Manufacturing method for Fe-SiB thick plate rapid solidification alloy thin strips

Abstract

A method for producing an alloy thin strip, wherein an Fe-Si-B-based alloy melt, which essentially contains iron (Fe), boron (B) and silicon (Si), is spouted from a tapping nozzle onto the surface of a cooling roll and the cooling roll is rotated such that the surface speed thereof is 15 to 50 m / sec, thereby rapidly cooling the alloy melt on the surface of the cooling roll so as to produce an alloy thin strip. With respect to this method for producing a rapidly solidified alloy thin strip, the tapping nozzle is provided with slits that are arranged in two to four rows in the formation direction of the alloy thin strip, while having a width of not less than 0.2 mm but less than 1.2 mm; the cooling roll has a curvature of not less than 8 × 10-4 but less than 2 × 10-3; and a rapidly solidified alloy thin strip, which has an average thickness of not less than 30 μm but less than 70 μm and an average width of not less than 50 mm but less than 200 mm, while containing 90% by volume or more of an amorphous alloy structure, is produced by flowing a cooling water that is not less than 5°C but less than 60°C through the cooling roll at a cooling water flow rate of not less than 0.3 m3 / min but less than 20 m3 / min.

Description

[Technical Field]

[0001] This invention relates to a method for producing thin strips of Fe-Si-B thick plate rapid solidification alloy. [Background technology]

[0002] In recent years, there has been a market demand for materials with low iron loss and high saturation magnetic flux density for various passive components such as inductors and reactors, as well as transformers, used as electronic components. Soft magnetic materials, primarily composed of iron (Fe), boron (B), and silicon (Si), such as iron-based amorphous materials and iron-based nanocrystalline materials, are known to have high magnetic permeability and lower iron loss compared to electrical steel sheets. Fe-Si-B rapidly solidified alloy strips, approximately 17 μm to 25 μm thick, produced using such soft magnetic materials by rapid molten metal solidification, are used as winding cores in inductors and transformers, and demand for them as a replacement for conventional electrical steel sheets is expanding year by year.

[0003] Furthermore, iron-based amorphous alloys possess superior soft magnetic properties compared to electromagnetic steel sheets (silicon steel sheets) used as laminated cores for motors, with iron loss approximately 1 / 10 and permeability more than three times greater. Therefore, in addition to their use in the inductors and transformers mentioned above, their use as wound cores for motors is expected to contribute to the miniaturization and increased efficiency of motors. However, iron-based amorphous alloys with a thickness of approximately 17 μm to 25 μm are only applied to a limited number of motors as wound cores due to reasons such as the inability to perform the punching process necessary for laminated cores, as well as a decrease in the space factor.

[0004] Fe-Si-B amorphous alloys have traditionally been used for 10 4 ~10 6Amorphous structures could only be obtained in rapidly solidified alloy strips of about 17 to 25 μm in thickness at extremely fast solidification rates of K / sec. However, Non-Patent Literature 1 discloses that by adding phosphorus (P), the solidification rate can be reduced, and iron-based amorphous alloy strips of about 50 μm in thickness can be obtained. However, phosphorus-added alloys not only cause a decrease in the saturation magnetic flux density Bs due to the addition of phosphorus, but the phosphorus component volatilizes during alloy melting, causing significant contamination inside and outside the molten metal rapid cooling equipment, and they may also be highly flammable. Therefore, there are still few examples of applications in industrial fields.

[0005] Patent documents 1 and 2 disclose a method for producing rapidly cooled alloy strips with a thickness (50 μm or more) sufficient for punching, using a multi-slit method in which molten alloy is dispensed from multiple slit nozzles onto a rotating cooling roll. However, patent documents 1 and 2 do not disclose the specifications or operating parameters of a manufacturing apparatus for mass-producing iron-based amorphous alloys of such thickness at low cost while stably maintaining the homogeneity and consistent quality of the amorphous alloy.

[0006] Patent documents 3 and 4 disclose a method for producing an iron-based amorphous alloy with a thickness of 30 μm or more by alternately dispensing molten metal from a multi-slit nozzle to two cooling rolls. The manufacturing apparatus used in this method requires two cooling rolls, which not only significantly increases manufacturing and running costs, but also makes it extremely difficult to control the gap between the nozzle tip and the cooling roll surface, which greatly affects the thickness and rapid cooling state of the iron-based amorphous alloy, compared to a normal single-roll molten metal rapid cooling apparatus with only one cooling roll.

[0007] Patent Document 5 discloses a cooling roll used in a single-roll molten metal rapid cooling apparatus for manufacturing iron-based amorphous alloys with a thickness of 30 μm or more. However, the complex structure of the cooling water channel leads to high manufacturing costs. Furthermore, while Patent Document 5 describes increasing the cooling water flow rate as the thickness of the amorphous foil strip increases, the optimal amount of cooling water for the roll is not clarified. In addition, while it is recommended to use different diameters for the rolls depending on the thickness of the amorphous thin strip, preparing multiple cooling rolls and drive mechanisms according to the thickness significantly increases the manufacturing cost of the apparatus, making it difficult to apply as a mass production apparatus when considering production efficiency.

[0008] Patent document 6 discloses a method for manufacturing thin metal strips that uses a porous nozzle to suppress uneven thickness of the thin metal strip when producing wide, rapidly cooled thin strips. The invention of Patent Document 6 is characterized by the shape of the nozzle opening, but it has the problem of high nozzle processing costs due to the difficulty of processing, making it difficult to use at a mass production level.

[0009] Patent Document 7 discloses a method for producing a wax strip with a thickness of 50 to 200 μm using a single-roll molten metal rapid cooling apparatus. However, the wax strip obtained by this method is a crystalline Ni-based alloy, and therefore does not disclose a manufacturing technology for a rapidly solidified alloy having an amorphous structure with a thickness of about 50 μm.

[0010] Patent Document 8 discloses a method for manufacturing Fe-based amorphous alloy strips with wavy irregularities formed on the free surface by a single-roll method, with the aim of reducing hysteresis loss, which is the main cause of iron loss in wide amorphous alloy strips. Although Patent Document 8 describes the temperature distribution in the width direction of the molten metal nozzle and the roughness of the cooling roll surface, it does not disclose a manufacturing technology for iron-based rapidly solidified alloys having an amorphous structure that can be applied to laminated iron cores.

[0011] Thus, as a technology for manufacturing an Fe-Si-B-based rapidly solidified alloy with a thickness of 30 μm or more using a conventional slit nozzle, in addition to improving the amorphous formation ability of the alloy by adding phosphorus (P), a proposal has been made to use a multi-slit molten metal discharging nozzle in which a plurality of rows of slits are arranged perpendicular to the rotation direction of the cooling roll. However, when the molten metal discharging rate increases, such as by discharging the molten metal from a plurality of rows of slits, it becomes difficult to rapidly cool the molten alloy with the cooling roll, and it becomes difficult to obtain an amorphous structure. For this reason, as solutions to this problem, measures such as devising the cooling water channel structure of the cooling roll and arranging two cooling rolls in parallel and alternately supplying the molten metal have been conventionally devised. However, since all of these measures complicate the configuration of the molten metal rapid cooling device, a molten metal rapid cooling technology for stably mass-producing an Fe-Si-B-based rapidly solidified alloy with a thickness of 30 μm or more at a low cost has not been established, and there has been no achievement of being provided to the market at the mass production level until now.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Non-Patent Documents

[0013]

Non-Patent Document 1

[0014] Currently, Fe-Si-B amorphous materials used in transformers and other applications have a thickness of around 20 μm, which is not a suitable thickness for use in laminated iron cores. Furthermore, existing technologies that enable the production of thicker Fe-Si-B amorphous materials either result in a decrease in soft magnetic properties or present problems in terms of productivity and cost. For this reason, there is a strong demand in the electronic components market for a method that enables the production of thicker Fe-Si-B amorphous materials regardless of alloy composition, and for the mass production of inexpensive, high-performance alloy strips made from Fe-Si-B amorphous materials.

[0015] Therefore, the present invention aims to provide a method for producing Fe-Si-B thick plate rapid solidification alloy thin strips that are suitable as laminated iron cores for motors and the like, and that can be easily mass-produced at low cost. [Means for solving the problem]

[0016] Figure 6 is a schematic diagram of the apparatus used in a conventional method for manufacturing Fe-Si-B rapidly solidified alloy strips. As shown in Figure 6, the molten alloy supplied from the nozzle 52 of the molten metal container 51 to the surface of the cooling roll 54 is rapidly cooled on the cooling roll 54 and then peeled off from the cooling roll 54 to obtain a rapidly solidified Fe-Si-B alloy strip. On the surface of the cooling roll 54, primary cooling is performed to rapidly cool the molten alloy to obtain an amorphous structure, so as to quickly pass between the melting point and the glass transition temperature of the alloy and crystallization does not occur. The rapidly solidified alloy that has undergone primary cooling is in a supercooled state and is therefore susceptible to recrystallization due to self-heating caused by the latent heat of solidification.

[0017] Therefore, in the conventional mass production process of Fe-Si-B rapid solidification alloys, the molten metal ejected onto the surface of the cooling roll 54 adheres to the surface of the cooling roll 54 for about half its circumference during primary cooling, and the latent heat of solidification is removed. The rapid solidification alloy strip 55, which consists of an amorphous structure formed by primary cooling, is then subjected to secondary cooling in a solid state and peeled off from the cooling roll 54.

[0018] In the conventional technology described above, the molten metal is brought into contact with approximately half the circumference of the cooling roll 54 in order to prevent recrystallization caused by the release of the latent heat of solidification in the supercooled rapidly solidified alloy strip 55 when it is detached from the cooling roll 54 immediately after rapid solidification. However, if the distance from the molten metal supply position to the detachment position on the surface of the cooling roll 54 is increased in this way, the time until the molten metal is supplied again to the detachment position due to the rotation of the cooling roll 54 is shortened. As a result, if the molten metal supply rate per unit time is high, the supply of molten metal to the cooling roll 54 will be repeated before the surface temperature of the cooling roll 54 has sufficiently decreased. Consequently, there was a risk that the surface temperature of the cooling roll 54 would rise too high, making it impossible to continue rapid cooling of the molten metal.

[0019] This invention clarifies the heat removal capacity required of cooling rolls through various tests in order to form a rapidly solidified alloy structure that does not undergo recrystallization due to the release of latent heat of solidification. Specifically, this invention clarifies the preferred conditions for the surface speed, curvature, cooling water volume, and cooling water temperature of the cooling rolls according to the size of the rapidly solidified alloy strip, thereby enabling the easy and low-cost mass production of Fe-Si-B molten rapidly solidified alloy strips that can be suitably used for laminated iron cores in motors and the like, without complicating the configuration of the manufacturing equipment.

[0020] The object of the present invention is a method for producing an alloy strip by ejecting molten Fe-Si-B alloy, which is essential for iron (Fe), boron (B), and silicon (Si), from a pouring nozzle onto the surface of a cooling roll, and rotating the cooling roll at a surface speed of 15 m / sec to 50 m / sec to rapidly cool the molten alloy on the surface of the cooling roll, wherein the pouring nozzle has slits with a width of 0.2 mm to less than 1.2 mm along the direction of formation of the alloy strip. in line The cooling roll is formed such that the curvature 9×10 -4 Therefore, cooling water at 5°C to less than 60°C is used in a 0.3 m 3 / min or more 20 m 3 This is achieved by a method for producing Fe-Si-B thick plate rapid solidification alloy strips, which involves passing cooling water through the cooling roll at a rate of less than 1 / min, thereby producing a rapid solidification alloy strip with an average thickness of 30 μm or more and less than 70 μm, an average width of 50 mm or more and less than 200 mm, and containing 90 volume percent or more of amorphous alloy structure. In this method for producing Fe-Si-B thick plate rapid solidification alloy strips, it is preferable that each slit of the hot water outlet nozzle is the same length within the range of 45 mm or more and less than 200 mm, with a spacing between them of 0.5 mm or more and less than 5.0 mm, and that the distance from the tip of the hot water outlet nozzle to the surface of the cooling roll is preferably 0.15 mm or more and less than 30 mm.

[0022] In the above-described manufacturing methods for Fe-Si-B thick plate rapid solidification alloy thin strips, the cooling roll is preferably made of a material mainly composed of Cu, Mo, or W, has an arithmetic mean surface roughness Ra of 10 nm or more and less than 20 μm, is formed to be 50 mm or more and less than 400 mm longer than the length of the slit, and has a thickness of 5 mm or more and less than 50 mm from the surface to the cooling water channel.

[0023] The ejection pressure of the molten alloy ejected from the slit is preferably 2 kPa or more and less than 60 kPa.

[0024] The aforementioned molten alloy has a compositional formula of T loo-x-y-z-n Qx Si y M n (T is at least one element selected from the group consisting of Fe, Co, and Ni, a transition metal element that necessarily contains Fe, Q is one or more elements selected from the group consisting of B and C and necessarily contains B, M is one or more elements selected from the group consisting of P, Al, Ti, V, Cr, Mn, Nb, Cu, Zn, Ga, Mo, Ag, Hf, Zr, Ta, W, Pt, Au, and Pb), and the composition ratios x, y, and n are respectively 5 ≦ x < 20 atomic%, 2 ≦ y < 15 atomic%, 0 ≦ n < 10 atomic%, and it is preferable that the composition ratio C / (B + C) of Q satisfies 0 or more and less than 0.2.

[0025] By the method for producing a thick-plate rapidly solidified alloy ribbon of the Fe—Si—B system described above, a thick-plate rapidly solidified alloy ribbon of the Fe—Si—B system containing 90% by volume or more of an amorphous structure with a thickness of 30 μm or more and less than 70 μm, which can be used as a laminated core that is easy to apply to motors and the like, can be obtained.

[0026] Further, after processing the above-mentioned thick-plate rapidly solidified alloy ribbon of the Fe—Si—B system into a desired shape by punching, wire cutting, laser cutting, or the like, a laminated core can be obtained using methods such as resin adhesion or caulking. The produced laminated core can also be further processed by wire cutting, laser cutting, or the like to obtain a split core that can be used for motors.

Advantages of the Invention

[0027] According to the method for producing a thick-plate rapidly solidified alloy ribbon of the Fe—Si—B system of the present invention, a thick-plate rapidly solidified alloy ribbon of the Fe—Si—B system suitable as a laminated core for motors and the like can be easily mass-produced at low cost.

Brief Description of the Drawings

[0028] [Figure 1] It is a schematic configuration diagram of an apparatus used in the method for producing a thick-plate rapidly solidified alloy ribbon of the Fe—Si—B system according to an embodiment of the present invention. [Figure 2]Figure 1 is an enlarged view showing the main parts of the device, where (a) is a cross-sectional view and (b) is a bottom view. [Figure 3] This is a schematic diagram illustrating the details of a method for manufacturing a Fe-Si-B thick plate rapid solidification alloy thin strip according to one embodiment of the present invention. [Figure 4] Figure 1 is an enlarged view showing other key parts of the device, where (a) is a longitudinal section and (b) is a cross-sectional view of (a) AA. [Figure 5] This is an enlarged view of the main parts of an apparatus used in a method for producing Fe-Si-B thick plate rapid solidification alloy thin strips according to another embodiment of the present invention, where (a) is a cross-sectional view and (b) is a bottom view. [Figure 6] This is a schematic diagram of the apparatus used in the conventional method for manufacturing Fe-Si-B rapidly solidified alloy strips. [Figure 7] This is the X-ray diffraction pattern of a Fe-Si-B rapidly solidified alloy thin strip obtained in one embodiment of the present invention. [Figure 8] This is the X-ray diffraction pattern of a Fe-Si-B rapidly solidified alloy thin strip obtained in another embodiment of the present invention. [Figure 9] This is the X-ray diffraction pattern of a Fe-Si-B rapidly solidified alloy thin strip obtained in yet another embodiment of the present invention. [Figure 10] This is the X-ray diffraction pattern of a Fe-Si-B rapidly solidified alloy thin strip obtained in one comparative example of the present invention. [Figure 11] This is the X-ray diffraction pattern of a Fe-Si-B rapidly solidified alloy thin strip obtained in another comparative example of the present invention. [Figure 12] This is the X-ray diffraction pattern of a Fe-Si-B rapidly solidified alloy thin strip obtained in yet another comparative example of the present invention. [Modes for carrying out the invention]

[0029] [Alloy composition] The alloy molten metal used in the method for producing Fe-Si-B thick plate rapid solidification alloy strips in this embodiment has a compositional formula of T loo-x-y-z-n Q x Si y M nIt is represented as follows: Q is one or more elements selected from the group consisting of B and C, and must contain B. M is one or more elements selected from the group consisting of P, Al, Ti, V, Cr, Mn, Nb, Cu, Zn, Ga, Mo, Ag, Hf, Zr, Ta, W, Pt, Au, and Pb. The composition ratios x, y, and n are 5 ≤ x < 20 atomic%, 2 ≤ y < 15 atomic%, and 0 ≤ n < 10 atomic%, respectively. The composition ratio C / (B+C) of Q is 0 or greater and less than 0.2.

[0030] Transition metal T, which contains Fe as an essential element, occupies the remaining content of Q, Si, and M. Desired hard magnetic properties can be obtained by substituting a portion of Fe with one or two of Co and Ni, which are also ferromagnetic elements. However, if the amount of substitution for Fe exceeds 30%, it will lead to a significant decrease in magnetic flux density, so the amount of substitution is limited to the range of 0% to 30%.

[0031] When the composition ratio x of Q(=B+C) falls below 5 atomic%, the amorphous formation ability decreases significantly, and α-Fe precipitates during rapid cooling and solidification of the molten metal. On the other hand, in the case of soft magnetic compositions, when the composition ratio x exceeds 20 atomic%, the proportion of Fe decreases, which reduces the magnetic flux density and makes it difficult to obtain high-performance soft magnetic materials. For this reason, the composition ratio x is between 5 atomic% and less than 20 atomic%. Preferably, the composition ratio x is between 7 atomic% and less than 19 atomic%, and more preferably between 8 atomic% and less than 19 atomic%.

[0032] As the substitution rate of C for B in Q increases, the melting point of the molten alloy decreases, reducing the amount of refractory material used during rapid solidification, thus suppressing process costs related to rapid solidification. However, if C / (B+C) exceeds 0.2, the amorphous formation ability decreases, and α-Fe precipitates on the roll surface side of the rapidly solidified alloy due to non-uniform nucleation. In this case, α-Fe is oriented in the plane of the rapidly solidified alloy strip, and the α-Fe(200) peak becomes large. This is undesirable because even if the volume ratio of α-Fe is 10% or less and the remainder is an amorphous structure, it becomes an initiation point for cracking and chipping during punching. For this reason, C / (B+C) is 0 or more and less than 0.2, preferably 0 or more and less than 0.15, and even more preferably 0 or more and less than 0.1.

[0033] Si is an effective element for improving amorphous formation ability and increasing the magnetic permeability of iron-based boron-based rapid solidification alloys when added simultaneously with Fe and B. However, if the amount of Si added (y) exceeds 15 atomic%, the saturation magnetic flux density (Bs) decreases significantly, so y should be kept below 15 atomic%. Furthermore, from the viewpoint of improving magnetic permeability, y should be 2 atomic% or more. More preferably, y should be 2.5 atomic% or more and less than 12 atomic%.

[0034] The addition of M improves the ability to form amorphous materials and refines the metallic structure during rapid solidification, thereby improving productivity during rapid solidification. However, if the composition ratio n of M exceeds 10 atomic%, it leads to a decrease in the saturation magnetic flux density Bs, so n is limited to 0 atomic% or more and less than 10 atomic%. Preferably, n is 0 atomic% or more and less than 7 atomic%, and more preferably 0 atomic% or more and less than 5 atomic%.

[0035] [Rapid Cooling and Solidification Equipment for Molten Alloys (Single-Roll Molten Metal Rapid Cooling Equipment)] Figure 1 is a schematic diagram of a single-roll molten metal quenching apparatus used in a method for producing Fe-Si-B thick plate quenched solidification alloy strips according to one embodiment of the present invention. The single-roll molten metal quenching apparatus 1 shown in Figure 1 comprises a melting furnace 2, a molten metal storage container 5, and a cooling roll 8.

[0036] The melting furnace 2 supplies molten alloy 3, which is made by melting the raw materials, to the storage container 5 by the rotation of the tilting shaft 4. The storage container 5 is equipped with a dispensing nozzle 6 at its bottom, and the molten alloy 3 is ejected from a slit 7 formed at the lower end of the dispensing nozzle 6 onto the surface (outer surface) of the cooling roll 8. The cooling roll 8 rapidly cools the molten alloy in contact with its surface by supplying cooling water to its interior, forming a rapidly solidified alloy strip 9.

[0037] In this single-roll molten metal rapid cooling apparatus 1, the slits 7 of the molten metal outlet nozzle 6 are multi-slits formed in two rows along the formation direction of the rapidly solidified alloy strip 9. A single-roll molten metal rapid cooling apparatus 1 equipped with such multi-slits is preferably used for producing Fe-Si-B thick plate rapidly solidified alloy strips with a thickness of 30 μm or more and less than 70 μm and a width of 50 mm or more and less than 200 mm. Rapidly solidified alloy strips of this size are suitable, for example, for the manufacture of laminated iron cores applied to EV motors, compressors, generators, etc.

[0038] Figure 2 is an enlarged view of the molten metal outlet nozzle 6 of the apparatus shown in Figure 1, where (a) is a cross-sectional view and (b) is a bottom view. The width W1 of the slit 7 shown in Figure 2(a) is set to 0.2 mm or more and less than 1.2 mm. If the width is less than 0.2 mm, the flow of molten metal passing through the slit 7 is obstructed, increasing the likelihood of nozzle blockage. On the other hand, if the width is 1.2 mm or more, the rate of molten metal outlet supplied to the cooling roll becomes too large, and the molten metal cannot be sufficiently cooled by the cooling roll, which may prevent the desired amorphous structure from being obtained. Considering the machinability and accuracy of the slit, the width W1 of the slit 7 is more preferably 0.3 mm or more and less than 1.0 mm, and even more preferably 0.3 mm or more and less than 0.8 mm. The widths W1 of multiple slits 7 may be the same or different from each other.

[0039] The length L1 of the slit 7 shown in Figure 2(b) can be appropriately selected depending on the width of the cooling roll and the required core size of the motor, etc., and is not necessarily limited. However, if the length is less than 45 mm, the application fields as a laminated core are limited, while if the length is 200 mm or more, the molten metal pouring rate supplied to the cooling roll 8 becomes too large, and the molten metal cannot be sufficiently cooled by the cooling roll 8, which may prevent the desired amorphous structure from being obtained. Therefore, the length L1 of the slit 7 is preferably 45 mm or more and less than 200 mm, and considering productivity including running costs and the cost of the single-roll molten metal rapid cooling device, it is more preferably 45 mm or more and less than 170 mm, and even more preferably 45 mm or more and less than 150 mm. It is preferable that the lengths L1 of multiple slits 7 are the same.

[0040] The depth D1 of the slit 7 shown in Figure 2(a) is determined based on the thickness of the bottom of the molten metal nozzle 6. If it is less than 2 mm, insufficient strength of the bottom is likely to occur, while if it is 15 mm or more, the possibility of nozzle blockage increases due to the decrease in the temperature of the molten metal passing through the slit 7. Therefore, the depth D1 of the slit 7 is preferably 2 mm or more and less than 15 mm, more preferably 3 mm or more and less than 12 mm, and even more preferably 3 mm or more and less than 10 mm, considering the stability (straightness) of the molten metal discharge.

[0041] In this embodiment, the slits 7 are arranged in two rows, but they may also be arranged in three or four rows along the formation direction of the rapidly solidified alloy strip 9. If more than four rows of slits 7 are arranged, the total molten metal pouring rate, which is the sum of all the slits 7, becomes too large, making it difficult to cool the molten metal sufficiently with the cooling rolls and thus difficult to obtain an amorphous structure. Therefore, the number of slits 7 is preferably two to four. Considering the homogeneity of the rapidly solidified structure, the number of slits 7 is more preferably two to three, and considering the controllability of the molten metal rate and production efficiency assuming continuous operation, it is even more preferable to have two rows.

[0042] As shown in Figure 2(b), if the spacing S1 of the slits 7 is less than 0.5 mm, processing is difficult, while if it is 5 mm or more, it becomes difficult to obtain a rapidly solidified alloy strip with the desired thickness. Therefore, the spacing S1 of the slits 7 is preferably 0.5 mm or more and less than 5.0 mm, preferably 1.0 mm or more and 5.0 mm or less considering the possibility of the slits falling off when the molten metal is poured, and more preferably 1.0 mm or more and 3.0 mm or less considering the homogeneity of the rapidly solidified alloy structure.

[0043] In Figure 1, the molten metal supplied from the molten metal outlet nozzle 6 to the cooling roll 8 forms a paddle on the surface of the cooling roll 8, causing a rapid cooling and solidification reaction of the molten metal. Therefore, the formation of an appropriate paddle is important. If the distance d from the tip of the molten metal outlet nozzle 6 to the surface of the cooling roll 8 is 30 mm or more, paddle formation will not be stable. On the other hand, if it is less than 0.15 mm, it is difficult to keep the distance d constant due to the thermal expansion of the cooling roll 8. Therefore, a distance d of 0.15 mm or more and less than 30 mm is preferable. Considering the equipment cost for precisely controlling the distance d, a distance d of 0.3 mm or more and less than 30 mm is more preferable, and considering the homogeneity of the rapidly solidified alloy structure, a distance d of 0.3 mm or more and less than 20 mm is even more preferable.

[0044] As shown in Figure 4, the molten metal supplied to the surface of the cooling roll 8 moves from the pouring position P directly below the slit 7 of the pouring nozzle 6 to the detachment position Q where it is separated from the cooling roll 8 as a rapidly solidified alloy strip 9. During this movement, primary cooling occurs to rapidly cool the molten alloy to a supercooled liquid state, and secondary cooling occurs to remove the latent heat of solidification of the supercooled liquid and prevent recrystallization. The distance Δs from the pouring position P to the detachment position Q needs to be sufficient to complete the primary and secondary cooling described above. However, since the surface temperature of the cooling roll 54 needs to be sufficiently reduced while the detachment position Q rotates back to the pouring position P, it is preferable that the rotation angle Δα of the cooling roll 8 from the pouring position P to the detachment position Q is small enough that the distance between the pouring position P and the detachment position Q can be considered a straight line. In this case, the radius R of the cooling roll 8 can be calculated using the following formula. R=lim Δs→0 |Δs / Δα|=|ds / dα|

[0045] When the cooling roll 8 is rotated at a surface speed of 15 m / sec to 50 m / sec, Δs can be determined from the time required for primary and secondary cooling, thereby determining a preferred numerical range for the diameter 2R of the cooling roll 8. The preferred value of Δs depends on the size of the rapidly solidified alloy strip 9. When obtaining a rapidly solidified alloy strip 9 with an average thickness of 30 μm or more and less than 70 μm, and an average width of 50 mm or more and less than 200 mm, the diameter 2R of the cooling roll 8 is 1000 mm or more and less than 2500 mm. Considering the homogeneity of the rapidly solidified alloy structure, 1500 mm or more and less than 2500 mm is preferred, and considering the constraints on processing equipment and manufacturing costs of cooling rolls manufactured by forging methods, etc., 1500 mm or more and less than 2300 mm is more preferred.

[0046] Since the curvature κ of the cooling roll 8 is the reciprocal of the radius R, the curvature κ when obtaining a rapidly solidified alloy strip 9 with an average thickness of 30 μm or more and less than 70 μm, and an average width of 50 mm or more and less than 200 mm, is 8 × 10⁻⁶. -4 The above 2 x 10 -3 It is less than 8 × 10 -4 The above 1.3 × 10 -3 Less than 9 × 10 -4 The above 1.3 × 10 -3 Less than is preferable.

[0047] To complete primary and secondary cooling within the distance Δs described above, the amount and temperature of the cooling water in the cooling roll 8 are also important factors. Figure 4 is a schematic diagram showing an example of the cooling roll 8, where (a) is a longitudinal section view and (b) is an AA section view. The cooling water supplied to the rotation axis 81 of the cooling roll 8 from one end (IN side) spreads radially along the flow path 82, cools the entire surface of the cooling roll 8, then merges and is discharged from the other end (OUT side) of the rotation axis 81. When obtaining a rapidly solidified alloy strip 9 with an average thickness of 30 μm or more and less than 70 μm and an average width of 50 mm or more and less than 200 mm, the amount of cooling water is 0.3 m 3 If the cooling water volume falls below 20 m³ / min, it becomes difficult to complete the primary and secondary cooling on the surface of the cooling roll 8, while the cooling water volume is 20 m³ / min. 3If the flow rate exceeds 0.3 m³, the surface temperature of the cooling roll 8 does not rise during molten metal cooling, and because the temperature difference ΔT between the IN side and OUT side of the cooling roll 8 is small (for example, less than 1°C), the paddles formed on the surface of the cooling roll 8 become unstable. Therefore, the cooling water flow rate should be 0.3 m³. 3 / min or more 20 m 3 The single-roll molten metal rapid cooling device 1, which is less than / min and capable of mass production assuming continuous operation, is 0.5 m 3 / min or more 20 m 3 Preferably less than / min, and 0.5 m 3 / min or more than 15 m 3 Less than / min is even preferable.

[0048] The temperature of the cooling water in the cooling roll 8 affects the adhesion between the molten alloy and the cooling roll 8. If the cooling water temperature falls below 5°C, the adhesion between the molten alloy and the cooling roll 8 is impaired, reducing the heat removal capacity of the cooling roll 8. On the other hand, if the temperature is above 60°C, it may induce failure of the pump supplying the cooling water to the cooling roll 8. Therefore, the cooling water temperature should be between 5°C and 60°C. To further improve the adhesion between the molten alloy and the cooling roll 8, the lower limit of the cooling water temperature is particularly important, preferably between 15°C and 60°C, and more preferably between 30°C and 60°C.

[0049] Furthermore, the adhesion between the molten alloy and the cooling roll 8 is also affected by the material of the cooling roll 8. Considering the thermal conductivity and melting point of the material, the cooling roll 8 is preferably made of a material mainly composed of Cu, Mo, or W, and considering equipment costs and running costs, a material mainly composed of Cu is preferable. A material mainly composed of Cu includes not only alloys in which the Cu content exceeds 50% by mass, but also pure copper (the same applies to materials mainly composed of Mo or W).

[0050] Since the surface roughness of the cooling roll 8 also affects the adhesion between the molten alloy and the cooling roll 8, it is preferable to have an arithmetic mean roughness Ra of the cooling roll surface of 10 nm or more and less than 20 μm. Considering production efficiency and quality, Ra is more preferably 50 nm or more and less than 10 μm, and even more preferably 100 nm or more and less than 10 μm.

[0051] The axial length L2 of the cooling roll 8 shown in Figure 4(a) is preferably 50 mm or more and less than 400 mm longer than the length of the slit 7 shown in Figure 2(b). Considering the cooling capacity and procurement costs of the cooling roll, it is more preferably 100 mm or more and less than 300 mm longer than the length of the slit 7, and even more preferably 100 mm or more and less than 200 mm longer.

[0052] The heat removal capacity of the cooling roll 8 from the molten alloy is also affected by the thickness T2 from the surface of the cooling roll 8 to the flow path 82, as shown in Figure 4(a). If the thickness T2 is less than 5 mm, it becomes difficult to maintain the mechanical strength of the cooling roll 8. On the other hand, if the thickness T2 is 50 mm or more, the surface temperature of the cooling roll 8 in contact with the molten alloy locally exceeds the melting point, which may cause the rapidly solidified alloy to weld to the surface of the cooling roll 8, making it impossible to continue rapid cooling of the molten metal. Therefore, a thickness T2 of the cooling roll 8 of 5 mm or more and less than 50 mm is preferable. Considering wear due to roll polishing after the rapid cooling of the molten metal, a thickness T2 of 10 mm or more and less than 50 mm is more preferable, and considering the operational stability of the rapid cooling process, 10 mm or more and less than 40 mm is even more preferable.

[0053] As described above, paddles are generated when the molten alloy ejected from the slit 7 of the molten alloy nozzle 6 is pressed against the surface of the cooling roll 8. However, if the pressing pressure of the molten alloy is low, it is difficult to generate the desired paddles on the surface of the cooling roll 8. Therefore, it is preferable that the ejection pressure of the molten alloy from the slit 7 be 2 kPa or more and less than 60 kPa. To more stably generate paddles, this ejection pressure is more preferably 10 kPa or more and less than 40 kPa, and even more preferably 10 kPa or more and less than 30 kPa. The ejection pressure can be adjusted by the head pressure and additional pressure in the molten metal storage container 5 shown in Figure 1.

[0054] The above description shows preferred equipment configurations and cooling conditions for manufacturing Fe-Si-B thick plate rapid solidification alloy strips with an average thickness of 30 μm or more and less than 70 μm, and an average width of 50 mm or more and less than 200 mm. This allows for obtaining rapid solidification alloy strips containing 90 volume% or more of amorphous alloy structure. In contrast, when manufacturing Fe-Si-B thick plate rapid solidification alloy strips with an average thickness of 30 μm or more and less than 70 μm, a single-slit nozzle with a single slit 7, as shown in Figure 5, is used as the molten metal outlet nozzle 6 of the single-roll molten metal rapid cooling apparatus 1 shown in Figure 1. The preferred conditions in this case, differing only from the above description, are as follows.

[0055] First, the diameter 2R of the cooling roll 8 is 500 mm or more and less than 2500 mm. Considering the homogeneity of the rapidly solidified alloy structure, 570 mm or more and less than 2500 mm is preferable, and considering the constraints on processing equipment and manufacturing costs of cooling rolls manufactured by forging methods, etc., 570 mm or more and less than 1500 mm is more preferable. That is, the curvature κ of the cooling roll 8 is 8 × 10 -4 The above 4 x 10 -3 It is less than 8 × 10 -4 The above 3.5 × 10 -3 Less than 1.3 × 10 is preferable. -3 The above 3.5 × 10 -3 Less than is preferable.

[0056] The cooling water volume is 0.05 m³. 3 If the cooling water volume falls below 0.3 m³ / min, it becomes difficult to complete the primary and secondary cooling on the surface of the cooling roll 8, while the cooling water volume is less than 0.3 m³ / min. 3 If the value exceeds / min, the paddles generated on the surface of the cooling roll 8 become unstable, therefore, 0.05 m 3 / min or more 0.3 m 3 Preferably less than / min, and 0.05 m 3 / min or more 0.2 m 3 Less than / min is preferable.

[0057] The width W2 of the slit 7 shown in Figure 5(a) is set to 0.5 mm or more and less than 1.5 mm. If the width is less than 0.5 mm, the flow of molten metal passing through the slit 7 is obstructed, increasing the likelihood of nozzle blockage. On the other hand, if the width is 1.5 mm or more, the rate of molten metal supplied to the cooling roll becomes too large, preventing sufficient cooling of the molten metal by the cooling roll, which may result in an inability to obtain the desired amorphous structure. Considering the machinability and accuracy of the slit, the width W2 of the slit 7 is more preferably 0.5 mm or more and less than 1.2 mm, and even more preferably 0.6 mm or more and less than 1.0 mm.

[0058] The length L2 of the slit 7 shown in Figure 5(b) can be appropriately selected depending on the width of the cooling roll and the required core size of the motor, etc., and is not necessarily limited. However, if the length is less than 4 mm, the application fields as a laminated core are limited, while if the length is 50 mm or more, the molten metal pouring rate supplied to the cooling roll 8 becomes too large, and the molten metal cannot be sufficiently cooled by the cooling roll 8, which may prevent the desired amorphous structure from being obtained. Therefore, the length L2 of the slit 7 is preferably 4 mm or more and less than 50 mm, and considering productivity including running costs and the cost of the single-roll molten metal rapid cooling device, it is more preferably 7 mm or more and less than 50 mm, and even more preferably 10 mm or more and less than 50 mm.

[0059] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0060] 200 kg of raw materials, each containing elements B, C, Si, Nb, Cu, and Fe with a purity of 99.5% or higher, were placed in an alumina crucible and melted by high-frequency induction heating to form molten alloy. 50 kg of this molten alloy was poured into an alumina storage container with an inner diameter of 200 mm and a height of 400 mm, which had a BN outlet nozzle with slits as shown in Table 1 at its bottom. After this, the 50 kg of molten alloy was further heated by energizing high-frequency heating coils installed around the storage container. Once the temperature of the molten alloy reached a temperature at least 50°C higher than the melting point of the alloy composition, an alumina molten metal stopper placed above the outlet nozzle was removed. This caused the molten alloy to be ejected from the outlet nozzle onto the surface of the cooling roll directly below. The size of the cooling roll and operating parameters are shown in Table 2. The average molten metal ejection rate is shown in Table 3.

[0061] The molten alloy that came into contact with the surface of the cooling roll formed paddles on the surface of the cooling roll, and rapidly solidified at the interface between the paddles and the cooling roll, thereby obtaining a thin strip of rapidly solidified alloy. The average thickness and width of this rapidly solidified alloy strip are shown in Table 3.

[0062] For the obtained rapidly solidified alloy strips, the X-ray diffraction patterns of the surface in contact with the cooling roll (roll surface) and the opposite surface not in contact with the cooling roll (free surface) were measured, and the microstructure was evaluated. The results are shown in Table 3 as the volume ratio of amorphous structures. As shown in Table 3, for Examples 1-12, it was confirmed that the structure consisted of an amorphous single-phase structure or an amorphous structure that dominated, with fine crystals, judged to be α-Fe, on the free surface side. Representative examples of the X-ray diffraction patterns on the roll surface and free surface of the rapidly solidified alloy strips for the examples are shown in Figure 7 for Example 2, Figure 8 for Example 5, and Figure 9 for Example 10.

[0063] On the other hand, for Comparative Examples 13-21, as shown in Table 3, the volume ratio of amorphous structure decreased compared to Examples 1-12 due to insufficient rapid cooling capacity. As representative examples of the X-ray diffraction patterns on the roll surface and free surface of the rapidly solidified alloy strips of the comparative examples, Comparative Example 13 is shown in Figure 10 and Comparative Example 17 is shown in Figure 11.

[0064] Comparative Example 13, shown in Figure 10, does not exhibit the halo pattern characteristic of an iron-based amorphous alloy centered around 45 degrees, which is seen in amorphous structures. Furthermore, both the rolled and free surfaces show peaks indicating very strong crystallinity in α-Fe(200), suggesting the presence of α-Fe crystals oriented in the in-plane direction of the rapidly solidified alloy strip. In contrast, Comparative Example 17, shown in Figure 11, shows strong α-Fe crystal peaks, indicating that an amorphous structure was not obtained.

[0065] Comparative Example 21, shown in Figure 12, shows the X-ray diffraction pattern of a rapidly solidified alloy strip prepared under the same conditions as Example 10, except for the cooling water temperature of the cooling roll. Poor adhesion between the cooling roll and the molten alloy during rapid cooling of the molten metal resulted in uneven cooling, which reduced the overall molten metal cooling rate. A peak indicating very strong crystallinity was observed in α-Fe (200) on the free face side.

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3] [Industrial applicability]

[0069] The Fe-Si-B thick plate rapid-solidification alloy strip obtained by the present invention can be suitably used as a low-iron-loss laminated core that is easily applicable to reactors, various motors, generators, and the like. Furthermore, it is possible to provide the market with an Fe-Si-B amorphous alloy that can be used for laminated cores, characterized by low iron loss and high magnetic permeability, on a mass production scale at a low cost, as an alternative to electrical steel sheets, which are widely used in various transformers and motors. [Explanation of Symbols]

[0070] 1. Single-roll molten metal rapid cooling device 2 Melting furnace 3. Molten alloy 4 Tilt axis 5. Hot water storage container 6. Hot water nozzle 7 slits 8 Cooling Rolls 9. Rapidly solidified alloy strip

Claims

1. A method for producing an alloy strip, comprising: spraying molten Fe-Si-B alloy, which requires iron (Fe), boron (B), and silicon (Si), from a pouring nozzle onto the surface of a cooling roll; rotating the cooling roll at a surface speed of 15 m / sec to 50 m / sec; and rapidly cooling the molten alloy on the surface of the cooling roll. The aforementioned hot water nozzle has slits with a width of 0.2 mm or more and less than 1.2 mm formed in two rows along the direction in which the alloy thin strip is formed. The cooling roll has a curvature of 9 × 10⁻⁴, Cooling water between 5°C and 60°C, 0.3 m 3 / min or more 20 m 3 A method for producing a rapidly solidified Fe-Si-B thick plate alloy strip, wherein the rapidly solidified alloy strip has an average thickness of 30 μm or more and less than 70 μm, an average width of 50 mm or more and less than 200 mm, and contains 90 volume percent or more of amorphous alloy structure, by passing cooling water through the cooling roll at a cooling water rate of less than / min.

2. Each of the slits in the hot water nozzle is the same length within the range of 45 mm to less than 200 mm, and the spacing between them is 0.5 mm to less than 5.0 mm. A method for producing a Fe-Si-B thick plate rapid solidification alloy thin strip according to claim 1, wherein the distance from the tip of the hot water nozzle to the surface of the cooling roll is 0.15 mm or more and less than 30 mm.

3. The method for producing a Fe-Si-B thick plate rapid solidification alloy thin strip according to claim 1, wherein the cooling roll is made of a material mainly composed of Cu, Mo, or W, has an arithmetic mean surface roughness Ra of 10 nm or more and less than 20 μm, is formed to be 50 mm or more and less than 400 mm longer than the length of the slit, and has a thickness from the surface to the cooling water channel of 5 mm or more and less than 50 mm.

4. A method for producing a Fe-Si-B thick plate rapid solidification alloy thin strip according to claim 1, wherein the ejection pressure of the molten alloy ejected from the slit is 2 kPa or more and less than 60 kPa.

5. The composition formula of the molten alloy is T loo-ｘ-ｙ-ｚ-ｎ Q ｘ Si y M n A method for producing a Fe-Si-B thick plate rapid solidification alloy thin strip according to claim 1, wherein the composition ratios x, y, and n satisfy 5 ≤ x < 20 atomic%, 2 ≤ y < 15 atomic%, 0 ≤ n < 10 atomic%, and the composition ratio C / (B+C) of Q is 0 or more and less than 0.2.

Images