A method for preparing a tubular target material

Abstract

The present application relates to the technical field of target material preparation, and provides a method for preparing a tubular target material, the method comprising the following steps: obtaining molten metal; introducing the molten metal into a centrifugal casting mold with a hollow cylindrical structure through a casting port, during the casting process, the casting port remains fixed in position, the centrifugal casting mold rotates around its central axis while displacing axially, the molten metal cast by the casting port forms a casting tube section under the action of centrifugal force, and during the formation of the casting tube section, the molten metal exceeding the preset thickness on the newly formed casting tube section is continuously scraped off; cooling, demolding to obtain a tubular target material. The preparation method provided by the present application continuously scrapes off the molten metal exceeding the preset thickness on the newly formed casting tube section while casting, which can ensure the thickness consistency of each position of the cast tubular target material.

Description

Technical Field

[0001] The present application belongs to the technical field of target material preparation, and in particular, relates to a method for preparing a tubular target material. Background Art

[0002] Neodymium iron boron (NdFeB) rare earth permanent magnets are an important component of new energy vehicle motors. In order to improve the application performance of neodymium iron boron (NdFeB) rare earth permanent magnets in motors, an existing process is to deposit rare earth elements terbium and / or dysprosium on the surface of neodymium iron boron (NdFeB) rare earth permanent magnet materials through magnetron sputtering, and then diffuse into the interior of the magnet through grain boundaries, which can significantly improve the coercive force of the magnet.

[0003] In order to reduce the consumption of heavy rare earth metals terbium and dysprosium and improve the efficiency of target materials, the target materials used in the magnetron sputtering coating process have evolved from planar targets to rotating targets. This not only reduces the production cost of permanent magnet materials, but also improves the resource utilization rate of the industry.

[0004] The main preparation methods of rotary targets include melt casting, powder metallurgy and rotary spraying. Powder metallurgy and rotary spraying usually use rare earth metal powder as raw materials. During operation, due to the high activity of rare earth metals, the powder is easily oxidized and even causes combustion. Therefore, there are great risks in the preparation process. In addition, the overall density of the tubular target prepared is low and contains many pores inside, which will affect the subsequent coating quality.

[0005] In contrast, the melting and casting method uses metal blocks as raw materials and operates in a vacuum or inert gas protection environment. This method is not only safer, but also has a lower oxygen content in the finished product, so it has become the main method for preparing rotating targets. However, the melting and casting method is limited by the size of the melting furnace and the difficulty of mold demolding. The existing casting molds are difficult to meet the casting requirements of longer tubular targets. At present, most of them first cast multiple short sections of rare earth tubular targets, and then use the method of splicing short sections of rare earth tubular targets to obtain longer tubular targets. However, this method is prone to uneven sputtering at the splicing process during sputtering coating.

[0006] There is a centrifugal casting method for preparing tubular metals. However, when this method is used in the manufacture of rare earth metal targets, the thickness uniformity of the tubular targets obtained by casting is poor, and a large amount of subsequent machining is required, resulting in material waste and low production efficiency. Summary of the invention

[0007] The purpose of the present application is to provide a method for preparing a tubular target material, aiming to solve the problem that the existing preparation of tubular targets has poor thickness uniformity and requires a lot of machining.

[0008] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0009] In a first aspect, the present application provides a method for preparing a tubular target, comprising the following steps:

[0010] Obtaining molten metal;

[0011] The molten metal is introduced into a centrifugal casting mold with a hollow cylindrical structure through a casting port. During the casting process, the casting port is kept in a fixed position, and the centrifugal casting mold is rotated around its central axis while being displaced axially. The molten metal cast from the casting port forms a casting pipe section under the action of centrifugal force. During the formation of the casting pipe section, the molten metal exceeding a preset thickness on the newly formed casting pipe section is continuously scraped off;

[0012] After cooling, demoulding and obtaining a tubular target material.

[0013] Optionally, when performing a scraping operation on the molten metal, a force is applied to the scraped molten metal toward the casting port to push the scraped molten metal toward the casting port.

[0014] Optionally, a baffle is arranged above the bottom wall of the inner cavity of the centrifugal casting mold, and the baffle and the casting port are arranged at intervals along the axial direction of the centrifugal casting mold. During the casting process, the centrifugal casting mold is displaced in the direction from the casting port to the baffle, and the casting port and the baffle remain in fixed positions. The baffle is used to scrape off the molten metal that exceeds a preset thickness on the newly formed casting pipe section.

[0015] Optionally, the baffle extends axially along the centrifugal casting mold, and is inclined toward the rotation direction of the bottom wall of the centrifugal casting mold along the direction from the baffle to the casting port, and the axial angle between the baffle and the centrifugal casting mold is 30°~60°, so that during the displacement of the centrifugal casting mold, the baffle applies a force toward the casting port to the scraped molten metal, thereby pushing the scraped molten metal toward one side of the casting port.

[0016] Optionally, during the casting process, the rotation speed of the centrifugal casting mold is 700-1000 rps, and the speed of axial displacement is 1-5 cm / s.

[0017] Optionally, during the casting process, the molten metal is guided to the casting port through a casting runner, and the casting runner is subjected to insulation and heating treatment, and the temperature of the molten metal in the casting runner is maintained at 700-1100°C.

[0018] Optionally, during the cooling process, the rotation speed of the centrifugal casting mold is reduced to 300-500 rps, and the rotation is kept for 10-20 minutes before stopping, and the mold is demolded after continuous cooling.

[0019] Optionally, the step of obtaining the molten metal includes:

[0020] The metal raw materials are melted and mixed, and the melting process is carried out in a vacuum or protective gas to obtain a molten metal.

[0021] Optionally, the molten metal includes rare earth metals and optionally transition metals, the rare earth metals include at least one of terbium, dysprosium and praseodymium, and the transition metals include at least one of aluminum and copper. Based on the total mass of the molten metal as 100%, the mass percentage of the rare earth metal is 60%~100%, and the mass percentage of the transition metal is 0~40%.

[0022] In a second aspect, the present application provides a rare earth permanent magnet, comprising a NdFeB magnet and a rare earth metal layer arranged on the surface of the NdFeB magnet, wherein the rare earth metal layer is obtained by sputtering a tubular target, and the tubular target is selected from the tubular target prepared by the preparation method described above.

[0023] In a second aspect, the present application provides a new energy vehicle, including a motor, wherein the motor includes the rare earth permanent magnet as described above.

[0024] Compared with the prior art, this application has the following beneficial effects:

[0025] The first aspect of the present application provides a method for preparing a tubular target material. During the casting process, molten metal is introduced into a centrifugal casting mold through a casting port. The centrifugal casting mold rotates to distribute the molten metal on the inner wall of the centrifugal casting mold through centrifugal force to form a casting tube section. This centrifugal casting method is beneficial to reducing the pores and oxygen content in the tubular target material obtained by casting. During casting, the centrifugal casting mold is axially displaced to increase the length of the casting tube section. The increase in the length of the casting tube section will increase the difficulty of controlling its thickness uniformity to a certain extent. In order to improve the thickness uniformity of the tubular target material obtained by casting, the present application continuously scrapes away the molten metal that exceeds a preset thickness on the newly formed casting tube section during the formation of the casting tube section to control the thickness of the cast tubular target material. As the centrifugal casting mold is axially displaced, the thickness consistency of each position of the cast tubular target material can be ensured.

[0026] The rare earth permanent magnet provided in the second aspect of the present application adopts the preparation method as described above to obtain a sputtered rare earth metal layer of a tubular target on the surface of a neodymium iron boron magnet. Since the tubular target has a low oxygen content and a high thickness uniformity, it is beneficial to improve the quality of the rare earth metal layer on the neodymium iron boron magnet, thereby facilitating more rare earth metals to diffuse evenly into the interior of the neodymium iron boron magnet, thereby improving the coercive force of the rare earth permanent magnet and ensuring its magnetic stability.

[0027] The new energy vehicle provided in the third aspect of the present application, whose motor includes the rare earth permanent magnet as described above, can maintain higher output power and efficiency and has better power performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 It is a structural schematic diagram of a centrifugal casting device provided in one embodiment of the present application;

[0030] Figure 2 It is a top view schematic diagram of the relative positions of the centrifugal casting mold and the baffle provided in one embodiment of the present application.

[0031] Among them, the reference numerals in the figure are:

[0032] 1—centrifugal casting mold; 11, inner cavity bottom wall; 2—casting flow channel; 21—casting port; 3—baffle; 31—baffle bracket; 4—funnel; 5—intermediate frequency furnace; 6—melting chamber; 7—track; 8—roller; 9, casting chamber. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] In the present application, "at least one" means one or more, and "more than one" means two or more.

[0035] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0036] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0037] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also indicate the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as µg, mg, g, kg, etc.

[0038] A first aspect of an embodiment of the present application provides a method for preparing a tubular target, comprising the following steps:

[0039] S1: Obtaining molten metal;

[0040] S2: introducing the molten metal into a centrifugal casting mold with a hollow cylindrical structure through a casting port. During the casting process, the casting port is kept in a fixed position, and the centrifugal casting mold is rotated around its central axis while displacing along the axial direction. The molten metal cast from the casting port forms a casting pipe segment under the action of centrifugal force. During the formation of the casting pipe segment, the molten metal exceeding a preset thickness on the newly formed casting pipe segment is continuously scraped off;

[0041] S3: Cooling and demolding to obtain a tubular target.

[0042] During the casting process, molten metal is introduced into the centrifugal casting mold through the casting port, and the centrifugal casting mold rotates to distribute the molten metal on the inner wall of the centrifugal casting mold through centrifugal force to form a casting tube segment. This centrifugal casting method is beneficial to reducing the pores and oxygen content in the tubular target material obtained by casting; while casting, the centrifugal casting mold is axially displaced, thereby increasing the length of the casting tube segment, and the increase in the length of the casting tube segment will increase the difficulty of controlling its thickness uniformity to a certain extent. In order to improve the thickness uniformity of the tubular target material obtained by casting, the present application continuously scrapes the molten metal that exceeds the preset thickness on the newly formed casting tube segment during the formation of the casting tube segment to control the thickness of the cast tubular target material, and with the axial displacement of the centrifugal casting mold, the thickness consistency of each position of the cast tubular target material can be ensured.

[0043] In the embodiment, in step S2, when the scraping operation of the molten metal is performed, a force is applied to the scraped molten metal toward the casting port, so that the scraped molten metal is pushed toward the casting port.

[0044] During the casting process, the centrifugal casting mold undergoes axial displacement. During the axial displacement of the centrifugal casting mold, a casting pipe section will be formed on the side of the casting port facing the baffle, and the thickness of the casting pipe section will be made consistent through scraping operation. In this embodiment, the scraping operation is continuously performed during the casting process. In order to prevent the scraped molten metal from entering the casting pipe section that has undergone the scraping operation and affecting the thickness uniformity, during the scraping operation, the scraped molten metal is applied with a force toward the casting port to push the scraped molten metal toward the casting port, which is beneficial to ensure the flatness of the casting pipe section that has undergone the scraping operation during the axial displacement of the centrifugal casting mold, and is beneficial to improve the overall thickness consistency of the tubular target material obtained by casting.

[0045] In the embodiment, in step S2, a baffle is arranged above the bottom wall of the inner cavity of the centrifugal casting mold, and the baffle and the casting port are arranged at intervals along the axial direction of the centrifugal casting mold. During the casting process, the centrifugal casting mold is displaced from the casting port to the baffle, and the casting port and the baffle are kept in fixed positions. The baffle is used to scrape off the molten metal that exceeds the preset thickness on the newly formed casting pipe section.

[0046] A baffle and a casting port are arranged at axial intervals of the centrifugal casting mold, and the casting port and the baffle are kept in fixed positions. During the axial displacement of the centrifugal casting mold, the metal melt is scraped off by the baffle. Specifically, during the axial displacement of the centrifugal casting mold, the distance between the baffle and the bottom wall of the inner cavity of the centrifugal casting mold remains unchanged, thereby ensuring the thickness consistency of different positions of the casting pipe section.

[0047] In an embodiment, the height of the baffle can be adjusted up and down, and the distance between the baffle and the bottom wall of the inner cavity of the centrifugal casting mold can be controlled by adjusting the height of the baffle to adjust the preset thickness of the casting pipe section.

[0048] In an embodiment, the baffle extends along the axial direction of the centrifugal casting mold, and is inclined toward the rotation direction of the bottom wall of the centrifugal casting mold along the direction from the baffle to the casting port. The axial angle between the baffle and the centrifugal casting mold is 30°~60°, so that during the displacement of the centrifugal casting mold, the baffle applies a force toward the casting port to the scraped molten metal, thereby pushing the scraped molten metal toward one side of the casting port.

[0049] The orientation of the baffle plate can, on the one hand, provide a scraping effect on the molten metal that exceeds a preset height during the centrifugation process, and on the other hand, prevent the scraped molten metal from entering the scraped casting pipe section.

[0050] In the embodiment, in step S2, during the casting process, the rotation speed of the centrifugal casting mold is 700-1000 rps, and the speed of axial displacement is 1-5 cm / s.

[0051] The rotation speed of the centrifugal casting mold is related to the molding quality of the tubular target. If the rotation speed of the centrifugal casting mold is too low, it is difficult to provide sufficient centrifugal force to achieve uniform distribution of the molten metal on the inner wall of the centrifugal casting mold, which is not conducive to the discharge of bubbles in the molten metal, especially when the centrifugal force is difficult to overcome the influence of gravity, the tubular target will not be able to be formed; if the rotation speed of the centrifugal casting mold is too high, the relative speed between the molten metal falling at the casting mouth and the centrifugal casting mold is too large, which can easily cause the molten metal to splash.

[0052] The speed of axial displacement of the centrifugal casting mold determines the extension speed of the casting pipe section. If the speed of axial displacement of the centrifugal casting mold is too fast, the cast metal melt will not be distributed on the inner wall of the centrifugal casting mold in time, and there is a problem that the thickness does not reach the preset thickness; if the speed of axial displacement of the centrifugal casting mold is too slow, the cast metal melt will accumulate, increasing the difficulty of thickness control.

[0053] In the embodiment, in step S2, during the casting process, the molten metal is guided to the casting port through the casting runner, and the casting runner is subjected to insulation and heating treatment, and the temperature of the molten metal in the casting runner is maintained at 700-1100°C.

[0054] By performing insulation treatment on the casting runner, the cooling rate of the molten metal in the casting runner during the casting process can be reduced; at the same time, heating treatment is performed to provide additional heat supplement, thereby ensuring the temperature of the molten metal in the casting runner, avoiding the problem of solidification of the molten metal in the casting runner causing blockage and reducing the casting flow rate, which is beneficial to ensure the consistency of the molten metal flow rate during the casting process and improve the uniformity of the thickness of the tubular target.

[0055] In an embodiment, the heating process is performed by electrical heating.

[0056] In the embodiment, in step S3, during the cooling process, the rotation speed of the centrifugal casting mold is reduced to 300-500 rps, and the rotation is kept for 10-20 minutes before stopping, and the mold is demolded after continuous cooling.

[0057] During the cooling process, the casting tube section in the centrifugal casting mold is not completely solidified. In the initial cooling stage, a certain rotation speed needs to be maintained to provide centrifugal force to maintain the stability of the casting tube section in the centrifugal casting mold. The demoulding operation can only be performed after the casting tube section is completely solidified to obtain a tubular target material. If the rotation speed of the centrifugal casting mold is too low, the casting tube section is prone to deformation; if the rotation speed of the centrifugal casting mold is too high, there is a problem of high energy consumption.

[0058] In an embodiment, in step S1, the step of obtaining molten metal includes:

[0059] The metal raw materials are melted and mixed, and the melting process is carried out in a vacuum or protective gas to obtain a molten metal.

[0060] The protective gas can be selected from gases that do not react with the molten metal, such as argon. The vacuum or protective gas can prevent the metal raw material or the molten metal from reacting with oxygen and water vapor in the air during the smelting process, thereby preventing the quality of the cast tubular target from being affected.

[0061] The metal raw material may be a single metal or an alloy.

[0062] In an embodiment, in step S1, the molten metal includes rare earth metals and optionally transition metals, the rare earth metals include at least one of terbium, dysprosium, and praseodymium, the transition metals include at least one of aluminum and copper, and based on the total mass of the molten metal as 100%, the mass percentage of the rare earth metal is 60% to 100%, and the mass percentage of the transition metal is 0 to 40%.

[0063] In some embodiments, the rare earth metal includes at least one of terbium and dysprosium, and optionally includes praseodymium.

[0064] When used as a sputtering target on the surface of a rare earth permanent magnet material, the rare earth metal can diffuse into the interior of the magnet to increase the coercive force of the magnet. Adding transition metals therein can help reduce the amount of rare earth metal used and improve utilization efficiency.

[0065] In the embodiment, in step S3, after demoulding, the obtained tubular target material is machined.

[0066] The machining process includes one or more of cutting, grinding and drilling.

[0067] A second aspect of an embodiment of the present application provides application of a tubular target material prepared by the preparation method described above as a rotating target material for sputtering.

[0068] Since the tubular target material is prepared by the preparation method as described above, the obtained tubular target material has high thickness uniformity, which reduces the subsequent machining amount and simplifies the processing flow. When it is used as a rotating target material for sputtering, it is beneficial to improve the uniformity of sputtering thickness at each position.

[0069] The rare earth permanent magnet provided in the third aspect of the embodiment of the present application is prepared by the preparation method as described above to obtain a sputtered rare earth metal layer of a tubular target on the surface of a neodymium iron boron magnet. Since the tubular target has a low oxygen content and a high thickness uniformity, it is beneficial to improve the quality of the rare earth metal layer on the neodymium iron boron magnet, thereby facilitating more rare earth metals to diffuse evenly into the interior of the neodymium iron boron magnet, thereby improving the coercive force of the rare earth permanent magnet and ensuring its magnetic stability.

[0070] The new energy vehicle provided in the fourth aspect of the embodiment of the present application, whose motor includes the rare earth permanent magnet as described above, can maintain higher output power and efficiency and has better power performance.

[0071] See also Figure 1 As shown, the fifth aspect of the embodiment of the present application provides a centrifugal casting device applied to the preparation method as described above, including a casting channel 2, a rotating mechanism, a centrifugal casting mold 1 and a baffle 3, the centrifugal casting mold 1 is a hollow cylindrical structure, the rotating mechanism is used to drive the centrifugal casting mold 1 to rotate, the casting channel 2 is provided with a casting port 21, the casting port 21 and the baffle 3 are spaced apart inside the centrifugal casting mold 1, and the baffle 3 is spaced apart from the inner wall of the centrifugal casting mold 1; the centrifugal casting mold 1 can be relatively displaced along the axial direction of the centrifugal casting mold 1 relative to the casting port 21 and the baffle 3.

[0072] In the centrifugal casting device, the casting channel 2, the centrifugal casting mold 1 and the baffle 3 are independent structures and do not interfere with each other during movement. During centrifugal casting, the centrifugal casting mold 1 is moved so that the casting port 21 of the casting channel 2 extends into the centrifugal casting mold 1, and the molten metal is introduced into the centrifugal casting mold 1 through the casting port 21. The rotating mechanism drives the centrifugal casting mold 1 to rotate, and the molten metal is distributed on the inner wall of the centrifugal casting mold 1 through centrifugal force, which is beneficial to reduce the pores and oxygen content in the tubular target material obtained by casting; while casting, the centrifugal casting mold 1 is axially displaced in a direction away from the casting channel 2, thereby realizing the casting of the tubular target. The length of the target material increases, and the increase in the length of the tubular target material will increase the difficulty of controlling its thickness uniformity to a certain extent. In order to improve the thickness uniformity of the tubular target material obtained by casting, the present application further provides a baffle 3 in the centrifugal casting mold 1, and the baffle 3 is spaced apart from the inner wall of the centrifugal casting mold 1. When the centrifugal casting mold 1 rotates, the relative movement of the baffle 3 and the centrifugal casting mold 1 will have a scraping effect on the molten metal on the inner wall of the centrifugal casting mold 1 to control the thickness of the cast tubular target material, and with the axial displacement of the centrifugal casting mold 1, the thickness consistency of each position of the cast tubular target material can be ensured, thereby improving the uniformity of the tubular target material as a rotating target material for magnetron sputtering.

[0073] In different embodiments, the relative displacement between the centrifugal casting mold 1 and the casting port 21 and the baffle 3 can be method 1: the casting port 21 and the baffle 3 remain fixed, and the centrifugal casting mold 1 is movably arranged; or method 2: the centrifugal casting mold 1 remains fixed, and the casting port 21 and the baffle 3 are movably arranged.

[0074] Compared with the second method, the first method only needs to consider the movement of the centrifugal casting mold 1, and the setting difficulty is lower.

[0075] In an embodiment, the centrifugal casting device also includes a track 7, which extends in a horizontal direction. The rotating mechanism can be horizontally displaced on the track 7. The centrifugal casting mold 1 is located on the rotating mechanism, and the axial direction of the centrifugal casting mold 1 is parallel to the track 7, that is, the axial direction of the centrifugal casting mold 1 is horizontally oriented.

[0076] Compared with other displacement methods, the method of setting the track 7 is conducive to ensuring the stability and guiding accuracy of the movement of the centrifugal casting mold 1, avoiding the centrifugal casting mold 1 from deviating from its axial direction during the movement, and is conducive to the stable control of its movement speed, thereby improving the uniformity of the casting amount at different positions in the centrifugal casting mold 1.

[0077] In an embodiment, the rotating mechanism includes a horizontal walking mechanism (not shown), a roller 8 and a motor (not shown). The horizontal walking mechanism can be horizontally displaced on the track 7, the motor and the roller 8 are arranged on the horizontal walking mechanism, the motor is used to drive the roller 8 to rotate, and the outer wall of the centrifugal casting mold 1 abuts against the roller 8.

[0078] The roller 8 is driven to rotate by a motor. The rotation of the roller 8 drives the centrifugal casting mold 1 to rotate through the friction between the roller 8 and the centrifugal casting mold 1, which can achieve a higher rotation rate and ensure the stability of the centrifugal casting mold 1 during the rotation process.

[0079] There are multiple rollers 8, and the multiple rollers 8 are spaced apart on both sides of the centrifugal casting mold 1 to provide sufficient friction to drive the centrifugal casting mold 1. A transmission mechanism is arranged between the motor and the single or multiple rollers 8. The transmission mechanism is not particularly limited and can adopt existing transmission structures such as gears, rotating shafts, chains, worm gears, etc.

[0080] There is no special restriction on the structure of the horizontal walking mechanism. It is sufficient to select an existing structure that can drive the rotating mechanism to move along the track 7. In one embodiment, the horizontal walking mechanism is a walking trolley, and a driving device is provided to drive the walking trolley to move along the track 7; in another embodiment, the horizontal walking mechanism includes a driving device, a gear and a rack, the rack is provided on the track 7, the gear is meshed with the rack, the driving device is connected to the gear to drive the rotation of the gear, and the rotating mechanism is driven to move along the track 7 through the cooperation of the gear and the rack.

[0081] In an embodiment, the centrifugal casting device also includes a baffle bracket 31, and the first opening and the second opening are respectively provided at both ends of the centrifugal casting mold 1, the casting channel 2 extends from the first opening into the centrifugal casting mold 1, and the baffle bracket 31 extends from the second opening into the centrifugal casting mold 1 and is connected to the baffle 3.

[0082] Since the baffle 3 and the centrifugal casting mold 1 can be relatively displaced, and the baffle 3 is located inside the centrifugal casting mold 1, it is necessary to set a baffle bracket 31 to support the baffle 3. One end of the baffle bracket 31 is connected to the baffle 3, and the other end of the baffle bracket 31 extends out of the centrifugal casting mold 1 and is connected and fixed to an external structure. The external structure is a structure that has no fixed relationship with the centrifugal casting mold 1 to ensure the relative displacement of the baffle 3 and the centrifugal casting mold 1.

[0083] In the embodiment, a first cover plate and a second cover plate are respectively provided at both ends of the centrifugal casting mold 1, and the first cover plate and the second cover plate are used to act as a stopper to prevent the molten metal from flowing out of the centrifugal casting mold 1. In order to allow the casting runner 2 and the baffle bracket 31 to extend into the centrifugal casting mold 1, the first opening is provided on the first cover plate, and the second opening is provided on the second cover plate.

[0084] In an embodiment, the centrifugal casting mold 1 comprises an inner cylinder and an outer cylinder, the inner cylinder is cast iron or graphite, and the outer cylinder is selected from iron and its alloys.

[0085] Cast iron or graphite is used as the inner cylinder of the centrifugal casting mold 1. The material is relatively stable and can withstand the high temperature of the molten metal. At the same time, it has self-lubricating properties and can reduce the demoulding difficulty of the cast tubular target.

[0086] In an embodiment, the centrifugal casting device further comprises a baffle adjusting device, and the baffle adjusting device is used to adjust the distance between the baffle 3 and the inner wall of the centrifugal casting mold 1 .

[0087] In the present centrifugal casting device, the function of the baffle 3 is to maintain the consistency of the thickness of the molten metal at each position in the axial direction by scraping off the excess molten metal on the inner wall during the centrifugal casting process. Therefore, by adjusting the distance between the baffle 3 and the inner wall of the centrifugal casting mold 1 through the baffle adjustment device, the thickness of the molten metal can be adjusted, so that it has better thickness adjustability to meet the casting needs of tubular targets of different thicknesses.

[0088] In an embodiment, the baffle adjusting device is a height adjusting device, which adjusts the baffle 3 to different heights to regulate the distance between the baffle 3 and the inner wall of the centrifugal casting mold 1 .

[0089] In some embodiments, the baffle adjusting device is disposed at a connection position between the baffle 3 and the baffle bracket 31 , or the baffle adjusting device is disposed on the baffle bracket 31 .

[0090] like Figure 2 As shown, in the embodiment, the baffle 3 is arranged above the inner cavity bottom wall 11 of the centrifugal casting mold 1, the baffle 3 is perpendicular to the inner cavity bottom wall 11 of the centrifugal casting mold 1, the baffle 3 and the casting port 21 are arranged at intervals along the axial direction of the centrifugal casting mold 1, the baffle 3 extends along the axial direction of the centrifugal casting mold, and along the direction from the baffle 3 to the casting port 21, the baffle 3 is tilted toward the rotation direction of the bottom wall of the centrifugal casting mold 1, and the axial angle between the baffle and the centrifugal casting mold is 30°~60°.

[0091] In the description of this application, "the bottom wall rotation direction of the centrifugal casting mold 1" is as follows: Figure 2 In the figure, direction a is the tangent direction of the bottom wall of the centrifugal casting mold 1. When the centrifugal casting mold 1 rotates clockwise and counterclockwise, the bottom wall rotates in opposite directions. It should be noted that the centrifugal casting mold 1 is a rotatable structure. When it rotates, the position of the inner cavity bottom wall 11 of the centrifugal casting mold 1 can be determined according to the real-time state.

[0092] When the centrifugal casting mold 1 rotates, the inner cavity bottom wall 11 of the centrifugal casting mold 1 and the baffle 3 move relative to each other. At this time, the molten metal on the inner cavity bottom wall 11 of the centrifugal casting mold 1 that exceeds the set thickness is scraped off by the baffle 3. While the baffle 3 is scraping off the molten metal, the centrifugal casting mold 1 is axially displaced in a direction away from the casting runner 2. In order to prevent the molten metal from being scraped to the side of the baffle 3 away from the casting port 21 during the axial displacement of the centrifugal casting mold 1, the centrifugal casting device sets the baffle 3 at an angle. Specifically, along the direction from the baffle 3 to the casting port 21, the baffle 3 is tilted toward the rotation direction of the bottom wall of the centrifugal casting mold 1; thereby, during the relative movement of the baffle 3 and the centrifugal casting mold 1, a force (such as Figure 2As shown in b), the scraped molten metal is pushed toward the side of the casting port 21 to prevent the scraped molten metal from entering the side of the baffle plate 3 away from the casting port 21. During the axial displacement of the centrifugal casting mold 1, the flatness of the molten metal on the side of the baffle plate 3 away from the casting port 21 is ensured, which is beneficial to improve the overall thickness consistency of the cast tubular target.

[0093] In the embodiment, the casting channel 2 is a trough-shaped structure, the outer wall of the casting channel 2 is provided with a heat-insulating layer, and the bottom of the casting channel 2 is provided with an electric heating device.

[0094] By arranging a thermal insulation layer on the outer wall of the casting channel 2, the cooling rate of the molten metal in the casting channel 2 during the casting process can be reduced; at the same time, the electric heating device can provide additional heat supplement, thereby ensuring the temperature of the molten metal in the casting channel 2, avoiding the problem of solidification of the molten metal in the casting channel 2 causing blockage and a decrease in the casting flow rate, which is beneficial to ensuring the consistency of the flow rate of the molten metal during the casting process and improving the uniformity of the thickness of the tubular target material.

[0095] In an embodiment, the electric heating device is selected from a resistance heating wire.

[0096] In an embodiment, a supporting structure for supporting the casting runner 2 is further provided at the bottom of the casting runner 2 .

[0097] In the embodiment, the casting runner 2 is made of graphite or tungsten-molybdenum material and has the characteristic of high temperature resistance.

[0098] In the embodiment, a cover plate structure is provided on the top of the casting runner 2, and the top of the casting runner 2 is closed by the cover plate structure, so as to reduce heat loss.

[0099] In an embodiment, the centrifugal casting device further comprises a funnel 4, wherein the funnel 4 is connected to one end of the casting channel 2 located outside the centrifugal casting mold 1, and the casting channel 2 is tilted downward along the direction from the funnel 4 to the centrifugal casting mold 1.

[0100] The funnel 4 is provided to facilitate the introduction of the molten metal into the casting runner 2, thereby avoiding the problem of overflow or splashing of the molten metal due to excessive flow during the introduction process.

[0101] The casting runner 2 is tilted to facilitate utilizing gravity potential energy to make the molten metal in the casting runner 2 flow into the centrifugal casting mold 1, without the need to provide an additional driving device.

[0102] In an embodiment, the inclination angle between the casting channel 2 and the horizontal plane is 5°~60°. Considering that the casting channel 2 needs to extend into the centrifugal casting mold 1, when the length of the tubular target material to be cast is larger, the inclination angle of the casting channel 2 can be reduced to adapt to the centrifugal casting mold 1.

[0103] In an embodiment, the centrifugal casting device further includes a smelting chamber 6 and an intermediate frequency furnace 5 . The intermediate frequency furnace 5 and the funnel 4 are located in the smelting chamber 6 , and the funnel 4 is located below the intermediate frequency furnace 5 .

[0104] The intermediate frequency furnace 5 is used for smelting and mixing metal raw materials. The molten metal after smelting in the intermediate frequency furnace 5 enters the funnel 4 by drainage or pouring, and is then introduced into the casting runner 2 by the funnel 4 .

[0105] In an embodiment, the medium frequency furnace 5 comprises an induction coil and a crucible. The induction coil is located at the periphery of the crucible. The crucible and the induction coil are used for heating and melting metal raw materials.

[0106] In an embodiment, the centrifugal casting device also includes a vacuum pumping device and a protective gas supply device. The vacuum pumping device is used to remove the air in the medium frequency furnace 5, and the protective gas supply device is used to introduce protective gas into the medium frequency furnace 5. The protective gas can be selected from gases that do not react with the molten metal, such as argon. The vacuum pumping device and the protective gas supply device can prevent the metal raw material or the molten metal from reacting with oxygen and water vapor in the air during the smelting process, thereby preventing the quality of the cast tubular target material.

[0107] In an embodiment, the centrifugal casting device also includes a casting chamber 9, which is arranged adjacent to the smelting chamber 6, the rotating mechanism, the centrifugal casting mold 1 and the baffle 3 are located in the casting chamber 9, and the casting runner 2 extends from the smelting chamber 6 to the casting chamber 9.

[0108] The casting chamber 9 is provided to avoid interference of the external environment with the centrifugal casting process. Since the centrifugal casting mold 1 performs axial displacement during the centrifugal casting process, the casting chamber 9 can also avoid interference between the centrifugal casting mold 1 and the external structure during the axial displacement process, thereby improving safety. On the other hand, the casting chamber 9 is also conducive to the control of environmental factors during the casting process of the centrifugal casting mold 1, thereby avoiding excessive fluctuations in environmental conditions.

[0109] The technical solution of the present application is further described below in conjunction with specific embodiments.

[0110] Example 1

[0111] The raw materials of terbium, praseodymium, aluminum and copper were prepared in a mass ratio of 60 / 20 / 10 / 10. A total of 23 kg of materials were put into the medium frequency furnace and vacuumed to 2×10 -3 After Pa, high-purity argon gas is filled for protection, and the temperature is raised to 1500℃ and insulation is started. After observing that all the metal is melted, insulation is started for 10 minutes. After being cast into the funnel, the molten metal is introduced into the casting runner through the funnel, and the casting runner is heated to keep its temperature at 900℃. The centrifugal casting equipment is started with a rotation speed of 1000rps. The molten metal in the casting runner is introduced into the centrifugal casting mold with a hollow cylindrical structure through the casting port. A baffle is set above the bottom wall of the inner cavity of the centrifugal casting mold. The baffle and the casting port are spaced apart along the axial direction of the centrifugal casting mold. The casting port and the baffle are kept in fixed position. Centrifugal casting The mold is displaced axially (from the casting port to the baffle), and the molten metal cast from the casting port forms a casting tube section under the action of centrifugal force. The molten metal exceeding the preset thickness on the newly formed casting tube section is scraped off by the baffle. From the baffle to the casting port, the baffle is tilted toward the bottom wall rotation direction of the centrifugal casting mold. 5 minutes after the molten metal is cast, the speed of the casting equipment is adjusted to 500rps and maintained at this speed for 20 minutes. The quaternary alloy tube target is demolded after cooling with the furnace, and the tube target with specifications of OD160×ID140×L400mm is obtained after machining.

[0112] Example 2

[0113] The raw materials of terbium, praseodymium and aluminum were prepared in a mass ratio of 70 / 20 / 10. A total of 23 kg of materials were put into the medium frequency furnace and vacuumed to 2×10 -3 After Pa, high-purity argon gas is filled for protection, the temperature is raised to 1450℃ and insulation is started. After observing that the metal is completely melted, insulation is started for 10 minutes. After being cast into the funnel, the molten metal is introduced into the casting runner through the funnel, the casting runner is heated to keep its temperature at 850℃, the centrifugal casting equipment is started, the speed is 900rps, and the molten metal in the casting runner is introduced into the centrifugal casting mold with a hollow cylindrical structure through the casting port, a baffle is set above the bottom wall of the inner cavity of the centrifugal casting mold, the baffle and the casting port are spaced apart along the axial direction of the centrifugal casting mold, the casting port and the baffle are kept in fixed position, and the centrifugal casting mold The mold is displaced along the axial direction (from the casting port to the baffle), and the molten metal cast from the casting port forms a casting tube section under the action of centrifugal force. The molten metal exceeding the preset thickness on the newly formed casting tube section is scraped off by the baffle, and the baffle is tilted toward the bottom wall of the centrifugal casting mold in the direction from the baffle to the casting port. 5 minutes after the molten metal is cast, the speed of the casting equipment is adjusted to 450rps, and the speed is maintained for 20 minutes. The furnace is cooled and demolded to obtain a ternary alloy tube target. After machining, a tube target with specifications of OD160×ID140×L400mm is obtained.

[0114] Example 3

[0115] 23 kg of pure terbium metal was placed in a medium frequency furnace and vacuumed to 2×10 -3 After Pa, high-purity argon gas is filled for protection, and the temperature is raised to 1600℃ and insulation is started. After observing that all the metal is melted, insulation is started for 10 minutes. After being cast into the funnel, the molten metal is introduced into the casting runner through the funnel, and the casting runner is heated to keep its temperature at 1100℃. The centrifugal casting equipment is started with a rotation speed of 800rps. The molten metal in the casting runner is introduced into the centrifugal casting mold with a hollow cylindrical structure through the casting port. A baffle is set above the bottom wall of the inner cavity of the centrifugal casting mold. The baffle and the casting port are spaced apart along the axial direction of the centrifugal casting mold. The casting port and the baffle are kept in fixed position. Centrifugal casting The mold is displaced axially (from the casting port to the baffle), and the molten metal cast from the casting port forms a casting tube section under the action of centrifugal force. The molten metal exceeding the preset thickness on the newly formed casting tube section is scraped off by the baffle. From the baffle to the casting port, the baffle is tilted toward the bottom wall of the centrifugal casting mold in the direction of rotation. 5 minutes after the molten metal is cast, the speed of the casting equipment is adjusted to 400rps and maintained at the speed for 20 minutes. The casting equipment is cooled with the furnace and demolded to obtain a single metal tube target. After machining, a tube target with specifications of OD160×ID140×L300mm is obtained.

[0116] Example 4

[0117] The raw materials of terbium, praseodymium, aluminum and copper were prepared in a mass ratio of 60 / 20 / 10 / 10. A total of 23 kg of materials were put into the medium frequency furnace and vacuumed to 2×10 -3 After the temperature reaches 1500℃, high-purity argon gas is filled for protection. The temperature is raised to 1500℃ and insulation is started. After observing that all the metal is melted, insulation is started for 10 minutes. After being cast into the funnel, the molten metal is introduced into the casting runner through the funnel. The casting runner is heated to keep its temperature at 900℃. The centrifugal casting equipment is started with a rotation speed of 1000rps. The molten metal in the casting runner is introduced into the centrifugal casting mold with a hollow cylindrical structure through the casting port. A baffle is set above the bottom wall of the inner cavity of the centrifugal casting mold. The baffle and the casting port are spaced apart along the axial direction of the centrifugal casting mold. The casting port and the baffle are kept in fixed position. The centrifugal casting mold is displaced axially (from the casting port to the baffle), and the molten metal cast from the casting port forms a casting tube section under the action of centrifugal force. The molten metal exceeding the preset thickness on the newly formed casting tube section is scraped off by the baffle, and no deflection is set along the baffle to the casting port. 5 minutes after the molten metal is cast, the speed of the casting equipment is adjusted to 500rps, and the speed is maintained for 20 minutes. The furnace is cooled and the quaternary alloy tube target is demoulded to obtain a tube target with specifications of OD160×ID140×L400mm after machining.

[0118] Comparative Example 1

[0119] The raw materials of terbium, praseodymium, aluminum and copper were prepared in a mass ratio of 60 / 20 / 10 / 10. A total of 23 kg of materials were put into the medium frequency furnace and vacuumed to 2×10 -3 After Pa, high-purity argon gas is filled for protection, and the temperature is raised to 1500℃ and insulation is started. After observing that all the metal is melted, insulation is started for 10 minutes. After being cast into the funnel, the molten metal is introduced into the casting runner through the funnel, the casting runner is heated to keep its temperature at 900℃, and the centrifugal casting equipment is started with a rotation speed of 1000rps. The molten metal in the casting runner is introduced into the centrifugal casting mold with a hollow cylindrical structure through the casting port. The casting port remains in a fixed position, and the centrifugal casting mold is displaced axially. The molten metal cast from the casting port forms a casting pipe section under the action of centrifugal force. 5 minutes after the casting of the molten metal is completed, the rotation speed of the casting equipment is adjusted to 500rps, and the rotation speed is maintained for 20 minutes. The quaternary alloy tube target is obtained by demolding, and the tube target with specifications of OD160×ID140×L400mm is obtained after machining.

[0120] Comparative Example 2

[0121] Metal terbium, metal praseodymium, metal aluminum and metal copper powders are used as raw materials with a particle size range of 25~50μm. 23kg of raw materials are configured according to the mass ratio of 60 / 20 / 10 / 10, and are loaded into a rubber sleeve of OD170×ID130×L500mm under argon protection. After vibration compaction, the blank is obtained by isostatic pressing. The blank is sintered at 700℃ in a vacuum sintering furnace, kept warm for 2h and then cooled. After machining, a tube target with a specification of OD160×ID140×L400mm is obtained.

[0122] Related performance test analysis:

[0123] The following tests were performed on the tube targets prepared in the examples and comparative examples:

[0124] 1. Take points on the tube target at intervals of 10 mm to test the tube wall thickness, and obtain multiple sets of thickness test values. The difference between the point value with the largest thickness and the point value with the smallest thickness is taken as the thickness range of the tube target, and recorded in Table 1;

[0125] 2. Detect the oxygen content and relative density of the tube target. The test results are recorded in Table 1.

[0126] Table 1

[0127]

[0128] It can be seen from the test results of Examples 1 to 4 and Comparative Example 2 that, compared with the tube targets obtained by the existing powder die-casting method, the tube targets obtained by centrifugal casting in the present application can effectively improve the relative density of the tube targets, reduce the pores inside the tube targets, and thus effectively reduce the oxygen content of the tube targets and improve the quality of the target materials.

[0129] It can be seen from the test results of Examples 1 to 4 and Comparative Example 1 that by arranging a baffle in the centrifugal casting mold and axially displacing the centrifugal casting mold relative to the casting port and the baffle during the casting process, the molten metal exceeding the preset thickness on the casting pipe section can be effectively scraped off, thereby ensuring the overall thickness uniformity of the tube target obtained by casting. At the same time, it can be seen from the data that the baffle exerts a force on the molten metal during the rotation process, which is also beneficial to reducing the pores inside the tube target, thereby reducing the oxygen content of the tube target, increasing its relative density, and improving the application quality of the target material.

[0130] It can be seen from the test results of Examples 1 to 3 and Example 4 that by setting the baffle at an angle, it is beneficial to apply a force toward the casting port to the scraped molten metal during the axial displacement of the centrifugal casting mold, push the scraped molten metal toward the casting port, improve the flatness of the casting pipe section that has been scraped, and help improve the overall thickness consistency of the tubular target material obtained by casting.

[0131] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a tubular target material, It is characterized in that The steps include: Obtaining molten metal; The molten metal is introduced into a centrifugal casting mold with a hollow cylindrical structure through a casting port, a baffle is arranged above the bottom wall of the inner cavity of the centrifugal casting mold, the baffle and the casting port are arranged at intervals along the axial direction of the centrifugal casting mold, the baffle extends along the axial direction of the centrifugal casting mold, and along the direction from the baffle to the casting port, the baffle is inclined toward the rotation direction of the bottom wall of the centrifugal casting mold, and the axial angle between the baffle and the centrifugal casting mold is 30°~60°. During the casting process, the centrifugal casting mold rotates around its central axis while displacing along the axial direction, the centrifugal casting mold displaces along the direction from the casting port to the baffle, the casting port and the baffle are kept in fixed positions, the molten metal cast from the casting port forms a casting pipe section under the action of centrifugal force, and during the displacement of the centrifugal casting mold, a force toward the casting port is applied to the scraped molten metal through the baffle, so that the scraped molten metal is pushed toward one side of the casting port; After cooling, demoulding and obtaining a tubular target material.

2. The method for preparing a tubular target according to claim 1, It is characterized in that During the casting process, the rotation speed of the centrifugal casting mold is 700~1000 rps, and the axial displacement speed is 1~5cm / s.

3. The method for preparing a tubular target according to claim 1, It is characterized in that During the casting process, the molten metal is guided to the casting port through the casting runner, and the casting runner is subjected to insulation and heating treatment. The temperature of the molten metal in the casting runner is maintained at 700-1100°C.

4. The method for preparing a tubular target according to any one of claims 1 to 3, It is characterized in that During the cooling process, the rotation speed of the centrifugal casting mold is reduced to 300~500rps, and the rotation is kept for 10~20min before stopping, and the mold is demolded after continuous cooling.

5. The method for preparing a tubular target according to claim 1, It is characterized in that The step of obtaining the molten metal includes: smelting and mixing the metal raw materials, and the smelting process is carried out in a vacuum or protective gas to obtain the molten metal.

6. The method for preparing a tubular target according to claim 1, It is characterized in that The molten metal includes rare earth metals and optionally transition metals, the rare earth metals include at least one of terbium, dysprosium, and praseodymium, and the transition metals include at least one of aluminum and copper. Based on the total mass of the molten metal as 100%, the mass percentage of the rare earth metal is 60% to 100%, and the mass percentage of the transition metal is 0 to 40%.

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