An ultrafine aluminum nitride powder preparation device and method thereof
By setting cylindrical and conical column structures on the end cap of the ball mill jar, the problem of end cap wear caused by poor material flow in the ball mill jar is solved, the durability and ease of disassembly and assembly of the end cap are achieved, and the efficient preparation of ultrafine aluminum nitride powder is ensured.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN HUAQING ELECTRONICS MATERIAL TECH
- Filing Date
- 2026-05-07
- Publication Date
- 2026-06-05
AI Technical Summary
The existing ball mill jar has a height difference between the end cap and the inner wall of the ball mill jar, which makes it impossible for the material to flow smoothly during rotation, resulting in severe wear of the end cap, short service life, and inconvenience in disassembly and assembly.
Multiple cylindrical and conical structures are installed on the end cap of the ball mill jar. The cylindrical structures block and buffer the material, slowing it down and preventing direct impact. The conical structures adjust the flow area of the vent holes, enabling smooth material movement and reducing impact force.
It extends the service life of the end caps, reduces the risk of wear, improves the ease of disassembly and assembly, and ensures the stability of the ball milling process and the uniformity of the powder.
Smart Images
Figure CN122141812A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultrafine aluminum nitride powder preparation technology, specifically to an apparatus and method for preparing ultrafine aluminum nitride powder. Background Technology
[0002] Aluminum nitride (AlN), as a high-performance advanced ceramic material, has product quality highly dependent on the quality of its raw material powder. The particle size distribution and purity level of the powder directly determine the density, thermal conductivity, and mechanical properties of the final aluminum nitride ceramic. In the industrial production of ultrafine aluminum nitride powder, ball milling is a key process for achieving raw material refinement and homogenization, and the structure and durability of the ball mill jar are crucial for stable production. In actual production, the aluminum source material and grinding media are usually loaded into the ball mill jar together, and the inlet and outlet of the ball mill jar are sealed with end caps. Then, the ball mill jar is driven by a motor to rotate, and powder refinement is achieved through the impact and grinding of the media.
[0003] Due to the significant height difference between the end cap and the inner wall of the mill jar, the inner wall of the end cap cannot smoothly transition with the curved inner wall of the mill jar to form a continuous curved surface, hindering the smooth flow of material inside the jar during rotation. The aluminum source material and grinding media move along the jar wall under centrifugal force and gravity, directly impacting the inner wall of the end cap at high speed, creating continuous and intense impact and scouring. Long-term impact causes rapid wear, deformation, and even localized peeling of the end cap surface, accelerating end cap wear, shortening its service life, and necessitating the use of thicker end caps, making end cap assembly and disassembly inconvenient. Summary of the Invention
[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an apparatus and method for preparing ultrafine aluminum nitride powder, so as to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: an ultrafine aluminum nitride powder preparation device, comprising a ball mill jar, wherein an inlet and outlet are provided on the outer surface of the ball mill jar, and a frame connected and fixed to the ball mill jar is provided outside the inlet and outlet. An end cap is connected to the end of the frame away from the ball mill jar by multiple sets of bolts. Multiple circular openings are evenly provided on one side of the end cap, and a straight cylinder is installed in each of the multiple circular openings. A guide hole is provided at the center of the side of the straight cylinder facing the center region of the ball mill jar, and the portion of the straight cylinder away from the guide hole is located at the point where the circular openings are away from the center region of the ball mill jar. On one side, a cylinder is inserted into the guide hole. The side of the cylinder away from the straight cylinder has a hemispherical groove for temporarily storing the material inside the grinding jar. After the material in the grinding jar slows down due to the obstruction of multiple cylinders, it moves to contact the end cap. The end of the cylinder away from the hemispherical groove extends into the straight cylinder and is fitted with a piston. The piston is slidably mounted inside the straight cylinder. The end of the straight cylinder away from the guide hole is open, and a detachable cylinder cap is installed at the open end. A vent hole is opened in the middle of one side of the cylinder cap, and an adjustment control is provided inside the vent hole to change the size of the airflow channel. Multiple sets of cylinders are evenly arranged on the end cap surface. When the grinding jar rotates, the cylinders first obstruct, divert, and slow down the moving raw material and grinding media, preventing the material from directly impacting the inner wall of the end cap at a high speed, reducing scouring, impact, and wear, lowering the risk of end cap deformation, and extending service life. A hemispherical groove is provided at the front end of the cylinder, which can temporarily store, guide, and slow down the flow of materials, making the material movement smooth. At the same time, the weight of the material drives the cylinder and piston to retract, further reducing cylinder wear and extending the life of the overall buffer structure. Since the cylinder bears the main impact protection, the end cap does not need to be thickened to meet the strength and durability requirements, reducing the weight of the end cap and making loading, sealing, disassembly, and maintenance easier and more convenient.
[0006] Specifically, the control unit includes a rod, and a rod penetrating the vent is inserted into the vent. The diameter of the rod is smaller than the inner diameter of the vent. One end of the rod, located outside the straight cylinder, is connected to the cylinder cover via a support assembly. The other end of the rod, located inside the straight cylinder, is fitted with a tapered column that slides with the rod. The diameter of the tapered column gradually decreases towards the vent. When the end cover is below the grinding jar, the tapered column moves along the rod into the vent to narrow the airflow channel. When the end cover is above the grinding jar, the tapered column moves along the rod away from the vent to increase the airflow channel. The tapered column adapts to gravity and slides automatically, changing the vent flow area according to the rotation of the grinding jar: when the end cover is below, the orifice narrows, exhausting slowly, and the column retracts slowly to prevent impact and wear; when the end cover is above, the orifice expands, allowing for smooth air intake, and the column quickly extends and resets, ensuring continuous and reliable buffering.
[0007] Specifically, an end plate is installed at one end of the column rod inside the straight cylinder. External threads are machined on the outer half of the column rod away from the end plate. A first nut, which cooperates with the end plate to limit the range of motion of the conical column, is threaded onto the threaded portion of the column rod. The first nut is located on the side of the vent hole opposite to the conical column. By adjusting the position of the first nut on the column rod, the limiting stroke of the conical column and the minimum flow area of the vent hole can be changed, allowing the cylinder retraction speed to be adjusted as needed to adapt to different raw materials and grinding conditions.
[0008] Specifically, the support assembly includes a support plate. The support plate is located on the side of the cylinder cover opposite to the straight cylinder. Multiple connecting rods arranged equidistantly in a ring are installed between the support plate and the cylinder cover. A small hole is formed in the center of one side of the support plate. The end of the column rod away from the end plate passes through the small hole. Second nuts are provided on both sides of the small hole along the length of the column rod, and the second nuts are threaded to the externally threaded portion of the column rod. The support plate and connecting rods form a stable support structure, ensuring that the column rod and the tapered column remain concentric, without tilting or shaking, guaranteeing consistent opening and closing of the vent holes and stable and reliable long-term operation.
[0009] Specifically, a connecting ring is fitted onto one end of the straight cylinder near the cylinder cover, and the cylinder cover is connected to the connecting ring by multiple sets of bolts. The cylinder cover is fixed by the connecting ring bolts, making it easy to assemble and disassemble.
[0010] Specifically, the piston has a blind hole machined on the side facing the cylinder, and the end of the cylinder away from the hemispherical groove is installed in the blind hole. The cylinder and piston are assembled by blind hole insertion, which ensures a firm connection, high coaxiality, and prevents loosening.
[0011] Specifically, a base frame is provided on the lower side of the grinding jar. Both ends of the grinding jar are rotatably connected to the base frame via bearing seats. A geared motor is provided on one side of the grinding jar, and a motor frame is mounted on one side of the base frame. The geared motor is connected to the motor frame via bolts. A small pulley is mounted on the output shaft of the geared motor. Multiple large pulleys are fitted onto the outer surface of the grinding jar and fixed to it. The small pulleys are connected to the large pulleys via multiple transmission belts. The use of a geared motor and pulleys, combined with the support of the base frame and bearing seats, ensures stable rotation of the grinding jar, guaranteeing a stable grinding process and facilitating the preparation of ultrafine aluminum nitride powder with uniform particle size and high purity.
[0012] A method for preparing ultrafine aluminum nitride powder includes the following steps: S01, The aluminum source material and grinding media are loaded into the ball mill jar, and the end cap and frame are sealed to keep the ball mill jar in a sealed state; S02, start the geared motor to drive the ball mill jar to rotate. The material inside the ball mill jar is impacted and ground as the ball mill jar rotates. When the material moves to the end cover position, it is blocked and buffered by multiple cylinders on the end cover to avoid the material directly hitting the end cover at high speed. S03, During the ball milling process, according to the rotational posture of the ball mill jar, the conical column slides along the column rod under gravity, adaptively changing the air flow cross-sectional area of the vent hole, adjusting the air flow rate into and out of the straight cylinder, so that the piston drives the cylinder to extend and retract, maintaining the material buffering and grinding state stable. S04. After completing the ultrafine grinding, stop the reduction motor, wait for the ball mill jar to come to a complete stop, open the end cover and the inlet and outlet, and take out the obtained ultrafine aluminum nitride powder.
[0013] The beneficial effects of this invention are: When the ball mill jar rotates, the raw materials and grinding media inside the ball mill jar are blocked, diverted and buffered and slowed down by multiple evenly distributed cylinders before reaching the end cover. This prevents the material from directly impacting the inner wall of the end cover at a high speed, reduces the scouring, impact and wear of the material on the end cover, reduces the risk of end cover deformation, peeling and breakage, and extends the service life of the end cover.
[0014] When the raw materials and grinding media enter the hemispherical groove in the ball mill jar, the weight of the raw materials and grinding media in the ball mill jar forces the cylinder to drive the piston to slide in the straight cylinder, causing the cylinder to retract into the straight cylinder. At this time, the cylinder can temporarily store and guide the material, making the material move smoothly. At this time, the raw materials and grinding media in the ball mill jar will not cause excessive wear to the cylinder, extending the service life of the cylinder. Under long-term use conditions, the required design thickness of the end cap can be reduced, making the end cap lighter and easier to disassemble and assemble. Attached Figure Description
[0015] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of an ultrafine aluminum nitride powder preparation device according to the present invention; Figure 2 This is another perspective view of the apparatus for preparing ultrafine aluminum nitride powder according to the present invention; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 This is a schematic diagram of the assembly of the geared motor, end cap and ball mill jar in an ultrafine aluminum nitride powder preparation device of the present invention. Figure 5 This is a schematic diagram of the assembly of the cylinder, straight cylinder, support disk and end cap in the ultrafine aluminum nitride powder preparation device of the present invention; Figure 6This is a cross-sectional assembly diagram of the conical column, column rod, circular cover, straight cylinder and end cap in an ultrafine aluminum nitride powder preparation device of the present invention; Figure 7 This is an exploded structural diagram of the cylinder, piston, and straight cylinder in an ultrafine aluminum nitride powder preparation device of the present invention; Figure 8 This is an exploded structural diagram of the conical column, column rod, cylinder cover, and support disk in an ultrafine aluminum nitride powder preparation device of the present invention. In the diagram: 100, grinding jar; 101, bearing housing; 102, base frame; 103, frame; 200, end cap; 201, round opening; 300, straight cylinder; 301, cylinder cover; 3011, connecting ring; 3012, vent hole; 302, first nut; 303, column rod; 3031, second nut; 304, support plate; 3041, connecting rod; 3042, small hole; 305, cylinder; 3051, hemispherical groove; 306, tapered column; 3061, end plate; 307, piston; 3071, blind hole; 308, guide hole; 400, geared motor; 401, motor frame; 402, small pulley; 4021, transmission belt; 4022, large pulley. Detailed Implementation
[0016] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.
[0017] Please see Figures 1 to 8 This invention provides a technical solution: an ultrafine aluminum nitride powder preparation device, including a ball mill jar 100, a base frame 102 on the lower side of the ball mill jar 100, both ends of the ball mill jar 100 being rotatably connected to the base frame 102 via bearing seats 101, the bearing seats 101 and the base frame 102 jointly providing stable support for the ball mill jar 100, a reduction motor 400 on one side of the ball mill jar 100, and a motor frame 401 mounted on one side of the base frame 102, the reduction motor 400 being connected via screws... The bolt is connected to the motor frame 401. A small pulley 402 is installed on the output shaft of the geared motor 400. Multiple large pulleys 4022 are fitted on the outer surface of the grinding jar 100 and are fixed to the grinding jar 100. The small pulley 402 is connected to the large pulleys 4022 through multiple transmission belts 4021. When the geared motor 400 is working, it drives the small pulley 402 to rotate. The small pulley 402 drives the grinding jar 100 to rotate through the transmission belts 4021 and the large pulleys 4022.
[0018] The outer surface of the ball mill jar 100 is provided with an inlet and outlet. A frame 103 is provided on the outside of the inlet and outlet and is fixed to the ball mill jar 100. An end cap 200 is connected to the end of the frame 103 away from the ball mill jar 100 by multiple sets of bolts. Multiple round openings 201 are evenly provided on one side of the end cap 200. A straight cylinder 300 is installed in each of the multiple round openings 201. The round openings 201 provide space for the assembly of the straight cylinder 300 and the end cap 200.
[0019] A guide hole 308 is provided at the center of the side of the straight cylinder 300 facing the center area of the grinding jar 100. The part of the straight cylinder 300 away from the guide hole 308 is located on the side of the circular opening 201 away from the center area of the grinding jar 100. A cylinder 305 is inserted into the guide hole 308. The side of the cylinder 305 away from the straight cylinder 300 is machined with a hemispherical groove 3051 for temporarily storing the material in the grinding jar 100. After the material speed in the grinding jar 100 is slowed down by the obstruction of multiple cylinders 305, it moves to contact the end cover 200, so that the end of the cylinder 305 away from the hemispherical groove 3051 extends into the straight cylinder 300 and is installed in the blind hole 3071 machined on the side of the piston 307 facing the cylinder 305, thereby improving the speed of material movement. The stability of the connection between the cylinder 305 and the piston 307 is ensured. The piston 307 is slidably installed inside the straight cylinder 300. When the ball mill jar 100 is rotating, the aluminum source material and grinding media inside the ball mill jar 100 will be blocked, diverted, and buffered and decelerated by multiple cylinders 305 evenly distributed on the end cover 200 before moving to the end cover 200 area. This structure can prevent the material from directly impacting the inner wall of the end cover 200 at a high speed, reduce the continuous scouring, violent impact and repeated wear of the material on the end cover 200, reduce the risk of deformation, surface peeling or even local damage to the end cover 200 due to long-term stress, improve the structural stability of the end cover 200, and extend the overall service life of the end cover 200.
[0020] When the raw material and grinding media enter the hemispherical groove 3051 at the front end of the cylinder 305, the weight of the material itself creates downward pressure, pushing the cylinder 305 and piston 307 to slide smoothly inside the straight cylinder 300. This causes the cylinder 305 to slowly retract into the straight cylinder 300. During this process, the hemispherical groove 3051 and the cylinder 305 work together to temporarily store, guide, and stabilize the flow of the material, making the material's movement trajectory smoother and avoiding violent impacts and rigid collisions. This reduces excessive wear on the cylinder 305 caused by the raw material and grinding media, extending the service life of the cylinder 305. At the same time, because the impact load is dispersed and buffered, the end cap 200 does not need to use a thicker structure to meet the strength requirements, making the end cap 200 lighter overall, reducing the difficulty of disassembly and assembly, and improving the convenience of assembly and maintenance.
[0021] The end of the straight cylinder 300 away from the guide hole 308 is open. A detachable cylinder cover 301 is installed at the open end of the straight cylinder 300. A connecting ring 3011 is sleeved on the end of the straight cylinder 300 near the cylinder cover 301 and is fixed to the straight cylinder 300. The cylinder cover 301 is connected to the connecting ring 3011 by multiple sets of bolts, which facilitates the separation of the cylinder cover 301 from the straight cylinder 300 and facilitates the replacement of the cylinder 305 later.
[0022] A vent hole 3012 is provided in the middle of one side of the cylinder cover 301. A rod 303 is inserted through the vent hole 3012, and the diameter of the rod 303 is smaller than the inner diameter of the vent hole 3012. A support plate 304 is provided on the side of the cylinder cover 301 away from the straight cylinder 300. Multiple connecting rods 3041 arranged in a ring at equal intervals are installed between the support plate 304 and the cylinder cover 301. A small hole 3042 is provided in the middle of one side of the support plate 304. One end of the column rod 303 away from the end plate 3061 passes through a small hole 3042. A second nut 3031 is provided on both sides of the small hole 3042 along the length of the column rod 303. The second nut 3031 is threaded to the part of the column rod 303 where the external thread is machined. The second nut 3031 cooperates with the support plate 304 to restrict the relative position of the column rod 303 and the support plate 304, that is, the relative position of the column rod 303 and the cylinder cover 301 is restricted.
[0023] One end of the rod 303, located inside the straight cylinder 300, is fitted with a tapered column 306 that slides within the rod 303. The diameter of the tapered column 306 gradually decreases towards the vent 3012. With the end cap 200 positioned below the grinding jar 100, the tapered column 306 moves along the rod 303 into the vent 3012 to narrow the airflow channel, thus reducing the amount of air discharged from the straight cylinder 300 per unit time. At this time, the piston 307 moves at a slower speed within the straight cylinder 300, allowing the cylinder 305 to retract at a slower speed. The cylindrical column 305 moves at a relatively high speed inside the straight cylinder 300 to prevent excessive displacement of the raw materials and grinding media inside the grinding jar 100, thus further protecting the cylindrical column 305. With the end cap 200 on the upper side of the grinding jar 100, the conical column 306 moves along the column rod 303 to a distance away from the vent hole 3012 to increase the air circulation channel, allowing external air to quickly enter the straight cylinder 300 without affecting the extension of the cylindrical column 305 out of the straight cylinder 300, thereby realizing the dynamic adjustment of the extension and retraction state of the cylindrical column 305 with the rotation posture.
[0024] An end plate 3061 is installed at one end of the column rod 303 inside the straight cylinder 300. External threads are machined on half of the outer surface of the column rod 303 away from the end plate 3061. A first nut 302 is threaded to the part of the column rod 303 where the external threads are machined, which cooperates with the end plate 3061 to limit the range of motion of the tapered column 306. The first nut 302 is located on the side of the vent hole 3012 away from the tapered column 306. Adjusting the position of the first nut 302 on the column rod 303 increases or decreases the distance between the first nut 302 and the end plate 3061. Consequently, when the end cover 200 is located below the ball mill jar 100, the length of the conical column 306 passing through the vent hole 3012 under the restriction of the first nut 302 increases or decreases, thereby changing the minimum airflow channel formed by the vent hole 3012 and the conical column 306. This allows for adjustment of the size of the airflow channel formed by the vent hole 3012 and the conical column 306 as needed, meaning the speed at which the cylinder 305 retracts into the straight cylinder 300 is adjustable.
[0025] A method for preparing ultrafine aluminum nitride powder: First, aluminum source material and grinding media are loaded into a ball mill jar 100. The end cover 200 and frame 103 are then sealed to keep the ball mill jar 100 in a sealed state. Then, the geared motor 400 is started to drive the ball mill jar 100 to rotate. The material inside the ball mill jar 100 is impact-ground as the ball mill jar 100 rotates. When the material moves to the end cover 200, it is blocked and buffered by multiple cylinders 305 on the end cover 200, preventing the material from directly impacting the end cover 200 at high speed. During the ball milling process, according to the rotational posture of the ball mill jar 100, the conical column 306 slides along the column rod 303 under gravity, adaptively changing the air flow cross-sectional area of the vent 3012, adjusting the air flow rate into and out of the straight cylinder 300, so that the piston 307 drives the cylinder 305 to extend and retract, maintaining the material buffering and grinding state stability. After the ultrafine grinding is completed, the reduction motor 400 is stopped, and after the ball mill jar 100 is completely stationary, the end cover 200 and the inlet and outlet are opened to take out the obtained ultrafine aluminum nitride powder.
[0026] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. An apparatus for preparing ultrafine aluminum nitride powder, comprising a ball mill jar (100), characterized in that: The ball mill jar (100) has an inlet and outlet port on its outer surface. A frame (103) is fixed to the ball mill jar (100) on the outside of the inlet and outlet port. An end cap (200) is connected to the end of the frame (103) away from the ball mill jar (100) by multiple sets of bolts. Multiple circular openings (201) are evenly distributed on one side of the end cap (200). A straight cylinder (300) is installed inside each of the circular openings (201). A guide hole (308) is provided in the center of the side of the straight cylinder (300) facing the center area of the ball mill jar (100). The part of the straight cylinder (300) away from the guide hole (308) is located on the side of the circular openings (201) away from the center area of the ball mill jar (100). A cylinder (305) is inserted into the guide hole (308). The cylinder (305) is located away from the straight cylinder (300). One side of the ball mill jar (100) is machined with a hemispherical groove (3051) for temporarily storing the material in the ball mill jar (100). After the material in the ball mill jar (100) is slowed down by the obstruction of the multiple cylinders (305), it moves to contact the end cap (200). The end of the cylinder (305) away from the hemispherical groove (3051) extends into the straight cylinder (300) and is equipped with a piston (307). The piston (307) is slidably installed in the straight cylinder (300). The end of the straight cylinder (300) away from the guide hole (308) is open. A detachable cylinder cover (301) is installed at the open end of the straight cylinder (300). A vent hole (3012) is provided in the middle of one side of the cylinder cover (301). An adjustment control is provided in the vent hole (3012) for changing the size of the air flow channel of the vent hole (3012).
2. The apparatus for preparing ultrafine aluminum nitride powder according to claim 1, characterized in that: The control unit includes a rod (303), and a rod (303) is inserted into the vent (3012) through the vent (3012). The diameter of the rod (303) is smaller than the inner diameter of the vent (3012). One end of the rod (303) located outside the straight cylinder (300) is connected to the cylinder cover (301) through a support assembly. The other end of the rod (303) located inside the straight cylinder (300) is fitted with a tapered column (306) that slides with the rod (303). The diameter of the conical column (306) gradually decreases towards the vent (3012). When the end cap (200) is below the grinding jar (100), the conical column (306) moves along the column (303) into the vent (3012) to narrow the airflow channel. When the end cap (200) is above the grinding jar (100), the conical column (306) moves along the column (303) away from the vent (3012) to increase the airflow channel.
3. The apparatus for preparing ultrafine aluminum nitride powder according to claim 2, characterized in that: The end of the column (303) located inside the straight cylinder (300) is equipped with an end plate (3061). The outer surface of the column (303) is machined with external threads in half of the area away from the end plate (3061). The part of the column (303) with external threads is threadedly connected to a first nut (302) that cooperates with the end plate (3061) to limit the range of motion of the tapered column (306). The first nut (302) is located on the side of the vent (3012) away from the tapered column (306).
4. The apparatus for preparing ultrafine aluminum nitride powder according to claim 3, characterized in that: The support assembly includes a support plate (304). The support plate (304) is provided on the side of the cylinder cover (301) away from the straight cylinder (300). A plurality of connecting rods (3041) arranged in a ring at equal intervals are installed between the support plate (304) and the cylinder cover (301). A small hole (3042) is provided in the middle of one side of the support plate (304). The end of the column rod (303) away from the end plate (3061) passes through the small hole (3042). A second nut (3031) is provided on both sides of the small hole (3042) along the length direction of the column rod (303). The second nut (3031) is threaded to the part of the column rod (303) where the external thread is machined.
5. The apparatus for preparing ultrafine aluminum nitride powder according to claim 4, characterized in that: The straight cylinder (300) is fitted with a connecting ring (3011) near the end of the cylinder cover (301) and is fixed to the straight cylinder (300). The cylinder cover (301) is connected to the connecting ring (3011) by multiple sets of bolts.
6. The apparatus for preparing ultrafine aluminum nitride powder according to claim 4, characterized in that: The piston (307) has a blind hole (3071) on the side facing the cylinder (305), and the end of the cylinder (305) away from the hemispherical groove (3051) is installed in the blind hole (3071).
7. The apparatus for preparing ultrafine aluminum nitride powder according to claim 4, characterized in that: The ball mill jar (100) is provided with a base frame (102) on its lower side. Both ends of the ball mill jar (100) are rotatably connected to the base frame (102) through bearing seats (101). A geared motor (400) is provided on one side of the ball mill jar (100). A motor frame (401) is installed on one side of the base frame (102). The geared motor (400) is connected to the motor frame (401) by bolts. A small pulley (402) is installed on the output shaft of the geared motor (400). Multiple large pulleys (4022) are fitted on the outer surface of the ball mill jar (100) and are fixed to the ball mill jar (100). The small pulleys (402) are connected to the large pulleys (4022) through multiple transmission belts (4021).
8. A method for preparing ultrafine aluminum nitride powder according to any one of claims 1-7, characterized in that... Includes the following steps: S01, the aluminum source material and grinding media are loaded into the ball mill jar (100), and the end cap (200) and frame (103) are closed to make the ball mill jar (100) in a sealed state; S02, start the geared motor (400) to drive the ball mill (100) to rotate. The material inside the ball mill (100) is impacted and ground as the ball mill (100) rotates. When the material moves to the end cover (200), it is blocked and buffered by multiple cylinders (305) on the end cover (200) to avoid the material directly impacting the end cover (200) at high speed. S03, during the ball milling process, according to the rotational posture of the ball milling jar (100), the conical column (306) slides along the column rod (303) under gravity, adaptively changing the air flow cross-sectional area of the vent (3012), adjusting the flow rate of air entering and exiting the straight cylinder (300), so that the piston (307) drives the cylinder (305) to extend and retract, maintaining the material buffering and grinding state stability; S04. After completing the ultrafine grinding, stop the geared motor (400), wait for the ball mill jar (100) to come to a complete stop, open the end cover (200) and the inlet and outlet, and take out the obtained ultrafine aluminum nitride powder.