A high lithium density tritium breeding ceramic material, a preparation method and application thereof

Abstract

The application belongs to the technical field of nuclear materials, and specifically discloses a high-lithium-density Li6MnO4 tritium breeding ceramic material, a preparation method thereof and application. Raw materials Li2O and MnO powders are weighed according to a molar ratio of 3:1, high-purity Li6MnO4 solids are prepared through one-step solid-phase sintering, the Li6MnO4 solids are fully ground and sieved to obtain Li6MnO4 powders, and the Li6MnO4 powders are pressed into ceramic round sheets in a single-shaft hydraulic machine to obtain the Li6MnO4 tritium breeding ceramic material. The material prepared by the application has extremely high purity and excellent thermal stability within 1200 DEG C, and is suitable for nuclear fusion reactors. The preparation method of the application has good batch reproducibility, is easy to synthesize, has simple preparation process and is convenient for industrialization.

Description

Technical Field

[0001] This invention belongs to the field of nuclear materials technology, and relates to a high lithium density Li6MnO4 tritium breeding ceramic material, its preparation method and application. Background Technology

[0002] The deuterium-tritium (DT) reaction is considered one of the most promising solutions to the future energy crisis. Tritium, a key fuel in the DT reaction, is extremely rare in nature and must be produced artificially. The ideal strategy for the continuous operation of a fusion reactor is to achieve tritium self-sufficiency within the reactor, i.e., "tritium self-sufficiency." This function is primarily achieved by the tritium breeder blanket (TBB) surrounding the plasma chamber. The tritium breeder material within the blanket generates tritium by capturing fusion neutrons and reacting with lithium nuclei. Therefore, the tritium breeder is one of the core functional materials of a fusion reactor.

[0003] The lithium densities of currently mainstream tritium breeding ceramic materials such as Li₂TiO₃ and Li₄SiO₄ are approximately 0.43 g / cm³. 3 and 0.55 g / cm 3 However, its lithium density remains insufficient, posing a challenge to achieving tritium fuel self-sufficiency in fusion reactors. Therefore, developing novel ceramic tritium breeders with higher lithium density is a key research direction for improving the tritium breeder ratio (TBR) and achieving tritium self-sufficiency. Li6MnO4 has a lithium density as high as 0.69 g / cm³. 3 The theoretical lithium density shows great potential. However, there are currently significant technical bottlenecks in the synthesis and preparation of Li6MnO4 tritium-breeding ceramic materials: First, lithium evaporates at high temperatures, making it difficult to obtain pure phase products in solid-phase reactions; Second, the lack of clear process window (temperature, time) guidance can easily lead to problems such as incomplete reaction or abnormal grain growth. Third, the study of its thermal stability and whether it can be prepared into a high-density ceramic material are still unclear.

[0004] Therefore, there is an urgent need in this field to develop a method for preparing high lithium density Li6MnO4 tritium breeding ceramic materials and to clarify their thermal stability, so as to lay the foundation for their application in nuclear fusion reactors. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing high-purity Li6MnO4 powder, a method for preparing high-density ceramic green bodies from this powder, and to demonstrate the excellent thermal stability of the material. The material prepared by this invention has extremely high purity and quality, and exhibits excellent thermal stability up to 1200°C, making it suitable for nuclear fusion reactors.

[0006] A method for preparing a high lithium density Li6MnO4 tritium-breeding ceramic material includes the following steps: (1) Preparation of precursor: Weigh Li2O powder and MnO powder at a molar ratio of 3:1, and then ball-mill the Li2O powder and MnO powder in ethanol medium for at least 30 minutes to make them uniformly mixed and obtain the precursor; (2) Solid-state sintering: The precursor obtained in step (1) is placed in an Al2O3 crucible and placed in a protective atmosphere. The temperature is raised to 750-950℃ at a rate of not less than 10℃ / min for sintering reaction for 12-20 h to obtain the sintering reaction product. Then the product is cooled with the furnace. (3) Preparation of Li6MnO4 powder: The cooled sintering reaction product obtained in step (2) is ground and sieved through a 200-mesh sieve to obtain high-purity Li6MnO4 powder; (4) Li6MnO4 ceramic molding: The high-purity Li6MnO4 powder obtained in step (3) is pressed into a ceramic green body of Li6MnO4.

[0007] As a preferred technical solution of the present invention, in step (1), the purity of both Li2O powder and MnO powder is not less than 99.99 wt.%.

[0008] As a preferred technical solution of the present invention, in step (2), the protective atmosphere is a mixed gas with a volume percentage of 95% Ar-5% H2.

[0009] As a preferred technical solution of the present invention, in step (2), the sintering process is: sintering at 800~900℃ for 16~20 h.

[0010] As a further preferred technical solution of the present invention, in step (2), the sintering process is: sintering at a temperature of 850~875℃ for 16~20 h.

[0011] As a preferred technical solution of the present invention, in step (4), the pressing pressure is not less than 80 MPa and the holding time is not less than 30 s.

[0012] As a preferred technical solution of the present invention, the pressed Li6MnO4 ceramic green body is a ceramic disc with a diameter of no more than 12 mm and a height of no more than 10 mm.

[0013] A high lithium density Li6MnO4 tritium breeding ceramic material, characterized in that it is prepared using the method of the present invention.

[0014] An application of the high lithium density Li6MnO4 tritium breeding ceramic material of the present invention is to use the high lithium density Li6MnO4 tritium breeding ceramic material as a tritium breeding ceramic material in a nuclear fusion reactor.

[0015] As a preferred technical solution of the present invention, a ceramic blank is made from a high lithium density Li6MnO4 tritium breeding ceramic material, and the ceramic blank has an open structure.

[0016] Compared with the prior art, the present invention has the following obvious and prominent substantive features and significant advantages: 1. The method of the present invention adopts a conventional one-step solid-state sintering method, which has a simple process route, low equipment requirements, and is easy to achieve large-scale preparation.

[0017] 2. The method of the present invention effectively balances the contradiction between reaction completeness and lithium volatilization by controlling the sintering temperature and time, especially the sintering temperature of 850-875℃ and the time of 16-20 h, and successfully prepares high-purity Li6MnO4, solving the key problem of the difficulty in high-quality synthesis of this material.

[0018] 3. The Li6MnO4 prepared by the method of the present invention has a high lithium density, which provides a key material basis for improving the tritium breeding ratio (TBR); at the same time, the ceramic green body formed by the subsequent pressing of the method of the present invention forms an open-pore structure, which may have a positive impact on the tritium release performance.

[0019] 4. The method of this invention clarifies the thermal stability of the material in an inert atmosphere and its melting point of approximately 1228°C, achieving excellent thermal stability of Li6MnO4 within 1200°C, providing important data support for its safe application in the actual working conditions of fusion reactor blankets. Attached Figure Description

[0020] Figure 1 The diagram shows the mass loss of the precursor prepared by the preferred embodiment of the present invention after sintering.

[0021] Figure 2 The image shows the XRD pattern of high-purity Li6MnO4 powder prepared by the preferred embodiment of the present invention.

[0022] Figure 3 The image shows a TG-DSC image of high-purity Li6MnO4 powder prepared by the preferred embodiment of the present invention.

[0023] Figure 4 SEM image of Li6MnO4 ceramic green body prepared by the preferred embodiment of the present invention. Detailed Implementation

[0024] The above solution will be further explained below with reference to specific embodiments. The embodiments of the present invention are described in detail below: Example 1 High-purity Li₂O powder and MnO powder, both with a purity of 99.99 wt.%, were weighed and mixed at a molar ratio of 3:1, resulting in a total mass of 5 g of Li₂O powder and MnO powder. The mixed powder was then placed in a ball mill jar with ethanol and ball-milled at high energy for 30 min to ensure uniform mixing, thus obtaining the precursor.

[0025] The mixed precursors were then placed in an Al2O3 crucible and placed in a tube furnace. The furnace chamber was first evacuated, and then a 95% Ar-5% H2 mixture was introduced as a protective atmosphere. The temperature was increased to the target temperature (750℃, 800℃, 850℃, 875℃, 900℃, and 950℃, respectively) at a rate of 10℃ / min, and sintered at these temperatures for 12h, 16h, and 20h, respectively. After the reaction was completed, the furnace was cooled.

[0026] The sintering temperature and time conditions were as follows: 750℃, 12h; 800℃, 12h; 850℃, 12h; 875℃, 12h; 900℃, 12h; 950℃, 12h; 750℃, 16h; 800℃, 16h; 850℃, 16h; 875℃, 16h; 900℃, 16h; 950℃, 16h; 750℃, 20h; 800℃, 20h; 850℃, 20h; 875℃, 20h; 900℃, 20h; 950℃, 20h.

[0027] The sintered product was then ground and sieved through a 200-mesh sieve to obtain high-purity Li6MnO4 powder under different conditions.

[0028] The mass loss of the precursor prepared by the method in this embodiment after sintering through the above-mentioned different processes is as follows: Figure 1 As shown, temperature and time are the main factors affecting the products of solid-state sintering. Excessively high sintering temperatures and excessively long sintering times exacerbate the mass loss of the sintered products, while excessively low sintering temperatures and excessively short sintering times fail to improve the activity of the products or meet the quality requirements. In this embodiment, above 950℃ and for more than 20 hours, the mass loss after sintering increases significantly, while below 750℃ and for less than 12 hours, although the mass loss is very low, the sintering is insufficient, and the desired sintered product cannot be obtained.

[0029] like Figure 2 As shown, X-ray diffraction (XRD) analysis was performed on high-purity Li6MnO4 powder prepared under four sintering temperatures and times: 850℃, 16h; 850℃, 20h; 875℃, 16h; 875℃, 20h. The XRD analysis results indicate that high-purity Li6MnO4 powder can be successfully obtained by sintering at 850℃~875℃ for 16~20h.

[0030] In addition, Li6MnO4 powder with good purity and quality was also prepared under other temperature and time conditions in Example 1. The method in this example adopts a conventional one-step solid-state sintering method, which has a simple process route, low equipment requirements, and is easy to scale up. Example 2

[0031] The high-purity Li6MnO4 powder synthesized in Example 1 at 875℃ for 16 hours was subjected to TG-DSC testing under an argon atmosphere. Figure 3 As shown, Figure 3 (a) is the TG-DSC image of high-purity Li6MnO4 powder. Figure 3 (b) Appearance of high-purity Li6MnO4 powder before and after TG-DSC testing. The TG curve shows that the material is stable in quality when heated to 1500℃; the DSC curve shows a clear endothermic onset point at approximately 1228℃, which is determined to be the melting point (Tm) of Li6MnO4. Li6MnO4 exhibits excellent thermal and state stability at temperatures not exceeding 1200℃. Example 3

[0032] High-purity Li6MnO4 powder synthesized under different sintering conditions in Example 1 was placed into a cylindrical mold and pressed into a ceramic green body with a diameter of 12 mm and a height of 10 mm in a uniaxial hydraulic press at 80 MPa for 30 s. Its microstructure was observed. Figure 4 As shown. Figure 4 (a), 4(b), 4(c), and 4(d) are SEM images of Li6MnO4 ceramic green bodies under four sintering temperatures and times, respectively: 850℃, 16h; 850℃, 20h; 875℃, 16h; and 875℃, 20h. It can be seen that the prepared Li6MnO4 ceramic green bodies have uniform particle size and distribution, and uniform porosity.

[0033] In Example 3 of this invention, high-purity Li6MnO4 powder was successfully prepared through an optimized solid-state reaction process (850-875℃, 16-20h), and further sintered into a high-density, high-lithium-density ceramic green body. This material exhibits excellent high-temperature stability in an inert atmosphere, with a melting point as high as 1228℃, making it a highly promising candidate material for a novel high-lithium-density tritium breeding agent. The method described in the above examples of this invention effectively balances the contradiction between reaction completeness and lithium volatilization by controlling the sintering temperature and time, particularly preferably controlling the sintering temperature to 850-875℃ and the time to 16-20h, successfully preparing high-purity Li6MnO4 and solving the key problem of the difficulty in synthesizing this material with high quality. Example 4

[0034] The high lithium density Li6MnO4 tritium breeder ceramic material prepared using the methods described in the above embodiments can be used as a tritium breeder ceramic material for nuclear fusion reactors.

[0035] The lithium density of Li6MnO4 prepared by the method in this embodiment is close to 0.69 g / cm³. 3 This invention demonstrates great potential and represents an excellent option for tritium-breeding ceramic materials. The methods described above overcome the problem of lithium volatilization at high temperatures, which makes it difficult to obtain pure-phase products in solid-state reactions. This invention provides clear process windows (temperature, time) guidance, ensures complete reaction, and effectively addresses issues such as abnormal grain growth. In the development of a method for preparing high-lithium-density Li6MnO4 tritium-breeding ceramic materials, this invention specifically studied thermal stability, thereby ensuring the preparation of highly dense ceramic materials. The Li6MnO4 prepared by this invention has a high lithium density, providing a key material basis for improving the tritium breeding ratio (TBR). The preparation method of this invention exhibits good batch reproducibility, is easy to synthesize, has a simple preparation process, and is suitable for industrialization. Example 5

[0036] In this embodiment, a ceramic preform with an open-pore structure is fabricated from high-lithium-density Li6MnO4 tritium breeding ceramic material. This provides space for tritium release and may have a positive impact on tritium release performance. Therefore, the high-lithium-density Li6MnO4 tritium breeding ceramic material of this embodiment not only possesses excellent thermal stability, but its unique material structure also lays the foundation for its application in nuclear fusion reactors.

[0037] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high lithium density Li6MnO4 tritium-breeding ceramic material, characterized in that, Includes the following steps: (1) Preparation of precursor: Weigh Li2O powder and MnO powder at a molar ratio of 3:1, and then ball-mill the Li2O powder and MnO powder in ethanol medium for at least 30 minutes to make them uniformly mixed and obtain the precursor; (2) Solid-state sintering: The precursor obtained in step (1) is placed in an Al2O3 crucible and placed in a protective atmosphere. The temperature is raised to 750-950℃ at a rate of not less than 10℃ / min for sintering reaction for 12-20 h to obtain the sintering reaction product. Then the product is cooled with the furnace. (3) Preparation of Li6MnO4 powder: The cooled sintering reaction product obtained in step (2) is ground and sieved through a 200-mesh sieve to obtain high-purity Li6MnO4 powder; (4) Li6MnO4 ceramic molding: The high-purity Li6MnO4 powder obtained in step (3) is pressed into a ceramic green body of Li6MnO4.

2. The method for preparing high lithium density Li6MnO4 tritium-breeding ceramic material according to claim 1, characterized in that: In step (1), the purity of both Li2O powder and MnO powder is not less than 99.99 wt.%.

3. The method for preparing high lithium density Li6MnO4 tritium-breeding ceramic material according to claim 1, characterized in that: In step (2), the protective atmosphere is a mixture of gases with a volume percentage of 95% Ar and 5% H2.

4. The method for preparing high lithium density Li6MnO4 tritium-breeding ceramic material according to claim 1, characterized in that: In step (2), the sintering process is: sintering at 800~900℃ for 16~20 h.

5. The method for preparing high lithium density Li6MnO4 tritium-breeding ceramic material according to claim 4, characterized in that: In step (2), the sintering process is: sintering at 850~875℃ for 16~20 h.

6. The method for preparing high lithium density Li6MnO4 tritium-breeding ceramic material according to claim 1, characterized in that: In step (4), the pressing pressure is not less than 80 MPa and the holding time is not less than 30 s.

7. The method for preparing high lithium density Li6MnO4 tritium-breeding ceramic material according to claim 4, characterized in that: The pressed Li6MnO4 ceramic green body is a ceramic disc with a diameter not exceeding 12 mm and a height not exceeding 10 mm.

8. A high lithium density Li6MnO4 tritium breeding ceramic material, characterized in that: Prepared using the method described in any one of claims 1 to 7.

9. The application of the high lithium density Li6MnO4 tritium breeding ceramic material according to claim 8, characterized in that: The high lithium density Li6MnO4 tritium breeder ceramic material is used as a tritium breeder ceramic material for nuclear fusion reactors.

10. The application of the high lithium density Li6MnO4 tritium breeding ceramic material according to claim 9, characterized in that: High-lithium-density Li6MnO4 tritium-breeding ceramic material is used to make ceramic blanks with open-pore structures.

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