High-temperature-resistant stabilized modified aluminum-lithium alloy fuel and preparation method thereof

Abstract

The invention belongs to the technical field of energetic materials, and particularly relates to a high-temperature-resistant stabilized modified aluminum-lithium alloy fuel and a preparation method thereof. The preparation method comprises the following steps: S1, adding aluminum-lithium alloy powder into an alcohol reagent, stirring and dispersing, and carrying out suction filtration and drying to obtain pretreated powder; s2, organic phosphate and a titanate reagent are added into an organic solvent for ultrasonic dissolution and dispersion, and an organic mixed solution is obtained; and S3, the pretreated powder obtained in the step S1 is added into the organic mixed solution obtained in the step S2, stirring reaction is conducted till the solvent is completely volatilized, then vacuum drying is conducted, and the modified aluminum-lithium alloy powder is obtained. The modified alloy powder disclosed by the invention can be kept in hot water at 50-70 DEG C for 3 hours without obvious hydrogen evolution reaction, and is well cured when being applied to a solid propellant formula, so that the heat-resistant high stability of an aluminum-lithium alloy fuel and the compatibility of the aluminum-lithium alloy fuel in the solid propellant are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energetic materials, and in particular relates to a high-temperature resistant and stabilized modified aluminum-lithium alloy fuel and a preparation method thereof. Background Art

[0002] Aluminum-based alloys are a promising approach to modifying aluminum powders for improved combustion efficiency. Lithium is an attractive alloying element, with a higher heat of combustion (58.3 kJ / g) than Al (31.4 kJ / g) and a lower melting point (460 K) than Al (933.4 K). This offers a promising strategy for modifying aluminum powders to improve combustion efficiency and reduce losses in two-phase flow. Research has found that the addition of Al-Li alloy powder to propellants not only effectively increases the propellant's specific impulse but also significantly reduces the HCl content in the combustion products of chlorine-containing oxidizer systems. However, the addition of Li alters the structure of the aluminum powder's surface oxide layer, accelerating its breakdown and negatively impacting storage. Furthermore, Li is a relatively reactive element. Higher Li content in Al-Li alloy fuels increases their activity. This inherent stability issue not only compromises their curing properties in subsequent energetic material applications but also poses a threat to their safety, limiting their use in various energetic materials, including propellants. Therefore, it is necessary to stabilize the aluminum-lithium alloy powder to improve its performance stability during storage and transportation and its process performance in application.

[0003] At present, there has been some progress in the modification of aluminum-lithium alloy powder. The inventor previously disclosed a modified aluminum-lithium alloy fuel with excellent wet-heat stability and compatibility and its preparation method (Chinese patent application 202311265142.6). However, studies have found that the single-layer protective layer may fall off during mechanical kneading due to weak bonding force in actual applications, causing the aluminum-lithium alloy powder to react with the components in the propellant and thus affecting the actual application effect of the propellant. After modification and passivation treatment with organic phosphate + titanate reagents, a multi-layer protective layer of inorganic and organic layers can be formed on the surface of the aluminum-lithium alloy. The organic layer on the surface can not only improve the anti-hydration stability of the aluminum-lithium alloy, but also has good compatibility with components such as nitrates and end-hydroxy polybutadiene in the propellant without affecting the curing of the propellant formula. The bottom inorganic layer can be tightly combined with the aluminum-lithium alloy powder and can improve the mechanical properties of the grain to a certain extent.

[0004] To this end, the present invention provides a high-temperature stabilization preparation method for aluminum-lithium alloy powder based on organic coating technology, so as to improve the application efficiency of aluminum-lithium alloy powder as a high-energy metal fuel in the field of solid rocket propellant and mixed explosives. Summary of the Invention

[0005] The present invention addresses the application bottleneck problems such as aluminum-lithium alloy powder being easily oxidized and releasing hydrogen in a hot and humid environment, having poor stability resulting in a decrease in alloy fuel performance, and having poor compatibility with common components of solid rocket propellants affecting the solidification and molding of the propellant. A high-temperature-resistant and stabilized modified aluminum-lithium alloy fuel and a preparation method thereof are proposed. After modified passivation treatment, a multi-layer protective layer of inorganic and organic layers can be formed on the surface of the aluminum-lithium alloy, in order to obtain a modified aluminum-lithium alloy fuel that can maintain high heat resistance, stability and compatibility, thereby improving the application efficiency of aluminum-lithium alloy powder as a high-energy metal fuel in the fields of solid rocket propellants and mixed explosives.

[0006] To this end, the present invention provides the following technical solutions.

[0007] One aspect of the present invention provides a method for preparing a high-temperature resistant and stabilized modified aluminum-lithium alloy powder, comprising the following steps:

[0008] S1: adding aluminum-lithium alloy powder to an alcohol reagent, stirring and dispersing the mixture, and filtering and drying the mixture to obtain a pretreated powder;

[0009] S2: adding an organic phosphate and a titanate reagent into an organic solvent and performing ultrasonic dissolution and dispersion to obtain an organic mixed solution;

[0010] S3: adding the pretreated powder obtained in step S1 to the organic mixed solution obtained in step S2, stirring and reacting until the solvent is completely evaporated, and then vacuum drying to obtain a modified aluminum-lithium alloy powder.

[0011] In a preferred embodiment of the present invention, in step S1, the stirring and dispersing time is 30 to 60 minutes.

[0012] In a preferred embodiment of the present invention, in step S3, the stirring reaction is carried out at 70-90°C, preferably at 80°C.

[0013] In a preferred embodiment of the present invention, the aluminum-lithium alloy powder is a spherical aluminum-lithium alloy powder. Preferably, the lithium content of the spherical aluminum-lithium alloy powder is 5%-10%, and the median diameter is 2-50 μm.

[0014] In a preferred embodiment of the present invention, the mass ratio of the aluminum-lithium alloy powder in step S1 to the organic phosphate in step S2 is 1:0.01-1:0.03; the mass ratio of the aluminum-lithium alloy powder in step S1 to the titanate in step S2 is 1:0.01-1:0.03.

[0015] In a preferred embodiment of the present invention, in step S1, the alcohol reagent is selected from any one of methanol, ethanol, isopropanol, pentaerythritol, allyl alcohol, propylene glycol, and ethylene glycol, or a mixture of two or more thereof.

[0016] In a preferred embodiment of the present invention, in step S2, the organic phosphate is selected from any one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, tetraethyl pyrophosphate, tris(2-chloroethyl) phosphate, tributyl phosphate, diphenyl isooctyl phosphate, tricresyl phosphate, and triallyl phosphate, or a mixture of two or more thereof.

[0017] In a preferred embodiment of the present invention, in step S2, the titanate reagent is selected from any one of chloroisopropyl tris(dioctylphosphoyl) titanate, isopropyl tris(stearoyl) titanate, di(dioctyl pyrophosphate) oxyacetic acid titanate, di(dioctyl phosphite) tetraisopropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, trifluoroacetyl titanate, and titanate-siloxane, or a mixture of two or more thereof.

[0018] In a preferred embodiment of the present invention, in step S2, the organic solvent is selected from any one of petroleum ether, diethyl ether, ethyl acetate, N,N-dimethylformamide, or a mixture of two or more thereof.

[0019] Another aspect of the present invention provides a high-temperature resistant and stabilized modified aluminum-lithium alloy powder, wherein the modified aluminum-lithium alloy powder is prepared by the preparation method of the present invention.

[0020] In a preferred embodiment of the present invention, the content of the organic phosphate + titanate modified layer is ≤ 3.0 wt.% of the mass of the aluminum-lithium alloy powder.

[0021] Compared with the prior art solutions, the present invention has at least the following advantages:

[0022] 1. The present invention uses an alcohol reagent to pretreat the aluminum-lithium alloy powder to reduce the high chemical activity of the aluminum-lithium alloy powder surface, and then uses organic phosphate + titanate to passivate it. After the modified passivation treatment with organic phosphate + titanate, a multi-layer protective layer of inorganic layer and organic layer can be formed on the surface of the aluminum-lithium alloy. The bottom layer as an inorganic layer can be tightly combined with the aluminum-lithium alloy, and the organic layer on the surface can improve the hydration stability of the aluminum-lithium alloy, and can remain in 50-70°C hot water for 3 hours without obvious hydrogen evolution reaction. It is well cured when applied to the solid propellant formulation, has a dense cross-section and is free of pores, and significantly improves the high heat stability of the aluminum-lithium alloy fuel and its compatibility in the solid propellant while ensuring the energy density (mass combustion calorific value>31kJ / g).

[0023] 2. The modified aluminum-lithium alloy fuel preparation method provided by the present invention is simple, the process is stable and reliable, and the equipment investment is low. At the same time, the reagents and agents involved in the modification treatment are cheap and easy to obtain, and low-cost mass production can be easily achieved, which can provide strong support for the large-scale practical application of aluminum-lithium alloy fuel in solid propellants.

[0024] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Comparison of the stability of Al-5Li alloy powder before and after modification; (a) and (b) are the stability results of Al-5Li alloy powder without surface modification in pure water at room temperature (25°C) and hot water at 70°C, respectively; (c) is the stability result of the modified Al-5Li alloy powder (AL-1) of Example 1 in hot water at 70°C; (d) is the stability result of the modified Al-5Li alloy powder (AT-1) of Comparative Example 1 in hot water at 70°C; Figure 2 The figures are the quantitative hydrogen evolution test results of the modified Al-5Li alloy powder; the left figure is the quantitative hydrogen evolution test result of the modified Al-5Li alloy powder (AL-1) of Example 1, and the right figure is the quantitative hydrogen evolution test result of the modified Al-5Li alloy powder (AT-1) of Comparative Example 1; Figure 3 The SEM analysis results of Al-5Li alloy powder raw material and Al-5Li modified alloy powder; wherein (a) is the SEM analysis result of Al-5Li alloy powder raw material of Example 1, and (b) is the SEM analysis result of modified Al-5Li alloy powder (AL-1) of Example 1; Figure 4 The figure compares the curing effects of Al-5Li alloy powder before and after modification in a certain formula propellant; wherein, (a) is the Al-5Li alloy powder raw material of Example 1; (b) is the modified Al-5Li alloy powder (AL-1) of Example 1. DETAILED DESCRIPTION

[0026] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1:

[0028] S1: At room temperature, 20 g of Al-5Li alloy powder with a median diameter of 30 pm was added to 100 mL of ethylene glycol, mechanically stirred at a speed of 400 rpm for 30 min, then filtered, and then dried in a vacuum drying oven at 70 °C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0029] S2: 0.2 g of trimethyl phosphate and 0.2 g of chloroisopropyl tris(dioctylphosphato) titanate were added to 100 mL of ethyl acetate and ultrasonically dispersed for 5 min to obtain an ethyl acetate mixed solution.

[0030] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the ethyl acetate mixed solution obtained in S2, and mechanically stirred at 400 rpm in a 80 °C water bath until the solvent was completely volatilized, and then vacuum dried in a 70 °C vacuum drying oven for 60 min to obtain a modified Al-5Li alloy fuel, labeled as AL-1.

[0031] The content of the modified layer was calculated to be 0.92 wt.% of the mass of the aluminum-lithium alloy powder.

[0032] Stability of the modified Al-5Li alloy fuel: The AL-1 modified aluminum-lithium alloy fuel was tested for quantitative hydrogen evolution in hot water at 70 °C, with magnetic stirring at 300 rpm for 3 h, and no hydrogen gas was produced. Figure 2 (Left), and the mass combustion heat value did not decrease significantly compared to the original powder (Table 1).

[0033] Compatibility of the modified Al-5Li alloy fuel: A certain formula of solid propellant containing the AL-1 modified aluminum-lithium alloy fuel was completely cured during the curing process, and the cross-section was dense and free of pores Figure 4 (b)), showing good compatibility with other components of the propellant.

[0034] Example 2:

[0035] S1: At room temperature, 20 g of Al-5Li alloy powder with a median diameter of 30 pm was added to 100 mL of ethylene glycol, mechanically stirred at a speed of 400 rpm for 30 min, then filtered, and then dried in a vacuum drying oven at 70 °C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0036] S2: 0.2 g of trimethyl phosphate and 0.2 g of chloroisopropyl tris(dioctylphosphato) titanate were added to 100 mL of ethyl acetate and ultrasonically dispersed for 5 min to obtain an ethyl acetate mixed solution.

[0037] S3: The pretreated Al-5Li alloy powder obtained in S1 was added to the petroleum ether mixed solution obtained in S2, and was mechanically stirred at 400 rpm in a water bath at 80 °C until the solvent completely volatilized, and then was vacuum dried in a vacuum drying oven at 70 °C for 60 min to obtain a modified Al-5Li alloy fuel, labeled as AL-2.

[0038] The content of the modified layer was calculated to be 1.83 wt.% of the mass of the Al-5Li alloy powder.

[0039] Stability of the modified Al-5Li alloy fuel: The AL-2 modified Al-5Li alloy fuel was subjected to quantitative hydrogen evolution testing in hot water at 70 °C, and no hydrogen gas was generated under magnetic stirring at 300 rpm for 3 h, and the mass combustion heat value was equivalent to that of the original powder (Table 1).

[0040] Compatibility of the modified Al-5Li alloy fuel: Similar to AL-1, a certain formula of a solid propellant containing the AL-2 modified Al-5Li alloy fuel was completely cured during the curing process, and the cross section was dense and free of pores, and also showed good propellant component compatibility.

[0041] Example 3:

[0042] S1: At room temperature, 100 g of Al-5Li alloy powder with a median diameter of 10 pm was added to 500 mL of ethylene glycol, and was mechanically stirred at a speed of 400 rpm for 30 min and then was suction filtered, and then was dried in a vacuum drying oven at 70 °C for 60 min to obtain pretreated Al-5Li alloy powder.

[0043] S2: 3 g of triphenyl phosphate and 2.4 g of titanium bis(dioctyl pyrophosphato) oxoacetate were added to 300 mL of an N,N-dimethylformamide solution and were ultrasonically dispersed for 5 min to obtain an N,N-dimethylformamide mixed solution.

[0044] S3: The pretreated Al-5Li alloy powder obtained in S1 was added to the N,N-dimethylformamide mixed solution obtained in S2, and was mechanically stirred at 400 rpm in a water bath at 80 °C until the solvent completely volatilized, and then was vacuum dried in a vacuum drying oven at 70 °C for 90 min to obtain a modified Al-5Li alloy fuel, labeled as AL-3.

[0045] The content of the modified layer was calculated to be 2.91 wt.% of the mass of the Al-5Li alloy powder.

[0046] Stability of the modified Al-5Li alloy fuel: The AL-3 modified Al-5Li alloy fuel was subjected to quantitative hydrogen evolution testing in hot water at 70 °C, and no visible hydrogen gas was generated under magnetic stirring at 300 rpm for 3 h, and the mass combustion heat value was not significantly decreased compared to the original powder (Table 1).

[0047] Compatibility of modified Al-5Li alloy fuel: Similar to AL-1, a solid propellant containing AL-3 modified aluminum-lithium alloy fuel has a dense and defect-free cross-section after solidification, indicating that AL-3 modified aluminum-lithium alloy fuel has good compatibility with propellant components.

[0048] Example 4:

[0049] S1: At room temperature, 60 g of Al-5Li alloy powder with a median diameter of 35 μm was added to 300 mL of methanol, mechanically stirred at 400 rpm for 30 min, and then filtered. Then, it was dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0050] S2: 1.2 g of triphenyl phosphite and 1.2 g of tetraisopropyl di(dioctyl phosphite) titanate oxyacetate were added to 500 mL of ethyl acetate and ultrasonically dispersed for 5 minutes to obtain an ethyl acetate mixed solution.

[0051] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the ethyl acetate mixed solution obtained in S2, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated, and then vacuum dried in a 70°C vacuum drying oven for 90 minutes to obtain a modified Al-5Li alloy fuel.

[0052] According to calculation, the content of the modified layer is 1.89 wt.% of the mass of the aluminum-lithium alloy powder.

[0053] Example 5:

[0054] S1: At room temperature, 100 g of Al-5Li alloy powder with a median diameter of 8 μm was added to 500 mL of isopropanol, mechanically stirred at 400 rpm for 30 min, and then filtered. The mixture was then dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0055] S2: 2.0 g of dimethyl methylphosphonate and 2.0 g of tetraisopropyl titanate were added to 500 mL of ethyl acetate and ultrasonically dispersed for 5 minutes to obtain an ethyl acetate mixed solution.

[0056] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the ethyl acetate mixed solution obtained in S2, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated, and then vacuum dried in a 70°C vacuum drying oven for 90 minutes to obtain a modified Al-5Li alloy fuel.

[0057] According to calculation, the content of the modified layer is 1.75 wt.% of the mass of the aluminum-lithium alloy powder.

[0058] Example 6:

[0059] S1: At room temperature, 100 g of Al-5Li alloy powder with a median diameter of 16 μm was added to 500 mL of propylene alcohol, mechanically stirred at 400 rpm for 30 min, and then filtered. The mixture was then dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0060] S2: 2.0 g of tetraethyl pyrophosphate and 2.0 g of tetrabutyl titanate were added to 500 mL of ethyl acetate and ultrasonically dispersed for 5 min to obtain an ethyl acetate mixed solution.

[0061] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the ethyl acetate mixed solution obtained in S2, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated, and then vacuum dried in a 70°C vacuum drying oven for 90 minutes to obtain a modified Al-5Li alloy fuel.

[0062] According to calculation, the content of the modified layer is 1.82 wt.% of the mass of the aluminum-lithium alloy powder.

[0063] Example 7:

[0064] S1: At room temperature, 100 g of Al-5Li alloy powder with a median diameter of 40 μm was added to 500 mL of ethylene glycol, mechanically stirred at 400 rpm for 30 min, and then filtered. Then, the mixture was dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0065] S2: 3.0 g of tris(2-chloroethyl) phosphate and 3.0 g of trifluoroacetyl titanate were added to 500 mL of ethyl acetate and ultrasonically dispersed for 5 minutes to obtain an ethyl acetate mixed solution.

[0066] S3: The pretreated aluminum-lithium alloy powder obtained above was added to an ethyl acetate mixed solution, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated. The powder was then vacuum dried in a 70°C vacuum drying oven for 90 minutes to obtain a modified Al-5Li alloy fuel.

[0067] According to calculation, the content of the modified layer is 2.82 wt.% of the mass of the aluminum-lithium alloy powder.

[0068] Example 8:

[0069] S1: At room temperature, 100 g of Al-5Li alloy powder with a median diameter of 45 μm was added to 500 mL of ethanol, mechanically stirred at 400 rpm for 30 min, and then filtered. Then, it was dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0070] S2: 3.0 g of diphenyl isooctyl phosphate and 3.0 g of trifluoroacetyl titanate were added to 500 mL of ethyl acetate and ultrasonically dispersed for 5 minutes to obtain an ethyl acetate mixed solution.

[0071] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the ethyl acetate mixed solution obtained in S2, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated, and then vacuum dried in a 70°C vacuum drying oven for 90 minutes to obtain a modified Al-5Li alloy fuel.

[0072] According to calculation, the content of the modified layer is 2.88 wt.% of the mass of the aluminum-lithium alloy powder.

[0073] Example 9:

[0074] S1: At room temperature, 50 g of Al-5Li alloy powder with a median diameter of 50 μm was added to 250 mL of ethanol, mechanically stirred at 400 rpm for 30 min, and then filtered. The mixture was then dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0075] S2: 0.5 g of tricresyl phosphate and 0.5 g of isopropyl tri(stearyl) titanate were added to 250 mL of N,N-dimethylformamide solution and ultrasonically dispersed for 5 min to obtain an N,N-dimethylformamide mixed solution.

[0076] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the N,N-dimethylformamide mixed solution obtained in S2, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated, and then vacuum dried in a 70°C vacuum drying oven for 90 minutes to obtain a modified Al-5Li alloy fuel.

[0077] According to calculation, the content of the modified layer is 0.87 wt.% of the mass of the aluminum-lithium alloy powder.

[0078] Example 10:

[0079] S1: At room temperature, 100 g of Al-5Li alloy powder with a median diameter of 24 μm was added to 500 mL of isopropanol, mechanically stirred at 400 rpm for 30 min, and then filtered. The mixture was then dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0080] S2: 2.5 g of triallyl phosphate and 2.5 g of di(dioctyl pyrophosphate)oxyacetic acid titanate were added to 500 mL of petroleum ether solution and ultrasonically dispersed for 5 minutes to obtain a petroleum ether mixed solution.

[0081] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the petroleum ether mixed solution obtained in S2, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated, and then vacuum dried in a 70°C vacuum drying oven for 90 minutes to obtain a modified Al-5Li alloy fuel.

[0082] According to calculation, the content of the modified layer is 2.37 wt.% of the mass of the aluminum-lithium alloy powder.

[0083] Comparative Example 1:

[0084] S1: At room temperature, 20 g of Al-5Li alloy powder with a median diameter of 30 μm was added to 100 mL of ethylene glycol, mechanically stirred at 400 rpm for 30 min, and then filtered. The mixture was then dried in a vacuum drying oven at 70°C for 60 min to obtain pretreated aluminum-lithium alloy powder.

[0085] S2: 0.2 g of tetraethyl silicate and 0.2 g of γ-aminopropyltriethoxysilane were dissolved in 100 mL of ethyl acetate and ultrasonically dispersed for 5 min to obtain an ethyl acetate mixed solution.

[0086] S3: The pretreated aluminum-lithium alloy powder obtained in S1 was added to the ethyl acetate mixed solution obtained in S2, and mechanically stirred at 400 rpm in an 80°C water bath until the solvent was completely evaporated. The powder was then dried in a vacuum drying oven at 70°C for 60 min to obtain a modified Al-5Li alloy fuel, which was labeled AT-1.

[0087] According to calculation, the content of the modified layer is 0.88 wt.% of the mass of the aluminum-lithium alloy powder.

[0088] Stability of modified Al-5Li alloy fuel: AT-1 modified aluminum-lithium alloy fuel was subjected to quantitative hydrogen evolution test in 70℃ hot water with magnetic stirring at 300 rpm. A large amount of hydrogen was generated after about 5 minutes ( Figure 2 (right figure)), while the mass combustion calorific value is significantly lower than that of the original powder (Table 1).

[0089] Test Example 1: Mass Combustion Calorific Value Test

[0090] This test investigated the mass combustion calorific value of the modified Al-5Li alloy fuel prepared in Examples 1-3 and Comparative Example 1. The specific method included the following: Accurately weigh 0.9-1.1g (accurate to 0.0002g) of the analytical sample into a crucible, gently place the crucible on an oxygen bomb stand, and connect each end to the electrode column with an ignition wire. The ignition wire must maintain good contact with the sample and not directly contact the crucible. Add 10mL of distilled water to the oxygen bomb, tighten the bomb cover, and slowly fill the bomb with 3.0MPa of oxygen using an oxygenator for at least 15 seconds. The bomb was then placed in an inner cylinder, and data such as sample mass, sulfur, hydrogen, and moisture were entered. The upper cover was closed, and the test button was clicked to start the test. After the test, the values ​​were read and recorded to complete the test. The test results are shown in Table 1.

[0091] Table 1 Test results of mass combustion calorific value of Al-5Li alloy powder before and after modification

[0092]

[0093]

[0094] The results in Table 1 show that the mass calorific value of the Al-5Li alloy powders (AL-1, AL-2, and AL-3, respectively) obtained after the modification treatments of Examples 1-3 does not show a significant decrease compared to the original powder (Al-5Li alloy powder), indicating that the energy density of the Al-5Li alloy powder can still be maintained after the modification treatment. However, the mass calorific value of the modified Al-5Li alloy powder (AT-1) obtained by the method of Comparative Example 1 is significantly lower than that of the original powder, indicating that the modification treatment of Comparative Example 1 cannot effectively maintain the energy density of the Al-5Li alloy powder.

[0095] Test Example 2: Stability Test

[0096] This test example investigated the stability of the modified Al-5Li alloy powders prepared in Example 1 of the present invention and Comparative Example 1.

[0097] 1. Stability test in pure water

[0098] Test method: Pour 1700mL of pure water into a water bath and set the temperature to 70℃. When the temperature reaches 70℃, weigh 20g of powder and 60g of pure water and add them into a 250mL beaker. Place the beaker in a 70℃ water bath and stir mechanically at a stirring speed of 200rpm for 180min. Observe the state of the powder to see if any reaction occurs (a lot of bubbles) and whether the solution is clear.

[0099] The test results are shown in Figure 1 ,in, Figure 1 (a) and Figure 1(b) are the stability results of Al-5Li alloy powder without surface modification in pure water at room temperature (25℃) and hot water at 70℃, respectively. Figure 1 (c) is the stability result of the modified Al-5Li alloy powder (AL-1) of Example 1 in hot water at 70°C. Figure 1 (d) is the stability result of the modified Al-5Li alloy powder (AT-1) of Comparative Example 1 in hot water at 70°C.

[0100] like Figure 1 As shown in (a) and (b), the Al-5Li alloy powder without any modification treatment continuously produces bubbles in pure water at room temperature (~25℃) and undergoes obvious hydrogen evolution reaction; in hot water at 70℃, a violent hydrogen evolution reaction occurs, producing a large number of bubbles; Figure 1 As shown in (c), after pretreatment with alcohol reagents and modification with organic phosphate + titanate, the obtained Al-5Li alloy powder (AL-1) remained stable in 70°C hot water for 3.0 h, no visible bubbles were generated, and the aqueous solution remained clear and transparent, indicating that the pretreatment with alcohol reagents and modification with organic phosphate + titanate significantly improved the stability of the obtained Al-5Li alloy powder (AL-1) in hot water; Figure 1 As shown in Figure (d), after alcohol pretreatment and modification with tetraethyl silicate + γ-aminopropyltriethoxysilane, the resulting Al-5Li alloy powder (AT-1) undergoes a vigorous oxidative hydrogen evolution reaction in 70°C hot water, generating numerous bubbles and causing the solution to become turbid. These results demonstrate that the stability of the modified Al-5Li alloy powder is significantly improved after alcohol pretreatment and modification with organophosphate + titanate.

[0101] 2. Quantitative hydrogen evolution test

[0102] Test method: Weigh 60g of distilled water and add it to a 250mL Erlenmeyer flask with a rotor. Place the flask in a 2000mL beaker containing 500mL of pure water and place it on a magnetic stirrer to heat at 70℃; take a 250mL graduated cylinder filled with water and invert it into a 1000mL beaker containing 400mL of pure water, and adjust its liquid level to the 0 scale line; when the temperature rises to 70℃, weigh 20g of powder and pour it into the Erlenmeyer flask and connect it to the lower end of the condenser. The upper outlet of the condenser is sealed with a rubber stopper with a glass tube. One end of the hose is connected to the glass tube, and the other end is passed into the inverted 250mL graduated cylinder and must not exceed the liquid level; connect the condenser to a chiller, start the chiller, turn on the magnetic stirrer and start the test; after stabilization for 10 minutes, record the time and the reading of the graduated cylinder, and then record it every 30 minutes. After the required time or when a significant reaction occurs (a lot of bubbles, the liquid level in the graduated cylinder drops rapidly), the test is terminated. (For detailed diagram and details of the test device, please refer to the Chinese invention patent application "A test device and evaluation method for the anti-hydration performance of passivated aluminum powder" CN115791586A).

[0103] The test results are shown in Figure 2 ,in, Figure 2 (Left) is the quantitative hydrogen evolution test result of the modified Al-5Li alloy powder (AL-1) of Example 1. Figure 2 (Right) shows the quantitative hydrogen evolution test results of the modified Al-5Li alloy powder (AT-1) of Comparative Example 1.

[0104] Figure 2 The quantitative hydrogen evolution test results (left figure) show that the Al-5Li alloy powder (AL-1) obtained after the modification treatment in Example 1 did not undergo hydrogen evolution reaction within 3.0 h under magnetic stirring at 300 rpm in 70 ℃ hot water, showing excellent thermal stability. Figure 2 The quantitative hydrogen evolution test results (right figure) show that the Al-5Li alloy powder (AT-1) obtained after the modification treatment of Comparative Example 1 produces a large amount of hydrogen within 3.0 hours in 70°C hot water.

[0105] Test Example 3: Powder Microstructure (SEM: Scanning Electron Microscope) Test

[0106] Figure 3 (a) is the SEM analysis result of the Al-5Li alloy powder raw material of Example 1, Figure 3 (b) is the SEM analysis result of the modified Al-5Li alloy powder (AL-1) of Example 1.

[0107] like Figure 3 As shown in (a), the surface of Al-5Li alloy powder is rough and severely oxidized. Figure 3As shown in (b), the surface of the modified Al-5Li alloy powder (AL-1) obtained after alcohol reagent pretreatment and organic phosphate + titanate passivation treatment is smooth and can form a protective layer.

[0108] Test Example 4: Compatibility Test

[0109] This test example examined the compatibility of the Al-5Li alloy powder before and after the modification treatment in Example 1.

[0110] Test method: Use a stirring paddle to mix the metal powder with liquid adhesive, plasticizer, oxidant and other components in a certain proportion and stir them evenly. Then place the powder in an oven at 50-65℃ to form and solidify it.

[0111] Test results: see Figure 4 ,in, Figure 4 (a) shows the curing effect of the Al-5Li alloy powder raw material in Example 1 when used in the propellant. Figure 4 (b) Curing effect of modified Al-5Li alloy powder (AL-1) in Example 1 in propellant.

[0112] In order to verify the compatibility of the modified aluminum-lithium alloy fuel prepared by the present invention in solid propellants, the curing effects of a certain formula propellant containing Al-5Li alloy powder before and after modification were compared. Figure 4 As shown in (a), the propellant containing the original Al-5Li alloy powder cannot be solidified, while the Al-5Li alloy powder (AL-1) obtained after the modified treatment is used in the propellant of the same formula and the solidified cross section is dense and defect-free ( Figure 4 b), indicating that the compatibility of the Al-5Li alloy powder in solid propellants was significantly improved after alcohol reagent pretreatment and organic phosphate + titanate passivation treatment.

[0113] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make slight changes or modifications to equivalent embodiments of the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a high temperature resistant and stabilized modified aluminum-lithium alloy powder, characterized in that: The following steps are involved: S1: adding aluminum-lithium alloy powder to an alcohol reagent, stirring and dispersing the mixture, and filtering and drying the mixture to obtain a pretreated powder; S2: adding an organic phosphate and a titanate reagent into an organic solvent and performing ultrasonic dissolution and dispersion to obtain an organic mixed solution; S3: adding the pretreated powder obtained in step S1 to the organic mixed solution obtained in step S2, stirring and reacting until the solvent is completely evaporated, and then vacuum drying to obtain a modified aluminum-lithium alloy powder.

2. The preparation method according to claim 1, characterized in that In step S1, the stirring and dispersing time is 30 to 60 minutes.

3. The preparation method according to claim 1, characterized in that In step S3, the stirring reaction temperature is 70-90°C.

4. The preparation method according to claim 1-3, characterized in that The aluminum-lithium alloy powder is spherical aluminum-lithium alloy powder, the lithium content in the aluminum-lithium alloy powder is 5%-10%, and the median diameter is 2-50 μm.

5. The preparation method according to claims 1-3, characterized in that The mass ratio of the aluminum-lithium alloy powder in step S1 to the organic phosphate in step S2 is 1:0.01-1:0.03; the mass ratio of the aluminum-lithium alloy powder in step S1 to the titanate in step S2 is 1:0.01-1:0.

03.

6. The preparation method according to claims 1-3, characterized in that In step S1, the alcohol reagent is selected from any one of methanol, ethanol, isopropanol, pentaerythritol, allyl alcohol, propylene glycol, and ethylene glycol, or a mixture of two or more thereof.

7. The preparation method according to claims 1-3, characterized in that In step S2, the organic phosphate is selected from any one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, tetraethyl pyrophosphate, tris(2-chloroethyl) phosphate, tributyl phosphate, diphenyl isooctyl phosphate, tricresyl phosphate, and triallyl phosphate, or a mixture of two or more thereof.

8. The preparation method according to claims 1-3, characterized in that In step S2, the titanate reagent is selected from any one of chloroisopropyl tris (dioctyl phosphate) titanate, isopropyl tris (stearoyl) titanate, di (dioctyl pyrophosphate) oxyacetic acid titanate, di (dioctyl phosphite) tetraisopropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, trifluoroacetyl titanate, and titanate-siloxane, or a mixture of two or more thereof.

9. The preparation method according to claims 1-3, characterized in that In step S2, the organic solvent is selected from any one of petroleum ether, diethyl ether, ethyl acetate, and N,N-dimethylformamide, or a mixture of two or more thereof.

10. A high temperature resistant and stabilized modified aluminum-lithium alloy powder, characterized in that: The modified aluminum-lithium alloy powder is prepared by the preparation method described in any one of claims 1 to 9.

11. The modified aluminum-lithium alloy powder according to claim 10, characterized in that The content of the organic phosphate + titanate modified layer is ≤ 3.0 wt.% of the mass of the aluminum-lithium alloy powder.

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