阅读说明：本技术 一种铁基非晶复合磁粉芯及其制备方法和应用 (Iron-based amorphous composite magnetic powder core and preparation method and application thereof ) 是由 斯佳佳 任潞 高炜 于 2021-07-09 设计创作，主要内容包括：本发明属磁性材料技术领域,公开了一种铁基非晶复合磁粉芯及其制备方法和应用,其中,铁基非晶复合磁粉芯采用PTFE粉末对铁基非晶合金粉末进行包覆,PTFE的加入能够减轻磁粉颗粒间的滑动阻力,降低粉芯成型时的压力,提高磁粉芯的致密度,从而进一步提高磁粉芯的饱和磁感应强度；同时,由于PTFE的烧结固化温度与铁基非晶合金的退火温度接近,因此只需进行一次热处理即可同时实现磁粉芯的烧结和去应力退火；且经热处理后的PTFE颗粒实现了连接固化,大幅提升磁性的力学性能,并安全消除压制过程带来的内应力和材料本身的残余应力,从而进一步显著改善磁粉芯的磁学性能。本发明的铁基非晶复合磁粉芯具有高饱和磁感应强度和低损耗特性,可应用在电子器件中。(The invention belongs to the technical field of magnetic materials, and discloses an iron-based amorphous composite magnetic powder core and a preparation method and application thereof, wherein the iron-based amorphous composite magnetic powder core is prepared by coating iron-based amorphous alloy powder with PTFE powder, and the addition of PTFE can reduce the sliding resistance among magnetic powder particles, reduce the pressure during powder core molding, and improve the density of the magnetic powder core, thereby further improving the saturation magnetic induction intensity of the magnetic powder core; meanwhile, the sintering and curing temperature of PTFE is close to the annealing temperature of the iron-based amorphous alloy, so that the sintering and stress relief annealing of the magnetic powder core can be realized simultaneously only by carrying out heat treatment once; and the PTFE particles after heat treatment realize connection and solidification, greatly improve the mechanical property of magnetism, and safely eliminate the internal stress caused by the pressing process and the residual stress of the material, thereby further obviously improving the magnetic property of the magnetic powder core. The iron-based amorphous composite magnetic powder core has the characteristics of high saturation magnetic induction intensity and low loss, and can be applied to electronic devices.)

1. An iron-based amorphous composite magnetic powder core is characterized by comprising iron-based amorphous alloy powder and PTFE powder.

2. The iron-based amorphous composite magnetic powder core according to claim 1, comprising 90-98.5 parts by weight of iron-based amorphous alloy powder and 1.5-10 parts by weight of PTFE powder.

3. The iron-based amorphous composite magnetic powder core according to claim 1 or 2, wherein the particle size of the iron-based amorphous alloy powder is 5-30 μm.

4. The iron-based amorphous composite magnetic powder core according to claim 1 or 2, wherein the particle size of the PTFE powder is 0.5-5 μm.

5. The Fe-based amorphous composite magnetic powder core as claimed in claim 1, wherein the Fe-based amorphous alloy powder component is Fe₇₃Si₁₁B₁₁C₃Cr₂Or Fe₇₈Si₉B₁₃。

6. The method for preparing the iron-based amorphous composite magnetic powder core according to any one of claims 1 to 5, comprising the steps of: mixing iron-based amorphous alloy powder and PTFE powder, performing compression molding, and performing heat treatment under the condition of inert gas to obtain the iron-based amorphous composite magnetic powder core.

7. The method as claimed in claim 6, wherein the pressure for the press molding is 600-1800 MPa.

8. The method according to claim 6, wherein the heat treatment comprises: heating to the temperature of 360-390 ℃ in a heat treatment furnace, and preserving the heat for 0.5-1.5 h.

9. The method according to claim 6, wherein the iron-based amorphous composite magnetic powder core is annular in shape.

10. Use of the iron-based amorphous composite magnetic powder core according to any one of claims 1 to 5 in an electronic device.

Technical Field

The invention belongs to the technical field of magnetic materials, and particularly relates to an iron-based amorphous composite magnetic powder core and a preparation method and application thereof.

Background

The iron-based amorphous soft magnetic alloy has the advantages of high saturation magnetic induction intensity, low coercive force and low loss, and has important application in the field of soft magnetic materials. The application of the iron-based amorphous alloy strip in the aspects of transformers, transformers and the like tends to be mature, and researchers have been making efforts to develop a high-performance iron-based amorphous composite magnetic powder core material in order to better meet the strong demand of electronic equipment on high-performance inductor components.

Different from the traditional soft magnetic alloy, the iron-based amorphous alloy is in a metastable state, and is crystallized when the temperature exceeds the crystallization temperature (about 550 ℃), so that the mechanical and magnetic properties of the iron-based amorphous alloy are changed rapidly. Therefore, the iron-based amorphous alloy magnetic powder core is difficult to prepare by adopting the traditional high-temperature sintering method. At present, the preparation process of the iron-based amorphous alloy magnetic powder core generally comprises the following steps: powder mixing, passivation treatment, coating treatment, press forming and annealing heat treatment; or adopting powder preparation, powder mixing, passivation, coupling, insulation coating, lubrication treatment, compression molding, annealing heat treatment and spraying insulation treatment; or adopting powder mixing, passivation treatment, bonding, coating granulation treatment, compression molding treatment and annealing heat treatment. The powder mixing, passivating and coating treatment is to realize good insulation among magnetic particles and better press forming; the formed powder has large internal stress, and the stress is eliminated by heat treatment to improve the magnetism. Therefore, the existing preparation process flow of the iron-based amorphous magnetic powder core is complicated, and the preparation process of the magnetic powder core can be optimized and the process flow can be reasonably reduced as far as possible on the premise of ensuring the relevant performance of the magnetic powder core, so that the preparation efficiency of the magnetic powder core is improved and the cost is reduced.

However, the insulating agents in the iron-based amorphous composite magnetic powder core are mainly epoxy resin, silicon resin, polyamide resin and the like at present, and although the organic resins have good insulating performance, the following problems generally exist: 1) the material is not high in temperature resistance, so that the heat treatment temperature is limited, the magnetism is not favorably improved, the use temperature is limited, and the application scene is limited; 2) the lubricating property is poor, and a lubricating agent (such as mica powder and the like) needs to be additionally added to improve the density of the magnetic powder core; 3) the structural strength is ensured by means of molding pressure, and the resin mainly plays a role in insulating coating, so that the magnetic powder core prepared is insufficient in magnetic performance and mechanical performance, weak in overall strength and incapable of meeting the requirements.

Disclosure of Invention

The invention provides an iron-based amorphous composite magnetic powder core and a preparation method and application thereof, which are used for solving one or more technical problems in the prior art and at least providing a beneficial choice or creation condition.

In order to overcome the technical problems, the technical scheme adopted by the invention is as follows:

an iron-based amorphous composite magnetic powder core comprises iron-based amorphous alloy powder and PTFE powder.

Specifically, PTFE, commonly known as "plastic king", is a high molecular compound formed by polymerizing tetrafluoroethylene, and has good lubricating properties, so that on one hand, the wear effect of metal magnetic particles on a die in a cold pressing process can be effectively relieved; on the other hand, the addition of PTFE can reduce the sliding resistance among the magnetic powder particles, reduce the pressure during the powder core forming, and improve the density of the magnetic powder core, thereby improving the saturation magnetic induction intensity of the magnetic powder core.

As a further improvement of the scheme, the iron-based amorphous composite magnetic powder core comprises 90-98.5 parts by weight of iron-based amorphous alloy powder and 1.5-10 parts by weight of PTFE powder.

Specifically, the addition amount of the PTFE powder is too small to ensure good insulation of the magnetic powder core; too much addition leads to deterioration of the magnetic properties of the material, including reduction of saturation induction and increase of hysteresis loss.

As a further improvement of the scheme, the iron-based amorphous alloy powder is iron-based amorphous soft magnetic powder and comprises Fe₇₃Si₁₁B₁₁C₃Cr₂Or Fe₇₈Si₉B₁₃At least one of (1).

As a further improvement of the scheme, the particle size of the iron-based amorphous alloy powder is 5-30 μm.

Specifically, the problem of too fine powder is that the preparation cost of amorphous powder is too high, and the problem of too coarse powder is not favorable for improving the resistance of the composite magnetic powder core and reducing the loss of the magnetic powder core.

As a further improvement of the scheme, the particle size of the PTFE powder is 0.5-5 μm, and the smaller particle size is beneficial to the dispersion of the PTFE powder on the periphery of the iron-based amorphous alloy powder to form a tiny insulating layer.

The preparation method of the iron-based amorphous composite magnetic powder core comprises the following steps: mixing iron-based amorphous alloy powder and PTFE powder, then performing compression molding, and then performing heat treatment under the condition of inert gas to obtain the iron-based amorphous composite magnetic powder core.

Specifically, the PTFE powder is deformable, the iron-based amorphous alloy powder is not deformable, and the PTFE powder can be dispersed around the iron-based amorphous alloy powder after the PTFE powder and the iron-based amorphous alloy powder are mixed to form a coating effect.

As a further improvement of the scheme, the pressure of the compression molding is 600-1800 MPa.

As a further improvement of the above scheme, the heat treatment process comprises: heating to the temperature of 360-390 ℃ in a heat treatment furnace, and preserving the heat for 0.5-1.5 h.

Specifically, when the temperature is lower than 360 ℃, the stress relief annealing effect is weakened, and the sintering performance of PTFE is deteriorated; the temperature is higher than 390 ℃, PTFE has the risk of decomposition, so the temperature of heat preservation sintering is 360-390 ℃, which is beneficial to the connection and solidification of PTFE particles, thereby greatly improving the mechanical property of the magnetic powder core.

As a further improvement of the scheme, the shape of the iron-based amorphous composite magnetic powder core is annular.

Specifically, the sintering and curing temperature of PTFE is 360-390 ℃, which is close to the annealing temperature (360-450 ℃) of the iron-based amorphous alloy, so that the sintering and stress relief annealing of the magnetic powder core can be simultaneously realized by carrying out one-time heat treatment on the pressed magnetic powder core at the temperature of 360-390 ℃, and simultaneously, PTFE particles can be connected and cured through the heat treatment, thereby greatly improving the mechanical property of the magnetic powder core; more importantly, the internal stress caused by the pressing process and the residual stress of the material can be safely eliminated below the glass transition temperature of the iron-based amorphous alloy, so that the magnetic performance of the magnetic powder core is further obviously improved. The obtained iron-based amorphous composite magnetic powder core has the characteristics of high saturation magnetic induction intensity and low loss, and has good application prospect.

The iron-based amorphous composite magnetic powder core provided by the invention is applied to electronic devices such as inductive filters, frequency modulation chokes, inverters and other components.

The invention has the beneficial effects that:

the invention provides an iron-based amorphous composite magnetic powder core and a preparation method and application thereof, wherein PTFE powder is adopted in the iron-based amorphous composite magnetic powder core to coat the iron-based amorphous alloy powder, and the addition of PTFE can reduce the sliding resistance among magnetic powder particles, reduce the pressure during powder core forming, and improve the density of the magnetic powder core, thereby further improving the saturation magnetic induction intensity of the magnetic powder core. Meanwhile, the sintering and curing temperature of PTFE is close to the annealing temperature of the iron-based amorphous alloy, so that the sintering and stress relief annealing of the magnetic powder core can be realized simultaneously only by carrying out heat treatment once; and the PTFE particles after heat treatment realize connection and solidification, greatly improve the mechanical property of magnetism, and safely eliminate the internal stress caused by the pressing process and the residual stress of the material, thereby further obviously improving the magnetic property of the magnetic powder core. The iron-based amorphous composite magnetic powder core prepared by the invention has the characteristics of high saturation magnetic induction intensity and low loss, can be applied to electronic devices such as an inductive filter, a frequency modulation choke coil and an inverter, and has wide application prospect.

Drawings

FIG. 1 is a diagram of a finished product of an iron-based amorphous composite magnetic powder core prepared by the invention;

FIG. 2 is an XRD diffraction pattern of the iron-based amorphous composite magnetic powder core prepared in example 3 of the present invention.

Detailed Description

The present invention is specifically described below with reference to examples in order to facilitate understanding of the present invention by those skilled in the art. It should be particularly noted that the examples are given solely for the purpose of illustration and are not to be construed as limitations on the scope of the invention, as non-essential improvements and modifications to the invention may occur to those skilled in the art, which fall within the scope of the invention as defined by the appended claims. Meanwhile, the raw materials mentioned below are not specified in detail and are all commercially available products; the process steps or extraction methods not mentioned in detail are all process steps or extraction methods known to the person skilled in the art.

Example 1

An iron-based amorphous composite magnetic powder core comprises Fe₇₃Si₁₁B₁₁C₃Cr₂98.4g of powder and 1.6g of PTFE powder.

The preparation method of the iron-based amorphous composite magnetic powder core comprises the following steps:

1) taking Fe with the grain diameter of 5-30 mu m₇₃Si₁₁B₁₁C₃Cr₂98.4g of iron-based amorphous alloy and 1.6g of PTFE powder with the grain diameter of 1-5 mu m are ball-milled and mixed in a proper amount of absolute ethyl alcohol for 30min, and composite powder with the PTFE mass fraction of 1.6 percent is obtained after drying;

2) taking the composite powder, pressing the composite powder into a magnetic ring (the outer diameter of the magnetic ring is 20mm, and the inner diameter of the magnetic ring is 12mm) by using a press under 1000 MPa;

3) and in the nitrogen atmosphere, heating the pressed and formed magnetic ring in a heat treatment furnace to the temperature, and preserving the heat for 1h to obtain an iron-based amorphous composite magnetic powder core finished product, so as to realize the annealing and sintering of the magnetic ring at one time.

Example 2

An iron-based amorphous composite magnetic powder core comprises Fe₇₃Si₁₁B₁₁C₃Cr₂96.4g of powder and 3.6g of PTFE powder.

The preparation method of the iron-based amorphous composite magnetic powder core comprises the following steps:

1) taking Fe with the grain diameter of 5-30 mu m₇₃Si₁₁B₁₁C₃Cr₂96.4g of iron-based amorphous alloy and 3.6g of PTFE powder with the grain diameter of 0.5-2 mu m are subjected to ball milling and mixing in a proper amount of absolute ethyl alcohol for 30min, and composite powder with the PTFE mass fraction of 3.6% is obtained after drying;

2) taking the composite powder, pressing the composite powder into a magnetic ring (the outer diameter of the magnetic ring is 20mm, and the inner diameter of the magnetic ring is 12mm) by using a press under 1000 MPa;

3) in the nitrogen atmosphere, the temperature of the pressed and formed magnetic ring is raised to 390 ℃ in a heat treatment furnace, the heat is preserved for 1h, the finished product of the iron-based amorphous composite magnetic powder core is obtained, and the annealing and sintering of the magnetic ring are realized at one time.

Example 3

An iron-based amorphous composite magnetic powder core comprises Fe₇₃Si₁₁B₁₁C₃Cr₂91g of powder and 9g of PTFE powder.

The preparation method of the iron-based amorphous composite magnetic powder core comprises the following steps:

1) taking Fe with the grain diameter of 5-30 mu m₇₃Si₁₁B₁₁C₃Cr₂91g of iron-based amorphous alloy and 9g of PTFE powder with the particle size of 0.5-2 mu m are ball-milled and mixed in a proper amount of absolute ethyl alcohol for 30min, and composite powder with the PTFE mass fraction of 9% is obtained after drying;

2) taking the composite powder, pressing the composite powder into a magnetic ring (the outer diameter of the magnetic ring is 20mm, and the inner diameter of the magnetic ring is 12mm) by using a press under 1000 MPa;

3) and in the nitrogen atmosphere, heating the pressed and formed magnetic ring in a heat treatment furnace to 380 ℃, and preserving heat for 1h to obtain an iron-based amorphous composite magnetic powder core finished product, so as to realize annealing and sintering of the magnetic ring at one time.

Example 4

Example 4 differs from example 2 in that in example 4, the pressure in step 2) is 1500 MPa.

Example 5

Example 5 is different from example 2 in that in example 4, the component of the iron-based amorphous alloy powder in step 1) is Fe₇₈Si₉B₁₃。

Comparative example 1

Comparative example 1 is different from example 2 in that the mass fraction of PTFE powder in comparative example 1 is 1.2%, specifically, Fe₇₃Si₁₁B₁₁C₃Cr₂98.8g of powder and 1.2g of PTFE powder were prepared in the same manner as in example 2. And obtaining the finished product of the iron-based amorphous composite magnetic powder core.

Comparative example 2

Comparative example 2 differs from example 2 in that the mass fraction of PTFE powder in comparative example 2 is 12%, specifically, Fe₇₃Si₁₁B₁₁C₃Cr₂88g of PTFE powder and 12g of PTFE powder were prepared in the same manner as in example 2. And obtaining the finished product of the iron-based amorphous composite magnetic powder core.

Comparative example 3

Comparative example 3 is different from example 2 in that the composition of the magnetic powder core in comparative example 3 is pure Fe₇₃Si₁₁B₁₁C₃Cr₂Powder (no PTEF added) was prepared by the same method as in example 2.

Experiments show that when no PTFE resin is added, the magnetic powder core cannot be molded and is cracked under the action of slight external force in the demolding process. This is because the iron-based amorphous powder is a highly hard and brittle metal material and cannot be directly press-molded at low temperature.

Product performance testing

The density, saturation induction and loss at 50kHz frequency of each of the finished iron-based amorphous composite magnetic powder cores obtained in examples 1 to 4 and comparative examples 1 to 2 were measured, and the results are shown in Table 1 below. The density is measured by adopting an Archimedes drainage method, and the saturation magnetic induction intensity and the loss of the magnetic powder core are respectively measured by adopting a vibration sample magnetometer and a soft magnetic alternating current measuring instrument.

TABLE 1 Performance testing of Fe-based amorphous composite magnetic powder core finished products

As can be seen from Table 1, the density of the toroidal magnetic powder core prepared by the present invention is about 5.6 to 6.3g/cm³Close to the original density of the Fe-based amorphous alloy of 7.2g/cm³It is demonstrated that the addition of the PTFE powder having a lubricating effect contributes to the improvement of the density of the magnetic powder core.

The finished product of the iron-based amorphous composite magnetic powder core prepared by the invention is shown in figure 1, and as can be seen from figure 1, the forming effect of the sintered iron-based amorphous composite magnetic powder core finished product is good. Fig. 2 is an XRD diffraction pattern of the finished product of fe-based amorphous composite magnetic powder core of example 3, as can be seen from the characteristic diffraction peak shown in fig. 2,the prepared composite magnetic ring (iron-based amorphous composite magnetic powder core) consists of an amorphous phase and a PTFE crystalline phase. This is mainly due to the fact that the sintering temperature of the heat treatment is significantly lower than the crystallization temperature of the fe-based amorphous alloy (about 550 ℃), and the amorphous powder is able to perfectly maintain the amorphous structure after the heat treatment. Although the content of PTFE is increased, the saturation magnetic induction intensity of the finished magnetic powder core product is 0.9T and still meets the requirement; under the condition of 100mT, the loss of the alloy at the frequency of 50kHz is 592mW/cm respectively³The loss is further reduced.

Meanwhile, as can be seen from examples 2 and 4, the greater forming pressure increases the density of the finished magnetic powder core product, so that the saturation magnetic induction of the magnetic powder core is increased from 1.04T to 1.08T under 1000 MPa; under the condition of 100mT, the loss of the filter is 457mW/cm respectively at the frequency of 50kHz³Compared with the magnetic powder core prepared under 1000MPa, the magnetic powder core prepared under 1000MPa has a certain degree of loss reduction, mainly because the air gaps among the magnetic powder are further reduced, the hysteresis loss is reduced, and the magnetic powder core is a further optimized scheme.

In example 5, Fe with a higher Fe content was used₇₈Si₉B₁₃The amorphous powder shows that the magnetic powder core prepared under the same condition has smaller loss difference and obviously improved saturation magnetic induction intensity, which indicates that the comprehensive magnetic performance of the magnetic powder core can be selectively regulated and controlled by the magnetic powder material.

In comparative example 1, when the PTFE content was reduced to 1.2%, the lubricant effect was reduced, and the magnetic powder core density did not increase with the increase in metal content, indicating that there were many air gaps inside and the saturation magnetic induction did not increase significantly; and the magnetic powder core loss is greatly increased to 1276mW/cm due to the increase of defects and the reduction of insulating resin³. In addition, because the content of PTFE is too low, the prepared iron-based amorphous composite magnetic powder core can be cracked under the action of small external force, and the basic mechanical property is difficult to ensure, so that the content of PTFE is not suitable to be too low.

Comparative example 2 the saturation induction of the magnetic powder core was reduced to 0.8T due to the excessively high content of PTFE, which is mainly due to the disadvantage of controlling hysteresis loss due to the excessively high content of PTFE, 100mT barsUnder the condition, the loss of the alloy at the frequency of 50kHz is greatly increased to 1000mW/cm³Therefore, the PTFE content in the composite magnetic powder core should not be too high.

The iron-based amorphous composite magnetic powder core prepared by the invention has the characteristics of high saturation magnetic induction intensity and low loss, can be applied to electronic devices such as an inductive filter, a frequency modulation choke coil and an inverter, and has wide application prospect.

It will be obvious to those skilled in the art that many simple derivations or substitutions can be made without inventive effort without departing from the inventive concept. Therefore, simple modifications to the present invention by those skilled in the art according to the present disclosure should be within the scope of the present invention. The above embodiments are preferred embodiments of the present invention, and all similar processes and equivalent variations to those of the present invention should fall within the scope of the present invention.