Rapid preparation method of Al3BC / Al composite powder

Abstract

The invention discloses a rapid preparation method of Al3BC / Al composite powder, belongs to the technical field of MAX phase reinforced aluminum-based composite material preparation, and particularly relates to the rapid preparation method of the Al3BC / Al composite powder. The invention aims to overcome the defects of long process period, high cost and difficulty in impurity control in the prior art. The method comprises the following steps: uniformly mixing raw materials through ball milling; and the mixed powder is loaded into a carbon carrier, the carbon carrier is connected into an electrode of Joule heating equipment to form a loop, the carbon carrier is vacuumized to a low-vacuum-degree state, protective gas is inflated, an equipment power source is started, parameters are set, voltage is applied for heating, after program operation is finished, the carbon carrier is cooled to the room temperature, and the Al3BC / Al composite powder can be obtained. The method has the advantages that rapid temperature rising-heating-cooling is achieved through the Joule heating technology, operation is simple and the like, and composite powder is rapidly prepared; and the obtained composite powder is high in purity. The method is simple and convenient to operate, short in technological process time consumption and low in cost, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of MAX phase reinforced aluminum matrix composite material preparation technology, specifically relating to a rapid preparation method of Al3BC / Al composite powder. Background Technology

[0002] Max-phase ceramics, due to their unique layered crystal structure, combine the high hardness and high melting point of ceramics with the excellent thermal and electrical conductivity and ease of processing of metals, making them one of the ideal candidates for reinforcements in high-performance composite materials. Among them, Al3BC, as a typical ternary MAX-phase compound, has a density of only 2.83 g / cm³. 3 Its hardness is far lower than that of traditional ceramic reinforcements, giving it a lightweight advantage; at the same time, its hardness is as high as 14GPa, and it has excellent chemical and thermal stability. It can maintain stable performance under extreme conditions such as high temperature and corrosion, making it a highly promising reinforcing phase for aluminum-based composite materials.

[0003] Introducing Al3BC into an aluminum matrix to prepare Al3BC / Al composites can significantly improve the core mechanical properties of aluminum and aluminum alloys, such as strength, hardness, and wear resistance. These composites are widely used in aerospace, new energy vehicles, and high-end equipment manufacturing, where lightweighting and high performance are critical requirements. Currently, the core of Al3BC / Al composite preparation lies in the acquisition and compounding of Al3BC reinforcements. The mainstream technical routes are divided into two main categories: external reinforcement methods and in-situ self-generated reinforcement methods. Both face significant technical bottlenecks in practical applications. Methods for preparing Al3BC powder mainly include self-propagating high-temperature synthesis and solid-state reaction / sintering methods. The self-propagating high-temperature synthesis method involves ball milling raw materials such as aluminum particles, amorphous boron, and graphite, followed by reaction at 500–1000℃ for 3 hours. This method has a long preparation cycle and forms complex impurity phases (such as Al4C3, AlN, and Al8B4C7). The solid-state reaction / sintering method involves reacting at 500°C for 24 hours followed by sintering at 600°C for 1 hour. While this achieves Al3BC powder synthesis at low temperatures, the long preparation cycle and time consumption result in higher energy consumption. Furthermore, the extended preparation time also leads to the formation of more impurities, such as AlB2, γ-Al2O3, and MgAl2O. CN116730723A, reporting "An Al3BC Ceramic Material and Its Preparation Method and Application," employs a three-stage sintering method: sintering at 550–650°C for 1–2 hours, at 700–800°C for 2–5 hours, and at 900–1000°C for 1–3 hours. While this method yields Al3BC powder, it still retains a certain proportion of raw material Al and B4C powder impurities and requires a long sintering time to ensure complete reaction. The long preparation cycle and high cost limit its application. Moreover, the introduction of impurities reduces product purity, necessitating subsequent purification processes, which further increases the preparation cycle and cost. In-situ synthesis of Al3BC / Al composites typically requires a liquid-solid reaction, which is more difficult to control and prone to generating brittle impurity phases such as Al4C3, AlB2, and Al8B4C7, severely reducing mechanical properties. CN115921849A reports "A spherical Al3BC / Al composite powder and its preparation method," which uses spray granulation combined with low-temperature + high-temperature calcination to synthesize Al3BC / Al composite powder. This method involves multiple steps and a long preparation cycle (approximately 3-36 hours).

[0004] Current preparation processes for Al3BC / Al composite powders generally suffer from common drawbacks, including long preparation cycles, high production costs, and difficulty in controlling impurity phases. Furthermore, existing processes struggle to balance phase purity, production efficiency, and cost control, failing to meet the large-scale application requirements of Al3BC / Al composites in high-end fields such as aerospace and new energy. Therefore, developing a rapid, efficient, low-impurity, and cost-controllable method for preparing Al3BC / Al composite powders has become a crucial technological challenge urgently needing breakthroughs in this field. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing processes, such as long cycle times, high costs, and difficulty in controlling impurities, by providing a rapid preparation method for Al3BC / Al composite powder. This invention utilizes rapid heating / cooling and multi-stage thermal cycling to suppress side reactions, shorten the cycle time, and improve purity, completing the preparation within minutes, making it suitable for large-scale production.

[0006] This invention proposes a rapid preparation method for Al3BC / Al composite powder, which is completed according to the following steps:

[0007] 1. Weigh out aluminum powder, boron powder and carbon source according to the ratio, and ball mill and mix them evenly;

[0008] 2. Load the mixed powder into a carbon carrier and connect it to the electrode of a Joule heating device to form a circuit; evacuate to a low vacuum and fill with protective gas to the set pressure; set the target temperature, heating rate, and holding time, rapidly cool down to 900~1000℃ and hold for 30~60s to complete one thermal cycle; repeat the cycle 2~4 times, cool to room temperature, and obtain Al3BC / Al composite powder.

[0009] Beneficial effects of this invention:

[0010] This invention utilizes the rapid heating and cooling characteristics of Joule heating to achieve efficient control of the reaction process, thereby significantly shortening the preparation cycle. Compared to the traditional electric furnace heating process that requires several hours, this invention can complete the preparation of Al3BC / Al composite powder in minutes. Simultaneously, this method reduces preparation costs while effectively controlling the formation of impurities such as Al4C3 and Al8B4C7, demonstrating significant efficiency and quality advantages.

[0011] This invention uses aluminum powder, boron powder, and a carbon source as raw materials to prepare Al3BC / Al composite powder. It utilizes Joule heating technology to achieve rapid heating and reaction, and employs simple and easy-to-operate equipment, enabling the rapid preparation of Al3BC / Al composite powder. By ball milling and mixing the aluminum powder, boron powder, and carbon source, uniform contact is ensured, allowing the reaction to proceed fully. The rapid heating / cooling and uniform temperature characteristics of Joule heating technology are crucial for the rapid preparation of Al3BC / Al composite powder. The Al3BC / Al composite powder obtained by this invention mainly consists of diffraction peaks of Al3BC and Al phases, without the detection of harmful phases such as Al4C3 and Al8B4C7. The powder has high purity, and Al3BC grows outward from the surface of the aluminum powder, effectively achieving uniform distribution of Al3BC. Furthermore, the operation is simple, the process is time-efficient, and the cost is low, enabling the rapid preparation of Al3BC / Al composite powder. Attached Figure Description

[0012] Figure 1This is a scan image of the Al3BC / Al composite powder obtained in Example 1.

[0013] Figure 2 The image shows the XRD pattern of the Al3BC / Al composite powder obtained in Example 1.

[0014] Figure 3 This is a scan image of the Al3BC / Al composite powder obtained in Example 2.

[0015] Figure 4 This is a scan image of the Al3BC / Al composite powder obtained in Example 3. Detailed Implementation

[0016] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0017] Specific Implementation Method 1: This implementation method for the rapid preparation of Al3BC / Al composite powder is completed according to the following steps:

[0018] 1. Weigh out aluminum powder, boron powder and carbon source according to the ratio, and ball mill and mix them evenly;

[0019] 2. Load the mixed powder into a carbon carrier and connect it to the electrode of a Joule heating device to form a circuit; evacuate to a low vacuum and fill with protective gas to the set pressure; set the target temperature, heating rate, and holding time, rapidly cool down to 900~1000℃ and hold for 30~60s to complete one thermal cycle; repeat the cycle 2~4 times, cool to room temperature, and obtain Al3BC / Al composite powder.

[0020] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the molar ratio of aluminum powder:boron powder:carbon source in step one is (4~8):1:1. Everything else is the same as in Specific Implementation Method One.

[0021] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the aluminum powder used in step one is industrial pure aluminum powder with an average particle size of 1μm~5μm. Everything else is the same as in Specific Implementation Method One.

[0022] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the boron powder in step one is selected from one or more of industrial boron powder, high-purity boron powder, and amorphous boron powder, with an average particle size of 0.5μm~2μm. Everything else is the same as in Specific Implementation Method One.

[0023] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that the carbon source in step one is selected from one or both of graphene and carbon nanotubes. Everything else is the same as in Specific Implementation Method One.

[0024] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that: in step one, the ball milling speed is 150r / min to 300r / min, the ball milling time is 2h to 6h, and the ball-to-material ratio is 3:1 to 6:1.

[0025] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that: in step two, the protective gas is one or both of nitrogen and argon, and the protective gas pressure is 10. 2 ~10 4 Pa. Everything else is the same as in Specific Implementation Method 1.

[0026] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in that: in step two, the target temperature is 1000~1200℃, the heating rate is 50~100℃ / s, and the holding time in the high-temperature section is 30~60s. Everything else is the same as in Specific Implementation Method One.

[0027] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that the number of thermal cycles in step two is 2 to 4, and the temperature difference between adjacent cycles is 100 to 200°C. Everything else is the same as in Specific Implementation Method One.

[0028] In this embodiment, the first cycle rapidly activates the interface to form Al3BC crystal nuclei; subsequent cycles directionally grow Al3BC on the existing crystal nuclei instead of generating new impurity phases; the temperature difference between cycles (100-200℃) generates thermal shock, which promotes atomic diffusion but does not trigger side reactions.

[0029] The beneficial effects of the present invention are verified by the following embodiments:

[0030] Example 1:

[0031] 1. Weigh aluminum powder with an average particle size of 1μm, boron powder with an average particle size of 2μm and carbon nanotubes in a ratio of 4:1:1, and then mix them evenly by ball milling at a speed of 300r / min for 2h. The ball milling ratio is 4:1.

[0032] 2. The mixed powder is loaded into a carbon support, and the carbon support is connected to the electrode of the Joule heating device to form a circuit. Then, the device is evacuated to a low vacuum state, and nitrogen gas is introduced into the sample chamber until the pressure reaches 10. 2 Pa, then turn on the power of the device, set the temperature to 1000℃, the heating rate to 50℃ / s, and the holding time to 60s, then quickly cool down to 900℃ and hold for 60s. After completing one thermal cycle, repeat 3 times. After the program runs out and cools to room temperature, Al3BC / Al composite powder can be obtained; the carbon carrier is graphite paper.

[0033] Example 2:

[0034] 1. Weigh aluminum powder with an average particle size of 5μm, boron powder with an average particle size of 0.5μm and carbon nanotubes in a ratio of 8:1:1, and then mix them evenly by ball milling at a speed of 300r / min for 3h and a ball-to-material ratio of 3:1.

[0035] 2. The mixed powder is loaded into a carbon support, and the carbon support is connected to the electrode of the Joule heating device to form a circuit. Then, the device is evacuated to a low vacuum state, and nitrogen gas is introduced into the sample chamber until the pressure reaches 10. 4 Pa, then turn on the power of the device, set the temperature to 1200℃, the heating rate to 100℃ / s, and the holding time to 30s, then quickly cool down to 1000℃ and hold for 30s. After completing one thermal cycle, repeat twice. After the program runs out and cools to room temperature, Al3BC / Al composite powder can be obtained; the carbon carrier is graphite paper.

[0036] Example 3:

[0037] 1. Weigh aluminum powder with an average particle size of 3μm, boron powder with an average particle size of 1μm and graphene according to a ratio of 6:1:1, and then mix them evenly by ball milling. The ball milling speed is 150r / min, the ball milling time is 6h, and the ball-to-material ratio is 6:1.

[0038] 2. The mixed powder is loaded into a carbon support, and the carbon support is connected to the electrode of the Joule heating device to form a circuit. Then, the device is evacuated to a low vacuum state, and nitrogen gas is introduced into the sample chamber until the pressure reaches 10. 2 Pa, then turn on the power of the device, set the temperature to 1000℃, the heating rate to 80℃ / s, and the holding time to 50s, then quickly cool down to 950℃ and hold for 30s. After completing one thermal cycle, repeat 4 times. After the program runs out and cools to room temperature, Al3BC / Al composite powder can be obtained; the carbon carrier is graphite paper.

[0039] Example 4:

[0040] 1. Weigh aluminum powder with an average particle size of 1μm, boron powder with an average particle size of 2μm and graphene in a ratio of 5:1:1, and then mix them evenly by ball milling. The ball milling speed is 200r / min, the ball milling time is 5h, and the ball-to-material ratio is 4:1.

[0041] 2. The mixed powder is loaded into a carbon support, and the carbon support is connected to the electrode of the Joule heating device to form a circuit. Then, the device is evacuated to a low vacuum state, and nitrogen gas is introduced into the sample chamber until the pressure reaches 10. 3Pa, then turn on the power of the device, set the temperature to 1100℃, the heating rate to 70℃ / s, and the holding time to 50s, then quickly cool down to 1000℃ and hold for 30s. After completing one thermal cycle, repeat 3 times. After the program runs out and cools to room temperature, Al3BC / Al composite powder can be obtained; the carbon carrier is graphite paper.

[0042] The Al3BC / Al composite powder obtained by this invention has high purity and a near-spherical shape, with Al3BC grown on the surface of aluminum powder. The morphology of the Al3BC / Al composite powder obtained in Example 1 is as follows. Figure 1 and Figure 2 As shown. From Figure 1 As can be seen, the composite powder is nearly spherical and has a regular shape; from Figure 2 As can be seen, the composite powder mainly consists of diffraction peaks of Al3BC and Al phases, indicating high powder purity. The morphologies of the Al3BC / Al composite powders obtained in Examples 2 and 3 are shown below. Figure 3 and Figure 4 As shown. From Figure 3 and Figure 4 As can be seen, Al3BC on the surface of aluminum powder has two forms: short rod-shaped and plate-shaped.

Claims

1. A rapid preparation method for Al3BC / Al composite powder, characterized in that... The rapid preparation method of Al3BC / Al composite powder is completed according to the following steps:

1. Weigh out aluminum powder, boron powder and carbon source according to the ratio, and ball mill and mix them evenly; 2. Load the mixed powder into a carbon carrier and connect it to the electrode of a Joule heating device to form a circuit; evacuate to a low vacuum and fill with protective gas to the set pressure; set the target temperature, heating rate, and holding time, rapidly cool down to 900~1000℃ and hold for 30~60s to complete one thermal cycle; repeat the cycle 2~4 times, cool to room temperature, and obtain Al3BC / Al composite powder.

2. The rapid preparation method of Al3BC / Al composite powder according to claim 1, characterized in that... In step one, the molar ratio of aluminum powder:boron powder:carbon source is (4~8):1:

1.

3. The rapid preparation method of Al3BC / Al composite powder according to claim 1, characterized in that... The aluminum powder used in step one is industrial pure aluminum powder with an average particle size of 1μm to 5μm.

4. The rapid preparation method of Al3BC / Al composite powder according to claim 1, characterized in that... In step one, the boron powder is selected from one or more of industrial boron powder, high-purity boron powder, and amorphous boron powder, with an average particle size of 0.5μm to 2μm.

5. The rapid preparation method of Al3BC / Al composite powder according to claim 1, characterized in that... In step one, the carbon source is selected from one or both of graphene and carbon nanotubes.

6. The rapid preparation method of Al3BC / Al composite powder according to claim 1, characterized in that... In step one, the ball milling speed is 150 r / min to 300 r / min, the ball milling time is 2 h to 6 h, and the ball-to-material ratio is 3:1 to 6:

1.

7. The rapid preparation method of Al3BC / Al composite powder according to claim 1, characterized in that... In step two, the protective gas is one or both of nitrogen and argon, and the protective gas pressure is 10. 2 ~10 4 Pa.

8. The rapid preparation method of Al3BC / Al composite powder according to claim 1, characterized in that... In step two, the target temperature is 1000~1200℃, the heating rate is 50~100℃ / s, and the holding time is 30~60s.

9. A rapid preparation method for Al3BC / Al composite powder according to claim 1, characterized in that... In step two, the number of thermal cycles is 2 to 4, and the temperature difference between adjacent cycles is 100 to 200℃.

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