High-stability laser micro-propulsion material resistant to environmental storage and exposure as well as preparation method and application of high-stability laser micro-propulsion material

Abstract

The invention discloses a high-stability laser micro-propulsion material resistant to environmental storage and exposure as well as preparation and application of the high-stability laser micro-propulsion material. The material is a copper-iron bimetal organic framework material, the molar ratio of a copper element to an iron element is (4: 1)-(20: 1), and an organic ligand is an aromatic polycarboxylic acid ligand; the retention rate of the laser ablation efficiency eta is not lower than 70% after the laser ablation material is stored in an air or water environment for 5-7 days. The preparation method of the material comprises the steps of reaction of copper salt, iron salt and organic ligand in a solvent, solvent replacement and drying, and is mild in process and low in cost. The Cu-Fe bimetallic nodes are constructed and the proportion of the Cu-Fe bimetallic nodes is regulated and controlled, so that the structural stability and the laser ablation performance of the material are synergistically improved, the key problem that the performance of an existing propellant is degraded under the exposure of a humid and water environment is solved, and stable and reliable thrust can still be output after long-term storage or accidental exposure; the method has an important application prospect in a micro-nano satellite propulsion system.

Description

Technical Field

[0001] This invention belongs to the field of laser micro-propulsion propellant material preparation technology, specifically relating to a highly stable laser micro-propulsion material resistant to environmental storage and exposure, its preparation method and application. Background Technology

[0002] Laser micropropulsion (LMP) is a micropropulsion technology that uses pulsed lasers to irradiate the surface of a solid propellant and obtain thrust through the recoil of a transient high-temperature, high-pressure plasma plume. It has advantages such as simple structure, short response time, and precise thrust control, and has been considered an important candidate propulsion method for missions such as attitude control, formation flying, and fine on-orbit operation of micro and nano satellites.

[0003] In practical engineering applications, solid propellants for laser micro-propulsion do not only operate in vacuum orbit environments. During material synthesis, encapsulation, ground storage, transportation, satellite integration, environmental testing, and long-term standby before launch, they inevitably experience exposure to atmospheric environments and even high-humidity environments. For some applications, such as miniaturized rapid-response satellites and reusable spacecraft, the propellant may also face short-term contact with water or high-humidity condensation conditions. Therefore, laser micro-propulsion propellants not only need to possess excellent transient laser ablation performance but must also maintain structural stability and consistent propulsion performance in long-term non-vacuum environments.

[0004] Existing solid propellants for laser micropropulsion mainly include polymer propellants, single-element material propellants, and their composite systems. Polymer propellants typically have a lower ablation threshold and a higher impulse coupling coefficient. C m However, under laser irradiation, excessive pyrolysis and deep ablation are prone to occur, resulting in excessively high single-pulse ablation mass and low specific impulse. I sp The specific impulse is too low to meet the requirements of high-precision propulsion. Although single metal or carbon-based propellants can achieve high specific impulse, their small particle size and high surface energy make them prone to agglomeration, oxidation, or changes in surface state during storage and use. This leads to unstable laser absorption behavior and ablation modes, and the propulsion performance degrades significantly with storage time.

[0005] To improve light absorption and propulsion performance, existing research has attempted to introduce metal-organic frameworks (MOFs) as laser micro-propulsion propellants or their functional components (patent numbers: ZL202310792280.3, 202310790884.4). MOFs possess advantages such as strong structural designability, large specific surface area, and high photo-thermal conversion efficiency, demonstrating certain advantages in short-term laser propulsion tests. However, existing MOF systems used for laser propulsion mostly employ single metal nodes, and their crystal structure relies on coordination bonds for maintenance. In humid air or water environments, coordination bonds are prone to hydrolysis, leading to framework structure collapse, pore blockage, or morphological damage. This structural degradation does not immediately result in complete failure, but it significantly alters the laser energy absorption and heat conduction paths of the material, causing the ablation behavior to change from "rapid, uniform ablation" to "local melting or incomplete ablation," ultimately leading to… C m , I sp as well as or The irreversible decline.

[0006] Based on this, it is important to note that existing solid propellants for laser micro-propulsion (especially emerging MOF-based materials) are prone to collapse or deterioration of their microstructure due to coordination bond hydrolysis after long-term exposure to air, high humidity, or even short-term water environments. This leads to instability in laser ablation behavior and impaired propulsion performance. C m , I sp as well as or To address the problem of irreversible degradation, this paper proposes a highly stable laser micro-propulsion material and its preparation method that is resistant to environmental storage and exposure. This material maintains a high degree of consistency between its laser ablation behavior and LMP performance even after undergoing material synthesis, ground storage, environmental testing, and long-term standby before launch. This is of great significance for improving the on-orbit reliability of micro- and nano-satellites, extending the ground storage life of propulsion systems, and expanding the applicability of laser micro-propulsion technology under complex environmental conditions. It is also a key technical problem that urgently needs to be solved in the field of laser micro-propulsion. Summary of the Invention

[0007] One of the objectives of this invention is to provide a highly stable laser micro-propulsion material that is resistant to environmental storage and exposure.

[0008] The second objective of this invention is to provide a method for preparing a highly stable laser micro-propulsion material that is resistant to environmental storage and exposure.

[0009] The third objective of this invention is to provide an application of a highly stable laser micro-propulsion material in storage in air, humid or water environments.

[0010] One of the technical solutions adopted by this invention is to provide a highly stable laser micro-propulsion material that is resistant to environmental storage and exposure. The highly stable laser micro-propulsion material is a copper-iron bimetallic organic framework material; in the copper-iron bimetallic organic framework material, the molar ratio of copper to iron is 4:1-20:1; the organic ligand is an aromatic polycarboxylic acid ligand; after being stored in an air or water environment for 5-7 days, the laser ablation efficiency of the highly stable laser micro-propulsion material is [not specified]. or The retention rate should be no less than 70%.

[0011] The overall concept and inventive mechanism of this invention are as follows: This invention provides a highly stable laser micro-propulsion material. By introducing a specific combination of bimetallic nodes and precisely controlling their ratio, the structural stability and laser propulsion performance of the material under long-term exposure to air or water environments are simultaneously improved without weakening the laser ablation performance. The laser ablation mode and energy coupling behavior are maintained in the same way as the initial state, thereby solving the problem of performance degradation of existing propellants in actual storage, transportation and application.

[0012] In the extreme conditions of laser micro-propulsion, characterized by high power density and transient energy input, the type and proportion of metal nodes not only determine the environmental stability of the material but also significantly affect its optical absorption characteristics, photothermal conversion efficiency, and ablation kinetics. Specifically, after exposure to air or water, some materials, despite not showing significant macroscopic structural collapse, can experience a decrease in laser absorption efficiency and a change in the ablation process from uniform ablation to localized melting or incomplete ablation, thus leading to… C m , I sp as well as or The propulsion performance parameters have significantly decreased.

[0013] This invention is based on previous research into various bimetallic combinations. While other bimetallic combinations such as Cu-Zn, Cu-Mn, Cu-Ni, and Cu-Co can improve the environmental stability of materials to some extent under normal conditions, exposure to air or water often leads to adverse effects in laser micro-propulsion applications, such as decreased light absorption, uneven ablation behavior, or fluctuations in propulsion performance, making it difficult to achieve the expected comprehensive technical effects. After extensive experimentation and screening, this invention determines to use a Cu-Fe bimetallic MOF propellant system, wherein Cu... 2+ The nodes are primarily responsible for maintaining the light absorption capacity and photothermal conversion efficiency of the original MOF framework, while Fe... 3+The introduction of FeO effectively suppresses the hydrolysis of carboxylic acid ligands in air or water environments by forming stronger Fe-O coordination bonds, and maintains uniform and repeatable energy release behavior during laser ablation, thereby achieving simultaneous improvement in the stability of the frame structure and the performance of laser propulsion.

[0014] Furthermore, the Cu / Fe molar ratio has a decisive influence on the structural stability of the propellant and the performance of laser micro-propulsion. Studies have found that when the Fe content is too low, although the material retains good photothermal properties, its resistance to hydrolysis is insufficient, and its ablation behavior is easily altered after environmental exposure. Conversely, when the Fe content is too high, it may disturb the electronic structure and energy deposition process of the original Cu-BTC framework, leading to uneven laser ablation and thus weakening propulsion performance. This invention controls the molar ratio of copper to iron within the range of 4:1-20:1, which not only effectively improves the structural stability of the material in air and water environments, but more importantly, maintains the consistency of the propellant's laser ablation behavior and LMP performance output before and after environmental exposure. After being stored in an air or water environment for 5 to 7 days, the laser ablation efficiency of the described high-stability laser micro-propulsion material is significantly improved. or The retention rate should be no less than 70%.

[0015] Furthermore, in the raw materials of the copper-iron bimetallic organic framework material, the copper salt and iron salt are independently selected from the corresponding nitrates or chloride hydrates of the metals; the mass ratio of the copper salt to the organic ligand is (1-2):1.

[0016] Furthermore, the organic ligand is selected from one of tricresylbenzene, phthalic acid, and dihydroxyterephthalic acid.

[0017] Furthermore, after the highly stable laser micro-propulsion material was stored in air at 25±2℃ and a relative humidity of 60%±5% for 7 days, the impulse coupling coefficient... C m The retention rate is 84.9%-99.5%, and the specific impulse is... I sp Retention rate is 85.5%-100%; laser ablation efficiency or The retention rate was 73.5%-98.6%.

[0018] Furthermore, after the highly stable laser micro-propulsion material was immersed in water for 5 days, the impulse coupling coefficient... C m The retention rate was 86.1%-98.4%, and the specific impulse was... I sp The retention rate is 85.0%-99.3%; laser ablation efficiency or The retention rate was 76.4%-97.7%.

[0019] Furthermore, studies on the comprehensive structural stability, light absorption characteristics, and laser ablation kinetics of laser micro-propulsion materials revealed an optimal Cu / Fe molar ratio. When the Cu / Fe molar ratio is approximately 8:1–15:1, Fe… 3+ The introduction of this material allows for the formation of a continuous and stable coordination protection network without compromising the original photothermal conversion advantages, ensuring the propellant maintains framework integrity and consistent laser ablation behavior before and after environmental exposure. While deviations from this ratio may improve individual performance indicators, they cannot simultaneously meet the comprehensive requirements of environmental stability and LMP performance maintenance. Therefore, controlling the molar ratio of copper to iron in the copper-iron bimetallic organic framework material to 8:1-15:1 can improve laser ablation efficiency. or The retention rate is above 90%. More preferably, the molar ratio of copper to iron is 12:1. In this case, the bimetallic node can still maintain optimal crystal structure integrity and laser ablation performance after the framework material is exposed to air or water. After being stored in air at 25±2℃ and 60%±5% relative humidity for 7 days, the impulse coupling coefficient... C m The retention rate was 99.5%, and the specific impulse was... I sp The retention rate was 98.8%; the laser ablation efficiency was... or The retention rate was 98.2%; after immersion in water for 5 days, the impulse coupling coefficient... C m The retention rate was 98.4%, and the specific impulse was... I sp The retention rate was 99.3%; the laser ablation efficiency was... or With a retention rate of 97.7%, it has the best overall performance.

[0020] The second objective of this invention is to provide a method for preparing a highly stable laser micro-propulsion material according to one objective of this invention, comprising the following steps: S1. Weigh out copper salt, iron salt, organic ligand and solvent in proportion, and mix until the solid particles are completely dissolved to obtain a mixture; S2. React the mixture at a certain temperature for a certain time to obtain the product; S3. The product is subjected to solvent replacement, followed by vacuum drying and cooling to obtain a highly stable laser micro-propulsion material.

[0021] Further, in step S1, the solvent is selected from one or more combinations of N,N-dimethylformamide, methanol, ethanol, and deionized water.

[0022] Further, in step S2, the reaction temperature is 20-140 °C, and the reaction time is 1-48 h. Specifically, the reaction is carried out at room temperature or under heating conditions; the heating method includes one of water bath heating, laser heat treatment, and microwave heat treatment.

[0023] Furthermore, in step S3, solvent replacement includes: performing multiple replacements using one or more of anhydrous ethanol, water, and N,N-dimethylformamide, depending on the solubility of the product in different solvents.

[0024] The third objective of this invention is to provide an application of a highly stable laser micro-propulsion material as described in one objective of this invention or a highly stable laser micro-propulsion material prepared by the preparation method described in another objective of this invention. This highly stable laser micro-propulsion material exhibits high laser ablation efficiency after exposure to air or water environments. or The retention rate should be no less than 70%.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention provides a highly stable laser micro-propulsion material resistant to environmental storage and exposure, and its preparation method. By constructing Cu-Fe bimetallic nodes and precisely controlling their molar ratio, this invention achieves synergistic optimization and simultaneous improvement of environmental stability and laser propulsion performance in metal-organic framework materials, effectively solving the common industry problem of poor environmental stability of traditional MOF propellants and the deterioration of laser ablation performance often caused by conventional stability improvement schemes. This material can maintain its complete crystal morphology and laser ablation characteristics even after air storage or short-term immersion in water. Its core propulsion performance parameter, specific impulse (... I sp ), impulse coupling coefficient ( C m ) and ablation efficiency ( or The retention rates of the material are significantly better than those of existing technologies. Experiments show that, under optimal conditions, the ablation efficiency of the material is significantly higher after 7 days of storage in air or 5 days of immersion in water. or The retention rate is still over 97%, overcoming the inherent defects of existing polymers, single metals and simple composite propellants that suffer from rapid performance degradation in non-vacuum environments.

[0026] (2) The preparation method provided by this invention is mild, simple, and uses low-cost raw materials, avoiding complex high-temperature, high-pressure, or post-modification processes. It has excellent potential for engineering scale-up and application promotion. Compared with other bimetallic systems, the Cu-Fe combination used in this invention exhibits a unique synergistic effect during laser ablation, which not only ensures the structural robustness of the framework but also ensures the uniform and stable generation of the plasma plume, thereby achieving excellent propulsion performance repeatability and reliability. This invention provides a key laser micro-propulsion material that can be stably stored in the ground environment throughout its entire lifecycle, withstands accidental exposure, and exhibits highly consistent performance for missions such as micro-nano satellites, formation flying, and on-orbit precision operations. It has important strategic significance for improving the environmental adaptability, mission reliability, and on-orbit lifespan of spacecraft propulsion systems. Attached Figure Description

[0027] Figure 1 The images show a comparison of SEM images of the laser micro-propulsion materials prepared in Example 1 and Comparative Example 1 after being stored continuously in air for 7 days; where (A) is the sample of Comparative Example 1; and (B) is the sample of Example 1. Figure 2 The images show the SEM images of the laser micro-propulsion materials prepared in Example 1 and Comparative Example 1 after immersion in water for 6 hours; wherein, (A) the initial morphology of the sample in Comparative Example 1; (B) the sample in Comparative Example 1 after immersion; (C) the initial morphology of the sample in Example 1; and (D) the sample in Example 1 after immersion. Figure 3 SEM images of the laser micro-propulsion material prepared in Example 1 of the invention after immersion in water for a certain period of time; wherein, (A) is after immersion for 5 days; (B) is after immersion for 6 days. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides a highly stable laser micro-propulsion material and its preparation method, the preparation method comprising the following steps: Step 1: Weigh out copper salt, iron salt, organic ligand, and solvent according to the specified ratio, and mix until the solid particles are completely dissolved to obtain a mixture; the molar ratio of copper to iron in the copper and iron salts is 4:1-20:1; the copper and iron salts are independently selected from the corresponding metal nitrates or chloride hydrates; the mass ratio of copper salt to organic ligand is (1-2):1; the organic ligand is selected from one of tricresylbenzene, phthalic acid, and dihydroxyterephthalic acid; the solvent is selected from one or more combinations of N,N-dimethylformamide, methanol, ethanol, and deionized water.

[0030] Step 2: React the mixture at 20-140℃ for 1-48 hours to obtain the product; the reaction can be carried out at room temperature or under heating conditions, and the heating method includes one of water bath heating, laser heat treatment, and microwave heat treatment.

[0031] Step 3: Based on the solubility of the product in different solvents, multiple substitutions are performed using one or more of anhydrous ethanol, water, and N,N-dimethylformamide, followed by vacuum drying and cooling to obtain the highly stable laser micro-propulsion material.

[0032] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0033] Example 1 This embodiment provides a method for preparing a highly stable laser micro-propellant material. The molar ratio of the metal salts required for the synthesis of this highly stable laser micro-propellant material is 20:1 (copper nitrate (hydrated):ferric nitrate (hydrated)), named CuFe-MOF-20. The synthesis method of this propellant is as follows: 4 mmol of copper nitrate (hydrated), 0.2 mmol of ferric nitrate (hydrated), and 0.735 g of benzoic acid are weighed using a chemical balance. 12.5 mL of ethanol and 12.5 mL of deionized water are pipetted in. The reagents are stirred thoroughly until the solid particles are completely dissolved and the solution is clear. The solution is then transferred to a 50 mL beaker, and the mouth of the beaker is covered with plastic wrap to prevent dust from entering. The reaction is allowed to proceed at room temperature for 24 hours. After the reaction is complete, the product is subjected to solvent replacement with ethanol three times, with each replacement occurring 12 hours apart. The resulting blue powder is dried and cooled to obtain the solid propellant CuFe-MOF-20.

[0034] Example 2 Compared with Example 1, the difference is that the amount of ferric nitrate (hydrated) was adjusted to 0.26 mmol, the molar ratio of copper to iron was 15:1, and the other preparation conditions were the same as in Example 1. The solid propellant obtained in Example 4 was named CuFe-MOF-15.

[0035] Example 3 Compared with Example 1, the difference is that the amount of ferric nitrate (hydrated) was adjusted to 0.33 mmol, the molar ratio of copper to iron was 12:1, and the other preparation conditions were the same as in Example 1. The solid propellant obtained in Example 3 was named CuFe-MOF-12.

[0036] Example 4 Compared with Example 1, the difference is that the amount of ferric nitrate (hydrated) was adjusted to 0.5 mmol, the molar ratio of copper to iron was 8:1, and the other preparation conditions were the same as in Example 1. The solid propellant obtained in Example 2 was named CuFe-MOF-8.

[0037] Example 5 Compared to Example 1, the difference lies in the amount of hydrated ferric nitrate being adjusted to 1 mmol, the molar ratio of copper to iron being 4:1, and the remaining preparation conditions being the same as in Example 1. The solid propellant obtained in Example 5 was named CuFe-MOF-4.

[0038] Comparative Example 1 (Cu single metal) This comparative example provides a solid propellant prepared using copper monometallic salt. The metal salt required for the synthesis of this solid propellant is hydrated copper nitrate. The synthesis method of this propellant is as follows: 4 mmol of hydrated copper nitrate and 0.735 g of benzoic acid were weighed using a chemical balance. 12.5 mL of ethanol and 12.5 mL of deionized water were pipetted into the solution. The above reagents were stirred thoroughly until the solid particles were completely dissolved and the solution was clear. Then, the solution was transferred to a 50 mL beaker, and the mouth of the beaker was covered with plastic wrap to prevent dust from entering. The reaction was allowed to stand at room temperature for 24 h. After the reaction was completed, the product was subjected to solvent replacement with ethanol three times, with each replacement at 12 h intervals. The resulting blue powder was dried and cooled to obtain the solid propellant Cu-MOF.

[0039] Comparative Example 2 (Cu-Mn Bimetallic System) This comparative example provides a solid propellant prepared using a copper-manganese bimetallic system to compare the effects of different bimetallic combinations on stability and laser propulsion performance. The specific preparation method is as follows: 4 mmol of hydrated copper nitrate and 1 mmol of hydrated manganese nitrate were weighed using a chemical balance, and 0.735 g of benzotricarboxylic acid was weighed. 12.5 mL of ethanol and 12.5 mL of deionized water were added. The remaining preparation steps were the same as in Example 1. The resulting solid propellant was named CuMn-MOF-4.

[0040] Comparative Example 3 (Cu-Co Bimetallic System) This comparative example provides a solid propellant prepared using a copper-cobalt bimetallic system. The specific preparation method is as follows: 4 mmol of hydrated copper nitrate and 1 mmol of hydrated cobalt nitrate were weighed, and 0.735 g of tricresyl benzene, 12.5 mL of ethanol and 12.5 mL of deionized water were added. The remaining steps were the same as in Example 1. After reaction, solvent replacement and drying, a solid propellant was obtained and named CuCo-MOF-4.

[0041] Comparative Example 4 (Cu-Ni Bimetallic System) This comparative example provides a solid propellant prepared using a copper-nickel bimetallic system. The specific preparation method is as follows: 4 mmol of hydrated copper nitrate and 1 mmol of hydrated nickel nitrate were weighed, and 0.735 g of tricresyl benzene, 12.5 mL of ethanol and 12.5 mL of deionized water were added. The remaining steps were the same as in Example 1. After reaction, solvent replacement and drying, a solid propellant was obtained, named CuNi-MOF-4.

[0042] Comparative Example 5 (Cu-Al Bimetallic System) This comparative example provides a solid propellant prepared using a copper-aluminum bimetallic system. The specific preparation method is as follows: 4 mmol of hydrated copper nitrate and 1 mmol of hydrated aluminum nitrate were weighed, and 0.735 g of tricresyl benzene, 12.5 mL of ethanol and 12.5 mL of deionized water were added. The remaining steps were the same as in Example 1. After reaction, solvent replacement and drying, a solid propellant was obtained and named CuAl-MOF-4.

[0043] Stability and LMP performance testing Based on the aforementioned material structure design and metal node control mechanism, in order to further verify the comprehensive influence of different metal systems and their ratios on the environmental stability of solid propellants and the performance of laser micropropulsion (LMP), this invention systematically carried out LMP performance tests under vacuum conditions, and focused on examining the structural retention ability and propulsion performance degradation behavior of the samples after exposure to air and water environments.

[0044] (I) LMP performance testing and baseline condition determination under vacuum conditions In LMP technology, the impulse coupling coefficient ( C m ), specific impulse ( I sp ) and laser ablation efficiency ( or LMP (Laser Propellant Performance) is a key indicator for evaluating propellant performance. This invention employs a torsion pendulum device to systematically test the laser micropropellant materials prepared in each embodiment and comparative example under a controlled vacuum environment. First, taking the single-metal Cu-MOF of Comparative Example 1 as an example, the LMP performance under different vacuum pressure conditions was compared and tested. The test results are shown in Table 1.

[0045] Table 1. Comparison of LMP performance of Cu-MOF prepared in Comparative Example 1 under different pressures.

[0046] As can be seen from Table 1, as the ambient pressure gradually decreases from normal pressure, the propellant's... C m , I sp and or All parameters exhibited a trend of initial increase followed by stabilization, reaching an equilibrium state around 15 kPa. Under this pressure condition, the propellant can achieve a high impulse output while avoiding plasma plume diffusion losses due to excessively low pressure. Therefore, all subsequent LMP performance tests in all embodiments and comparative examples were conducted under a 15 kPa vacuum condition to ensure data comparability.

[0047] (II) LMP performance of different metal systems under vacuum conditions Table 2 shows the LMP performance test results of the laser micro-propulsion materials of each embodiment and comparative example under vacuum conditions, compared under the same test conditions.

[0048] Table 2. Comparison of LMP performance of different solid propellants under 15 kPa vacuum conditions.

[0049] The results in Table 2 show that Introducing different metal nodes and their proportions significantly affects propellant performance. In the Cu-Fe bimetallic system, the propellant performance of CuFe-MOF-20 in Example 1 is similar to that of the monometallic Cu-MOF in Comparative Example 1, indicating that at low Fe content, its control over laser ablation behavior and energy coupling is still limited and insufficient to significantly improve overall LMP performance. However, CuFe-MOF-12 exhibits significantly better propellant performance than the monometallic Cu-MOF. C m , I sp and or The LMP values ​​reached 185 μN / W, 567 s, and 51.40%, respectively, the highest among all samples, indicating that the light absorption-photothermal conversion and ablation kinetics of the material were synergistically optimized after the introduction of appropriate Fe content. In contrast, when the Fe content was further increased (CuFe-MOF-4), its LMP performance decreased significantly. C m , I sp and orThe performance of Cu-Fe was significantly lower than that of Cu-MOF-12. This indicates that the introduction of Fe is not necessarily better the more it is added; only within a reasonable ratio can efficient and uniform laser ablation behavior be maintained while preserving the integrity of the framework structure. Furthermore, compared to other bimetallic systems such as Cu-Mn, Cu-Co, Cu-Ni, and Cu-Al used in Examples 2-5, their overall LMP performance was significantly lower than that of the Cu-Fe bimetallic system, further demonstrating the significant system advantages of the Cu-Fe metal combination under laser micro-propulsion conditions.

[0050] (iii) Structural stability and LMP performance retention after exposure to air environment To simulate the air exposure conditions that propellants may experience in actual engineering applications, each sample was stored continuously for 7 days in a standard atmospheric environment (25±2℃, relative humidity 60%±5%), and then its microstructure and LMP performance were tested.

[0051] like Figure 1 As shown, the original regular crystal morphology of the single-metal Cu-MOF propellant prepared in Comparative Example 1 gradually collapsed and broke during air storage, indicating poor framework structure stability. In contrast, the Cu-Fe bimetallic system sample maintained a more complete crystal morphology under the same conditions, demonstrating significantly better environmental stability.

[0052] Further LMP performance test results are shown in Table 3.

[0053] Table 3. Comparison of LMP performance of various solid propellants after 7 days of continuous storage in air.

[0054] It can be seen from Table 3 above that After being stored in air for 7 days, the single-metal Cu-MOF prepared in Comparative Example 1 showed... C m , I sp and or The impulse coupling coefficients decreased to 122 μN / W, 486 s, and 29.05%, respectively, showing significant performance degradation. In contrast, the impulse coupling coefficients of the bimetallic laser micro-propulsion materials prepared in Examples 1-5 were significantly lower. C m The retention rate is 84.9%-99.5%, and the specific impulse is... I sp Retention rate is 85.5%-100%; laser ablation efficiency or The retention rate was 73.5%-98.2%.

[0055] Furthermore, the performance stability of samples with different Cu-Fe ratios varied to some extent. In Examples 2-4, the retention rate of various properties was higher when the copper / iron molar ratio was controlled within the range of 8:1-15:1. Among them, the CuFe-MOF-12 (copper / iron molar ratio of 12:1) prepared in Example 3 still maintained 184 μN / W after exposure to air. C m 560s I sp And 50.49% or It is almost identical to its initial performance, demonstrating optimal performance retention.

[0056] (iv) Structural stability and LMP performance retention after exposure to aquatic environment Under more demanding aquatic conditions, each sample was completely immersed in deionized water for a certain period of time to assess its resistance to hydrolysis and retention of propulsion performance.

[0057] Figure 2 SEM morphology results showed that the Cu-MOF prepared in Comparative Example 1 underwent significant morphological changes after only 6 hours of immersion in water, while the sample from Example 1 maintained stable morphology. Furthermore, Figure 3 SEM morphology results showed that the CuFe-MOF-20 sample prepared in Example 1 retained its original octahedral crystal structure after being immersed in water for 5 consecutive days, and structural collapse only occurred after 6 days. Compared with the single-metal Cu-MOF propellant of Comparative Example 1, CuFe-MOF-20 exhibited better structure retention in an aqueous environment, indicating that the introduction of Fe... 3+ It helps to suppress framework hydrolysis.

[0058] It should be noted that there are still significant differences in structural stability and laser ablation behavior among samples with different Cu-Fe ratios. Although CuFe-MOF-20 of Example 1 can maintain its macroscopic crystal morphology in an aqueous environment, its laser ablation uniformity and propulsion performance retention are still significantly lower than those of CuFe-MOF-12 prepared in Example 3, indicating that structural integrity alone is not sufficient to guarantee excellent LMP performance output.

[0059] As shown in Table 4, after exposure to an aquatic environment, CuFe-MOF-12 exhibits [results in...]. C m , I sp and orThe performance remained high, exhibiting the best overall performance among all samples. In contrast, while CuFe-MOF-20 and other formulations showed improvement over the monometallic system, they still lagged behind in terms of propulsion stability. These results further demonstrate that, under the condition of controlling the copper / iron molar ratio at 12:1, the Cu-Fe bimetallic system can ensure the optimal synergistic effect between structural stability and LMP performance.

[0060] Table 4. Comparison of LMP performance of various solid propellants after 5 days in an aqueous environment.

[0061] A systematic comparison of the structure and laser micro-propulsion performance of different metal systems and propellant ratios prepared in each embodiment and comparative example under initial conditions, air environment, and water environment exposure clearly shows that not all bimetallic combinations or arbitrary metal ratios can achieve a synergistic improvement in stability and propulsion performance under laser micro-propulsion conditions. Only the specific Cu-Fe metal combination used in Examples 1-5, under reasonable ratio conditions, can effectively suppress environmental hydrolysis while maintaining the advantages of MOF framework in light absorption and photothermal conversion, and maintain stable and repeatable laser ablation behavior before and after long-term environmental exposure. Among them, when the Cu / Fe molar ratio is controlled within the range of 8:1-15:1, the propellant exhibits better and more stable comprehensive performance in key indicators such as impulse coupling coefficient, specific impulse, and energy utilization efficiency, and the comprehensive performance is optimal when the ratio is 12:1.

[0062] In summary, the specific Cu-Fe bimetallic organic framework material and its formulation provided by this invention successfully solve the key problem of balancing environmental stability and high efficiency in laser micro-propulsion materials, providing a novel propellant solution for spacecraft such as micro- and nano-satellites that can reliably operate in harsh environments.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A highly stable laser micro-propulsion material resistant to environmental storage and exposure, characterized in that, The highly stable laser micro-propulsion material is a copper-iron bimetallic organic framework material; in the copper-iron bimetallic organic framework material, the molar ratio of copper to iron is 4:1-20:1; the organic ligand is an aromatic polycarboxylic acid ligand; after being stored in an air or water environment for 5 to 7 days, the laser ablation efficiency of the highly stable laser micro-propulsion material is [not specified]. η The retention rate should be no less than 70%.

2. The high-stability laser micro-propulsion material according to claim 1, characterized in that, In the raw materials of the copper-iron bimetallic organic framework material, the copper salt and iron salt are independently selected from the corresponding nitrates or chloride hydrates of the metals; the mass ratio of the copper salt to the organic ligand is (1-2):

1.

3. The high-stability laser micro-propulsion material according to claim 1, characterized in that, The organic ligand is selected from one of benzotricarboxylic acid, phthalic acid, and dihydroxyterephthalic acid.

4. The high-stability laser micro-propulsion material according to claim 1, characterized in that, The highly stable laser micro-propulsion material was stored in air at 25±2℃ and 60%±5% relative humidity for 7 days, and the impulse coupling coefficient... C m The retention rate is 84.9%-99.5%, and the specific impulse is... I sp Retention rate is 85.5%-100%; laser ablation efficiency η The retention rate was 73.5%-98.6%.

5. The high-stability laser micro-propulsion material according to claim 1, characterized in that, After the highly stable laser micro-propulsion material was immersed in water for 5 days, the impulse coupling coefficient was... C m The retention rate was 86.1%-98.4%, and the specific impulse was... I sp The retention rate is 85.0%-99.3%; laser ablation efficiency η The retention rate was 76.4%-97.7%.

6. The method for preparing a highly stable laser micro-propulsion material according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh out copper salt, iron salt, organic ligand and solvent in proportion, and mix until the solid particles are completely dissolved to obtain a mixture; S2. React the mixture at a certain temperature for a certain time to obtain the product; S3. The product is subjected to solvent replacement, followed by vacuum drying and cooling to obtain a highly stable laser micro-propulsion material.

7. The preparation method according to claim 6, characterized in that, In step S1, the solvent is selected from one or more combinations of N,N-dimethylformamide, methanol, ethanol, and deionized water.

8. The preparation method according to claim 6, characterized in that, In step S2, the reaction temperature is 20-140℃ and the reaction time is 1-48 h.

9. The preparation method according to claim 6, characterized in that, In step S3, solvent replacement includes: based on the solubility of the product in different solvents, performing multiple replacements using one or more of anhydrous ethanol, water, and N,N-dimethylformamide.

10. The application of a highly stable laser micro-propulsion material according to any one of claims 1-5 or a highly stable laser micro-propulsion material prepared by the preparation method according to any one of claims 6-9, characterized in that, The high-stability laser micro-propulsion material exhibits high laser ablation efficiency after exposure to air or water environments. η The retention rate should be no less than 70%.

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