Alloyed shot and method of making same

Abstract

The application provides an alloy rapid solidification piece and a preparation method thereof. The preparation method of the alloy rapid solidification piece comprises the following steps: pouring alloy liquid to the outer surface of a cooling roller, and forming the alloy rapid solidification piece after the alloy liquid is cooled; the outer surface of the cooling roller is provided with at least one first stripe and at least one second stripe; each first stripe and at least one second stripe are staggered to form staggered points; at the staggered points, the included angle between the tangent of the outer surface of the cooling roller and the central axis of the cooling roller is 40° to 50° for the first stripe, and the included angle between the tangent of the outer surface of the cooling roller and the central axis of the cooling roller is -50° to -40° for the second stripe. The application can increase the up-roller degree of the alloy liquid, thereby reducing the columnar crystal width in the alloy rapid solidification piece, increasing the nucleation number of the alloy microstructure, optimizing the structure of the alloy rapid solidification piece and improving the magnetic performance of the product.

Description

Technical Field

[0001] The invention provides an alloy quick-setting sheet and a preparation method thereof. Background Art

[0002] During the preparation of alloy quick-setting sheets, conventional techniques typically use cooling rollers to cool the alloy liquid, during which microstructure nucleation and growth occur. However, during this cooling process, the alloy liquid often struggles to be fed onto the rollers. This results in uneven cooling of the alloy liquid, unclear nucleation points, and difficulty in promoting microstructure nucleation and growth. Consequently, the resulting alloy quick-setting sheets fail to achieve the desired cooling effect. For example, it is difficult to reduce the size of columnar crystals in the alloy quick-setting sheets and improve their uniformity, thereby affecting their microstructure and magnetic properties.

[0003] Therefore, it is necessary to provide a better process to increase the rolling degree of the alloy liquid and increase the number of nucleations in the alloy microstructure, thereby reducing the width of the alloy microscopic columnar crystals and further improving the microstructure and magnetic properties of the alloy sheet. Summary of the Invention

[0004] In order to solve the defects in the prior art that the alloy liquid is not in sufficient contact with the cooling roller, the nucleation points produced are not obvious, and the alloy quick-setting sheet cannot achieve the ideal cooling effect, an alloy quick-setting sheet and a preparation method thereof are provided; the preparation method of the present invention can increase the upper roller degree of the alloy liquid, thereby reducing the width of the columnar crystals in the alloy quick-setting sheet, and can increase the number of nucleations in the alloy microstructure, optimize the organizational structure of the alloy quick-setting sheet and improve the magnetic properties of its product.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] The present invention provides a method for preparing an alloy rapid-setting sheet, which comprises the following steps: casting an alloy liquid onto the outer surface of a cooling roller, and forming an alloy rapid-setting sheet after the alloy liquid is cooled;

[0007] In which, the outer surface of the cooling roller is provided with at least one first stripe and at least one second stripe; each first stripe is staggered with at least one second stripe to form an intersection point; at the intersection point, the angle between the tangent of the first stripe along the outer surface of the cooling roller and the central axis of the cooling roller is 40° to 50°, and the angle between the tangent of the second stripe along the outer surface of the cooling roller and the central axis of the cooling roller is -50° to -40°.

[0008] In the present invention, a negative angle indicates that it is in the opposite direction to the corresponding positive angle. With the central axis of the cooling roller as the baseline, the angle between the tangent line of the first stripe along the outer surface of the cooling roller and the central axis of the cooling roller is counterclockwise, while the angle between the tangent line of the second stripe along the outer surface of the cooling roller and the central axis of the cooling roller is clockwise. Alternatively, with the central axis of the cooling roller as the baseline, the angle between the tangent line of the first stripe along the outer surface of the cooling roller and the central axis of the cooling roller is clockwise, while the angle between the tangent line of the second stripe along the outer surface of the cooling roller and the central axis of the cooling roller is counterclockwise.

[0009] In some embodiments, an angle between a tangent line of the first stripes along the outer surface of the cooling roller and the central axis of the cooling roller is 45°.

[0010] In some embodiments, the angle between a tangent line of the second stripes along the outer surface of the cooling roller and the central axis of the cooling roller is -45°.

[0011] In the present invention, the alloy liquid forms alloy rapid solidification sheets on the outer surface of the cooling roller, and the positions of the intersection points of the cooling roller correspond to nucleation points for generating alloy rapid solidification sheets.

[0012] In the present invention, the nucleation point of the alloy rapid solidification sheet belongs to the microstructure, and the dendrite structure of the alloy rapid solidification sheet will start to grow from the nucleation point.

[0013] In the present invention, the more nucleation points of the alloy rapid solidification sheet, the more dendrites of the alloy rapid solidification sheet, and the smaller the final columnar crystal width.

[0014] The number of nucleation points of the alloy quick-setting sheet is greater than or equal to 250 / mm 2 , for example 326 pieces / mm 2 .

[0015] In a preferred embodiment, the angle between the first stripes and the central axis of the cooling roller is 45°, and the angle between the second stripes and the central axis is -45°. If any first stripes and any second stripes are arranged according to this structure, the intersection points are most uniform. The alloy sheet produced from a cooling roller with this structure has finer and more uniformly grown dendrites.

[0016] In some embodiments, the surface roughness of the cooling roller is 3.0 μm to 5.0 μm, for example, 4.1 μm or 4.2 μm.

[0017] In some embodiments, the length of the cooling roller is 590 mm; and the length of the cooling roller is the length of the rectangle of the cooling roller when it is spread along the axial direction; and the length of the cooling roller is the width of the rectangle of the cooling roller when it is spread along the axial direction.

[0018] In some embodiments, the depth of the first stripe and the depth of the second stripe are each independently 0.005 mm to 0.05 mm, for example 0.01 mm.

[0019] In some embodiments, the number of the first stripes and the number of the second stripes are each greater than or equal to 10,000; preferably, the number of the first stripes and the number of the second stripes are each 12,700.

[0020] In some embodiments, the distance between two adjacent first stripes is equal.

[0021] In some embodiments, the distance between two adjacent second stripes is equal.

[0022] In some embodiments, the distance between two adjacent first stripes and the distance between two adjacent second stripes are each 0.01 mm to 0.05 mm; preferably, the distance between two adjacent first stripes and the distance between two adjacent second stripes are each 0.02 mm.

[0023] In some embodiments, the curvature of the first stripe and the curvature of the second stripe are each 2 m -1 -3 m -1 ; preferably, the curvature of the first stripe and the curvature of the second stripe are each 2.47 m -1 .

[0024] In some embodiments, the starting point of at least one first stripe is located at one end edge of the cooling roller, and the ending point of at least one first stripe is located at the other end edge of the cooling roller. In some preferred embodiments, the starting point of any first stripe is located at one end edge of the cooling roller, and the ending point of any first stripe is located at the other end edge of the cooling roller.

[0025] In some embodiments, the starting point of at least one second stripe is located at one end edge of the cooling roller, and the ending point of at least one second stripe is located at the other end edge of the cooling roller. In some preferred embodiments, the starting point of any second stripe is located at one end edge of the cooling roller, and the ending point of any second stripe is located at the other end edge of the cooling roller.

[0026] In the present invention, the distance from the starting point to the end point of the first stripe and the second stripe may be 800 mm; wherein, the distance from the starting point to the end point refers to the arc distance from one end point to the other end point of the stripe along the trajectory of the stripe on the outer surface of the cooling roller.

[0027] In some embodiments, the first stripes and the second stripes are respectively formed by grinding the outer surface of the cooling roller with sandpaper.

[0028] In a specific embodiment, during the grinding process, the linear speed of the cooling roller is 500-1100 mm / s, for example, 848 mm / s.

[0029] In a specific embodiment, during the grinding process, the grinding speed of the sandpaper is the same as or similar to the linear speed of the cooling roller; if the grinding speed of the sandpaper is significantly different from the linear speed of the cooling roller, it will affect the grinding efficiency of the cooling roller and the grinding effect, thereby affecting the rapid-setting sheet nucleation effect.

[0030] In one embodiment, during the grinding process, the linear speed of the cooling roller is 848 mm / s; and the grinding speed of the sandpaper is 20 rpm.

[0031] In a specific embodiment, the grinding method includes: when the cooling roller rotates forward, the sandpaper moves forward along the central axis of the cooling roller; when the cooling roller rotates backward, the sandpaper moves backward along the central axis of the cooling roller.

[0032] The forward rotation means that when the cooling roller is installed normally, the cooling roller rotates counterclockwise; the reverse rotation means that when the cooling roller is installed normally, the cooling roller rotates clockwise.

[0033] In some embodiments, the cooling roller comprises a metal roller, such as a copper roller.

[0034] In some embodiments, the cooling roller is a tubular structure with a hollow interior, and the internal channel of the cooling roller is used for the circulation of a cooling medium.

[0035] In some embodiments, the casting temperature is 1200-1600°C, for example 1430°C.

[0036] In some embodiments, during the casting process, the rotation speed of the cooling roller is 20 rpm-40 rpm, for example, 31 rpm.

[0037] In some embodiments, during the casting process, the casting flow rate of the alloy liquid is 0.5-2 kg / s, such as 0.9-1.1 kg / s.

[0038] In some embodiments, the alloy quick-setting sheet may be composed of conventional NdFeB or high-low heavy rare earth alloys in the art, but does not include a formula with a rhenium (RE) content greater than 40%.

[0039] In some embodiments, the elements in the alloy quick-setting sheet include PrNd, B, Fe, Cu, Dy, Ho, Nb, Al, Co, and Ca.

[0040] In a specific embodiment, the elements in the alloy quick-setting sheet include 27% PrNd, 0.98% B, 65.79% Fe, 0.2% Cu, 0.7% Dy, 3% Ho, 0.2% Nb, 0.5% Al, 1.5% Co and 0.13% Ca.

[0041] The present invention also provides an alloy rapid-setting sheet, which is prepared by the above-mentioned method for preparing the alloy rapid-setting sheet.

[0042] In the present invention, preferably, the width of the columnar crystals of the alloy rapid solidification sheet is 2.1-3.9 μm.

[0043] In some embodiments, the width of the columnar crystals of the alloy rapid solidification sheet is 2.1-3.5 μm, for example, 3.5 μm.

[0044] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0045] The reagents and raw materials used in the present invention are commercially available.

[0046] The positive progress effect of the present invention is:

[0047] The preparation method of the present invention can increase the upper rolling degree of the alloy liquid, thereby reducing the width of the columnar crystals in the alloy rapid solidification sheet, and can increase the number of nucleations in the alloy microstructure, optimize the organizational structure of the alloy rapid solidification sheet and improve the magnetic properties of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a characterization diagram of the results of the alloy rapid solidification sheet of Example 1 of the present application.

[0049] Figure 2 This is a characterization diagram of the results of the alloy rapid solidification sheet of Comparative Example 1.

[0050] Figure 3 This is a schematic structural diagram of the cooling roller of Example 1 of the present application unfolded along the axial direction.

[0051] Description of reference numerals:

[0052] Cooling roller 1

[0053] First Stripe 101

[0054] Second Stripe 102

[0055] Intersection 103

[0056] Bearing 2. DETAILED DESCRIPTION

[0057] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0058] Example 1

[0059] The components for preparing the alloy quick-setting sheet in this embodiment include 27% PrNd, 0.98% B, 65.79% Fe, 0.2% Cu, 0.7% Dy, 3% Ho, 0.2% Nb, 0.5% Al, 1.5% Co and 0.13% Ca.

[0060] This embodiment is a method for preparing an alloy quick-setting sheet, which adopts a device for preparing an alloy quick-setting sheet (including existing conventional components such as a smelting furnace and a cooling device), and includes the following steps: casting the alloy liquid onto the outer surface of the cooling roller 1, and forming an alloy quick-setting sheet after the alloy liquid is cooled.

[0061] The casting temperature is 1430° C.; during the casting process, the rotation speed of the cooling roller is 31 rpm, and the casting flow rate of the alloy liquid is 0.9-1.1 kg / s.

[0062] Among them, the cooling roller in the preparation device of the alloy quick-setting sheet has the following design: the outer surface of the cooling roller 1 is provided with 12,700 first stripes 101 and 12,700 second stripes 102; with the central axis of the cooling roller as the reference, the angle between the first stripe 101 and the central axis is 45°, and the angle between the second stripe 102 and the central axis is -45°, so that each first stripe 101 and each second stripe 102 are staggered; during the casting process of the alloy liquid, each staggered point 103 is the nucleation point of the alloy; the cooling roller 1 is fixed by the bearing 2; the length of the cooling roller 1 is 590 mm; the end face circumference of the cooling roller 1 is 2543 mm; wherein, the length and end face circumference of the cooling roller 1 respectively refer to the length and width of the rectangle expanded along the axial direction of the cooling roller 1. Figure 3 This is a schematic structural diagram of the cooling roller of this embodiment unfolded along the axial direction.

[0063] Among them, the number of nucleation points on the alloy rapid solidification sheet after casting is 326 / mm 2The surface roughness of the cooling roller 1 is 4.2 μm. The depth of the first stripe 101 and the depth of the second stripe 102 are both 0.01 mm. The spacing between two adjacent first stripes 101 and the spacing between two adjacent second stripes 102 are both 0.02 mm. The curvature of the first stripe 101 and the second stripe 102 are both 2.47 mm. -1 ; The starting point of each first stripe is located at one end edge of the cooling roller, and the end point of each first stripe is located at the other end edge of the cooling roller; the starting point of each second stripe is located at one end edge of the cooling roller, and the end point of each second stripe is located at the other end edge of the cooling roller; the distance between the first stripe and the second stripe from the starting point to the end point is 800 mm.

[0064] The first and second stripes are respectively polished on the outer surface of the cooling roller using sandpaper; the polishing speed of the sandpaper is the same as the rotational speed of the cooling roller, the linear speed of the cooling roller is 848 mm / s, and the polishing speed of the sandpaper is 20 rpm; the polishing method includes: when the cooling roller rotates forward, the sandpaper moves forward along the central axis of the cooling roller, and forward rotation means that when the cooling roller is normally installed, the cooling roller rotates counterclockwise; the cooling roller is a copper roller; the cooling roller has an internal hollow tubular structure, and the internal channel of the cooling roller is used for the circulation of the cooling medium.

[0065] Comparative Example 1

[0066] This comparative example is a method for preparing an alloy quick-setting sheet, which includes the following steps: casting the alloy liquid onto the outer surface of a cooling roller, and forming an alloy quick-setting sheet after the alloy liquid is cooled; the cooling roller has not been polished and does not contain stripes, and other conditions are the same as those in Example 1.

[0067] Effect Example 1

[0068] The characterization experiments of Example 1 and Comparative Example 1 were carried out respectively by conventional detection methods in the field. The microscopic detection method mainly includes: ① sampling of alloy quick-setting sheet; ② metallographic mounting; ③ polishing; ④ polishing; ⑤ microscopic detection using scanning electron microscope S-3400N (Hitachi manufacturer), and the obtained Figure 1 and Figure 2 . Figure 1 This is a characterization diagram of the results of the alloy rapid solidification sheet of Example 1; Figure 2 The results of the alloy rapid-setting sheet of Comparative Example 1 are characterized in Figure 1. The performance parameters of the alloy rapid-setting sheets of Example 1 and Comparative Example 1 were obtained through analysis, as shown in Table 1. Magnets were then fabricated from the two alloy rapid-setting sheets according to conventional methods in the art. These magnets were cut into cylindrical shapes with a diameter of 10 mm and a height of 10 mm. The residual magnetization and intrinsic coercivity of the two magnets were tested using a NIM direct current magnetic field.

[0069] Table 1

[0070]

[0071] Table 1 is a comparison of the performance parameters of the alloy rapid solidification sheet and its magnet of Example 1 and Comparative Example 1. As shown in Table 1, the number of nucleation points of the alloy rapid solidification sheet prepared in Example 1 is 326 / mm 2 , much larger than the alloy sheet prepared in Comparative Example 1. Furthermore, the dendrites of the alloy sheet prepared in Example 1 are small and evenly distributed, with a columnar crystal width of 3.5 μm, while the dendrites of the alloy sheet prepared in Comparative Example 1 are coarse, with a columnar crystal width of 5.2 μm. Magnets made from the alloy sheet prepared in Example 1 have a higher intrinsic coercivity.

Claims

1. A method for preparing an alloy quick-setting sheet, characterized in that: The method comprises the following steps: casting the alloy liquid onto the outer surface of the cooling roller, and forming the alloy quick-setting sheet after the alloy liquid is cooled; The outer surface of the cooling roller is provided with at least one first stripe and at least one second stripe; each first stripe is staggered with at least one second stripe to form an intersection point; at the intersection point, the angle between the tangent line of the first stripe along the outer surface of the cooling roller and the central axis of the cooling roller is 40° to 50°, and the angle between the tangent line of the second stripe along the outer surface of the cooling roller and the central axis of the cooling roller is -50° to -40°; The depth of the first stripes and the depth of the second stripes are each independently 0.005 mm to 0.05 mm; The distance between two adjacent first stripes and the distance between two adjacent second stripes are both 0.01 mm to 0.05 mm; The curvature of the first stripe and the second stripe are both 2m -1 -3m -1 .

2. The method for preparing the alloy quick-setting sheet according to claim 1, wherein: The angle between the tangent line of the first stripe along the outer surface of the cooling roller and the central axis of the cooling roller is 45°; and / or, the angle between the tangent line of the second stripe along the outer surface of the cooling roller and the central axis of the cooling roller is -45°; And / or, the number of nucleation points of the alloy rapid solidification sheet is greater than or equal to 250 / mm 2 .

3. The method for preparing the alloy quick-setting sheet according to claim 1, wherein: The surface roughness of the cooling roller is 3.0 μm to 5.0 μm; and / or, the number of the first stripes and the number of the second stripes are both greater than or equal to 10,000; and / or, the distances between two adjacent first stripes are equal; And / or, the distance between two adjacent second stripes is equal.

4. The method for preparing the alloy quick-setting sheet according to claim 1, wherein: The first stripes and the second stripes are respectively formed by grinding the outer surface of the cooling roller with sandpaper.

5. The method for preparing the alloy quick-setting sheet according to claim 4, wherein: During the grinding process, the linear speed of the cooling roller is 500-1100 mm / s; And / or, during the grinding process, the grinding speed of the sandpaper is the same as the linear speed of the cooling roller.

6. The method for preparing the alloy rapid solidification sheet according to claim 4, wherein: The grinding method includes: when the cooling roller rotates forward, the sandpaper moves forward along the central axis of the cooling roller; when the cooling roller rotates backward, the sandpaper moves backward along the central axis of the cooling roller.

7. The method for preparing the alloy rapid-setting sheet according to claim 1, wherein: The cooling roller comprises a metal roller; And / or, the cooling roller is a tubular structure with a hollow interior, and the internal channel of the cooling roller is used for the circulation of the cooling medium; And / or, the casting temperature is 1200-1600°C; and / or, during the casting process, the rotation speed of the cooling roller is 20 rpm-40 rpm; And / or, during the casting process, the casting flow rate of the alloy liquid is 0.5-2 kg / s.

8. The method for preparing the alloy quick-setting sheet according to claim 1, wherein: The elements in the alloy quick-setting sheet include PrNd, B, Fe, Cu, Dy, Ho, Nb, Al, Co and Ca.

9. An alloy quick-setting sheet, characterized in that: The alloy quick-setting sheet is prepared by the preparation method of the alloy quick-setting sheet according to any one of claims 1 to 8.

10. The alloy quick-setting sheet according to claim 9, characterized in that: The width of the columnar crystals of the alloy quick-setting sheet is 2.1-3.9 μm.

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