CN105344993A - Method for preparing iron-silicon-aluminum soft magnetic powder core through warm-pressing - Google Patents

Abstract

The invention discloses a method for preparing an iron-silicon-aluminum soft magnetic powder core through warm-pressing. The method comprises the following steps that (1) initial soft magnetic alloy powder is subjected to passivating treatment through a passivator, and drying is conducted; (2) the dried soft magnetic alloy powder is evenly mixed with a binder; (3) the mixed powder is dried and sieved, and then an insulator is added for mixing coating; (4) the coated soft magnetic alloy powder is mixed with lubricant, the mixture is put into a die, then pressurization and heating are conducted simultaneously, and warm-pressing forming is conducted; and (5) the warm-pressing formed magnetic powder core is subjected to annealing treatment. The initial soft magnetic alloy powder comprises, by weight, 8.5%-10.5% of silicon, 4.5%-6.5% of aluminum, and the balance iron. The lubricant in the step (4) is the mixture of zinc stearate and polyethylene glycol. According to the method, the density and the magnetic conductivity of the prepared soft magnetic powder core can be effectively improved, and the magnetic loss is significantly reduced.

Description

A method for preparing sendust soft magnetic powder core by warm pressing

technical field

The invention relates to the field of powder metallurgy manufacturing of metal materials, in particular to a method for preparing a sendust soft magnetic powder core and a soft magnetic powder core prepared by the method.

Background technique

Magnetic powder core is a new type of soft magnetic functional material with special function of magnetoelectric conversion, which is made by mixing and pressing soft magnetic alloy powder and insulating medium through powder metallurgy process. Because the particle size of the magnetic powder is very small, and the surface of the ferromagnetic powder particles is evenly coated with a layer of insulating dielectric film, which improves the resistivity of the magnetic powder core and hinders the eddy current between the magnetic powder, so the eddy current loss is very low, suitable for relatively High frequency applications (above 20kHz). In addition, the magnetic powder core also has the advantages of high saturation magnetic induction, good frequency characteristics, low coercive force, constant magnetic permeability and temperature stability, etc., making the magnetic powder core as an inductance filter, and the choke coil is widely used in electronic communications. , radar, power switch and other fields, has become an important part of soft magnetic materials.

The composition of sendust magnetic powder core is Fe-(8~13%)Si-(4~7%)Al, which is a new type of soft magnetic material with magnetoelectric conversion function. Because of its superior soft magnetic properties and appropriate price, it is widely used in electronic devices such as pulse transformers, regression transformers, line noise filters, and energy storage inductors. At present, sendust magnetic powder cores are in the stage of large-scale application and further development.

Generally speaking, the greater the pressure, the higher the density of the compact, and the greater the magnetic permeability of the magnetic powder. However, increasing the pressure has a limit to increase the density of the magnetic powder core. Excessive pressure will also cause the insulation layer to rupture, thereby reducing the insulation effect.

Metal powder warm pressing forming technology is to transform the traditional powder metallurgy press, adopt special powder heating, powder conveying and mold heating system, and heat the mixed powder mixed with special lubricant and binder for warm pressing to a specific The temperature is pressed, and then sintered by the traditional process to obtain a product with higher density and performance. At present, warm pressing is mainly used to prepare structural materials to improve mechanical properties, and it is rare to apply it to the development of powder magnetic materials to improve the properties of soft magnetic powder cores. In terms of published patents, only Zhejiang University "a method for preparing metal soft magnetic composite materials by warm pressing (application number CN201410246527.2)" and Guangdong University of Technology "a method for preparing amorphous soft magnetic powder cores ( Application number CN201410013455.7)". Zhu Tao (Zhu Tao. Research on powder warm pressing composite lubricant and its application in the preparation of Fe-Si soft magnetic materials [D]. Hefei: Hefei University of Technology, 2012) studied the application of warm pressing to Fe-Si soft magnetic materials. The effect of the alloy on its structure and mechanical properties, using a mixture of amine-based polymers, stearate and glycol-based polymers as a warm-pressure lubricant. H.Shokrollahi et al. (H.Shokrollahi.etal..JournalofMagnetismandMagneticMaterials.2007,313:182-186) studied the impact of pressing parameters at room temperature on the magnetic properties of the magnetic powder core of soft magnetic composite materials based on pure iron powder. The lubricant used is Zinc stearate, the results show that with the increase of the pressing pressure, the density of the powder core increases, the magnetic permeability and the magnetic induction intensity increase, but at the same time, the defects such as dislocations and internal stress introduced by the pressure increase also increase, so The coercive force also increased.

Soft magnetic materials have been widely used in the field of power electronics. At present, most of the alloy application products are wound into magnetic cores with cold-quenched thin strips and then annealed. However, the loss characteristics of the high-frequency band limit the application of the thin strip core, and the thin strip after heat treatment is brittle. In the industrial field, in most cases, it is necessary to use this material to make special shapes to meet various needs. On the premise of not compromising the excellent soft magnetic properties of this material, the loss value of the magnetic core should be significantly reduced. This goal can be achieved by crushing the alloy strip into magnetic powder and pressing it into a magnetic powder core. At present, there is no report on the preparation of FeSiAl soft magnetic powder cores by warm pressing.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a soft magnetic powder core by using a warm pressing process based on the above background; at the same time, the present invention also provides a soft magnetic powder core prepared by the method, the soft magnetic powder core It has high magnetic permeability and low magnetic loss.

In order to achieve the above object, the technical solution adopted by the present invention is: a method for preparing sendust soft magnetic powder core by warm pressing, comprising the following steps:

(1) Utilize passivating agent to carry out passivation treatment to initial soft magnetic alloy powder, dry;

(2) uniformly mixing the dried soft magnetic alloy powder and binder in step (1);

(3) Dry and sieve the mixed powder obtained in step (2), and then add an insulating agent to mix and coat;

(4) Mix the soft magnetic alloy powder coated in step (3) with a lubricant, and put it into a mould, then heat while pressurizing, and press to form under warm pressure;

(5) carrying out annealing treatment to the magnetic powder core formed by warm pressing in step (4);

The weight percent content of the initial soft magnetic alloy powder is: 8.5-10.5% of silicon, 4.5-6.5% of aluminum, and the balance is iron;

The lubricant in the step (4) is a mixture of zinc stearate and polyethylene glycol.

In the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, special lubricants are used for warm pressing, which can greatly improve the magnetic permeability, magnetic loss and other soft magnetic properties of the prepared magnetic powder cores, and further improve the soft magnetic powder cores. It is expected to achieve considerable economic benefits in the short term.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the weight percent content of the initial soft magnetic alloy powder is: 9.9% of silicon, 5.5% of aluminum, and the balance is iron. When the initial soft magnetic alloy powder of this composition is used, the FeSiAl soft magnetic powder core is prepared, which has higher magnetic permeability and higher cost performance. The soft magnetic alloy powder of the present invention can be obtained by means of existing technologies, and can be purchased directly from the market. In the present invention, the soft magnetic alloy powder is preferably but not limited to the soft magnetic alloy powder of the above-mentioned composition, and the soft magnetic alloy powder of the above-mentioned composition can be obtained from a wide range of sources and has relatively high cost performance.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, in the lubricant in the step (4), the mass ratio of zinc stearate to polyethylene glycol is (0.02～5 ):1. As a more preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, in the lubricant of the step (4), the mass ratio of zinc stearate to polyethylene glycol is (3～ 1): 2. As the most preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, in the lubricant of the step (4), the mass ratio of zinc stearate to polyethylene glycol is 2:3 . The method for preparing sendust soft magnetic powder cores by warm pressing in the present invention adopts a special lubricant, that is, the lubricant is composed of two substances, namely zinc stearate and polyethylene glycol, and their The mass ratio is (0.02～5):1. The inventors of the present application have found through a lot of research that when the lubricant uses the specific ratio of zinc stearate and polyethylene glycol, the sendust soft magnetic powder core prepared by the method of the present invention has a relatively high High magnetic permeability and very low magnetic loss. Especially when the mass ratio of zinc stearate to polyethylene glycol in the lubricant is 2:3, the obtained sendust soft magnetic powder core has the highest magnetic permeability and the lowest magnetic loss.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the mass ratio of the lubricant to the initial soft magnetic alloy powder in the step (4) is 0.4-2%. As a more preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the mass ratio of the lubricant to the initial soft magnetic alloy powder in the step (4) is 0.5-1.5%. The inventors of the present application have found through research that the performance of the soft magnetic powder core obtained in this application is not only related to the ratio of zinc stearate and polyethylene glycol in the lubricant, but also related to the amount of lubricant added. The inventors have found through experiments that when the mass ratio of the lubricant to the initial soft magnetic alloy powder is 0.4 to 2%, the resulting soft magnetic powder core has higher density, magnetic permeability and lower magnetic loss; especially When the mass ratio of the lubricant to the initial soft magnetic powder core is 0.5-1.5%, the obtained soft magnetic powder core has better density, magnetic permeability and lower magnetic loss.

As a preferred embodiment of the method for preparing the soft magnetic powder core of sendust by warm pressing in the present invention, the binding agent in the step (2) is a mixture of sodium silicate and high temperature resistant organic silicon resin; the step ( 3) The insulating agent in is nano silicon dioxide.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, in the binder of the step (2), the mass ratio of sodium silicate and high temperature resistant organic silicon resin is (4～ 1): 2. As a more preferred embodiment of the method for preparing sendust soft magnetic powder core by warm pressing according to the present invention, in the binder of the step (2), the mass ratio of sodium silicate and high temperature resistant silicone resin is 3: 2. In the preparation method of the sendust soft magnetic powder core of the present invention, the binder is composed of two specific substances, i.e. sodium silicate and high temperature resistant organic silicic acid resin, and the mass ratio of the two is (4 ～1): 2. The inventors of the present application have found through a lot of research that when the binder is composed of sodium silicate and high temperature resistant silicone resin in a specific ratio, the lubricant and process conditions in combination with the specific ratio , can obtain the sendust soft magnetic powder core with high magnetic permeability and very low magnetic loss.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the mass ratio of the binder in the step (2) to the initial soft magnetic alloy powder is 1 to 2%; In step (3), the mass ratio of the insulating agent to the initial soft magnetic alloy powder is 0-0.4%. As a more preferred embodiment of the method for preparing sendust soft magnetic powder core by warm pressing in the present invention, the mass ratio of the binder in the step (2) to the initial soft magnetic alloy powder is 1.5%; the step (3) The mass ratio of the insulating agent to the initial soft magnetic alloy powder is 0.1-0.4%. As a more preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the mass ratio of the insulating agent to the initial soft magnetic alloy powder in the step (3) is 0.2%.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the passivating agent used in the step (1) is a phosphoric acid solution, and the mass percent concentration of the phosphoric acid solution is 0.4- 3% (the rest is water), the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is (0.5-1.5):1. When the concentration of the passivating agent in the phosphoric acid solution is very low, the thickness of the phosphating film formed on the surface of the powder particles is very thin, and the passivation effect is not complete. With the increase of passivating agent concentration and the deepening of passivation degree, a complete and uniform phosphating film can be formed on the surface of powder particles. However, when the concentration of the passivating agent in the phosphoric acid solution is too high, the thickness of the phosphating film is too large and it is easy to cause cracking and falling off. As a more preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the passivating agent adopted in the step (1) is a phosphoric acid solution, and the mass percent concentration of the phosphoric acid solution is 0.7 %. When the mass percent concentration of the phosphoric acid solution passivator is 0.7%, the best film-forming state can be achieved.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the pressing pressure of warm pressing in step (4) is 500-1200 MPa, and the pressing temperature is 60-150°C. If the pressing pressure is too small, the density of the magnetic powder core is not high enough and the performance is not good. When the pressing pressure is too high, the mold is easily damaged. When the pressing temperature is too low, the solid lubricant has not yet melted, so the effect of increasing the temperature and pressure density is not obvious; when the temperature and pressure temperature is too high, the viscosity of the lubricating film decreases, resulting in direct contact between powder particles, resulting in a decrease in density, and high internal stress. It is beneficial to improve the soft magnetic properties. In the preparation method of the soft magnetic powder core of the present invention, in the warm-pressing process, the pressing pressure and the pressing temperature are used to obtain a higher density at a lower pressing pressure at the warm-pressing temperature, and the obtained The internal stress of the magnetic powder core is low, which is beneficial to obtain higher magnetic permeability and lower loss. In addition, it can reduce the pressing pressure, reduce the mold loss, and the economic effect is remarkable.

As a preferred embodiment of the method for preparing sendust soft magnetic powder cores by warm pressing in the present invention, the annealing temperature of the annealing treatment in the step (5) is 550-750° C., and the annealing time is 0.5-1.5 hours. If the annealing temperature is low and the time is short, the effect of eliminating internal stress is not obvious, which is not conducive to improving the magnetic properties; if the annealing temperature is too high, the magnetic powder core is easy to oxidize and deteriorate, consumes energy, and may also cause damage to the insulating layer between powder particles. Deterioration of magnetic properties.

At the same time, the present invention also provides a sendust soft magnetic powder core with higher magnetic permeability and lower magnetic loss. To achieve this purpose, the technical solution adopted by the present invention is: a sendust soft magnetic powder core , which was prepared as described above.

The preparation method of the sendust soft magnetic powder core of the present invention applies the new technology of powder metallurgy warm pressing to the preparation of amorphous soft magnetic powder core, and finally selects the specific lubricant and other feeding options through a large number of experiments And the combination of feeding sequence, pressing pressure, pressing temperature, etc., the method technical scheme composed of these overall combination, the prepared amorphous soft magnetic magnetic powder core has higher density and lower internal stress, and the obtained magnetic powder core has higher Magnetic permeability and very low magnetic loss. The preparation method of the soft magnetic magnetic powder core of the present invention, compared with the existing soft magnetic magnetic powder core preparation technology, the inventive method can obtain higher density with a smaller pressing pressure under the warm-pressing temperature, and the magnetic powder core The stress is low, which is conducive to the movement of the magnetic domain wall and the rotation of the magnetic domain, and is beneficial to obtain higher magnetic permeability and lower loss. Moreover, the method of the invention can reduce pressing pressure, reduce mold loss, and has significant economic effect.

detailed description

In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific examples.

In the following examples, the weight percentages of the initial soft magnetic alloy powder are: 8.5-10.5% silicon, 4.5-6.5% aluminum, and iron as the balance. More preferably, in the following examples, the weight percentages of the initial soft magnetic alloy powder are: 9.9% silicon, 5.5% aluminum, and iron as the balance.

Example 1

An embodiment of the method for preparing sendust soft magnetic powder core by warm pressing in the present invention, the preparation method of the soft magnetic powder core described in this embodiment comprises the following steps:

(1) Passivate the initial soft magnetic alloy powder with a phosphoric acid solution with a mass percent concentration of 0.4%, and dry it; the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is 0.5:1;

(2) The soft magnetic alloy powder after step (1) is dried is mixed evenly with binding agent, and the mass ratio of described binding agent and initial soft magnetic alloy powder is 2%, and described binding agent is sodium silicate, A mixture of high temperature resistant silicone resin, and the mass ratio of the sodium silicate and high temperature resistant silicone resin is 2:1;

(3) Dry and sieve the mixed powder obtained in step (2), then add nano silicon dioxide to mix and coat, the mass ratio of the nano silicon dioxide to the initial soft magnetic alloy powder is 0.1%;

(4) Mix the soft magnetic alloy powder coated in step (3) with a lubricant, put it into a mold, and then heat it while pressurizing, and press it under warm pressure at a pressure of 500MPa and a temperature of 150°C Forming; the mass ratio of the lubricant to the initial soft magnetic alloy powder is 1%, the lubricant is a mixture of zinc stearate and polyethylene glycol, and the mass ratio of the zinc stearate and polyethylene glycol The ratio is 0.02:1;

(5) Perform annealing treatment on the magnetic powder core formed by warm pressing in step (4), the annealing temperature is 550°C, and the annealing time is 0.5h.

Example 2

An embodiment of the method for preparing sendust soft magnetic powder core by warm pressing in the present invention, the preparation method of the soft magnetic powder core described in this embodiment comprises the following steps:

(1) Passivate the initial soft magnetic alloy powder with a phosphoric acid solution with a mass percent concentration of 1%, and dry it; the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is 0.6:1;

(2) The soft magnetic alloy powder after step (1) is dried is mixed evenly with binding agent, and the mass ratio of described binding agent and initial soft magnetic alloy powder is 1.8%, and described binding agent is sodium silicate, A mixture of high temperature resistant silicone resin, and the mass ratio of the sodium silicate and high temperature resistant silicone resin is 3:2;

(3) Dry and sieve the mixed powder obtained in step (2), then add nano silicon dioxide to mix and coat, the mass ratio of the nano silicon dioxide to the initial soft magnetic alloy powder is 0.15%;

(4) Mix the soft magnetic alloy powder coated in step (3) with lubricant, and put it into the mold, then heat it while pressurizing, and press it under warm pressure at a pressure of 800MPa and a temperature of 90°C Shaping; the mass ratio of the lubricant to the initial soft magnetic alloy powder is 2%, the lubricant is a mixture of zinc stearate and polyethylene glycol, and the mass ratio of the zinc stearate and polyethylene glycol The ratio is 0.4:1;

(5) Perform annealing treatment on the magnetic powder core formed by warm pressing in step (4), the annealing temperature is 600°C, and the annealing time is 0.6h.

Example 3

An embodiment of the method for preparing sendust soft magnetic powder core by warm pressing in the present invention, the preparation method of the soft magnetic powder core described in this embodiment comprises the following steps:

(1) Passivate the initial soft magnetic alloy powder with a phosphoric acid solution with a mass percent concentration of 2%, and dry it; the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is 0.8:1;

(2) The soft magnetic alloy powder after step (1) is dried is mixed evenly with binder, and the mass ratio of described binder and initial soft magnetic alloy powder is 1.6%, and described binder is sodium silicate, A mixture of high temperature resistant silicone resin, and the mass ratio of the sodium silicate and high temperature resistant silicone resin is 3:2;

(3) Dry and sieve the mixed powder obtained in step (2), then add nano silicon dioxide to mix and coat, the mass ratio of the nano silicon dioxide to the initial soft magnetic alloy powder is 0.2%;

(4) Mix the soft magnetic alloy powder coated in step (3) with lubricant, and put it into the mold, then heat it while pressurizing, and press it under warm pressure at a pressure of 600MPa and a temperature of 120°C Forming; the mass ratio of the lubricant to the initial soft magnetic alloy powder is 0.5%, the lubricant is a mixture of zinc stearate and polyethylene glycol, and the mass ratio of the zinc stearate and polyethylene glycol The ratio is 1:2;

(5) Perform annealing treatment on the magnetic powder core formed by warm pressing in step (4), the annealing temperature is 630° C., and the annealing time is 1 h.

Example 4

An embodiment of the method for preparing sendust soft magnetic powder core by warm pressing in the present invention, the preparation method of the soft magnetic powder core described in this embodiment comprises the following steps:

(1) Passivate the initial soft magnetic alloy powder with a phosphoric acid solution with a mass percent concentration of 0.7%, and dry it; the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is 1:1;

(2) The soft magnetic alloy powder after step (1) is dried is mixed evenly with binding agent, and the mass ratio of described binding agent and initial soft magnetic alloy powder is 1.5%, and described binding agent is sodium silicate, A mixture of high temperature resistant silicone resin, and the mass ratio of the sodium silicate and high temperature resistant silicone resin is 3:2;

(3) Dry and sieve the mixed powder obtained in step (2), then add nano silicon dioxide to mix and coat, the mass ratio of the nano silicon dioxide to the initial soft magnetic alloy powder is 0.2%;

(4) Mix the soft magnetic alloy powder coated in step (3) with lubricant, and put it into the mold, then heat it while pressurizing, and press it under warm pressure at a pressure of 1100MPa and a temperature of 100°C Forming; the mass ratio of the lubricant to the initial soft magnetic alloy powder is 1.3%, the lubricant is a mixture of zinc stearate and polyethylene glycol, and the mass ratio of the zinc stearate and polyethylene glycol The ratio is 2:3;

(5) Perform annealing treatment on the magnetic powder core formed by warm pressing in step (4), the annealing temperature is 680° C., and the annealing time is 1 h.

Example 5

An embodiment of the method for preparing sendust soft magnetic powder core by warm pressing in the present invention, the preparation method of the soft magnetic powder core described in this embodiment comprises the following steps:

(1) Passivate the initial soft magnetic alloy powder with a phosphoric acid solution with a mass percent concentration of 3%, and dry it; the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is 1.2:1;

(2) The soft magnetic alloy powder after step (1) is dried is mixed evenly with binder, and the mass ratio of described binder and initial soft magnetic alloy powder is 1.2%, and described binder is sodium silicate, A mixture of high temperature resistant silicone resin, and the mass ratio of the sodium silicate and high temperature resistant silicone resin is 2:3;

(3) Dry and sieve the mixed powder obtained in step (2), then add nano silicon dioxide to mix and coat, the mass ratio of the nano silicon dioxide to the initial soft magnetic alloy powder is 0.3%;

(4) Mix the soft magnetic alloy powder coated in step (3) with a lubricant, put it into a mold, and then heat it while pressurizing, and press it under warm pressure at a pressure of 1000MPa and a temperature of 80°C Forming; the mass ratio of the lubricant to the initial soft magnetic alloy powder is 1.5%, the lubricant is a mixture of zinc stearate and polyethylene glycol, and the mass ratio of the zinc stearate and polyethylene glycol The ratio is 3:2;

(5) Perform annealing treatment on the magnetic powder core formed by warm pressing in step (4), the annealing temperature is 700°C, and the annealing time is 1.3h.

Example 6

An embodiment of the method for preparing sendust soft magnetic powder core by warm pressing in the present invention, the preparation method of the soft magnetic powder core described in this embodiment comprises the following steps:

(1) Passivate the initial soft magnetic alloy powder with a phosphoric acid solution with a mass percent concentration of 1.5%, and dry it; the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is 1.5:1;

(2) The soft magnetic alloy powder after step (1) is dried is mixed evenly with binding agent, and the mass ratio of described binding agent and initial soft magnetic alloy powder is 1%, and described binding agent is sodium silicate, A mixture of high temperature resistant silicone resin, and the mass ratio of the sodium silicate and high temperature resistant silicone resin is 1:2;

(3) Dry and sieve the mixed powder obtained in step (2), then add nano silicon dioxide to mix and coat, the mass ratio of the nano silicon dioxide to the initial soft magnetic alloy powder is 0.4%;

(4) Mix the soft magnetic alloy powder coated in step (3) with lubricant, and put it into the mold, then heat it while pressurizing, and press it under warm pressure at a pressure of 1200MPa and a temperature of 60°C Shaping; the mass ratio of the lubricant to the initial soft magnetic alloy powder is 0.4%, the lubricant is a mixture of zinc stearate and polyethylene glycol, and the mass ratio of the zinc stearate and polyethylene glycol The ratio is 5:1;

(5) Perform annealing treatment on the magnetic powder core formed by warm pressing in step (4), the annealing temperature is 750°C, and the annealing time is 1.5h.

Example 7

Performance test of the sendust soft magnetic powder core prepared by the method of the present invention

The properties of the sendust soft magnetic powder cores prepared in Examples 1 to 6 are tested respectively, and the density, magnetic permeability (when 50kHz and 1000kHz), magnetic loss of each group of gained sendust soft magnetic powder cores are tested respectively (50kHz/0.05T), the test results are shown in Table 1.

Table 1 Performance results of sendust soft magnetic powder core

It can be seen from the above results that the sendust soft magnetic powder cores prepared in Examples 1 to 6 above have higher density, higher magnetic permeability and lower magnetic loss, especially those prepared in Example 4. Sensitive soft magnetic powder core has particularly high magnetic permeability and low magnetic loss.

Example 8

In the preparation method of the present invention, the mass ratio of zinc stearate and polyethylene glycol in the lubricant affects the performance of the obtained sendust soft magnetic powder core

There are 9 groups in the test of this embodiment. In the lubricant of each group, the mass ratio of zinc stearate to polyethylene glycol is shown in Table 2.

The mass ratio of zinc stearate and polyethylene glycol of table 2

group Zinc stearate: polyethylene glycol Test group 1 0.02:1

Test group 2 0.1:1 Test group 3 1:5 Test group 4 2:3 Test group 5 1:1 Test group 6 3:2 Test group 7 3:1 Test group 8 4:1 Test group 9 5:1

In this embodiment, test groups 1 to 9 all adopt the method of the present invention to prepare sendust soft magnetic powder cores. In test groups 1 to 9, the mass ratios of zinc stearate and polyethylene glycol in the lubricant are different. Other than that, the other conditions are the same.

The density, permeability (at 50kHz and 1000kHz), and magnetic loss (50kHz/0.05T) of the sendust soft magnetic powder cores prepared by test groups 1 to 9 were tested respectively. The test results are shown in Table 3.

Table 3 Performance test results of sendust soft magnetic powder core

As can be seen from the results in Table 3, in the preparation method of the sendust soft magnetic powder core of the present invention, the mass ratio of zinc stearate and polyethylene glycol in the lubricant to the density and permeability of the obtained soft magnetic powder core rate and magnetic loss have a direct impact. When in the lubricant, the mass ratio of zinc stearate to polyethylene glycol is (3～1):2, the obtained sendust soft magnetic powder core has higher density, higher magnetic permeability and Lower magnetic loss. Especially when in the lubricant, the mass ratio of zinc stearate and polyethylene glycol is 2:3, the gained sendust soft magnetic powder core has higher density, higher magnetic permeability and lower magnetic loss.

Example 9

In the preparation method of the present invention, the test of the influence of the content of the lubricant on the performance of the obtained sendust soft magnetic powder core

There are 7 groups in the test of this embodiment, and in the lubricant of each group, the mass ratio of zinc stearate to polyethylene glycol is 2:3. In this embodiment, test groups 1 to 7 all adopt the method of the present invention to prepare sendust soft magnetic powder cores. In test groups 1 to 7, except that the mass ratio of the lubricant to the initial soft magnetic alloy powder is different, the remaining conditions are the same. The mass ratio of lubricant to initial soft magnetic alloy powder in each group is shown in Table 4.

Table 4 Mass ratio of lubricant to initial soft magnetic alloy powder

group Lubricant: primary soft magnetic alloy powder Test group 1 0.4% Test group 2 0.6% Test group 3 0.8% Test group 4 1% Test group 5 1.3% Test group 6 1.6% Test group 7 2%

The density, permeability (at 50kHz and 1000kHz), and magnetic loss (50kHz/0.05T) of the soft magnetic powder cores prepared by test groups 1 to 7 were tested respectively. The test results are shown in Table 5.

Table 5 Performance test results of soft magnetic powder cores

It can be seen from the results in Table 5 that in the preparation method of the soft magnetic powder core of the present invention, the amount of lubricant also has a direct impact on the density, permeability and magnetic loss of the soft magnetic powder core. When the mass ratio of the lubricant to the initial soft magnetic alloy powder is 0.5-1.5%, the obtained soft magnetic powder core has higher density, magnetic permeability and lower magnetic loss. Especially when the mass ratio of the lubricant to the initial soft magnetic alloy powder is 1.3%, the obtained soft magnetic powder core has higher density, magnetic permeability and lower magnetic loss.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that The technical solution of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. A method for preparing sendust soft magnetic powder core by warm pressing, is characterized in that, comprises the following steps: (1) Utilize passivating agent to carry out passivation treatment to initial soft magnetic alloy powder, dry; (2) uniformly mixing the dried soft magnetic alloy powder and binder in step (1); (3) Dry and sieve the mixed powder obtained in step (2), and then add an insulating agent to mix and coat; (4) Mix the soft magnetic alloy powder coated in step (3) with a lubricant, and put it into a mould, then heat while pressurizing, and press to form under warm pressure; (5) carrying out annealing treatment to the magnetic powder core formed by warm pressing in step (4); The weight percent content of the initial soft magnetic alloy powder is: 8.5-10.5% of silicon, 4.5-6.5% of aluminum, and the balance is iron; The lubricant in the step (4) is a mixture of zinc stearate and polyethylene glycol. 2. warm pressing as claimed in claim 1 prepares the method for sendust soft magnetic powder core, it is characterized in that, in the lubricant of described step (4), the mass ratio of zinc stearate and polyethylene glycol is (0.02～5): 1; Preferably, in the lubricant of described step (4), the mass ratio of zinc stearate and polyethylene glycol is (3～1): 2; More preferably, described step In the lubricant of (4), the mass ratio of zinc stearate and polyethylene glycol is 2:3. 3. the method for preparing sendust soft magnetic powder core by warm pressing as claimed in claim 1 or 2, is characterized in that, in the described step (4), the mass ratio of lubricant and initial soft magnetic alloy powder is 0.4～2 %; Preferably, the mass ratio of the lubricant to the initial soft magnetic alloy powder in the step (4) is 0.5-1.5%. 4. the method for preparing sendust soft magnetic powder core by warm pressing as claimed in claim 1, is characterized in that, the binding agent in the described step (2) is the mixture of sodium silicate, high temperature resistant organic silicon resin; The insulating agent in the step (3) is nano silicon dioxide. 5. the method for preparing sendust soft magnetic powder core by warm pressing as claimed in claim 4, is characterized in that, in the binding agent of described step (2), the mass ratio of sodium silicate and high temperature-resistant silicone resin It is (4-1): 2; preferably, in the binder in the step (2), the mass ratio of sodium silicate and high temperature resistant silicone resin is 3:2. 6. the method for preparing sendust soft magnetic powder core by warm pressing as claimed in claim 1, is characterized in that, the mass ratio of binder in the described step (2) and initial soft magnetic alloy powder is 1～2 %; the mass ratio of the insulating agent to the initial soft magnetic alloy powder in the step (3) is 0-0.4%. 7. the method for preparing sendust soft magnetic powder core by warm pressing as claimed in claim 6, is characterized in that, the mass ratio of binding agent in described step (2) and initial soft magnetic alloy powder is 1.5%; In the step (3), the mass ratio of the insulating agent to the initial soft magnetic alloy powder is 0.1-0.4%. 8. the method for preparing sendust soft magnetic powder core by warm pressing as claimed in claim 1, is characterized in that, the passivating agent that adopts in described step (1) is phosphoric acid solution, and the mass percent of described phosphoric acid solution The concentration is 0.4-3%, and the mass ratio of the phosphoric acid solution to the initial soft magnetic alloy powder is (0.5-1.5):1. 9. The method for preparing sendust soft magnetic powder cores by warm pressing as claimed in claim 1, characterized in that, in the step (4), the pressing pressure of warm pressing and forming is 500-1200 MPa, and the pressing temperature is 60-150 ° C; the annealing temperature of the annealing treatment in the step (5) is 550-750 ° C, and the annealing time is 0.5-1.5 hours. 10. A sendust soft magnetic powder core prepared by the method according to any one of claims 1-9.