A multi-physical field preparation method for simulating cemented aggregate rock in lunar soil

Abstract

The application discloses a kind of multi-physical field preparation methods of simulating agglomerated rock in lunar soil, comprising the following steps: selecting raw materials similar to the chemical composition and mineral composition of real lunar soil;After the raw materials are pressed into shape, they are placed in a spark plasma sintering furnace for high-temperature sintering, and agglomerated rock is obtained after rapid cooling;The process of high-temperature sintering is carried out in a protective atmosphere.The preparation method of the application is simple, efficient and can be produced on a large scale.The preparation process reproduces the geological processes experienced during the evolution of the moon to some extent.The agglomerated rock prepared by the application has similar chemical composition and nano-microstructure to the agglomerated rock in real lunar soil, and has good consistency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of simulated lunar soil preparation, and in particular to a multi-physical field preparation method of agglutinate in simulated lunar soil. BACKGROUND

[0002] The cost of transporting between the earth and the moon is high, and it is an inevitable choice to use lunar soil resources to prepare key structural materials and carry out in-situ construction on the moon for the construction of a permanent lunar scientific research station. However, due to the scarcity of lunar soil resources, the types and quantities of lunar soil obtained at home and abroad are limited, and it is a common practice at home and abroad to use terrestrial minerals to develop simulated lunar soil similar to lunar soil. The research and development of high-fidelity simulated lunar soil is a key foundation for supporting lunar in-situ construction material research.

[0003] There is a key component, agglutinate, in lunar soil. Agglutinate is formed by the fusion of part of the minerals in the lunar soil after being hit by a meteorite at high speed, and then the unfused minerals are bonded. Agglutinate is abundant in lunar soil, and the proportion of agglutinate is about 40%-60% by volume. Therefore, the preparation of the key component agglutinate in lunar soil is a core technology for realizing high-fidelity simulated lunar soil.

[0004] So far, most of the preparation of simulated lunar soil at home and abroad is in the physical properties and chemical composition of simulated lunar soil, and the simulated lunar soil prepared lacks the key component agglutinate. Moreover, the preparation method of agglutinate is not perfect and needs further research and innovation. SUMMARY

[0005] The purpose of the present application is to overcome the above technical deficiencies, and to provide a multi-physical field preparation method of agglutinate in simulated lunar soil, which solves the technical problems of the lack of key component agglutinate in simulated lunar soil in the prior art and the imperfect preparation method of agglutinate.

[0006] A multi-physical field preparation method of agglutinate in simulated lunar soil, comprising the following steps:

[0007] Selecting raw materials similar in chemical composition and mineral composition to real lunar soil;

[0008] After the raw materials are pressed and formed, they are placed in a discharge plasma sintering furnace for high-temperature sintering, and then cooled to obtain agglutinate. The high-temperature sintering process is carried out in a protective atmosphere.

[0009] Compared with the prior art, the present application has the following advantages:

[0010] The preparation method is simple, efficient, and can be scaled up, and the preparation process reproduces the geological action in the lunar evolution process to a certain extent; the prepared cemented agglomerate rock has similar chemical composition and nano-microstructure to the cemented agglomerate rock in the real lunar soil, and has good consistency. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a thin section optical micrograph of the cemented agglomerate rock in the lunar soil from Apollo 17 sample;

[0012] Figure 2 is an SEM image of the cemented agglomerate rock prepared in Example 1 of the present application;

[0013] Figure 3 is an electron microscope image of the cemented agglomerate rock prepared in Example 1 of the present application;

[0014] Figure 4 is an X-ray diffraction image of the cemented agglomerate rock prepared in Example 2 of the present application;

[0015] Figure 5 is an SEM image of the cemented agglomerate rock prepared in Example 2 of the present application;

[0016] Figure 6 is an electron microscope image of the cemented agglomerate rock prepared in Example 2 of the present application;

[0017] Figure 7 is an SEM image of the cemented agglomerate rock prepared in Comparative Example 1 of the present application;

[0018] Figure 8 is an SEM image of the cemented agglomerate rock prepared in Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be 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 present application and do not limit the present application.

[0020] The present application provides a multi-physical field preparation method for simulating cemented agglomerate rock in lunar soil, comprising the following steps:

[0021] S1, selecting raw materials similar in chemical composition and mineral composition to real lunar soil;

[0022] S2, after the raw materials are pressed and formed, they are placed in a discharge plasma sintering furnace for high-temperature sintering, and after rapid cooling, cemented agglomerate rock is obtained.

[0023] The environment of the moon is vacuum environment, and high temperature generated by meteorite high-speed impact on the moon soil can instantaneously melt or evaporate the rocks near the impact point, part of the minerals melt to form glass phase and bond the un-melted minerals, and after rapid cooling, the bonded agglomerated rock is formed. The vesicles are formed due to the capture of solar wind energy during the high-speed impact melting process. The discharge plasma sintering furnace can pressurize during the sintering process, and is directly powered by on-off direct current pulse current for sintering, which generates discharge plasma, discharge pressure, joule heat and electric field diffusion for sintering, and has the advantages of fast heating rate, short sintering time and controllable microstructure. At the same time, the discharge plasma furnace can maintain vacuum condition and pass through inert gas. These are important conditions for the formation of nanometer and microstructure vesicles in the bonded agglomerated rock.

[0024] The present application can simulate the geological action of the moon soil after high temperature melting under the impact of meteorite to some extent by high temperature sintering in the discharge plasma sintering furnace, melting of the raw materials under high temperature and generation of a certain amount of glass phase; the vacuum environment of the moon and the formation process of the vesicles in the bonded agglomerated rock can be simulated by applying uniaxial pressure and protective atmosphere. The bonded agglomerated rock prepared by the present application is more close to the bonded agglomerated rock in the real moon soil in terms of composition and nanometer and microstructure, and has important significance for further preparation of high-fidelity simulated moon soil.

[0025] In the embodiment, the main rock type of the raw material includes at least one of basalt, plagioclase and gabbro; and the main mineral components include feldspar, pyroxene, olivine, ilmenite and magnetite.

[0026] In the embodiment, the particle size of the raw material is ≤0.25mm.

[0027] In the embodiment, the process of press forming includes: using the cylindrical graphite mold lined with graphite paper to press the raw material into a cylinder. The present application does not limit the specific conditions of press forming, and the person skilled in the art can select according to the actual situation, as long as the raw material can be compacted in the mold.

[0028] In the embodiment, the process of high temperature sintering is carried out under protective atmosphere.

[0029] Preferably, the protective atmosphere is at least one of nitrogen, helium and argon.

[0030] Preferably, the protective atmosphere is introduced by: after the discharge plasma sintering furnace is evacuated to discharge air, the protective atmosphere is introduced.

[0031] More preferably, the vacuum degree is ≤20Pa.

[0032] In the present embodiment, the uniaxial pressure applied during high-temperature sintering is 5-40 MPa, including but not limited to 5 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, etc.; the maximum sintering temperature is 800-1400°C, including but not limited to 800°C, 1000°C, 1200°C, 1400°C, etc.; and the holding time is 5 min-30 min, including but not limited to 5 min, 10 min, 20 min, 30 min, etc. Within the scope of the present application, the composition and structure of the real cemented agglomerate rock can be obtained. The sintering temperature and pressure have a certain cooperative effect. When the maximum sintering temperature is set low, the effect of high-temperature sintering can be achieved by applying pressure, and the energy consumption can be reduced to a certain extent. However, if both the maximum sintering temperature and the pressure are too low, the minerals will not melt and the glass phase cannot be formed. If both the maximum sintering temperature and the pressure are too high, the minerals will all melt and the crystalline phase cannot be formed. At the same time, a long holding time does not meet the formation process of the real cemented agglomerate rock (i.e., the minerals melt instantaneously at high temperature after being hit by a meteorite, and then rapidly cool), and is not conducive to obtaining the composition and structure of the real cemented agglomerate rock. By changing the maximum sintering temperature, holding time, and uniaxial pressure value within a certain range, the glass phase / crystalline phase composition, nanomicrostructure such as vesicle size and number of the cemented agglomerate rock can be controlled.

[0033] In the present embodiment, the heating rate is 50-200°C, including but not limited to 50°C, 100°C, 150°C, 200°C, etc. By controlling the heating rate within the above range, the present application is more conducive to simulating the formation process of the cemented agglomerate rock in the real lunar soil (i.e., the minerals melt instantaneously at high temperature after being hit by a meteorite).

[0034] In the present embodiment, the rapid cooling is achieved by cooling the sintered product from the maximum sintering temperature to ≤100°C within 5 minutes.

[0035] In some specific embodiments of the present application, the liquid cooling chamber or cooling system provided with the discharge plasma sintering furnace is used to achieve rapid cooling by controlling the flow rate and temperature of the liquid cooling medium. The rapidly circulating cooling medium can rapidly absorb the heat of the material and accelerate the cooling process. In addition, the cooling process can also be accelerated by introducing inert gases (such as nitrogen or argon) into the furnace. These gases can effectively carry away the heat in the furnace, thereby rapidly reducing the temperature of the material.

[0036] In the present embodiment, the pressure is removed when the sintered product is rapidly cooled to a temperature <100°C after the high-temperature sintering process.

[0037] To avoid repetition, the raw materials used in the following examples and comparative examples of the present application are basalt, the particle size is ≤0.01 mm, and the chemical composition of the raw materials is obtained by X-ray fluorescence spectroscopy (XRF) analysis. The specific chemical oxide composition is shown in Table 1.

[0038] Table 1 Chemical oxide composition of raw materials (wt%)

[0039] SiO2 TiO2 Al2O3 FeO T ]]> MnO MgO CaO Na2O [K2O] P2O5 49.29 1.94 14.86 12.37 0.12 6.07 9.53 2.78 0.89 0.36

[0040] Example 1

[0041] 10 grams of raw material were poured into a graphite mold with an inner diameter of 20 mm, an outer diameter of 65 mm, and a graphite paper lining, and the raw material was pressed into a cylinder. Then, solid-phase sintering was performed in a spark plasma sintering furnace (SPS) of Shanghai Chenhua Scientific Instruments Co., Ltd. The sintering process was as follows: first step, the sintering temperature was raised to 700 ℃ at a heating rate of 100 ℃ per minute, and the power upper limit was set to 35%; second step, the sintering temperature was raised to 1400 ℃ at a heating rate of 100 ℃ per minute, and the power upper limit was set to 70%; third step, 6 min at 1400 ℃, and the power upper limit was set to 70%; the entire sintering was carried out under a nitrogen atmosphere, and a constant uniaxial pressure of 20 MPa was applied. After the end of the sintering process, the sintered sample was rapidly cooled, and the pressure was removed when the temperature of the graphite mold was <100 ℃. The obtained sample was in the shape of a cylinder with a diameter of 20 mm and a height of 5 mm, and finally the graphite debris on the surface of the sintered sample was removed.

[0042] Example 2

[0043] 10 grams of raw material were poured into a graphite mold with an inner diameter of 20 mm, an outer diameter of 65 mm, and a graphite paper lining, and the raw material was pressed into a cylinder. Then, solid-phase sintering was performed in a spark plasma sintering furnace (SPS) of Shanghai Chenhua Scientific Instruments Co., Ltd. The sintering process was as follows: first step, the sintering temperature was raised to 700 ℃ at a heating rate of 100 ℃ per minute, and the power upper limit was set to 35%; second step, the sintering temperature was raised to 1200 ℃ at a heating rate of 100 ℃ per minute, and the power upper limit was set to 70%; third step, 6 min at 1200 ℃, and the power upper limit was set to 70%; the entire sintering was carried out under a nitrogen atmosphere, and a constant uniaxial pressure of 10 MPa was applied. After the end of the sintering process, the sintered sample was rapidly cooled, and the pressure was removed when the temperature of the graphite mold was <100 ℃. The obtained sample was in the shape of a cylinder with a diameter of 20 mm and a height of 5 mm, and finally the graphite debris on the surface of the sintered sample was removed.

[0044] Comparative Example 1

[0045] 10 grams of the raw material were placed in a crucible and calcined in a box furnace at 1400℃, with air as the atmosphere and a temperature schedule of 10° / min. After being raised to 1400℃, the sample was directly removed from the box furnace and rapidly cooled by a fan.

[0046] Comparative Example 2

[0047] 10 grams of the raw material were placed in a crucible and calcined in a box furnace at 1200℃, with air as the atmosphere and a temperature schedule of 10° / min. After being raised to 1200℃, the sample was directly removed from the box furnace and rapidly cooled by a fan.

[0048] Performance testing

[0049] The agglomerated clastic rocks prepared in the examples and comparative examples were observed by X-ray diffractometer, scanning electron microscope and optical microscope, and the test results are shown in Figures 2-8 .

[0050] Referring to Figure 1 , Figure 1 is an optical micrograph of a thin section of agglomerated clastic rock in lunar soil from Apollo 17 sample. It can be seen from Figure 1 that there are vesicles in the agglomerated clastic rock of the real lunar soil.

[0051] Referring to Figure 2 , Figure 2 is an SEM image of the agglomerated clastic rock prepared in Example 1 of the present application. It can be seen from Figure 2 that the agglomerated clastic rock prepared in Example 1 of the present application has a certain number of vesicles of different sizes.

[0052] Referring to Figure 3 , Figure 3 is an electron microscope image of the agglomerated clastic rock prepared in Example 1 of the present application. It can be seen from Figure 3 that the agglomerated clastic rock prepared in Example 1 of the present application has a certain number of vesicles of different sizes.

[0053] Referring to Figure 4 , Figure 4 is an X-ray diffraction image of the agglomerated clastic rock prepared in Example 2 of the present application. It can be seen from Figure 4 that the agglomerated clastic rock prepared in Example 2 of the present application has a glass phase-crystalline phase composition.

[0054] Referring to Figure 5 , Figure 5 is an SEM image of the agglomerated clastic rock prepared in Example 2 of the present application. It can be seen from Figure 5 that the agglomerated clastic rock prepared in Example 2 of the present application has a certain number of vesicles of different sizes.

[0055] Referring to Figure 6 ,Figure 6 is an electron microscope image of the bound agglomerate rock prepared in Example 2 of the present application. The bound agglomerate rock prepared in Example 2 of the present application was observed under a scanning electron microscope (SEM) at 5000X magnification. Figure 6 As can be seen, the bound agglomerate rock prepared in Example 2 of the present application has a certain amount of vesicles of different sizes.

[0056] Figure 7 is an SEM image of the bound agglomerate rock prepared in Comparative Example 1 of the present application. The bound agglomerate rock prepared in Comparative Example 1 of the present application was observed under a scanning electron microscope (SEM) at 5000X magnification. Figure 7 As can be seen, the bound agglomerate rock prepared in Comparative Example 1 of the present application has not formed a vesicle structure.

[0057] Figure 8 is an SEM image of the bound agglomerate rock prepared in Comparative Example 2 of the present application. The bound agglomerate rock prepared in Comparative Example 2 of the present application was observed under a scanning electron microscope (SEM) at 5000X magnification. Figure 8 As can be seen, the bound agglomerate rock prepared in Comparative Example 2 of the present application has not formed a vesicle structure.

[0058] The above-described specific embodiments of the present application do not constitute a limitation on the protection scope of the present application. Any various other corresponding changes and modifications made according to the technical concept of the present application should be included within the protection scope of the present application.

Claims

1. A method for preparing a multi-physical field simulation of a cemented breccia in lunar soil, characterized in that, The method comprises the following steps: selecting raw materials similar to the chemical composition and mineral composition of real lunar soil; after the raw materials are pressed and formed, they are placed in a discharge plasma sintering furnace for high-temperature sintering, and then are rapidly cooled to obtain a bonded agglomerate rock; wherein during the high-temperature sintering, a uniaxial pressure of 5-40 MPa is applied, the temperature rising rate is 50-200 ℃, the highest sintering temperature is 800-1400 ℃, the holding time is 5 min-30 min, and the high-temperature sintering is carried out in a protective atmosphere; the rapid cooling is achieved by cooling the sintering product from the highest sintering temperature to ≤100 ℃ within 5 min.

2. The method according to claim 1, wherein the method is characterized by, The main rock type of the raw materials includes at least one of basalt, anorthosite and gabbro.

3. The method according to claim 1, wherein the method is characterized by, The particle size of the raw materials is ≤0.25 mm.

4. The method according to claim 1, wherein the method is characterized by, The protective atmosphere is at least one of nitrogen, helium and argon.

5. The method of claim 1, wherein the method further comprises: The protective atmosphere is introduced after the discharge plasma sintering furnace is evacuated to discharge air.

6. The method according to claim 5, wherein the method further comprises the step of: The vacuum degree is ≤20 Pa. ​ 7. The method according to claim 1, wherein the method is characterized by, After the high-temperature sintering is completed, the sintering product is rapidly cooled to a temperature <100 ℃, and then the pressure is released.

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