WO2014021524A1

WO2014021524A1 - Alloy powder, alloy powder core, and method for producing same

Info

Publication number: WO2014021524A1
Application number: PCT/KR2012/011764
Authority: WO
Inventors: 장평우; 신승찬
Original assignee: 청주대학교 산학합력단
Priority date: 2012-07-31
Filing date: 2012-12-28
Publication date: 2014-02-06
Also published as: KR101441745B1; KR20140016674A

Abstract

The present invention provides a soft magnetic powder, a method for producing same, and a soft magnetic powder core produced by the method. According to the present invention, an alloy powder is heat-treated in the presence of a gas in which hydrogen and moisture are mixed together, and in which solute elements are selectively oxidized, so as to form a high-quality insulation layer in a completely different manner from the alloy powder cores of the prior art.

Description

Alloy Powder, Alloy Powder Core and Manufacturing Method Thereof

The present invention relates to an alloy powder and a core, and in particular, a Fe-Al alloy powder is heat-treated on a mixed gas of hydrogen and steam to prepare a metal alloy powder having a high quality insulating layer formed by selectively oxidizing Al, a solute element, and using the same. The present invention relates to a soft magnetic powder, a method for producing the powder, and an alloy powder core produced by the method by producing a soft magnetic core in a completely different method from the existing alloy powder core.

The present invention is the result of a research carried out supported by the Ministry of Education, Science and Technology in 2012 (research project name: general researcher support, research project name: forming a high-quality insulating film for soft magnetic metal powder).

As the world's population grows and technology develops rapidly, production and economy grow greatly according to the parts and automation of machines, making human life rich and convenient.

On the other hand, environmental problems such as resource depletion, air pollution, noise, dust, industrial waste, and waste, global warming, ozone layer destruction, and acid rain caused by increased fossil fuel consumption have resulted in a great global problem. There is a situation. As a result, countries around the world are tightening regulations.

Developed countries are trying to solve global environmental problems by finding new sources of energy in the field of new and renewable energy and at the same time increasing the efficiency of existing energy converters. Representative energy converters include electromechanical devices such as motors and generators that convert electrical energy into mechanical energy, and inductors, which are cores for power conversion.

The devices that convert electrical energy into mechanical energy and vice versa are motors and generators, respectively. The inductor is a soft magnetic core wound around a conductor, which is an essential core element in most electronic devices. Cores used in motors, generators, and inductors are made of soft magnetic materials. The cores used here are responsible for accumulating and returning magnetic energy from the electromagnetic point of view and inevitably causing energy losses. Accordingly, the core material of the inductor generally requires high permeability, high resistivity, small coercive force, high Curie temperature and high saturation magnetic flux density in order to have low loss and high conversion efficiency characteristics. In particular, as electronic devices such as smartphones and tablet PCs are required to have high speed, miniaturization, and high capacity, frequency and high current stability of the high frequency band (1 MHz or more) permeability, which is essential for the directization of components, are also required.

Soft magnetic materials are classified into two types of ferrite-based and metal alloy-based materials. Since ferrite has a specific resistance of 10 ² ~ 10 ¹⁰ Ω · cm, which is about 10 ⁶ times higher than that of metal magnetic materials, it has very little eddy current loss and can be manufactured by powder sintering method. It is possible to manufacture, and because it is an oxide has the advantage of excellent corrosion resistance. However, because it is an oxide, its initial permeability is 1/10 and its magnetic flux density is about 1/3, which is inadequate for low-frequency, high-power magnetic materials, and its Curie temperature is also lower than that of metal magnetics. Have

In comparison, metal alloys generally have high direct current permeability and low magnetic history loss, and are excellent in workability and stability. However, due to the relatively low resistivity, the eddy current loss increases with increasing frequency, thereby limiting its use in the high frequency region.

In order to overcome the limitations of the metal alloy system, the bulk material is powdered to form an insulating layer on each surface of the powder, and compressed and molded into a core to effectively block the eddy current flow as shown in FIG. It can be lowered to improve DC overlapping characteristics and to be applied at high frequency. Such cores are referred to as Soft Magnetic Metal Powder Cores. 1 is a diagram visually showing the eddy current loss in the soft magnetic bulk material, sheet, powder.

Therefore, in the soft magnetic powder core, the insulating layer formed on the powder surface to influence the characteristics of the core should have the first high electrical resistivity, and the second excellent adhesion, so that the insulating layer should not be destroyed even at high molding pressure. Third, it must be stable even at high stress relaxation heat treatment temperature of 700 ° C. or higher, fourth, it should be able to be formed uniformly regardless of powder form, and fifth thickness control should be possible.

In general, the insulating layer used for the powder soft magnetic core is formed by a phosphate coating method in which the powder is mixed with a phosphate solution to form a phosphate on the surface, or the fine oxide is mixed with the soft magnetic powder to adsorb the oxide on the powder surface. Solid insulating powder mixing method, and a method of coating the polymer resin is mainly used.

However, existing insulating layer forming methods have the following problems. When the core is molded, the powder deforms, leaving a large stress, which greatly reduces the soft magnetic properties. Therefore, the residual stress must be removed by heat treating the core at a high temperature. From this point of view, the phosphate coating method is very simple, but when the core is heat-treated at a temperature of 300 ° C. or higher, the phosphate coating layer starts to decompose and completely decomposes at 600 ° C., thereby not serving as an insulating layer. In principle, the solid insulating powder mixing method is difficult to uniformly coat the powder surface, and in particular, it is difficult to expect a uniform coating because the shape of the waterless powder is very irregular. In the case of the manufacturing method using a polymer resin, it is good to form an insulator, but there is a disadvantage that heat treatment is impossible from the beginning.

As described above, although the core is formed by forming an insulating layer on the metal powder, it is used for various purposes, but each problem also exists. Therefore, in order to overcome the limitations of the conventional insulating layer forming methods and to solve the respective problems, it is necessary to develop a new insulating layer forming technology that is different from the past, which can exceed the performance of current materials.

[Preceding technical literature]

[Non-Patent Documents]

RE Grace and AU Seybolt, “Selective oxidation of Al from an Al-Fe alloy”, J. Elec. Chem. Soc. 1958, 105, pp. 582-585.

T. Nakayama and K. Kaneko, “Selective oxide films lf a 5% aluminum-iron alloy in a low oxygen potential atmosphere” Corrosion, -NACE , 1970, 26. pp. 187-188 .

VK Tolpygo and DR Clarke, “Microstructural evidence for counter diffusion of aluminum and oxygen during the growth of alumina scales”, 5 ^th International conference on the microscopy of oxidation, Aug. 2002; Ireland, pp. 26-28.

Accordingly, an object of the present invention for solving the above problems is to establish an insulating film formation condition by selectively oxidizing any metal component of the alloy powder on the surface of the powder to form a high quality insulating layer and iron loss using the powder. It is to provide a method for producing this low powder core and an alloy powder core produced by the method.

In addition, another object of the present invention by using the Fe-Al alloy powder, one of the soft magnetic materials to selectively oxidize only aluminum on the powder surface to establish the insulating film forming conditions of Al ₂ O ₃ , to form a high-quality insulating layer The present invention provides a powder and a method for producing a powder core having low iron loss using the powder, and an alloy powder core produced by the method.

In order to achieve the above object, the present invention is a solute by heat-treating an alloy powder widely used as a material of electric, electronic and magnetic elements such as motors, actuators, yokes, cores, reactors, heat treatment under a mixed gas atmosphere of hydrogen and water vapor A soft magnetic powder for selectively oxidizing an element to form a high quality insulating layer, and a soft magnetic alloy powder core is produced from the powder.

In addition, the alloy powder core according to the present invention by using the Fe-Al alloy powder of one of the soft magnetic material to selectively oxidize only aluminum to establish the insulating film formation conditions of Al ₂ O ₃ on the surface, low iron loss powder core It is characterized in manufacturing.

The alloy powder according to the present invention for achieving the above object is heat-treated by supplying hydrogen including water vapor to the alloy powder selected for particle size from several hundred μm to several minutes, and has a high affinity for oxygen among the solute elements included in the alloy powder. A part of the first solute element is selectively oxidized, and the oxidized first solute element forms an insulating layer on the outer surface of the alloy powder.

In this case, the first solute element of the alloy powder according to the present invention is silicon (Si), aluminum (Al), magnesium (Mg), chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf) It is characterized by at least one of.

In addition, the alloy powder according to the present invention, the first solute element and gold (Au), platinum (Pt), silver (Ag), nickel (Ni), iron (Fe), copper (Cu), cobalt (Co) At least one of zinc (Zn), tin (Sn), vanadium (V) and manganese (Mn) is characterized in that the solvent element.

On the other hand, the alloy powder manufacturing method according to the present invention for achieving the above object, by supplying hydrogen containing water vapor to the alloy powder selected by particle size in the size of several hundred μm size, heat treatment, solute elements contained in the alloy powder A portion of the first solute element having affinity with heavy oxygen is selectively oxidized, and the oxidized first solute element forms an insulating layer on the outer surface of the alloy powder.

At this time, the first solute element of the alloy powder core according to the present invention, silicon (Si), aluminum (Al), magnesium (Mg), chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf) Method for producing an alloy powder core, characterized in that any one of).

In addition, the alloy powder of the alloy powder core according to the present invention, the first solute element and gold (Au), platinum (Pt), silver (Ag), nickel (Ni), iron (Fe), copper (Cu) , At least one of cobalt (Co), zinc (Zn), tin (Sn), vanadium (V) and manganese (Mn) is characterized in that the solvent element.

In addition, the alloy powder manufacturing method according to the present invention for achieving the above object, the process of placing the particle size of the Fe-Al produced by the gas spray method to -106 mesh in the heat treatment furnace; Hydrogen-vapor mixture gas having a dew point of -17 ° C and -0 ° C was passed through a copper tube maintained at -17 ° C and -0 ° C by passing hydrogen of 500 SCCM through ion exchanged water maintained at 0 ° C to 10 ° C. Making process; And flowing the hydrogen-steam mixture gas into a heat treatment furnace maintained at 800 ° C. to 900 ° C. to heat-treat the Fe-Al powder for 0 to 60 minutes. Characterized in that consists of.

In addition, the alloy powder core according to the present invention for achieving the above object, by supplying hydrogen containing water vapor to the alloy powder selected for particle size of several hundred μm size, heat treatment, oxygen of the solute elements contained in the alloy powder And selectively oxidize a part of the first solute element having a high affinity with the oxidized first solute, and forming the alloy powder having an insulating layer formed on the outer surface of the alloy powder.

According to the present invention, by forming an insulating layer having a high resistivity on the alloy powder by selective oxidation, there is an effect that a process is easy and an alloy powder having a high resistivity having a high specific resistance is formed.

As a result, an alloy powder having a uniform insulation layer with a simple manufacturing process can be manufactured, thereby increasing the quality of the product and lowering the manufacturing cost.

In addition, the present invention can form an insulating layer of a very thin film having a high resistivity and maintain a high magnetic flux density, thereby producing an ultra-small and high-performance electronic device, components and products.

1 is a visual representation of eddy current loss in a soft magnetic bulk material, sheet, and powder

Figure 2 is a device configuration for explaining the manufacturing process of the alloy powder core according to the present invention,

3 is a surface shape in which a hydrogen-steam mixed gas having a dew point of 0 ° C. is flowed into a heat treatment furnace maintained at 900 ° C. in a manufacturing process of an alloy powder core according to the present invention and selectively oxidized Fe-6 wt.% Al powder with time. Picture,

4 is Fe-4 wt% while flowing a hydrogen-vapor mixture gas having a dew point of −17 ° C. in a process of manufacturing an alloy powder core according to the present invention at a temperature of 900 ° C. Cross-sectional photograph of 20 minutes selective oxidation of Al powder,

5 is Fe-4 wt% subjected to selective oxidation heat treatment for 40 minutes while flowing a hydrogen-vapor mixed gas having a dew point of 0 ° C. in a process of manufacturing an alloy powder core according to the present invention in a heat treatment furnace maintained at 900 ° C. FIG. Component mapping photo of Al powder cross section,

6 is Fe-6 wt% subjected to selective oxidation heat treatment of a hydrogen-vapor mixture gas having a dew point of 0 ° C. at 800 ° C. FIG. After making Al powder as a core, a graph measuring density and specific resistance,

7 is a graph showing the core loss according to the oxidation time of the alloy powder core according to the present invention,

8 is a graph showing the change in electrical resistivity and density according to the heat treatment temperature of the core made of phosphate-treated powder of the alloy powder core according to the present invention;

9 is a graph showing the core loss according to the heat treatment temperature of the alloy powder core according to the present invention.

DETAILED DESCRIPTION Hereinafter, detailed descriptions of preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same components in the figures represent the same numerals wherever possible. Specific details are set forth in the following description, which is provided to aid a more general understanding of the present invention. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In particular, in the following description of the alloy powder core and its manufacturing method according to the present invention with reference to the drawings, the alloy will be described as a representative embodiment using Fe-Al. For convenience of explanation, only iron (Fe) and aluminum (Al) are used as an example, and the first solute elements such as aluminum (Al) constituting the alloy powder include silicon (Si), aluminum (Al), and magnesium (Mg). ), Chromium (Cr), titanium (Ti), zirconium (Zr) and hafnium (Hf) may be at least one, and the solvent element such as iron (Fe) forming the alloy powder with the first solute element is gold (Au), platinum (Pt), silver (Ag), nickel (Ni), iron (Fe), copper (Cu), cobalt (Co), zinc (Zn), tin (Sn), vanadium (V) and manganese It may be at least one of (Mn).

Therefore, in the following Fe-Al powder means an alloy powder, the alloy powder core according to the present invention is finally produced an alloy powder treated according to the alloy powder core manufacturing method according to the present invention.

First, Figure 2 is a device configuration for explaining the manufacturing process of the alloy powder core according to the present invention, referring to Figure 2, the manufacturing method of the alloy powder core according to the present invention is a Fe-Al powder prepared by the gas spray method Is selected and oxidized to a particle size of less than 106 mesh in a heat treatment furnace (Furnace).

At this time, in order to remove oxygen remaining in the heat treatment furnace (Furnace) and the pipe, it is purged with high purity nitrogen (N ₂ ). After purging is completed, the hydrogen (N ₂ ) of 500 SCCM passed through ion-exchanged water (Water vapor 1) maintained at 0 ° C. to 10 ° C. is again replaced with a copper pipe (Water vapor 2) maintained at −17 ° C. and −0 ° C. Passing produces a hydrogen-steam mixture with dew points of -17 ° C and -0 ° C, respectively. The mixed gas is flowed into a furnace maintained at 800 ° C or 900 ° C to heat-treat the Fe-Al powder for 0-60 minutes.

Thus, the heat-treated Fe-Al powder is molded. By adding 0.2% of a solid lubricant prior to molding, it is easy to escape from the mold during molding. Molding is carried out at room temperature with a pressure of 1206 MPa in a pressure press to produce a toroidal core having an outer diameter of 12.7 mm, an inner diameter of 7.6 mm and a height of 3.7 mm.

In order to remove residual stress and solid lubricant present in the core after compression molding, the core is heat-treated for 60 minutes in an 800 ° C. heat treatment furnace under a high purity nitrogen atmosphere. Homica coating was used to prevent damage to the heat-treated core. The wire was wound 36 times in the same manner as the primary and secondary wires to the completed core.

FIG. 3 is a photograph showing the surface shape of the hydrogen-steam mixed gas having a dew point of 0 ° C. being oxidized to Fe-6 wt.% Al powder over time while flowing in a heat treatment furnace maintained at 800 ° C. FIG. As shown in FIG. 3, the casting structure appeared in all powders, and the Fe-Al powder which was not heat treated showed a smooth shape, but when selective oxidation heat treatment was performed, Al ₂ O ₃ was formed around the surface of the powder and the heat treatment time increased. (0, 2, 10, 30 minutes) The particles grow larger. Unexpectedly, however, these particles do not appear at the grain boundaries of the cast structure and are evenly distributed on the powder surface, which may be advantageous in producing powder cores.

Figure 4 is Fe-4 wt% flowing hydrogen-vapor mixture gas having a dew point of -17 ℃ flowing in a heat treatment furnace maintained at 900 ℃. It is a cross-sectional photograph which selectively oxidized Al powder for 20 minutes. 4, a thin Al ₂ O ₃ insulating film around the Fe-Al powder is formed, and insulating middle in Fig. Al ₂ O ₃ shown in the surface of Figure 3, but generally forming a continuous insulating layer has a thickness It is not constant.

5 is Fe-4 wt% subjected to selective oxidation heat treatment for 40 minutes while flowing a hydrogen-vapor mixture gas having a dew point of 0 ° C. into a heat treatment furnace maintained at 900 ° C. FIG. As a component mapping of the cross-section of the Al powder, the iron appears evenly, but a lot of aluminum and oxygen is detected on the surface, it can be seen that Al ₂ O ₃ is well formed on the surface.

6 is Fe-6 wt% subjected to selective oxidation heat treatment of a hydrogen-vapor mixture gas having a dew point of 0 ° C. at 800 ° C. FIG. After the Al powder is made of a core, it is a graph measuring density and specific resistance. Referring to FIG. 6, as the selective oxidation heat treatment time increases, the thickness of the film around the powder becomes thick, and thus the density tends to decrease, whereas the resistivity tends to increase. As shown in Fig. 6, when the heat treatment is carried out for 10 minutes, the increase in density is due to the relaxation of the residual stress generated when the powder solidifies, and the decrease in thickness thereafter is caused by the thickening of the insulating layer.

In addition, the increase in the electrical resistivity is due to the thickening of the insulating layer, and if the insulating layer completely surrounds the powder, the resistivity will have an infinite value.

Figure 7 shows the core loss according to the oxidation time, since the effect of eddy current is high at high frequency, the core loss continuously decreases as the heat treatment time increases at 50 kHz. However, at 0.4 and 1 kHz, this tendency is reduced and the loss is very small even after heat treatment for about 2 minutes. The core losses at 0.4, 1, and 50 kHz of the cores prepared with 30 min selective oxidation were 105, 284 and 774 mW / cm ³ , respectively.

The characteristics of the above-described selective oxidized Fe-6 wt.% Al powder were compared with the phosphate-treated powders with reference to FIGS. 8 and 9 below. Figure 8 shows the change in electrical resistivity and density according to the heat treatment temperature of the core made of phosphate treated powder.

As the heat treatment temperature increases, the density increases, and the electrical resistivity shows the lowest value at 700 ° C. Compared with FIG. 7 showing the change in specific resistance and density of the oxidized powder, the density is similar but the electrical resistivity is very high. The core must be heat-treated after molding to relieve the stress that occurs when forming the core. The higher the heat treatment temperature, the softer magnetic properties, especially hysteretic loss, reduce core loss.

9 is a graph showing core loss at 0.4 and 1 kHz according to the heat treatment temperature of a core made of phosphate-treated powder, the lowest core loss when heat-treated at 700 ℃. However, compared to the result of selective oxidation, the core loss is very high. This is shown in detail in Table 1 below. Table 1 compares the core loss of the oxidized Fe-6 wt.% Al powder with that of the phosphate-treated powder.

Table 1

	Core loss (㎽ / cm 3)
	Selective Oxidation	Phosphate- coating
0.4 ㎑	105	185
1 ㎑	284	428
50 ㎑	774	2028

It is known that the phosphate coating layer is destroyed when heat treated at 500 ° C. or higher, and the phosphate insulating layer is completely destroyed when heat treated at 800 ° C. in FIG. 9. However, despite the very high electrical resistivity of the cores heat-treated at 800 ° C, the increased core loss indicates a fatal chemical reaction between the phosphate layer and the powder.

As described above, the alloy powder core manufacturing method according to the present invention has a problem in that the phosphate coating layer is decomposed when the heat treatment temperature of the existing insulating layer forming methods is 300 ° C. or higher, as compared with the existing insulating layer coating methods, and It is difficult to expect the coating, and can solve the disadvantage that the heat treatment is not possible, it is possible to produce an alloy powder core having a simpler and higher performance.

In particular, the alloy powder and powder core manufacturing method according to the present invention, as well as iron alloy powder core, gold (Au), platinum (Pt), silver (Ag), nickel (Ni), copper (Cu), cobalt (Co), Alloy powder and powder core including zinc (Zn), tin (Sn), vanadium (V), manganese (Mn) and the like can be prepared.

In addition, the alloy powder core according to the present invention has a high permeability compared to the conventional soft magnetic powder core can be applied to an ultra-small and high performance electronic device.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims

Hydrogen containing water vapor is heat-treated by supplying hydrogen to the alloy powders of which the particle size is selected to a size of several hundreds of μm to selectively oxidize a part of the first solute element having a high affinity with oxygen among the solute elements included in the alloy powder, The alloy powder, characterized in that the oxidized first solute element forms an insulating layer on the outer surface of the alloy powder.
The method of claim 1, wherein the first solute element,

Alloy powder, characterized in that at least one of silicon (Si), aluminum (Al), magnesium (Mg), chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf).
The method of claim 1, wherein the alloy powder,

The first solute element and gold (Au), platinum (Pt), silver (Ag), nickel (Ni), iron (Fe), copper (Cu), cobalt (Co), zinc (Zn), tin (Sn) , Alloy powder with at least one of vanadium (V) and manganese (Mn).
Hydrogen containing water vapor is heat-treated by supplying hydrogen to the alloy powders of which the particle size is selected to a size of several hundreds of μm to selectively oxidize a part of the first solute element having a high affinity with oxygen among the solute elements included in the alloy powder, The method of claim 1, wherein the oxidized first solute element forms an insulating layer on the outer surface of the alloy powder.
The method of claim 4, wherein the first solute element,

Method for producing an alloy powder, characterized in that any one of silicon (Si), aluminum (Al), magnesium (Mg), chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf).
The method of claim 4, wherein the alloy powder,

The first solute element and gold (Au), platinum (Pt), silver (Ag), nickel (Ni), iron (Fe), copper (Cu), cobalt (Co), zinc (Zn), tin (Sn) , Vanadium (V) and manganese (Mn) is an alloy with at least one of the solvent element, characterized in that the alloy powder production method.
Selecting a particle size of Fe-Al prepared by the gas spray method into a -106 mesh and placing the particle in a heat treatment furnace;

Hydrogen-vapor mixture gas having a dew point of -17 ° C and -0 ° C was passed through a copper tube maintained at -17 ° C and -0 ° C by passing hydrogen of 500 SCCM through ion exchanged water maintained at 0 ° C to 10 ° C. Making process; And

Flowing the hydrogen-steam mixture gas into a heat treatment furnace maintained at 800 ° C. to 900 ° C. to heat-treat the Fe-Al powder for 0 to 60 minutes; Alloy powder manufacturing method, characterized in that consisting of.
Hydrogen containing water vapor is heat-treated by supplying hydrogen to the alloy powders of which the particle size is selected to a size of several hundreds of μm to selectively oxidize a part of the first solute element having a high affinity with oxygen among the solute elements included in the alloy powder, An alloy powder core, wherein the oxidized first solute element is formed by molding an alloy powder having an insulating layer formed on an outer surface of the alloy powder.
The method of claim 8, wherein the first solute element,

Alloy powder core, characterized in that at least one of silicon (Si), aluminum (Al), magnesium (Mg), chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf).
The method of claim 8, wherein the alloy powder,

The first solute element and gold (Au), platinum (Pt), silver (Ag), nickel (Ni), iron (Fe), copper (Cu), cobalt (Co), zinc (Zn), tin (Sn) And an alloy powder core with at least one of vanadium (V) and manganese (Mn).