Method for producing alloy powder

Abstract

To provide a manufacturing method of novel alloy powder capable of suppressing qualitative variation.SOLUTION: A liquid film 20 having a predetermined thickness PT is formed on a base 11 by a high-speed fluid composed of a cooling liquid supplied at high pressure from a nozzle 13 and flowing in a direction of an arrow A at high speed. At this time, the liquid film 20 is applied with a predetermined acceleration in the direction along an arrow B (that is, the thickness direction of the liquid film 20). Next, the molten alloy 25 is supplied to the liquid film 20 formed in this manner as a lump to some extent without dividing into pieces of a size equal to or less than the predetermined thickness PT. When the molten alloy 25 is supplied to the liquid film 20 as a lump to some extent in this way, the molten alloy 25 is divided by the liquid film 20 made of a high-speed fluid into sizes equal to or less than the predetermined thickness PT to form alloy powder, at the same time, the alloy powder is continuously cooled in the liquid film 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing alloy powder.

Background Art

[0002] Generally, as methods for producing alloy powder, a water atomization method and a gas atomization method are known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, alloy powders obtained by the water atomization method or the gas atomization method often have substantial variations in quality.

[0005] Therefore, an object of the present invention is to provide a new method for producing alloy powder capable of suppressing substantial variations.

Means for Solving the Problems

[0006] As a first method for producing alloy powder, the present invention forms a liquid film having a predetermined thickness of 0.1 mm or more with a high-speed fluid composed of a coolant, and a predetermined acceleration of 2.0×10 4 G or more is applied along the thickness direction, supplies the alloy melt to the liquid film without dividing it into sizes below the predetermined thickness, divides the alloy melt into sizes below the predetermined thickness by the high-speed fluid to form alloy powder, and continuously cools the alloy powder in contact with the high-speed fluid in the liquid film using the predetermined acceleration to provide a method for producing alloy powder.

[0007] Further, as a method for manufacturing a second alloy powder, the present invention provides a method for manufacturing a first alloy powder, wherein the liquid film is formed by continuously supplying a coolant from a nozzle onto the inner wall of the drum, the predetermined acceleration is a centrifugal acceleration directed toward the inner wall of the drum and provides a method for manufacturing an alloy powder.

[0008] Further, as a method for manufacturing a third alloy powder, the present invention provides a method for manufacturing a second alloy powder, wherein the initial velocity of the coolant supplied from the nozzle is 80 m / s or more, the predetermined acceleration is 1.0×10 7 G or less and provides a method for manufacturing an alloy powder.

[0009] Further, as a method for manufacturing a fourth alloy powder, the present invention provides a method for manufacturing a third alloy powder, wherein the initial velocity of the coolant is 100 m / s or more and provides a method for manufacturing an alloy powder.

[0010] Further, as a method for manufacturing a fifth alloy powder, the present invention provides a method for manufacturing a third or fourth alloy powder, wherein the predetermined acceleration is 3.0×10 4 G or more and provides a method for manufacturing an alloy powder.

[0011] Further, as a method for manufacturing a sixth alloy powder, the present invention provides a method for manufacturing any one of the third to fifth alloy powders, wherein the predetermined thickness is 0.8 mm or more and provides a method for manufacturing an alloy powder.

[0012] Further, as a method for manufacturing a seventh alloy powder, the present invention provides a method for manufacturing any one of the second to sixth alloy powders, wherein the inner diameter of the drum is 10 mm or more and 100 mm or less and provides a method for manufacturing an alloy powder.

[0013] Also, as a method for manufacturing an eighth alloy powder, the present invention provides a method for manufacturing a seventh alloy powder, wherein the inner diameter of the drum is 20 mm or more and 60 mm or less. A method for manufacturing alloy powder is provided.

[0014] Also, as a method for manufacturing a ninth alloy powder, the present invention provides a method for manufacturing any one of the first to eighth alloy powders, wherein the supply rate of the high-speed fluid is 15 times or more the supply rate of the molten alloy. A method for manufacturing alloy powder is provided.

[0015] Also, as a method for manufacturing a tenth alloy powder, the present invention provides a method for manufacturing any one of the first to ninth alloy powders, wherein the molten alloy is supplied to the liquid film in an oxidizing atmosphere of 100 ppm or more. A method for manufacturing alloy powder is provided.

[0016] Also, as a method for manufacturing an eleventh alloy powder, the present invention provides a method for manufacturing any one of the first to tenth alloy powders, wherein the molten alloy is supplied to the liquid film at an angle of 10° or more and 90° or less. A method for manufacturing alloy powder is provided.

[0017] Also, as a method for manufacturing a twelfth alloy powder, the present invention provides a method for manufacturing any one of the first to eleventh alloy powders, wherein the molten alloy is supplied only to a predetermined region on the liquid film having a diameter of 15 mm or less. A method for manufacturing alloy powder is provided.

Advantages of the Invention

[0018] In the conventional atomization method of the rapid cooling type, after the molten alloy was fragmented with gas, water, etc. and pulverized, it was rapidly cooled with a cooling liquid such as cooling water. However, due to the difference in the cooling rate depending on the size of the fragmented powder particles, and the difference in the dropping points and dropping speeds of each powder particle, there was a difference in the time of cooling in the air until the cooling liquid was reached between the powder particles, resulting in variations in quality. In contrast, in the present invention, the molten alloy is supplied to a liquid film without being fragmented in advance, and the molten alloy is fragmented by a high-speed fluid to form alloy powder and cooled by the liquid film. That is, in the present invention, the fragmentation and cooling of the molten alloy are substantially performed simultaneously, and the occurrence of a difference in the degree of cooling between the powder particles is suppressed. Therefore, according to the present invention, homogenization of the powder particles can be achieved.

[0019] In addition, if the powder particles fragmented by the liquid film are not appropriately cooled, they will collide with the member constituting the bottom of the liquid film before solidification is completed, thereby causing the powder particles to have a deformed shape. To avoid this, a predetermined acceleration in the thickness direction of the liquid film is set to 2.0×10 4 G or more and the predetermined thickness of the liquid film is set to 0.1 mm or more to ensure an appropriate cooling capacity, and thereby solidify the powder particles before reaching the member constituting the bottom of the liquid film. As a result, powder particles that are somewhat uniform can be obtained also in terms of the shape surface.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0021] The method for manufacturing alloy powder according to an embodiment of the present invention generally fragments the molten alloy with a liquid film of a high-speed fluid to form alloy powder and cools it with the liquid film.

[0022] As shown in FIG. 1, in the alloy powder manufacturing apparatus 10 according to the present embodiment, a high-speed fluid composed of a coolant is supplied from a nozzle 13 onto a base 11 at a high pressure and flows at high speed in the direction of arrow A to form a liquid film 20 having a predetermined thickness PT. At this time, a predetermined acceleration is applied to the liquid film 20 along the direction along arrow B (that is, the thickness direction of the liquid film 20).

[0023] Next, the molten alloy 25 is supplied to the liquid film 20 formed in this way from the alloy supply unit 15 without being divided into sizes smaller than the predetermined thickness PT. That is, unlike the conventional rapid cooling type atomization method, the molten alloy is not divided into powder and then rapidly cooled by a liquid film, but the molten alloy 25 is supplied to the liquid film 20 while remaining in a certain mass. When the molten alloy 25 is supplied to the liquid film 20 while remaining in a certain mass in this way, the molten alloy 25 is divided into sizes smaller than the predetermined thickness PT by the liquid film 20 composed of a high-speed fluid, and alloy powder is formed. When the alloy powder comes into contact with the liquid film 20, the alloy powder is cooled thereby, while the coolant around the alloy powder evaporates instantaneously. Here, the liquid film 20 of the present embodiment has a predetermined acceleration. Therefore, even if the coolant around the alloy powder evaporates, the alloy powder is pressed against the coolant of the high-speed fluid and continues to be in contact therewith. In this way, the alloy powder is continuously cooled.

[0024] In the case of the conventional rapid cooling type atomization method, the equipment tends to be large-sized, and in addition to the cost problem that high-pressure gas equipment and gas costs are separately required, since it is cooled to some extent before reaching the liquid film after being divided, there is a problem that the cooling rate after reaching the liquid film decreases. In contrast, in the present embodiment, molten alloy 25 the division and cooling are substantially simultaneously performed within the liquid film 20, and since the difference in the degree of cooling between powder grains is suppressed, homogenization of the powder grains can be realized.

[0025] Furthermore, if the powder particles separated by the liquid film 20 are not properly cooled, they will collide with the base 11 that constitutes the bottom of the liquid film 20 before solidification is complete, thereby causing the powder particles to become irregular in shape. To avoid this, in the present embodiment, the predetermined acceleration in the thickness direction (the direction along arrow B) of the liquid film 20 is set to 2.0×10 4 G or more, and the predetermined thickness PT of the liquid film 20 is set to 0.1 mm or more. When the predetermined acceleration is 2.0×10 4 G or more, sufficient cooling capacity can be obtained. Also, by setting the predetermined thickness PT of the liquid film 20 to 0.1 mm or more, it is possible to suppress the divided droplets from colliding with the inner wall of the tank before solidification and increasing the amount of irregular-shaped powder. In this way, in the present embodiment, the spherical or substantially spherical powder particles are solidified before reaching the base 11 that constitutes the bottom of the liquid film 20. As a result, powder particles with a certain degree of uniformity can be obtained even in terms of the shape surface. Such a method for manufacturing alloy powder according to the present embodiment is particularly suitable for manufacturing soft magnetic powder.

[0026] In order to generate the predetermined acceleration in the liquid film 20, for example, the alloy powder manufacturing apparatus 10a shown in FIG. 2 may be used. The alloy powder manufacturing apparatus 10a in FIG. 2 includes a cylindrical drum 11a, and the inner wall 12a of the drum 11a is used as the base. The liquid film 20 is formed by continuously supplying a coolant from the nozzle 13 onto the inner wall 12a of the drum 11a. When the liquid film 20 is formed in this way, a centrifugal acceleration directed toward the inner wall 12a of the drum 11a is generated in the liquid film 20. This is used as the above-mentioned predetermined acceleration. In this way, by using the centrifugal acceleration as the predetermined acceleration, alloy powder can be efficiently continuously cooled with a simple device configuration.

[0027] Preferably, the initial velocity of the coolant supplied from the nozzle 13 is 80 m / s or more, and the predetermined acceleration is 1.0×107G or less. If the initial velocity of the coolant is less than 80 m / s, the molten alloy 25It has poor ability to break up. As a result, the droplets broken up in the liquid film 20 become larger, and the frequency of deformation during cooling increases, so that the stretched coarse powder increases. That is, it is likely to become irregular-shaped powder. On the other hand, when the initial velocity of the coolant is 80 m / s or more, sufficient breakup ability can be obtained, so that substantially spherical or spherical powder can be obtained.

[0028] In particular, when the initial velocity of the coolant supplied from the nozzle 13 is 100 m / s or more, the powder is further refined, and the amorphousness and magnetic properties are improved. Therefore, it is more preferable that the initial velocity of the coolant is 100 m / s or more. However, when the initial velocity of the coolant supplied from the nozzle 13 exceeds 800 m / s, while the powder itself becomes fine, the number of filamentous ones increases in terms of shape. Therefore, it is more preferable that the initial velocity of the coolant is 800 m / s or less.

[0029] The predetermined acceleration in the liquid film 20 is preferably 3.0×10 4 G or more. Increasing the predetermined acceleration can improve the cooling ability. When a high cooling ability can be realized, there is an advantage that even an alloy with a low amorphous formation ability in terms of composition can be made amorphous.

[0030] Preferably, the predetermined thickness PT is 0.8 mm or more. When the thickness of the liquid film 20 is 0.8 mm or more, the dispersion region of the broken-up droplets in the liquid film 20 expands, so that it is possible to prevent the broken-up droplets from colliding with each other and becoming irregular-shaped. More preferably, the predetermined thickness PT is 15 mm or less. This is because if the predetermined thickness PT is too thick, the water flow velocity difference between the water film surface and the inside of the water film becomes large, so that the broken-up droplets are likely to be stretched while being cooled, and the powder may become irregular-shaped.

[0031] Here, for example, when using the drum 11a as in the alloy powder manufacturing apparatus 10a of FIG. 2, the inner diameteris desirably from 10 mm to 100 mm, more desirably from 20 mm to 60 mm. When the inner diameter of the drum 11a is decreased, the centrifugal acceleration increases, so that the amorphousness of the produced alloy powder is improved. Specifically, the effect is enhanced by making the inner diameter of the drum 100 mm or less, and powder with good amorphousness can be obtained even with a composition having an Fe content of 80 at% or more. When the inner diameter of the drum is 60 mm or less, the amorphousness of the produced alloy powder is further improved. On the other hand, the smaller the inner diameter of the drum, the greater the effect of improving the amorphousness, but in practical use, when it is less than 10 mm, it is difficult to supply the molten alloy 25 . Therefore, the inner diameter of the drum is preferably 10 mm or more, and in order to more stably supply the molten alloy 25 to the liquid film 20, the inner diameter of the drum is preferably 20 mm or more.

[0032] When the supply rate of the molten alloy 25 is decreased with respect to the supply rate of the high-speed fluid composed of the coolant, the rise in the water temperature is suppressed. Further, the turbulence of the high-speed fluid disappears, and alloy powder can be stably produced and cooled. From such a viewpoint, the supply rate of the high-speed fluid is preferably 15 times or more the supply rate of the molten alloy 25 , and more preferably 40 times or more in order to more stably produce alloy powder. Note that the speed of the molten alloy 25 causes no problem in production even with discharge by free fall due to its own weight.

[0033] There is no particular limitation on the atmosphere when supplying the molten alloy 25 to the liquid film 20. For example, there is no problem even in the air with respect to the spheroidization of the alloy powder. Further, in an inert atmosphere, in addition to the spheroidization of the alloy powder, it is also possible to suppress the oxidation of the alloy powder. However, considering productivity and manufacturing cost, the supply of the molten alloy 25 to the liquid film 20 is preferably performed in an oxidation atmosphere of 100 ppm or more.

[0034] There is no particular limitation on the atmosphere when supplying the molten alloy 25When supplying, it can be carried out more stably by making an angle. Also, by increasing the breaking angle, the alloy powder can be refined. From such a viewpoint, the molten alloy should form an angle of 10° or more and 90° or less with respect to the liquid film 20. 25 It is preferable to supply it.

[0035] Molten alloy 25 When supplying the molten alloy to the liquid film 20, it is preferable to supply it only to a predetermined area on the liquid film 20 with a diameter of 15 mm or less. In this way, by supplying the molten alloy to an area below the predetermined area, the quality of the alloy powder can be stabilized, and the size of the drum 11a etc. used to form the liquid film 20 can be reduced. The predetermined area is more preferably 10 mm or less in diameter. 25 It becomes possible, and miniaturization such as the drum 11a used for forming the liquid film 20 becomes possible. The predetermined area is more preferably 10 mm or less in diameter.

[0036] (Examples 1 - 19 and Comparative Examples 1 - 3) By the method for producing an alloy powder according to the above-described embodiment of the present invention, alloy powders were produced under a plurality of conditions as shown in Table 1 below, and the obtained alloy powders were evaluated. with manufactured and evaluated for the obtained alloy powder.

[0037]

Table 1

[0038] According to Table 1, when the inner diameter of the drum exceeded 100 mm as in Comparative Example 1, the shape of the powder particles became irregular and the characteristics were also poor. Also, when the initial velocity of the cooling liquid was less than 80 m / s as in Comparative Examples 2 and 3, the shape of the powder particles became irregular and the characteristics were also poor. On the other hand, the alloy powders of Examples 1 - 19 had spherical or almost spherical powder particle shapes, good amorphous properties, small coercive force, and had good characteristics. In particular, as understood from Examples 8 - 10 and Comparative Example 2, when the initial velocity of the cooling liquid was 100 m / s or more, the powder became finer, and the amorphous properties and magnetic properties were improved.

[0039] (Examples 21 - 28 and Comparative Example 21) The relationship between the supply rate of the high-speed fluid composed of the coolant and the supply rate of the molten alloy with respect to the high-speed fluid was verified under a plurality of conditions shown in Table 2 below, and the obtained alloy powder was evaluated. The alloy compositions of Examples 21 to 28 and Comparative Example 21 were Fe 84.35 P 8.5 B 6.5 Cu 0.65 and the initial velocity of the coolant was 200 m / s.

[0040] [Table 2]

[0041] According to Table 2, when the supply rate of the high-speed fluid composed of the coolant was 15 times or more the supply rate of the molten alloy, the amorphous property of the obtained alloy powder was good. Furthermore, when the supply rate of the high-speed fluid was 40 times or more the supply rate of the molten alloy, the particle shape was good. [Explanation of Signs]

[0042] 10, 10a Alloy powder manufacturing apparatus 11 Base 11a Drum 12a Inner wall 13 Nozzle 15 Alloy supply section 20 Liquid film PT Predetermined thickness 25 Molten alloy

Claims

1. A high-speed fluid composed of a coolant, which is a liquid film having a predetermined thickness of 0.1 mm or more and on which a predetermined acceleration of 2.0×10 ４ G or more is applied along the thickness direction to form a liquid film, Supply the molten alloy to the liquid film without dividing it into sizes below the specified thickness, Use the high-speed fluid to divide the molten alloy into sizes below the specified thickness to form alloy powder, and continue to cool the alloy powder in contact with the high-speed fluid within the liquid film using the specified acceleration Method for manufacturing alloy powder.

2. The method for manufacturing alloy powder according to Claim 1, The liquid film is formed by continuously supplying a coolant from a nozzle onto the inner wall of the drum, The specified acceleration is the centrifugal acceleration towards the inner wall of the drum Method for manufacturing alloy powder.

3. The method for manufacturing alloy powder according to Claim 2, The initial velocity of the coolant when supplying the coolant from the nozzle onto the inner wall of the drum is 80 m / s or more, The specified acceleration is 1.0×10^7 G or less Method for manufacturing alloy powder.

4. The method for manufacturing alloy powder according to Claim 3, The initial velocity of the coolant is 100 m / s or more Method for manufacturing alloy powder.

5. The method for manufacturing alloy powder according to Claim 3 or Claim 4, The predetermined acceleration is 3.0×10 ４ G or more Method for manufacturing alloy powder.

6. The method for manufacturing alloy powder according to any one of Claims 3 to 5, The specified thickness is 0.8 mm or more Method for manufacturing alloy powder.

7. The method for manufacturing alloy powder according to any one of Claims 2 to 6, The inner diameter of the drum is 10 mm or more and 100 mm or less Method for manufacturing alloy powder.

8. The method for manufacturing alloy powder according to Claim 7, The inner diameter of the drum is 20 mm or more and 60 mm or less Method for manufacturing alloy powder.

9. The method for manufacturing alloy powder according to any one of Claims 1 to 8, The supply rate (kg / min) of the high-speed fluid is 15 times or more the supply rate (kg / min) of the molten alloy Method for manufacturing alloy powder.

10. The method for manufacturing alloy powder according to any one of Claims 1 to 9, Supply the molten alloy to the liquid film in an oxidation atmosphere with an oxygen concentration of 100 ppm or more Method for manufacturing alloy powder.

11. The method for manufacturing alloy powder according to any one of Claims 1 to 10, Supply the molten alloy to form an angle of 10° or more and 90° or less with respect to the liquid film Method for manufacturing alloy powder.

12. The method for manufacturing alloy powder according to any one of Claims 1 to 11, The molten alloy is supplied only to a predetermined region on the liquid film having a diameter of 15 mm or less. Method for producing alloy powder.

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