KR100499013B1 - Fe-Si alloy powder cores and fabrication process thereof - Google Patents

Abstract

The present invention provides an Fe-Si-based alloy powder core having excellent soft magnetic properties in a high frequency region and a method of manufacturing the same. The Fe-Si-based alloy powder core manufacturing method comprises the steps of dissolving a binder in an organic solvent and water to obtain a binder solution; Preparing a composite particle powder coated with a binder on the Fe-Si-based alloy powder surface by adding and mixing the binder solution to the Fe-Si-based alloy powder; Molding the composite particle powder; And heat-treating the resultant at 400 to 900 ° C. According to the present invention, Fe-Si-based alloy powder cores are prepared by compression molding at room temperature using Fe-Si-based alloy powder and polyimide-based, phenol-based resin and inorganic water-glass as binders. The Fe-Si-based alloy powder core of the present invention has superior frequency characteristics compared to the Fe-Si-based alloy powder core prepared through a high temperature heat treatment process according to the prior art, and is currently commercially available in Sendust and MPP cores. Compared with the soft magnetic characteristics (saturated magnetic flux density, etc.), the frequency characteristics are particularly excellent. Therefore, according to the present invention, the metal powder powder core has excellent molding density, good intergranular insulation, almost no change in permeability even in the high frequency band, and can be used as a magnetic element for electric and electronic devices in the frequency band of several tens of MHz at several kHz. It can be prepared.

Description

          Fe-Si alloy powder core and its manufacturing method {Fe-Si alloy powder cores and fabrication process

       The present invention relates to a Fe-Si-based alloy powder core and a method for manufacturing the same, and more specifically, Fe can be used stably in the high frequency region by using a Fe-Si-based magnetic powder having a low cost and excellent soft magnetic properties Si-based alloy powder core and a method for economically manufacturing the same.

Fe-Si-based alloy powder core is generally pulverized Fe-Si-based alloy into a powder, then molded and heat treated under a predetermined temperature and pressure into a core.

However, since the heat treatment temperature during the manufacturing process is very high, such as 1100 ° C. or more, the Fe-Si-based alloy powder particles are oxidized or sintering occurs during the heat treatment. When the sintering of the Fe-Si-based alloy powder particles occurs as described above, the finally obtained Fe-Si-based alloy powder has a soft magnetic property, but has a high frequency characteristic, which is difficult to apply to more than several hundred kHz band. In addition, since the heat treatment must be made at a high temperature, there is also a problem in that the manufacturing cost increases.

The technical problem to be achieved by the present invention is to solve the above problems to provide a Fe-Si-based alloy powder core having excellent soft magnetic properties in the high frequency region because of the good insulation between powder particles.

Another object of the present invention is to provide a method for economically manufacturing a Fe-Si-based alloy powder core having the above-described characteristics through a low temperature heat treatment process.

In order to achieve the above technical problem, the present invention, (a) dissolving the binder in an organic solvent and water to obtain a binder solution;

(b) preparing a composite particle powder coated with a binder on the Fe-Si-based alloy powder by adding and mixing the binder solution to the Fe-Si-based alloy powder;

(c) molding the composite particle powder; And

(d) heat-treating the resultant at 400 to 900 ° C. to provide a method for producing a Fe-Si-based alloy powder core comprising a.

The Fe-Si-based alloy powder of step (a) preferably comprises 2 to 10 wt% of Si and 90 to 98 wt% of Fe.

The forming step of step (c) is preferably made at a pressure of 10 to 30 ton / ㎠ at room temperature.

The heat treatment step (d) is preferably made in an inert atmosphere or a reducing atmosphere.

The binder used in step (a) uses at least one selected from the group consisting of polyimide resins, phenolic resins and sodium silicates, the content of which is based on the total weight of the solid content of the Fe-Si-based alloy powder cores. It is preferable that it is 0.1-2.0 wt%.

Another technical problem of the present invention is made by the Fe-Si-based alloy powder prepared according to the above-described manufacturing process.

In the present invention, when the Fe-Si alloy powder cores are manufactured, uniformly coating a binder having high binding properties and high strength properties on the surface of the Fe-Si alloy powder having an average particle diameter of several tens of micrometers, and then forming and non-oxidizing at room temperature It is characterized by low temperature heat treatment in an atmosphere.

The Fe-Si-based alloy powder is a crystalline powder, the content of Fe is 2 to 10 wt%, more preferably 4 to 8 wt%. If the content of Fe is less than 2 wt%, the soft magnetic and high frequency characteristics deteriorate. If the content of Fe exceeds 10 wt%, the brittleness of the powder is sharply increased and moldability is largely deteriorated.

The Fe-Si-based alloy powder may be mainly produced by mechanical alloying, quench solidification, water spraying, etc. In the present invention, a powder prepared by a high pressure water spraying method is used.

As for the average particle diameter of the Fe-Si type alloy powder used by this invention, it is more preferable that it is 150 micrometers or less and 10-150 micrometers, and it is especially preferable that it is about 20 micrometers. If the particle diameter of the Fe-Si-based alloy powder exceeds 150㎛, the soft magnetic properties are improved, but the high frequency characteristics are greatly reduced. And the particle size distribution of the Fe-Si-based alloy powder is preferably in the range of 5 to 150㎛.

Hereinafter, a method of manufacturing a Fe-Si-based alloy powder core according to the present invention will be described.

First, the binder is dissolved in an organic solvent and water to prepare a binder solution. Here, if the binder has a softening point lower than the heat treatment temperature of the Fe-Si-based alloy powder, and exhibits a bonding strength at room temperature and maintains the core shape according to the molding pressure at room temperature, it can suppress cracking. Any may be used.

Specific examples of the binder include polyimide resins, phenolic resins, silicates (also called "water glass"), mixtures thereof, and the like. And the content thereof is preferably 0.1 to 2.0 wt% based on the total weight of the solid content of Fe-Si-based alloy powder core. Here, the "solid content gross weight of Fe-Si type alloy powder core" refers to the total weight of the binder which is solid content which comprises Fe-Si type alloy powder core, and Fe-Si type alloy powder.

If the content of the binder is less than 0.1 wt%, the bonding strength is weak, so that the surface cracks frequently occur during the molding of the alloy powder. If the content of the binder exceeds 2.0 wt%, the amount of the binder becomes relatively large, and the bonding strength between the alloy powder particles becomes stronger. However, this is because the amount of the binder in the molded body increases, resulting in a decrease in soft magnetic properties.

The solvent may be used as long as it can dissolve the binder, and examples thereof include methylene chloride, alcohol and water.

The preferred content of the solvent is 50 to 200 ml based on 1 g of binder. If it is less than 50ml, the amount of solution is not enough to uniformly coat the powder, and if it is more than 200ml, it takes a considerable time to dry the solvent after powder coating.

Subsequently, the binder solution obtained according to the above process is added to and mixed with the Fe-Si-based alloy powder to prepare a composite particle powder coated with a binder on the Fe-Si-based alloy powder surface.

Thereafter, the resultant is molded at room temperature under a pressure of 10 to 30 ton / cm 2 to form a core.

If the molding pressure is less than 10 ton / ㎠, the molding density of the core is lowered, the soft magnetic properties are worse, and if the molding pressure exceeds 30 ton / ㎠, the replacement cycle of the mold due to the increase in wear of the molding die and frequent occurrence of surface defects This is because the production costs are higher due to the faster production. And the said molding time is 5 to 30 second, It is preferable to set it as 10 second especially.

The core prepared according to the above process is heat treated. This heat treatment process mainly removes the internal stress caused during the manufacture or molding of the powder and increases the strength of the molded core by curing the binder, or improves the magnetic properties due to the growth of grains during the heat treatment. There is an advantage.

The heat treatment temperature is preferably 400 to 900 ° C, particularly 500 to 800 ° C. If the heat treatment temperature is less than 400 ℃, the internal stress of the molded core is not sufficiently removed, if it exceeds 900 ℃ it is not preferable because the decomposition and manufacturing cost of the binder is high.

The heat treatment step is preferably maintained in a reducing gas atmosphere by using an inert atmosphere or a reducing gas such as hydrogen gas by using an inert gas such as argon gas or nitrogen gas. The heat treatment time is suitably about 10 to 150 minutes. If the heat treatment time is less than 10 minutes, stress relief is not enough, and if it exceeds 150 minutes, productivity is lowered, which is not preferable.

When manufactured according to the above process, the permeability ratio measured in the frequency bands of 10 MHz and 0.1 MHz is 0.85 or more, and the saturation magnetic flux density and the effective permeability compared to powder cores such as MPP (Moly-Permalloy Powder) and Sendust, etc. This excellent Fe-Si alloy powder core can be manufactured.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited only to the following examples.

Example 1

0.5 wt% of polyimide was dissolved in 100 ml of methylene chloride to prepare a prepared polyimide solution.

Subsequently, the polyimide solution was added to and mixed with 95.5 wt% of Fe _93.5 Si _6.5 alloy powder (average particle diameter: 20 μm, particle size distribution: 5 to 150 μm) prepared by water spraying, followed by drying to dry Fe-Si alloy On the surface of the powder was prepared composite particle powder uniformly coated with a polyimide to a thickness of 0.1㎛ or less.

1 g of the composite particle powder was charged into the mold for molding having an outer diameter of 9.65 mm and an inner diameter of 4.78 mm, and then molded at a pressure of about 15 ton / cm 2 at room temperature and under a nitrogen (N ₂ ) or argon (Ar) gas atmosphere. Heat treatment at 740 ° C. for about 60 minutes yielded a Fe—Si alloy powder core.

Average grain size, density and saturated magnetic flux of the Fe-Si-based alloy powder core prepared according to Example 1, effective permeability and permeability ratio in various frequency bands (μ _{10 MHz} / μ _{0.1 MHz} ) is shown in Table 1 below. Here, the average grain size represents the value of the average particle diameter analyzed by XRD (X-ray Diffraction) and Transmission Electron Microscope (TEM), the core density is calculated by dividing the core's actual mass by the volume of the core. The saturation magnetic flux density (B _s ) is measured under an external magnetic field of 5,000 Oe using a Vibrating Sample Magnetometer (VSM), and the effective permeability is measured under an external magnetic field of 10 mOe in each frequency band using an LCR meter. Value. The permeability ratio (μ _{10 MHz} / μ _0.1 MHz) represents the ratio of the permeability values measured at 10 MHz and 0.1 MHz.

Example 2

Except for using Fe _93.5 Si _6.5 alloy powder (average particle diameter: 20㎛, particle size distribution: 5 to 150㎛) instead of Fe _97.0 Si _3.0 alloy powder (average particle diameter: 45㎛, particle size distribution: 5 to 150㎛), Fe-Si-based alloy powder core was prepared in the same manner as in Example 1.

Example 3

A Fe-Si-based alloy powder core was prepared in the same manner as in Example 1 except that the polyimide content was 0.1 wt% and 99.9 wt% Fe _93.5 Si _6.5 alloy powder was used to prepare the polyimide solution.

Example 4

A Fe-Si-based alloy powder core was prepared in the same manner as in Example 1 except that the polyimide content was 1.0 wt% and 99.0 wt% Fe _93.5 Si _6.5 alloy powder was used.

Example 5

A Fe-Si-based alloy powder core was prepared in the same manner as in Example 1 except that water glass (Sodium Silicate) was used instead of polyimide.

Example 6

A Fe-Si-based alloy powder core was prepared in the same manner as in Example 1 except that a phenol-based resin was used instead of the polyimide.

Example 7

A Fe-Si alloy powder core was prepared in the same manner as in Example 1 except that the molding pressure was changed to 10 ton / cm 2.

Example 8

A Fe-Si alloy powder core was prepared in the same manner as in Example 1 except that the molding pressure was changed to 20 ton / cm 2.

Example 9

Except that the heat treatment temperature was changed to 400 ℃, was carried out in the same manner as in Example 1 to prepare a Fe-Si alloy powder core.

Example 10

Except that the heat treatment temperature was changed to 600 ℃, it was carried out in the same manner as in Example 1 to prepare a Fe-Si alloy powder core.

Comparative Example 1

As a comparative example, the characteristics of the powder core of Sendust (Fe _84.1 Si _10.1 Al _5.8 ) having the same size as that of Example 1 commercially available in Korea as a metal alloy powder core commonly used are shown.

Comparative Example 2

The characteristics of MPP (Fe ₁₈ Ni ₈₀ Mo ₂ ) powder cores of the same size as those of Example 1 commercially available in Korea as metal alloy powder cores generally used are shown as comparative examples.

Comparative Example 3

Water glass was used instead of polyimide, and the Fe-Si-based alloy powder core was prepared in the same manner as in Example 1 except that the heat treatment temperature was 1100 ° C.

Referring to Table 1, the Fe-Si-based alloy powder cores prepared according to Examples 1 to 10 exhibited a molding density of 6.0. Accordingly, the saturation magnetic flux density was 1.5T or more and the effective permeability was 100 or more at 100kHz. . Particularly, in the case of Fe-Si alloy powder cores containing 6.5 wt% Si, the powder cores formed at a pressure of 15 Ton / cm ² or more and heat-treated at 740 ° C. have an effective permeability of 130 or more at 100 kHz, and a magnetic permeability ratio (μ _{10 μs} / μ _{0.1 μs} ) also represents 0.85 or more. The MPP and sender powder cores prepared according to Comparative Examples 1 and 2 cannot be applied up to several hundred kHz, whereas the Fe-Si-based alloy powder cores prepared according to Examples 1 to 10 are 10 MHz or more. It can be seen that it is possible to apply until. Moreover, the saturation magnetic flux density also showed the same or more characteristic compared with the case of the comparative examples 1 and 2.

According to the present invention, Fe-Si-based alloy powder cores are prepared by compression molding at room temperature using Fe-Si-based alloy powder, polyimide-based, phenol-based thermosetting resin, and inorganic water-glass as binders. Fe-Si-based alloy powder core of the present invention has excellent frequency characteristics compared to Fe-Si-based alloy powder core prepared through a high-temperature heat treatment process according to the prior art, soft magnetic compared to the present commercially available Sendust and MPP core The characteristics (saturated magnetic flux density, etc.) are excellent, especially the frequency characteristics are excellent. Therefore, according to the present invention, the metal powder powder core with excellent economic efficiency can be used as a magnetic device for electric and electronic devices in the frequency range of several kHz to several tens of MHz, with high molding density and good intergranular insulation. It can be prepared.

Claims (6)

(a) dissolving the binder in an organic solvent and water to obtain a binder solution; (b) adding and mixing the binder solution to the Fe-Si-based alloy powder to prepare a composite particle powder coated with a binder on the Fe-Si-based alloy powder surface; (c) molding the composite particle powder under a pressure of 10 to 30 ton / cm 2 at room temperature ; And (d) heat-treating the resultant at 400 to 900 ° C .; a method for producing a Fe-Si alloy powder core, comprising: a. The method of claim 1, wherein the Fe-Si-based alloy powder comprises Si 2 to 10 wt% and Fe 90 to 98 wt%. delete The method of claim 1, wherein the step (d) is performed in an inert atmosphere or in a reducing atmosphere. The method of claim 1, wherein the binder of step (a) is at least one selected from the group consisting of polyimide resins, phenolic resins, and sodium silicates, Method for producing a Fe-Si-based alloy powder core, characterized in that the content of 0.1 to 2.0 wt% based on the total weight of the solid content of the Fe-Si-based alloy powder core. Fe-Si-based alloy powder core prepared according to the method of any one of claims 1, 2, 4 or 5.