Magnetic powder core material with stable magnetic permeability and low loss and preparation method thereof

[0038] Example 1

[0039] Weigh 47g of water atomized pure Fe powder with an average particle size of 75μm in a beaker, add ammonia water that can wet the iron powder, stir clockwise with a glass rod for 20 minutes, and then weigh 3g of Fe with a particle size of 20nm 3 O 4 The powder is premixed in a V-type blender. Use planetary ball mill for dry ball milling, take Fe/Fe prepared by dry ball mill 3 O 4 Core-shell structure coated powder 4g, the obtained coated powder SEM image is as follows figure 1 As shown, comparing the powder surface morphology before and after ball milling, it can be seen that the smooth water atomized pure Fe powder surface is compounded in situ under the action of ball milling to obtain soft magnetic composite powder. Use VSM equipment to test the saturation magnetic induction intensity of composite powder such as image 3 As shown, it can be known that its saturation magnetic induction intensity is 207emu/g, which is only 5.9% lower than the saturation magnetic induction intensity of the original iron powder of 220emu/g, so 6% of nano-Fe 3 O 4 Addition has little effect on the original properties of the powder. Add 1% epoxy-modified silicone resin with a mass fraction of soft magnetic powder to the powder obtained by ball milling, add 1g of amorphous iron silicon boron powder, fully mechanically stir at 80 ℃, and then put the dry powder into a ring shape The alloy steel mold is pressed at room temperature at a pressure rate of 5 MPa/s, and the pressure is maintained at 800 MPa for 3 minutes to obtain an iron/ferroferric oxide block composite material with a size of 20 mm in outer diameter, 12 mm in inner diameter, and 3 mm in height. The block is subjected to vacuum heat treatment at 450℃, 1h, and the vacuum degree is ≤10 -3 Pa. Use the B-H analyzer to carry out the magnetic performance test, the sample performance obtained is shown in Table 1 (Bmax=50mT), and the effective permeability varies with the test frequency as Figure 4 Shown. by Figure 4 It can be seen that the effective permeability of the magnetic powder core block varies little with frequency and remains basically constant. Using the MATS-2010SD soft magnetic DC test system to test the DC performance, the maximum saturation magnetic flux density Bs of the sample is 1.71T, the coercivity Hc is 6.44 Oe, and the maximum permeability is 223.

[0040] Table 1

[0041] Frequency/kHz

[0042] Example 2

[0043] Weigh 47g of water atomized pure Fe powder with an average particle size of 300μm in a beaker, add ammonia water that can wet the iron powder, stir clockwise with a glass rod for 20 minutes, and then weigh 3g of Fe with a particle size of 20nm 3 O 4 The powder is premixed in a V-type blender. Use planetary ball mill for dry ball milling, take Fe/Fe prepared by dry ball mill 3 O 4 4g core-shell structure coated powder, add epoxy modified silicone resin with a mass fraction of soft magnetic powder of 1%, fully mechanically stir at 80°C, and then put the dry powder into a ring-shaped alloy steel mold to press at room temperature , Pressing at a pressure rate of 5MPa/s, and maintaining pressure at 800Mpa for 3 minutes to obtain an iron/ferric oxide block composite material with a size of 20mm in outer diameter, 12mm in inner diameter and 3mm in height. The block is subjected to vacuum heat treatment at 450℃, 1h, and the vacuum degree is ≤10 -3 Pa. Use the B-H analyzer to carry out the magnetic performance test, and the obtained sample performance is shown in Table 2 (Bmax=50mT), and the effective permeability varies with the test frequency as Figure 4 Shown. by Figure 4 It can be seen that the effective magnetic permeability of the magnetic powder core block varies little with frequency and remains basically constant, but the magnetic permeability is slightly lower than the composite magnetic powder core made of 75 μm water atomized pure Fe powder. Using the MATS-2010SD soft magnetic DC test system to test the DC performance, the maximum saturation magnetic flux density Bs of the sample is 1.44T, the coercivity Hc is 18.1 Oe, and the maximum permeability is 203.

[0044] Table 2

[0045] Frequency/kHz

[0046] Example 3

[0047] Weigh 47g of water-atomized pure Fe powder with an average particle size of 75μm in a beaker, add ammonia water that can wet the iron powder, stir the glass rod clockwise for 20 minutes, and then weigh 3g of Mn with a particle size of 50nm 0.6 Zn 0.4 Fe 2 O 4 The powder is premixed in a V-type blender. Use planetary ball mill for dry ball milling, Figure 5 Fe/Mn obtained after high-energy ball milling 0.6 Zn 0.4 Fe 2 O 4 The scanning electron micrograph of the composite powder shows that the ball milling process has the same effect on oxides of different composition or particle size, and can obtain a soft magnetic composite powder with uniform surface oxide coating. Take Fe/Mn prepared by dry ball milling 0.6 Zn 0.4 Fe 2 O 4 4g core-shell structure coating powder, add 1% soft magnetic powder mass fraction of epoxy modified silicone resin, add 0.5g amorphous iron silicon boron powder, fully mechanically stir at 80 ℃, and then put the dry powder into Pressing at room temperature in a ring-shaped alloy steel mold, pressing at a pressure rate of 5MPa/s, and holding pressure at 800Mpa for 3 minutes, to obtain an iron/manganese-zinc ferrite block composite with a size of 20mm in outer diameter, 12mm in inner diameter and 3mm in height material. The block is subjected to vacuum heat treatment at 550℃ for 1h, and the vacuum degree is ≤10 -3 Pa. Cold inlay a small piece of sintered block with epoxy resin, and polish its surface, use scanning electron microscope to take the cross-section of the block after heat treatment. figure 2 As shown, it can be seen that a similar honeycomb network core-shell structure is obtained in this embodiment, the core is pure iron powder, and the shell is nano-Mn 0.6 Zn 0.4 Fe 2 O 4 powder. Use the B-H analyzer to carry out the magnetic performance test, the sample performance obtained is shown in Table 3 (Bmax=50mT), and the effective permeability varies with the test frequency as Figure 4 Shown. by Figure 4 It can be seen that the effective magnetic permeability of the magnetic powder core block varies little with frequency and remains basically constant, but the magnetic permeability is slightly lower than that of the composite magnetic powder core made by adding nano-ferroferric oxide powder, and higher than 75μm water A composite magnetic powder core made by atomizing pure Fe powder. Using the MATS-2010SD soft magnetic DC test system to test the DC performance, the maximum saturation magnetic induction intensity Bs value of the sample is 1.56T, the coercivity Hc is 8.35 Oe, and the maximum permeability is 210.

[0048] table 3

[0049] Frequency/kHz