Aluminum-lithium alloy powder green environmental protection passivation process and passivated powder

Abstract

The application discloses a passivated aluminum-lithium alloy powder and an environment-friendly passivation method thereof. The passivated aluminum-lithium alloy powder comprises an aluminum-lithium alloy core and a passivation coating film from inside to outside. The passivation liquid mainly comprises Cr(NO3)9H2O, Cr(OH)SO4, Na2MoO4 2H2O, H2ZrF6, NaH2PO4 2H2O and NH4HF2. The passivation film is formed on the surface of the aluminum-lithium alloy powder through simple soaking, filtering and drying. The aluminum-lithium alloy surface is treated by using the environment-friendly passivation method to form a uniform and dense passivation film, which effectively prevents and isolates the influence of external water vapor and oxygen on the aluminum-lithium alloy, and maintains the stability of the aluminum-lithium alloy in storage and use.

Description

Technical Field

[0001] This application relates to the field of metal powder material preparation technology, specifically to a passivated aluminum-lithium alloy, its green and environmentally friendly preparation method, and a solid propellant containing it. Background Technology

[0002] Propellants, as a class of energetic materials with unique properties, operate by releasing energy and generating gas in a regular manner, providing crucial power support for the operation of missiles, rockets, and other aerospace vehicles, thus occupying a pivotal position in the field of aerospace propulsion. In solid propellant formulations, aluminum powder has always been one of the most commonly used metallic fuel components, capable of releasing a considerable amount of combustion heat, effectively enhancing the engine's energy level and laying the foundation for high-performance operation of spacecraft. Aluminum-lithium alloys, with their inherent advantages, have become a highly promising alternative to aluminum powder, especially their unique "micro-explosion" effect, which can significantly optimize the delay problem in the ignition process of aluminum powder, as well as the undesirable phenomena such as melting and agglomeration on the propellant combustion surface and incomplete combustion, resulting in a substantial improvement in combustion efficiency and bringing new opportunities for the development of aerospace propulsion technology. However, compared to aluminum powder, aluminum-lithium alloys have higher reactivity, making them more susceptible to oxidation, especially in humid environments with high humidity, where their stability decreases significantly. This characteristic presents severe challenges and numerous inconveniences for the storage and practical application of aluminum-lithium alloys.

[0003] Currently, passivation technology for aluminum-lithium alloys has made some progress. For example, Chinese patent application CN202311413610 proposes passivation by depositing carbonyl metal on the surface of aluminum-lithium alloys. However, the atmosphere used in this method is toxic, which poses many adverse factors in actual processing and production, and has potential threats to the health of operators and the environment. In addition, some researchers have tried to use organosilane methods for coating treatment. Patent application CN202410403708 proposes a fluorosilane-catechol co-coating method. However, the organic coating film is prone to cracking and detachment during actual storage or use, which is extremely unfavorable for the long-term stable storage requirements of aluminum-lithium alloys and still needs further optimization and improvement.

[0004] Therefore, it is particularly crucial and urgent to actively develop a production process that not only conforms to the concept of green environmental protection but also ensures the high stability of the performance of aluminum-lithium alloy powder. Summary of the Invention

[0005] This application provides a passivated aluminum-lithium alloy powder and its green and environmentally friendly passivation method, aiming to solve the difficulties of aluminum-lithium alloy powder in storage, especially the poor stability in humid environments and the compatibility problem with other propellant components in the preparation of solid propellants, while making the preparation process green and environmentally friendly.

[0006] To solve the above problems, the technical solution adopted in this application is as follows:

[0007] S1. Take 0-10g of aluminum-lithium alloy Al-10Li with an aluminum content of 90wt.% and a lithium content of 10wt.% and sieve it in a glove box filled with nitrogen to select aluminum-lithium alloy particles with a particle size of 20-30μm.

[0008] S2. Prepare a passivation solution in a beaker with one or more of Cr(NO3)·9H2O and Cr(OH)SO4 at a concentration of 10-30 g / L, one or more of Na2MoO4·2H2O and H2ZrF6 at a concentration of 10-30 g / L, NaH2PO4·2H2O at a concentration of 10-30 g / L, and NH4HF2 at a concentration of 0.1-0.4 g / L. Stir the solution evenly in a magnetic stirrer.

[0009] S3. Heat the magnetic stirrer to 20-50°C, and at the same time adjust the pH of the passivation solution to 3-6 with phosphoric acid and sulfuric acid.

[0010] S4. Keep the temperature of the magnetic stirrer constant and keep the speed setting of the magnetic stirrer at 10-12. Put 1-10g of the aluminum-lithium alloy into a beaker, ultrasonically disperse for 20-30s, and passivate for 6-15min.

[0011] S5. After the reaction, the powder is filtered using a vacuum filtration device and then vacuum dried at 45-55℃ for 4-10 hours.

[0012] This application has the following beneficial effects:

[0013] 1. Trivalent chromium is used to form a composite coating with other metal salts, which can be deposited multiple times during passivation, ensuring the density and uniformity of the passivation film.

[0014] 2. The coating film prepared by the method of this application has appropriate thickness and quality, which not only ensures the isolation performance, but also avoids the problem of the coating film thickness affecting the overall combustion performance. The calorific value and combustion performance of the coated aluminum-lithium alloy powder are not significantly affected.

[0015] 3. This application has successfully achieved a green and environmentally friendly passivation process for aluminum-lithium alloys and aluminum-lithium alloy passivation processes through innovative preparation technology. The passivation solution is prepared using environmentally friendly chemicals, and the preparation process will not cause significant harm to the environment.

[0016] 4. This application has successfully prepared a passivated aluminum-lithium alloy powder with both excellent combustion performance and good stability through an innovative passivation process. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the particle structure of the aluminum-lithium alloy after passivation.

[0019] Figure 2 Scanning electron microscope image of unpassivated aluminum-lithium alloy particles;

[0020] Figure 3 This is a scanning electron microscope image of the passivated aluminum-lithium alloy. Detailed Implementation

[0021] Example 1

[0022] like Figure 1 As shown, this embodiment provides an aluminum-lithium alloy material, including an aluminum-lithium alloy core and a passivation coating film formed on the surface of the aluminum-lithium alloy core. In the aluminum-lithium alloy core, lithium accounts for 10.80 wt% and aluminum accounts for 89.20 wt%. The passivation coating film is a composite coating layer formed by trivalent chromium and other metal salts. The aluminum-lithium alloy powder material is prepared by the following method:

[0023] S1. The vacuum-stored aluminum-lithium alloy powder is sieved in an argon-filled glove box to remove impurities and select aluminum-lithium alloy powder with a particle size of 20-30μm.

[0024] S2. Prepare a passivation solution in a beaker with a concentration of 10 g / L of Cr(OH)SO4, 15 g / L of Na2MoO4·2H2O, 10 g / L of NaH2PO4·2H2O, and 0.2 g / L of NH4HF2, and stir it evenly in a magnetic stirrer.

[0025] S3. Heat the magnetic stirrer to 50°C and adjust the pH of the passivation solution to 5.

[0026] S4. Keep the temperature of the magnetic stirrer constant and keep the speed setting of the magnetic stirrer at 10. Put 5g of the aluminum-lithium alloy into the beaker, ultrasonically disperse for 25s, and passivate for 12min.

[0027] S5. After the reaction, the powder is filtered using a vacuum filtration device and then dried under vacuum at 45°C for 8 hours.

[0028] See the images of aluminum-lithium alloy powder before and after passivation. Figure 2 , Figure 3 . Figure 2 This is a scanning electron microscope image of the original aluminum-lithium alloy, showing the pores and grooves on its surface formed by the action of gas during the gas-phase preparation process. Figure 3 This is a scanning electron microscope (SEM) image of the passivated aluminum-lithium alloy. It is evident that the grooves and pores on the surface of the aluminum-lithium alloy have been covered by a dense coating layer, and the original metallographic structure of the aluminum-lithium alloy powder is absent. Furthermore, the surface coating is uniform and smooth. Therefore, this demonstrates that the coating layer formed using the coating method of this application is dense, which can improve stability while ensuring low direct adhesion of the powder, preventing agglomeration between powder particles that could affect its performance in subsequent solid propellants.

[0029] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A green and environmentally friendly passivation method for aluminum-lithium alloy powder, characterized in that, A passivation solution is prepared with one or more of Cr(NO3)·9H2O and Cr(OH)SO4 at a concentration of 10-30 g / L, one or more of Na2MoO4·2H2O and H2ZrF6 at a concentration of 10-30 g / L, NaH2PO4·2H2O at a concentration of 10-30 g / L, and NH4HF2 at a concentration of 0.1-0.4 g / L. Passivated aluminum-lithium alloy powder is obtained by soaking, filtering, and drying. The passivated aluminum-lithium alloy powder, from the inside out, comprises an aluminum-lithium alloy core and a passivation coating film. The mass of the passivation coating film is 3-5% of the mass of the passivated aluminum-lithium alloy powder. The aluminum content in the passivated aluminum-lithium alloy powder is 90-95 wt.%, and the lithium content is 5-10 wt.%.

2. The passivation method as described in claim 1, comprising the following steps: S1. Prepare the passivation solution in a beaker and stir it evenly in a magnetic stirrer; S2. Heat the magnetic stirrer to 20-50℃, and adjust the pH of the passivation solution to 3-6. S3. Keep the temperature of the magnetic stirrer constant and keep the speed setting of the magnetic stirrer at 10-12. Put 1-10g of the aluminum-lithium alloy powder into a beaker, ultrasonically disperse for 20-30s, and passivate for 6-15min. S4. After the reaction, the powder is filtered using a vacuum filtration device and then vacuum dried at 45-55℃ for 4-10 hours.

3. The passivation method as described in claim 2, characterized in that, In S2, the pH adjustment reagents are H3PO4 and H2SO4, and the pH is adjusted to 3-6. The solution is then passivated at a constant temperature of 20-50℃ for 6-15 minutes.

4. The passivation method as described in claim 2, characterized in that, The vacuum drying temperature in S4 is 45-55℃, and the drying time is 4-10 hours.

5. A solid propellant, characterized in that, Its components include passivated aluminum-lithium alloy powder obtained by the green and environmentally friendly passivation method as described in any one of claims 1-4.

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