Method for simulating rapid prototyping of lunar soil through microwave-assisted microorganism induced precipitation solidification

Abstract

The invention belongs to the technical field of simulated lunar soil reinforcement, and particularly relates to a microwave-assisted rapid prototyping method for simulated lunar soil through microorganism induced precipitation and solidification. The method comprises the following steps: directly mixing simulated lunar soil with ground calcium chloride powder to obtain a powder mixture; screening urease-producing flora from soil by using a culture medium containing urea and nutrient substances to obtain a microbial agent; the microbial agent and the powder mixture are mixed, and mixed paste is obtained; the paste is subjected to microwave treatment, and rapid solidification of the sandy soil is achieved. The method provided by the invention not only can solve the problem of high water consumption in the traditional pouring process, but also can shorten the curing time of the simulated lunar soil, and the method has low demand for urea and nutrient substances, and can be suitable for soil curing in the lunar environment with shortage of resources.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of simulated lunar soil reinforcement, and particularly relates to a method for microwave-assisted microbial-induced precipitation solidification rapid forming of simulated lunar soil. BACKGROUND

[0002] The lunar surface environment is extremely harsh, with a large diurnal temperature difference, high vacuum, strong radiation, and frequent micro-meteorite impacts. Therefore, when constructing infrastructure or establishing a base on the lunar surface, it is necessary to develop a rapid, efficient, and controllable energy and resource consumption ground reinforcement and protection technology. Microbial-induced carbonate precipitation (MICP) technology is a new bio-mineralization reinforcement method that promotes the hydrolysis of urea to produce carbonate ions through microbial metabolism, which combines with calcium ions in the environment to form carbonate precipitation, thereby cementing loose particles. The lack of cohesion between lunar soil particles and the loose structure make them highly suitable for the particle cementation mechanism of MICP technology, and have good technical application potential.

[0003] However, due to the extremely limited availability of real lunar soil samples, current research generally uses simulated lunar soil made from terrestrial basalt raw materials as the test medium to simulate its particle composition, mechanical properties, and chemical environment. The basalt sample is collected from Sandu Town, Jiande City, Zhejiang Province, China, and its main mineral composition includes augite, plagioclase, and magnesium olivine, etc. Although MICP technology shows good cementing effect, there are still significant bottlenecks in the process: on the one hand, the injection of reaction liquid (especially urea-Ca 2+ The culture medium) consumes a large amount of water resources, and water is a very valuable strategic resource on the moon. On the other hand, existing MICP treatment often relies on drying measures to accelerate the solidification process, which not only consumes a lot of energy and has low controllability, but also cannot meet the requirements of rapid construction and immediate load on the lunar surface, severely limiting the practical application feasibility of the technology in lunar base construction.

[0004] CN 106906821 A discloses a microbial sand pile forming device and method, which mixes bacterial liquid with calcium chloride and urea solution and injects it into the sand in the thin-walled cylinder through the grouting flower pipe. Some existing research directly mixes the bacterial liquid, reaction liquid, and lunar soil, which reduces the water consumption to some extent but cannot significantly shorten the time.

[0005] To address the problems of large water consumption and long preparation time, which are not suitable for practical application in lunar base construction, the present application mixes the simulated lunar soil particles and calcium chloride powder to obtain a solid powder mixture, then directly mixes the bacterial liquid with the solid powder mixture to obtain a mixed paste, and finally combines with microwave technology to realize the rapid forming of granular minerals. SUMMARY

[0006] In view of this, the purpose of this invention is to provide a method for rapid molding of simulated lunar soil using microwave-assisted microbial-induced precipitation (MICP) solidification. This method combines microwave technology with microbial-induced calcium carbonate precipitation (MICP) technology to rapidly solidify simulated lunar soil. The method provided by this invention not only solves the problem of high water consumption in traditional injection processes but also significantly shortens the solidification time of simulated lunar soil. Furthermore, this method requires relatively small amounts of urea and nutrients, making it suitable for soil solidification in resource-scarce lunar environments.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a microwave-assisted microbial-induced precipitation and solidification method for rapidly forming simulated lunar soil, comprising the following steps: The simulated lunar soil was directly mixed with ground anhydrous calcium chloride powder to obtain a powder mixture; Urease-producing bacteria were screened from soil using a culture medium containing urea and nutrients to obtain microbial agents; The microbial agent is mixed with the powder mixture to obtain a paste. Microwave treatment of the paste enables rapid solidification of simulated lunar soil.

[0008] Furthermore, the total energy of the microwave treatment was controlled at 120±5kJ, and the temperature difference at the center before and after the microwave treatment was controlled at ΔT=110±20℃.

[0009] The parameters for microwave processing are: microwave power 300~1000W, 2min~6.5min.

[0010] Preferably, the particle size of the anhydrous calcium chloride powder is ≤ .

[0011] Preferably, the simulated lunar soil is prepared from basalt powder of different particle sizes.

[0012] Preferably, the simulated lunar soil has a similar chemical composition to basalt powder.

[0013] Preferably, the mass ratio of the anhydrous calcium chloride powder to the simulated lunar soil is 1:10~20, and more preferably, the mass ratio is 1:15.

[0014] Preferably, the urease-producing bacterial group includes various microorganisms such as Bacillus pasteurellii that are capable of inducing the formation of calcium carbonate precipitation.

[0015] Preferably, the concentration of urea in the culture medium is ≤1 mol / L and the concentration of yeast extract is ≤5 g / L.

[0016] Preferably, the mass ratio of water to powder mixture in the microbial agent is 0.20 to 0.32.

[0017] Preferably, the microwave processing parameters are 700~1000W for 2~3 minutes.

[0018] Preferably, the molding and curing time is ≤6.5 min.

[0019] Preferably, the paste preparation process is carried out at room temperature (25°C).

[0020] This invention also protects a microwave-assisted microbial-induced precipitation solidification simulated lunar soil rapid prototyping material, said material being obtained using the method described above.

[0021] This invention also protects a method for microbial-induced precipitation and solidification to simulate lunar soil, comprising the following steps: The simulated lunar soil was directly mixed with ground anhydrous calcium chloride powder to obtain a powder mixture; Urease-producing bacteria were screened from soil using a culture medium containing urea and nutrients to obtain microbial agents; The microbial agent is mixed with the powder mixture to obtain a paste. The paste is dried at 40-50℃ until it is completely hardened inside, thus achieving low-moisture solidification to simulate lunar soil.

[0022] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a microwave-assisted method for the rapid molding of simulated lunar soil through microbial-induced precipitation and solidification. The method involves directly mixing simulated lunar soil with ground anhydrous calcium chloride powder to obtain a powder mixture; screening urease-producing bacteria from the soil using a culture medium containing urea and nutrients to obtain a microbial agent; mixing the microbial agent with the powder mixture to obtain a paste; and then microwave-treating the paste to achieve rapid solidification of the simulated lunar soil. This invention eliminates the step of preparing calcium chloride into a solution, avoids uneven distribution of calcium carbonate, reduces water consumption from multiple reinforcement steps in cyclic injection, and shortens the material's molding and hardening time. By directly mixing the microbial agent, simulated lunar soil, and calcium chloride powder, using only water molecules in the microbial agent as a carrier in the liquid environment, a paste is directly prepared. Simultaneously, microwave action evaporates the water molecules in the paste, achieving rapid hardening and molding, thus shortening the material's molding and hardening time. Furthermore, the recrystallization of calcium chloride under microwave action increases the density of the simulated lunar soil, and the calcium carbonate and recrystallized calcium chloride co-solidify the simulated lunar soil.

[0023] This invention allows for the autonomous determination of the mixing amount of microbial inoculant and powder mixture, thereby controlling the thickness of the calcium chloride recrystallization layer and the amount of calcium carbonate generated within a certain range. It also allows for the autonomous determination of the microwave power, thereby controlling the crystal type of calcium carbonate formed within a certain range. At 1000W, the relative content of calcite is highest, and gradually decreases as the power decreases. At 1000W, the cementing material exhibits an irregular morphology, composed of a shell-like structure and encapsulated calcite. When the power is reduced to 800W, the product displays the typical morphology of aragonite.

[0024] The quality of calcium carbonate formation in the simulated lunar soil after solidification using the method of this invention is similar to that of the dried sample, indicating that microwaves do not affect the amount of calcium carbonate formed. At the same time, the preparation time for material hardening and molding is much shorter than that required by traditional methods.

[0025] Simulated lunar soil particles are heated as a whole under microwave irradiation; however, the coefficients of thermal expansion of the components within the particles differ. During the heating process, thermal mismatch between different mineral phases can induce localized stress. Simultaneously, the characteristic that microwave absorption capacity increases with temperature can easily lead to excessive heat accumulation within the particles, resulting in central overheating. This thermo-mechanical coupling effect may cause the material to exhibit a hollow structure after microwave irradiation. In this invention, by controlling the microwave input energy and adjusting the microwave heating power and microwave time, the temperature distribution can be effectively controlled, hollowing can be suppressed, and the desired microstructure can be obtained, with the total energy controlled at 120±5 kJ. Attached Figure Description

[0026] Figure 1 This is a flowchart of Example 1, which describes the solidification of simulated lunar soil using a mixture of urease-producing microorganisms. Figure 2 This is a macroscopic photograph of the specimen in Example 1 under microwave heating power of 1000W; Figure 3 This is a macroscopic photograph of the specimen under microwave heating power of 800W in Example 2; Figure 4 This is a macroscopic photograph of the specimen in Example 3 under microwave heating power of 600W; Figure 5 This is a macroscopic photograph of the specimen in Example 4 under microwave heating power of 300W; Figure 6 The images show a comparison of scanning electron microscope (SEM) images of simulated lunar soil solidification in Examples 1 and 5.

[0027] Figure 7 The images show a comparison of scanning electron microscope (SEM) images of lunar soil solidification under different microwave parameters in Examples 1-4. Detailed Implementation

[0028] The present invention will be further explained below with reference to the embodiments and accompanying drawings, but this is not intended to limit the scope of protection of this application.

[0029] The present invention provides a microwave-assisted method for the rapid formation of simulated lunar soil through microbial-induced precipitation and solidification, comprising the following steps: The simulated lunar soil was directly mixed with ground anhydrous calcium chloride powder to obtain a powder mixture; Urease-producing bacteria were screened from soil using a culture medium containing urea and nutrients to obtain microbial agents; The microbial agent is mixed with the powder mixture to obtain a paste. Microwave treatment of the paste enables rapid solidification of simulated lunar soil.

[0030] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0031] This invention grinds blocky basalt to obtain basalt powders with different gradations, and prepares simulated lunar soil based on the actual particle size distribution of lunar soil.

[0032] This invention does not have special requirements for the grinding process, as long as the particle size distribution of the pulverized basalt powder is between 35 and 65 mesh. ), 65~100 mesh ( ), 100~200 mesh ( ) and >200 mesh ( Four particle size ranges are sufficient. This invention strictly controls the particle size of basalt powder within the above distribution range, aiming to simulate the particle size distribution of real lunar soil.

[0033] In this invention, the massive basalt has a similar chemical composition and proportion to real lunar soil.

[0034] This invention grinds anhydrous calcium chloride particles to obtain calcium chloride powder.

[0035] This invention does not have special requirements for the grinding process of the calcium chloride, as long as the particle size of the ground powder is ≤ That's it. In an embodiment of the invention, the calcium chloride powder is ground into powder using a mortar and pestle and then passed through a 200-mesh sieve. The present invention strictly controls the particle size of the calcium chloride powder within the above-mentioned range, which is beneficial for better mixing of the calcium chloride powder with the simulated lunar soil and achieving a more uniform distribution of the calcium chloride powder.

[0036] The simulated lunar soil and anhydrous calcium chloride powder are mixed at a mass ratio of 10 to 20:1, with a preferred mass ratio of 15:1.

[0037] This invention uses a specific culture medium to screen urease-producing microbial communities in soil. The urease-containing microorganisms include various species such as Bacillus pasteurellii and Bacillus subtilis that have the ability to degrade urea and generate carbonate.

[0038] In this invention, the bacterial strain is enriched and cultured in a culture medium, and the microbial agent is obtained after 24 hours of culture.

[0039] The present invention does not have special requirements for the preparation process of the culture medium; urea and yeast extract can be directly dissolved in water.

[0040] In this invention, the concentration of urea in the culture medium is ≤1 mol / L, and the concentration of yeast extract is ≤5 g / L. This invention does not impose special requirements on the molar ratio of urea to calcium ions; however, since the molar amount of carbonate ions during the reaction is affected by the microbial inoculant, an excess of calcium ions is selected to control the mass of calcium chloride at a constant level.

[0041] After obtaining the microbial agent, the present invention mixes the powder mixture and the microbial agent to obtain a paste.

[0042] The present invention does not have special requirements for the mixing process, as long as the powder mixture and the microbial agent are mixed evenly.

[0043] In this invention, the preferred mass ratio of the powder mixture to water in the microbial inoculant is 1:(0.20~0.32). In specific embodiments of this invention, the mass ratio of the powder mixture to water in the microbial inoculant can be 1:0.20, 1:0.24, 1:0.28, or 1:0.32. Within the above range, the higher the mass ratio of the powder mixture to water in the microbial inoculant, the greater the mass of calcium carbonate produced.

[0044] In this invention, the microwave energy input is controlled similarly, with the microwave power preferably ranging from 300W to 1000W and the microwave time preferably ranging from 2 minutes to 6.5 minutes. In specific embodiments of this invention, the microwave power can be 300W, 600W, 800W, or 1000W, corresponding to microwave times of 6.5 minutes, 3.5 minutes, 2.5 minutes, or 2 minutes, respectively. This invention promotes rapid molding and hardening of the paste by controlling the microwave action parameters within the above range. Further, the microwave power is preferably 700 to 1000W.

[0045] In this invention, the process from initial sample preparation to molding and hardening takes no more than 30 minutes.

[0046] In this invention, all preparation processes are carried out at room temperature (25°C) (that is, the samples after each microwave treatment are stored at 25°C).

[0047] This invention eliminates the step of preparing calcium chloride into a solution, avoids uneven distribution of calcium carbonate, reduces water consumption from multiple reinforcement steps in cyclic injection, and shortens the material's curing time. Specifically, simulated lunar soil is directly mixed with ground anhydrous calcium chloride powder. Utilizing the property of calcium chloride dissolving in a liquid environment to form calcium and chloride ions, free calcium ions are obtained by dissolving the calcium chloride in the liquid environment using microbial agents. In the urease-producing bacterial screening medium, urea in the medium undergoes a chemical reaction through urease to create an alkaline environment, which then produces carbonate ions required by the microbial agent. The calcium ions in the microbial agent react with the carbonate ions to rapidly generate calcium carbonate precipitate (bioforming), thus avoiding the problem of uneven distribution of calcium carbonate. By directly mixing microbial inoculants, simulated lunar soil, and calcium chloride powder, and using only water molecules in the microbial inoculants as a carrier of the liquid environment, a paste is directly prepared, reducing the water consumption of multiple reinforcement steps in cyclic injection. Through microwave action, the water molecules in the paste are evaporated, enabling the paste to harden and form rapidly, shortening the material's forming and hardening time. In addition, microwave assistance also causes the unbiodegraded urea molecules in the bacterial solution to decompose upon heating, combining with calcium ions in the solution to form calcium carbonate precipitate (chemical forming). The recrystallization of calcium chloride under microwave action (physical forming) can improve the density of the simulated lunar soil. The calcium carbonate and the recrystallized calcium chloride together solidify the simulated lunar soil.

[0048] This invention integrates bio-forming, chemical forming, and physical forming to achieve rapid solidification and forming of simulated lunar soil. Bio-forming refers to the use of the MIP process, where carbonate ions combine with calcium ions to form calcium carbonate precipitate. Chemical forming involves the thermal decomposition of undegraded urea molecules in the bacterial solution, which combine with calcium ions in the solution to form calcium carbonate precipitate. Physical forming, in addition to the physical dehydration process of calcium carbonate, also includes the recrystallization of excess calcium chloride dissolved in the bacterial solution after microwave treatment.

[0049] The temperature difference at the center of the specimen before and after microwave treatment is controlled at ΔT = 110 ± 20℃ (initial temperature is room temperature). Under this microwave treatment, the material does not sinter, achieving both chemical and physical forming. ΔT represents the center temperature difference.

[0050] The following detailed description of the method for rapid solidification of microbial-induced calcium carbonate precipitation to simulate lunar soil provided by the present invention, with reference to specific embodiments, should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1 according to Figure 1 The process shown rapidly solidifies simulated lunar soil. The specific steps are as follows: (1) Preparation of calcium chloride powder: Grind calcium chloride particles into powder using a mortar and pestle and pass through a 200-mesh sieve.

[0052] (2) Preparation of simulated lunar soil: Massive basalt with similar chemical composition and proportions was ground into powder and then processed into 35-65 mesh. ), 65~100 mesh ( ), 100~200 mesh ( ) and >200 mesh ( Four particle sizes were graded in a ratio of 2:3:5:6 to obtain simulated lunar soil.

[0053] (3) Preparation of microbial inoculants: The concentration of urea was 1 mol / L and the concentration of yeast extract was 5 g / L. Culture medium solution was prepared. Urease-producing microbial communities were screened from the soil using a specific culture medium and obtained as microbial inoculants after 24 h of culture.

[0054] (4) Paste preparation: The simulated lunar soil and calcium chloride powder were stirred evenly at a mass ratio of 15:1 to obtain a powder mixture. 50g of the powder mixture was mixed with 10mL of microbial agent to obtain a paste.

[0055] (5) Molding and hardening treatment: The paste was placed in a 20mm×20mm×20mm silicone mold and microwaved at 1000W for 2 minutes. The results of the obtained specimens are shown in [the table below]. Figure 2 .

[0056] Example 2 The steps in this embodiment are the same as in Embodiment 1, except that a microwave treatment at 800W for 2.5 minutes is performed. The obtained test specimen results are shown below. Figure 3 .

[0057] Example 3 The steps in this embodiment are the same as in Embodiment 1, except that a microwave treatment of 600W for 3.5 minutes is performed. The obtained test specimen results are shown below. Figure 4 .

[0058] Example 4 The steps in this embodiment are the same as in Embodiment 1, except that a microwave treatment of 300W for 6.5 minutes is performed. The obtained test specimen results are shown below. Figure 5 .

[0059] Example 5 The steps in this comparative example are the same as in Example 1, except that microwave treatment is not performed in this comparative example. Instead, the prepared paste is directly dried at 40°C until it is completely hardened. The experiment was conducted at room temperature (25°C).

[0060] Performance testing: Experiment 1: Curing Time Test Curing time: Weigh the test block every two hours. When the mass change between two consecutive weighings is less than 0.5g, the test block is considered to be fully cured.

[0061] Test results: Examples 1, 2, 3, and 4 were fully hardened and molded after microwave treatment for 2 min, 2.5 min, 3.5 min, and 6.5 min, respectively; Example 5 was fully hardened and molded after drying at 40°C for 40 hours.

[0062] Macroscopic physical images of Examples 1, 2, 3, and 4 are shown below. Figures 2-5 As shown, comparison Figures 2-5 As can be seen, the macroscopic morphology of the samples differs under different microwave parameters. Mechanical testing revealed that under low power conditions, the microparticles were more distributed and less tightly packed, with the presence of fragmented grains preventing the formation of a dense structure, resulting in relatively poor mechanical properties. Furthermore, surface smoothness does not reflect the quality of mechanical properties.

[0063] Experiment 2: Field Emission Scanning Electron Microscopy (SEM) Experiment Field emission scanning electron microscopy was used to observe the pastes after different molding and hardening methods in Examples 1 and 5. The results are as follows: Figure 6 As shown. Figure 6 In the figure, a, c, and e represent the microstructures of calcium carbonate in the cured sample of Example 1 of this invention at 2000X, 2700X, and 3000X, respectively. Figure 6 b, d, and f represent the microstructures of calcium carbonate in the dried paste of Example 5 at 2000X, 2700X, and 3000X, respectively.

[0064] Field emission scanning electron microscopy was used to observe the pastes from Examples 1, 2, 3, and 4 after exposure to different microwave powers. The results are as follows: Figure 7 As shown. Figure 7 In the figure, a, b, c, and d correspond to the microstructure of the cured samples of Examples 1, 2, 3, and 4 at 3000X, respectively. Figure 7 a and Figure 6 In the image, e represents electron micrographs of the same sample obtained in different detection areas.

[0065] from Figure 6 Overall, the SEM images of Example 1 and Example 5 show differences, mainly in the filling effect between particles. Since the urea in the liquid phase has undergone pre-hydrolysis treatment, a rapid chemical reaction can occur between the solid and liquid phases to form calcium carbonate. Thorough mixing of the calcium chloride powder in the solid phase with the simulated lunar soil raw material plays a positive role in the uniform distribution of the calcium carbonate cementing material.Figure 6 In images a and c, simulated lunar regolith particles are encapsulated by calcium carbonate crystals, with the pores between particles filled to form calcium carbonate clusters. These clusters act as a binding and filling framework between the simulated lunar regolith particles. Meanwhile, no distinct simulated lunar regolith particles were observed; most particles had a certain degree of calcium salt adhesion on their surface and were encapsulated and agglomerated into a unified whole by lamellar material. Different crystal forms of calcium carbonate, such as aragonite, calcite, and granite, are also clearly visible. Figure 6 As seen in images b and d, although the simulated lunar soil particles are similarly encapsulated by calcium salt crystals, the difference lies in the fact that the particles are mostly connected by agglomeration of individual cementing substances, and the calcium salt substances on the outer surface are mostly small and loose. Figure 6 From e and f, we can see that the products generated by both different hardening and molding methods contain calcite, but Figure 6 In the middle f, calcite is enclosed in a rhombic shape, while Figure 6 The middle part (e) appears as a mass of randomly distributed calcite. Calcium carbonate produced by simply using a drying process only acts as an interparticle binder. Furthermore, because the generated calcium carbonate crystals cannot form more effective interparticle encapsulation, large pores cannot form more effective connections, resulting in lower strength. Additionally, the absence of calcium chloride recrystallization further reduces strength. The microwave-assisted rapid prototyping method of this invention avoids these problems.

[0066] from Figure 7 Overall, the SEM images of Examples 1, 2, 3, and 4 show differences, mainly in the crystal type and intercrystalline bonding structure of calcium carbonate. At a high power of 1000W, the cementing material exhibits an irregular morphology, composed of a shell-like structure and encapsulated calcite rhombic polyhedral crystals. Figure 7 In (a) a cemented cluster structure is formed. When the power is reduced to 800W, the morphology of the product changes to a typical aragonite columnar morphology. Figure 7 In (b), the coating thickness decreases. When the power is increased to 600W, the uncoated calcite rhombic polyhedral structure can be observed. Figure 7 (c)). At 300W, unencapsulated calcite rhombic polyhedra and independent calcite cubic crystals appeared in the product. Figure 7 (d) As the power decreases, the calcite content decreases, and under low power conditions, the calcium carbonate crystals appear as independent, unencapsulated crystals, with the connection between particles only through loose, fine crystals. The high-power microwave-assisted method discovered in this invention avoids the above problems; therefore, a microwave power of 800-1000W is preferred.

[0067] In the microbial inoculant preparation stages of Examples 1, 2, 3, and 4, urea in the culture medium was pre-hydrolyzed by microorganisms, releasing free carbonate ions. Simultaneously, extracellular substances secreted by the microorganisms during growth (such as extracellular polysaccharides and proteins) carry surface charges and can adsorb some carbonate ions through electrostatic interactions, thus achieving preliminary enrichment of nucleation precursors. During the subsequent paste preparation process, these free carbonate ions electrostatically match with calcium ions in the system, gradually tending to form precipitates. Besides the nucleation sites provided by extracellular substances, the microbial cells themselves can also serve as effective nucleation centers for the formation of cemented calcium carbonate. To improve reaction uniformity, calcium chloride powder was pre-mixed with simulated lunar soil solids to achieve a uniform distribution of the calcium source; subsequently, the microbial inoculant was added to prepare a paste-like system. This method not only significantly improved the contact efficiency between microorganisms and the solid matrix but also provided a more uniform and extensive spatial distribution for calcium carbonate deposition, thereby effectively promoting the cementation process. During the microwave curing stage, the electromagnetic waves induce violent movement and rapid evaporation of water molecules within the paste, promoting rapid dehydration of the sample and accelerating the formation and transformation of calcium salt crystals, directly contributing to its overall strength. In summary, the direct mixing of powder and microbial agents positively promotes the rapid formation and uniform distribution of calcium carbonate, while the introduction of microwave forming technology significantly shortens the material preparation cycle, demonstrating a good synergistic effect.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection content of the present invention.

[0069] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for rapid molding of simulated lunar soil by microwave-assisted microbial-induced precipitation and solidification, characterized in that, Includes the following steps: The simulated lunar soil was directly mixed with ground anhydrous calcium chloride powder to obtain a powder mixture; Urease-producing bacteria were screened from soil using a culture medium containing urea and nutrients to obtain microbial agents; The microbial agent is mixed with the powder mixture to obtain a paste. Microwave treatment of the paste enables rapid solidification of simulated lunar soil.

2. The method according to claim 1, characterized in that, The total energy of microwave treatment was controlled at 120±5kJ, and the temperature difference at the center before and after microwave treatment was controlled at ΔT=110±20℃.

3. The method according to claim 1, characterized in that, The parameters for microwave processing are: microwave power 300~1000W, 2min~6.5min.

4. The method according to claim 1, characterized in that, The parameters for microwave processing are: microwave power 700~1000W, microwave time 2min~3min.

5. The method according to claim 1, characterized in that, The particle size of the anhydrous calcium chloride powder is ≤75μm; The simulated lunar soil is prepared from basalt powder of different particle sizes, and the simulated lunar soil has a similar chemical composition to the basalt powder; the urease-producing bacteria include a variety of microorganisms that can induce the precipitation of calcium carbonate, including Bacillus pasteurellii and Bacillus subtilis; the concentration of urea in the culture medium is ≤1mol / L, and the concentration of yeast extract is ≤5g / L.

6. The method according to claim 1, characterized in that, The mass ratio of anhydrous calcium chloride powder to simulated lunar soil is 1:10~20, preferably 1:

15.

7. The method according to claim 1, characterized in that, The agent-to-solid ratio of the microbial agent to the powder mixture is 0.20~0.

32.

8. The method according to claim 1, characterized in that, The preparation of the paste was carried out at room temperature.

9. A microwave-assisted microbial-induced precipitation and solidification simulated lunar soil rapid prototyping material, characterized in that, The material is obtained by the method described in any one of claims 1-8.

10. A method for simulating lunar soil by microbial-induced precipitation and solidification, characterized in that, Includes the following steps: The simulated lunar soil was directly mixed with ground anhydrous calcium chloride powder to obtain a powder mixture; Urease-producing bacteria were screened from soil using a culture medium containing urea and nutrients to obtain microbial agents; The microbial agent is mixed with the powder mixture to obtain a paste. The paste is dried at 40-50℃ until it is completely hardened inside, thus achieving low-moisture solidification to simulate lunar soil.

Images