Method for simultaneously preparing micron aluminum powder and nano aluminum powder

Abstract

The invention relates to a method for simultaneously preparing micron aluminum powder and nano aluminum powder, and belongs to the technical field of nano metal powder. The method comprises the following steps: forming working gas into plasma by using a radio frequency induction plasma method, and controlling process parameters of the radio frequency induction plasma method so as to regulate and control the energy of the plasma; the precursor raw material aluminum powder with the set average particle size is heated through plasmas, so that the precursor raw material aluminum powder is converted into a gaseous state and a molten state; and the precursor raw material aluminum powder in the gaseous state and the molten state is cooled, so that the precursor raw material aluminum powder in the gaseous state forms nano aluminum powder, the precursor raw material aluminum powder in the molten state forms micron aluminum powder, and the micron aluminum powder and the nano aluminum powder are obtained at the same time. According to the embodiment of the invention, the preparation of the micron aluminum powder and the nano aluminum powder is realized at the same time by adjusting the energy of the plasma and the particle size of the precursor raw material aluminum powder, and the proportion of the micron aluminum powder and the nano aluminum powder is adjustable, so that the requirements of actual use are met.

Description

Technical Field

[0001] The present application relates to the technical field of nano-metal powders, and in particular to a method for simultaneously preparing micron aluminum powder and nano aluminum powder. Background Art

[0002] With the development of additive manufacturing technology, it is possible to manufacture high-performance complex structural parts, which is very difficult or even impossible to achieve in traditional manufacturing processes. By stacking materials layer by layer, additive manufacturing technology can produce objects with complex internal structures, such as honeycomb structures, microporous materials, etc. These structures are widely used in aerospace, medical equipment and other fields. Not only that, additive manufacturing technology can also provide better performance and functions. However, additive manufacturing technology has high requirements for raw materials, that is, micron-level metal powders, requiring them to have high sphericity, good fluidity, and low impurity content. Therefore, the development of high-purity spherical micron-level metal powder raw material preparation technology has positive significance for the application of additive manufacturing technology.

[0003] Nano metal powder has unique mechanical and physical properties because it has a large surface area to volume ratio, high surface energy and many unique characteristics that other large-sized metal powders do not have. By adding some nano metal powders and integrating the use of nano metal powders and micron metal powders, the performance of materials prepared by powder metallurgy and additive manufacturing can be greatly improved. Metal aluminum is widely used in various powder metallurgy and additive manufacturing processes due to its high strength and low density. It is an ideal choice for application industries such as aerospace, electronic information and automobiles that require strong and lightweight components. The development of a preparation technology that can prepare high-quality, high-purity spherical micron and nano-level aluminum powders is a problem that needs to be solved at present. The preparation process of micron-level aluminum powder is relatively simple, but the preparation of nano-level metal powder is more difficult. The current methods for preparing nano aluminum powder mainly include physical methods and chemical methods. The preparation of nano aluminum powder by chemical method currently has problems such as difficult size control, high cost, low preparation purity, and easy agglomeration and oxidation of the prepared nano powder, and it still remains in the laboratory stage. The principle of physical method for preparing nano aluminum powder is mainly evaporation-condensation, and the main technical methods include wire explosion method, arc discharge method and plasma method. Summary of the invention

[0004] The present application provides a method for simultaneously preparing micron aluminum powder and nano aluminum powder to solve the following technical problem: how to achieve the simultaneous preparation of micron aluminum powder and nano aluminum powder.

[0005] In a first aspect, an embodiment of the present application provides a method for simultaneously preparing micron aluminum powder and nano aluminum powder, the method comprising:

[0006] Using a radio frequency induction plasma method to form a plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to adjust the energy of the plasma;

[0007] Using the plasma to heat the precursor raw aluminum powder having a set average particle size, so that the precursor raw aluminum powder is converted into a gaseous state and a molten state;

[0008] The precursor raw aluminum powder in gaseous state and molten state is cooled to make the precursor raw aluminum powder in gaseous state form nano aluminum powder and the precursor raw aluminum powder in molten state form micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

[0009] Optionally, the set average particle size is 10 μm to 60 μm.

[0010] Optionally, the process parameters of the radio frequency induction plasma method include: the frequency of the radio frequency power supply, the power of the radio frequency power supply and the pressure of the reaction chamber of the radio frequency induction device.

[0011] Optionally, the frequency of the radio frequency power source is 2 MHz to 10 MHz; and / or,

[0012] The power of the radio frequency power supply is 10kW to 60kW; and / or,

[0013] The pressure of the reaction chamber of the radio frequency induction device is 0.05MPa-0.3MPa.

[0014] Optionally, the reaction chamber is made of quartz, and a mixed gas of high-purity argon and high-purity hydrogen is used as the protective gas for the quartz, the flow rate of the high-purity argon is 20L / min to 100L / min, and the flow rate of the high-purity hydrogen is 5L / min to 20L / min.

[0015] Optionally, the flow rate of the working gas is 10L / min to 50L / min.

[0016] Optionally, the flow rate of the precursor raw material aluminum powder is 5 g / min to 50 g / min; and / or,

[0017] The flow rate of the carrier gas of the precursor raw material aluminum powder is 2L / min to 10L / min.

[0018] Optionally, the cooling is performed by air cooling, and the flow rate of the gas used in the air cooling is 200L / min to 1000L / min.

[0019] Optionally, the precursor raw aluminum powder in gaseous state and molten state is cooled so that the precursor raw aluminum powder in gaseous state forms nano aluminum powder and the precursor raw aluminum powder in molten state forms micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time, and then further comprises:

[0020] The micron aluminum powder and the nano aluminum powder are passivated by using oxygen so that an oxide layer is formed on the surface of the micron aluminum powder and the surface of the nano aluminum powder to obtain a micron aluminum powder product and a nano aluminum powder product; wherein the flow rate of the oxygen is 0.02L / min to 0.1L / min.

[0021] Optionally, the weight ratio of the micron aluminum powder to the nano aluminum powder is 1:(1-9);

[0022] The shapes of the micron aluminum powder and the nano aluminum powder include at least one of the following: spherical, nearly spherical, and quasi-spherical;

[0023] The average particle size of the micron aluminum powder is 5 μm to 60 μm, and the average particle size of the nano aluminum powder is 50 nm to 300 nm.

[0024] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0025] The method for simultaneously preparing micron aluminum powder and nano aluminum powder provided in an embodiment of the present application comprises: using a radio frequency induction plasma method to form a plasma from a working gas, and controlling the process parameters of the radio frequency induction plasma method to regulate the energy of the plasma; using the plasma to heat a precursor raw aluminum powder with a set average particle size to convert the precursor raw aluminum powder into a gaseous state and a molten state; cooling the precursor raw aluminum powder in a gaseous state and a molten state to form a nano aluminum powder from the precursor raw aluminum powder in a gaseous state, and to form a micron aluminum powder from the precursor raw aluminum powder in a molten state, so as to obtain micron aluminum powder and nano aluminum powder at the same time. The radio frequency induction plasma method is used to ionize the working gas through a high frequency electric field to form a plasma. The plasma has high temperature and high energy. The process parameters of the radio frequency induction plasma method are controlled to regulate the energy of the plasma, so that the plasma heats the precursor raw material aluminum powder with a set average particle size, which can convert the precursor raw material aluminum powder into a gaseous state and a molten state. The synergistic effect of the plasma energy and the set average particle size causes the surface part of the precursor raw material aluminum powder particles to evaporate into a gaseous state, and the internal melting into a molten state; during the cooling process of the precursor raw material aluminum powder in a gaseous state, the gaseous aluminum atoms or molecules will gather and condense when the temperature drops rapidly. Since they are in a dispersed gaseous state, they can form a smaller size of nano aluminum powder during cooling; during the cooling of the precursor raw material aluminum powder in a molten state, since the material in the molten state has a certain fluidity, it will tend to form a sphere with the smallest surface area under the promotion of surface tension, and finally become a micron powder after cooling and solidification. The evaporated part of the precursor raw material aluminum powder is cooled to form a nano powder, and the molten precursor raw material aluminum powder is cooled to form a micron powder. Therefore, the simultaneous preparation of micron aluminum powder and nano aluminum powder is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 A schematic flow chart of a method for simultaneously preparing micron aluminum powder and nano aluminum powder provided in an embodiment of the present application;

[0029] Figure 2A schematic structural diagram of a system for simultaneously preparing micron aluminum powder and nano aluminum powder provided in an embodiment of the present application; wherein, 1 - precursor aluminum powder raw material; 2 - feeding system; 3 - working gas inlet; 4 - protective gas inlet; 5 - cooling water inlet; 6 - induction coil; 7 - cooling gas inlet; 8 - cooling water outlet; 9 - exhaust gas emission system; 10 - micron-grade aluminum powder collection chamber; 11 - nano-grade aluminum powder collection chamber; 12 - powder separation filter; 13 - passivation gas inlet. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0032] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0033] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0034] In a first aspect, the present invention provides a method for simultaneously preparing micron aluminum powder and nano aluminum powder. Figure 1 A schematic diagram of a method for simultaneously preparing micron aluminum powder and nano aluminum powder provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0035] S1. Using a radio frequency induction plasma method to form a plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to adjust the energy of the plasma;

[0036] In some embodiments, the process parameters of the RF induction plasma method include: the frequency of the RF power supply, the power of the RF power supply, and the pressure of the reaction chamber of the RF induction device.

[0037] In some embodiments, the frequency of the radio frequency power source is 2 MHz to 10 MHz; and / or,

[0038] The power of the radio frequency power supply is 10kW to 60kW; and / or,

[0039] The pressure of the reaction chamber of the radio frequency induction device is 0.05MPa-0.3MPa.

[0040] In the embodiment of the present application, the radio frequency induction plasma method is a technology for preparing spherical powders. It generates plasma through radio frequency induction, heats the powder material to a high temperature, melts it, evaporates it, and forms a sphere under the action of surface tension, and finally cools and solidifies it to obtain a spherical powder. Plasma has an extremely high energy density, and the temperature in the central area can reach 10 4 K~10 5 K, causing the metal to melt and evaporate instantly. The metal vapor collides violently with the cooling gas and is rapidly cooled into nanopowder. The main advantages of the RF induction plasma method are as follows: (1) Efficient energy conversion. The plasma has an extremely high volume energy density. During the heating process of the precursor metal, the energy utilization rate is high; (2) The process parameters can be flexibly adjusted to achieve the controllable preparation of single nanopowders or the simultaneous controllable preparation of micron and nanopowders; (3) It can be widely used in the synthesis of various metal powders with low requirements for raw materials; (4) The average particle size distribution of the product is consistent; (5) The nanometal powder produced by the RF induction plasma method has a low degree of oxidation and high purity. It shows high activity in chemical applications, but also shows good stability during storage.

[0041] The process parameters of the RF induction plasma method are controlled to regulate the energy of the plasma. The process parameters of the RF induction plasma method include: the frequency of the RF power supply, the power of the RF power supply, and the pressure of the reaction chamber of the RF induction device. The change of frequency will affect the energy distribution of the plasma. At lower frequencies, according to the skin effect, the frequency will affect the heating area of ​​the plasma. The power directly determines the energy input to the plasma. The greater the power, the more energy the electrons in the plasma obtain, and the higher the electron temperature and movement speed. The power is also related to the heating area and the energy required for the raw material. The reaction chamber pressure affects the collision frequency of the particles and the plasma density. The frequency of the RF power supply can be 2MHz to 10MHz, which can make the coupling effect between the RF power supply and the plasma relatively good, and can provide a heating area with a suitable width according to the skin effect, and is easy to ignite and match the subsequent feeding flow. The power of the RF power supply can be 10kW to 60kW, which can provide enough energy for the plasma to maintain the high temperature state of the plasma, and can better match the heating area at different frequencies. Combined with the frequency of the RF power supply, a better coupling effect can be achieved, and the appropriate power can make the energy transfer between the plasma and the RF electric field more efficient, reducing energy reflection and other loss phenomena. The pressure of the reaction chamber of the radio frequency induction device can be 0.05MPa to 0.3MPa, which can effectively adjust the powder flow rate. As the pressure in the chamber increases, the residence time of the powder in the high temperature zone is extended, which allows the raw material to have more sufficient time to receive the energy of the plasma, which is conducive to the full melting and evaporation of the raw material. Since the powder can more fully receive the energy of the plasma, the energy conversion rate is improved, and the plasma density can be increased. Exemplarily, the frequency of the radio frequency power supply can be 2MHz, 3MHz, 4MHz, 5MHz, 6MHz, 7MHz, 8MHz, 9MHz, 10MHz, etc.; the power of the radio frequency power supply can be 10kW, 15kW, 20kW, 25kW, 30kW, 35kW, 40kW, 45kW, 50kW, 55kW, 60kW, etc.; the pressure of the reaction chamber of the radio frequency induction device can be 0.05MPa, 0.08MPa, 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa, etc.

[0042] In some embodiments, the reaction chamber is made of quartz, and a mixed gas of high-purity argon and high-purity hydrogen is used as the protective gas of the quartz. The flow rate of the high-purity argon is 20L / min to 100L / min, and the flow rate of the high-purity hydrogen is 5L / min to 20L / min.

[0043] In the embodiment of the present application, the mixed gas of high-purity argon and high-purity hydrogen acts as a reaction chamber made of quartz. Since the quartz tube will flame at a temperature of about 1700°C, the quartz tube must be cooled; in addition, the high-purity hydrogen can capture oxygen (3H 2 +Al 2 O 3 =3H 2 O+2Al), so the high-purity spherical micron and nano-scale aluminum powder obtained in the embodiment of the present application has a lower oxygen content and a higher purity. The flow rate of high-purity argon gas can be 20L / min to 100L / min, and the flow rate of high-purity hydrogen gas can be 5L / min to 20L / min, which can effectively cool the quartz tube while reducing the oxygen content in the precursor raw material aluminum powder, thereby improving the quality of the prepared sample. Exemplarily, the flow rate of the high-purity argon gas can be 20 L / min, 25 L / min, 30 L / min, 35 L / min, 40 L / min, 45 L / min, 50 L / min, 55 L / min, 60 L / min, 65 L / min, 70 L / min, 75 L / min, 80 L / min, 85 L / min, 90 L / min, 85 L / min, 100 L / min, etc.; the flow rate of the high-purity hydrogen gas can be 5 L / min, 7 L / min, 9 L / min, 11 L / min, 13 L / min, 15 L / min, 17 L / min, 19 L / min, 20 L / min, etc.

[0044] In some embodiments, the flow rate of the working gas is 10 L / min to 50 L / min.

[0045] In the embodiment of the present application, the flow rate of the working gas can be 10L / min to 50L / min, which can provide a relatively stable working environment for the plasma, and the appropriate gas flow rate helps to maintain the temperature of the plasma, and the flow of high-purity argon can help remove impurities in the reaction chamber. Exemplarily, the flow rate of the working gas can be 10L / min, 15L / min, 20L / min, 25L / min, 30L / min, 35L / min, 40L / min, 45L / min, 50L / min, etc. The working gas can be an inert gas, such as nitrogen, argon, etc., but argon is a monatomic molecule, which can be directly ionized to form plasma without dissociation, and has low cost, so argon can be selected.

[0046] Step S1 specifically includes: turning on a high-frequency power supply, and ionizing the working gas under the action of electromagnetic induction coupling to generate high-temperature plasma.

[0047] S2, using the plasma to heat the precursor raw material aluminum powder having a set average particle size, so that the precursor raw material aluminum powder is converted into a gaseous state and a molten state;

[0048] In some embodiments, the set average particle size is 10 μm to 60 μm.

[0049] In the embodiment of the present application, the average particle size can be set to 10μm to 60μm, and the preparation of micron aluminum powder and nano aluminum powder can be achieved at the same time. The process parameters of the above-mentioned radio frequency induction plasma method are matched, so that the energy obtained by the precursor raw aluminum powder makes the surface part of the precursor raw aluminum powder particles evaporate into a gaseous state, and the inside melts into a molten state. The evaporated part of the precursor raw aluminum powder cools to form a nano powder, and the molten precursor raw aluminum powder cools to form a micro powder. If the set average particle size is lower than 10μm, it may result in only obtaining high-purity spherical nano aluminum powder; if the set average particle size is higher than 60μm, it may also be difficult to obtain micro aluminum powder and nano aluminum powder at the same time, and it is not conducive to the uniform particle size distribution of the powder. Exemplarily, the set average particle size can be 10μm, 13μm, 15μm, 18μm, 20μm, 23μm, 25μm, 28μm, 30μm, 33μm, 35μm, 36μm, 40μm, 43μm, 45μm, 48μm, 50μm, 53μm, 55μm, 58μm, 60μm, etc.

[0050] In some embodiments, the flow rate of the precursor raw material aluminum powder is 5 g / min to 50 g / min; and / or,

[0051] The flow rate of the carrier gas of the precursor raw material aluminum powder is 2L / min to 10L / min.

[0052] In the embodiment of the present application, the flow rate of the precursor raw material aluminum powder can be 5g / min to 50g / min. The flow rate of the precursor high-purity aluminum powder raw material determines the production efficiency of the radio frequency induction device to a certain extent. The appropriate flow rate of the precursor raw material aluminum powder can ensure that the unit precursor raw material aluminum powder can receive enough energy, so that the precursor raw material aluminum powder can be fully evaporated and melted. Exemplarily, the flow rate of the precursor raw material aluminum powder can be 5g / min, 10g / min, 15g / min, 20g / min, 25g / min, 30g / min, 35g / min, 40g / min, 45g / min, 50g / min, etc. The flow rate of the carrier gas of the precursor raw material aluminum powder can be 2L / min to 10L / min. The flow rate of the carrier gas must match the flow rate of the precursor high-purity aluminum powder raw material, and the precursor high-purity aluminum powder raw material can be brought into the reaction chamber evenly, continuously and stably. For example, the flow rate of the carrier gas of the precursor raw material aluminum powder can be 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, etc. The carrier gas can be an inert gas, such as nitrogen, argon, etc.

[0053] S3. Cooling the precursor raw aluminum powder in gaseous state and molten state, so that the precursor raw aluminum powder in gaseous state forms nano aluminum powder, and the precursor raw aluminum powder in molten state forms micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

[0054] In some embodiments, the cooling is performed using an air cooling method, and the flow rate of the gas used in the air cooling method is 200 L / min to 1000 L / min.

[0055] In the embodiment of the present application, during the subsequent cooling process of the precursor raw aluminum powder in a gaseous state, the gaseous aluminum atoms or molecules will gather and condense when the temperature drops rapidly. Since they are in a dispersed gaseous state, they can form particles of smaller size during cooling. When the gaseous aluminum atoms or molecules condense to form liquid droplets, the surface tension of the liquid will prompt them to develop into a spherical form. During the subsequent rapid cooling process, this spherical form is retained, and finally a spherical nano aluminum powder is obtained; when the precursor raw aluminum powder in a molten state is cooled, it will gradually shrink to form a sphere due to its own surface tension. Because the material in the molten state has a certain fluidity, it will tend to form a sphere with the smallest surface area under the influence of surface tension, and finally become a spherical micron powder with a relatively large particle size after cooling and solidification, that is, micron aluminum powder. The flow rate of cooling gas determines the cooling rate of the precursor raw aluminum powder in gaseous and molten state, and the cooling rate directly affects the particle morphology and size of micron aluminum powder and nano aluminum powder. Within a certain range, the cooling rate is positively correlated with the particle size of the particles. The cooling rate affects the particle size and morphology of the product, and when the cooling rate increases, the average particle size of the product will become smaller and the morphology will tend to be more regular spherical. This is mainly because when the cooling rate increases, the particles will be suspended in the air for a shorter time and the chance of mutual collision will decrease. However, the smaller the particle size, the more agglomeration of particles will be caused, resulting in a significant decrease in the quality of micron aluminum powder and nano aluminum powder. Different cooling rates will affect the oxidation rate of the product, and the oxidation rate of the particles is relatively low when the cooling rate is large. This may be because when the cooling gas flow rate is large, the particles will quickly cool and deposit at the bottom of the reactor, shortening the time the particles are suspended in the air, thereby reducing the degree of oxidation of the particles. Combined with the process parameters of the radio frequency induction plasma method, the gas flow rate used in the gas cooling method can be 200L / min~1000L / min. Exemplarily, the flow rate of the gas used in the air cooling method can be 200 L / min, 250 L / min, 300 L / min, 350 L / min, 400 L / min, 450 L / min, 500 L / min, 550 L / min, 600 L / min, 650 L / min, 700 L / min, 750 L / min, 800 L / min, 850 L / min, 900 L / min, 950 L / min, 1000 L / min, etc. The gas used in the air cooling method can be an inert gas, such as nitrogen, argon, etc.

[0056] In some embodiments, the precursor raw aluminum powder in gaseous state and molten state is cooled so that the precursor raw aluminum powder in gaseous state forms nano aluminum powder and the precursor raw aluminum powder in molten state forms micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time, and then further comprises:

[0057] The micron aluminum powder and the nano aluminum powder are passivated by using oxygen so that an oxide layer is formed on the surface of the micron aluminum powder and the surface of the nano aluminum powder to obtain a micron aluminum powder product and a nano aluminum powder product; wherein the flow rate of the oxygen is 0.02L / min to 0.1L / min.

[0058] In the embodiment of the present application, oxygen is used as the passivation gas to controllably passivate the micron aluminum powder and nano aluminum powder. In this way, an oxygen passivation layer with an average thickness of 5nm to 20nm can be uniformly formed on the surface of the micron aluminum powder and nano aluminum powder. The formation of this thin and uniform oxide layer prevents the further oxidation of the micron aluminum powder and nano aluminum powder, ensuring that the high-purity spherical micron and nano aluminum powders show high activity in the chemical application process and good stability during storage. The flow rate of oxygen can be 0.02L / min to 0.1L / min, which can fully realize the passivation of the micron aluminum powder and nano aluminum powder without affecting the purity of the micron aluminum powder and nano aluminum powder, and obtain a thin, uniform and complete oxygen passivation layer formed on the surface of the micron aluminum powder and nano aluminum powder. Illustratively, the flow rate of oxygen can be 0.02 L / min, 0.03 L / min, 0.04 L / min, 0.05 L / min, 0.06 L / min, 0.07 L / min, 0.08 L / min, 0.09 L / min, 0.1 L / min, etc.

[0059] In some embodiments, the weight ratio of the micron aluminum powder to the nano aluminum powder is 1:(1-9);

[0060] The shapes of the micron aluminum powder and the nano aluminum powder include at least one of the following: spherical, nearly spherical, and quasi-spherical;

[0061] The average particle size of the micron aluminum powder is 5 μm to 60 μm, and the average particle size of the nano aluminum powder is 50 nm to 300 nm.

[0062] In an embodiment of the present application, through the synergistic effect of the energy of the above-mentioned plasma and the set average particle size of the precursor raw material aluminum powder. The weight ratio of micron aluminum powder to nano aluminum powder can be regulated. The weight ratio of micron aluminum powder to nano aluminum powder can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, etc. The morphology of micron aluminum powder and nano aluminum powder can be a combination of one or more of spherical, nearly spherical, and quasi-spherical. The average particle size of micron aluminum powder can be 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, etc., and the average particle size of nano aluminum powder can be 50nm, 80nm, 100nm, 130nm, 150nm, 180nm, 200nm, 230nm, 250nm, 280nm, 300nm, etc.

[0063] The method for preparing micron aluminum powder and nano aluminum powder at the same time specifically comprises: firstly, cleaning the system for preparing micron aluminum powder and nano aluminum powder, removing impurities in the system, ensuring that the system is clean and does not contain other metal particle impurities; step 2: starting the vacuum pump, evacuating the reaction chamber until the reaction chamber maintains a high vacuum state, ensuring that the air in the chamber is basically exhausted, and then filling the chamber with inert gas to make the reaction chamber reach a certain pressure; step 3: repeating the treatment method of step 2 2 to 3 times to ensure that the gas in the chamber is pure and maintains a certain pressure; step 3 is to repeatedly "clean" the chamber with high-purity inert gas to ensure that the gas in the reaction chamber is pure and does not contain impurity gas, so as to avoid reducing the purity of the prepared metal powder. Step 4: turning on the cooling water circulation device and the cooling gas system, after the overall operation of the system is normal, introducing the working gas and the protective gas, connecting the high-frequency power supply, the working gas is ionized under the action of electromagnetic induction coupling, and high-temperature plasma is generated; step 5: starting the feeding device, introducing the carrier gas and the cooling gas. The raw materials are fed into the plasma reaction area along with the carrier gas by the feeding device, evaporated and melted by the high-temperature plasma heating, and quickly condensed into micron aluminum powder and nano aluminum powder under the action of the cooling gas and transported to the rear of the equipment; Step 6: Slowly introduce the passivation gas from the inert gas inlet to form an oxide film of uniform thickness on the surface of the powder to prevent it from further oxidation during collection. After the temperature is cooled and the atmosphere reaches equilibrium, the micron aluminum powder products and nano aluminum powder products are collected separately and vacuum-sealed for storage.

[0064] For example, Figure 2 This is a schematic diagram of a system for simultaneously preparing micron aluminum powder and nano aluminum powder provided in an embodiment of the present application; see Figure 2, including: 1-precursor aluminum powder raw material; 2-feeding system; 3-working gas inlet; 4-protective gas inlet; 5-cooling water inlet; 6-induction coil; 7-cooling gas inlet; 8-cooling water outlet; 9-exhaust emission system; 10-micron-level aluminum powder collection chamber; 11-nanometer-level aluminum powder collection chamber; 12-powder separation filter; 13-passivation gas inlet. Among them, the precursor aluminum powder raw material 1 is a high-purity aluminum powder with an average particle size of 10μm to 60μm and a purity of ≥99.9%; the feeding system 2 is used for the carrier gas and the precursor aluminum powder raw material 1 to enter the subsequent process according to the corresponding flow rate; the working gas inlet 3 is used for the plasma forming gas to enter the reaction chamber according to the corresponding flow rate to ensure the generation and stable operation of the plasma; the protective gas inlet 4 is used for the protective gas to enter the reaction chamber according to the corresponding flow rate to ensure that the equipment is well cooled, does not accumulate heat, and is not damaged by high temperature. In addition, the hydrogen in the protective gas can also capture oxygen in the precursor raw material aluminum powder and reduce the oxygen content in the prepared micron aluminum powder and nano aluminum powder; the cooling water inlet 5 is used for the entry and circulation of cooling water to ensure that the equipment is well cooled, does not accumulate heat, and is not damaged by high temperature; the induction coil 6 is used to ensure the generation and continuous and stable operation of the plasma, and the induction coil 6 is connected A high-frequency power supply is connected; a cooling gas inlet 7 is used to allow cooling gas to enter the reaction chamber quantitatively at a set speed, and to quickly cool the molten and evaporated aluminum metal vapor and droplets, so that they are condensed into spherical micron and nanometer fine particles; a cooling water outlet 8 is used for the outflow of cooling water to ensure the normal circulation of the cooling water system; an exhaust gas emission system 9 is used to discharge all input gases in the system to ensure a reasonable gas pressure in the system; a micron aluminum powder collection chamber 10 is used for the collection and processing of micron aluminum powder. When the collection chamber is about to be full, it can be removed and replaced separately to collect high-purity spherical micron aluminum powder without affecting the continuous operation of the machine and improving the continuity of preparation; a nano aluminum powder collection chamber 11 is used for the collection and processing of nano aluminum powder. When the collection chamber is about to be full, it can be removed and replaced separately to collect nano aluminum powder products without affecting the continuous operation of the machine and improving the continuity of preparation. A powder separation filter 12 is used for the screening and separation of nano powder and micro powder. The passivation gas inlet 13 is used for passivation treatment of micron aluminum powder and nano aluminum powder to ensure that a uniform oxygen passivation layer with an average thickness of 5nm to 20nm is obtained on the surface of the micron aluminum powder and nano aluminum powder.

[0065] The method for simultaneously preparing micron aluminum powder and nano aluminum powder provided in the embodiment of the present application has the following advantages:

[0066] 1. First, the working gas is made into plasma by radio frequency induction plasma method, and its energy is regulated; then, the precursor raw material aluminum powder with a set average particle size is heated by the formed plasma to promote its conversion into gaseous state and molten state; finally, the precursor raw material aluminum powder in different states is cooled to obtain nano aluminum powder and micron aluminum powder respectively, thereby realizing the simultaneous preparation of these two aluminum powders with different particle size specifications;

[0067] 2. The radio frequency induction plasma method is chosen to generate plasma because it can give plasma the characteristics of high temperature and high energy. The high-frequency electromagnetic field generated by the radio frequency power supply acts on the working gas (such as the high-purity argon gas mentioned above), excites the electrons in the gas to accelerate their movement, and then collides with the gas molecules to produce ionization, forming a plasma environment. For example, with the appropriate process parameters such as the frequency and power of the radio frequency power supply and the pressure of the reaction chamber, a plasma that meets the requirements of subsequent processes can be stably generated;

[0068] 3. Control process parameters to regulate plasma energy: The control of process parameters is crucial and will affect the energy distribution, heating area, density and other characteristics of the plasma. For example, the frequency affects the plasma range, the power determines the input energy, and the chamber pressure is related to the plasma density and the residence time of the raw materials in the high temperature area. By finely adjusting these parameters, the energy of the plasma can be accurately regulated to achieve a suitable state that can effectively process the precursor raw material aluminum powder;

[0069] 4. Use the plasma with controlled energy to heat the precursor raw material aluminum powder with a set average particle size to convert it into a gaseous state and a molten state. Here, the set average particle size of the precursor raw material aluminum powder works synergistically with the energy of the plasma. Since the plasma has high energy, when it acts on the aluminum powder particles, the energy transfer causes the surface part of the aluminum powder particles to evaporate and become a gaseous state due to obtaining sufficient heat, while the interior melts to form a molten state due to the accumulation of heat. Under the same plasma energy environment, aluminum powder particles of different particle sizes will have different surface and internal heating conditions and conversion states, so the average particle size of the precursor raw material aluminum powder needs to be set to ensure that the conversion between the gaseous state and the molten state can be achieved as expected;

[0070] 5. During the subsequent cooling process of the precursor raw aluminum powder in gaseous state, the gaseous aluminum atoms or molecules will gather and condense when the temperature drops rapidly. Since they are in a dispersed gaseous state, they can form smaller particles during cooling. When the gaseous aluminum atoms or molecules condense to form liquid droplets, the surface tension of the liquid will prompt them to develop into a spherical form. During the subsequent rapid cooling process, this spherical form is retained, and finally spherical nano aluminum powder is obtained; during the cooling of the precursor raw aluminum powder in molten state, it will gradually shrink to form a sphere due to its own surface tension. Because the material in the molten state has a certain fluidity, it will tend to form a sphere with the smallest surface area under the influence of surface tension, and finally become a spherical micron powder after cooling and solidification, that is, micron aluminum powder.

[0071] In summary, by using the radio frequency induction plasma method and the precise control of each key link, the synergistic effect of plasma energy and the particle size of the precursor raw material aluminum powder is cleverly used to achieve the simultaneous preparation of micron aluminum powder and nano aluminum powder in the same process. Compared with the method of preparing two types of aluminum powder using different processes, this simultaneous preparation method can not only improve production efficiency, but also reduce costs to a certain extent, and can ensure that the prepared micron aluminum powder and nano aluminum powder meet the corresponding application requirements in terms of quality and performance, and has important practical value in aluminum powder production and related application fields.

[0072] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for the unrecorded specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, then carry out according to general international standards, normal conditions or according to the conditions recommended by the manufacturer.

[0073] Example 1

[0074] A method for simultaneously preparing micron aluminum powder and nano aluminum powder comprises:

[0075] Using a radio frequency induction plasma method to form plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to regulate the energy of the plasma;

[0076] Using plasma to heat a precursor raw aluminum powder having a set average particle size so as to convert the precursor raw aluminum powder into a gaseous state and a molten state;

[0077] The precursor raw aluminum powder in gaseous state and molten state is cooled to make the precursor raw aluminum powder in gaseous state form nano aluminum powder and the precursor raw aluminum powder in molten state form micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

[0078] Among them, high-purity argon (Ar≥99.99%) is used as the carrier gas of the precursor high-purity aluminum powder raw material; high-purity argon (Ar≥99.99%) is used as the working gas; a mixed gas of high-purity argon (Ar≥99.99%) and high-purity hydrogen (H 2 ≥99.99%) is used as the protective gas of the quartz tube of the reaction chamber; high-purity argon (Ar≥99.99%) is used as the cooling gas; oxygen is used as the passivation gas, and the flow rate of the precursor high-purity aluminum powder raw material is 20g / min; the flow rate of the carrier gas high-purity argon is 7L / min; the flow rate of the working gas high-purity argon is 40L / min; the flow rate of the protective gas high-purity argon is 70L / min, and the flow rate of high-purity hydrogen is 15L / min; the flow rate of the cooling gas high-purity argon is 600L / min; the oxygen flow rate is 0.05L / min; the frequency of the RF power supply is 4MHz; the power is 50kW; the pressure in the reaction chamber is 0.2MPa; the set average particle size of the precursor raw material aluminum powder is 20μm, and the purity is 99.9%.

[0079] Example 2

[0080] A method for simultaneously preparing micron aluminum powder and nano aluminum powder comprises:

[0081] Using a radio frequency induction plasma method to form plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to regulate the energy of the plasma;

[0082] Using plasma to heat a precursor raw aluminum powder having a set average particle size so as to convert the precursor raw aluminum powder into a gaseous state and a molten state;

[0083] The precursor raw aluminum powder in gaseous state and molten state is cooled to make the precursor raw aluminum powder in gaseous state form nano aluminum powder and the precursor raw aluminum powder in molten state form micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

[0084] Among them, high-purity argon (Ar≥99.99%) is used as the carrier gas of the precursor high-purity aluminum powder raw material; high-purity argon (Ar≥99.99%) is used as the working gas; a mixed gas of high-purity argon (Ar≥99.99%) and high-purity hydrogen (H 2≥99.99%) is used as the protective gas of the quartz tube of the reaction chamber; high-purity argon (Ar≥99.99%) is used as the cooling gas; oxygen is used as the passivation gas, and the flow rate of the precursor high-purity aluminum powder raw material is 20g / min; the flow rate of the carrier gas high-purity argon is 7L / min; the flow rate of the working gas high-purity argon is 40L / min; the flow rate of the protective gas high-purity argon is 70L / min, and the flow rate of high-purity hydrogen is 15L / min; the flow rate of the cooling gas high-purity argon is 600L / min; the oxygen flow rate is 0.05L / min; the frequency of the RF power supply is 4MHz; the power is 60kW; the pressure in the reaction chamber is 0.2MPa; the set average particle size of the precursor raw material aluminum powder is 20μm, and the purity is 99.9%.

[0085] Example 3

[0086] A method for simultaneously preparing micron aluminum powder and nano aluminum powder comprises:

[0087] Using a radio frequency induction plasma method to form plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to regulate the energy of the plasma;

[0088] Using plasma to heat a precursor raw aluminum powder having a set average particle size so as to convert the precursor raw aluminum powder into a gaseous state and a molten state;

[0089] The precursor raw aluminum powder in gaseous state and molten state is cooled to make the precursor raw aluminum powder in gaseous state form nano aluminum powder and the precursor raw aluminum powder in molten state form micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

[0090] Among them, high-purity argon (Ar≥99.99%) is used as the carrier gas of the precursor high-purity aluminum powder raw material; high-purity argon (Ar≥99.99%) is used as the working gas; a mixed gas of high-purity argon (Ar≥99.99%) and high-purity hydrogen (H 2 ≥99.99%) is used as the protective gas of the quartz tube of the reaction chamber; high-purity argon (Ar≥99.99%) is used as the cooling gas; oxygen is used as the passivation gas, and the flow rate of the precursor high-purity aluminum powder raw material is 20g / min; the flow rate of the carrier gas high-purity argon is 7L / min; the flow rate of the working gas high-purity argon is 40L / min; the flow rate of the protective gas high-purity argon is 70L / min, and the flow rate of high-purity hydrogen is 15L / min; the flow rate of the cooling gas high-purity argon is 900L / min; the oxygen flow rate is 0.05L / min; the frequency of the RF power supply is 4MHz; the power is 50kW; the pressure in the reaction chamber is 0.2MPa; the set average particle size of the precursor raw material aluminum powder is 20μm, and the purity is 99.9%.

[0091] Example 4

[0092] A method for simultaneously preparing micron aluminum powder and nano aluminum powder comprises:

[0093] Using a radio frequency induction plasma method to form plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to regulate the energy of the plasma;

[0094] Using plasma to heat a precursor raw aluminum powder having a set average particle size so as to convert the precursor raw aluminum powder into a gaseous state and a molten state;

[0095] The precursor raw aluminum powder in gaseous state and molten state is cooled to make the precursor raw aluminum powder in gaseous state form nano aluminum powder and the precursor raw aluminum powder in molten state form micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

[0096] Among them, high-purity argon (Ar≥99.99%) is used as the carrier gas of the precursor high-purity aluminum powder raw material; high-purity argon (Ar≥99.99%) is used as the working gas; a mixed gas of high-purity argon (Ar≥99.99%) and high-purity hydrogen (H 2 ≥99.99%) is used as the protective gas of the quartz tube of the reaction chamber; high-purity argon (Ar≥99.99%) is used as the cooling gas; oxygen is used as the passivation gas, and the flow rate of the precursor high-purity aluminum powder raw material is 10g / min; the flow rate of the carrier gas high-purity argon is 7L / min; the flow rate of the working gas high-purity argon is 40L / min; the flow rate of the protective gas high-purity argon is 70L / min, and the flow rate of high-purity hydrogen is 15L / min; the flow rate of the cooling gas high-purity argon is 600L / min; the oxygen flow rate is 0.05L / min; the frequency of the RF power supply is 4MHz; the power is 50kW; the pressure in the reaction chamber is 0.2MPa; the set average particle size of the precursor raw material aluminum powder is 20μm, and the purity is 99.9%.

[0097] Example 5

[0098] A method for simultaneously preparing micron aluminum powder and nano aluminum powder comprises:

[0099] Using a radio frequency induction plasma method to form plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to regulate the energy of the plasma;

[0100] Using plasma to heat a precursor raw aluminum powder having a set average particle size so as to convert the precursor raw aluminum powder into a gaseous state and a molten state;

[0101] The precursor raw aluminum powder in gaseous state and molten state is cooled to make the precursor raw aluminum powder in gaseous state form nano aluminum powder and the precursor raw aluminum powder in molten state form micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

[0102] Among them, high-purity argon (Ar≥99.99%) is used as the carrier gas of the precursor high-purity aluminum powder raw material; high-purity argon (Ar≥99.99%) is used as the working gas; a mixed gas of high-purity argon (Ar≥99.99%) and high-purity hydrogen (H 2 ≥99.99%) is used as the protective gas of the quartz tube of the reaction chamber; high-purity argon (Ar≥99.99%) is used as the cooling gas; oxygen is used as the passivation gas, and the flow rate of the precursor high-purity aluminum powder raw material is 40g / min; the flow rate of the carrier gas high-purity argon is 7L / min; the flow rate of the working gas high-purity argon is 40L / min; the flow rate of the protective gas high-purity argon is 70L / min, and the flow rate of high-purity hydrogen is 15L / min; the flow rate of the cooling gas high-purity argon is 600L / min; the oxygen flow rate is 0.05L / min; the frequency of the RF power supply is 4MHz; the power is 50kW; the pressure in the reaction chamber is 0.2MPa; the set average particle size of the precursor raw material aluminum powder is 20μm, and the purity is 99.9%.

[0103] The performance indicators of the micron aluminum powder and nano aluminum powder prepared in Examples 1 to 5 were tested. Please see Table 1 for the test results.

[0104] Table 1 Performance indicators of micron aluminum powder and nano aluminum powder

[0105]

[0106] The micron aluminum powder and nano aluminum powder prepared in Examples 1 to 5 are all spherical. As shown in Table 1, with the increase of the raw material powder feeding rate, the proportion of micron aluminum powder increases, and the particle size of the prepared micron and nano aluminum powder increases; with the increase of power, the proportion of micron aluminum powder decreases, and the particle size of the prepared micron and nano aluminum powder decreases; with the increase of cooling gas flow rate, the particle size of the prepared micron and nano aluminum powder decreases. The preparation process is flexible and can be flexibly adjusted according to actual needs, fully meeting the raw material needs of material forming processes such as powder metallurgy and 3D printing.

[0107] Comparative Example 1

[0108] Based on the disclosure of Example 1, the difference between Comparative Example 1 and Example 1 is that the power of the RF power supply is 8 kW.

[0109] Results: The average particle size of the prepared micron aluminum powder was 17.4 μm, and the average particle size of the nano powder was 338.4 nm. The average particle size of the two particles was large, and the particle size range of the two particles was wide, and the particle size consistency was poor. In addition, the sphericity of the two particles was poor, especially the micron-sized particles were flat, still showing the morphology after mechanical processing before. The fluidity of the particles was poor, which did not meet the raw material requirements of powder metallurgy and 3D printing and other material forming processes.

[0110] Comparative Example 2

[0111] Based on the disclosure of Example 1, the difference between Comparative Example 2 and Example 1 is that the average particle size of the precursor raw material aluminum powder is set to 6 μm.

[0112] Results: Micron and nano-sized aluminum powders were not prepared at the same time, only nano-sized aluminum powders were obtained. The average particle size of nano-sized aluminum powders was 109.8nm, but the nano-powders showed obvious agglomeration. Since nanoparticles with small particle sizes have high surface energy, multiple small nanoparticles will spontaneously aggregate into large particle clusters. The agglomeration of nanoparticles will cause the powder fluidity to decrease, and the agglomeration of nanoparticles will greatly deteriorate the performance of the prepared materials in material forming processes such as powder metallurgy and 3D printing.

[0113] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

[0114] (1) The embodiment of the present application can simultaneously perform micron aluminum powder spheroidization treatment and high-purity nano aluminum powder preparation in an adjustable manner, wherein the average particle size of the nano aluminum powder is 50nm to 300nm, and the average particle size of the micro aluminum powder is 5μm to 60μm;

[0115] (2) The embodiment of the present application has very low requirements on the morphology of the raw aluminum powder, and the aluminum powder raw materials prepared by various methods such as mechanical ball milling can be applied to the present method;

[0116] (3) The embodiment of the present application adopts a plasma method to continuously heat the precursor raw material aluminum powder to prepare high-purity spherical micron and nanometer metal powders, so the production efficiency is high and suitable for mass production;

[0117] (4) In the embodiment of the present application, since the hydrogen in the protective gas can capture the oxygen in the precursor raw material aluminum powder, the high-purity spherical micrometer and nanometer aluminum powder obtained by this method has a lower oxygen content and a higher purity;

[0118] (5) In the embodiments of the present application, the micron aluminum powder product and the nano aluminum powder product are spherical, with a 5nm to 20nm oxide layer attached to the surface. The oxide layer is inert, and the aluminum powder has good fluidity and storage stability.

[0119] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied for herein.

Claims

1. A method for simultaneously preparing micron aluminum powder and nano aluminum powder, the method comprising: Using a radio frequency induction plasma method to form a plasma from a working gas, and controlling process parameters of the radio frequency induction plasma method to adjust the energy of the plasma; Using the plasma to heat the precursor raw aluminum powder having a set average particle size, so that the precursor raw aluminum powder is converted into a gaseous state and a molten state; The precursor raw aluminum powder in gaseous state and molten state is cooled to make the precursor raw aluminum powder in gaseous state form nano aluminum powder and the precursor raw aluminum powder in molten state form micron aluminum powder, so as to obtain micron aluminum powder and nano aluminum powder at the same time.

2. The method according to claim 1, characterized in that The set average particle size is 10 μm to 60 μm.

3. The method according to claim 1, characterized in that The process parameters of the radio frequency induction plasma method include: the frequency of the radio frequency power supply, the power of the radio frequency power supply and the pressure of the reaction chamber of the radio frequency induction device.

4. The method according to claim 3, characterized in that The frequency of the radio frequency power source is 2 MHz to 10 MHz; and / or, The power of the radio frequency power supply is 10kW to 60kW; and / or, The pressure of the reaction chamber of the radio frequency induction device is 0.05MPa-0.3MPa.

5. The method according to claim 3 or 4, characterized in that: The reaction chamber is made of quartz, and a mixed gas of high-purity argon and high-purity hydrogen is used as the protective gas of the quartz. The flow rate of the high-purity argon is 20L / min to 100L / min, and the flow rate of the high-purity hydrogen is 5L / min to 20L / min.

6. The method according to claim 1, characterized in that The flow rate of the working gas is 10L / min to 50L / min.

7. The method according to claim 1, characterized in that The flow rate of the precursor raw material aluminum powder is 5g / min to 50g / min; and / or, The flow rate of the carrier gas of the precursor raw material aluminum powder is 2L / min to 10L / min.

8. The method according to claim 1, characterized in that The cooling is performed using an air cooling method, and the flow rate of the gas used in the air cooling method is 200 L / min to 1000 L / min.

9. The method according to claim 1, characterized in that: The precursor raw aluminum powder in gaseous state and molten state is cooled to form nano aluminum powder from the precursor raw aluminum powder in gaseous state and micron aluminum powder from the precursor raw aluminum powder in molten state, so as to obtain micron aluminum powder and nano aluminum powder at the same time, and then further comprises: The micron aluminum powder and the nano aluminum powder are passivated by using oxygen so that an oxide layer is formed on the surface of the micron aluminum powder and the surface of the nano aluminum powder to obtain a micron aluminum powder product and a nano aluminum powder product; wherein the flow rate of the oxygen is 0.02L / min to 0.1L / min.

10. The method according to claim 1, characterized in that The weight ratio of the micron aluminum powder to the nano aluminum powder is 1:(1-9); The shapes of the micron aluminum powder and the nano aluminum powder include at least one of the following: spherical, nearly spherical, and quasi-spherical; The average particle size of the micron aluminum powder is 5 μm to 60 μm, and the average particle size of the nano aluminum powder is 50 nm to 300 nm.

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