Preparation method of a high-strength and low-loss soft magnetic composite material

Abstract

The present invention relates to a method for preparing a soft magnetic composite material with high strength and low loss, belonging to the technical field of soft magnetic composite materials. The above preparation method includes: Step 1: uniformly mix soft magnetic powder with a lubricant; Step 2: press and mold the mixed powder by a bidirectional pressing method to obtain a specimen; Step 3: perform annealing treatment on the above specimen; Step 4: after annealing the specimen, keep it at 110 - 130 °C for 20 - 30 min, then soak it in a magnetic powder adhesive solution for infiltration for 45 - 60 min; then take it out and air dry naturally; Step 5: cure the specimen obtained in Step 4 at 210 - 230 °C for 50 - 60 min to obtain a soft magnetic composite material with high strength and low loss. The present invention successfully prepares a soft magnetic composite material with high strength, low loss and excellent magnetic properties by adjusting the addition amount and addition sequence of the lubricant and screening the process conditions of the infiltration step.

Description

Technical Field

[0001] The present invention relates to the technical field of soft magnetic composite materials, and specifically provides a preparation method for a soft magnetic composite material with high strength and low loss. Background Art

[0002] The factors affecting the performance of soft magnetic composite materials mainly include the density and strength of the formed parts. The density directly affects the magnetic properties of the soft magnetic composite materials, while the strength directly restricts the application range of the soft magnetic composite materials. Therefore, when improving the magnetic properties of soft magnetic composite materials, the factors of density and strength should be considered. In powder metallurgy, one way to increase density is to increase the pressing force. However, due to the limitation of the mold strength, the pressing force cannot be increased infinitely. On the other hand, the internal pores of the parts after annealing can be reduced by reducing the addition amount of the lubricant.

[0003] Previously, the inventor increased the density of the formed material by the method of double pressing and double annealing, and immersed the sample in a silane coupling agent for infiltration after the first annealing, so that the voids generated by annealing were filled with the silane coupling agent, further increasing its density, and to a certain extent increasing the strength of the sample, and the high-frequency loss was also low. However, for the high-strength requirements in special occasions, the soft magnetic composite materials prepared by the above method are still lacking. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a preparation method for a soft magnetic composite material with high strength and low loss. The present invention screens the lubricant, and through high-temperature infiltration and curing, improves the strength of the soft magnetic composite material, ensures that the components of the soft magnetic composite material are not damaged during the assembly process, and adopts an infiltration process for the annealed soft magnetic composite material to achieve higher strength and lower loss.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method for a soft magnetic composite material with high strength and low loss, including:

[0007] Step 1: Mix the soft magnetic powder and the lubricant evenly;

[0008] Step 2: Press the mixed powder into a shape to obtain a sample;

[0009] Step 3: Anneal the above sample;

[0010] Step 4: After annealing the sample, keep it at 110 - 130 °C for 20 - 30 min, then immerse it in a magnetic powder glue solution for infiltration for 45 - 60 min; then take it out and air dry it naturally;

[0011] Step 5: Cure the sample obtained in the above Step 4 in an atmosphere of 210 - 230°C for 50 - 60 min to obtain a high-strength and low-loss soft magnetic composite material.

[0012] Further, Step 1 is specifically as follows: First, uniformly mix the soft magnetic powder and zinc stearate; then add micronized wax and continue to mix uniformly.

[0013] Preferably, the addition amount of zinc stearate is 0.04% of the weight of the soft magnetic powder; the addition amount of micronized wax is 0.36% of the weight of the soft magnetic powder.

[0014] Preferably, the soft magnetic powder is the powder of Hoganas 130i5P and 700HR5P.

[0015] Further, in Step 2, the pressing method is double-sided pressing, the pressing pressure is 800 - 1200 Mpa, and the pressing time is 3 - 6 s.

[0016] Preferably, the pressing pressure is 900 MPa and the pressing time is 3 s.

[0017] Further, in Step 3, the annealing temperature is 600 - 700°C, the heat preservation time is 30 min, and the annealing atmosphere is nitrogen.

[0018] Further, in Step 4, the magnetic powder adhesive solution is an acetone solution of W-6C and W-6D magnetic powder adhesives.

[0019] Preferably, the weight ratio of acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1 - 1.8:0.2 - 1.

[0020] Preferably, the weight ratio of acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.6:0.4.

[0021] Since the soft magnetic composite material adopts an annealing process (temperature not higher than 700°C), during the annealing process, no sintering necks are formed between the soft magnetic particles, and the binding force between the soft magnetic particles is mainly due to the biting force between the soft magnetic particles, resulting in relatively low strength. In the present invention, by using a magnetic powder adhesive with a high-temperature curing effect, heating and curing the infiltrated magnetic powder adhesive, the binding force between the soft magnetic particles is made stronger and the strength is higher through the action of the magnetic powder adhesive. In addition, by comparing the infiltration strengths under different pressing forces, the present invention aims to improve the strength and reduce the loss. Since the higher the pressing force, the fewer and smaller the pores inside the sample, the less magnetic powder adhesive infiltrates, and the lower the strength; at the same time, the greater the pressing force, the greater the internal stress of the sample, and it is difficult to completely eliminate the internal stress during the annealing process. Therefore, reducing the pressing force will reduce the internal stress and thus reduce the loss.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] By reasonably proportioning zinc stearate and micronized wax and combining their addition processes, the present invention can well balance the powder properties of zinc stearate and the excellent lubricity of micronized wax during the forming process, resulting in a significant increase in the strength and density of the specimens. To further improve the strength of the soft magnetic composite material and ensure that the components of the soft magnetic composite material are not damaged during the assembly process, an infiltration process is adopted for the annealed soft magnetic composite material to achieve higher strength and lower losses. Specific embodiments

[0024] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to specific embodiments.

[0025] The reagents and materials used in the examples and comparative examples can be obtained through commercial channels without special instructions. Among them, the density of stearic acid is 1.095 g / cm 3 ; the melting point is 120 ± 5 °C, and the average particle size is 55 μm; the micronized wax is W-special micronized wax, and the density is 0.9 g / cm 3 ; the melting point is 90 - 140 °C, and the average particle size is 35 - 45 μm. The magnetic powder adhesive can be W-6C and W-6D magnetic powder adhesives produced by Chenghua Adhesive Industry Co., Ltd.

[0026] The present invention provides a method for preparing a high-strength and low-loss soft magnetic composite material, and the specific embodiments are as follows.

[0027] Example 1

[0028] A method for preparing a high-strength and low-loss soft magnetic composite material includes:

[0029] Step 1: Mix the soft magnetic powder and the lubricant evenly: First, mix the soft magnetic powder Hoganas 130i5P and zinc stearate evenly; then add micronized wax and continue to mix evenly; the addition amount of zinc stearate is 0.04% of the weight of the soft magnetic powder; the addition amount of micronized wax is 0.36% of the weight of the soft magnetic powder.

[0030] Step 2: Press and form the mixed powder by a two-way pressing method to obtain a specimen; the pressing pressure is 1000 Mpa, and the pressing time is 3 s.

[0031] Step 3: Anneal the above specimen; the annealing temperature is 650 °C, the holding time is 30 min, and the annealing atmosphere is nitrogen.

[0032] Step 4: After annealing the specimen at 120 °C for 25 min, soak it in the magnetic powder adhesive solution for infiltration for 50 min; then take it out and air-dry it naturally; the magnetic powder adhesive solution is an acetone solution of W-6C and W-6D magnetic powder adhesives; the weight ratio of the acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.6:0.4.

[0033] Step 5: Cure the specimen obtained in Step 4 above in an atmosphere of 220 °C for 50 min to obtain a high-strength and low-loss soft magnetic composite material.

[0034] Example 2

[0035] In Step 2 of this example, the pressing pressure is 800 MPa, and the other conditions are the same as those in Example 1.

[0036] Example 3

[0037] In Step 2 of this example, the pressing pressure is 900 MPa, and the other conditions are the same as those in Example 1.

[0038] Example 4

[0039] In Step 2 of this example, the pressing pressure is 1100 MPa, and the other conditions are the same as those in Example 1.

[0040] Example 5

[0041] In Step 2 of this example, the pressing pressure is 1200 MPa, and the other conditions are the same as those in Example 1.

[0042] Example 6

[0043] In Step 4 of this example, the weight ratio of the acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1:1, and the other conditions are the same as those in Example 1.

[0044] Example 7

[0045] In Step 4 of this example, the weight ratio of the acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.2:0.8, and the other conditions are the same as those in Example 1.

[0046] Example 8

[0047] In Step 4 of this example, the weight ratio of the acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.4:0.6, and the other conditions are the same as those in Example 1.

[0048] Example 9

[0049] In Step 4 of this example, the weight ratio of the acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.8:0.2, and the other conditions are the same as those in Example 1.

[0050] Example 10

[0051] A preparation method of a high-strength and low-loss soft magnetic composite material, comprising:

[0052] Step 1: Mix the soft magnetic powder and the lubricant evenly;

[0053] First, evenly mix the soft magnetic powder Hoganas 700HR5P and zinc stearate; then add micronized wax and continue to mix evenly; the addition amount of zinc stearate is 0.04% of the weight of the soft magnetic powder; the addition amount of micronized wax is 0.36% of the weight of the soft magnetic powder.

[0054] Step 2: Press the mixed powder into a shape by a two-way pressing method to obtain a specimen; the pressing pressure is 900 Mpa and the pressing time is 4 s.

[0055] Step 3: Anneal the above specimen; the annealing temperature is 600 °C, the holding time is 30 min, and the annealing atmosphere is nitrogen.

[0056] Step 4: After keeping the annealed specimen at 110 °C for 30 min, soak it in the magnetic powder adhesive solution for infiltration for 60 min; then take it out and air-dry it naturally; the magnetic powder adhesive solution is an acetone solution of W-6C and W-6D magnetic powder adhesives; the weight ratio of acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.6:0.4.

[0057] Step 5: Cure the specimen obtained in Step 4 above at 230 °C for 50 min to obtain a high-strength and low-loss soft magnetic composite material.

[0058] Example 11

[0059] A preparation method of a high-strength and low-loss soft magnetic composite material, comprising:

[0060] Step 1: Mix the soft magnetic powder and the lubricant evenly;

[0061] First, evenly mix the soft magnetic powder Hoganas 130i5P and zinc stearate; then add micronized wax and continue to mix evenly; the addition amount of zinc stearate is 0.04% of the weight of the soft magnetic powder; the addition amount of micronized wax is 0.36% of the weight of the soft magnetic powder.

[0062] Step 2: Press the mixed powder into a shape by a two-way pressing method to obtain a specimen; the pressing pressure is 800 Mpa and the pressing time is 6 s.

[0063] Step 3: Anneal the above specimen; the annealing temperature is 600 - 700 °C, the holding time is 30 min, and the annealing atmosphere is nitrogen.

[0064] Step 4: After annealing the specimen at 130°C for 20 min, soak it in the magnetic powder adhesive solution for infiltration for 45 min; then take it out and air-dry it naturally; the magnetic powder adhesive solution is an acetone solution of W-6C and W-6D magnetic powder adhesives; the weight ratio of the acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.6:0.4.

[0065] Step 5: Cure the specimen obtained in Step 4 above in an atmosphere at 210°C for 60 min to obtain a high-strength and low-loss soft magnetic composite material.

[0066] To further illustrate the beneficial effects of the present invention, due to limited space, only Comparative Examples 1 and 11 are taken as examples to construct the following comparative examples.

[0067] Comparative Example 1

[0068] In Step 1 of this comparative example, the soft magnetic powder is mixed with zinc stearate having a mass of 4% of the weight of the soft magnetic powder, and the remaining conditions are the same as those in Example 1.

[0069] Comparative Example 2

[0070] In Step 1 of this comparative example, the soft magnetic powder is mixed with micronized wax having a mass of 4% of the weight of the soft magnetic powder, and the remaining conditions are the same as those in Example 1.

[0071] Comparative Example 3

[0072] In Step 1 of this comparative example, first mix zinc stearate and micronized wax, and then mix them evenly with the soft magnetic powder. The remaining conditions are the same as those in Example 1.

[0073] Comparative Example 4

[0074] In Step 1 of this comparative example, first mix the micronized wax with the soft magnetic powder, and then add zinc stearate for mixing. The remaining conditions are the same as those in Example 1.

[0075] Comparative Example 5

[0076] In Step 4 of this comparative example, the magnetic powder adhesive solution is a mixed solution of acetone and W-6C magnetic powder adhesive with a weight ratio of 5:1, and the remaining conditions are the same as those in Example 1.

[0077] Comparative Example 6

[0078] In Step 4 of this comparative example, the magnetic powder adhesive solution is a mixed solution of acetone and W-6C magnetic powder adhesive with a weight ratio of 5:2, and the remaining conditions are the same as those in Example 1.

[0079] Comparative Example 7

[0080] In Step 4 of this comparative example, the magnetic powder adhesive solution is a mixed solution of acetone and W-6C magnetic powder adhesive with a weight ratio of 2:1, and the remaining conditions are the same as those in Example 1.

[0081] Comparative Example 8

[0082] In Step 4 of this comparative example, the magnetic powder adhesive solution is a mixed solution of acetone and W-6C magnetic powder adhesive with a weight ratio of 5:3, and the other conditions are the same as those in Example 1.

[0083] Comparative Example 9

[0084] In Step 4 of this comparative example, the magnetic powder adhesive solution is a mixed solution of acetone and W-6D magnetic powder adhesive with a weight ratio of 5:1, and the other conditions are the same as those in Example 1.

[0085] Comparative Example 10

[0086] In Step 4 of this comparative example, the magnetic powder adhesive solution is a mixed solution of acetone and W-6D magnetic powder adhesive with a weight ratio of 5:2, and the other conditions are the same as those in Example 1.

[0087] Comparative Example 11

[0088] In Step 4 of this comparative example, the magnetic powder adhesive solution is a mixed solution of acetone and W-6D magnetic powder adhesive with a weight ratio of 2:1, and the other conditions are the same as those in Example 1.

[0089] Comparative Example 12

[0090] Steps 4-5 of this comparative example are omitted, and the other conditions are the same as those in Example 1.

[0091] Comparative Example 13

[0092] Step 4 of this comparative example: After annealing the specimen and keeping it at 120°C for 25 minutes, immerse it in KBM-403 silane coupling agent for infiltration for 50 minutes; then take it out and air dry it naturally; the other conditions are the same as those in Example 1.

[0093] Comparative Example 14

[0094] Step 4 of this comparative example: Immerse the annealed specimen in the magnetic powder adhesive solution for infiltration for 50 minutes; then take it out and air dry it naturally; the magnetic powder adhesive solution is an acetone solution of W-6C and W-6D magnetic powder adhesives; the weight ratio of acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.6:0.4; the other conditions are the same as those in Example 1.

[0095] Comparative Example 15

[0096] Step 5 of this comparative example is: Place the specimen obtained in the above Step 4 at room temperature for 24 hours, and the other conditions are the same as those in Example 1.

[0097] Comparative Example 16

[0098] In Step 1 of this comparative example, the micronized wax was first mixed with the soft magnetic powder, and then zinc stearate was added for mixing. The other conditions were the same as those in Example 11.

[0099] Comparative Example 17

[0100] In Step 4 of this comparative example, the magnetic powder adhesive solution was a mixed solution of acetone and W-6C magnetic powder adhesive with a weight ratio of 5:2. The other conditions were the same as those in Example 11.

[0101] Comparative Example 18

[0102] In Step 4 of this comparative example, the magnetic powder adhesive solution was a mixed solution of acetone and W-6D magnetic powder adhesive with a weight ratio of 5:2. The other conditions were the same as those in Example 11.

[0103] Comparative Example 19

[0104] Step 4 of this comparative example: After annealing the specimen at 120 °C for 25 min, it was immersed in KBM-403 silane coupling agent for infiltration for 50 min; then taken out and air-dried naturally; the other conditions were the same as those in Example 11.

[0105] Comparative Example 20

[0106] Step 5 of this comparative example was: The specimen in Step 4 above was placed at room temperature for 24 h, and the other conditions were the same as those in Example 11.

[0107] The properties of the soft magnetic composites prepared in the above Examples 1-11 and Comparative Examples 1-20 were tested, and the results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] As can be seen from the data in the above table, compared with Comparative Examples 1-4, with the lubricant addition amount and addition sequence of the present invention, the B S and μ max of the obtained soft magnetic composites are both improved, and the loss is reduced to a certain extent. Moreover, the strength of the soft magnetic composite of the present invention is the highest, reaching 145 MPa. Compared with zinc stearate, the strength is increased by 83%, and compared with micronized wax, the strength is increased by 79%; the density of the present invention can reach 7.48 g / cm 3 , compared with zinc stearate, the density is increased by 1.5%, and compared with W-special micronized wax, the density is increased by 0.9%. After adjusting the addition sequence of zinc stearate and micronized wax, the strength and other properties of the prepared soft magnetic composites are reduced, and the loss increases.

[0112] By comparison, when the pressing force is 900 MPa, the comprehensive performance is better. When it is 800 MPa, B S and the magnetic permeability decrease significantly. Compared with 1000 MPa, the magnetic permeability decreases by 4% at 800 MPa, while it only decreases by 1% at 900 MPa compared with 1000 MPa. The strength increases by 7%, and the loss decreases by 1.3%. This is mainly because the pressure decreases, the internal voids increase, and more infiltration agent can be absorbed. At the same time, the internal stress of the soft magnetic composite material sample decreases with the decrease of pressure, and the internal stress can be better eliminated through annealing. At the same time, the infiltrated solvent has insulation, reducing the eddy current loss.

[0113] From Comparative Examples 5-8, it can be seen that as the mass of the W-6C magnetic powder adhesive increases, the strength of the soft magnetic composite material increases. When it exceeds 5:2, the increase amplitude of the strength slows down. At the same time, comparing B S and the maximum magnetic permeability μ max it is found that as the mass fraction of the W-6C magnetic powder adhesive increases, the magnetic permeability and B S decrease significantly, and the power consumption also shows a downward trend with the increase of the ratio. At this time, compared with the non-infiltrated Comparative Example (12), the strength is increased by 1.8 times, and the magnetic permeability and B S slightly decrease, but the change is not obvious, and the power consumption also decreases.

[0114] From Comparative Examples 9-11, it can be seen that compared with the influence of the W-6C magnetic powder adhesive on the strength and electromagnetic properties, the W-6D magnetic powder adhesive shows higher strength. At the same time, the power consumption is lower relative to W-6C, which is related to the stronger insulation of W-6D, reducing the eddy current loss of the soft magnetic composite material. However, the increase of W-6D has a greater impact on B S and the maximum magnetic permeability μ max .

[0115] Considering the performance of W-6C and W-6D comprehensively, the obtained mixing ratio of the magnetic powder adhesive makes the magnetic properties, strength and loss of the prepared soft magnetic composite material in a relatively optimal state. By comparison, the comprehensive performance of the 5:1.6:0.4 mixing ratio is relatively optimal.

[0116] Compared with the silane coupling agent used for infiltration (Comparative Example 13), the performance of the present invention is also improved in all aspects. Compared with the previous experiments of the inventor (CN110947956A), there are significant differences in the infiltration principle. The previous experiments mainly simply filled the internal pores of the sample. However, due to the large pressing force, it is difficult for the bonding parts between iron powders to be infiltrated, and only the bonding force is formed at the pores of the iron powders. However, due to the introduction of impurities, the loss increases. The infiltration of the present invention reduces the pressing force, forming gaps between iron powders, and the infiltrated substances can completely cover the entire iron powder. On the one hand, it can further improve the strength, and on the other hand, it increases the insulation between iron powder particles, thereby reducing the loss.

[0117] In Comparative Example 14, the specimen was not heated before infiltration, resulting in a reduced infiltration effect. Comparative Example 15 was cured at room temperature, and the curing effect was also low. In contrast, the present invention uses high-temperature curing, which requires pre-heating the specimen and then performing infiltration. After infiltration, high-temperature curing is still required to obtain a soft magnetic composite material with high strength, low loss, and excellent magnetic properties.

[0118] Comparing Example 11 with Comparative Examples 16 - 20, it can be seen that the soft magnetic composite materials obtained by the method of the present invention using soft magnetic powders of different models also have relatively high strength and low loss, and all aspects of the magnetic properties are also excellent.

[0119] In summary, the present invention successfully prepares a soft magnetic composite material with high strength, low loss, and excellent magnetic properties by adjusting the addition amount and addition sequence of the lubricant and screening the process conditions of the infiltration step.

[0120] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Preparation method of a high-strength and low-loss soft magnetic composite material, characterized in that, it includes: Step 1: Mix the soft magnetic powder and the lubricant evenly: First, mix the soft magnetic powder and zinc stearate evenly; then add micronized wax and continue to mix evenly; the addition amount of zinc stearate is 0.04% of the weight of the soft magnetic powder; the addition amount of micronized wax is 0.36% of the weight of the soft magnetic powder; Step 2: Compress and form the mixed powder in two directions to obtain a specimen; the pressing pressure is 900 Mpa and the pressing time is 3 s; Step 3: Anneal the above specimen; the annealing temperature is 650 °C, the holding time is 30 min, and the annealing atmosphere is nitrogen; Step 4: After the annealed specimen is held at 120 °C for 25 min, soak it in the magnetic powder adhesive solution for infiltration for 50 min; then take it out and air dry naturally; the magnetic powder adhesive solution is an acetone solution of W-6C and W-6D magnetic powder adhesives; the weight ratio of acetone, W-6C magnetic powder adhesive, and W-6D magnetic powder adhesive is 5:1.6:0.4; Step 5: Cure the specimen in step 4 above at 220 °C for 50 min to obtain a high-strength and low-loss soft magnetic composite material.

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