JP6565941B2 - Method for producing soft magnetic iron powder - Google Patents

Description

  The present invention relates to a method for producing soft magnetic iron powder using a water atomizer. In particular, the present invention relates to a method for improving the cooling rate when an amorphous soft magnetic iron powder mainly composed of Fe-based elements (Fe, Ni and Co) is produced by water atomization.

  There is an atomizing method as a method for producing metal powder. This atomizing method includes a water atomizing method in which a metal powder is obtained by dividing (atomizing) a molten metal flow by injecting a high-pressure water jet into the molten metal flow, and a gas atomizing method in which an inert gas is injected instead of the water jet. and so on.

  In recent years, amorphous soft magnetic materials have been developed. In order to obtain an amorphous structure, it is necessary to rapidly solidify the molten metal powder. For this purpose, a technique has been proposed in which a molten metal is divided by water or an inert gas and then cooled by water. However, both of them are complicated in structure and are not suitable for industrial mass production. In addition, a water atomization technique for dividing and cooling a molten metal flow with water has been used for a long time, but the required rapid solidification cannot be obtained with the conventional simple water atomization.

  On the other hand, as an amorphous soft magnetic material, for example, Non-Patent Document 1 has developed a nanocrystalline soft magnetic alloy having excellent magnetic properties. This nanocrystalline soft magnetic alloy realizes excellent magnetic properties by subjecting an amorphous alloy produced by rapid cooling to heat treatment to precipitate iron crystals refined to about 10 nm. Typical Fe-based nanocrystalline soft magnetic alloys include those based on (Fe, Ni, Co) -Si-P-B-Cu. This material exhibits a high saturation magnetic flux density that is not found in conventional amorphous soft magnetic materials, and the tendency is remarkable as the total amount of Fe or Fe, Ni, and Co increases. However, the addition of Cu for the precipitation of fine iron crystals and the increase in the amount of Fe-based metal, and the cooling rate required to obtain an amorphous material, increase the precision. Control is required.

Conventionally, many proposals have been made as methods for producing metal powder by rapid cooling. For example, Patent Document 1 describes a method for producing a metal powder in which the cooling rate until solidification is 10 ⁵ K / s or more when the metal powder is obtained by cooling and solidifying while scattering molten steel. In the technique described in Patent Document 1, the above-described cooling rate is obtained by bringing the molten steel that has been scattered into contact with the coolant flow generated by swirling the coolant along the inner wall surface of the cylindrical body. It is said.

JP 2010-150587 A

Materia, vol. 14, no. 6, P. 392 (Akihiro Makino, Katsuhito Yoshizawa)

  All of the conventional techniques including the technique described in Patent Document 1 have a complicated structure and inferior industrial mass productivity as compared with a simple water atomizing technique.

  Furthermore, the above prior art is not suitable for producing soft magnetic iron powders such as (Fe, Ni, Co) -Si-P-B-Cu-based nanocrystalline soft magnetic materials that require strict control.

  Moreover, it is difficult for the prior art to obtain a high amorphization rate even with a relatively large particle size.

  INDUSTRIAL APPLICABILITY The present invention is a water atomization method with excellent industrial productivity, and it is difficult to increase the amorphization rate, and is preferably applicable to high Fe concentration amorphous, especially nanocrystalline soft magnetic alloys. An object of the present invention is to provide a method for producing a soft magnetic iron powder that can be preferably applied to the production of a soft magnetic iron powder having a diameter.

  In the conventional method of producing soft magnetic iron powder by water atomization, with regard to the action of water used for dividing the molten metal stream to cool the metal powder at the same time, attention is paid only to the cooling action at the atomization point, and the film boiling is destroyed. Etc.

  As a result of intensive studies by the inventors, in the past, development was made with an emphasis only on the cooling rate, but it was found that the viewpoint of continuation of cooling is important when scaling up to an industrial scale. Thus, the present invention has been completed. That is, if the cooling in atomization is excessively concentrated at one point, although a large cooling rate can be obtained instantaneously, subsequent cooling becomes difficult, resulting in a stable high amorphization rate. It has been found that there is no such thing, and has led to the present invention. Specifically, the above-mentioned problem can be solved if a molten steel metal flow divided by high-pressure water injected at a relatively high injection speed of 50 m / s or more is subjected to direct cooling treatment with high-pressure water over a length of 25 mm or more. . The present invention provides the following.

  [1] In the chamber, high-pressure water that collides with a region having a length Ld in the vertical direction of the molten metal flow falling vertically from the molten metal injection nozzle is injected to divide the molten metal flow into a metal powder, and A method for producing a soft magnetic iron powder by cooling a metal powder and producing a soft magnetic iron powder having an amorphization ratio of 90% or more, wherein the molten metal stream and the high-pressure water are in contact with each other at the time of the collision. A method for producing soft magnetic iron powder, wherein Ld (contact length) is 25 mm or more and 250 mm or less, and the injection speed of the high-pressure water is 50 m / s or more and 350 m / s or less.

  [2] The method for producing a soft magnetic iron powder according to [1], wherein an atmosphere of at least a part of the chamber including an installation location of the molten metal injection nozzle is set to a negative pressure of 0.03 MPa or more and 0.09 MPa or less. .

[3] The chamber has a cylindrical constricted portion through which the metal powder being cooled passes below the molten metal injection nozzle, and a cross-sectional area perpendicular to the axial direction in the constricted portion is minimized. The soft magnetism according to [2], wherein the negative pressure is adjusted by adjusting a water flow rate density at a position of 0.1 m ³ / m ² · s to 2.0 m ³ / m ² · s. Manufacturing method of iron powder.

[4] The method for producing a soft magnetic iron powder according to any one of [1] to [3], wherein a cross section perpendicular to the falling direction of the molten metal flow is circular, and a circle diameter of the circle is 4 mm or less. 5] The method for producing a soft magnetic iron powder according to any one of [1] to [3], wherein a cross section perpendicular to a falling direction of the molten metal flow is an ellipse, and a minor axis of the ellipse is 4 mm or less.

  [6] The soft magnetic iron powder according to any one of [1] to [3], wherein a cross section perpendicular to a falling direction of the molten metal flow is a rectangle, and a length of a short side of the rectangle is 4 mm or less. Production method.

  [7] In the soft magnetic iron powder, the total atomic fraction of Fe, Ni, and Co exceeds 76.0 at%, and the atomic fraction of Cu is 0.1 at% or more and 2.0 at% or less [ 1]-[6] The manufacturing method of the soft-magnetic iron powder in any one of.

  [8] The soft magnetic iron powder is a (Fe, Ni, Co) SiPBCu-based nanocrystalline soft magnetic material having a total atomic fraction of Fe, Ni and Co of more than 82.5 at% and less than 86.0 at%. Yes, The manufacturing method of the soft magnetic iron powder in any one of [1]-[6] whose average particle diameter is 5 micrometers or more.

  Since the manufacturing method of the soft magnetic iron powder of the present invention is a simple method, it is a manufacturing method with high productivity (industrial mass productivity) of the soft magnetic iron powder.

  In addition, the method for producing soft magnetic iron powder of the present invention can be preferably applied to high Fe concentration amorphous, especially nanocrystalline soft magnetic alloys.

  Moreover, the manufacturing method of the soft magnetic iron powder of this invention is providing the manufacturing method of the soft magnetic iron powder which can be applied preferably also when manufacturing the soft magnetic iron powder of a comparatively big particle size.

  The production method of the present invention can be used for water atomization production of any conventionally known amorphous soft magnetic material. In addition, in recent years, in addition to the non-patent document 1, Journal of Applied Physics 105, 013922 (2009), Japanese Patent No. 4288687, Japanese Patent No. 4310480, Japanese Patent No. 4815014, WO-2010-084900, JP-A 2008- As disclosed in Japanese Patent No. 231534, Japanese Patent Application Laid-Open No. 2008-231533, Japanese Patent No. 2710938, etc., heteroamorphous materials and nanocrystalline materials having a high magnetic flux density have been developed. The present invention is very advantageously adapted to the production of soft magnetic iron powder having a high Fe-based component concentration by water atomization. In particular, when the content of Fe-based components exceeds 82.5% in atomic% (at%) in the nanocrystalline material, and further exceeds 83.5%, the amorphization rate is 90% at a particle size of 5 μm or more. Therefore, the effect of the present invention that makes it possible to increase the amorphization rate to 90% or more is remarkable. In addition, when applied to a composition range outside the above range, there is an effect that an amorphous powder can be obtained more easily and stably than a large-diameter powder.

It is a figure which shows typically an example of a soft-magnetic iron powder manufacturing apparatus. It is a graph which shows the relationship between the injection speed of high pressure water, and the distance from a spray nozzle. It is a graph showing the relationship between contact length, the injection speed of high-pressure water, and an amorphization rate. It is a schematic diagram which shows the apparatus using the negative pressure effect | action by cylindrical space. It is a schematic diagram which shows the apparatus using the negative pressure effect | action by cylindrical space which is a modification of FIG.

  Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment.

  FIG. 1 is a diagram schematically showing an example of a soft magnetic iron powder production apparatus that can be used for carrying out the soft magnetic iron powder production method of the present invention.

  The apparatus shown in FIG. 1 includes a melting furnace 1, a tundish 2 that pours molten metal 3 that is molten steel melted in the melting furnace 1, and a molten metal that drops the molten metal 3 poured into the tundish 2 as a molten metal stream 11. It has an injection nozzle 4, a nozzle header 5 for injecting high-pressure water 7, a spray nozzle 6 for injecting high-pressure water 7, and a chamber 13 covering the entire apparatus. In addition, the structure which is not necessary for description of this invention is abbreviate | omitted. In addition, the high pressure water said here points out the case where an injection pressure is 10 Mpa or more. Further, the present invention provides a soft magnetic iron powder in which the atomic fraction of Fe, Ni and Co exceeds 76.0 at% in total, and the atomic fraction of Cu is 0.1 at% or more and 2.0 at% or less. As a manufacturing method, a method of manufacturing a soft magnetic iron powder which is a (Fe, Ni, Co) SiPBCu-based nanocrystalline soft magnetic material having a total atomic fraction of Fe, Ni and Co of more than 82.5 at% and less than 86 at% preferable. In order to produce these soft magnetic iron powders, it is necessary to adjust the composition of the molten metal to a desired composition.

  The molten metal stream 11 falling from the molten metal injection nozzle 4 becomes a metal powder 12 by collision with the high-pressure water 7 sprayed from the spray nozzle 6. The metal powder 12 is cooled while being dropped by the surrounding water. The metal powder solidified by cooling is soft magnetic iron powder. Although only two spray nozzles 6 are shown in FIG. 1, it is preferable that 4 to 16 spray nozzles are arranged at equal intervals on the circumference. In the example of FIG. 1, eight are arranged. The number of spray nozzles is not particularly limited.

  In the present invention, Ld (contact length 8), which is the length of contact between the molten metal stream 11 and the high-pressure water 7 at the time of collision, is 25 mm or more and 250 mm or less. Preferably they are 40 mm or more and 150 mm or less. A position at which the high-pressure water 7 starts to collide with the molten metal flow 11 is defined as an atomization start point 9, and a position at which the collision between the high-pressure water and the molten metal flow 11 is terminated is defined as an atomization end point 10. The length from the atomization start point 9 to the atomization end point 10 is the contact length 8. The molten metal stream 11 first contacts the high pressure water 7 at the atomization start point 9 and cooling starts. The contact length 8 can be set by giving a certain spread without directly irradiating the high-pressure water 7 locally. Specifically, the contact length 8 employs a nozzle that expands in the direction of travel of the molten metal flow 11, adjusts the angle, distance, etc. of the spray nozzle 6 with respect to the molten metal flow 11, It can be controlled by using a plurality of overlapping spray nozzles 6. However, using a plurality of nozzles that inject high-pressure water toward the contact length 8 is likely to cause fluctuations in speed, so it is recommended to increase the contact length without using the spray nozzle 6 with overlapping injection areas. Is done. As a method for expanding the contact length without using the spray nozzle 6 in which the spray regions overlap, there is a method using a preliminary guide. In this method, high pressure water is sprayed from the spray nozzle onto the surface of the preliminary guide and collided, thereby changing the traveling direction of the high pressure water and expanding the injection width in the molten metal flow falling direction. This is a method of causing high-pressure water to collide with water. In the case of this method, since the speed of the high-pressure water changes due to the collision of the high-pressure water with the preliminary guide, it is necessary to adjust the injection speed of the high-pressure water when colliding with the molten metal flow. Further, if water atomization is performed under the conditions of the present invention, the molten metal flow 11 proceeds without being greatly changed in its original outer shape while being divided, so the injection range of the high-pressure water 7 determined in advance offline and the water The suitability of the contact length can be determined based on the contact length with the surface of the virtual molten metal flow 11 that is not divided.

  In the present invention, the injection speed of the high-pressure water 7 injected into the molten metal stream 11 is set to 50 m / s or more and 350 m / s or less. Note that the injection speed of the high-pressure water 7 is the speed at which the high-pressure water 7 reaches the surface of the molten steel metal stream 11. As an example, as shown in FIG. 2, the injection speed of the high-pressure water is attenuated according to the distance from the spray nozzle. Therefore, not only the selection of the water nozzle and the control of the water pressure but also the adjustment according to the attenuation is necessary. In addition, although the speed measurement of high-pressure water can be performed with a laser Doppler meter, it is desirable to perform with a high-speed camera in this speed region. The nature of the high-pressure water may be a continuous water stream or a droplet, but a continuous water stream is recommended because the change in velocity due to the shearing action with air is small.

The effects of the present invention will be described below. An important configuration for obtaining the effect of the present invention is that the contact length 8 is 25 mm or more and 250 mm or less, and the injection speed of the high-pressure water 7 injected into the molten metal stream 11 is 50 m / s or more and 350 m / s or less. It is to do. In FIG. 3, the graph showing the relationship between contact length, the injection speed of high-pressure water, and an amorphization rate is shown. Acquisition of the graph of FIG. 3 was performed as follows. An alloy having an atomic ratio of Fe ₈₃ Si ₃ B ₈ P ₅ Cu ₁ is blended and melted completely at a melting furnace 1 at about 1600 ° C. to form a molten metal 3, which is gradually heated to a predetermined temperature in the melting furnace 1. After cooling, it was poured into tundish 2. Before pouring the molten metal into the tundish 2, the high-pressure water 7 was jetted from the spray nozzle 6 in advance. Then, the molten metal flow 11 was dropped from the molten metal injection nozzle 4 and the atomization was started by colliding the high pressure water 7 with this. The exit side shape of the molten metal injection nozzle 4 at this time was a circle having a diameter of 3 mm. In carrying out a series of experiments, the molten metal injection rate (flux) was adjusted to be approximately 300 kg / hour and the water amount was constant at 11 m ³ / hour. Under these conditions, by changing various water nozzle header divergence angles and configurations and arrangements, the injection speed of the high-pressure water is changed from 50 m / s to 800 m / s, and the contact length is changed to a maximum of 800 mm. The change of the amorphization rate of the obtained soft magnetic iron powder was confirmed. As shown in the graph of FIG. 3, the contact length 8 is 25 mm or more and 250 mm or less, and the injection speed of the high-pressure water 7 injected into the molten metal flow 11 is 50 m / s or more and 350 m / s or less. Thus, the amorphization rate can be sufficiently increased. Specifically, when the contact length 8 is less than 25 mm, it is considered that continuous cooling cannot be performed and it is difficult to sufficiently increase the amorphization rate. If the contact length 8 exceeds 250 mm, it is difficult to adjust the position of the spray nozzle 6, and further, there is a problem that the effect of amorphization is not improved or lowered. Even if the contact length 8 is in the above range, if the spray speed is less than 50 m / s, a sufficient cooling speed cannot be obtained locally, which is not appropriate. On the other hand, when the injection speed exceeds 350 m / s, scattering of the molten metal flow 11 becomes significant, and subsequent cooling is not stably performed. Therefore, as shown in FIG. 1, an upper limit is set in order that the molten steel metal flow 11 travels over an effective contact length 8 with the high-pressure water 7 on an extension of the original cylindrical shape while being divided. In the contact length 8 described above, it is important that the high-pressure water 7 collides with the molten metal flow 11 at an injection speed of 50 m / s or more and 350 m / s or less, and before and after the contact length 8, the injection speed is 50 m / s. Even if there is a region that is less than s, the effect of the present invention is not diminished, but since it becomes useless water, it is not economically preferable.

  Further, by adjusting the contact length 8 and the injection speed, the amorphous ratio can be sufficiently increased even for amorphous Fe having a high Fe concentration, particularly soft magnetic iron powder of a nanocrystalline soft magnetic alloy.

  In addition, by adjusting the contact length 8 and the jetting speed, a soft magnetic iron powder having a sufficiently high amorphization rate can be manufactured even when a soft magnetic iron powder having a relatively large particle size is manufactured. In addition, the comparatively large particle diameter said here is an average particle diameter of 10 micrometers or more and about 200 micrometers or less as a standard.

  In addition, as described above, the adjustment of the contact length 8 and the injection speed does not require a complicated structure, so that soft magnetic iron powder having a high amorphization rate can be easily manufactured. Excellent productivity. In addition, in order to improve productivity, the molten metal stream 11 is provided as a continuous fluid instead of a mist spray. This is because it is premised on the scale of industrial production. If the molten metal flow 11 is used instead of the atomized spray, a commercial production scale of about 50 kg to 2000 kg / h can be achieved.

  Hereinafter, important ones among preferable conditions will be described.

  In the above example, the exit side shape of the molten metal injection nozzle 4 is a circle having a diameter of 3 mm, and the cross section perpendicular to the falling direction of the molten metal flow 11 is a circle. In the present invention, the shape of the cross section perpendicular to the falling direction of the molten metal flow 11 is not particularly limited. The effect of the present invention can be obtained regardless of whether it is circular, elliptical, rectangular or the like. In order to obtain stable division and cooling, the circle diameter is preferably 4 mm or less, the ellipse is preferably 4 mm or less, and the rectangle is preferably 4 mm or less. Although it is difficult to reduce the length of the cross section of the molten metal flow on an industrial production scale from the viewpoint of production volume, the negative pressure action described later and the molten metal flow are non-cylindrical (dropping of the molten metal flow 11). By setting the cross-sectional shape orthogonal to the direction to a shape other than a circle such as an ellipse or a rectangle, the substantial molten metal flow rate can be increased. It can be considered that the shape of the cross section orthogonal to the falling direction of the molten metal flow 11 is determined by the outlet shape of the molten metal injection nozzle 4 in the scope of the present invention.

  Next, when a molten metal flow that is a continuous fluid is formed by injection, the driving force of the injection is suction of 0.03 MPa or more and 0.09 MPa or less depending on the difference from the atmospheric pressure in addition to the molten metal hydrostatic pressure. The combined use of negative pressure is preferable for stable amorphization and consolidation of the obtained powder. The reason why a stable amorphization can be obtained is not necessarily clear, but when atomization is performed using only the hydrostatic pressure as the driving force for molten metal injection, the fluctuation of the molten metal surface and the distribution are low because the injection driving force is small. It is presumed that the action of the resistance greatly affects the molten metal flow and thus makes it difficult to maintain a stable molten metal flow over the contact length range. In addition, a method for increasing the driving force of the injection by the back pressure of the inert gas was also examined. However, the method of applying a high pressure to a high-temperature container is not recommended for a preferable production scale of about 50 kg to 2000 kg / h as in the present invention, and is not recommended because a stable dividing effect in contact length cannot be obtained. . On the other hand, when the molten metal flow is dropped by using a negative pressure action in combination, a stable and high amorphous state can be obtained.

  In particular, the soft magnetic iron powder obtained when the negative pressure action due to the cylindrical space is used together is excellent in compactness and is suitable for use in a dust core or the like. This effect is considered to be reflected in the compactness through the grain shape and the like obtained by the shearing force between the molten metal and the atmospheric gas acting at an accelerated speed. FIG. 4 shows an apparatus that utilizes a negative pressure action caused by a cylindrical space. The constricted portion 14 of this device corresponds to a cylindrical space. The device also has a spare guide 15.

  The constricted portion 14 is a cylindrical portion that is provided below the molten metal injection nozzle and through which the metal powder being cooled passes. The axial direction of the constricted portion 14 shown in FIG. 4 is the same as the falling direction of the molten metal flow. Moreover, since the constriction part 14 of FIG. 4 is cylindrical shape, the shape of the cross section orthogonal to the falling direction of the molten metal flow of the constriction part 14 is a circle of a fixed magnitude | size irrespective of the position of the said dropping direction. As long as a negative pressure action can be generated, the axial direction of the constricted portion 14 may not be the same as the falling direction of the molten metal flow, and the shape of the cross section orthogonal to the falling direction of the molten metal flow of the constricted portion 14. May not be constant regardless of the position in the dropping direction.

The negative pressure action is preferably adjusted by the water flow rate density at the position where the area of the cross section perpendicular to the falling direction of the molten metal flow in the constricted portion 14 is minimized. Specifically, it is desirable to adjust the water flow rate density in the range of 0.1 m ³ / m ² · s to 2.0 m ³ / m ² · s. What is important about the above pressure action (negative pressure action) is to apply a sufficiently large negative pressure with respect to fluctuations in the hydrostatic pressure, and at least a pressure action of 0.03 MPa (about 3000 mmH ₂ O). Preferably there is. Below this, it is difficult to obtain a stable amorphous property. On the other hand, if the negative pressure exceeds 0.09 MPa, the flow of the molten metal flow becomes unstable, so the effect is small. In the present invention in which the injection speed and contact length of the high-pressure water are specified, the water flow rate density is 0.1 m ³ / m ² · s or more and 2.0 m ³ in order to obtain 0.03 MPa or more and 0.09 MPa or less. / M ² · s or less may be adjusted. If the pressure is less than 0.1 m ³ / m ² · s, the negative pressure is insufficient and a good compacting action cannot be obtained. If the value exceeds 2.0 m ³ / m ² · s, the cross-sectional area with respect to the amount of water is too small and the flow of water In extreme cases, this is not recommended because it may cause water clogging called blowing up.

  The negative pressure can be measured using a manometer or the like with the nozzle portion closed without flowing molten metal at the molten metal flow nozzle outlet or inlet, and can be adjusted based on this measurement result. it can.

  The preliminary guide 15 in FIG. 4 has a plate shape and is provided below the spray nozzle 6. The preliminary guide 15 is installed such that the plate surface is inclined from the horizontal and the plate surface collides with high-pressure water ejected from the spray nozzle 6. The functions required of the preliminary guide 15 are to change the direction of the high-pressure water and to widen the width of the molten metal flow-down direction of the high-pressure water. If it has this function, it may not be plate-shaped and the installation location is not limited.

  In the case of the apparatus shown in FIG. 4, since there is the constricted portion 14, it may be difficult to make the contact length 8 longer than a predetermined length. In this case, if the preliminary guide 15 is used, the width of the high-pressure water in the dropping direction is widened, and the contact length 8 is easily increased.

  FIG. 5 shows an apparatus having a constricted portion 14 in which the cross section perpendicular to the falling direction of the molten metal flow 11 is rectangular (short side: 3 mm, long side: 12 mm), and the cross section perpendicular to the axial direction is a square of 50 mm × 50 mm. It was. The contact length was ensured by carrying out the two-dimensional spray after making the spray nozzle 6 into two nozzles in which the injection direction is directed toward the molten metal flow 11. Even if the cylindrical shape changes, the same effect as in the case of FIG. 4 can be obtained.

  Using the apparatus shown in FIG. 1, soft magnetic iron powder was produced under the conditions shown in Table 1 while monitoring the temperature of the molten metal so that the molten metal temperature was equal to or higher than the melting point at the time of atomization.

  For each Fe-based powder (soft magnetic iron powder) obtained in this example and the comparative example, after removing dust other than the soft magnetic iron powder, the average particle diameter was measured with a laser diffraction / scattering type particle size distribution analyzer. The particle size was measured and the amorphization rate was calculated by the X-ray diffraction method. Table 1 shows the results. In the table, the apparent density is a density value measured according to JIS-Z2504 and is an index of consolidation.

Although the apparent density is not so large, all of the samples carried out under the conditions of the present invention show a large amorphization ratio exceeding 90%. Fe _85.3 Si ₃ B ₈ P ₃ Cu _0.7 and Fe _83.1 B ₁₀ P ₆ Cu _0. The total amount of Fe-based elements (Fe, Ni, Co) exceeds 82.5 at% in atomic fraction _. although the contact length at ₇ Cr _0.2 is only about 97% of an amorphous ratio is 95 in the case of 32 mm, in the case of more preferred contact length 130mm are obtained a value of 100%.

  Soft magnetic iron powder was manufactured under the conditions shown in Table 2 using the apparatus shown in FIG. The amorphous ratio and average particle size were evaluated by the same method as in Example 1.

Those implemented under the conditions of the present invention all show a large amorphization rate exceeding 90%. Fe _85.3 Si ₃ B ₈ P ₃ Cu _0.7 and Fe _83.1 B ₁₀ P ₆ Cu _0.7 Cr _{0.2 in which} (Fe, Ni, Co) exceeds 82.5 at% in atomic fraction. However, in the case where the contact length is 38 mm, the amorphization ratio is about 95 to 97%, but in the case of a more preferable contact length of 80 mm, a value of 100% is obtained. Further, the essential constituent requirements of the present invention are satisfied, and the suction negative pressure is 0.03 MPa or more and 0.09 MPa or less, and the water flow rate density at this time is 0.1 m ³ / m ² · s or more and 2.0 m ³ / It can be seen that when the condition of m ² · s or less is satisfied, a large apparent density of 4.0 g / cm ³ or more is obtained.

  Soft magnetic iron powder was manufactured under the conditions shown in Table 3 using the apparatus shown in FIG. The amorphous ratio and average particle size were evaluated by the same method as in Example 1.

Those implemented under the conditions of the present invention all show a large amorphization rate exceeding 90%. Fe _85.3 Si ₃ B ₈ P ₃ Cu _0.7 and Fe _83.1 B ₁₀ P ₆ Cu _0.7 Cr with Fe-based elements (Fe, Ni, Co) exceeding 82.5 at% in atomic fraction _{At 0.2} , the amorphization rate remains at about 92 to 92% when the contact length is 35 mm. However, when the contact length is 55 mm, a value of 100% is obtained. Further, the essential constituent requirements of the present invention are satisfied, and the suction negative pressure is 0.03 MPa or more and 0.09 MPa or less, and the water flow rate density at this time is 0.1 m ³ / m ² · s or more and 2.0 m ³ / It can be seen that when the condition of m ² · s or less is satisfied, a large apparent density of 4.0 g / cm ³ or more is obtained.

DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Tundish 3 Molten metal 4 Molten metal injection nozzle 5 Nozzle header 6 Spray nozzle 7 High pressure water 8 Contact length 9 Atomization start point 10 Atomization end point 11 Molten metal flow 12 Metal powder 13 Chamber 14 Neck part 15 Preliminary guide

Claims (8)

In the chamber, high-pressure water that collides with the region of the vertical length Ld of the molten metal flow falling vertically from the molten metal injection nozzle is injected, the molten metal flow is divided into metal powder, and the metal powder is A method for producing soft magnetic iron powder that cools and produces soft magnetic iron powder having an amorphization ratio of 90% or more,
Ld (contact length), which is the length of contact between the molten metal stream and the high-pressure water at the time of the collision, is 25 mm or more and 250 mm or less,
A method for producing soft magnetic iron powder, wherein the jet speed of the high-pressure water is 50 m / s or more and 350 m / s or less.   The method for producing soft magnetic iron powder according to claim 1, wherein at least a part of the atmosphere in the chamber including the place where the molten metal injection nozzle is installed is set to a negative pressure of 0.03 MPa or more and 0.09 MPa or less. The chamber has a cylindrical constriction under the molten metal injection nozzle through which the metal powder being cooled passes,
The water flow rate density at the position where the cross-sectional area perpendicular to the axial direction is minimized in the constricted portion is adjusted in the range of 0.1 m ³ / m ² · s to 2.0 m ³ / m ² · s, The method for producing soft magnetic iron powder according to claim 2, wherein the negative pressure is adjusted.   The method for producing a soft magnetic iron powder according to any one of claims 1 to 3, wherein a cross section perpendicular to the falling direction of the molten metal flow is circular, and a circle diameter of the circle is 4 mm or less.   The method for producing a soft magnetic iron powder according to any one of claims 1 to 3, wherein a cross section perpendicular to the falling direction of the molten metal flow is an ellipse, and the minor axis of the ellipse is 4 mm or less.   The method for producing soft magnetic iron powder according to any one of claims 1 to 3, wherein a cross section perpendicular to the falling direction of the molten metal flow is a rectangle, and a length of a short side of the rectangle is 4 mm or less.   The soft magnetic iron powder has a total atomic fraction of Fe, Ni and Co of more than 76.0 at%, and an atomic fraction of Cu of 0.1 at% or more and 2.0 at% or less. The method for producing a soft magnetic iron powder according to any one of claims 6 to 10.   The soft magnetic iron powder is a (Fe, Ni, Co) SiPBCu-based nanocrystalline soft magnetic material having a total atomic fraction of Fe, Ni and Co of more than 82.5 at% and less than 86.0 at%, and has an average grain size The method for producing soft magnetic iron powder according to claim 1, wherein the diameter is 5 μm or more.