Soft magnetic composite material with low loss and high direct current bias and preparation method and application thereof

Abstract

The invention relates to the technical field of magnetic materials, in particular to a low-loss high-direct-current-bias soft magnetic composite material and a preparation method and application thereof.The low-loss high-direct-current-bias soft magnetic composite material is composed of nanometer titanium dioxide and iron-silicon-aluminum alloy powder; the nano titanium dioxide and the iron-silicon-aluminum alloy powder are combined in a core-shell structure form, the iron-silicon-aluminum alloy powder is used as a core, and the outer side of the iron-silicon-aluminum alloy powder is coated with a nano titanium dioxide shell. The soft magnetic composite material with low loss and high direct current bias has high direct current bias performance, relatively high magnetic conductivity and relatively low high-frequency loss, meanwhile, the preparation process of the soft magnetic composite material is simple, the prepared material has stable performance and very high direct current bias performance, and the soft magnetic composite material can be used for industrial batch production and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic materials, and in particular to a low-loss and high-DC bias soft magnetic composite material, a preparation method thereof, and applications thereof. Background Art

[0002] DC bias performance is a key concept in electronic circuits. It primarily involves setting the appropriate quiescent operating point (Q-point) for active devices (such as transistors and operational amplifiers) to ensure proper circuit operation when amplifying or processing signals. Its performance directly impacts key circuit specifications such as linearity, gain, distortion, and stability. In recent years, with the rapid development of new energy sources, SMCs have faced increasing demands for high-frequency operation, low loss, and high DC bias. Most raw FeSiAl powders exhibit high losses and poor DC bias performance in heavily loaded circuits. Summary of the Invention

[0003] In response to the above problems, the purpose of the present invention is to provide a low-loss, high DC bias soft magnetic composite material, and its preparation method and application. The low-loss, high DC bias soft magnetic composite material has high DC bias performance, high magnetic permeability and low high-frequency loss. At the same time, the preparation process of the soft magnetic composite material is simple, the prepared material has stable performance, has high DC bias performance, can be used for industrial mass production, and has broad application prospects.

[0004] In order to achieve the above object, in a first aspect, a low-loss and high DC bias soft magnetic composite material is provided, wherein the low-loss and high DC bias soft magnetic composite material is composed of nano-titanium dioxide and sendust alloy powder; The nano-titanium dioxide and the sendust alloy powder are combined in the form of a core-shell structure, wherein the sendust alloy powder is used as the core and the outer side is covered with the nano-titanium dioxide shell.

[0005] Preferably, the content of nano-titanium dioxide in the low-loss and high DC bias soft magnetic composite material is 1-4 wt %.

[0006] In a second aspect, the present invention provides a method for preparing a low-loss and high DC bias soft magnetic composite material, the preparation method comprising: liquid grinding, ring pressing, and annealing Sendust aluminum alloy powder and nano-silicon dioxide.

[0007] Preferably, the mass ratio of the Sendust alloy powder to nano-silicon dioxide is 100:8 to 100:4.

[0008] Preferably, the conditions for the liquid-addition grinding include: the liquid medium is alcohol, and the grinding time is 20 to 40 minutes.

[0009] Preferably, the conditions of the pressing ring include: a pressure of 1200-1800 MPa and a pressure holding time of 1-5 min.

[0010] Preferably, the annealing conditions include: being carried out in a vacuum or nitrogen environment, at a temperature of 600-700° C., a holding time of 1-2 h, and a heating rate of 2-8° C. / min.

[0011] Preferably, the vacuum degree is ≤10 -2 Pa.

[0012] In a third aspect, the present invention provides a low-loss and high DC bias soft magnetic composite material prepared by the preparation method described in the second aspect.

[0013] In a fourth aspect, the present invention provides a use of the low-loss and high DC bias soft magnetic composite material as described in the first aspect or the third aspect in the manufacture of power electronic equipment.

[0014] In the above technical solution, the low-loss, high DC bias soft magnetic composite material of the present invention is prepared by grinding, ring pressing, and annealing iron silicon aluminum alloy (FeSiAl) and nano titanium dioxide (TiO2), and FeSiAl is coated with nano TiO2 by a physical method. After grinding, the nano TiO2 can be well coated on the surface of the FeSiAl particles to form a uniform coating layer, thereby improving the comprehensive magnetic properties of the composite powder core, so that the soft magnetic composite material of the present invention has high DC bias performance while also having high magnetic permeability and low high-frequency loss (20mT, 1000kHz).

[0015] The low-loss, high DC bias soft magnetic composite material of the present invention can have a percentage magnetic permeability of 86.92% under an external field of 100oe. This property is crucial for power electronic equipment (such as inductors, transformers, and magnetic amplifiers) operating under high frequency, high power, or DC superimposed AC conditions, and is conducive to the use of the soft magnetic composite material in high-load scenarios.

[0016] At the same time, the preparation process of the soft magnetic composite material of the present invention is simple, the prepared soft magnetic composite material has stable performance, high DC bias performance, high magnetic permeability and low high-frequency loss, and can be used for industrial mass production.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 XRD patterns of the soft magnetic composite materials of Examples 1-4 and Comparative Example 1 of the present invention; Figure 2 The SEM images of the soft magnetic composite materials of Example 1, Examples 3-4 and Comparative Example 1 of the present invention are shown; Figure 3 EDS elemental maps of Si and Ti distribution on the soft magnetic composite materials of Examples 1-4 of the present invention; Figure 4 (a) is the real magnetic permeability (μ') of the soft magnetic composite materials of Examples 1-4 of the present invention and Comparative Example 1 as a function of frequency (magnetic flux density: 20 mT); (b) is the imaginary magnetic permeability (μ'') of the soft magnetic composite materials of Examples 1-4 of the present invention and Comparative Example 1 (magnetic flux density: 20 mT) as a function of frequency; Figure 5 (a) is the loss curve of the soft magnetic composite core of Examples 1-4 of the present invention and Comparative Example 1 as a function of frequency; (b) is the magnetic ring loss of the soft magnetic composite period of Examples 1-4 of the present invention and Comparative Example 1; Figure 6 The functional relationship between the magnetic permeability percentage of the soft magnetic composite materials of Examples 1-4 of the present invention and Comparative Example 1 and the applied DC magnetic field. DETAILED DESCRIPTION

[0019] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0020] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0021] In a first aspect, a low-loss, high-DC bias soft magnetic composite material is provided, wherein the low-loss, high-DC bias soft magnetic composite material is composed of nano-titanium dioxide and sendust alloy powder; The nano-titanium dioxide and the sendust alloy powder are combined in the form of a core-shell structure, wherein the sendust alloy powder is used as the core and the outer side is covered with the nano-titanium dioxide shell.

[0022] The low-loss, high-DC bias soft magnetic composite material of the present invention is prepared by grinding, ring-pressing, and annealing iron silicon aluminum alloy (FeSiAl) and nano-titanium dioxide (TiO2), and then coating the FeSiAl with nano-TiO2 using a physical method. After grinding, the nano-TiO2 can be well coated on the surface of the FeSiAl particles to form a uniform coating layer, thereby improving the comprehensive magnetic properties of the composite powder core. The soft magnetic composite material of the present invention has high DC bias performance while also having high magnetic permeability and low high-frequency loss (20mT, 1000kHz).

[0023] In a preferred embodiment of the present invention, the content of nano-titanium dioxide in the low-loss and high DC bias soft magnetic composite material is 1-4 wt %.

[0024] In a second aspect, the present invention provides a method for preparing a low-loss and high DC bias soft magnetic composite material, the preparation method comprising: liquid grinding, ring pressing, and annealing Sendust aluminum alloy powder and nano-silicon dioxide.

[0025] The soft magnetic composite material of the present invention has a simple preparation process, and the prepared soft magnetic composite material has stable performance, high DC bias performance, high magnetic permeability and low high-frequency loss, and can be used for industrial batch production.

[0026] In a preferred embodiment of the present invention, the mass ratio of the Sendust alloy powder to nano-silicon dioxide is 100:8 to 100:4.

[0027] In a preferred embodiment of the present invention, the conditions for liquid grinding include: the liquid medium is alcohol, the grinding time is 20 to 40 minutes, and the ground sample nano-TiO2 is well coated on the FeSiAl surface, so that the inter-particle eddy current loss between particles is greatly reduced, and the DC bias performance of the mixed powder core is also greatly improved.

[0028] In a preferred embodiment of the present invention, the conditions of the pressing ring include: a pressure of 1200-1800 MPa and a holding time of 1-5 minutes.

[0029] In a preferred embodiment of the present invention, the annealing conditions include: being carried out in a vacuum or nitrogen environment, at a temperature of 600-700° C., a holding time of 1-2 h, and a heating rate of 2-8° C. / min.

[0030] In a preferred embodiment of the present invention, the vacuum degree is ≤10 -2 Pa.

[0031] In a third aspect, the present invention provides a low-loss and high DC bias soft magnetic composite material prepared by the preparation method described in the second aspect.

[0032] In a fourth aspect, the present invention provides a use of the low-loss and high DC bias soft magnetic composite material as described in the first aspect or the third aspect in the manufacture of power electronic equipment.

[0033] The low-loss, high-DC bias soft magnetic composite material of the present invention can have a percentage magnetic permeability of 86.92% under an external field of 100Oe. This property is crucial for power electronic equipment (such as inductors, transformers, and magnetic amplifiers) operating under high frequency, high power, or DC superimposed AC conditions, and is conducive to the use of the soft magnetic composite material in high-load scenarios.

[0034] The present invention will be described in detail below by way of examples. In the following examples, the drugs and pharmaceuticals are all conventional commercial products.

[0035] Example 1 (1) Ingredients: FeSiAl and nano-TiO2 are used as raw materials, and the raw materials are weighed according to the sample mass ratio of 96:4; (2) Grinding: Place the raw materials weighed in step (1) into a mortar, add an appropriate amount of alcohol, and grind for 0.5 h to obtain sample powder; (3) Tablet pressing: Pour the sample powder into the pressing ring mold, apply a pressure of 1500 MPa, and maintain the pressure for 1 min to form a sample ring; (4) Annealing: The pressed sample ring is placed in a vacuum furnace for vacuum annealing at a heating rate of 5 °C / min, an annealing temperature of 650 °C, and an annealing time of 1.5 hours. After annealing, it is naturally cooled to room temperature to obtain a low-loss and high DC bias soft magnetic composite material.

[0036] Example 2 The method described in Example 1 was followed, except that the "mass ratio of 96:4" in step (1) was replaced by "mass ratio of 99:1" to obtain a soft magnetic composite material.

[0037] Example 3 The method described in Example 1 was followed, except that the "mass ratio of 96:4" in step (1) was replaced by "mass ratio of 98:2" to obtain a soft magnetic composite material.

[0038] Example 4 The method described in Example 1 was followed, except that the "mass ratio of 96:4" in step (1) was replaced by "mass ratio of 97:3" to obtain a soft magnetic composite material.

[0039] Comparative Example 1 The method described in Example 1 was followed, except that the "mass ratio of 96:4" in step (1) was replaced by "mass ratio of 100:0" to obtain a soft magnetic composite material.

[0040] Test Example 1 The soft magnetic composite materials obtained in Examples 1-4 and Comparative Example 1 were analyzed by X-ray diffractometer (XRD). Figure 1 .

[0041] Depend on Figure 1 It can be seen from the content that all samples have no miscellaneous items, but in the soft magnetic composite materials prepared in Comparative Example 1 and Example 2-Example 4, when the addition amount of TiO2 is 0wt%-3wt%, the XRD cannot detect the peak of TiO2 due to the small content of TiO2; in the soft magnetic composite material prepared in Example 1, when the addition amount of TiO2 is 4wt%, a main peak of TiO2 can be seen.

[0042] Test Example 2 The surface morphology of the soft magnetic composite materials obtained in Example 1, Examples 3-4 and Comparative Example 1 was observed using a scanning electron microscope (SEM). Figure 2 ; EDS elemental maps of Si and Ti distribution on the soft magnetic composite materials of Examples 1-4 are shown in Figure 3 .

[0043] Depend on Figure 2-Figure 3 From the content, we can see that after grinding, nano-TiO2 is well coated on the surface of FeSiAl.

[0044] Test Example 3 The magnetic loss and magnetic permeability of the soft magnetic composite materials prepared in Examples 1-4 and Comparative Example 1 were tested under different magnetic fields and frequencies using a BH analyzer (SY-8218). Figure 4-Figure 5 .

[0045] like Figure 4 is the real part of the magnetic permeability of samples with different TiO2 contents μ' and the imaginary part μ" The curve changes with frequency, and the tested magnetic flux density is equal to 20mT. Figure 4 (a) It can be seen that the true magnetic permeability of the soft magnetic composite materials prepared in Examples 1-4 and Comparative Example 1 is μ There is no obvious change with the increase of frequency, which shows that TiO2 coating does not affect the frequency stability of the soft magnetic composite material. At the same time, it can be seen that the real part of the magnetic permeability of the soft magnetic composite material increases with the increase of TiO2 addition. μ' gradually decreases, which can be explained by the fact that as the coating agent content increases, the non-magnetic TiO2 coating on the FeSiAl surface becomes more, and the distributed air gap in the composite material becomes larger, which makes the real part of the magnetic permeability μ 'decline.

[0046] Depend on Figure 4 (b) It can be seen that the change in the imaginary part of the magnetic permeability is related to the real part of the magnetic permeability μ' On the contrary, the imaginary part of the permeability μ" As the frequency increases, the imaginary part of the magnetic permeability of the soft magnetic composite material treated with TiO2 coating in Example 1-4 increases. μ" The increase in the imaginary part of the magnetic permeability is much smaller than that of the soft magnetic composite material without TiO2 coating in Comparative Example 1, and the imaginary part of the magnetic permeability increases with the increase in the amount of TiO2 added. μ" The increase in the magnitude of the magnetic permeability decreases with increasing frequency. μ" It is positively correlated with the loss. The eddy current loss of the soft magnetic composite materials coated with TiO2 in Examples 1-4 is greatly reduced, resulting in a reduction in the total loss and the above-mentioned law.

[0047] like Figure 5 (a) is the curve of total loss of soft magnetic composite materials with different TiO2 contents varying with frequency, and the magnetic flux density tested is equal to 20mT. Figure 5 (a) It can be seen that the total loss of the soft magnetic composite material increases with the increase of frequency, but the total loss of the soft magnetic composite material coated with TiO2 first decreases and then increases with the increase of coating amount, but is still greater than that of the uncoated soft magnetic composite material. Among them, when the addition amount is 3wt%, the total loss reaches a minimum of 557mW / cm at a frequency field of 1000kHz. 3 , which is 32.6% lower than the total loss of the soft magnetic composite material of Comparative Example 1 without adding TiO2 coating.

[0048] like Figure 5 (b) is a graph that separates the losses of all soft magnetic composite materials. In the graph, it can be seen that the eddy current loss shows a trend of first decreasing and then increasing as the coating amount increases. However, by comparing the soft magnetic composite material without TiO2 coating in Comparative Example 1 and the soft magnetic composite material coated with TiO2 in Examples 1-4, it can be seen that the eddy current loss of the soft magnetic composite material of Examples 1-4 is greatly reduced, and when the addition amount of TiO2 is 4wt%, the eddy current loss increases slightly, which just verifies the previous SEM results. At this time, excessive TiO2 makes the coating layer on the surface of the magnetic powder thicker, and the agglomerated and agglomerated TiO2 may also cause the coating layer to crack and fall off during the pressing process, resulting in more air gaps that are detrimental to the insulation coating effect.

[0049] Test Example 4 The DC bias performance of the soft magnetic composite materials prepared in Examples 1-4 and Comparative Example 1 was tested using a comprehensive reactance tester (DPG10-1500A). The results are shown in Table 1. Figure 6 .

[0050] like Figure 6 Shown is the percentage magnetic permeability of each soft magnetic composite material in a DC bias magnetic field. As can be seen from the figure, under the same DC bias field of 100Oe, the percentage magnetic permeability of the soft magnetic composite materials coated with TiO2 in Examples 1-4 is greater than that of the uncoated soft magnetic composite material in Comparative Example 1, and as the amount of TiO2 added increases, the percentage magnetic permeability of the soft magnetic composite material also increases. When the addition amount is 4wt%, the percentage magnetic permeability increases from 66.57% to 86.92%. The TiO2 coating greatly improves the DC bias performance of the soft magnetic composite material.

[0051] In summary, the low-loss, high DC bias soft magnetic composite material of the present invention has a lower magnetic permeability than the pure FeSiAl powder core, but the total loss is greatly reduced. The magnetic powder coated with 3wt% TiO2 has the best comprehensive soft magnetic properties. The real part of the magnetic permeability at 1000KHz is μ' is 37.51, and the losses at 20mT are 557kW / m 3 At the same time, the DC bias performance is excellent, with a percentage permeability of 86.92% at an external magnetic field of 100 Oe. The present invention provides a method for preparing high-frequency and low-loss FeSiAl.

[0052] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0053] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0054] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A low-loss, high-DC bias soft magnetic composite material, characterized in that: The low-loss, high-DC bias soft magnetic composite material is composed of nano-titanium dioxide and sendust alloy powder; The nano-titanium dioxide and the sendust alloy powder are combined in the form of a core-shell structure, wherein the sendust alloy powder is used as the core and the outer side is covered with the nano-titanium dioxide shell.

2. The soft magnetic composite material according to claim 1, characterized in that The content of nano-titanium dioxide in the low-loss and high DC bias soft magnetic composite material is 1-4 wt %.

3. A method for preparing a low-loss and high DC bias soft magnetic composite material, characterized in that: The preparation method comprises the following steps: grinding the iron-silicon-aluminum alloy powder and nano-silicon dioxide with liquid, ring pressing, and annealing.

4. The preparation method according to claim 3, characterized in that The mass ratio of the Sendust alloy powder to nano-silicon dioxide is 100:8 to 100:

4.

5. The preparation method according to claim 3 or 4, characterized in that The conditions for the liquid-addition grinding include: the liquid medium is alcohol, and the grinding time is 20 to 40 minutes.

6. The preparation method according to claim 3, characterized in that The conditions of the pressing ring include: a pressure of 1200~1800Mpa and a pressure holding time of 1~5min.

7. The preparation method according to claim 3, characterized in that The annealing conditions include: being carried out in a vacuum or nitrogen environment, a temperature of 600-700° C., a holding time of 1-2 hours, and a heating rate of 2-8° C. / min.

8. The preparation method according to claim 7, characterized in that The vacuum degree is ≤10 -2 Pa.

9. A soft magnetic composite material with low loss and high DC bias obtained by the preparation method according to any one of claims 3 to 8.

10. Use of the low-loss and high DC bias soft magnetic composite material according to claim 1 or 2 or the low-loss and high DC bias soft magnetic composite material according to claim 9 in manufacturing power electronic equipment.

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