Preparation method of nano elemental iron in simulated lunar soil

Abstract

The invention provides a preparation method of nano elemental iron in simulated lunar soil, and belongs to the field of celestial body simulation materials. The preparation method of the nano elemental iron in the simulated lunar soil comprises the following steps: taking iron-containing mineral powder, heating to the highest temperature at the heating rate of more than or equal to 600 DEG C / s in a vacuum environment, and immediately cooling; the highest temperature is 2000-3500 DEG C, and the cooling rate is greater than or equal to 50 DEG C / s. The preparation process provided by the invention is simple and efficient, large-scale production can be realized, the preparation process reproduces the formation process of the nano elemental iron in the real lunar soil to a certain extent, and the prepared nano elemental iron has similar morphology and size with the nano elemental iron in the real lunar soil. By changing the temperature system, such as the highest heating temperature and the heating rate, the nano-micro structure, such as the size of the nano elemental iron, can be regulated and controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of celestial body simulation materials, and in particular to a method for preparing nano-elemental iron in simulated lunar soil. Background Art

[0002] In recent years, my country's aerospace science and technology has made rapid progress. Among them, the Chang'e-6 probe successfully completed the sampling mission in the South Pole-Aitken Basin on the far side of the moon, and returned to Earth safely with 1,935.3 grams of precious lunar samples. These samples have immeasurable scientific value in revealing the origin and evolution of the moon.

[0003] Lunar surface construction is a core strategic task for my country's future deep space exploration. However, due to the high cost of transportation from the Earth to the Moon, using lunar soil resources to prepare key structural materials and carry out in-situ construction on the lunar surface is an inevitable choice 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. It is a common practice at home and abroad to use earth minerals to develop simulated lunar soil similar to lunar soil. Therefore, the research and development of high-fidelity simulated lunar soil is a key foundation to support the research of in-situ construction materials on the moon. And there is a key component in the lunar soil-nano elemental iron, which is an important product of space weathering of lunar soil. It is widely present in cohesive agglomerates and distributed at the edges of lunar soil particles. The formation of nano-elemental iron originates from the weathering of the lunar soil by solar wind, cosmic rays and micrometeorite impacts. It converts Fe 2+ Reduction to Fe 0 , these Fe 0 The size of the particles is less than 1 μm, and most of them are tens to hundreds of nanometers in size, which has an important influence on the physical and chemical properties of the lunar soil.

[0004] However, the simulated lunar soil prepared in China so far lacks the key component, nano-elemental iron. Therefore, the preparation method of nano-elemental iron is still imperfect and requires further research and innovation. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present invention provides a method for preparing nano-elemental iron in simulated lunar soil, aiming to solve the technical problem that the key component nano-elemental iron is lacking in the existing simulated lunar soil components, and to improve the degree of similarity between the size and morphology of the prepared nano-elemental iron and the nano-elemental iron in the real lunar soil.

[0006] In a first aspect, the present invention provides a method for preparing nano-elemental iron in simulated lunar soil, comprising the following steps: Take iron-containing mineral powder, heat it to a maximum temperature at a heating rate of ≥600°C / s in a vacuum environment, and then cool it down immediately. The maximum temperature is 2000-3500°C, and the cooling rate is ≥30°C / s.

[0007] The present invention uses iron-containing minerals as raw materials, and rapidly heats the iron-containing minerals to high temperatures in a vacuum environment to reduce them to elemental iron. This simulates to a certain extent the process of real lunar soil converting Fe into Fe after high temperatures under the impact of solar wind, cosmic rays and micrometeorites. 2+ Reduction to Fe 0 After reaching a high temperature, the temperature is immediately lowered. This rapid temperature change can inhibit the recrystallization process of iron oxides, so that the iron atoms do not have time to rearrange to form a stable oxide structure, but solidify rapidly in the form of elemental iron, thereby obtaining nano-elemental iron with a smaller particle size.

[0008] Preferably, the iron-containing minerals include ilmenite and / or fayalite. The presence of ilmenite and fayalite, two iron-containing minerals, in real lunar soil is not only of great significance for understanding the geological history and evolution of the moon, but also has potential value for the exploration and utilization of lunar resources.

[0009] Preferably, the iron-containing mineral powder has a particle size of micrometers; more preferably, the iron-containing mineral powder has a particle size of ≤10 micrometers. A smaller particle size means a larger specific surface area, which helps to increase the contact area between the iron-containing mineral powder and the heat energy, thereby improving the reaction efficiency during the heating process.

[0010] Preferably, the vacuum environment has a pressure of ≤10 Pa. The vacuum condition is to provide a reducing environment on the one hand, and to simulate the high vacuum environment of the real moon on the other hand.

[0011] Preferably, the heating rate is ≥1200°C / s; more preferably, the heating rate is ≥2000°C / s. A higher heating rate can accelerate the thermal motion of atoms and promote the nucleation rate, so that iron atoms quickly aggregate to form nanoparticles. This rapid nucleation helps to obtain smaller and evenly distributed nanoparticles, thereby improving the uniformity and consistency of the material.

[0012] Preferably, the maximum temperature is 2500° C. to 3500° C.; more preferably, the maximum temperature is 2500° C. to 3000° C. When preparing nano-elemental iron, it is necessary to reasonably select the maximum temperature range according to specific application requirements and conditions to balance material performance and preparation cost.

[0013] Preferably, the cooling rate is ≥50°C / s; more preferably, the cooling rate is ≥100°C / s. Rapid cooling can inhibit the growth of grains, thereby obtaining finer nano-element iron particles.

[0014] There is no oxygen on the lunar surface, which is in a vacuum reducing environment. Taking ilmenite as an example, decomposition reaction of ilmenite will occur through high-temperature sintering, and FeTiO3 will decompose to produce iron, oxygen and titanium oxide.

[0015] The present invention places iron-containing mineral powder in a vacuum environment, and the material is rapidly heated to a temperature of 2000-3500°C, achieving the thermodynamic conditions for the iron-containing mineral to decompose into iron, and to a certain extent simulates the real lunar soil under the solar wind, cosmic rays and micrometeorite impact after high temperature to convert Fe 2+ Reduction to Fe 0 During the weathering process, after reaching the set high temperature, the material is rapidly cooled, which is conducive to the formation of smaller-sized nano-element iron, whose nano-microstructure is closer to the nano-element iron in real lunar soil.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention proposes a method for preparing nano-elemental iron in simulated lunar soil. An iron-containing mineral is selected as a raw material, and the iron-containing mineral is rapidly heated to a high temperature in a vacuum environment to decompose into elemental iron. After reaching a high temperature, the temperature is immediately and rapidly lowered. This rapid temperature change can inhibit the recrystallization process of iron oxides, so that the iron atoms do not have time to rearrange to form a stable oxide structure, but instead rapidly solidify in the form of elemental iron, thereby obtaining nano-elemental iron with a smaller particle size. By changing the temperature system such as the maximum heating temperature and the heating rate, the size and other nano-microstructures of the nano-elemental iron can be controlled. After heating to 2000~3500℃ at a heating rate of ≥800℃ / s and then immediately cooling, elemental iron with an average particle size of less than 100nm can be obtained.

[0017] (2) The preparation process of the present invention is simple, efficient, and can be mass-produced. The preparation process reduces iron-containing minerals to elemental iron in a high temperature and vacuum environment, which to a certain extent simulates the process in which real lunar soil is converted to Fe under the influence of solar wind, cosmic rays, and micrometeorite impacts. 2+ Reduction to Fe 0 The nanostructures of the prepared nano-element iron are closer to those of the nano-element iron in the real lunar soil, which is of great significance for the further preparation of high-fidelity simulated lunar soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD spectrum of nano-element iron in the simulated lunar soil prepared in Example 1 of the present invention; Figure 2 This is the XRD pattern of ilmenite in Example 1 of the present invention; Figure 3 This is a SEM image of nano-element iron in the simulated lunar soil prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0020] The experimental methods without specific conditions in the examples are usually carried out according to conventional conditions and conditions described in the manual, or according to conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0021] Example 1 0.1g of ilmenite powder (particle size ≤0.01mm) was placed in a Joule heating furnace, the vacuum degree was adjusted to 10Pa, and heating was carried out. The temperature was raised to 2741℃ at a heating rate of 1200℃ / s, and then immediately cooled to room temperature at a rate of 30℃ / s. The sample was then taken out to obtain the simulated nano-element iron in the lunar soil.

[0022] Example 2 Place 0.1g of fayalite powder (particle size ≤ 0.01mm) in a Joule heating furnace, adjust the vacuum degree to 10Pa, heat it, raise the temperature to 3500℃ at a heating rate of 1200℃ / s, and then immediately cool it to room temperature at a rate of 50℃ / s. Then take out the sample to obtain the simulated nano-element iron in the lunar soil.

[0023] Example 3 The difference between this embodiment and embodiment 1 is that the heating rate of the Joule heating furnace is 2000° C. / s, and the remaining steps are the same as those in embodiment 1.

[0024] Example 4 The difference between this embodiment and embodiment 1 is that the heating rate of the Joule heating furnace is 600° C. / s, and the remaining steps are the same as those in embodiment 1.

[0025] Example 5 The difference between this embodiment and embodiment 1 is that the cooling rate of the Joule heating furnace is 100° C. / s, and the remaining steps are the same as those in embodiment 1.

[0026] Comparative Example 1 The difference between this comparative example and Example 1 is that the particle size of the ilmenite powder is 0-0.1 mm, and the remaining steps are the same as those in Example 1.

[0027] Comparative Example 2 The difference between this comparative example and Example 1 is that the Joule heating furnace is heated to 1000° C., and the remaining steps are the same as those of Example 1. No peak of elemental iron is found by X-ray diffraction detection.

[0028] Comparative Example 3 The difference between this comparative example and Example 1 is that the heating rate of the Joule heating furnace is 200° C. / s, and the remaining steps are the same as those in Example 1.

[0029] Comparative Example 4 The difference between this comparative example and Example 1 is that the cooling rate of the Joule heating furnace is 10°C / s, and the remaining steps are the same as those in Example 1.

[0030] Comparative Example 5 The difference between this comparative example and Example 1 is that the Joule heating furnace is heated to 2741° C. and then kept warm for 30 seconds before cooling down. The remaining steps are the same as those in Example 1.

[0031] Test Case X-ray diffraction and scanning electron microscopy were used to characterize the nano-element iron in the simulated lunar soil prepared in the examples and comparative examples.

[0032] The XRD spectrum of nano-element iron in the simulated lunar soil prepared in Example 1 is as follows: Figure 1 As shown, the XRD pattern of the original ilmenite in Example 1 is as follows Figure 2 The XRD spectrum shows that the elemental iron was successfully prepared by the preparation method of the present invention. The scanning electron microscope image of the nano-elemental iron in the simulated lunar soil prepared in Example 1 is as follows: Figure 3 As shown in the figure, the sphere is nano-elemental iron. Scanning electron microscopy observation found that the average size of the generated elemental iron is less than 100nm.

[0033] The average particle size results of nano-elemental iron in the simulated lunar soil obtained in Examples 1 to 5 and Comparative Examples 1 to 5 are shown in Table 1.

[0034]

[0035] The results of Example 1 and Comparative Example 1 show that the particle size of the original iron-containing mineral has a great influence on the reduction effect. Smaller particle size means a larger specific surface area, which helps to increase the contact area between the iron-containing mineral powder and the heat energy, thereby improving the reaction efficiency during the heating process. The results of Example 1 and Comparative Example 2 show that the set maximum temperature has a great influence on the reduction effect. If the temperature is too low, the high temperature required for the decomposition of ilmenite may not be reached, resulting in incomplete decomposition and inability to effectively form zero-valent iron. The results of Example 1, Examples 3~4 and Comparative Example 3 show that the heating rate also has a great influence on the reduction effect. A fast heating rate helps to control the particle size and dispersibility of nanoparticles and avoid agglomeration, thereby obtaining nano-elemental iron with uniform particle size and consistent size with that in real lunar soil. The results of Example 1, Example 5 and Comparative Example 4 show that the cooling rate also has a great influence on the reduction effect. Rapid cooling can inhibit the growth of grains, thereby obtaining finer nano-elemental iron particles. The results of Example 1 and Comparative Example 5 show that too long a holding time at high temperature will lead to grain growth of nano-elemental iron. Although high temperature helps promote the reaction and form nanoparticles, too long a holding time will cause the already formed particles to continue to grow.

[0036] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, without departing from the scope of the main purpose of the present invention, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. A method for preparing nano-elemental iron in simulated lunar soil, characterized in that: The steps include: Take iron-containing mineral powder, heat it to the highest temperature at a heating rate of ≥600°C / s in a vacuum environment, and then cool it down immediately; the highest temperature is 2000-3500°C, and the cooling rate is ≥30°C / s.

2. The method for preparing nano-elemental iron in simulated lunar soil according to claim 1, characterized in that: The iron-containing minerals include ilmenite and / or fayalite.

3. The method for preparing nano-elemental iron in simulated lunar soil according to claim 1, characterized in that: The iron-containing mineral powder has a particle size of ≤10 microns.

4. The method for preparing nano-elemental iron in simulated lunar soil according to claim 1, characterized in that: The vacuum environment has a pressure of ≤10Pa.

5. The method for preparing nano-elemental iron in simulated lunar soil according to claim 1, characterized in that: The heating rate is ≥1200°C / s.

6. The method for preparing nano-elemental iron in simulated lunar soil according to claim 5, characterized in that: The heating rate is ≥2000°C / s.

7. The method for preparing nano-elemental iron in simulated lunar soil according to claim 1, characterized in that: The highest temperature is 2500°C~3500°C.

8. The method for preparing nano-elemental iron in simulated lunar soil according to claim 7, characterized in that: The highest temperature is 2500°C~3000°C.

9. The method for preparing nano-elemental iron in simulated lunar soil according to claim 1, characterized in that: The cooling rate is ≥50°C / s.

10. The method for preparing nano-elemental iron in simulated lunar soil according to claim 9, characterized in that: The cooling rate is ≥100°C / s.

Images