CN113534027B - Magnetization testing method and method for preparing soft magnetic ferrite by using same - Google Patents
Magnetization testing method and method for preparing soft magnetic ferrite by using same Download PDFInfo
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- CN113534027B CN113534027B CN202110860176.4A CN202110860176A CN113534027B CN 113534027 B CN113534027 B CN 113534027B CN 202110860176 A CN202110860176 A CN 202110860176A CN 113534027 B CN113534027 B CN 113534027B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/12—Measuring magnetic properties of articles or specimens of solids or fluids
- G01R33/16—Measuring susceptibility
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- C—CHEMISTRY; METALLURGY
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
- C04B35/62605—Treating the starting powders individually or as mixtures
- C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
- H01F1/342—Oxides
- H01F1/344—Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3262—Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
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- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
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Abstract
The invention discloses a magnetization testing method and a method for preparing soft magnetic ferrite by using the same, belonging to the technical field of magnetic material preparation. According to the invention, the weight and the volume of the test powder can be ensured to be fixed through the specific annular material box, and the sample meets the standard and unified sample preparation requirement, so that the stability and the repeatability of the subsequent detection result are ensured, the stable and reliable detection result is ensured, more accurate detection data is obtained, the inductance L is obtained through the closed magnetic circuit test of the annular sample inductance test jig, the magnetic conductivity data of the pre-sintered magnetic performance of the reaction powder is directly obtained through formula calculation, the pre-sintered solid phase reaction result is more accurate and visual, and the method is more standardized and is suitable for the wide transverse comparison of the magnetization degree of the pre-sintered material. The measurement result of the presintering magnetization degree is directly related to the final performance parameter magnetic permeability of the soft magnetic ferrite core, and the method can be applied to monitoring and adjusting the presintering effect to obtain the soft magnetic ferrite core of the sintering final product meeting the requirements.
Description
Technical Field
The invention relates to the technical field of magnetic material preparation, in particular to a magnetization testing method and a method for preparing soft magnetic ferrite by using the same.
Background
Soft magnetic ferrite is one of the most used types of soft magnetic materials. The soft magnetic ferrite has the characteristics of high magnetic permeability, higher use frequency, lower loss and the like, and the magnetic core prepared from the soft magnetic ferrite is widely applied to the fields of various switching power transformers, common mode inductances, EMI filters and the like. The soft magnetic ferrite core is made from powdered soft magnetic ferrite particles through the procedures of molding, sintering, post-processing and the like. The soft magnetic ferrite particles are generally prepared from metal oxides such as iron oxide, zinc oxide, manganous oxide and the like serving as raw materials through the working procedures of proportioning, raw material mixing, presintering, pulping, slurry grinding, spray granulation and the like. Since the soft ferrite core undergoes a solid phase reaction during sintering, the volume thereof is contracted. If the shrinkage ratio is too large, product defects such as sintering cracking, deformation and the like may be caused. In order to reduce the shrinkage rate in the sintering process and improve the production stability and quality of the product, the method is generally solved by adding a pre-sintering process in the production process of the soft magnetic ferrite particles. The presintering is to sinter the proportioned and mixed raw materials at a certain temperature, the presintering temperature is generally lower than the final sintering temperature of the materials, and the raw materials can initially undergo solid-phase reaction at a lower temperature, but the reaction degree is lower, so that the shrinkage ratio of the magnetic core sintering process is reduced to a certain extent. If the solid phase reaction degree in the presintering process is higher, the reactivity is reduced when the magnetic core is sintered, and the achievement of the electromagnetic performance of the finished magnetic core product is not facilitated. If the reaction degree is low, the purpose of reducing the sintering shrinkage ratio of the magnetic core cannot be well achieved. In order to monitor the solid phase reaction degree of the burn-in process, the setting and adjustment of the burn-in process parameters are guided, and the magnetization degree is generally selected as the monitoring parameter in the industry.
The magnetization test at present is to put the powder after pre-sintering into a specific cup-shaped container, scrape the excessive powder beyond the plane of the cup mouth by a ruler-shaped tool after the container is filled, wind a winding with a specific number of turns outside the container, record the inductance of the winding on the container filled with the powder to be tested as L1 when the winding is connected with an LCR tester, record the inductance of the winding as L0 when the powder is not filled, and the magnetization= (L1/L0-1) is 100%, and the test method is shown in figure 1. Another method for measuring the magnetization degree is to fill a cylindrical plastic container with a specific volume with soft ferrite pre-sintered powder, weigh the soft ferrite pre-sintered powder with an electronic scale to be W0, and then place a magnet at a specific height above the electronic scale, wherein the weight reading is W1, and can be calculated according to the following formula: magnetization x= (W0-W1)/W0.
However, the magnetization measured in the above two modes is proportional data, and the degree of the pre-firing solid phase reaction can be determined only by comparison of the lateral values. However, the data cannot be widely compared and referenced because the size of the test container, the winding structure, the magnetism of the magnet, etc. are different among different manufacturers. Meanwhile, the parameter is not directly related to the final performance parameter magnetic permeability of the soft magnetic ferrite core, and the sintering performance of the final product cannot be indirectly controlled through the judgment result of the presintering degree. Meanwhile, the definition of magnetization degree is lack of standardization as can be seen by the different methods, and although the degree of presintering solid phase reaction can be reflected, the test method and the test result cannot be compared. In the first test method, the volume of the powder filled into the container is fixed, but the filling effect of the powder is different from one powder to another, that is, the density of the powder is different, so that the same volume is possible, the weight is different, and the setting difference of the test results is caused, so that the analysis and the judgment are affected. The above problems with the determination method of burn-in magnetization have prevented standardization and specialization of the burn-in process control method.
The CN107450038A is a device for measuring the magnetization of the soft ferrite pre-sintering material, and discloses a device for measuring the magnetization of the soft ferrite pre-sintering material, which comprises a weighing mechanism, a support arranged above the weighing mechanism and a support piece arranged at the upper end of the support, wherein a permanent magnet is arranged on the support piece, a container for containing the soft ferrite pre-sintering material is arranged on the weighing mechanism connected with the inside of the support, and the support, the support piece and the container are of non-magnetic structures. The disclosed device for measuring the magnetization degree of the soft magnetic ferrite pre-sintering material adopts a second electronic scale weighing method, and the measured individual difference exists, so that the measured individual difference cannot be directly compared, the parameter and the final performance parameter magnetic permeability of the soft magnetic ferrite core are not directly related, and the sintering performance of the final product cannot be indirectly controlled through the judgment result of the pre-sintering degree.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings that the existing method for measuring the magnetization degree of the soft magnetic ferrite pre-sintering material has obvious measurement method difference, the parameters cannot be directly compared, the magnetic permeability of the final performance parameters of the soft magnetic ferrite core is not directly related, and the sintering performance of the final product cannot be indirectly controlled, and provides a method for testing the magnetization degree of the soft magnetic ferrite pre-sintering material.
Still another object of the present invention is to provide a method for preparing the soft magnetic ferrite.
The above object of the present invention is achieved by the following technical scheme:
a magnetization testing method, comprising the steps of:
s1, preparing a presintering material sample: weighing the presintered material powder to be measured with the set weight, filling the presintered material powder into an annular material box with the set volume, and preparing an annular presintered material sample with the set density;
s2, performing closed magnetic circuit inductance test on the annular pre-sintered material sample to obtain inductance L of the annular pre-sintered material sample;
s3, calculating the magnetic permeability of the annular pre-sintered material sample according to the inductance L, recording as mu 1, recording the standard magnetic permeability of the soft magnetic ferrite as mu 2, and then the magnetization = mu 2/mu 1 x 100%,
wherein the density of the annular pre-sintered material sample is 1.1-2.2 g/cm 3 。
In the existing method for measuring the magnetization degree of the solid phase reaction degree in the presintering process, the sample preparation difference is large, redundant components are scraped after the sample is filled, filling effects of different powders are different, namely the densities of the powders are different, the weights of the presintering materials with the same volume are different, and further, the test results are different, so that analysis and judgment are affected.
According to the preparation method of the annular pre-sintering material sample, the weight of the pre-sintering material powder to be detected is accurately weighed, the volume of the material box is fixed, the weight and the volume can be accurately controlled, the density stability of the annular pre-sintering material sample is ensured, the sample preparation density is stable and repeatable, and the stability and reliability of the subsequent detection result are further ensured.
The sample weight is accurately weighed, the sample volume is pressed through a specific material box, and compared with the existing filling scraping (the volume and the weight are not quantitatively controlled), the method has scientific controllability, stable data and can be transversely compared.
On the other hand, the existing measurement of the pre-sintering magnetization is a relative magnetization value, only a relative proportion is adopted, the definition of the magnetization is different, the permeability of the pre-sintering material cannot be embodied, and the magnetization is not transversely comparable with other detection methods. According to the magnetization testing method, the inductance L of the annular presintering material sample with fixed density and weight is measured through the closed magnetic circuit inductance test, specific magnetic conductivity performance can be obtained through calculation, the magnetization degree of the standard magnetic conductivity of the relative soft magnetic ferrite material is obtained, stability of a detection result is achieved, physical and chemical properties of the presintering material such as magnetic conductivity and magnetization degree can be directly and objectively reflected, the properties are independent of the detection method, the magnetic conductivity testing method is independent and reliable, the magnetic conductivity testing method can be transversely compared with other detection results, and the magnetic conductivity testing method can be further applied to monitoring and adjusting of presintering effects, and a soft magnetic ferrite core which is a sintering final product meeting requirements is obtained, and the magnetic conductivity of the final performance parameter of the soft magnetic ferrite core is directly related.
Compared with the prior art that the magnetization can be defined only by measuring the non-closed-loop inductance, the method provided by the invention has the advantages that the inductance is measured through a closed loop, and then the specific magnetic conductivity is obtained through calculation, so that the magnetization is finally obtained.
The closed loop measurement inductance value, the closed magnetic circuit can test the magnetic conductivity, the magnetic conductivity is only related to the self magnetic property of the powder under the condition of the same filling effect of the powder, and is irrelevant to the test method, while the inductance value tested by the open circuit test adopted in the prior art is a relative value, the correlation proportion of the inductance value and the self magnetic property of the material is related to the test method, and the inductance values obtained under different test conditions and the magnetization degree calculated by the inductance values cannot be directly compared and judged.
The closed magnetic circuit test can reflect the original magnetic property of the powder, is convenient for comparing the standard magnetic permeability of the target with the magnetic permeability gap of the powder, and can directly feed back the presintering degree because the gap (proportional relation) is irrelevant to the test method.
Further preferably, the density of the pre-sintered material sample is 1.3-1.8 g/cm 3 。
Further preferably, the density of the pre-sintered material sample is 1.3-1.5 g/cm 3 。
The density influences the measurement result of the related inductance L, the larger the density and the larger the weight of the powder with the same volume, the higher the L when the test conditions are the same, and the accuracy of the test result is influenced.
Preferably, the annular pre-sintered material sample in S1 is prepared by the following method:
and loading the powder of the presintered material to be measured into an annular non-magnetic material box, pressing the material box cover into the material box filled with the powder, and enabling the upper plane of the material box to be flush with the upper plane of the material box cover to prepare the presintered material sample.
According to the preparation method, the annular pre-sintered material sample is prepared by adopting the specific material box of S1, and because the powder has certain compressibility, the powder can be uniformly filled in a fixed volume formed by the material box cover and the material box through the height difference of the material box and the material box cover, the weight is fixed, and the density of the prepared annular pre-sintered material sample is determined, and the annular pre-sintered material sample is stable and repeatable, so that the stability and reliability of a subsequent detection result are ensured.
Preferably, the ratio Do/Di of the outer diameter to the inner diameter of the annular pre-sintered material sample is less than or equal to 1.4.
The inner diameter and the outer diameter of the annular presintering material sample are corresponding to the outer diameter and the inner diameter of the annular material box, the difference between the inner diameter and the outer diameter is too large, the inner diameter and the outer diameter of the magnetic field are uneven, and the testing accuracy is affected.
Further preferably, the outer diameter Do of the annular presintering material sample (namely the space in the cavity of the material box) is less than or equal to 100mm, the inner diameter Di is more than or equal to 10mm, and the filling height h is less than or equal to 50mm.
The following are to be described:
the pre-sintered material sample prepared by the method is an annular sample, and if the inner diameter of the pre-sintered material sample is too small, the design and arrangement of internal test contacts are problematic, and the test pins and the contacts are not arranged in enough space; too large an outer diameter, too much powder is needed and the test is inconvenient; the test needle is too long when the height of the pre-sintered material sample is too high, the strength and the stability are poor, and the accuracy of the detection result is affected.
Wherein, further description is:
the thickness of the cover is set to h1, which is in the range of 1-10 mm, and mainly takes the strength problem of the cover when the cover is too thin and increases the friction resistance when the cover is too thick, thus being inconvenient to operate.
Powder weight m=d (Do-Di) pi 0.25 h '/1000, where d is powder density (after compression), h ' is height after compression, h ' =h-h 1, d ranges from 1.1 to 2.2g/cm 3 Preferably 1.6 to 1.8g/cm 3 . d is set in this range, mainly considering that the natural bulk density of the powder is 1 to 1.6g/cm 3 In order to ensure the consistency of the density of the filling powder, a mode of pressing by a pressing cover after fixing the weight is adopted, and if the required density is too large, the required pressing force is too large, so that the operation is inconvenient.
Further preferably, the outer diameter Do of the pre-sintering material sample is 40-100 mm, the inner diameter Di of the pre-sintering material sample is 30-72 mm, and the height h of the pre-sintering material sample is 15-45 mm.
Preferably, the weight of the pre-sintering powder to be measured is 10-300 g.
On the premise of setting the density of the annular pre-sintering material sample, excessive or insufficient weight of the pre-sintering material powder to be detected can cause that the overall size does not meet the detection requirement, thereby affecting the accuracy of the detection result.
Preferably, the winding turns N of the closed magnetic circuit test structure is 5-20 Ts. Too few turns, uneven magnetic field distribution and influence the test accuracy; the number of turns is too many, and test fixture preparation is complicated, and the magnetization magnetic flux is too little simultaneously, also influences the test accuracy.
Wherein, the magnetic permeability mu 1 of the annular presintering material sample can be calculated by the following method:
according toCalculating the magnetic permeability of the powder, marking as mu 1, marking the standard magnetic permeability of the finished powder product as mu 2, and then the magnetization degree=mu 2/mu 1 is 100%,
wherein N is the number of winding turns of the closed magnetic circuit test structure, do, di, h are the outer diameter, inner diameter and height of the pre-sintered material sample, h=h '-h1, respectively, wherein h1 is the thickness of the cover of the material box, and h' is the height of the powder before compression. Meanwhile, in the formula, L units are mu H, H, do and Di units are m, and the following is the same.
Preferably, the non-magnetic material box is prepared from plastic. The preparation material of the non-magnetic material box can be engineering plastics such as ABS, POM, PC, PVC, PTFE, PMMA, phenolic plastics (bakelite) and the like.
Further, PMMA (polymethyl methacrylate, an alias organic glass), POM (polyoxymethylene thermoplastic crystalline polymer), and the like may be preferable.
The nonmagnetic material box needs to have nonmagnetic property and certain mechanical strength, can well meet the performance by adopting the materials, and has good processing performance.
Preferably, the method for measuring the inductance of the closed magnetic circuit in S2 is as follows:
the test fixture pressure head of the annular sample inductance test fixture is pressed down, the probe on the upper test board is communicated with the contact on the lower test board, a closed magnetic circuit test structure with a spiral winding wound outside the annular sample is formed, the outgoing line on the lower test board of the test fixture is connected with the LCR, and the inductance L of the annular presintered material sample can be measured.
The closed loop measurement inductance value, the closed magnetic circuit can test the magnetic conductivity, the magnetic conductivity is only related to the intrinsic magnetic property of the powder under the condition of the same filling effect of the powder, and is irrelevant to the testing method, while the inductance value tested by the open circuit test adopted in the prior art is a relative value, the correlation proportion of the inductance value and the intrinsic magnetic property of the material is related to the testing method, and the inductance values obtained under different testing conditions and the magnetization degree calculated by the inductance values cannot be directly compared and judged.
The invention also specifically protects a preparation method of the soft magnetic ferrite, which comprises the steps of molding, presintering, sintering and post-processing, wherein the magnetization degree is monitored by adopting the magnetization degree test method in the presintering step, and then the feedback adjustment of presintering technological parameters is carried out.
The process for preparing the soft magnetic ferrite particles generally comprises the steps of batching, mixing, presintering, grinding, granulating and the like.
Wherein the ingredients are Fe 2 O 3 、ZnO、Mn 3 O 4 Weighing a plurality of oxide powders such as CuO, niO and the like according to a formula;
mixing is a process of uniformly mixing the mixture;
the pre-sintering means that the mixed powder which is uniformly mixed is roasted under a certain temperature and atmosphere, the roasting is to make the materials perform preliminary solid phase reaction, so that the reactivity of the soft magnetic ferrite particles in the final sintering process is reduced (after the soft magnetic ferrite particles are obtained, the final soft magnetic ferrite core is obtained through the processes of molding, sintering, grinding and the like, wherein the final sintering means the final sintering after molding);
grinding refers to the process of adding water and other additives into the presintered powder and crushing the powder to enable the particle size of the presintered powder to reach the expected size;
spray granulation is a process of removing moisture and the like from a slurry containing fine calcined powder after grinding and combining the same into macroparticles of a certain diameter.
The magnetization degree is measured after the burn-in process. Because the oxide can initially perform the solid-phase reaction during presintering, the degree of the initial solid-phase reaction has a great influence on the subsequent manufacturability and electromagnetic performance of the powder, and the presintering temperature, presintering time, atmosphere and the like influence the degree of the initial solid-phase reaction. The process parameters can be adjusted according to the result of the magnetization measurement in combination with the actual process parameters.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a magnetization testing method, which can ensure that the weight and the volume of testing powder are fixed through a specific annular material box sample preparation, and the sample meets the standard and unified sample preparation requirement, is stable and repeatable, thereby ensuring the stability and reliability of the subsequent detection result and obtaining more accurate detection data.
Further, the magnetization degree test method adopts the closed magnetic circuit test of the annular sample inductance test jig to obtain the inductance L, and directly obtains the magnetic permeability data of the pre-sintered magnetic performance of the reactive powder through formula calculation, so that the magnetization degree test method is more accurate and visual, more standardized, reflects the pre-sintered solid phase reaction result, and is suitable for wide transverse comparison of magnetization degrees of the pre-sintered materials.
The measurement result of the presintering magnetization degree is directly related to the final performance parameter magnetic permeability of the soft magnetic ferrite core, and the method can be applied to monitoring and adjusting the presintering effect to obtain the soft magnetic ferrite core of the sintering final product with composite requirements.
Drawings
Fig. 1 shows a prior art magnetization detecting device.
Fig. 2 is a schematic diagram of a cartridge structure according to the present invention, 1 is a cartridge cover, and 2 is a cartridge.
Fig. 3 is a cross-sectional view of a cartridge of the present invention.
Fig. 4 is a cross-sectional view of the cartridge after filling the pre-firing material, and fig. 3 is the pre-firing material.
Fig. 5 is a schematic structural diagram of the sample preparation of the pre-sintering material after completion of the preparation.
Fig. 6 is a cross-sectional view of the sample pre-sinter after preparation.
Fig. 7 is a schematic structural diagram of the inductance test fixture for the ring-shaped sample.
Fig. 8 is a diagram of the number of winding turns of the closed magnetic circuit test structure of the cartridge.
Fig. 9 is a vertical sectional view of the annular cartridge after loading, before capping and after capping.
Detailed Description
The invention will be further described with reference to the following specific embodiments, but the examples are not intended to limit the invention in any way. Raw materials reagents used in the examples of the present invention are conventionally purchased raw materials reagents unless otherwise specified.
Example 1
A magnetization testing method, comprising the steps of:
s1, preparing a presintering material sample: weighing pre-sintering material powder to be measured with set weight, loading the powder into an annular non-magnetic material box, pressing a material box cover into the material box filled with the powder, and enabling the upper plane of the material box to be level with the upper plane of the material box cover to prepare an annular pre-sintering material sample;
s2, placing the annular pre-sintered material sample into an annular sample inductance test jig for closed magnetic circuit inductance test, and measuring inductance L of the annular pre-sintered material sample;
s3, according toCalculating the magnetic permeability of the powder, marking as mu 1, marking the standard magnetic permeability of the finished powder product as mu 2, and then the magnetization degree=mu 2/mu 1 is 100%,
wherein N is the number of winding turns of the closed magnetic circuit test structure, and Do, di and h are respectively the outer diameter, the inner diameter and the height of the annular pre-sintered material sample.
The weight of the filled powder of the presintering material to be tested is 22g, the outer diameter of the annular presintering material sample is 50mm, the inner diameter of the annular presintering material sample is 36mm, the filling height of the annular presintering material sample is 20mm, the thickness of a material box cover is 3mm, and the number of turns N of a winding of the closed circuit magnetic circuit test structure is 10.
Wherein an annular cartridge and a cartridge cover are made of PMMA, the cartridge cover being able to be pressed into the cartridge from above the cartridge, as shown in fig. 2 and 3.
For example, for producing PC95 material (TDK soft magnetic ferrite material mark), the standard magnetic permeability is 3300.
In the sample preparation process, a certain weight of powder to be measured is measured according to a standard, and uniformly loaded into an annular material box, and the loaded material box is shown in fig. 4.
The lid is pressed into the powder-filled cartridge such that the upper plane of the cartridge is flush with the upper plane of the lid. Since the powder has certain compressibility, the thickness of the material box cover is reasonably set, so that the powder can be uniformly filled in a fixed volume formed by the material box cover and the material box, the weight is fixed, and a sample to be measured after the powder is filled is shown in fig. 5 and 6.
The annular magazine was placed into an annular sample inductance test fixture, such as the fixture shown in fig. 5 and 6. And pressing down the pressure head of the test fixture, connecting the probe on the upper test board with the contact on the lower test board, finally forming a closed magnetic circuit test structure with a spiral winding wound outside the annular sample, connecting the outgoing line on the lower test board of the test fixture with the LCR, and measuring the inductance L of the sample.
The inductance L obtained by the above measurement was 10. Mu.H.
According toThe magnetic permeability of the powder was calculated as 89.53, denoted μ 1, where l=10×10 - 6 H, n=10ts, h=20-3=17 mm, do=50 mm, di=36 mm, the standard permeability of the finished powder product is denoted μ2, μ2=3300, and the magnetization=μ2/μ1×100% = 89.53/3300×100%, and the calculated magnetization is 2.71%.
Example 2
A method for testing the magnetization of a soft ferrite pre-sinter (using the same pre-sinter as in example 1), comprising the steps of:
s1, preparing an annular presintering material sample: loading the powder of the presintered material to be measured with the standard weight into an annular non-magnetic material box, pressing a material box cover into the material box filled with the powder, and enabling the upper plane of the material box to be level with the upper plane of the material box cover to prepare an annular presintered material sample;
s2, placing the annular pre-sintered material sample into an annular sample inductance test jig for closed magnetic circuit inductance test, and measuring inductance L (shown in fig. 7 and 8) of the annular pre-sintered material sample;
s3, according toCalculating the magnetic permeability of the powder, marking as mu 1, marking the standard magnetic permeability of the finished powder product as mu 2, and then the magnetization degree=mu 2/mu 1 is 100%,
wherein N is the number of winding turns of the closed magnetic circuit test structure, and Do, di, h are the outer diameter, inner diameter and height of the annular pre-sintered material sample, respectively, as shown in fig. 9:
wherein the outer diameter of the presintering material is Do, the inner diameter is Di, and the filling height is h;
h=h '-h1, h' is the powder filling height before capping, h1 is the lid thickness.
The weight of the filled powder of the presintering material to be tested is 95.5g, the outer diameter of the annular presintering material sample is 70mm, the inner diameter of the annular presintering material sample is 50mm, the h' filling height is 40mm, the thickness of the material box cover is 3mm, and the number of turns N of the winding of the closed circuit magnetic circuit test structure is 15.
The annular material box is placed into an annular sample inductance test jig, a test fixture pressure head is pressed down, a probe on an upper test board is communicated with a contact on a lower test board, a closed magnetic circuit test structure with a spiral winding wound outside an annular sample is finally formed, an outgoing line on the lower test board of the test fixture is connected with an LCR, and the inductance L of the sample can be measured.
The inductance L obtained by the above measurement was 50.2. Mu.H.
According toThe magnetic permeability of the powder was calculated to be 89.61, denoted μ1, and the standard magnetic permeability of the powder product was denoted μ2, μ2=3300, and the magnetization = μ2/μ1×100%, calculated to be 2.72%.
Example 3
A magnetization testing method for a soft magnetic ferrite pre-sintered material (the standard magnetic permeability of the soft magnetic ferrite is 2300) comprises the following steps:
s1, preparing an annular presintering material sample: loading the powder of the presintered material to be measured with the standard weight into an annular non-magnetic material box, pressing a material box cover into the material box filled with the powder, and enabling the upper plane of the material box to be level with the upper plane of the material box cover to prepare an annular presintered material sample;
s2, placing the annular pre-sintered material sample into an annular sample inductance test jig for closed magnetic circuit inductance test, and measuring inductance L of the annular pre-sintered material sample;
s3, according toCalculating the magnetic permeability of the powder, marking as mu 1, marking the standard magnetic permeability of the finished powder product as mu 2, and then the magnetization degree=mu 2/mu 1 is 100%,
wherein N is the number of winding turns of the closed magnetic circuit test structure, and Do, di and h are respectively the outer diameter, the inner diameter and the height of the annular pre-sintered material sample.
The weight of the filled powder of the presintering material to be tested is 12g, the outer diameter of the annular presintering material sample is 40mm, the inner diameter of the annular presintering material sample is 30mm, the filling height of the annular presintering material sample is 20mm, the thickness of a material box cover is 5mm, and the number of turns N of a winding of the closed circuit magnetic circuit test structure is 15.
The annular material box is placed into an annular sample inductance test jig, a test fixture pressure head is pressed down, a probe on an upper test board is communicated with a contact on a lower test board, a closed magnetic circuit test structure with a spiral winding wound outside an annular sample is finally formed, an outgoing line on the lower test board of the test fixture is connected with an LCR, and the inductance L of the sample can be measured.
The inductance L obtained by the above measurement was 12.3. Mu.H.
According toThe magnetic permeability of the powder was calculated as 63.34, denoted as μ1, and the standard magnetic permeability of the powder product was denoted as μ2, μ2=2300, the magnetization = μ2/μ1×100% and the magnetization was calculated as 2.75%.
Example 4
A method for testing the magnetization of a soft ferrite pre-sinter (using the same pre-sinter as in example 3), comprising the steps of:
s1, preparing an annular presintering material sample: loading the powder of the presintered material to be measured with the standard weight into an annular non-magnetic material box, pressing a material box cover into the material box filled with the powder, and enabling the upper plane of the material box to be level with the upper plane of the material box cover to prepare an annular presintered material sample;
s2, placing the annular pre-sintered material sample into an annular sample inductance test jig for closed magnetic circuit inductance test, and measuring inductance L of the annular pre-sintered material sample;
s3, according toCalculating magnetic permeability of powder, recording as mu 1, and making powder productThe standard permeability is noted as mu 2, the magnetization = mu 2/mu 1 x 100%,
wherein N is the number of winding turns of the closed magnetic circuit test structure, and Do, di and h are respectively the outer diameter, the inner diameter and the height of the annular pre-sintered material sample.
The weight of the filled powder of the presintering material to be tested is 12g, the outer diameter of the annular presintering material sample is 40mm, the inner diameter of the annular presintering material sample is 20mm, the filling height of the annular presintering material sample is 20mm, the thickness of a material box cover is 5mm, and the number of turns N of a winding of the closed circuit magnetic circuit test structure is 15.
The annular material box is placed into an annular sample inductance test jig, a test fixture pressure head is pressed down, a probe on an upper test board is communicated with a contact on a lower test board, a closed magnetic circuit test structure with a spiral winding wound outside an annular sample is finally formed, an outgoing line on the lower test board of the test fixture is connected with an LCR, and the inductance L of the sample can be measured.
The inductance L obtained by the above measurement was 28. Mu.H.
According toThe magnetic permeability of the powder was calculated as 59.85, denoted as μ1, and the standard magnetic permeability of the powder product was denoted as μ2, μ2=2300, the magnetization = μ2/μ1×100% and the magnetization was calculated as 2.60%.
Example 5
A magnetization testing method for a soft magnetic ferrite pre-sintered material (the standard magnetic permeability of the soft magnetic ferrite is 5000) comprises the following steps:
s1, preparing an annular presintering material sample: loading the powder of the presintered material to be measured with the standard weight into an annular non-magnetic material box, pressing a material box cover into the material box filled with the powder, and enabling the upper plane of the material box to be level with the upper plane of the material box cover to prepare an annular presintered material sample;
s2, placing the annular pre-sintered material sample into an annular sample inductance test jig for closed magnetic circuit inductance test, and measuring inductance L of the annular pre-sintered material sample;
s3, according toCalculating the magnetic permeability of the powder, marking as mu 1, marking the standard magnetic permeability of the finished powder product as mu 2, and then the magnetization degree=mu 2/mu 1 is 100%,
wherein N is the number of winding turns of the closed magnetic circuit test structure, and Do, di and h are respectively the outer diameter, the inner diameter and the height of the annular pre-sintered material sample.
The weight of the filled powder of the presintering material to be tested is 280g, the outer diameter of the annular presintering material sample is 100mm, the inner diameter of the annular presintering material sample is 72mm, the filling height of the annular presintering material sample is 50mm, the thickness of a material box cover is 5mm, and the number of turns N of a winding of the closed circuit magnetic circuit test structure is 20.
The annular material box is placed into an annular sample inductance test jig, a test fixture pressure head is pressed down, a probe on an upper test board is communicated with a contact on a lower test board, a closed magnetic circuit test structure with a spiral winding wound outside an annular sample is finally formed, an outgoing line on the lower test board of the test fixture is connected with an LCR, and the inductance L of the sample can be measured.
The inductance L obtained by the above measurement was 155. Mu.H.
According toThe magnetic permeability of the powder was calculated as 131.07, denoted as μ1, the standard magnetic permeability of the powder product was denoted as μ2, μ2=5000, and the magnetization = μ2/μ1×100%, calculated as 2.62%.
Example 6
A method for testing the magnetization of a soft ferrite pre-sinter (using the same pre-sinter as in example 5), comprising the steps of:
s1, preparing an annular presintering material sample: loading the powder of the presintered material to be measured with the standard weight into an annular non-magnetic material box, pressing a material box cover into the material box filled with the powder, and enabling the upper plane of the material box to be level with the upper plane of the material box cover to prepare an annular presintered material sample;
s2, placing the annular pre-sintered material sample into an annular sample inductance test jig for closed magnetic circuit inductance test, and measuring inductance L of the annular pre-sintered material sample;
s3, according toCalculating the magnetic permeability of the powder, marking as mu 1, marking the standard magnetic permeability of the finished powder product as mu 2, and then the magnetization degree=mu 2/mu 1 is 100%,
wherein N is the number of winding turns of the closed magnetic circuit test structure, and Do, di and h are respectively the outer diameter, the inner diameter and the height of the annular pre-sintered material sample.
The weight of the filled powder of the presintering material to be tested is 300g, the outer diameter of the annular presintering material sample is 100mm, the inner diameter of the annular presintering material sample is 72mm, the filling height of the annular presintering material sample is 50mm, the thickness of a material box cover is 5mm, and the number of turns N of a winding of the closed circuit magnetic circuit test structure is 20.
The annular material box is placed into an annular sample inductance test jig, a test fixture pressure head is pressed down, a probe on an upper test board is communicated with a contact on a lower test board, a closed magnetic circuit test structure with a spiral winding wound outside an annular sample is finally formed, an outgoing line on the lower test board of the test fixture is connected with an LCR, and the inductance L of the sample can be measured.
The inductance L obtained by the above measurement was 165. Mu.H.
According toThe magnetic permeability of the powder was calculated as 139.52, denoted as μ1, the standard magnetic permeability of the powder product was denoted as μ2, μ2=5000, and the magnetization = μ2/μ1×100% was calculated to give a magnetization of 2.79%.
The specific test results of examples 1 to 6 are shown in Table 1.
TABLE 1
Examples 1 and 2 are similar pre-sintered powders tested with different test ring sizes, and the same density is designed, and from the test results, the magnetization degree is basically the same, which reflects that the test results are basically the same under different test conditions (number of turns, ring shape, etc.) when the density is the same under the same control density, and the test results are basically the same, and the density of the test sample is controllable, so that the test results are stable.
Examples 3 and 4 were tested with the same pre-sintered powder, but example 4 used a ring with an outside diameter to inside diameter ratio of 2, exceeding 1.4. When this ratio is too large, the powder is not easily filled uniformly in the ring, and the test data are easily deviated due to different uniformity. Although the densities are the same, the density is a macroscopic average effect, the local non-uniformity causes data deviation, and the stability of the test result is affected, which indicates that the stability and the accuracy of the magnetization measurement of the soft magnetic ferrite pre-sintering material can be further improved by controlling the ratio Do/Di of the outer diameter to the inner diameter of the annular pre-sintering material sample to be less than or equal to 1.4.
As can be seen from examples 5 and 6, the design density values of the annular presintered material samples are different for the same external dimension standard samples, and the test data are obviously different, so that the detection method has high sensitivity.
From the detection results of examples 1 and 2, the detection method of the invention can effectively control the sample density, and further achieve the accurate stability of the final detection result through the stable control of the sample density. In examples 5 and 6, although the same submitted cartridge was used to prepare the sample, the density of the sample was not effectively controlled, and the final magnetization detection result also had a certain deviation, which indicates that the detection method of the present invention has high sensitivity, the stability and reliability of the detection result also decreased when the density of the sample was changed, and the stable control of the density of the sample was critical to the accurate stability of the final detection result.
Example 7
The preparation method of the soft magnetic ferrite comprises the steps of molding, presintering, sintering and post-processing, wherein the magnetization degree monitoring is carried out by adopting the magnetization degree testing method in the presintering step, and then the feedback adjustment of presintering technological parameters is carried out.
The process of preparing the soft magnetic ferrite particles is generally divided into the steps of batching, mixing, presintering, grinding and spray granulation.
Wherein the ingredients are Fe 2 O 3 、ZnO、Mn 3 O 4 Oxidation of CuO, niO, etcWeighing several of the powder according to a formula;
mixing is a process of uniformly mixing the mixture;
the pre-sintering means that the mixed powder which is uniformly mixed is roasted under a certain temperature and atmosphere, the roasting is to make the materials perform preliminary solid phase reaction, so that the reactivity of the soft magnetic ferrite particles in the final sintering process is reduced (after the soft magnetic ferrite particles are obtained, the final soft magnetic ferrite core is obtained through the processes of molding, sintering, grinding and the like, wherein the final sintering means the final sintering after molding);
grinding refers to the process of adding water and other additives into the presintered powder and crushing the powder to enable the particle size of the presintered powder to reach the expected size;
spray granulation is a process of removing moisture and the like from a slurry containing fine calcined powder after grinding and combining the same into macroparticles of a certain diameter.
The magnetization degree is measured after the burn-in process. Because the oxide can initially perform the solid-phase reaction during presintering, the degree of the initial solid-phase reaction has a great influence on the subsequent manufacturability and electromagnetic performance of the powder, and the presintering temperature, presintering time, atmosphere and the like influence the degree of the initial solid-phase reaction. The parameters of the presintering process can be adjusted according to the result of the magnetization measurement in combination with the actual process.
Comparative example 1
The standard magnetic permeability of the existing PC95 material (TDK soft magnetic ferrite material mark) is 3300. The magnetization degree of the presintering process is measured by adopting a traditional method, and the specific method is as follows:
the standard magnetic permeability of the existing PC95 material (TDK soft magnetic ferrite material mark) is 3300. The magnetization degree of the presintering process is measured by adopting a traditional method, and the specific method is as follows:
the jig used by company a, the measuring cup had a volume of 500ml and a height of 150mm, the pre-sintered powder was naturally filled therein, the cup mouth was scraped off, the inductance when the powder was filled was 30 μh, the air core inductance when not filled was 5 μh, the magnetization was (30/20-1) ×100% =16.67%, comparative example 2
The standard magnetic permeability of the existing PC95 material (TDK soft magnetic ferrite material mark) is 3300. The magnetization degree of the presintering process is measured by adopting a traditional method, and the specific method is as follows:
the same practical properties of the pre-sintered powder were measured by company B using a measuring cup having a volume of 1000ml and a height of 200mm in the same manner, but with a hollow inductance of 30. Mu.H and an inductance of 198. Mu.H when the powder was filled, the magnetization was 15.15%.
As can be seen from comparative example 1 and comparative example 2, since the jigs used by two companies A, B are different, the inductance test is related to the magnetic circuit, the number of turns of windings, the size, etc. of the test and the number of magnetic substances, and the magnetic substances with the same performance have different magnetization test data when the above conditions are different, and cannot be compared laterally, for example, the test results are 16.67% and 15.15% respectively for the same materials with different jigs, and the test results have a large difference and do not have the test stability and repeatability.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (9)
1. The magnetization testing method is characterized by comprising the following steps of:
s1, preparing a presintering material sample: weighing the presintered material powder to be measured with the set weight, filling the presintered material powder into an annular material box with the set volume, and preparing an annular presintered material sample with the set density;
s2, performing closed magnetic circuit inductance test on the annular pre-sintered material sample to obtain inductance L of the annular pre-sintered material sample;
s3, calculating the magnetic permeability of the annular pre-sintered material sample according to the inductance L, recording as mu 1, recording the standard magnetic permeability of the soft magnetic ferrite as mu 2, and then the magnetization = mu 2/mu 1 x 100%,
wherein the density of the annular pre-sintered material sample is 1.1-2.2 g/cm 3 ,
The ratio Do/Di of the outer diameter to the inner diameter of the annular pre-sintering material sample is less than or equal to 1.4.
2. The method of claim 1, wherein the annular pre-sinter sample has a density of 1.3 to 1.8g/cm 3 。
3. The method of claim 1, wherein the annular pre-sintered material sample has an outer diameter Do not greater than 100mm, an inner diameter Di not less than 10mm, and a height h not greater than 50mm.
4. A magnetization testing method according to claim 3, wherein the annular pre-sintered material sample has an outer diameter Do of 40 to 100mm, an inner diameter Di of 30 to 72mm, and a height h of 15 to 45mm.
5. The method of claim 4, wherein the pre-sinter powder to be tested has a weight of 10 to 300g.
6. The magnetization testing method according to claim 1, wherein the number of winding turns N of the closed magnetic circuit electrical sensing is 5 to 20Ts.
7. The magnetization testing method according to any one of claims 1 to 6, wherein the annular cartridge is made of plastic.
8. The magnetization testing method according to any one of claims 1 to 6, wherein the method for measuring the closed magnetic circuit inductance in S2 is as follows:
the test fixture pressure head of the annular sample inductance test fixture is pressed down, the probe on the upper test board is communicated with the contact on the lower test board, a closed magnetic circuit test structure with a spiral winding wound outside the annular sample is formed, the outgoing line on the lower test board of the test fixture is connected with the LCR, and the inductance L of the annular presintered material sample can be measured.
9. The method for preparing the soft magnetic ferrite comprises the working procedures of molding, presintering, sintering and post-processing, and is characterized in that the magnetization degree is monitored by adopting the magnetization degree testing method according to any one of claims 1-6 in the presintering working procedure, and the feedback adjustment of presintering technological parameters is further carried out.
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