CN102693798A - Preparation method of high-performance nanocrystalline magnetic powder core - Google Patents

Abstract

The invention discloses a preparation method of a high-performance nanocrystalline magnetic powder core, which comprises the following steps: carrying out heat treatment on the iron-based amorphous thin strip prepared by using a rapid cooling method to convert the iron-based amorphous thin strip into a nanocrystalline thin strip; the mass percent of the iron-based amorphous ribbon is as follows: 3-15% of Ni, 1-10% of Si, 1-4% of B, 1-9% of Al and the balance of Fe; crushing the nanocrystalline thin strip to obtain nanocrystalline metal powder; performing ball milling shaping on the nanocrystalline metal powder; screening the nanocrystalline metal powder, and then mixing the nanocrystalline metal powder into powder particle distribution consisting of 90-98% of first powder passing through a sieve of-200 meshes and 2-10% of second powder passing through a sieve of-150 to +200 meshes; mixing the mixed nanocrystalline metal powder with an adhesive, and pressing to form a magnetic core; and annealing the molded magnetic core, and then coating the magnetic core with an insulating resin. The magnetic powder core in the technical scheme has stable magnetic conductivity, loss value and direct current bias capability.

Description

Preparation method of high-performance nanocrystalline magnetic powder core

technical field

The invention relates to a preparation method of a high-performance nanocrystalline magnetic powder core.

Background technique

In power electronic equipment, noise is the main source of circuit interference, so various filter devices must be used to reduce noise. As the main component of the differential mode inductor, the magnetic powder core plays a key role in the filter. At present, the magnetic powder core products mainly include iron powder cores, sendust magnetic powder cores, iron-nickel magnetic powder cores, MPP magnetic powder cores, etc. Conventional iron powder cores are cheap, but have poor high-frequency characteristics. Now when designing and manufacturing various switching power supply choke coils and inductors, sendust magnetic powder cores, iron-nickel magnetic powder cores and MPP magnetic powder cores are basically used.

Compared with iron powder cores, sendust magnetic powder cores have very low core loss, and their frequency characteristics are better, but the DC bias capability of sendust magnetic powder cores at higher currents is poor, so that the iron-silicon The use of aluminum powder cores under adverse conditions is limited.

The iron-nickel magnetic powder core has excellent frequency characteristics in the frequency range of 1MHz, and the loss is low. Moreover, among the metal magnetic powder cores, the iron-nickel magnetic core has the highest DC bias capability, and the product performance is good. However, there is still 50% nickel in the iron-nickel magnetic powder core, which is expensive and the production cost is high.

Similarly, MPP magnetic powder cores also have excellent frequency characteristics in the frequency range of 1MHz, and the core loss is the lowest among various metal magnetic powder cores. However, the DC bias capability of the MPP magnetic powder core is average, and at the same time, the MPP magnetic powder core contains precious metals such as nickel and molybdenum, which are expensive, making it difficult to be widely used.

Contents of the invention

In order to solve the above-mentioned technical problems, the purpose of the present invention is to provide a method for preparing a high-performance nanocrystalline magnetic powder core, which is used to prepare a nanocrystalline magnetic powder core with a magnetic permeability μ=26-90, and the magnetic powder core has a stable magnetic permeability. , loss value and DC bias capability.

In order to achieve the above-mentioned purpose, the present invention has adopted following technical scheme:

A method for preparing a high-performance nanocrystalline magnetic powder core, comprising the steps of:

1) Heat-treat the iron-based amorphous ribbons prepared by the rapid cooling method to transform them into nanocrystalline ribbons; wherein, the mass percentage of the iron-based amorphous ribbons is: 3-15% Ni, 1-10% Si, 1~4%B, 1~9%Al, the balance is Fe;

2) crushing the nanocrystalline thin ribbon to obtain nanocrystalline metal powder;

3) performing ball milling on the nanocrystalline metal powder;

4) Screen the nanocrystalline metal powder, and then mix it into a powder consisting of 90% to 98% of the first powder passing through -200 mesh and 2% to 10% of the second powder passing through -150 to +200 mesh Powder particle distribution;

5) Mixing the mixed nanocrystalline metal powder with an adhesive to form a magnetic core by pressing; and annealing the formed magnetic core, and then coating the magnetic core with an insulating resin.

Preferably, the heat treatment of the iron-based amorphous strip in the step 1) is carried out at 500-700°C in an inert gas for 1-3 hours.

Preferably, the binder in the step 5) is sodium silicate, and the added concentration is 3-8wt‰.

Preferably, the heat treatment of the magnetic core in step 5) is performed at 500-700° C. in a mixed gas of hydrogen and nitrogen for 1-3 hours. Further preferably, the mass ratio of the mixed gas of hydrogen and nitrogen is: 5% to 15% of hydrogen, and the balance is nitrogen.

Due to the adoption of the above technical scheme, the present invention can be used to prepare nanocrystalline magnetic powder cores with a magnetic permeability μ=26-90, and the magnetic powder cores have stable magnetic permeability, loss value and DC bias capability. It has the following advantages: 1. The manufacturing process is simple, the equipment is simple, and the production cost is low; 2. The magnetic core product with specific magnetic permeability produced by the method of the present invention maintains good inductance and high quality factor. , which reduces the loss value of the product and improves the DC bias capability. The nanocrystalline magnetic powder core of the present invention is mainly suitable for power factor correction of switching power supply and output filtering of switching power supply, so as to improve the efficiency of switching power, and can replace sendust magnetic powder core, iron nickel magnetic powder core and MPP magnetic powder core.

Detailed ways

A detailed description will be given below of specific embodiments of the present invention.

A method for preparing a high-performance nanocrystalline magnetic powder core, comprising the steps of:

1) Heat-treat the iron-based amorphous ribbons prepared by the rapid cooling method to transform them into nanocrystalline ribbons; wherein, the mass percentage of the iron-based amorphous ribbons is: 3-15% Ni, 1-10% Si, 1~4%B, 1~9%Al, the balance is Fe;

2) crushing the nanocrystalline thin ribbon to obtain nanocrystalline metal powder;

3) performing ball milling on the nanocrystalline metal powder;

4) Screen the nanocrystalline metal powder, and then mix it into a powder consisting of 90% to 98% of the first powder passing through -200 mesh and 2% to 10% of the second powder passing through -150 to +200 mesh Powder particle distribution;

5) Mixing the mixed nanocrystalline metal powder with an adhesive to form a magnetic core by pressing; and annealing the formed magnetic core, and then coating the magnetic core with an insulating resin.

The invention mainly studies the influence of the preparation process on the performance of the magnetic powder core with the same composition ratio. Next, the eigenvalue of the magnetic permeability is selected as 60, and the solution of the present invention is described through the distribution of powder particles, the heat treatment temperature of the iron-based amorphous strip, the protective gas for the heat treatment of the magnetic powder core, and the proportion of the binder.

Example 1:

The iron-based amorphous thin strips prepared by the rapid cooling method were heat-treated in an inert gas at 580° C. for 1 hour to obtain nanocrystalline thin strips; they were broken and shaped; 90% of the first powder of -200 mesh was selected and 10% of the second powder of -150～+200 mesh, mixed with 5wt‰ sodium silicate, through compression molding, select the magnetic core for annealing, and at the same time pass nitrogen into the heat treatment furnace, the temperature is 500 ° C, the time is 2 hours, and finally The surface of the magnetic powder core is coated with epoxy resin paint. The nanocrystalline magnetic powder core product 1 with the specifications of Φ26.9/Φ14.7×11.2 (that is, the outer diameter is 26.9mm, the inner diameter is 14.7mm, and the height is 11.2mm) is obtained.

Example 2:

Heat-treat the iron-based amorphous thin strips prepared by the rapid cooling method in an inert gas at 620° C. for 1 hour to obtain nanocrystalline thin strips; crush and shape them; select 90% of the first powder of -200 mesh and 10% of the second powder of -150～+200 mesh, mixed with 5wt‰ sodium silicate, through compression molding, select the magnetic core for annealing, and at the same time pass nitrogen into the heat treatment furnace, the temperature is 500 ° C, the time is 2 hours, and finally The surface of the magnetic powder core is coated with epoxy resin paint. The nanocrystalline magnetic powder core product 2 with specifications of Φ26.9/Φ14.7×11.2 (that is, outer diameter 26.9mm, inner diameter 14.7mm, height 11.2mm) was obtained.

Example 3:

The iron-based amorphous thin strips prepared by the rapid cooling method were heat-treated in an inert gas at 620°C for 1 hour to obtain nanocrystalline thin strips; they were crushed and shaped; 95% of the first powder of -200 mesh was selected and 5% of the second powder of -150 ~ +200 mesh, mixed with 5wt‰ sodium silicate, through compression molding, select the magnetic core for annealing, and at the same time pass nitrogen into the heat treatment furnace, the temperature is 500 ° C, the time is 2 hours, and finally The surface of the magnetic powder core is coated with epoxy resin paint. The nanocrystalline magnetic powder core product 3 with specifications of Φ26.9/Φ14.7×11.2 (that is, outer diameter 26.9mm, inner diameter 14.7mm, height 11.2mm) was obtained.

Example 4:

The iron-based amorphous thin strips prepared by the rapid cooling method were heat-treated in an inert gas at 620°C for 1 hour to obtain nanocrystalline thin strips; they were crushed and shaped; 95% of the first powder of -200 mesh was selected and 5% of the second powder of -100 ~ +200 mesh, mixed with 5wt‰ sodium silicate, through compression molding, annealing of the selected magnetic core, and nitrogen gas into the heat treatment furnace at the same time, the temperature is 500 ° C, the time is 2 hours, and finally The surface of the magnetic powder core is coated with epoxy resin paint. Obtained nanocrystalline magnetic powder core product 4 with specifications of Φ26.9/Φ14.7×11.2 (that is, outer diameter 26.9mm, inner diameter 14.7mm, height 11.2mm).

Example 5:

The iron-based amorphous thin strips prepared by the rapid cooling method were heat-treated in an inert gas at 620°C for 1 hour to obtain nanocrystalline thin strips; they were crushed and shaped; 95% of the first powder of -200 mesh was selected and 5% of the second powder of -150 ~ +200 mesh, mixed with 5wt‰ sodium silicate, through compression molding, select the magnetic core to anneal, and at the same time pass hydrogen into the heat treatment furnace, the temperature is 500 ° C, the time is 2 hours, and finally The surface of the magnetic powder core is coated with epoxy resin paint. The nanocrystalline magnetic powder core product 5 with specifications of Φ26.9/Φ14.7×11.2 (that is, outer diameter 26.9mm, inner diameter 14.7mm, height 11.2mm) was obtained.

Example 6:

The iron-based amorphous thin strips prepared by the rapid cooling method were heat-treated in an inert gas at 620°C for 1 hour to obtain nanocrystalline thin strips; they were crushed and shaped; 95% of the first powder of -200 mesh was selected and 5% of the second powder of -150 ~ +200 mesh, mixed with 5wt‰ sodium silicate, through compression molding, select the magnetic core for annealing, and at the same time pass the mixed gas of hydrogen and nitrogen into the heat treatment furnace (hydrogen 5 ~ 15wt %), the temperature is 500°C, the time is 2 hours, and finally the surface of the magnetic powder core is coated with epoxy resin paint. The nanocrystalline magnetic powder core product 6 with specifications of Φ26.9/Φ14.7×11.2 (that is, outer diameter 26.9mm, inner diameter 14.7mm, height 11.2mm) was obtained.

The above example products are tested and explained as follows:

(1) f﹑L﹑Q test

The copper wire is Φ0.5mm, and the number of turns of the coil is 26 turns. The magnetic performance parameters of the above products 1 to 6 are listed in Table 1:

(2) Power loss test

The copper wire is Φ0.8mm, and the number of turns of the coil is 34 turns. The magnetic performance parameters tested by the above products 1 to 6 are shown in Table 2:

product Frequency f(kHz) Magnetic flux density B _pk (Gauss) Power loss (mW/cm3) Product 1 50 1000 292 Product 2 50 1000 278 Product 3 50 1000 271 Product 4 50 1000 305 Product 5 50 1000 283 Product 6 50 1000 259

(3) Magnetic performance test

The copper wire is Φ0.8mm, the number of coil turns is 34 turns, and the frequency is 100kHz. The magnetic performance parameters tested by the above products 1 to 6 are shown in Table 3:

(4) Saturation magnetic induction

The primary copper wire is Φ0.5mm, the number of coil turns is 200 turns, the secondary is Φ0.29mm, and the number of coil turns is 50 turns. The magnetic performance parameters of the above products 1 to 6 tested by the B-H loop test instrument are as follows:

product Saturation magnetic induction (Gauss) Product 1 11000 Product 2 12000 Product 3 12000 Product 4 11500 Product 5 12500 Product 6 13000

On the effect of metal powder particle distribution on magnetic core performance. From the comparison of the data of product 3 and product 4, it can be seen that compared with product 3, as the powder particles increase (the second powder of product 3 is -150 ~ +200 mesh, the second powder of product 4 is -100 ~ +200 mesh mesh), the quality factor Q of product 4 is significantly reduced, the power loss is significantly increased, and the DC bias capability is significantly reduced. And, through more experiments of the inventor, it is proved that "the particle distribution of the powder composed of 90% to 98% of the first powder passing through -200 mesh and 2% to 10% of the second powder passing through -150 to +200 mesh "It is the best choice for preparing nanocrystalline magnetic powder cores with a magnetic permeability of μ = 26-90. It has a relatively stable magnetic permeability and has a small loss value and good DC bias capability. When the first powder passing -200 mesh exceeds 98%, the air gap of the magnetic core will be too small, and the DC bias capability will be significantly reduced; when the first powder passing -200 mesh is less than 90%, the air gap of the magnetic core will be too large, Power loss increases significantly.

On the effect of heat treatment temperature of iron-based amorphous ribbon on the performance of magnetic core. From the comparison of the data of product 1 and product 2, it can be seen that the performance data of the two products are slightly different, but they all meet the design requirements. In addition, more experiments by the inventors have proved that when the heat treatment temperature is below 500°C or above 700°C, the magnetic permeability significantly deviates from the design characteristic value (more than 5%). Therefore, "iron-based amorphous strip heat treatment at 500 ~700°C, in an inert gas for 1~3 hours" is the best choice for preparing nanocrystalline magnetic powder cores with a magnetic permeability μ = 26 ~ 90, which has a relatively stable magnetic permeability and a small loss value and better DC bias capability.

About the effect of heat treatment shielding gas on the performance of magnetic powder core. From the data comparison of product 3, product 5 and product 6, it can be seen that product 3 (nitrogen protection) and product 6 (nitrogen, hydrogen combination) have better performance than product 5 (hydrogen protection), and further, product 6 ( Compared with product 3 (nitrogen protection), the combination of nitrogen and hydrogen has a slight improvement in the stability of magnetic permeability, loss value and saturation magnetic induction.

For the addition ratio of the adhesive, see the following examples:

Example 7:

The iron-based amorphous thin strips prepared by the rapid cooling method were heat-treated in an inert gas at 580° C. for 1 hour to obtain nanocrystalline thin strips; they were broken and shaped; 90% of the first powder of -200 mesh was selected and 10% of the second powder of -150～+200 mesh, choose sodium silicate as the binder, add and mix according to 1wt‰, 3wt‰, 5wt‰, 8wt‰, 10wt‰ respectively, press molding, select the magnetic core Annealing, while feeding a mixed gas of hydrogen and nitrogen (hydrogen 5-15wt%) into the heat treatment furnace at a temperature of 500°C for 2 hours, and finally coating the surface of the magnetic powder core with epoxy resin paint. Product 7, Product 8, Product 9, Product 10, and Product 11 of nanocrystalline magnetic powder cores with specifications of Φ26.9/Φ14.7×11.2 (that is, outer diameter 26.9mm, inner diameter 14.7mm, height 11.2mm) were obtained.

The above-mentioned product 7, product 8, product 9, product 10, and product 11 were tested under the same conditions, and the comparative data in terms of magnetic permeability, magnetic core loss (50kHz/1000Gs), and DC bias (100Oe) are shown in the table below Show:

It can be seen from the table that the amount of binder added has a great influence on the performance of the product. When the amount of binder added is too high (over 8wt‰), the magnetic permeability of the magnetic powder core will decrease, and the core loss will increase. The DC bias capability will be reduced; when the amount of adhesive added is too small (less than 3wt‰), the performance of the product will deteriorate, and even the product cannot be molded. Therefore, "the binder is sodium silicate, and the added concentration is 3-8wt‰" is the best choice for preparing nanocrystalline magnetic powder cores with a magnetic permeability μ = 26-90. Small loss value and better DC bias capability, and further, the addition concentration of sodium silicate is 5wt‰ is the optimal choice.

Although the above-mentioned examples all have a magnetic permeability of 60 eigenvalues, according to more experiments by the inventor, the above-mentioned preparation method is also applicable to nanocrystalline magnetic powder cores with a magnetic permeability μ=26-90, which can be used in a Stable magnetic permeability has small loss value and good DC bias ability at the same time, so as to ensure the consistency of production products and design requirements.

The soft magnetic performance results of various magnetic powder cores with a magnetic permeability of 60 are given in the following table, which shows that the present invention has excellent soft magnetic performance.

It should be emphasized that: the above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention are valid. Still belong to the protection scope of the present invention.

Claims (5)

1. the preparation method of a high performance nano-crystal magnetic core comprises the steps:

1) iron-based amorphous thin ribbon that utilizes method for rapid cooling to make is heat-treated, be converted into nano-crystalline thin ribbon; Wherein, the iron-based amorphous thin ribbon mass percent is: 3～15%Ni, and 1～10%Si, 1～4%B, 1～9%Al, surplus is Fe;

2) said nano-crystalline thin ribbon is carried out fragmentation and obtain the nanocrystalline metal powder;

3) said nanocrystalline metal powder is carried out the ball milling shaping;

4) said nanocrystalline metal powder is screened, the powder particle that is mixed into then by second powder constituent that passes through-150～+ 200 sieve meshes of 90%～98% first powder that passes through-200 sieve meshes and 2%～10% distributes;

5) the nanocrystalline metal powder that mixes is mixed with bonding agent again, through the compression moulding magnetic core; And the magnetic core of said moulding annealed, be coated with said magnetic core with insulating resin then.

2. a kind of method for preparing high performance nano-crystal magnetic core according to claim 1 is characterized in that the iron-based amorphous thin ribbon heat treatment in the said step 1) was carried out 1～3 hour under 500～700 ℃, in inert gas.

3. a kind of method for preparing high performance nano-crystal magnetic core according to claim 1 is characterized in that the bonding agent in the said step 5) is a sodium metasilicate, and adding concentration is 3～8wt ‰.

4. a kind of method for preparing high performance nano-crystal magnetic core according to claim 1 is characterized in that, the magnetic core heat treatment in the said step 5) was being carried out 1～3 hour under 500～700 ℃, in the mist of hydrogen and nitrogen.

5. a kind of method for preparing high performance nano-crystal magnetic core according to claim 4 is characterized in that, the mist mass ratio of said hydrogen and nitrogen is: hydrogen 5～15%, surplus are nitrogen.