An extrusion-based additive manufacturing method for lunar soil in situ on the lunar surface

Abstract

This invention provides an extrusion-based additive manufacturing method for lunar regolith on the lunar surface, comprising the following steps: Step 1, preparing a lunar regolith paste system; Step 2, paste extrusion 3D printing; Step 3, prototype performance enhancement. Lunar regolith is mixed with a small amount of resin on the lunar surface in situ to form a soft material with controllable viscosity, which can be precisely controlled under microgravity. Three-dimensional extrusion molding is performed using an extrusion device, followed by curing in the lunar surface's ultraviolet and high-temperature environment. This technology enables the curing of lunar regolith particles with a small amount of resin, uses low-power equipment, and utilizes the lunar surface's ultraviolet radiation and high-temperature environment to enhance the curing effect. It achieves effective control of lunar regolith particles under microgravity, minimizes the amount of curing agent used, reduces Earth-Moon transportation costs, and enables rapid in-situ preparation of high-strength, high-precision lunar regolith structural / functional components.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of in-situ additive manufacturing in space, and particularly relates to an extrusion type lunar soil additive manufacturing method for in-situ manufacturing on the moon surface. BACKGROUND

[0002] In-situ utilization technology of space resources is the basis for realizing the goal of space exploration missions. The moon has abundant strategic resources such as helium-3, rare earth, silicon, etc., which are important supplements to the resources on the earth and important resource storage stations and transfer stations for future deep space exploration. In-situ utilization technology of lunar resources has important significance for the follow-up development of manned lunar projects. The moon surface is covered with a large amount of lunar soil, which contains a large amount of silicon and aluminum oxides, similar to silicate ceramics, and can be used as raw materials for in-situ manufacturing on the moon surface. The investigation and verification of in-situ resource utilization technology for lunar exploration provide technical accumulation and reference for future exploration of Mars and other planets in the solar system.

[0003] Contour Crafting uses sulfur as a waterless curing agent to form sulfur concrete after heating and cooling. This technology first prints the contours of components through a lunar soil extrusion device, and then pours concrete inside; but the early experiments show that the impact resistance of sulfur concrete needs to be improved, and the material needs to meet specific performance before the process is applied on the moon surface, the proportion of in-situ resources needs to be improved, the printed structure needs to meet the requirements of structural stability and precision, and a large amount of resources such as sulfur, water and oxygen need to be supplied.

[0004] ESA proposed a method called "D-shape" for building on the moon surface, which uses a 3D printing device that simulates lunar sediment soil. The device is based on a 6m wide frame, and the nozzle of the printer moves inside the frame to spray water-based curing agents onto the surface of the lunar soil and magnesium-based compound pre-mixed materials, which solidify into usable structural materials in cooperation with several materials. According to the principle of D-shape printing, building a lunar base requires building a large motion frame, making the nozzle of the 3D printer move in it, and uniformly pre-mixing lunar soil and magnesium-based compounds. There are still obvious technical bottlenecks for application on the moon surface, and the applicability on the moon surface needs to be further investigated.

[0005] In the aspect of lunar soil sintering technology research, researchers at home and abroad have proposed using electron beam, laser, solar energy and microwave to sinter lunar soil for in-situ manufacturing. The current feasibility study of lunar soil electron beam selective sintering process shows that lunar soil mineral composition contains a large amount of aluminum, titanium, iron and other elements, which can be directly used for in-situ manufacturing with single lunar soil material, but it faces the problems of large equipment power consumption, low forming structure precision, and large brittleness, and the lunar surface applicability is generally poor. ESA proposes a lunar soil forming technology based on solar sintering, which uses a concentrator array to collect sunlight for lunar soil melting sintering. This method does not consume external energy and can also produce oxygen, but it needs to build large lunar solar concentrating facilities, which has high resource line pressure, and the mechanical properties of the formed products are low. Microwave sintering technology is based on the direct interaction between microwave and material particles, which makes the sample directly absorb microwave energy to realize lunar soil heating and sintering. Researchers have conducted sintering tests on lunar soil collected by Apollo mission, which has verified that microwave can make lunar soil produce "transient liquid phase" to rapidly heat and sinter locally, but this technology has high demand for lunar energy and low forming precision, which cannot meet the manufacturing demand of complex structures on the lunar surface. SUMMARY

[0006] In view of the defects of the prior art, the present application provides an extrusion type lunar soil additive manufacturing method for lunar in-situ manufacturing, which can effectively solve the above problems.

[0007] The technical scheme adopted by the present application is as follows:

[0008] The present application provides an extrusion type lunar soil additive manufacturing method for lunar in-situ manufacturing, comprising the following steps:

[0009] Step 1, preparing a lunar soil paste system:

[0010] Take the formula amount of lunar soil, resin, resin heat curing additive, resin photocuring additive, dispersant and thickening agent, mix uniformly to obtain a lunar soil paste system;

[0011] Among them: the addition amount of each component is: 70-90 parts by weight of lunar soil; 10-15 parts by weight of resin; 0.01-1 parts by weight of resin heat curing additive; 0.05-0.8 parts by weight of resin photocuring additive; 0.05-4 parts by weight of dispersant; 0.1-5 parts by weight of thickening agent;

[0012] Step 2, paste extrusion 3D printing:

[0013] Through paste extrusion 3D printing technology, the lunar soil paste system prepared in step 1 is printed and formed to obtain a prototype;

[0014] Specifically, the lunar soil paste system flows in the extrusion head, the paste viscosity decreases with the increase of the shear rate, and when the shear rate is 10 -4 -10 3 s -1 , the paste viscosity is 10 -3 -10 5 Pa·s, and the paste can be successfully extruded; after the lunar soil paste system is extruded from the extrusion head, the shear rate decreases to zero, the paste maintains the geometric shape when it is separated from the extrusion head, and the extruded paste is accumulated on the surface of the printing platform through the extrusion filament, and heat treatment and light treatment are performed on the extruded paste to realize the thermal curing and photocuring of the resin in the paste, and the prototype is obtained.

[0015] Preferably, the median particle size of the lunar soil is 0.1-200 microns, and the maximum particle size does not exceed the inner diameter of the extrusion head.

[0016] Preferably, the resin is one or a mixture of several of acrylate resin, epoxy resin, silicone resin and polyimide resin.

[0017] Preferably, the resin thermal curing additive includes a thermal curing agent and a curing accelerator; the resin photocuring additive includes a photoinitiator and a photosensitizer.

[0018] Preferably, the dispersant is a high molecular dispersant, specifically one or a mixture of several of KOS110, SP711, BYK110, BYK190, silane coupling agent, SP710 and SP769Z dispersant.

[0019] Preferably, the thickening agent is any one of inorganic and organic thickening agents.

[0020] Preferably, the thickening agent is any one of xanthan gum, ASE-60 and DN-2024.

[0021] Preferably, in step 1, the following method is used for uniform mixing:

[0022] First, the resin, resin thermal curing additive and resin photocuring additive are fully mixed and uniformly mixed to obtain a first mixture; then the lunar soil, dispersant and thickening agent are added to the first mixture, and fully mixed and uniformly mixed to obtain the final lunar soil paste system.

[0023] Preferably, in step 2, the extruded paste is subjected to heat treatment and light treatment to realize the thermal curing and photocuring of the resin in the paste, and the prototype is obtained, specifically:

[0024] The extruded paste is heat treated by a lunar surface in-situ high-temperature environment or a specific heating device in a way of conduction heat transfer or radiation heat transfer, so as to realize the heat curing of the resin in the paste; meanwhile, an auxiliary light curing mode is adopted, that is, a certain wavelength of light is applied to the extruded paste during printing, so as to realize the light curing of the resin in the paste; wherein, the wavelength determination method of the light is as follows: according to the ultraviolet-visible absorption spectrum of the resin light curing additive, a light source with a corresponding wavelength range is selected, so that the resin light curing additive is cracked to generate free radicals, and the resin light curing is realized.

[0025] Preferably, it also includes:

[0026] Step 3, prototype performance enhancement step:

[0027] The prototype is subjected to debinding and sintering treatment, the resin in the prototype is removed through 450 DEG C debinding treatment, the resin is decomposed into small molecules and removed; after the debinding is completed, the temperature is increased to 1000-1300 DEG C, and the sintering is performed for 48h, the sintering atmosphere is inert gas environment, and the formed lunar soil structure part.

[0028] The extrusion type lunar soil additive manufacturing method for lunar surface in-situ manufacturing provided by the application has the following advantages:

[0029] The lunar soil is mixed with a small amount of resin in-situ on the lunar surface to form a soft material with controllable viscosity, which can be accurately controlled under microgravity, and is subjected to three-dimensional extrusion molding by using an extrusion device, and is cured by combining the ultraviolet on the lunar surface and the high-temperature environment. This technology can realize the curing of lunar soil particles by using a small amount of resin, the power consumption of the used equipment is low, the ultraviolet irradiation on the lunar surface and the high-temperature environment are used in-situ to strengthen the curing effect, the lunar soil particles can be effectively controlled under microgravity, the amount of curing agent can be maximized, the transportation cost between the earth and the moon can be reduced, and the in-situ rapid preparation of high-strength and high-precision lunar soil structure parts / function parts can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flowchart of the extrusion type lunar soil additive manufacturing method for lunar surface in-situ manufacturing provided by the application is shown. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects of the application clearer, the application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application, and are not used to limit the application.

[0032] The present application provides an extrusion molding technology, which mixes lunar soil with a small amount of resin in situ on the lunar surface to form a soft material with controllable viscosity, which can be precisely controlled under microgravity, and is solidified by using an extrusion device for three-dimensional extrusion molding in combination with ultraviolet and high temperature environment on the lunar surface. This technology can realize solidification of lunar soil particles by using a small amount of resin, has low power consumption of the used equipment, strengthens the solidification effect by using ultraviolet radiation and high temperature environment on the lunar surface in situ, can effectively control the lunar soil particles under microgravity, and can maximize the reduction of the amount of solidification agent, reduce the transportation cost between the earth and the moon, and realize rapid in-situ preparation of high-strength and high-precision lunar soil structural parts / function parts.

[0033] The present application provides an in-situ additive manufacturing method of lunar soil under the harsh lunar surface environment of microgravity, high vacuum, high and low temperature alternation and strong radiation, which provides technical support for future lunar exploration projects. The solidified lunar soil manufactured by the technology can be used as a structural material for the protection structure / experimental facility of lunar load and the building module of lunar exploration base.

[0034] The present application provides an extrusion type lunar soil additive manufacturing method for in-situ manufacturing on the lunar surface, referring to Figure 1 , comprising the following steps:

[0035] Step 1, preparing a lunar soil paste system:

[0036] Taking a formula amount of lunar soil, resin, resin thermal curing additive, resin photocuring additive, dispersant and thickening agent, mixing uniformly to obtain a lunar soil paste system;

[0037] In the formula, the addition amount of each component is: 70-90 parts by weight of lunar soil; 10-15 parts by weight of resin; 0.01-1 part by weight of resin thermal curing additive; 0.05-0.8 part by weight of resin photocuring additive; 0.05-4 parts by weight of dispersant; and 0.1-5 parts by weight of thickening agent.

[0038] In this step, the median particle size of the lunar soil is 0.1-200 microns, and the maximum particle size does not exceed the inner diameter of the extrusion head. The lunar soil includes various types of simulated lunar soil (CAS series, CLRS series, JSC series, MLS series and MKS series, etc.) and real lunar soil.

[0039] The resin is one or a mixture of several of acrylate resin, epoxy resin, silicone resin and polyimide resin.

[0040] The resin thermal curing additive includes a thermal curing agent and a curing accelerator; and the resin photocuring additive includes a photoinitiator and a photosensitizer. The photoinitiator is a free radical type photoinitiator and a cationic type photoinitiator.

[0041] The dispersant is a high-molecular dispersant, specifically one or a mixture of several of KOS110, SP711, BYK110, BYK190, silane coupling agent, SP710 and SP769Z dispersants.

[0042] The thickening agent is any one of inorganic and organic thickening agents. For example, the thickening agent is any one of xanthan gum, ASE-60 and DN-2024.

[0043] In this step, the components can be added in any order and mixed uniformly to obtain the paste at one time. However, as a preferred mode, the inventors have found that, through detection tests, the strength of the member prepared finally is higher and the effect is better when the following mode is adopted: the resin, the resin thermal curing additive and the resin photocuring additive are mixed uniformly to obtain a first mixture; then the lunar soil, the dispersant and the thickening agent are added to the first mixture and mixed uniformly to obtain the final lunar soil paste system. The resin, the resin thermal curing additive and the resin photocuring additive are mixed uniformly first, which can more specifically play the roles of the resin thermal curing additive and the resin photocuring additive, and the resin is cured better. Thus, the strength of the member prepared is improved.

[0044] The dispersant plays the roles of improving the stability of the dispersion system, improving the affinity between the lunar soil and the resin, preventing the solid particles from settling and agglomerating and reducing the viscosity of the dispersion system; the thickening agent is used to improve the viscosity of the system, improve the suspension stability of the lunar soil particles in the paste and adjust the rheological property of the paste; the resin thermal curing additive and the resin photocuring additive are used to adjust the thermal curing and photocuring properties of the resin.

[0045] In the specific mixing, a non-intrusive homogenization device or stirring, ball milling and the like are selected to mix the components to realize the uniform dispersion of the components in the mixed system.

[0046] The inventors have found that the viscosity of the paste decreases with the increase of the shear rate, showing a certain shear thinning property; by adjusting the types and amounts of the components, the paste can also show obvious thixotropy. By adjusting the mass fraction of the lunar soil in the paste or the amounts of the dispersant, the thickening agent and the like, the paste can not only meet the requirements of the lunar soil paste extrusion 3D printing, but also be applicable to the 3D printing technologies such as stereolithography or digital light processing technology. By adding the thermal curing agent and the curing accelerator, the thermal curing of the resin can be realized; by adding the photoinitiator and the photosensitizer, the photocuring of the resin can be realized. In the present application, the curing mode of the paste is mainly thermal curing and secondarily photocuring.

[0047] Step 2, paste extrusion 3D printing:

[0048] The lunar soil paste system prepared in step 1 is printed by a paste extrusion type 3D printing technology to obtain a prototype;

[0049] Specifically, the lunar soil paste system has obvious shear thinning characteristics or thixotropy. When the lunar soil paste system flows in the extrusion head, the viscosity of the paste decreases with the increase of the shear rate, and when the shear rate is 10 -4 -10 3 s -1 , the viscosity of the paste is 10 -3 -10 5 Pa·s, and the paste can be successfully extruded; after the lunar soil paste system is extruded from the extrusion head, the shear rate decreases to zero, the paste maintains the geometric shape when it is separated from the extrusion head, and the extruded paste is accumulated on the surface of the printing platform. Through heat treatment and light treatment of the extruded paste, thermal curing and photocuring of the resin in the paste are realized, and a prototype is obtained.

[0050] The diameter of the extrusion head can be 0.2mm-1cm.

[0051] In this step, the extruded paste is heat treated and light treated to realize thermal curing and photocuring of the resin in the paste, and a prototype is obtained, specifically:

[0052] Photocuring includes various simulated light sources and lunar light sources; thermal curing includes various ground heat sources and lunar solar radiation heat sources.

[0053] The extruded paste is heat treated by means of conduction heat transfer or radiation heat transfer, such as heat energy and microwaves, through lunar in-situ high-temperature environment or special heating equipment, to realize thermal curing of the resin in the paste; at the same time, assisted photocuring is used, that is, a certain wavelength of light is applied to the extruded paste during printing to realize photocuring of the resin in the paste; wherein the wavelength determination method of the light is as follows: according to the ultraviolet-visible absorption spectrum of the resin photocuring additive used, a light source with a corresponding wavelength range is selected to make the resin photocuring additive crack and generate free radicals, so as to realize resin photocuring. For example, when the photoinitiator 819 (phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide) is used as a free radical photoinitiator, according to its ultraviolet-visible absorption spectrum, a light source with a wavelength in the range of 200-450nm can be selected to make it crack and generate free radicals. As an embodiment, a LED light source with a wavelength of 405nm is used to make the photoinitiator 819 crack and realize resin photocuring.

[0054] By means of lunar in-situ light conditions, the resin can be cured, and the energy consumption can be reduced.

[0055] After the light / heat treatment, the resin in the prototype is completely cured, and the performance of the printed part can meet the requirements of lunar application, and the printed part can be directly used.

[0056] In addition, in order to further improve the mechanical strength of the printed part and the resistance to the lunar surface environment, the printed part can be subjected to a debinding and sintering treatment. The purpose of debinding is to remove the resin in the prototype part, and the resin can be decomposed into small molecules at high temperature. After complete decomposition, only lunar soil is left. The organic components can be completely removed at about 450°C. After debinding is completed, the temperature is raised to 1000-1300°C for sintering, and the lunar soil structure part is formed, i.e., step 3 is performed.

[0057] Step 3, performance strengthening step of the prototype part:

[0058] The prototype part is subjected to a debinding and sintering treatment. Through 450°C debinding treatment, the resin in the prototype part is removed, and the resin is decomposed into small molecules and removed. After debinding is completed, the temperature is raised to 1000-1300°C, and the sintering atmosphere is an inert gas environment, such as argon, nitrogen, etc., for 48h, and the lunar soil structure part is formed.

[0059] The present application has the following advantages:

[0060] 1. The paste can realize high solid content. In order to reduce the cost of the earth-moon uplink, the amount of resin and various additives in the paste is as small as possible. In the present application, the mass fraction of lunar soil in the paste can reach 90%, which has obvious advantages compared with the existing extrusion type 3D printing lunar soil slurry.

[0061] 2. The component has high strength. The component does not need post-treatment processes such as debinding and sintering, and the compressive strength can be higher than 10MPa, and the highest can reach 40MPa, and the strength meets the requirements of lunar surface application.

[0062] 3. The component has good resistance to high and low temperature environments, and can be used in the range of -150-180°C without failure.

[0063] 4. The resin can be completely cured by heat treatment at 50-150°C for several hours. Through the use of the environmental conditions of lunar surface radiation heat transfer in situ, the component is hardened. Even if the component needs to be heat treated by equipment, compared with the traditional debinding and sintering heat treatment process, the energy consumption is significantly reduced.

[0064] 5. The required equipment has compact structure, high printing efficiency, and the forming precision can reach micrometer level, and 3D printing of large-size components can be realized.

[0065] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should be regarded as the protection scope of the present application.

Claims

1. An extrusion-based lunar soil additive manufacturing method for in-situ manufacturing on the lunar surface, characterized in that, The method comprises the following steps: Step 1, preparation of a lunar soil paste system: Take the formula amount of lunar soil, resin, resin thermal curing additive, resin photocuring additive, dispersant and thickening agent, mix uniformly to obtain a lunar soil paste system; the resin thermal curing additive comprises a thermal curing agent and a curing accelerator; the resin photocuring additive comprises a photoinitiator and a photosensitizer; Wherein: the addition amount of each component is: 70-90 parts by weight of lunar soil; 10-15 parts by weight of resin; 0.01-1 parts by weight of resin thermal curing additive; 0.05-0.8 parts by weight of resin photocuring additive; 0.05-4 parts by weight of dispersant; 0.1-5 parts by weight of thickening agent; Wherein: the following method is used for uniform mixing: First, the resin, resin thermal curing additive and resin photocuring additive are mixed uniformly to obtain a first mixture; then the lunar soil, dispersant and thickening agent are added to the first mixture and mixed uniformly to obtain the final lunar soil paste system; First, the resin, resin thermal curing additive and resin photocuring additive are mixed uniformly, which can more specifically play the role of the resin thermal curing additive and the resin photocuring additive, and the resin is subjected to curing treatment, so that the curing effect is better, thereby improving the strength of the prepared component; The dispersant improves the stability of the dispersion system, improves the affinity between the lunar soil and the resin, prevents solid particle sedimentation and agglomeration, and reduces the viscosity of the dispersion system; the thickening agent is used to improve the viscosity of the system, improve the suspension stability of the lunar soil particles in the paste, and adjust the rheological property of the paste; the resin thermal curing additive and the resin photocuring additive are used to adjust the thermal curing and photocuring properties of the resin; Step 2, paste extrusion 3D printing: The lunar soil paste system prepared in step 1 is printed by a paste extrusion 3D printing technology to obtain a prototype; Specifically, the lunar soil paste system flows in the extrusion head, the paste viscosity decreases with the increase of the shear rate, and when the shear rate is 10 -4 -10 3 s -1 , the paste viscosity is 10 -3 -10 5 Pa·s, and the paste can be successfully extruded; after the lunar soil paste system is extruded from the extrusion head, the shear rate decreases to zero, the paste maintains the geometric shape when it is separated from the extrusion head, is accumulated on the surface of the printing platform through the extruded filaments, and is subjected to heat treatment and light treatment, so that the resin in the paste is thermally cured and photocured, and a prototype is obtained; Wherein: the extruded paste is subjected to heat treatment and light treatment to realize thermal curing and photocuring of the resin in the paste to obtain the prototype, specifically: The photocuring includes various simulated light sources and lunar light sources; the thermal curing includes various ground heat sources and lunar solar radiation heat sources; The extruded paste is subjected to heat treatment by a lunar in-situ high-temperature environment or a heating device through conduction heat transfer or radiation heat transfer to realize thermal curing of the resin in the paste; at the same time, an auxiliary photocuring method is used, that is, light is applied to the extruded paste during printing to realize photocuring of the resin in the paste; wherein, the wavelength determination method of the light is: according to the ultraviolet-visible absorption spectrum of the resin photocuring additive, a light source with a corresponding wavelength range is selected to make the resin photocuring additive crack and generate free radicals, thereby realizing resin photocuring; Step 3, performance strengthening step of the prototype: The prototype is subjected to debinding and sintering treatment, the resin in the prototype is removed by debinding treatment at 450 DEG C to make the resin decompose into small molecules; after debinding, the temperature is raised to 1000-1300 DEG C, and the sintering is performed for 48 hours in an inert gas atmosphere to form a lunar soil structure. The paste has high solid content, and the mass fraction of lunar soil in the paste is 90%, so that the cost of uplink is reduced, and the amount of resin and various additives in the paste is reduced, which has obvious advantages compared with the existing lunar soil slurry for extrusion type 3D printing; The component has high strength and does not need post-processing of degreasing and sintering, and the compressive strength is higher than 10 MPa, and the highest is 40 MPa, so that the strength meets the requirements of lunar surface application; The component has good resistance to high and low temperature environment, and is used in the range of-150-180℃ and does not fail; The resin is completely cured by heat treatment for several hours in the range of 50-150℃, and the component is hardened by using the environmental conditions of lunar surface radiation heat transfer, so that even if the component needs to be heat treated by using equipment, the energy consumption is significantly reduced compared with the traditional degreasing and sintering heat treatment process.

2. The extrusion-based lunar soil additive manufacturing method for in-situ manufacturing on the lunar surface according to claim 1, characterized in that, The median particle size of the lunar soil is 0.1-200 microns, and the maximum particle size does not exceed the inner diameter of the extrusion head.

3. The extrusion-based lunar soil additive manufacturing method for in-situ manufacturing on the lunar surface according to claim 1, characterized in that, The resin is one or a mixture of several of acrylic resin, epoxy resin, silicone resin and polyimide resin.

4. The extrusion-based lunar soil additive manufacturing method for in-situ fabrication on the Moon according to claim 1, characterized in that, The dispersant is a high molecular dispersant, and specifically is one or a mixture of several of KOS110, SP711, BYK110, BYK190, silane coupling agent, SP710 and SP769Z dispersant.

5. The extrusion-based lunar soil additive manufacturing method for in-situ fabrication on the Moon according to claim 1, characterized in that, The thickening agent is any one of inorganic thickening agent and organic thickening agent.

6. The extrusion-based lunar soil additive manufacturing method for in-situ fabrication on the Moon according to claim 1, characterized in that, The thickening agent is any one of xanthan gum, ASE-60 and DN-2024.

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