KR100314839B1 - Method for producing dust core containing dust from iron mill - Google Patents

Abstract

PURPOSE: Provided is a method for producing dust core containing dust from an iron mill by adding dust from an iron to pure steel dust, whereby the produced dust core has magnetic properties equal to or better than those of pure steel dust. CONSTITUTION: The method for producing dust core containing dust from an iron mil l includes the steps of providing dust from an iron mill with a particle size of 250 micrometer, which contains 12 % by weight of iron(Fe), based on the weight of metal components except for oxygen, and is present in a form of oxides; mixing the dust with iron powder with a particle size of 44 to 150 micrometer; adding 1 to 2 % by weight of a silane-based coupling agent to the mixture powder, followed by surface treating with a solvent; adding 0.25 to 2 % by weight of a binder mixed with a curing agent to the surface treated powder, followed by mixing; and forming the mixture powder under a pressure of 8 to 10 torr/cm¬3, followed by curing at a temperature of 100 to 200 deg.C. for 1 to 2 hours.

Description

Manufacturing method of pressed powder core containing dust in steel mill

The present invention relates to a method for producing a powdered core, and more particularly, to manufacturing a powdered powder by adding iron dust to iron powder to produce a powdered powder. It relates to a manufacturing method.

Recently, the demand for switching mode power supply is gradually increasing from the viewpoint of energy saving due to light and short and small size of electronic and electrical equipment, and about 90% of power is being replaced by switching power. . Switching power supplies are used in a wide range of applications, from business equipment such as large computers and office equipment to home appliances such as TV and video.

At present, the biggest problem in switch power supply is miniaturization technology. To this end, technology development is being progressed toward high frequency switching, miniaturization of parts, reduction of parts, simplification of circuits, and promotion of high density mounting. The most influential effect on the miniaturization of such a switch power supply is a magnetic component of the main components, which is excellent in high frequency characteristics and requires development of low loss and low noise core materials.

The main magnetic properties required for such magnetic parts are slightly different in priority depending on the function of the parts, but in general, high magnetic permeability, high angle formation, high saturation magnetic flux density, and low iron loss are required.

For example, a normal mode choke filter of the magnetic parts, the choke filter is required to use a core having a high saturation magnetic flux density because the load current is overlapped. Currently, soft ferrite, which is spotlighted by high magnetic permeability and low iron loss due to the high specific resistance of the material, cannot be used in the choke filter because the magnetization value is about 1/10 of that of the metal material. .

In general, a powder core, a silicon steel core, and an amorphous core are used as cores for a normal mode choke filter. In the case of the silicon steel core, the orientation needs to be considered, and the increase in manufacturing cost due to material processing is pointed out as a problem, and in the case of the amorphous magnetic core, poor temperature stability, workability due to brittleness, and increase in manufacturing cost due to brittleness This raises questions about productivity.

However, in the case of iron-based green powder core has been used for a long time by mixing the binder and molding, there is an advantage that can be produced in a material of the same shape or complicated shape as the final product at a low cost. In particular, the iron-based green powder core has a high temperature stability and high magnetic properties at high frequency induction with high Curie temperature of iron, and shows excellent attenuation characteristics when pulsed noise is input.

Accordingly, interest in high-performance, high-efficiency iron-based powder cores has been attracting new attention, and efforts are being made to develop (Digest of Soft Magentic Materials '96: Gorham / Intertech Consulting, San Francisco, U.S.A.) in Europe.

Conventionally, as a magnetic component to be used at high frequency, the core of manufacturing a powder core is to add an alloy having a high resistivity metal or semimetal to iron powder to reduce eddy current loss, to prepare an alloy powder, melt it, and then rapidly cool to make powder. By producing an insulating coating of the surface of the powder with a resin, magnetic properties of high saturation and high permeability at high frequencies are obtained. However, the method has a problem in that the manufacturing process is complicated by the addition of a molten and rapid cooling process to produce an alloy powder in order to reduce the eddy current loss.

On the other hand, in integrated steelworks equipped with steel making and steel making facilities, a large amount of dust having different physical and chemical properties is generated depending on the generation process. For example, the total amount of various dusts generated by Pohang Iron & Steel Co., Ltd. is estimated to be about 700,000 tons per year. It is becoming. In terms of generation, 36.3 million tonnes in the blast furnace, 8.10,000 tonnes in the sintering section, 1.90,000 tonnes in the small-fired section, 184,000 tonnes in the steelmaking section, 1.30,000 tonnes in the STS section, and 380,000 tonnes in the coke section. As such, the huge amount of dust shows different characteristics according to the characteristics of the generation sector. Currently, Pohang Iron & Steel Co., Ltd. sells 21.2 million tons of dust, 42.1 million tons, and 6.6 million tons of landfill, which makes up 90.5% of dust. Doing. Among them, the metal, which is the main component, is collected and handed over to a partner company to dissolve, and separated into metal ingots and slag.Ingots are purchased again from Pohang Iron & Steel Co., Ltd. and used as raw materials, and slag is disposed of by landfilling. This method is inefficient because it requires additional equipment and costs for disposal. In addition, since there is a waste of heavy metal components harmful to the human body in any form in this process, there are also problems in terms of environmental protection.

Therefore, the present inventors obtain the effect of suppressing the eddy current loss at the high frequency and at the same time advantageously by adding the steel mill dust to be discarded in place of the element or semimetal having a high resistivity in manufacturing the powder core as a magnetic part to be used at high frequency. It has come to propose a new method for producing a powdered core.

That is, the object of the present invention is to control the production method by adding the steel-generating dust to the pure iron in the appropriate amount and the appropriate particle size, and compared with the pure iron powder core, the magnetic permeability is higher than the equivalent level at high frequency, and the magnetic powder has good frequency dependency It is to provide a method of manufacturing.

1 is a graph showing a change in magnetic properties and green compact density according to a binder amount and a dust addition amount in a stainless steel dust-dust-compacted powder core manufactured by the method of the present invention.

Figure 2 is a graph showing the change in magnetic properties according to the frequency and the amount of dust added in the stainless steel dust-processed powdered powder core manufactured by the method of the present invention

The present invention is a method for producing a powder core,

Classifying the steel mill dust containing 12 wt% or more of iron (Fe) in the form of a weight ratio of only metal components excluding oxygen to an particle size of 250 μm or less;

Mixing the sorted dust and pure iron (Fe) powder having a particle size of 44-150 μm;

Adding 1-2 wt% of a silane coupling agent to the mixed powder and dissolving it in a solvent to perform a surface treatment;

Adding 0.25-2% by weight of a binder mixed with a resin and a curing agent to the surface-treated powder and then mixing; and

Molding the mixed powder at a pressure of 8-10 ton / cm 2 and then curing the mixture powder for 1-2 hours at a temperature of 100-200 ° C .;

It relates to a method for producing a steel mill dust-containing pressure powder core comprising a.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

First, steel mill dust suitable for the present invention may be iron mill dust containing 12% by weight or more of iron (Fe) in terms of weight ratio of only metal components excluding oxygen, and present in an oxide form. The reason is that if the density of oxide-type dust added to increase the specific resistance of pure iron powder to suppress eddy current loss is too small, that is, if the iron content is less than 12% by weight, the dust having much lower density than that of pure iron contains a large amount of core. This is because the magnetic properties are deteriorated such that the density of the green compact is significantly reduced due to the increase in volume. In order to suppress this as much as possible, it is preferable that the weight of the dust contains 12 wt% or more of iron (Fe) when converting only the metal component excluding oxygen.

It is possible to maintain the magnetic properties of the green compact, which is an iron-based dust in the form of an oxide that satisfies the iron content.

Representative kinds of steel mill dust suitable for the present invention are Fe: 40-45% by weight, Cr: 13-17% by weight, Ca: 9-12% by weight in terms of weight ratio of only metal components excluding oxygen. And dust generated in the stainless steel making process including Cl, Zn, Mn, Cu, Si, Ni, and K.

As another representative type of iron dust suitable for the present invention, Mg: 25-30% by weight and Ca: 22-26% by weight in terms of weight ratio of only metal components excluding oxygen. Fe: 12-26% by weight is the main component, and dust generated in the ladle furnace (Ladle Furnace) consisting of the remaining Mn, K, Si, Al, P, S, and Ti.

These dusts are formed by the vaporized metal reacted with oxygen in the furnace in the steelmaking process, and is usually collected by a dust collector. The size of the particle is a fine powder having an average particle diameter of 1 μm or less, although in some cases, it is very small. More than 1000 micrometers is also found. It is preferable to remove such dust before molding using a sieve of 250 μm or less. This is because, when a large particle size is added, the density of the green compact is reduced, and thus the magnetic flux density in the magnetic properties of the powder core is small. Because there is.

The classified dust as described above is mixed with the pure iron (Fe) powder, the addition amount of the dust generated in the stainless steel process is added to 3-7% by weight relative to the pure iron powder amount, and generated as a ladle during the steelmaking process Dust is preferably added at 3-5% by weight. The reason is that when it is added below 3% by weight, relatively good magnetic properties are obtained compared to pure iron powder core, but the amount of dust available in terms of recycling of dust is not significant. When more than 7% by weight or 5% by weight of dust is added, it means that dust containing much lower density than core iron is contained in the form of complex oxide, which means that the magnetic permeability decreases significantly due to the increase in volume, resulting in high permeability. Because you can not expect.

At this time, the pure iron powder has a particle size of 44-150 μm. The reason is that the magnetic flux density value of 44 μm or less is high among the magnetic properties after the production of the powdered core, but the contamination on the surface and the small path grain size due to the increase of the surface area of powder The grain boundary increased due to the negative influence on soft magnetic properties such as coercive force and permeability, and more than 150㎛ because high molding density cannot be obtained due to the reduction of contact area between powders and high magnetic flux density. At this time, more preferably in the range of 74-150㎛ for the best magnetic properties.

The mixed powder mixed as above is surface treated using a coupling agent (coupling agent). In this case, the coupling agent used may be a silane, but more preferably r-aminopropyl triethoxy silane, r-glycidoxypropyl trimethoxy silane (gamma-glycidoxypropy1 trimethoxy). silane), and r-methacryloxypropyl trimethoxysilane (gamma-methacryloxypropy1 trimethoxy silane). The addition amount is preferably 0.5-2.0% by weight with respect to the pure iron powder, because the effect of the coupling agent is insufficient at 0.5% by weight or less, and the unreacted coupling agent remains at 2.0% by weight or more to reduce the magnetic flux density. Because.

In the present invention, the surface treatment of the mixed powder is preferable because it is uniformly coated on the surface of the mixed powder to mix using a solvent such as acetone.

It is preferable to add and mix in the range of 0.25-2 weight% the binder which resin and the hardening | curing agent were mixed with the powder surface-treated with the coupling agent as mentioned above. The reason for this is that when the binder is added in an amount of 0.25 wt% or less, the mechanical strength is lowered, and when the binder is added in an amount of 2 wt% or more, the magnetic flux density is decreased. 0.5 weight% binder may be added. At this time, it is preferable that the binder is a mixture of a resin and a curing agent in a ratio of 10: 9.

In order to increase the magnetic flux density of the mixed powder as described above, the molded body density may be increased. In this case, the molding pressure is preferably in the range of 8-10 ton / cm 2 and molded into a mold coated with a lubricant.

The reason for this is that high molding density cannot be obtained below 8ton / cm2, and mold breakage is feared above 10ton / cm2, and the stress inside the powder may adversely affect the magnetic properties due to the strong friction between the mold and the powder. This is because the pressure is more preferably 10 ton / cm 2.

The molded article molded as described above is put into a vacuum dry oven to be cured by heating 1-2 hours at a temperature range of 100-200 ℃ to produce a powder core.

As such, when the mixed powder mixed with pure iron powder and steel mill dust is formed in accordance with the conditions set forth in the present invention, a high permeability can be exhibited, and magnetic powder can be produced with a pressed powder core having good frequency dependence.

Hereinafter, the present invention will be described in detail through examples.

Example 1

Particulates in the form of composite oxides contain only 40% by weight of Fe, 40-45% by weight, Cr: 13-17% by weight, and Ca: 9-12% by weight. Dust generated in the stainless steel making process including, Mu, Cu, Si, Ni, and K is classified to a particle size of 250 μm or less, and 3-10 wt% of 74-150 μm pure iron (Fe) powder After the basis weight was mixed with pure iron powder.

1.0 wt% of a coupling agent of gamma-aminopropyl triethoxy silane was added to the mixed powder mixed as described above, and then dissolved in acetone to surface-treat the mixed powder and then the resin (YD-128, diglycil ether of bisphenol A (Kukdo Chemical) and a curing agent (MNA, methyl-5-norbornene, 3-dicaboxlic anhydride, Kukdo Chemical) were added to the surface treated powder by adding 0.25% by weight of a binder. Mixed. The powder after the pre-molding process was charged into a mold having zinc stearate coated with a lubricant as an inner diameter and an outer diameter of φ10 mm and φ 15 mm, respectively, and then a molded article having a thickness of about 2 mm was produced at a pressure of 10 ton / cm 2 under normal pressure. Thereafter, the molded body was cured in a vacuum oven at 150 ° C. for 1 hour.

) 및 손실(P)은 자숙밀도(B)가 0.05테슬러(T)이고 주파수가 25kHz일 때 얻어진 값이다.The effect of the amount of binder on the magnetic properties and density of the compacted powder core prepared by the above method was investigated for the amount of dust added, and the results are shown in FIG. 1 in comparison with the magnetic characteristics of the pure iron powder core. In Figure 1 the coercive force (Hc), amplitude specific permeability (

) And loss (P) are values obtained when the ripening density (B) is 0.05 Tesla (T) and the frequency is 25 kHz.

) 및 철손실(P)의 특성은 바인더 첨가량이 0.25중량%에서 2중량%로, 분진의 첨가량이 10중량%로 증가함에 따라 더욱 열악해지는 경향이 나타났으며, 특히 10중량%이상 분진과 1중량%이상 바인더의 첨가시는 상기의 측정조건으로는 측정 불가능할 정도의 열악한 자기특성을 나타내었다.As shown in FIG. 1, the density decreases as the amount of binder added increases. On the other hand, the coercive force (Hc) and the total permeability (

) And the iron loss (P) showed a tendency to worsen as the amount of binder added from 0.25% by weight to 2% by weight, the amount of dust added to 10% by weight, in particular, dust and 1 more than 10% by weight The addition of a binder by weight or more showed poor magnetic properties that could not be measured under the above measurement conditions.

)은 129에서 114로 12%정도 감소하는 매우 양호한 특성을 나타냈다. 한편, 이와같은 자기특성은 바인더의 량이 0.25중량%에서 2중량%증가할 때 순철 압분코아와 비교하면 보자력(Hc)은 17% 정도인 0.67 0e에서 0.790e로 증가하고, 진폭비투자율(

)은 129에서 95로 27%정도 감소하므로 압분코아의 자기특성에 미치는 분진의 첨가량은 바인더의 첨가량 영향보다도 상대적으로 훨씬 작아 압분코아의 제작에 있어서 바인더량의 최적화가 매우 중요하다고 판단되었다.However, when 0.25 wt% binder is added and 5 wt% dust is added to the pure iron powder, the coercive force (Hc) increases from 0.67 0e, which is about 16%, to 0.780e compared to pure iron powder core, and the amplitude permeability (

) Shows a very good characteristic of 12% decrease from 129 to 114. On the other hand, when the amount of binder increased from 0.25% by weight to 2% by weight, the coercive force (Hc) increased from 0.67 0e, which is about 17%, to 0.790e when compared to the pure iron pressed core, and the amplitude specific permeability (

) Decreases by 27% from 129 to 95, so the amount of dust added to the magnetic properties of the powder core is much smaller than that of the binder.

) 및 손실(P)은, 자속밀도(B)가 0.05테슬러(T)일때 얻어진 값이다.In FIG. 2, the effect of frequency on the magnetic properties of the powdered core was investigated for the amount of dust added, and the results are compared with those of the pure iron powdered core. The coercive force (Hc) and amplitude specific permeability (

) And the loss P are values obtained when the magnetic flux density B is 0.05 Tesla T.

)는 129에서119로 7.8% 감소하는 반면 10중량% 분진 첨가시 보자력(Hc)은 0.930e에서 1.590e로 약 70%증가하고, 진폭비투자율(

)은 91에서 85로 6.5%감소하는 정도였다.In Fig. 2, the magnetic properties of the entire compressed powder become poor with increasing frequency, but when the frequency is increased from 25 kHz to 200 kHz, the coercive force (Hc) of pure iron core is about 90% from 0.670e to 1.280e. Increased amplitude,

) Decreases by 7.8% from 129 to 119, while the coercive force (Hc) increases by about 70% from 0.930e to 1.590e when 10% by weight of dust is added.

) Decreased 6.5% from 91 to 85.

Table 1 below shows the magnetic properties by comparing the powdered core and the pure iron powdered core when adding dust exhibiting good magnetic properties in the present invention.

As shown in Table 1, Inventive Example (1-3) and Conventional Example (1-3) are not obtained from the exact same process variables, so it is difficult to accurately compare them quantitatively, but Inventive Example (1-3). The permeability at 50 KHz is somewhat poor compared to the conventional example (1-2), while the permeability at a high frequency of 200 KHz is comparable to that of the conventional example (3) and is much better than the conventional example (1-2). The value was shown.

The reason for this characteristic is that it was mixed with the added binder to simply increase the volume of the core.

Example 2

Composite oxide type dust is composed of Mg: 25-30% by weight, Ca: 22-26% by weight and Fe: 12-26% by weight in terms of weight ratio of only metal components excluding oxygen, and the remaining Mn, K, Si The dust generated in the steelmaking process ladle process including, Al, P, S, and Ti was classified in the same manner as in Example 1, mixed with pure iron powder in a certain weight ratio, to prepare a pressed powder core, and then Evaluated.

Since the change in magnetic properties qualitatively coincides with the change in FIG. 1, the result can be considered with the same contents.

Table 2 below shows the magnetic properties of the powdered core with added dust exhibiting good magnetic properties in the present invention as in Example 1 compared with the conventional example (1-3).

As shown in Table 2, in the case of the present invention (4-5), the magnetic permeability at 50 KHz is rather poor compared to the conventional example (1-2), while the permeability at the high frequency of 200 KHz is the same as that of the conventional example (3). It was similar and was showing significantly better values than the conventional example (1-2).

As described above, according to the present invention, by adding the appropriate amount of iron dust at an appropriate granularity and controlling the production method, the steel sheet dust-containing pressed powder core having a magnetic property equivalent to or higher than that of pure iron powder core is increased by increasing the specific resistance of the green compact. It has the effect of providing a way.

In addition, the present invention has a useful effect that can be added to the core of the parts are required to be added to the high-value steel mill dust to be discarded or require additional equipment for reproduction.

Claims (10)

In the method for producing a powder core, Classifying the steel mill dust containing 12 wt% or more of iron (Fe) in the form of a weight ratio of only metal components excluding oxygen to an particle size of 250 μm or less; Mixing the classified dust and iron (Fe) powder having a particle size of 44-150 μm: Adding 1-2 wt% of a silane coupling agent to the mixed powder and dissolving it with a solvent to perform surface treatment; Adding 0.25-2% by weight of a binder mixed with a resin and a curing agent to the surface-treated powder and then mixing; and Molding the mixed powder at a pressure of 8-10 ton / cm 2 and then curing the mixture powder for 1-2 hours at a temperature of 100-200 ° C .; Method for producing a dust-containing pressed powder core ironworks, characterized in that comprising a. The method of claim 1, wherein the steel mill dust is a dust produced in the stainless steel manufacturing process, steel mill dust-containing dust powder core manufacturing method. The method of claim 2, wherein the dust generated in the stainless steel manufacturing process is based on the weight ratio of only metal components excluding oxygen: Fe: 40-45% by weight, Cr: 13-17% by weight, Ca: 9-12% by weight Is a main component, and the remaining Cl, Zn, Nn, Cu, Si, Ni, K, characterized in that it comprises a steel mill dust-containing powdered powder core manufacturing method. The method for producing a mill-containing dust powder core according to claim 2 or 3, wherein the dust generated in the stainless steel process is added at 3-7% by weight. The method of claim 1, wherein the steel mill dust is dust produced in the ladle process during the steelmaking process. The dust generated in the ladle process during the steelmaking process is Mg: 25-30% by weight, Ca: 22-26% by weight, Fe: 12-26 Weight% is the main component, the method of producing a steel mill dust-containing pressure-powder core comprising the remaining Mn, K, Si, Al, P, S, and Ti. The method of claim 5 or 6, wherein the dust generated in the ladle process during the steelmaking step is added by 3-5% by weight. The method of claim 1, wherein the silane coupling agent is selected from the group consisting of r-aminopropyltriethoxysilane, r-glyoxyoxypropyl trimethoxysilane, and r-methacrylic propyl trimethoxysilane. A method for producing a dust mill-containing pressed powder core, characterized in that one species. The method of claim 1, wherein the resin and the curing agent are mixed at a ratio of 10: 9. 2. The method of claim 1, wherein the solvent is acetone.

Images