Bionic brick, sintering mold, lunar surface protection wall and in-situ construction and reinforcement method of lunar surface protection wall

Abstract

The invention belongs to the related technical field of lunar surface buildings, and discloses a bionic brick, a sintering mold, a lunar surface protection wall and an in-situ building and reinforcing method thereof.The bionic brick comprises two layers, the two layers are formed by splicing orthohexagonal single bodies, the first layer is in a symmetrical shape, the width of the symmetrical center part is smaller than that of the two side parts, and the second layer is in a symmetrical shape; the second layer is located at a position corresponding to the symmetric center part of the first layer, extends along the width direction and is wider than the symmetric center part of the first layer; wherein the width direction is perpendicular to the direction between the two side parts of the first layer. According to the invention, a radiation path is prolonged through a bionic complex geometric structure, scattering and weakening effects are enhanced, and excellent radiation shielding performance can be realized; besides, lunar soil can be directly adopted as a main raw material and obtained through an in-situ resource utilization technology, dependence on earth resources is reduced, transportation of a large number of materials is avoided, and therefore the transportation cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of lunar architecture technology, and more specifically, relates to a biomimetic brick, a sintering mold, a lunar protective wall, and a method for in-situ construction and reinforcement thereof. Background Technology

[0002] The Moon is humanity's primary target for deep space exploration. Its unique environment and resources make it an ideal location for fundamental research in space astronomy, space physics, planetary science, and materials science. Manned lunar exploration and the construction of lunar structures are crucial means and inevitable pathways for humanity to achieve lunar habitation and the development and utilization of lunar resources in the future.

[0003] To enable long-term lunar habitation, large-scale energy storage is needed to power the habitat, and the abundant helium on the lunar surface... -3 While nuclear power plants can provide a resource base, radiation from them poses a threat to human safety. Nuclear power plants commonly use heavy concrete and lead plates for radiation protection, but these traditional building materials and construction methods offer limited protection, and transporting these materials from Earth is extremely costly. Therefore, in-situ resource utilization has become an inevitable choice to reduce construction and maintenance costs. Summary of the Invention

[0004] In response to the above-mentioned defects or improvement needs of existing technologies, this invention provides a biomimetic brick, sintering mold, lunar protective wall and its in-situ construction and reinforcement method, which solves the problems of limited protective effect and extremely high material transportation costs of traditional ground protective building materials.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a biomimetic brick is provided, comprising two layers, each layer being formed by splicing together hexagonal units, wherein the first layer is symmetrical and the width of the symmetrical center is smaller than the width of the two side parts, and the second layer is located at the corresponding position of the symmetrical center of the first layer, extends along the width direction and has a width greater than the width of the symmetrical center of the first layer; wherein the width direction is perpendicular to the direction between the two side parts of the first layer.

[0006] According to the biomimetic brick provided by the present invention, the first layer has one monomer at the symmetrical center and two monomers on each side; the second layer has three monomers.

[0007] According to the biomimetic brick provided by the present invention, the biomimetic brick is prepared by vacuum sintering of lunar soil; wherein, the vacuum sintering temperature is 1070~1090℃ and the holding time is 1-3h.

[0008] According to a second aspect of the present invention, a sintering mold for preparing the above-mentioned biomimetic brick is provided, comprising two cover molds, two powder filling molds and one enclosure; one cover mold and one powder filling mold form a powder filling space corresponding to the first layer of the biomimetic brick, and the other powder filling mold and the other cover mold form a powder filling space corresponding to the second layer of the biomimetic brick, wherein the enclosure is used to be fitted onto the outside after the two cover molds and the two powder filling molds are spliced ​​together.

[0009] According to the sintering mold provided by the present invention, the sintering mold is a graphite mold; and the powder filling space is larger than the volume of the corresponding part of the biomimetic brick.

[0010] According to a third aspect of the present invention, an in-situ construction and reinforcement method for a lunar protective wall is provided, comprising: The aforementioned biomimetic bricks were manufactured in situ using lunar soil. A lunar protective wall is formed by splicing the biomimetic bricks; wherein the biomimetic bricks are spliced ​​with the same orientation and / or adjacent biomimetic bricks are spliced ​​by flipping.

[0011] The in-situ construction and reinforcement method for a lunar protective wall provided by the present invention further includes: Preparation of microbial remediation slurry; When the biomimetic bricks are spliced ​​to form a lunar protective wall, the microbial repair slurry is applied to the splicing surface for bonding; and / or, when the lunar protective wall is damaged, the microbial repair slurry is injected into the damaged area, causing the microbial repair slurry to metabolize and generate calcium carbonate crystals, thereby repairing and reinforcing the damaged area.

[0012] The method for in-situ construction and reinforcement of a lunar protective wall provided by the present invention includes the preparation of a microbial remediation slurry, specifically comprising: Strain selection and culture: Bacillus pasteurellii was cultured in urea medium based on ammonia-yeast extract and sporulation was induced under nutrient-limited conditions; Preparation of the repair slurry: Pasteurella spores are made into biological dry powder, and then the biological dry powder is mixed with urea solution and calcium chloride solution to form a paste-like adhesive, thus forming the microbial repair slurry.

[0013] According to the in-situ construction and reinforcement method for the lunar protective wall provided by the present invention, the preparation of the repair grout further includes: Magnesium oxide is added, and the mass ratio of magnesium oxide to urea is 0.3~1.5.

[0014] According to a fourth aspect of the present invention, a lunar protective wall is provided, which is constructed and obtained by the above-described in-situ construction and reinforcement method for a lunar protective wall.

[0015] Overall, compared with the prior art, the biomimetic bricks, sintering molds, lunar protective walls, and their in-situ construction and reinforcement methods conceived by this invention offer the following advantages: 1. Traditional ground-based protective materials, such as heavy concrete, rely primarily on thickness to shield radiation, resulting in high material consumption, complex construction, and unsuitability for the moon. This invention develops snowflake-shaped and butterfly-shaped biomimetic bricks. By mimicking complex geometric structures, these bricks extend the radiation path, enhancing scattering and attenuation effects, achieving excellent radiation shielding performance with lower material usage. Furthermore, existing technologies largely rely on transporting building materials from Earth, incurring high transportation costs and being limited by rocket carrying capacity. This invention can directly utilize lunar soil as the main raw material, obtaining and processing it directly on the lunar surface through in-situ resource utilization technology, significantly reducing construction and maintenance costs while minimizing dependence on Earth's resources. 2. The complex geometric structure of the snowflake-shaped and butterfly-shaped biomimetic bricks forms an interlocking mechanism through splicing, which can effectively disperse stress and improve the overall compressive and shear strength of the protective wall. Compared with traditional loosely stacked materials, this splicing design significantly improves the stability of the structure in the low gravity and micrometeorite impact environment of the moon. 3. Traditional chemical adhesives are costly and complex to use for repairing damaged lunar materials, and are difficult to adapt to the extreme lunar environment. This invention proposes to use microbial bonding slurry, which can generate calcium carbonate crystals in the lunar environment for use in splicing and bonding of lunar soil bricks and repairing cracks. This invention utilizes the gelling substances generated by microbial metabolism to give the protective wall self-healing potential, significantly reducing maintenance costs. At the same time, the process is green and environmentally friendly and adaptable to the high vacuum and low gravity environment of the moon. 4. This invention utilizes in-situ lunar resources and addresses radiation protection for lunar nuclear power plants in low-gravity environments. It designs interlocking biomimetic lunar soil bricks with excellent radiation reduction and structural performance. Combined with low-cost and easy-to-operate microbial solidification technology, it enables self-adhesion and self-repair of the protective wall, which can reduce the construction and maintenance costs of the protective wall for lunar nuclear power plants and provide a guarantee for their long-term safe operation. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of an in-situ construction and microbial reinforcement method for a lunar protective wall provided by the present invention.

[0017] Figure 2 This is a schematic diagram of the dimensions of the snowflake-shaped lunar soil brick provided by the present invention; Figure (a) is a front view of the snowflake-shaped lunar soil brick, Figure (b) is a side view of the snowflake-shaped lunar soil brick, Figure (c) is a top view of the snowflake-shaped lunar soil brick, and Figures (d) and (e) are three-dimensional views of the snowflake-shaped lunar soil brick.

[0018] Figure 3 This is a schematic diagram of a high-purity graphite mold used for vacuum sintering snowflake-shaped lunar soil bricks, provided by the present invention.

[0019] Figure 4 These are two splicing methods for the snowflake-shaped lunar soil bricks designed in this invention. In Figure (a), the splicing method is to join a lunar soil brick that has been rotated 180° with an unrotated lunar soil brick. In Figure (b), the splicing method is to directly join unrotated lunar soil bricks.

[0020] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1, 4: Lid mold; 2, 3: Powder filling mold; 5: Enclosure. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] refer to Figure 1 This invention addresses the protection problem of lunar nuclear power plants by proposing an in-situ construction and microbial reinforcement method for a protective wall. The design of the protective wall utilizes in-situ construction technology, employing vacuum sintering to form lunar soil bricks, and microbial solidification technology for reinforcement. Specifically, it includes the following parts: (1) Design a protective wall for a lunar nuclear power plant that can provide radiation isolation and protection and adapt to the low gravity environment of the lunar surface. Further, design specific snowflake-shaped lunar soil bricks.

[0023] (2) Design a split-type vacuum sintering mold, the material of which is high-purity graphite.

[0024] (3) Vacuum sintering is performed using a mold to obtain lunar soil bricks.

[0025] (4) Prepare the culture medium and strains required for solidification and carry out the culture.

[0026] (5) Use the strain obtained in (4) to prepare the repair slurry.

[0027] (6) Apply or drip the repair slurry prepared in (5) onto the lunar soil bricks obtained in step (3) for splicing, reinforcement and repair.

[0028] refer to Figure 2This embodiment provides a biomimetic brick, which includes two layers. The two layers are formed by splicing together hexagonal units. The first layer is symmetrical and the width of the center of symmetry is smaller than the width of the two sides. The second layer is located at the corresponding position of the center of symmetry of the first layer, extends along the width direction and has a width greater than the width of the center of symmetry of the first layer. The width direction is perpendicular to the direction between the two sides of the first layer.

[0029] Furthermore, the first layer has one monomer at its symmetrical center and two monomers on each side; the second layer has three monomers. The biomimetic bricks are prepared by vacuum sintering of lunar soil; that is, lunar soil is sintered under vacuum conditions into snowflake-shaped and butterfly-shaped lunar soil bricks; the lunar soil particle size is 10~100μm. The vacuum sintering temperature is 1070~1090℃, and the holding time is 1-3h.

[0030] That is, part (1) includes: Shape Design: For the purpose of protection and isolation, a snowflake-based hexagonal structure was designed to extend the radiation path. Secondly, an interlocking structure was designed for the low-gravity environment of the lunar surface. This biomimetic brick design allows each brick to form an interlocking structure with multiple bricks to effectively distribute stress and improve the overall compressive and shear strength of the protective wall. In summary, snowflake-butterfly shaped lunar soil bricks were obtained. The snowflake shape of the lunar soil bricks comes from the overall hexagonal structure, while the butterfly shape comes from the symmetrically arranged hexagonal structure of the first layer.

[0031] Size design: Specific dimensions are as follows Figure 2 In the diagram, a, b, and c are the key design parameters. a represents the overall dimension of a single brick, i.e., the maximum width, which is also the width of the second layer; b represents the side length of a single regular hexagon; and c represents the layer height. This brick can be considered as having two layers with equal height. Clearly, the overall dimension a of a single brick is 3 times the side length b of the regular hexagon. In some specific embodiments, the overall size of the snowflake-shaped biomimetic brick is 100mm, the side length of the regular hexagon is 19.2mm, and the layer height is 20mm.

[0032] Part (2) includes: refer to Figure 3 The sintering mold is designed in a split manner, and the mold design includes five parts, including two cover molds, two powder filling molds and one enclosure. One cover mold 1 and one powder filling mold 2 form the powder filling space corresponding to the first layer of the biomimetic brick, and another powder filling mold 3 and another cover mold 4 form the powder filling space corresponding to the second layer of the biomimetic brick. The enclosure 5 is used to be fitted on the outside after the two cover molds and two powder filling molds are spliced ​​together. Figure 3 The middle cover mold 1 and the cover mold 4 are used to compact the sample in the corresponding powder filling mold. The splicing sequence is shown in the figure. The overall enclosure 5 is used to prevent sample powder from overflowing.

[0033] Furthermore, the sintering mold is a graphite mold, and the powder-filling space is larger than the volume of the corresponding part of the biomimetic brick. The lid mold has protrusions that match the corresponding powder-filling spaces; during the powder-filling assembly of the molds, the protrusions on the lid mold and the corresponding powder-filling spaces can be interlocked to achieve a limiting and fixing effect between the lid mold and the powder-filling mold. Protrusion slot structures can also be provided at the corners of the two powder-filling molds to achieve a certain limiting and fixing effect through interlocking, facilitating the smooth progress of vacuum sintering.

[0034] Specifically, due to the irregular shape of the lunar soil bricks, the powder filling mold is designed in two parts: powder filling mold 2 and powder filling mold 3, to facilitate demolding. The powder filling material used during sintering is lunar soil powder, which shrinks during molding, approximately 87%. Therefore, the inner dimensions of the mold can be enlarged based on the overall dimensions 'a' of the single lunar soil brick and the layer height 'c'. For example, the inner dimensions of the mold can be enlarged to 115mm to compensate for the shrinkage during sintering. Figure 3 The middle cover mold 1 and the cover mold 4 are the covers for the powder filling molds 2 and 3, respectively, used to compact the lunar soil and control the layer height. The additional cover molds 1 and 4 prevent the sample from leaking out after powder filling. Their envelope dimensions correspond to the molds. The overall enclosure 5 is used to surround the assembled cover mold and powder filling mold parts, and its thickness is the total thickness of the assembled sintering mold.

[0035] Mold material selection: The following conditions should be met: the mold material should not react with lunar regolith at high temperatures to avoid contaminating the bricks or damaging the mold; in the lunar environment, the materials should not undergo "cold welding" to prevent the bricks from fusing with the mold; the mold should be able to withstand a sintering temperature of 1000℃-1200℃, and its coefficient of thermal expansion should match that of the lunar regolith bricks to avoid cracking. The final material selection was high-purity graphite molds with a carbon content >99.99%. This mold has good high-temperature strength, excellent thermal shock stability, and is easy to machine. Graphite itself is a solid lubricant that facilitates demolding.

[0036] Part (3) Vacuum sintering includes: filling lunar soil into a high-purity graphite mold; applying 4000N pressure and holding for 120s to compact it; heating to 1070~1090℃ in a vacuum environment and holding for 1-3h; and obtaining the shaped brick body after natural cooling in the furnace. Specifically: Powder filling: The high-purity graphite mold designed in this invention does not require a demolding lubricant and can directly fill the sample. In specific operation, the powder filling mold 3 and the cover mold 4 can be spliced ​​together first, and then the lunar soil can be filled into the powder filling space. Then, the powder filling mold 2 can be spliced ​​onto the powder filling mold 3, and then the powder can be filled into the powder filling space to a suitable height. Finally, the cover mold 1 can be covered.

[0037] Compaction: The sintering mold filled with powder and assembled is compacted, and then the enclosure 5 is assembled.

[0038] Loading the furnace: Carefully place the assembled molds into the furnace chamber of the sintering furnace, leaving sufficient gaps between the molds. Close and lock the furnace door to ensure the vacuum seal of the furnace body.

[0039] Set the sintering process: In the sintering furnace control panel, set the heating rate to 1070~1090℃ at a rate of 10℃ / min, for example, 1070℃, and hold for 2 hours.

[0040] Cooling and demolding: After the heating process is complete, stop heating, turn off the power, and allow the mold to cool naturally in a vacuum environment with the furnace. The vacuum can only be broken when the furnace temperature has cooled below a safe level. Open the furnace door and remove the sintered lunar soil bricks.

[0041] Furthermore, biomimetic brick sintering experiments can be conducted on the ground to verify feasibility. Lunar soil or simulated lunar soil can be used as raw material in the sintering experiments. During the furnace loading stage after powder filling and compaction, a vacuum operation can be performed, i.e., starting a vacuum pump to evacuate the furnace cavity from atmospheric pressure to a low vacuum range, typically 10 Pa ~ 10 Pa. -1 Pa was used to simulate a vacuum environment. Ground experiments verified the feasibility of vacuum sintering for the preparation of this biomimetic brick.

[0042] Furthermore, a method for in-situ construction and reinforcement of a lunar protective wall is also provided. This method includes: in-situ manufacturing of biomimetic bricks as described above using lunar regolith; forming a lunar protective wall by splicing the biomimetic bricks; wherein the biomimetic bricks are spliced ​​with the same orientation and / or adjacent biomimetic bricks are spliced ​​by flipping, such as... Figure 4 As shown in the figure. In this embodiment, the lunar soil bricks adopt an interlocking structure, and the lunar soil bricks are spliced ​​together in two interlocking methods to form a protective wall; the two splicing methods are flip splicing and direct splicing. Flip splicing means that adjacent bionic bricks are flipped 180° before splicing, as shown in the figure. Figure 4 As shown in (a), direct splicing, i.e., splicing without flipping, achieves interlocking between bricks and layers. Figure 4 As shown in (b).

[0043] The in-situ construction and reinforcement method for the lunar protective wall further includes: preparing a microbial repair slurry; applying the microbial repair slurry to the splicing surface for bonding when the biomimetic bricks are spliced ​​to form the lunar protective wall; and / or, when the lunar protective wall is damaged, injecting the microbial repair slurry into the damaged area, so that the microbial repair slurry metabolizes to generate calcium carbonate crystals, thereby achieving repair and reinforcement of the damaged area.

[0044] Furthermore, the preparation of the microbial remediation slurry specifically includes: Strain selection and culture: Bacillus pasteurellii was selected as the strain for preparing the remediation slurry. It was cultured on urea medium (ATCC 1376 Medium) based on ammonia-yeast extract, and sporulation was induced under nutrient-limited conditions. The growth of Bacillus pasteurellii was tracked by measuring the absorbance of the culture medium at 600 nm. The spore concentration was adjusted to 10... 6 ~10 9 CFU / mL;

[0045] Preparation of the repair slurry: Pasteurella multocida spores are made into biological dry powder, which is then mixed with urea solution and calcium chloride solution to form a paste-like binder, thus forming the microbial repair slurry. The preparation of the repair slurry also includes adding magnesium oxide, with the mass ratio of magnesium oxide to urea being 0.3~1.5.

[0046] Specifically, part (4) of the cultured strains includes: Prepare the base buffer for the culture medium: Dissolve 15.75 g of Tris base in 1 L of deionized water to make a 0.13 M Tris buffer. Then adjust the pH to around 9.0 by adding about 2.8 mL of 50% HCl to support the growth of Bacillus pasteurellii, which exhibits the best urease activity under pH 8.5-9.5 conditions.

[0047] Add nutrients and sterilize: Divide the above 1 liter buffer solution into multiple equal portions, for example, two 400 ml portions and two 100 ml portions. Dissolve 8 g of ammonium sulfate in one 400 ml portion, 16 g of yeast extract in another 400 ml portion, add 2 g of ammonium sulfate to each of the 100 ml portions, and add 4 g of yeast extract and optionally 4-20 g of agar to the third. Urea (usually 20 g / L) should be prepared separately and sterilized by filtration through a 0.22 μm filter membrane. Other components are autoclaved at 121°C for 15-20 minutes after wrapping the containers in aluminum foil. After sterilization, add the sterile urea solution to the matrix to form a complete ATCC 1376 medium with a yeast extract concentration of 20 g / L, ammonium sulfate concentration of 10 g / L, and urea concentration of 20 g / L.

[0048] Reviving the bacterial strain: Thaw cryovials or lyophilized tubes of *Bacillus pasteurellii* at room temperature. In a sterile environment, use the tip of a micropipette to pick up a small amount of bacterial suspension or powder and streak it onto a solid ATCC 1376 agar plate. Incubate the plate at 30-31°C for 24-72 hours until a single colony appears; if no colony appears, the incubation period can be extended to 96 hours. Successful revival is typically considered when the colony diameter is 1-3 mm.

[0049] Inoculation and liquid culture: In a biosafety cabinet, pick a single colony from the plate, gently scrape it with the tip of a pipette, and transfer it to 125-500 mL of sterile liquid ATCC 1376 medium. The initial inoculation volume should be controlled at an OD600 of approximately 0.05-0.1. Place the culture flask in a shaker incubator and incubate at 30°C with shaking at 150-200 rpm for 18-48 hours. For the two-step inoculation method, pre-incubate in a small volume (e.g., 50 mL) for 12-18 hours, and then transfer 1-5% of the volume to the main medium.

[0050] Monitoring growth and harvesting the strain: Regularly measure the absorbance of the culture medium at 600 nm wavelength (OD600) using a spectrophotometer. Typically, when the OD600 reaches 0.5-2.0 (corresponding to a cell concentration of approximately 10⁻⁶), the culture is ready for harvest. 7 -10 9 (CFU / mL) is considered the end of the logarithmic growth phase or the stationary phase, at which point the peak urease activity occurs, with a culture time range of 18-24 hours. At harvest, the culture medium is centrifuged at 5000-6250 rcf for 5-10 minutes at 4°C, the supernatant is discarded, and the cells are washed 2-3 times with phosphate-buffered saline (PBS, pH 7.4, 10 mM phosphate) to remove residual media. For spore preparation, sporulation can be further induced under nutrient-restricted conditions, with the spore concentration controlled at 10... 6 -10 8 Spores / mL, for long-term storage or slurry preparation in MICP applications.

[0051] Part (5) of the preparation of the repair grout includes: Harvesting and preparing *Bacillus pasteurellii* spores: Centrifuge the previously cultured *Bacillus pasteurellii* broth at 5000-8000 rf for 5-15 minutes at 4°C, discard the supernatant, and wash the cell pellet 2-3 times with phosphate-buffered saline (PBS, pH 7.0-7.5, 10-50 mM) or physiological saline (0.85-0.9% NaCl). For sporulation induction, further culture under nutrient-restricted conditions (such as a low-nitrogen medium) for 24-72 hours can promote sporulation. Then, kill the vegetative cells by heating (80-100°C, 10-20 minutes), retaining the heat-resistant spores. Finally, adjust the spore concentration to 10. 6 -10 9 CFU / mL, as the biological component for subsequent preparation of the remediation slurry.

[0052] Preparation of biological dry powder: Harvested *Pasteurella multocida* spores can be freeze-dried or spray-dried under vacuum to form stable biological dry powder. Drying can be performed using vacuum freeze-drying or vacuum spray drying, for example, at a temperature of -40 to -80°C and a pressure of <100 Pa, or by natural air drying to remove moisture. Alternatively, a preservative can be added to the harvested *Pasteurella multocida* spores, followed by vacuum drying to form stable biological dry powder; the addition of the preservative helps to better maintain the activity of microorganisms under vacuum powdering conditions. An optional preservative for freeze-drying of *Pasteurella multocida* is as follows: composed of skim milk powder, glycerol, sucrose, and monosodium glutamate, with the following mass percentage composition: skim milk powder 13%–16%, glycerol 1%–4%, sucrose 12%–15%, monosodium glutamate 0.5%–3.5%, and the balance being sterile water.

[0053] Preparation of nutrient solution: Mix a 0.3-1.0 M urea solution and a 0.1-0.5 M calcium chloride solution at a volume ratio of 1:1 to 1:5 to form the nutrient solution. The solution should be prepared using deionized water or distilled water and filtered under aseptic conditions (using a 0.22-0.45 μm filter membrane) to remove impurities, ensuring the pH value is within the range of 6.5-8.0. Optionally, the urea solution concentration can be 0.5 M, the calcium chloride solution concentration can be 0.25 M, and the ratio of urea solution to calcium chloride solution can be 1:3.

[0054] Adding magnesium oxide: Add magnesium oxide powder simultaneously or after preparing the nutrient solution. The mass ratio of magnesium oxide powder to urea should be 0.3-1.5. Disperse the magnesium oxide evenly in the nutrient solution by stirring or ultrasonic dispersion at a power of 50-200 W for 5-10 minutes. The mass ratio of magnesium oxide powder to urea can be selected as 0.5-1.

[0055] Preparation of the repair slurry: Mix the biological dry powder with the pre-prepared nutrient solution at a mass-to-volume ratio of 1:2 to 1:5, using mechanical stirring at 100-300 rpm for 10-30 minutes or manual grinding until a uniform paste-like adhesive is formed. The viscosity of the slurry can be controlled within the range of 500-2000 cP by adjusting the water content to ensure easy application or injection into cracks. Use immediately after preparation or store for a short period at 4-10°C to maintain spore viability and avoid premature precipitation reactions.

[0056] Part (6) of the repair grout usage includes: Treating the surface of lunar regolith brick joints or repairing cracked areas: For joints, interlock the snowflake-shaped lunar regolith bricks (e.g., by flipping them 180° or directly). Gently blow the contact surfaces of the bricks with mechanical tools or compressed air to remove lunar dust, loose particles, and other contaminants, ensuring a clean surface with appropriate roughness. For crack repair, mark the damaged area and thoroughly remove internal debris using a soft brush or high-pressure air to avoid secondary contamination and ensure good interface wettability.

[0057] Applying or injecting repair grout: For joints, evenly apply repair grout to the contact surfaces of the bricks, with a thickness controlled at 0.5-2 mm. Use a scraper or spray gun to apply, ensuring coverage of over 95%, and immediately press the bricks together to promote grout penetration. For damage repair such as cracks, inject grout in small amounts multiple times using a syringe, 0.5-5 mL each time, adjusting according to the volume of the damage. The total injection volume should be 1.5-3 times the volume of the damage. Repeat 2-5 times to achieve uniform filling and deep bonding, while monitoring the grout flow to avoid overflow or air bubble formation. This process should be carried out under vacuum or low pressure.

[0058] The biomimetic bricks that need repair are tested, and mechanical cleaning and compressed gas purging are used to thoroughly remove all loose particles, moon dust fragments and other contaminants from the inside of the damaged parts and the surface of the bricks. Then, microbial repair slurry is injected precisely in small amounts multiple times using a syringe.

[0059] Microbial metabolic process: After injection, the Pasteurella spores in the slurry begin to germinate and metabolize under the vacuum and temperature fluctuations of the moon, typically activating within 1-4 hours. The spores secrete urease, which catalyzes the hydrolysis of urea into ammonia and carbon dioxide. Carbon dioxide reacts with water to produce bicarbonate ions, which further dissociate into carbonate ions in an alkaline environment, as shown in the following formula: CO(NH2)2+H2O CO2 + 2NH3 (catalyzed by bacterial urease) CO2 + H2O → H2CO3 Simultaneously, magnesium oxide slowly hydrolyzes, releasing magnesium ions and hydroxide ions, further increasing the pH and providing additional alkalinity buffering, as shown in the following formula: MgO + H₂O → Mg 2+ +2(OH) - Precipitation reaction and mineral formation: After the accumulation of metabolic products, calcium ions and carbonate ions rapidly combine to form calcite or aragonite-type calcium carbonate crystals. These crystals precipitate in situ at the contact points and pores of lunar soil particles, forming bridging structures. The formation of calcite follows this formula: Ca 2+ +CO3 2+ →CaCO3↓ Simultaneously, magnesium ions combine with ammonium ions and other anions to form insoluble minerals such as struvite or magnesium hydroxide. These auxiliary minerals enhance the hardness and stability of the calcium carbonate network. The overall mineralization process is driven by the slow evaporation of residual moisture under vacuum, reducing bubble interference. The specific magnesium oxide-involved mineralization processes include the following chemical reactions: Mg(OH)2+CO2+2H2O→MgCO3·3H2O 5Mg(OH)2+4CO2+H2O→Mg5(CO3)4(OH)2·5H2O 5Mg(OH)2+4CO2→Mg5(CO3)4(OH)2·4H2O 2Mg(OH)2+CO2+3H2O→Mg2(CO3)(OH)2·3H2O Under the vacuum and temperature conditions of the moon, microorganisms adsorbed on lunar soil particles begin to metabolize, while magnesium oxide slowly hydrolyzes. Subsequently, two key precipitation reactions occur in the system to generate calcite or aragonite-type calcium carbonate crystals and insoluble minerals such as struvite or magnesium hydroxide. These newly formed minerals precipitate in situ at the contact points of the lunar soil particles, firmly cementing them together and ultimately forming a continuous, dense, and high-strength monolithic mineralization network.

[0060] Curing: After the reaction has proceeded for several hours to several days, the unreacted water has evaporated, forming a dense mineralized network. Low loads are applied to the spliced ​​walls or repaired cracks to promote crystal growth and interweaving.

[0061] Furthermore, a lunar surface protective wall is also provided, constructed using the aforementioned in-situ construction and reinforcement method. Specifically, it is formed by splicing together the aforementioned biomimetic bricks using an interlocking structure. The specific splicing scheme for this interlocking structure is as follows... Figure 4 In Figure (a), the method of splicing lunar soil bricks after being flipped 180° with unflipped lunar soil bricks is shown. This splicing method can achieve interlocking between bricks in the same layer. After splicing, no cutting is required to achieve flatness of the upper and lower surfaces. Figure (b) shows the method of splicing all lunar soil bricks directly without flipping. This method achieves interlocking between bricks and between layers, and has a stronger ability to disperse stress and bear load. However, to achieve flatness of the upper and lower surfaces, the protruding parts of the lunar soil bricks on the upper and lower surfaces need to be cut.

[0062] Optionally, the top and bottom layers along the height direction can be spliced ​​in a way that flips with the adjacent layers, while the other layers between the top and bottom layers can be spliced ​​in the same direction without flipping, to form a lunar protective wall. This ensures both the interlocking of the intermediate layers to improve robustness and the flatness of the top and bottom surfaces, thus avoiding unnecessary workload.

[0063] Specific implementation examples of this invention: The simulated lunar soil used in this embodiment of the invention was prepared through experimental simulation. Its main components include 48.52 wt% silicon dioxide, 14.24 wt% aluminum oxide, 11.5 wt% iron oxide, 9.74 wt% magnesium oxide, 8.29 wt% calcium oxide, 2.00 wt% titanium dioxide, 0.53 wt% phosphorus pentoxide, 3.19 wt% sodium oxide, and 2.02 wt% potassium oxide. Ores (such as plagioclase, pyroxene, ilmenite, olivine, and small amounts of quartz, magnetite, and apatite) were selected according to the target composition, and then sieved and mixed to obtain the simulated lunar soil, with a median particle size of approximately 70 μm.

[0064] In this specific implementation case, the lunar soil bricks are manufactured as follows: Specific dimensions of lunar soil bricks: In this example, a=100mm, b=19.2mm, c=20mm.

[0065] Sintering mold dimensions: The filler material used during sintering is simulated lunar soil, which shrinks during molding, approximately 87%. Therefore, the inner dimensions of the mold are enlarged based on the overall dimensions 'a' of the designed lunar soil brick and the layer height 'c'. In this example, the inner dimensions of the filler mold are 115mm, and the layer height is 25mm. The cover mold has the same envelope dimensions as the filler mold, with a thickness of 5mm (compacted portion) + 25mm. The overall enclosure thickness 5 is 110mm, representing the total thickness of the sintering mold after assembly.

[0066] Vacuum sintering: Powder filling: The high-purity graphite mold is designed without the need for a release lubricant, and the sample can be directly filled. In specific operation, the powder filling mold 3 and the cover mold 4 can be spliced ​​together first, and about 224g of simulated lunar soil can be filled into the powder filling mold 3. Then, the powder filling mold 2 can be spliced ​​onto the powder filling mold 3, and about 373.4g of powder can be filled into the powder filling mold 2. Finally, the cover mold 1 can be covered. Compaction: Compact the mold filled with powder and assembled by applying 4000N pressure for 120s to make the simulated lunar soil inside the mold dense and uniform. After compaction, assemble the mold enclosure 5. Loading and Vacuuming: Carefully place the assembled molds into the furnace chamber of the sintering furnace, leaving sufficient gaps between the molds. Close and lock the furnace door to ensure a vacuum seal. Start the vacuum pump to evacuate the furnace chamber from atmospheric pressure to a low vacuum range, specifically 10 Pa. This stage primarily removes most of the air and moisture from the furnace. Setting the sintering process: In the sintering furnace control panel, set the low temperature stage to 550℃ and the high temperature holding stage to 1070℃, holding the high temperature for 2 hours; Cooling and demolding: After the heating process is complete, stop heating, turn off the power, and allow the mold to cool naturally in a vacuum environment with the furnace. The vacuum can only be broken when the furnace temperature has cooled below a safe level. Open the furnace door and remove the sintered lunar soil bricks.

[0067] Repair grout preparation: The specific operation process in this example is described in sections (4) and (5) above. In particular, the parameters such as solution, reagent, time, and size selected in this example are all median values ​​within the provided range. For example, crucially, the repair slurry is prepared by mixing Bacillus pasteurellii spores and lunar soil powder in a 1:5 ratio to form a biological dry powder, and then mixing the biological dry powder with 0.5M urea and 0.25M calcium chloride nutrient solution in a 1:3 ratio to form a paste-like adhesive.

[0068] splicing, reinforcement and repair: For the specific operation process in this example, please refer to section (6) above. In particular, the time, size and other parameters selected in this example are all the median values ​​within the provided range.

[0069] This method provides an in-situ construction and microbial reinforcement method for the protective wall of a lunar nuclear power plant. The main raw materials include lunar soil and Bacillus pasteurellium culture medium. Utilizing in-situ lunar resources, in-situ utilization is achieved through vacuum sintering, significantly reducing transportation costs. Snowflake-shaped butterfly bricks were developed, extending the radiation path through complex geometry, enhancing radiation scattering and attenuation effects. This biomimetic design approach produces lunar soil bricks with excellent radiation reduction and structural performance. Addressing the challenge of repairing lunar material damage, low-cost microbial technology with self-healing potential is used for wall bonding and repair, helping to reduce the construction and maintenance costs of the lunar nuclear power plant's protective wall and providing a reliable guarantee for its long-term safe operation. In summary, this invention proposes a lunar nuclear power plant protective isolation wall material and preparation method that combines high strength, excellent radiation shielding performance, and bio-repair capabilities, enabling in-situ resource utilization and reducing maintenance costs.

[0070] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A biomimetic brick, characterized in that, It consists of two layers, each formed by splicing together a single hexagonal unit. The first layer is symmetrical, with the width of the center of symmetry being smaller than the width of the two sides. The second layer is located at the corresponding center of symmetry of the first layer, extends along the width direction, and has a width greater than the width of the center of symmetry of the first layer. The width direction is perpendicular to the direction between the two sides of the first layer.

2. The biomimetic brick as described in claim 1, characterized in that, The first layer has one monomer at its symmetrical center and two monomers on each side; the second layer has three monomers.

3. The biomimetic brick as described in claim 1, characterized in that, The biomimetic bricks are prepared by vacuum sintering of lunar soil; wherein the vacuum sintering temperature is 1070~1090℃ and the holding time is 1-3h.

4. A sintering mold for preparing the biomimetic brick according to any one of claims 1-3, characterized in that, It includes two lid molds, two powder filling molds, and one enclosure; one lid mold and one powder filling mold form the powder filling space corresponding to the first layer of the biomimetic brick, and the other powder filling mold and another lid mold form the powder filling space corresponding to the second layer of the biomimetic brick. The enclosure is used to be fitted on the outside after the two lid molds and two powder filling molds are spliced ​​together.

5. The sintering mold as described in claim 4, characterized in that, The sintering mold is a graphite mold; and the powder filling space is larger than the volume of the corresponding part of the biomimetic brick.

6. A method for in-situ construction and reinforcement of a lunar protective wall, characterized in that, include: The biomimetic bricks described in any one of claims 1-3 were manufactured in situ using lunar soil. A lunar surface protective wall is formed by splicing together the aforementioned biomimetic bricks; The biomimetic bricks are spliced ​​together with the same orientation and / or adjacent biomimetic bricks are spliced ​​together by flipping them over.

7. The in-situ construction and reinforcement method for a lunar protective wall as described in claim 6, characterized in that, Also includes: Preparation of microbial remediation slurry; When the biomimetic bricks are assembled to form a lunar protective wall, the microbial repair slurry is applied to the splicing surface for bonding; And / or, when the lunar protective barrier is damaged, the microbial repair slurry is injected into the damaged area, causing the microbial repair slurry to metabolize and generate calcium carbonate crystals, thereby repairing and reinforcing the damaged area.

8. The in-situ construction and reinforcement method for a lunar protective wall as described in claim 7, characterized in that, The preparation of microbial remediation slurry specifically includes: Strain selection and culture: Bacillus pasteurellii was cultured in urea medium based on ammonia-yeast extract and sporulation was induced under nutrient-limited conditions; Preparation of the repair slurry: Pasteurella spores are made into biological dry powder, and then the biological dry powder is mixed with urea solution and calcium chloride solution to form a paste-like adhesive, thus forming the microbial repair slurry.

9. The in-situ construction and reinforcement method for a lunar protective wall as described in claim 8, characterized in that, The preparation of the repair grout also includes: Magnesium oxide is added, and the mass ratio of magnesium oxide to urea is 0.3~1.

5.

10. A lunar protective wall, characterized in that, The lunar protective wall is constructed and reinforced using the in-situ construction and reinforcement method described in any one of claims 6-9.

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