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Soft magnetic nanocrystalline metal or alloy sheet-shaped particles with internal grain orientation and microwave absorbing material

A technology of grain orientation and flake particles, applied in the direction of magnetic materials, magnetic objects, magnetic field/electric field shielding, etc., can solve the limitation of low-frequency magnetic permeability value of magnetic permeability value, decrease of magnetic substance content and magnetic properties, and easy pollution. Absorbers and other issues, to achieve the effect of improving magnetic loss, improving low-frequency and broadband absorption performance, and broad application prospects

Inactive Publication Date: 2020-04-10
WUHAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

There are two main problems in the preparation process of the above-mentioned methods for obtaining grain-oriented particles. First, they adopt the method of dry grinding. Compared with the wet grinding method, the flaky degree of the obtained absorbent is affected Therefore, the magnetic permeability value closely related to the degree of flaking, especially the low-frequency magnetic permeability value, is also greatly limited; second, graphite is not easy to separate during the separation process of the absorbent, and it is easy to contaminate the absorbent and cause its magnetic substance The content and magnetic properties of the material will decrease; the addition of Cu and other grain orientation promoting elements will also reduce the magnetic properties of the material
In the existing reports and published technologies, no similar grain orientation effect has been found in the preparation of sheet-shaped absorbents by wet grinding.

Method used

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  • Soft magnetic nanocrystalline metal or alloy sheet-shaped particles with internal grain orientation and microwave absorbing material
  • Soft magnetic nanocrystalline metal or alloy sheet-shaped particles with internal grain orientation and microwave absorbing material
  • Soft magnetic nanocrystalline metal or alloy sheet-shaped particles with internal grain orientation and microwave absorbing material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] Put 10 g of commercially available carbonyl iron powder into a tube furnace, heat-treat at 275° C. for 1 h under an argon atmosphere, and obtain carbonyl iron powder with an average grain size of 50 nm. Put the heat-treated spherical carbonyl iron powder into a 2.5L stainless steel ball mill jar, add 800g of zirconia balls with a diameter of 6mm and 100mL of absolute ethanol for ball milling, and the ball milling time is controlled at 14h. After ball milling, the resulting slurry was filtered and dried to obtain the final product. Such as figure 1 Shown is the SEM image of the flaky particles prepared in this example, and the results shown in the figure show that the product is a flaky particle with an average aspect ratio of about 84.

[0043] The obtained flake particles and paraffin were mixed evenly at a weight ratio of 3.3:1, placed in a rotatable heating plate with a uniform magnetic field at a temperature of 80°C, and the magnetic field strength was about 200Gau...

Embodiment 2

[0046] The preparation technology of flake particle is identical with embodiment 1, and the flake particle obtained is identical with embodiment 1, and its scanning electron microscope picture is as follows figure 1 As shown, the difference is that no magnetic field is applied for orientation when the flake particles are mixed with paraffin to prepare the absorbing material. The X-ray diffraction pattern of the composite wave-absorbing material gained in this comparative example is as follows figure 2 As shown, it can be seen from the figure that the absorbing material does not show grain orientation. The microwave-absorbing material of this comparative example is made into a coaxial ring with an inner diameter of 3mm and an outer diameter of 7mm for electromagnetic parameter testing. The electromagnetic parameters of the microwave-absorbing material of this embodiment are as follows: Figure 4 As shown, the results show that the absorbing material can obtain the imaginary p...

Embodiment 3

[0049] Put 10 g of commercially available carbonyl iron powder into a tube furnace, and heat-treat at 150° C. for 4 h, and at 270, 300, and 330° C. for 1 h under an argon atmosphere. Five samples of the original powder and the heat-treated spherical carbonyl iron powder were placed in a 2.5L stainless steel ball milling tank, and 800g of zirconia balls with a diameter of 6mm and 100mL of absolute ethanol were added for ball milling. The ball milling time was controlled at 18 , 16, 12, 16, 20h, the flake particles with the largest aspect ratio were obtained. After ball milling, the resulting slurry was filtered and dried to obtain the final product.

[0050] Mix the obtained five flake particles with paraffin at a weight ratio of 3.3:1, place them in a rotatable heating plate with a uniform magnetic field at a temperature of 80°C, and the magnetic field strength is about 200Gauss, stir evenly and perform rotational orientation at the same time. After mixing evenly, stop the ro...

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Abstract

The invention relates to the technical field of electromagnetic functional materials, in particular to soft magnetic nanocrystalline metal or alloy sheet-shaped particles with internal grain orientation and a microwave absorbing material. The soft magnetic nanocrystalline metal or alloy sheet-shaped particles with the internal grain orientation are obtained by taking spherical or spheroidic soft magnetic metal or alloy particles with a certain grain size as a raw material and carrying out wet ball milling or stirring milling. According to the invention, grain orientation is introduced into soft magnetic nanocrystalline metal or alloy absorbent particles, and the obtained soft magnetic sheet-shaped particles have significantly improved magnetic loss, especially at the frequency of 4 GHz orbelow, and can be used as a high-quality microwave absorbent to effectively improve the low-frequency and broadband absorption performance of the wave-absorbing material.

Description

technical field [0001] The invention relates to the technical field of electromagnetic functional materials, in particular to a soft magnetic nanocrystalline metal or alloy flake particle and a microwave absorbing material with internal crystal grain orientation. Background technique [0002] Radar absorbing materials can convert electromagnetic waves into heat energy and other forms of energy and dissipate them to absorb electromagnetic waves. "Thin, light, wide, and strong" radar absorbing materials are widely used in military and civilian fields, and their common use frequency covers 0.5-18GHz. It is more difficult to absorb low-frequency electromagnetic waves, and communication frequencies such as GPS, wireless connections, etc. They are all in the lower operating frequency below 4GHz. With the increase of communication equipment, electromagnetic interference and pollution problems have become increasingly prominent, and the demand and performance requirements for low-f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/147H01Q17/00H05K9/00
CPCH01F1/14716H01Q17/002H05K9/0083
Inventor 官建国王峰李维龙昌
Owner WUHAN UNIV OF TECH
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