Coated aluminum powder, and method for preparing and use thereof

Abstract

The present application belongs to the technical field of nanometer materials, and particularly relates to a coated aluminum powder, a preparation method and application thereof. The present application provides a preparation method of the coated aluminum powder, which comprises the following steps: using a protective gas as a carrier gas, using a cerium precursor gas as a deposition gas, performing vapor deposition on the surface of aluminum powder, and obtaining the coated aluminum powder through oxidation. The present application adopts a chemical vapor deposition method (CVD) to combine oxidation to form a uniform and dense coating layer (including cerium oxide and aluminum oxide) on the surface of nanometer aluminum powder, thereby significantly improving the oxidation resistance stability and high-energy reaction activity of the nanometer aluminum powder. The coating layer obtained by the above method is combined with the substrate through chemical reaction, and the binding force is strong, so that the coating layer can withstand high stress environment, extreme temperature and temperature change, and is suitable for fields of high-performance materials, catalyst carriers and the like.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a coated aluminum powder, its preparation method, and its application. Background Technology

[0002] Nano-aluminum powder, due to its high specific surface area and high reactivity, is widely used in high-energy materials (such as propellants and explosives), catalyst supports, and composite materials. However, nano-aluminum powder is highly susceptible to oxidation in air, forming an alumina layer, which reduces its activity and may even pose safety hazards. To address this issue, surface coating technology has been extensively studied, with the rare earth element cerium becoming an ideal coating material due to its excellent oxidation resistance and catalytic properties. Cerium and its compounds can release energy during reactions, thus enhancing the overall energy level of the nano-aluminum powder system. From the perspective of energetic materials, some energetic coating materials accelerate the oxidation of nano-aluminum powder through their own reactivity, improving combustion efficiency. The cerium coating layer may synergistically react with the nano-aluminum powder during combustion, promoting more complete combustion of the aluminum powder.

[0003] Currently, the main methods for preparing cerium-coated aluminum nanoparticles include the sol-gel method, chemical precipitation method, and mechanical ball milling method. However, these methods suffer from problems such as poor coating uniformity, insufficient bonding strength, or complex processes, making it difficult to meet the requirements of high-performance applications. Summary of the Invention

[0004] The purpose of this invention is to provide a coated aluminum powder, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing coated aluminum powder, comprising the following steps:

[0007] Using a protective gas as the carrier gas and a cerium precursor gas as the deposition gas, vapor deposition is performed on the surface of aluminum powder, followed by oxidation to obtain the coated aluminum powder.

[0008] Preferably, the aluminum powder has a particle size of 10~100nm and a purity of ≥99.5%.

[0009] Preferably, the cerium precursor gas includes cerium triisopropoxy gas or cerium acetylacetone gas.

[0010] Preferably, the molar ratio of cerium to aluminum powder in the cerium precursor gas is 0.05~0.2:1.

[0011] Preferably, the protective gas includes at least one of helium, neon, argon, and krypton;

[0012] The flow rate of the cerium precursor gas is 20~120 sccm.

[0013] Preferably, the temperature of the vapor deposition is 800~1000℃, the pressure is 10~100kPa, and the time is 1~3h.

[0014] Preferably, the oxidation is carried out under oxygen conditions, and the oxidation temperature is 350~450℃ for 30~120min.

[0015] The present invention also provides a coated aluminum powder prepared by the preparation method described above, comprising aluminum powder and a coating layer; the material of the coating layer comprises cerium oxide and aluminum oxide.

[0016] Preferably, the cerium oxide content in the coating layer is 80-99% by mass;

[0017] The thickness of the coating layer is 2~10nm.

[0018] The present invention also provides the application of the coated aluminum powder described in the above technical solution as a high-energy material or catalyst support.

[0019] This invention provides a method for preparing coated aluminum powder, comprising the following steps: using a protective gas as a carrier gas and a cerium precursor gas as a deposition gas, performing vapor-phase deposition on the surface of aluminum powder, followed by oxidation to obtain the coated aluminum powder. This invention employs chemical vapor deposition (CVD) combined with oxidation to form a uniform and dense coating layer on the surface of nano-aluminum powder. The coating layer material includes cerium oxide and aluminum oxide, thereby significantly improving the oxidation resistance, stability, and high-energy reactivity of the nano-aluminum powder. The coating layer obtained by the above method is chemically bonded to the substrate, exhibiting strong adhesion and the ability to withstand high-stress environments, extreme temperatures, and temperature variations, making it suitable for high-performance materials, catalyst supports, and other fields. Attached Figure Description

[0020] Figure 1 SEM image of the coated aluminum powder obtained in Example 1;

[0021] Figure 2 This is a schematic diagram of the process for preparing coated aluminum powder by vapor deposition according to the present invention;

[0022] Figure 3 This is a process flow diagram for preparing coated aluminum powder according to the present invention;

[0023] Figure 4 The images show the DSC test results of the coated aluminum powders obtained in Examples 1-3. Detailed Implementation

[0024] This invention provides a method for preparing coated aluminum powder, comprising the following steps:

[0025] Using a protective gas as the carrier gas and a cerium precursor gas as the deposition gas, vapor deposition is performed on the surface of aluminum powder, followed by oxidation to obtain the coated aluminum powder.

[0026] In this invention, the particle size of the aluminum powder is preferably 10~100nm, and the purity is preferably ≥99.5%. In this invention, before the vapor deposition, it is also preferable to pretreat the aluminum powder; the pretreatment preferably includes drying the aluminum powder under a protective atmosphere, preferably argon, and the drying temperature is preferably 80~150℃. This pretreatment can remove moisture and impurities from the surface of the aluminum powder.

[0027] In this invention, the protective gas preferably includes at least one of helium, neon, argon and krypton; using the protective gas as a carrier gas can prevent the aluminum powder from oxidizing.

[0028] In this invention, the cerium precursor gas preferably includes cerium triisopropoxy (Ce(OiPr)3) gas or cerium acetylacetone (Ce(acac)3) gas. In this invention, the flow rate of the cerium precursor gas is preferably 20-120 sccm, specifically 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, 110 sccm, or 120 sccm.

[0029] In this invention, the preparation of the cerium precursor gas preferably includes: placing a cerium precursor solution in a tube furnace, evacuating the furnace, introducing a protective atmosphere, and heating the furnace; the concentration of the cerium precursor solution is preferably 0.01~0.1 mol / L, and the solvent is preferably ethanol; the purity of the cerium precursor in the cerium precursor solution is preferably >99%. In this invention, the type of the protective atmosphere is preferably the same as the type of the carrier gas; the heating temperature is preferably 400℃. In this invention, during the heating process, the cerium precursor decomposes, for example, cerium triisopropoxy decomposes into cerium oxide and isopropanol upon heating;

[0030] Ce(OCH(CH3)2)3→CeO2+Ce2O3+(CH3)2CHOH.

[0031] In this invention, the molar ratio of cerium to aluminum powder in the cerium precursor gas is preferably 0.05 to 0.2:1, specifically 0.05:1, 0.1:1, 0.15:1, or 0.2:1.

[0032] In this invention, the preferred temperature for vapor deposition is 800~1000℃, specifically 800℃, 900℃, or 1000℃; the preferred pressure is 10~100kPa, specifically 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa, 80kPa, 90kPa, or 100kPa; and the preferred time is 1~3h, specifically 1h, 2h, or 3h. In this invention, controlling the vapor deposition temperature ensures sufficient decomposition of the cerium precursor while avoiding excessive oxidation of the aluminum powder, and controlling the pressure controls the reaction rate of the vapor deposition.

[0033] In this invention, during the vapor deposition process, after the cerium oxide generated by the thermal decomposition of the cerium precursor comes into contact with isopropanol and aluminum powder, aluminum acts as a reducing agent to remove oxygen and isopropoxy groups from the cerium oxide. The cracking of the isopropoxy groups generates small molecule organic compounds such as propylene and propane, which are discharged through the carrier gas. The chemical equation is as follows:

[0034] 3CeO2 + 4Al → 2Al2O3 + 3Ce + volatile substances.

[0035] In this invention, the oxidation is preferably carried out under oxygen conditions. The oxidation temperature is preferably 350~450℃, specifically 350℃, 400℃, or 450℃; the oxidation time is preferably 30~120 min, specifically 30 min, 50 min, 80 min, 100 min, or 120 min. During the oxidation process, the generated elemental cerium undergoes oxidation, forming a stable cerium oxide coating layer. CeO2 has a fluorite structure and is stable in air. The chemical equation is as follows:

[0036] Ce + O2 → CeO2.

[0037] In this invention, after oxidation, it is preferable to cool the obtained material to room temperature under a protective atmosphere, wherein the type of the protective atmosphere is preferably the same as the type of the carrier gas, which will not be described in detail here.

[0038] This invention also provides a coated aluminum powder prepared by the preparation method described above, comprising aluminum powder and a coating layer; the coating layer is made of cerium oxide and aluminum oxide. In this invention, the mass percentage of cerium oxide in the coating layer is preferably 80-99%; the thickness of the coating layer is preferably 2-10 nm; the thickness of the coating layer can be controlled by adjusting the precursor flow rate and the reaction time.

[0039] This invention introduces the rare earth element cerium into nano-aluminum powder using a specific precursor gas and a chemical vapor deposition coating process, thus preparing composite particles of nano-aluminum powder co-coated with alumina and cerium oxide. This invention introduces a rare earth encapsulation technique into nano-aluminum powder, and the preparation process is simple and can be used for industrial applications. Moreover, the prepared coated nano-aluminum powder composite particles show significantly improved reactivity and reaction sufficiency, providing support for improving the reactivity, reaction sufficiency, and environmental adaptability of such products.

[0040] The present invention also provides the application of the coated aluminum powder described in the above technical solution as a high-energy material or catalyst support.

[0041] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0042] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0043] Example 1

[0044] Take 10g of nano-aluminum powder with a particle size of 50nm and a purity of 99.5%, place it in a vacuum drying oven, and dry it at 80℃ for 2h under the protection of argon (purity 99.99%) to remove surface moisture and impurities, and obtain pretreated nano-aluminum powder.

[0045] Cerium triisopropoxy (Ce(OiPr)3) was selected as the cerium source precursor. A cerium precursor ethanol solution with a concentration of 0.1 mol / L was placed in a tube furnace. After evacuation, argon gas was introduced and heated to 400℃ to volatilize it into a gaseous state, thus obtaining the cerium precursor gas.

[0046] Pretreated nano-aluminum powder was placed in a CVD reaction chamber and evacuated to 10 Pa. Argon was used as the carrier gas, and cerium precursor gas (gas flow rate of 60 sccm, molar ratio of cerium to aluminum of 0.1:1) was introduced. The reaction temperature was controlled at 850℃, the pressure at 50 kPa, and the reaction time at 2 h. After vapor deposition, the carrier gas and cerium precursor gas were stopped, and oxygen was introduced. The reaction was carried out at 360℃ for 60 min to form a coating layer on the surface of the nano-aluminum powder. After the reaction was completed, the powder was cooled to room temperature under argon protection to obtain coated nano-aluminum powder with a coating thickness of about 5 nm and a cerium oxide mass percentage of 92%.

[0047] Example 2

[0048] Take 15g of nano-aluminum powder with a particle size of 30nm and a purity of 99.8%, place it in a vacuum drying oven, and dry it at 100℃ for 1.5h under the protection of argon (purity 99.99%) to remove surface moisture and impurities, and obtain pretreated nano-aluminum powder.

[0049] Cerium acetylacetone (Ce(acac)3) was selected as the cerium source precursor. A cerium precursor ethanol solution with a concentration of 0.1 mol / L was placed in a tube furnace, and after evacuation, helium gas was introduced and heated to 400°C to volatilize it into a gaseous state, thus obtaining the cerium precursor gas.

[0050] Pretreated nano-aluminum powder was placed in a CVD reaction chamber and evacuated to 20 Pa. Helium was used as the carrier gas, and cerium precursor gas (gas flow rate of 80 sccm, molar ratio of cerium to aluminum of 0.15:1) was introduced. The reaction temperature was controlled at 850 °C, the pressure at 80 kPa, and the reaction time at 1.5 h. After vapor deposition, the carrier gas and cerium precursor gas were stopped, and oxygen was introduced. The reaction was carried out at 360 °C for 60 min to form a coating layer on the surface of the nano-aluminum powder. After the reaction was completed, the powder was cooled to room temperature under argon protection to obtain coated nano-aluminum powder with a coating thickness of about 3 nm and a cerium oxide mass percentage of 86%.

[0051] Example 3

[0052] Take 20g of nano-aluminum powder with a particle size of 80nm and a purity of 99.6%, place it in a vacuum drying oven, and dry it at 90℃ for 2h under the protection of argon (purity 99.99%) to remove surface moisture and impurities, and obtain pretreated nano-aluminum powder.

[0053] Cerium triisopropoxy (Ce(OiPr)3) was selected as the cerium source precursor. A cerium precursor ethanol solution with a concentration of 0.1 mol / L was placed in a tube furnace. After evacuation, argon gas was introduced and heated to 400℃ to volatilize it into a gaseous state, thus obtaining the cerium precursor gas.

[0054] Pretreated nano-aluminum powder was placed in a CVD reaction chamber and evacuated to 15 Pa. Argon was used as the carrier gas, and cerium precursor gas (gas flow rate of 70 sccm, molar ratio of cerium to aluminum of 0.2:1) was introduced. The reaction temperature was controlled at 850 °C, the pressure at 60 kPa, and the reaction time at 2.5 h. After vapor deposition, the carrier gas and cerium precursor gas were stopped, and oxygen was introduced. The reaction was carried out at 360 °C for 60 min to form a coating layer on the surface of the nano-aluminum powder. After the reaction was completed, the powder was cooled to room temperature under argon protection to obtain coated nano-aluminum powder with a coating thickness of about 8 nm and a cerium oxide mass percentage of 89%.

[0055] Performance testing

[0056] Figure 1The results are SEM test results of the coated aluminum powder obtained in Example 1. The coated nano aluminum powder obtained in this example has a uniform continuous shell layer on its surface with a thickness of about 5 nm.

[0057] Figure 2 This is a schematic diagram of the process for preparing coated aluminum powder by vapor deposition according to the present invention. Figure 3 This is a process flow diagram for preparing coated aluminum powder according to the present invention (the post-processing includes oxidation).

[0058] Figure 4 The DSC test results of the coated aluminum powders obtained in Examples 1-3 show that, compared with pure aluminum powder, the coated aluminum powders obtained in this invention have strong exothermic peak positions that are advanced by 90.6℃ (1072.8℃→982.2℃ in Example 1), 91.3℃ (1072.8℃→981.5℃ in Example 2), and 65.3℃ (1072.8℃→1007.5℃), respectively, and the peak height is significantly higher. This indicates that the coated aluminum powders prepared in this invention have more concentrated exothermic activity, a faster reaction rate, and a more concentrated exothermic peak position, demonstrating that the coating layer significantly improves the material's antioxidant stability and high-energy reactivity.

[0059] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing coated aluminum powder, characterized in that, Includes the following steps: Using a protective gas as the carrier gas and a cerium precursor gas as the deposition gas, vapor deposition is performed on the surface of aluminum powder, and the coated aluminum powder is obtained by oxidation. The cerium precursor gas is cerium triisopropoxy gas or cerium acetylacetone gas; The vapor deposition temperature is 800~1000℃, the pressure is 10~100kPa, and the time is 1~3h; The oxidation is carried out under oxygen conditions, at a temperature of 350~450℃, for a time of 30~120min; The coated aluminum powder includes aluminum powder and a coating layer; the coating layer is made of cerium oxide and aluminum oxide.

2. The preparation method according to claim 1, characterized in that, The aluminum powder has a particle size of 10~100nm and a purity of ≥99.5%.

3. The preparation method according to claim 1, characterized in that, The molar ratio of cerium to aluminum powder in the cerium precursor gas is 0.05~0.2:

1.

4. The preparation method according to claim 1, characterized in that, The protective gas includes at least one of helium, neon, argon, and krypton; The flow rate of the cerium precursor gas is 20~120 sccm.

5. The coated aluminum powder prepared by the preparation method according to any one of claims 1 to 4, characterized in that, It includes aluminum powder and a coating layer; the coating layer is made of cerium oxide and aluminum oxide.

6. The coated aluminum powder according to claim 5, characterized in that, The coating layer contains 80-99% cerium oxide by mass. The thickness of the coating layer is 2~10nm.

7. The application of the coated aluminum powder as described in claim 5 or 6 as a high-energy material or catalyst support.

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