Heat treatment device for multi-step sintering of Bi-series superconducting powder

Abstract

The invention discloses a heat treatment device for multi-step sintering of Bi-series superconductive powder, which comprises a rotary furnace tube, bearing furnace tube supports for supporting the rotary furnace tube are arranged at two ends of the rotary furnace tube, a gear ring is arranged at one end of the rotary furnace tube and connected with a gear driven by a motor, and a main heating body is wrapped in the middle of the rotary furnace tube. The two sides of the main heating body are each provided with an auxiliary heating body wrapping the rotary furnace tube, and a detachable powder inner container is installed in the rotary furnace tube. The rotary furnace tube is arranged to be matched with the detachable powder inner container to rotate, the main heating body and the auxiliary heating body are arranged to evenly heat powder in the detachable powder inner container, continuous multi-stage sintering customization is conducted on Bi-series superconducting powder, uniform distribution and the sintering effect of the Bi-series superconducting powder in the sintering process are guaranteed, and the sintering efficiency is improved. And the uniformity of the heating temperature is ensured, the powder filling and sintering efficiency is optimized, and uniform sintering of a large amount of powder becomes possible.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of Bi-based high-temperature superconducting wire strips, and in particular relates to a heat treatment device for multi-step sintering of Bi-based superconducting powders. Background Art

[0002] Bi-based high-temperature superconducting wires have great application prospects in magnetic confinement fusion, superconducting cables, superconducting transformers, superconducting fault current limiters and superconducting transformers. Precursor powder is the most important raw material for Bi-based superconducting wire strips and has the most important influence on the current carrying performance of superconducting wire strips. The uniformity of precursor powder is the most important indicator of precursor powder.

[0003] At present, Bi-based superconducting precursor powders are generally sintered statically with gradually increasing temperatures in a box furnace or a tube furnace. During the sintering process, the gas at the bottom of the powder is difficult to diffuse out, resulting in a different atmosphere for the bottom powder than other locations, causing incomplete reaction of the bottom powder. To solve this problem, two measures are generally taken. First, the thickness of the sintered powder is controlled to be less than 1.5 cm; second, the heat treatment time is extended to allow the bottom gas to diffuse to the outside, and the high-temperature insulation time of each step is generally controlled to be more than 20 hours. Through the above scheme, the quality of the precursor powder has been improved to a certain extent, but the unevenness of the precursor powder can still be found. At the same time, the thickness of the powder is too thin, which significantly affects the yield, and the extension of the heat treatment time causes a substantial increase in energy consumption (it generally takes 8 steps to complete the sintering of the Bi-based precursor powder, and each step is kept at the highest temperature for more than 20 hours). Many process changes were made later, but it still could not meet the requirements of sintering a large amount of uniform powder.

[0004] In summary, exploring an efficient device or innovative solution to effectively solve the problem of exhaust gas emissions from the bottom of the sintering boat during the sintering process and realize rapid external replacement of the bottom powder is of great significance for improving the performance and production capacity of precursor powders and promoting the development of Bi-based superconducting powders. It is the key direction of current research in this field. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a heat treatment device for multi-step sintering of Bi-based superconducting powders in view of the deficiencies of the above-mentioned prior art. The device is provided with a rotating furnace tube that rotates in conjunction with a detachable powder liner, and a main heating body and an auxiliary heating body are provided to uniformly heat the powder inside the detachable powder liner, thereby ensuring the uniform distribution and sintering effect of the Bi-based superconducting powder during the sintering process, ensuring the uniformity of the heating temperature, greatly improving the uniformity of the Bi-based superconducting powder after heat treatment, further optimizing the filling and sintering efficiency of the powder, and making it possible to uniformly sinter a large amount of powder.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a heat treatment device for multi-step sintering of Bi-based superconducting powder, characterized in that the device includes a rotating furnace tube, both ends of the rotating furnace tube are provided with bearing furnace tube brackets for supporting the rotating furnace tube, one end of the rotating furnace tube is also provided with a gear ring, the gear ring is connected to the gear driven by a motor, the middle part of the rotating furnace tube is wrapped with a main heating body, both sides of the main heating body are provided with auxiliary heating bodies wrapped on the rotating furnace tube, and a removable powder liner is installed in the rotating furnace tube.

[0007] The above-mentioned heat treatment device for multi-step sintering of Bi-based superconducting powder is characterized in that the rotary furnace tube is made of 310S stainless steel with a wall thickness greater than 7 mm.

[0008] The above-mentioned heat treatment device for multi-step sintering of Bi-based superconducting powder is characterized in that the length of the main heating body is the same as the length of the detachable powder inner liner, the inner diameter of the main heating body and the inner diameter of the auxiliary heating body are matched with the outer diameter of the rotating furnace tube, and the length of the auxiliary heating body is not less than the inner diameter of the auxiliary heating body.

[0009] The above-mentioned heat treatment device for multi-step sintering of Bi-based superconducting powder is characterized in that the detachable powder liner includes a main storage area cylinder, and three inclined material shifting plates are installed inside the main storage area cylinder. The length of the material shifting plate is equal to the length of the main storage area cylinder, the thickness is not less than 4mm, the height is not less than 1 / 5 of the inner diameter of the main storage area cylinder, and the inclination angle is 3°~5°. Open conical cylinders are installed on both sides of the main storage area cylinder, the top angle and bottom angle of the open conical cylinder are both 45°, and the opening diameter is 1 / 3 of the inner diameter of the main storage area cylinder.

[0010] In addition, the present invention also provides a method for using a heat treatment device for multi-step sintering of Bi-based superconducting powder, characterized in that the method comprises the following steps:

[0011] Step 1: Load Bi-based superconducting powder into a removable powder container;

[0012] Step 2: The detachable powder liner containing Bi-based superconducting powder in step 1 is fixedly installed in the rotary furnace tube, and then the motor is turned on to drive the rotary furnace tube to rotate, and the main heating body and the auxiliary heating body are turned on to perform a multi-step sintering heat treatment on the Bi-based superconducting powder;

[0013] Step 3: After the multi-step sintering heat treatment in step 2 is completed, the detachable powder liner is taken out, and then the Bi-based superconducting powder after the heat treatment is poured out.

[0014] The present invention loads Bi-based superconducting powder into a detachable powder liner and performs a rotating and uniform multi-step sintering heat treatment, thereby maintaining continuous dynamic stirring of the Bi-based superconducting powder throughout the multi-step sintering process, and completely solves the problem of uneven sintering of powder at the bottom of the sintering boat in traditional sintering. After each step of sintering is completed, the Bi-based superconducting powder does not need complicated cooling, taking out, stirring and heating again, but can directly and smoothly enter the next high-temperature insulation stage. Through a simple heating cycle, continuous multi-step sintering can be efficiently completed, which not only significantly improves the sintering uniformity of the Bi-based superconducting powder, but also greatly reduces energy consumption, manpower investment and time cost, optimizes the filling and sintering efficiency of the Bi-based superconducting powder, and makes uniform sintering of a large amount of powder possible.

[0015] The above method is characterized in that the rotation speed in step 2 is 1 r / min to 5 r / min. The present invention controls the stirring speed of the material plate in the detachable powder liner on the Bi-based superconducting powder by controlling the rotation speed, thereby improving the uniformity of sintering.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The present invention arranges a rotating furnace tube to rotate with a detachable powder liner, and arranges a main heating body and an auxiliary heating body to uniformly heat the powder inside the detachable powder liner, thereby ensuring the uniform distribution and sintering effect of the Bi-based superconducting powder during the sintering process, ensuring the uniformity of the heating temperature, greatly improving the uniformity of the Bi-based superconducting powder after heat treatment, further optimizing the filling and sintering efficiency of the powder, and making it possible to uniformly sinter a large amount of powder.

[0018] 2. The present invention provides a rotating furnace tube and a material stripping plate inside a detachable powder liner to maintain continuous dynamic stirring of the Bi-based superconducting powder during the entire sintering process, which completely solves the problem of uneven sintering of powder at the bottom of the sintering boat in traditional sintering. After each step of sintering, the Bi-based superconducting powder does not require cumbersome cooling, taking out, stirring and heating again, but can directly and smoothly enter the next high-temperature insulation stage. Through a simple heating cycle, continuous multi-step sintering can be efficiently completed, which not only significantly improves the sintering uniformity of the Bi-based superconducting powder, but also greatly reduces energy consumption, manpower investment and time costs.

[0019] 3. The present invention ensures the continuous stirring and uniform heating of Bi-based superconducting powders during the sintering process, so that all Bi-based superconducting powders can be fully sintered, thereby greatly shortening the necessary insulation time. Compared with the traditional method that requires insulation for 20 hours, the present invention only takes 2 hours to achieve the same or even better sintering effect, thereby improving the production efficiency of Bi-based superconducting powders, reducing the batch production time from 14 days / batch to 1 day / batch, and increasing the output of a single furnace.

[0020] 4. The design of the heat treatment device for multi-step sintering of Bi-based superconducting powder of the present invention fully considers the actual production needs. It has a simple structure, convenient operation, and is easy to integrate with existing production lines, providing strong technical support for the industrial production of Bi-based powder sintering.

[0021] 5. The heat treatment device for multi-step sintering of Bi-based superconducting powders of the present invention performs well in improving sintering efficiency, reducing costs, shortening production cycles and promoting industrial applications, bringing revolutionary progress to the sintering technology of Bi-based powders.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of the heat treatment device for multi-step sintering of Bi-based superconducting powders of the present invention.

[0024] Figure 2 The present invention is a schematic structural diagram of a detachable powder liner in a heat treatment device for multi-step sintering of Bi-based superconducting powders.

[0025] Figure 3 Schematic diagram of the unfolded structure of the cylinder in the main material storage area of ​​the detachable powder liner of the present invention

[0026] Description of reference numerals:

[0027] 1—rotating furnace tube; 2—bearing furnace tube bracket; 3—gear ring;

[0028] 4—main heating element; 5—auxiliary heating element; 6—detachable powder liner;

[0029] 7—Cylinder in the main storage area; 8—Material shifting plate; 9—Conical cylinder. DETAILED DESCRIPTION

[0030] A heat treatment device for multi-step sintering of Bi-based superconducting powders of the present invention is described in detail through Example 1.

[0031] Example 1

[0032] like Figure 1As shown, a heat treatment device for multi-step sintering of Bi-based superconducting powder in this embodiment includes a rotating furnace tube 1, both ends of the rotating furnace tube 1 are provided with bearing furnace tube brackets 2 for supporting the rotating furnace tube 1, one end of the rotating furnace tube 1 is also provided with a gear ring 3, the gear ring 3 is connected to a gear driven by a motor, a main heating body 4 is wrapped in the middle of the rotating furnace tube 1, auxiliary heating bodies 5 wrapped on the rotating furnace tube 1 are provided on both sides of the main heating body 4, and a detachable powder liner 6 is installed in the rotating furnace tube 1.

[0033] It should be noted that, by setting up a rotating furnace tube 1, it is used to install a removable powder liner 6, and cooperates with the rotation and the main heating body 4 and the auxiliary heating body 5 to uniformly heat the powder inside the removable powder liner 6, and facilitates the loading and unloading of Bi-based superconducting powder, wherein the main heating body 4 mainly heats the powder inside the removable powder liner 6, and the auxiliary heating body 5 is used to ensure that the temperature of each part in the rotating furnace tube 1 is uniform, thereby ensuring the uniformity of the heating temperature and greatly improving the uniformity of the Bi-based superconducting powder after heat treatment. Compared with the traditional method that requires insulation for 20 hours, the present invention only takes 2 hours to achieve the same or even better sintering effect, thereby improving the production efficiency of Bi-based superconducting powder and the output of a single furnace.

[0034] It should be noted that the auxiliary heating body 5 is heated so that the temperature of the area of ​​the rotating furnace tube 1 heated by the auxiliary heating body 5 is higher than the temperature of the area of ​​the rotating furnace tube 1 heated by the main heating body 4, so as to avoid the problem of too short constant temperature zone caused by too rapid temperature drop. Under the condition of the same length of the main heating body 4, the constant temperature zone of the auxiliary heating body 5 is set to be longer, and the comprehensive energy consumption of sintering Bi-based superconducting powder is also lower.

[0035] It should be noted that the bearing furnace tube bracket 2 is provided to support the rotating furnace tube 1 so that the axis of the rotating furnace tube 1 coincides with the central axis of the main heating body 4 and the auxiliary heating body 5, thereby ensuring that the rotating furnace tube 1 has a maximum constant temperature zone. At the same time, a gear ring 3 is provided at one end of the rotating furnace tube 1 and on the inner side of the bearing furnace tube bracket 2. The gear ring 3 is connected to the gear driven by the motor, thereby realizing the rotation of the rotating furnace tube 1.

[0036] It should be noted that the rotary furnace tube 1 is connected to the detachable powder liner 6 via a conical fastening pin, and the inner wall of the rotary furnace tube 1 is provided with a semicircular groove for installing the conical fastening pin.

[0037] In this embodiment, the rotary furnace tube 1 is made of 310S stainless steel with a wall thickness greater than 7 mm. By controlling the material and thickness of the rotary furnace tube 1, it has excellent mechanical properties and anti-oxidation properties at high temperatures, while also ensuring sintering uniformity.

[0038] like Figure 1As shown, in this embodiment, the length of the main heating body 4 is the same as the length of the detachable powder liner 6, the inner diameter of the main heating body 4 and the inner diameter of the auxiliary heating body 5 are matched with the outer diameter of the rotary furnace tube 1, and the length of the auxiliary heating body 5 is not less than the inner diameter of the auxiliary heating body 5. By controlling the length of the main heating body 4 to be the same as the length of the detachable powder liner 6, the detachable powder liner 6 is completely within the heating range of the main heating body 4, ensuring that the Bi-based superconducting powder inside the detachable powder liner 6 is heated evenly, and more Bi-based superconducting powder can be sintered. By controlling the inner diameters of the main heating body 4 and the inner diameters of the auxiliary heating body 5 to match the outer diameter of the rotary furnace tube 1, the heating effect is further improved. By controlling the length of the auxiliary heating body 5 to be not less than the inner diameter of the auxiliary heating body 5, the heating area of ​​the auxiliary heating body 5 is guaranteed, the overall heating effect is guaranteed, and thus the constant temperature of the heating is guaranteed.

[0039] like Figure 2 and Figure 3 As shown, in this embodiment, the detachable powder liner 6 includes a main storage area cylinder 7, and three inclined material shifting plates 8 are installed inside the main storage area cylinder 7. The length of the material shifting plates 8 is equal to the length of the main storage area cylinder 7, the thickness is not less than 4 mm, the height is not less than 1 / 5 of the inner diameter of the main storage area cylinder 7, and the inclination angle is 3°~5°. Open conical cylinders 9 are installed on both sides of the main storage area cylinder 7, and the top angle and bottom angle of the open conical cylinder 9 are both 45°, and the opening diameter is 1 / 3 of the inner diameter of the main storage area cylinder 7. The main storage area cylinder 7 is provided for placing Bi-based superconducting powder, and three inclined material shifting plates 8 are provided. When the rotating furnace tube 1 drives the detachable powder inner container 6 to rotate, the material shifting plates 8 drive the Bi-based superconducting powder to rotate, and when the material shifting plates 8 are tilted downward at an angle greater than 45°, the Bi-based superconducting powder will tilt and fall from the upper material shifting plates 8. In the process of the rotating furnace tube 1 driving the detachable powder inner container 6 to rotate, the above process is repeated continuously, thereby achieving uniform sintering of the Bi-based superconducting powder. By controlling the length, thickness, height, and width of the material shifting plates 8, the Bi-based superconducting powder can be uniformly sintered. By adjusting the angle of inclination and the angle of tilt, all Bi-based superconducting powders in the main storage area cylinder 7 can be fully stirred, thereby improving the uniformity of heating. By setting the open conical cylinder 9 and controlling the size of the open conical cylinder 9, the Bi-based superconducting powders are kept in the area of ​​the main storage area cylinder 7 during the rotation of the rotating furnace tube 1 driving the detachable powder liner 6 to rotate. While improving the uniformity of heating, the Bi-based superconducting powder is prevented from leaking out and contaminating the rotating furnace tube 1, and the Bi-based superconducting powder after heat treatment can be completely poured out to avoid the residue of Bi-based superconducting powder.

[0040] The use method of the heat treatment device for multi-step sintering of Bi-based superconducting powder of the present invention is described in detail through Examples 2 to 4.

[0041] Example 2

[0042] This embodiment includes the following steps:

[0043] Step 1: Load Bi-based superconducting powder into the removable powder container 6;

[0044] Step 2: The detachable powder liner 6 containing the Bi-based superconducting powder in step 1 is fixedly installed in the rotary furnace tube 1, and then the motor is turned on to drive the rotary furnace tube 1 to rotate at a speed of 3 r / min, and the main heating body 4 and the auxiliary heating body 5 are turned on to perform a multi-step sintering heat treatment on the Bi-based superconducting powder;

[0045] Step 3: After the multi-step sintering heat treatment in step 2 is completed, the detachable powder liner 6 is taken out, and then the Bi-based superconducting powder after the heat treatment is poured out.

[0046] According to the test, the Bi-based superconducting powder prepared in this embodiment after the heat treatment is heated evenly.

[0047] Example 3

[0048] This embodiment includes the following steps:

[0049] Step 1: Load Bi-based superconducting powder into the removable powder container 6;

[0050] Step 2: The detachable powder liner 6 containing the Bi-based superconducting powder in step 1 is fixedly installed in the rotary furnace tube 1, and then the motor is turned on to drive the rotary furnace tube 1 to rotate at a speed of 5 r / min, and the main heating body 4 and the auxiliary heating body 5 are turned on to perform a multi-step sintering heat treatment on the Bi-based superconducting powder;

[0051] Step 3: After the multi-step sintering heat treatment in step 2 is completed, the detachable powder liner 6 is taken out, and then the Bi-based superconducting powder after the heat treatment is poured out.

[0052] According to the test, the Bi-based superconducting powder prepared in this embodiment after the heat treatment is heated evenly.

[0053] Example 4

[0054] This embodiment includes the following steps:

[0055] Step 1: Load Bi-based superconducting powder into the removable powder container 6;

[0056] Step 2: The detachable powder liner 6 containing the Bi-based superconducting powder in step 1 is fixedly installed in the rotary furnace tube 1, and then the motor is turned on to drive the rotary furnace tube 1 to rotate at a speed of 1 r / min, and the main heating body 4 and the auxiliary heating body 5 are turned on to perform a multi-step sintering heat treatment on the Bi-based superconducting powder;

[0057] Step 3: After the multi-step sintering heat treatment in step 2 is completed, the detachable powder liner 6 is taken out, and then the Bi-based superconducting powder after the heat treatment is poured out.

[0058] According to the test, the Bi-based superconducting powder prepared in this embodiment after the heat treatment is heated evenly.

[0059] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent changes made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A heat treatment device for multi-step sintering of Bi-based superconducting powder, characterized in that: The device comprises a rotating furnace tube (1), both ends of the rotating furnace tube (1) are provided with bearing furnace tube brackets (2) for supporting the rotating furnace tube (1), one end of the rotating furnace tube (1) is also provided with a gear ring (3), the gear ring (3) is connected to a gear driven by a motor, a main heating body (4) is wrapped around the middle of the rotating furnace tube (1), auxiliary heating bodies (5) wrapped around the rotating furnace tube (1) are provided on both sides of the main heating body (4), and a detachable powder liner (6) is installed in the rotating furnace tube (1).

2. A heat treatment device for multi-step sintering of Bi-based superconducting powder according to claim 1, characterized in that: The rotary furnace tube (1) is made of 310S stainless steel with a wall thickness greater than 7 mm.

3. A heat treatment device for multi-step sintering of Bi-based superconducting powder according to claim 1, characterized in that: The length of the main heating body (4) is the same as the length of the detachable powder inner container (6), the inner diameter of the main heating body (4) and the inner diameter of the auxiliary heating body (5) both match the outer diameter of the rotary furnace tube (1), and the length of the auxiliary heating body (5) is not less than the inner diameter of the auxiliary heating body (5).

4. A heat treatment device for multi-step sintering of Bi-based superconducting powder according to claim 1, characterized in that: The detachable powder liner (6) comprises a main material storage area cylinder (7), three inclined material shifting plates (8) are installed inside the main material storage area cylinder (7), the length of the material shifting plates (8) is equal to the length of the main material storage area cylinder (7), the thickness is not less than 4 mm, the height is not less than 1 / 5 of the inner diameter of the main material storage area cylinder (7), and the inclination angle is 3° to 5°. Open conical cylinders (9) are installed on both sides of the main material storage area cylinder (7), the top angle and bottom angle of the open conical cylinder (9) are both 45°, and the opening diameter is 1 / 3 of the inner diameter of the main material storage area cylinder (7).

5. A heat treatment method for multi-step sintering of Bi-based superconducting powder using the apparatus according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: Step 1: Loading Bi-based superconducting powder into a removable powder liner (6); Step 2: The detachable powder liner (6) containing the Bi-based superconducting powder in step 1 is fixedly installed in the rotary furnace tube (1), and then the motor is turned on to drive the rotary furnace tube (1) to rotate, and the main heating body (4) and the auxiliary heating body (5) are turned on to perform a multi-step sintering heat treatment on the Bi-based superconducting powder; Step 3: After the multi-step sintering heat treatment in step 2 is completed, the detachable powder liner (6) is taken out, and then the Bi-based superconducting powder after the heat treatment is poured out.

6. The method according to claim 5, characterized in that The rotation speed in step 2 is 1 r / min to 5 r / min.

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