込み速度を34.6mL/minに低下させたことを除き、実施例12と同様の条件で実験を行った。
前駆体形成過程において、オキシ水酸化鉄の核晶を生成させた後の液温を50℃とし、反応元液中に存在していた全Fe2+の40%が酸化するまでに液中に通気した空気の吹き込み速度を106mL/minとしたことを除き、実施例13と同様の条件で実験を行った。
初期段階の仕込みCo/Feモル比を0.08とし、途中添加の仕込みCo/Feモル比を0.27としたことを除き、実施例14と同様の条件で実験を行った。
初期段階の仕込みCo/Feモル比を0.08とし、途中添加の仕込みCo/Feモル比を0.27としたこと、および前駆体形成過程において、Co途中添加後、酸化が完結するまでの空気吹き込み中の液温を60℃から55℃に変えたことを除き、実施例13と同様の条件で実験を行った。
比較例1、2、3、4および5では、初期段階の仕込みCo/Feモル比をそれぞれ0.05、0.10、0.15、0.20および0.25とし、かつCoの途中添加を行わなかったことを除き、いずれも実施例1と同様の条件で実験を行った。
Claims (17)
- 平均粒子径100nm以下のFe-Co合金粉末であって、保磁力Hcが52.0~78.0kA/m、飽和磁化σsが160Am2/kg以上であるFe-Co合金粉末。
- 飽和磁化σs(Am2/kg)がCo/Feモル比との関係において下記(1)式を満たす請求項1に記載のFe-Co合金粉末。
σs≧50[Co/Fe]+151 …(1)
ここで、[Co/Fe]は粉体の化学組成におけるCoとFeのモル比を意味する。 - Co/Feモル比が0.15~0.50である請求項1または2に記載のFe-Co合金粉末。
- 粉末を構成する粒子の平均軸比(=平均長径/平均短径)が1.40より大きく1.70未満である請求項1~3のいずれか1項に記載のFe-Co合金粉末。
- JIS K6911に準拠した二重リング電極方法により、金属粉末1.0gを電極間に挟んで25MPa(8kN)の垂直荷重を付与しながら印加電圧10Vにて測定した場合の体積抵抗率が1.0×108Ω・cm以上である請求項1~4のいずれか1項に記載のFe-Co合金粉末。
- 当該粉末とエポキシ樹脂を90:10の質量割合で混合して作製した成形体を磁気測定に供したとき、1GHzにおいて、複素比透磁率の実数部μ’が2.50以上、かつ複素比透磁率の損失係数tanδ(μ)が0.05未満となる性質を有する請求項1~5のいずれか1項に記載のFe-Co合金粉末。
- 当該粉末とエポキシ樹脂を90:10の質量割合で混合して作製した成形体を磁気測定に供したとき、2GHzにおいて、複素比透磁率の実数部μ’が2.80以上、かつ複素比透磁率の損失係数tanδ(μ)が0.12未満となる性質を有する請求項1~6のいずれか1項に記載のFe-Co合金粉末。
- 当該粉末とエポキシ樹脂を90:10の質量割合で混合して作製した成形体を磁気測定に供したとき、3GHzにおいて、複素比透磁率の実数部μ’が3.00以上、かつ複素比透磁率の損失係数tanδ(μ)が0.30未満となる性質を有する請求項1~7のいずれか1項に記載のFe-Co合金粉末。
- FeイオンおよびCoイオンを含む水溶液に酸化剤を導入して核晶を生成させ、FeおよびCoを成分に持つ前駆体を析出成長させるに際し、析出反応に使用する全Co量の40%以上に相当する量のCoを核晶生成開始後かつ析出反応終了前の時期に前記水溶液中に添加して前駆体を得る工程(前駆体形成工程)、
前駆体の乾燥物を還元性ガス雰囲気中で250~650℃に加熱することにより、Fe-Co合金相を持つ金属粉末を得る工程(還元工程)、
還元後の金属粉末粒子の表層部に酸化保護層を形成する工程(安定化工程)、
を有するFe-Co合金粉末の製造方法。 - 前駆体形成工程において、析出反応に使用する全Co量を、Co/Feモル比0.15~0.50の範囲とする請求項9に記載のFe-Co合金粉末の製造方法。
- 前駆体形成工程において、希土類元素(Yも希土類元素として扱う)が水溶液中に存在している状態で前記核晶を生成させる請求項9または10に記載のFe-Co合金粉末の製造方法。
- 前駆体形成工程において、希土類元素(Yも希土類元素として扱う)、Al、Si、Mgの1種以上が水溶液中に存在している状態で前記析出成長を進行させる請求項9~11のいずれか1項に記載のFe-Co合金粉末の製造方法。
- 前記安定化工程後に、還元性ガス雰囲気中での250~650℃の加熱処理と、それに続く前記安定化工程の処理を1回以上実施する工程(還元・安定化反復工程)、
を有する請求項9~12のいずれか1項に記載のFe-Co合金粉末の製造方法。 - 請求項1~8のいずれか1項に記載のFe-Co合金粉末を使用して形成されたアンテナ。
- 請求項1~8のいずれか1項に記載のFe-Co合金粉末を樹脂組成物と混合した成形体を構成部材に有する周波数430MHz以上の電波を受信、送信、または送受信するアンテナ。
- 請求項1~8のいずれか1項に記載のFe-Co合金粉末を使用して形成されたインダクタ。
- 請求項1~8のいずれか1項に記載のFe-Co合金粉末を使用して形成されたEMIフィルタ。
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US20080055178A1 (en) * | 2006-09-04 | 2008-03-06 | Samsung Electro-Mechanics Co., Ltd. | Broad band antenna |
JP5177542B2 (ja) | 2008-10-27 | 2013-04-03 | 国立大学法人東北大学 | 複合磁性体、それを用いた回路基板、及びそれを用いた電子部品 |
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EP3127634A4 (en) | 2018-01-31 |
TWI675114B (zh) | 2019-10-21 |
KR102290573B1 (ko) | 2021-08-19 |
KR20160140777A (ko) | 2016-12-07 |
US20180169752A1 (en) | 2018-06-21 |
CN106163700A (zh) | 2016-11-23 |
JP2019085648A (ja) | 2019-06-06 |
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EP3127634A1 (en) | 2017-02-08 |
TW201542838A (zh) | 2015-11-16 |
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