High-performance soft magnetic composite material based on rapid heat treatment technology and preparation and application method thereof

Abstract

The invention discloses a high-performance soft magnetic composite material based on a rapid heat treatment technology and a preparation and application method thereof. The high-performance soft magnetic composite material is obtained by pretreating gas-atomized FeSiAl powder in hot water at 80 DEG C for 2 hours and then rapidly treating the gas-atomized FeSiAl powder in rapid heat treatment equipment at 1000 DEG C for 5 seconds, the surface of the gas-atomized FeSiAl powder is coated with an Al2O3 insulating layer with the thickness of 10-20 nm, the electrical resistivity of the insulating layer is high, and the high-performance soft magnetic composite material can be used as a high-performance soft magnetic composite material. Therefore, the saturation flux density and the cut-off frequency of the material can be remarkably improved, and the high-frequency loss is reduced. The soft magnetic composite material and silicon resin are mixed, subjected to compression molding and annealed for 1-2 hours at the temperature of 600-750 DEG C in a protective atmosphere, and the soft magnetic composite material can be applied to MHz-band efficient power supply systems, such as Buck, Boost and LLC resonant converters, isolated DC-DC converters or PFC circuits, and has important industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, and relates to soft magnetic composite materials, particularly to high-performance soft magnetic composite materials based on rapid thermal processing (RTP) technology and their preparation and application methods. Background Technology

[0002] Soft magnetic composite materials (magnetic powder cores) are soft magnetic materials with high saturation magnetic flux and high resistivity, formed by insulating the soft magnetic alloy. They are widely used in inductors, reactors, and transformers. With the development of artificial intelligence technology, higher demands are placed on the efficiency and size of high-performance AI chips and server power supplies. Soft magnetic devices, as the core of energy conversion, face increasingly higher demands on the high-frequency performance of soft magnetic composite materials due to the application of wide-bandgap semiconductors. Traditional soft magnetic composite materials suffer from high hysteresis loss, large eddy current loss, and low cutoff frequency in the MHz band. Existing insulating layer preparation methods such as resin coating and phosphate passivation exhibit significant magnetic dilution effects, affecting saturation magnetic flux density and permeability.

[0003] In-situ oxidation technology can achieve insulation without introducing non-magnetic materials, and is expected to alleviate the structural contradiction between hysteresis loss and eddy current loss, obtaining soft magnetic composite materials with high saturation magnetic induction, high permeability and low loss at high frequencies. However, due to the component segregation phenomenon caused by high-temperature atomic diffusion, current in-situ oxidation technologies often adopt low-temperature oxidation processes, which have problems such as long reaction cycles, low resistivity and large thickness of the insulating layer, and decreased magnetic properties. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a high-performance soft magnetic composite material based on rapid thermal processing (RTP) technology, along with its preparation and application methods. By performing high-temperature, short-time processing, an ultra-thin, high-resistivity oxide composite insulating layer is formed in situ on the powder surface, achieving a soft magnetic composite material with high saturation magnetic induction, low loss, and high cutoff frequency. This material is particularly suitable for high-efficiency power conversion devices in the MHz frequency band.

[0005] The high-performance soft magnetic composite material based on rapid thermal processing technology includes gas-atomized FeSiAl powder and an Al2O3 insulating layer coated on the surface. The thickness of the insulating layer is 10~20 nm.

[0006] Preferably, the high-performance soft magnetic composite material is obtained by pretreating gas-atomized FeSiAl powder in hot water at 80~90℃ for 1~3 hours, and then heat-treating it at 900~1100℃ for 1~30 seconds in a rapid heat treatment device.

[0007] The preparation method of high-performance soft magnetic composite materials based on rapid heat treatment technology includes the following steps:

[0008] Step 1, Raw material preparation: Select gas-atomized FeSiAl powder.

[0009] Step 2, Hot water pretreatment: Treat the FeSiAl powder in hot water at 80~90℃ for 1~3 hours to form a uniform initial oxide layer.

[0010] Step 3, rapid heat treatment: The pretreated powder is treated in a rapid heat treatment device at 900~1100℃ for 1~30 seconds. At high temperature, Al atoms in the FeSiAl matrix diffuse to the surface and react with surface oxides to form a high resistivity Al2O3 insulating layer.

[0011] Preferably, the particle size D50 of the gas-atomized FeSiAl powder is 15~30μm.

[0012] Preferably, the rapid heat treatment is performed at a temperature of 1000°C for a time of 5 seconds.

[0013] The application method of high-performance soft magnetic composite materials based on rapid heat treatment involves mixing the soft magnetic composite material prepared by the above method with silicone resin, pressing it into shape, and annealing it at 600~750℃ for 1~2 hours in a protective atmosphere. It is then applied to the core of inductors or other electronic components in Buck, Boost, LLC resonant converters, isolated DC-DC converters, or PFCs in the MHz band.

[0014] The invention has the following beneficial effects:

[0015] 1. Based on the traditional process of in-situ oxidation technology, this invention introduces a hot water pretreatment process, which forms a uniform initial oxide layer on the surface of the metal powder, greatly shortening the time of subsequent high-temperature treatment. Therefore, the insulating layer covering the surface of the metal powder is ultra-thin, only about 15 nm, which effectively reduces the magnetic dilution effect and hysteresis loss, while increasing the saturation magnetic induction intensity by 3%~5%.

[0016] 2. During the rapid processing, a high-resistivity Al2O3 insulating layer is generated in situ, which increases the cutoff frequency of the soft magnetic composite material to over 200 MHz while reducing eddy current losses; under conditions of 3 MHz and 15 mT, the loss is less than 950 mW / cm. 3 It is suitable for high-efficiency power conversion devices in the MHz band.

[0017] 3. The insulation process does not involve any acids, alkalis or other chemicals, making it a green and environmentally friendly technology. Attached Figure Description

[0018] Figure 1 A schematic diagram and heating / cooling curves of a rapid heat treatment device;

[0019] Figure 2 These are the performance test results of samples obtained by different treatment methods in Example 1;

[0020] Figure 3 This is a TEM image of FeSiAl powder after rapid heat treatment for 10 seconds in Example 2;

[0021] Figure 4 The image shows the XRD patterns of FeSiAl powder after rapid heat treatment at different temperatures for 10 seconds in Example 3. Detailed Implementation

[0022] The present invention will be further explained below with reference to the accompanying drawings;

[0023] Example 1

[0024] Take atomized FeSiAl powder with a particle size D50 of 21 μm, treat it in hot water at 80℃ for 2 hours, and then treat it at 1000℃ for 5 seconds in a rapid heat treatment device. Figure 1 As shown, (a) is a schematic diagram of the rapid heat treatment equipment, and (b) is the temperature curve of the rapid heat treatment. It can be seen that the high-temperature treatment time is very short in the entire rapid heat treatment process.

[0025] The powder after rapid heat treatment was mixed with 1 wt% silicone resin, pressed into ring-shaped samples, and annealed at 700°C for 1 hour.

[0026] Simultaneously, FeSiAl powder fumed by gas atomization and FeSiAl powder fumed only by hot water treatment were pressed and annealed into ring-shaped samples, and their permeability, power loss, and cutoff frequency changes were measured. Figure 2 As shown. Tests show that the ring-shaped sample after rapid heat treatment using this method has an insulating layer thickness of approximately 15 nm, a saturation magnetic induction of 125.0 emu / g, a cutoff frequency of 270 MHz, and a loss of 946.4 mW / cm² at 3 MHz and 15 mT. 3 Compared to the original powder and the powder treated with hot water, the material treated by this method shows a significant increase in cutoff frequency and a significant reduction in high-frequency loss.

[0027] Example 2

[0028] Based on Example 1, the rapid heat treatment time was adjusted to 10 seconds, and the TEM image of FeSiAl powder is shown below. Figure 3 As shown, the insulating coating layer is very uniform and dense, with a thickness of approximately 20 nm. The coating layer is mainly composed of Al₂O₃, with a small amount of SiO₂, resulting in a very high resistivity.

[0029] The annealed toroidal sample was measured to have a saturation magnetic induction of 123.5 emu / g, a cutoff frequency of 290 MHz, and a loss of 1082.4 mW / cm³ at 3 MHz and 15 mT.

[0030] Example 3

[0031] Based on Example 2, rapid heat treatment was performed at 700~1100 degrees Celsius for 10 seconds at 100°C intervals. The XRD patterns of the FeSiAl powder are shown below. Figure 4 As shown in (a), (b) is a magnified view of (a) near the XRD peak. From Figure 4 As can be seen, when the rapid heat treatment temperature reaches 900℃, obvious peak separation appears in the XRD peaks, indicating that atomic diffusion and component segregation occur in the FeSiAl matrix. The segregated Al atoms further react with the coating layer produced by the pretreatment to form a high resistivity Al2O3 insulating layer.

Claims

1. A high-performance soft magnetic composite material based on rapid heat treatment, characterized in that: The high-performance soft magnetic composite material includes atomized FeSiAl powder and an Al2O3 insulating layer coated on the surface; the thickness of the insulating layer is 10~20nm.

2. The high-performance soft magnetic composite material based on rapid heat treatment as described in claim 1, characterized in that: The high-performance soft magnetic composite material is obtained by pretreating gas-atomized FeSiAl powder in hot water at 80~90℃ for 1~3 hours, and then heat-treating it at 900~1100℃ for 1~30 seconds in a rapid heat treatment device.

3. A method for preparing high-performance soft magnetic composite materials based on rapid heat treatment technology, characterized in that: The atomized FeSiAl powder was pretreated in hot water at 80-90℃ for 1-3 hours, and then heat-treated at 900-1100℃ for 1-30 seconds in a rapid heat treatment device.

4. The method for preparing a high-performance soft magnetic composite material based on rapid heat treatment technology as described in claim 3, characterized in that: The atomized FeSiAl powder was pretreated in hot water at 80°C for 2 hours, and then treated at 1000°C for 5 seconds in a rapid heat treatment device.

5. The method for preparing a high-performance soft magnetic composite material based on rapid heat treatment technology as described in claim 3, characterized in that: The D50 of the atomized FeSiAl powder is 21 μm.

6. An application of a high-performance soft magnetic composite material based on rapid heat treatment technology, characterized in that: The high-performance soft magnetic composite material as described in claim 1 or 2, or the high-performance soft magnetic composite material prepared by any of the methods described in claims 3 to 5, is applied to a power supply system in the MHz band.

7. The application of the high-performance soft magnetic composite material based on rapid heat treatment technology as described in claim 6, characterized in that: The high-performance soft magnetic composite material is mixed with silicone resin, pressed into shape, and annealed at 600~750℃ for 1~2 hours in a protective atmosphere to prepare electronic components required for a MHz band power supply system.

8. The application of the high-performance soft magnetic composite material based on rapid heat treatment technology as described in claim 6, characterized in that: The power supply system is a Buck, Boost, LLC resonant converter, isolated DC-DC converter, or PFC.

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