Lightweight microminiature reactor shielding material of tantalum-niobium coating boron carbide, preparation method and shielding component

Abstract

The invention relates to the technical field of reactor shielding materials, in particular to a tantalum-niobium coating boron carbide light-weight microminiature reactor shielding material, a preparation method and a shielding component. The reactor shielding material is obtained by taking boron carbide particles as an inner core and depositing a tantalum-niobium alloy coating on the surfaces of the boron carbide particles, the particle size of the boron carbide particles is 1-10 [mu] m; the thickness of the tantalum-niobium alloy coating ranges from 0.5 micrometer to 5 micrometers. The surfaces of the boron carbide particles are coated with the tantalum-niobium alloy coatings which are high in density, resistant to high temperature and high in gamma-ray absorption capacity, the gamma-ray protection capacity of the material is remarkably improved, and meanwhile the excellent neutron absorption performance of boron carbide is kept. In addition, the tantalum-niobium alloy coating can enhance the irradiation resistance and mechanical strength of the material, so that the problem that the traditional reactor shielding material is difficult to consider weight, irradiation resistance and neutron and ray protection capability is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of reactor shielding materials technology, specifically to a lightweight micro-scale reactor shielding material with tantalum-niobium coating and boron carbide, as well as its preparation method and shielding components. Background Technology

[0002] During nuclear reactor operation, a large number of neutrons and gamma rays are generated near the core, posing a significant threat to equipment and personnel safety. Traditional reactor shielding materials, such as lead, steel, or concrete, while highly effective at absorbing gamma rays, are typically dense, heavy, and lack sufficient radiation resistance. Structurally, they are not conducive to mobility or meeting lightweight requirements, particularly for space-constrained or weight-sensitive nuclear applications. With the development of miniaturized mobile reactors and aerospace nuclear energy systems, the demand for efficient and lightweight reactor shielding materials is increasing.

[0003] Lightweight, single-component neutron shielding materials, such as boron-containing polymers, boron carbide, or hydrogen-containing materials, are often used in control rods and shielding components due to their high neutron capture cross-section. However, their gamma-ray protection capability is limited, and they are prone to cracking or embrittlement under high-intensity irradiation, leading to structural degradation or performance decline.

[0004] Furthermore, in actual nuclear reactor operating environments, reactor shielding materials often need to withstand long-term exposure to high-energy neutrons and gamma rays, which places extremely high demands on the material's radiation resistance, thermal stability, and structural integrity. Existing shielding materials often cannot simultaneously meet these performance requirements.

[0005] Currently, researchers have developed boron carbide-based composite shielding materials, achieving lightweight shielding structures by mixing and pressing boron carbide powder with lightweight matrix materials. However, these composite shielding materials generally suffer from insufficient interfacial bonding, easily debonding during thermal cycling, leading to a decrease in the lifespan of the composite shielding materials; at the same time, the low atomic number of the matrix limits its gamma-ray shielding capability. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide, along with its preparation method and shielding components.

[0007] This invention significantly improves the gamma-ray shielding capability of boron carbide particles by coating them with a high-density, high-temperature resistant tantalum-niobium alloy coating that exhibits strong gamma-ray absorption. This coating also maintains the excellent neutron absorption performance of boron carbide. Furthermore, the tantalum-niobium alloy coating enhances the material's radiation resistance and mechanical strength, effectively addressing the limitations of traditional reactor shielding materials in terms of weight, radiation resistance, and neutron absorption. The challenge of balancing radiation protection capabilities.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows.

[0009] The first aspect of this invention provides a lightweight micro-scale reactor shielding material with a tantalum-niobium coated boron carbide core, which is obtained by depositing a tantalum-niobium alloy coating on the surface of boron carbide particles as the core; the particle size of the boron carbide particles is 1μm to 10μm; and the thickness of the tantalum-niobium alloy coating is 0.5μm to 5μm.

[0010] This invention uses boron carbide particles as the core and a tantalum-niobium alloy as the outer coating, with the two bonded together at the interface to form an integrated composite unit. Boron carbide, as the matrix, effectively shields thermal neutrons and some fast neutrons due to its excellent neutron absorption cross-section; the tantalum-niobium alloy coating provides a high atomic number and good radiation resistance, effectively enhancing the attenuation of gamma rays. This achieves functional synergy at the material level, thus realizing dual shielding against neutrons and gamma rays. Simultaneously, the alloying of tantalum and niobium maintains high gamma-ray protection while mitigating the excessive weight associated with single high-density metal materials such as tungsten or lead, achieving a balance between mechanical stability and lightweight design.

[0011] Specifically, the particle size of the boron carbide particles in the core component is preferably controlled within the range of 1μm to 10μm. This size ensures that the particles have sufficient specific surface area to achieve a tight bond with the metal alloy coating, and also helps to improve the overall density of the material during subsequent composite molding. At the same time, boron carbide itself is a lightweight, high-hardness ceramic material with an extremely high absorption cross section for thermal neutrons, thus enabling it to efficiently perform neutron absorption functions in the shielding unit.

[0012] A tantalum-niobium alloy coating with a thickness of 0.5 μm to 5 μm is deposited on the surface of boron carbide particles. This outer shell not only provides a continuous and dense protective barrier for the boron carbide particles, but also makes up for the deficiency of boron carbide's insufficient protection against gamma rays by scattering and absorbing gamma rays through high atomic number elements.

[0013] Preferably, in the tantalum-niobium alloy coating, the mass ratio of tantalum to niobium is 1 to 5:1. More preferably, in the tantalum-niobium alloy coating, the mass ratio of tantalum to niobium is 1.5 to 2:1.

[0014] To achieve a balance between density, shielding performance, and radiation resistance, the mass ratio of tantalum to niobium in tantalum-niobium alloy coatings is typically controlled between 1:1 and 5:1, with a ratio of approximately 6:4 exhibiting the best overall performance. This metallic coating not only provides gamma-ray shielding but also improves the bonding strength between particles during forming and service, reducing the risk of interfacial failure due to differences in thermal expansion coefficients or radiation damage.

[0015] Overall, the core-shell particle structure formed by this invention achieves an organic unity of lightweighting and multi-field radiation protection through the dual mechanism of "nuclear core absorption and gamma shielding of the outer shell," while improving the structural stability and service life of the material under complex irradiation environments.

[0016] Preferably, the tantalum-niobium alloy coating is formed by reacting tantalum salt and niobium salt in a hydrogen atmosphere using chemical vapor deposition, and then co-depositing the resulting tantalum and niobium onto the surface of boron carbide particles to form a tantalum-niobium alloy coating on the surface of the boron carbide particles.

[0017] A second aspect of this invention provides a method for preparing a lightweight micro-miniature reactor shielding material with a tantalum-niobium coating as described in the first aspect, comprising the following steps: Using boron carbide particles as the core, tantalum and niobium salts are reacted in a hydrogen atmosphere using chemical vapor deposition, and the resulting tantalum and niobium are co-deposited on the surface of boron carbide particles to form a tantalum-niobium alloy coating on the surface of boron carbide particles, thus obtaining a lightweight micro-scale reactor shielding material with tantalum-niobium coating boron carbide.

[0018] In terms of the preparation process, this invention employs a chemical vapor deposition method. Tantalum and niobium are co-deposited onto the surface of boron carbide particles by reacting chlorides, such as TaCl5 and NbCl5, with hydrogen in a high-temperature fluidized bed reactor, thereby forming a uniform, dense, and compositionally controllable alloy coating layer. This method effectively ensures the controllability of the coating thickness within the range of 0.5 μm to 5 μm and is suitable for mass production, particularly for n-γ composite protective materials requiring high coating continuity and uniformity.

[0019] Preferably, the tantalum salt is tantalum chloride; the niobium salt is niobium chloride.

[0020] Preferably, the hydrogen flow rate is 150 mL / min to 300 mL / min.

[0021] The third aspect of the present invention provides a shielding component, which is obtained by hot pressing or sintering the lightweight micro-small reactor shielding material with tantalum-niobium coating and boron carbide as described in the first aspect, and then curing it to obtain the shielding component.

[0022] Preferably, the conditions for the hot pressing process are: pressure 20MPa~40MPa, temperature 150℃~200℃; and the conditions for the sintering process are: temperature 1000℃~1200℃.

[0023] The shielding component can be plate-shaped or block-shaped.

[0024] This invention utilizes a shielding component composed of coated core-shell particles. The coated core-shell particles can be directly formed into a block or plate-shaped shield by hot pressing or sintering, or they can be combined with a lightweight composite matrix to maintain lightweight and high mechanical strength.

[0025] A fourth aspect of this invention provides a shielding component, which is obtained by uniformly mixing the lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide as described in the first aspect with a matrix material, and then hot-pressing or sintering it to uniformly disperse the lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide in the matrix material. After curing, a shielding component is obtained; the matrix material is an aluminum alloy or a resin matrix. In this invention, the aluminum alloy can be 6061 aluminum alloy; the resin matrix can be phenolic resin.

[0026] Preferably, the conditions for the hot pressing process are: pressure 20MPa~40MPa, temperature 150℃~200℃; and the conditions for the sintering process are: temperature 1000℃~1200℃.

[0027] Preferably, the density of the shielding component is 2.5 g / cm³. 3 ~4.5g / cm 3 The shielding component can be plate-shaped or block-shaped.

[0028] The beneficial effects of this invention are: 1. This invention significantly improves the gamma-ray protection capability of boron carbide particles by coating them with a high-density, high-temperature resistant tantalum-niobium alloy coating that exhibits strong gamma-ray absorption. An average thickness of 1 cm achieves a gamma-ray attenuation rate of approximately 75%, while maintaining the excellent neutron absorption performance of boron carbide. Furthermore, the tantalum-niobium alloy coating enhances the material's radiation resistance and mechanical strength, effectively solving the challenge of balancing weight, radiation resistance, and neutron and gamma-ray protection capabilities in traditional reactor shielding materials.

[0029] 2. Regarding lightweight design, this invention optimizes the thickness of the tantalum-niobium alloy coating and the size of the boron carbide particles, thereby controlling the composite density of the shielding component prepared from the lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide to 2.5 g / cm³. 3 ~4.5g / cm 3 While ensuring efficient shielding against neutrons and gamma rays, it achieves significant lightweight characteristics.

[0030] 3. Regarding interface stability and radiation resistance, this invention achieves a dense bond between the tantalum-niobium alloy coating and boron carbide particles. Simultaneously, the tantalum-niobium alloy coating can effectively suppress the embrittlement and volume expansion effects of boron carbide particles during irradiation, thereby extending the service life of the material under high-flux irradiation environments.

[0031] 4. In terms of shielding performance, this invention fully utilizes the neutron absorption effect of boron carbide particles and combines it with the gamma-ray protection effectiveness of the tantalum-niobium alloy coating to achieve a synergistic effect of dual shielding, enabling the material to achieve excellent comprehensive shielding performance with relatively small thickness.

[0032] 5. Regarding process controllability and large-scale production, the deposition process of tantalum-niobium alloy coatings is mature, with uniform thickness and strong controllability, making it suitable for industrial preparation and large-scale application. This invention not only effectively solves the problems of large weight, poor interface stability, and complex processes of existing advanced shielding materials, but also achieves a comprehensive improvement in overall performance in terms of lightweighting, shielding performance, and radiation resistance stability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the manufacturing process of the shielding component provided in the embodiments of the present invention.

[0034] Figure 2 These are schematic diagrams of the lightweight micro-small reactor shielding material with tantalum-niobium coating and boron carbide coating provided in the embodiments of the present invention, and the shielding member made by hot pressing the lightweight micro-small reactor shielding material with tantalum-niobium coating and boron carbide coating. Specifically, (a) is a schematic diagram of the lightweight micro-small reactor shielding material with tantalum-niobium coating and boron carbide coating; and (b) is a schematic diagram of the shielding member made by hot pressing the lightweight micro-small reactor shielding material with tantalum-niobium coating and boron carbide coating.

[0035] Figure 3 This is the shielding performance curve of shielding component B1, which is made by hot pressing of a lightweight micro-small reactor shielding material with tantalum-niobium coating and boron carbide coating, in Application Example 2 of the present invention, against neutrons / photons.

[0036] Figure 4 This is the shielding performance curve of the shielding component D1, which is made by hot pressing boron carbide in Comparative Example 1 of this invention, against neutrons / photons.

[0037] Explanation of reference numerals in the attached figures: 101. Boron carbide particles; 102. Tantalum-niobium alloy coating; 301. Plate-shaped shielding material; 302. Lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Boron carbide has significant advantages as a neutron shielding material, such as having an extremely high neutron trapping cross section, as well as high hardness and low density (approximately 2.50 g / cm³). 3 Therefore, boron carbide is widely used in key components of nuclear reactors, such as control rods and shielding blocks. However, boron carbide is a brittle ceramic, prone to cracking and embrittlement under high-intensity irradiation. It also has limited shielding capabilities against gamma rays, failing to provide comprehensive protection. Furthermore, under high-temperature irradiation, boron carbide may experience lattice expansion and embrittlement, affecting its service life.

[0041] To improve the performance of boron carbide, researchers have developed boron carbide-based composite shielding materials. These materials are created by mixing and pressing boron carbide powder with a lightweight matrix material to achieve a lightweight shielding structure. However, these composite materials generally suffer from insufficient interfacial bonding, making them prone to debonding during thermal cycling and leading to a decreased shielding material lifespan. Furthermore, the low atomic number of the matrix limits its gamma-ray shielding capability. Uneven distribution of boron carbide within the matrix can also create localized weak shielding areas.

[0042] In addition, some researchers have used boron carbide to construct composite materials, which improve toughness and increase neutron absorption rate through polymer matrix. However, polymer materials have poor temperature resistance and are prone to aging and carbonization in the high temperature environment of reactors, resulting in insufficient gamma shielding performance and limited mechanical strength.

[0043] Furthermore, in actual nuclear reactor operating environments, reactor shielding materials often need to withstand long-term exposure to high-energy neutrons and gamma rays, which places extremely high demands on the material's radiation resistance, thermal stability, and structural integrity, and existing materials often cannot meet these requirements.

[0044] The existing technical solutions generally suffer from the following structural defects: lightweighting and efficient shielding are difficult to achieve simultaneously; traditional heavy metal shielding, while offering strong gamma protection, is excessively heavy; lightweight materials, while reducing weight, provide insufficient gamma protection; and radiation resistance is inadequate. Its composite materials are prone to embrittlement or failure under the action of high-flux neutrons and gamma rays; the interface structure is unstable, and some composite materials have problems of interface debonding and thermal stress concentration.

[0045] To address the aforementioned problems, this invention provides a lightweight micro-scale reactor shielding material with a tantalum-niobium coated boron carbide core, along with its preparation method and shielding components. The shielding mechanism of this invention is manifested in the following ways: the boron carbide core has an extremely high capture cross-section for thermal neutrons, enabling efficient absorption of neutron radiation; the tantalum-niobium coating has a high atomic number, effectively attenuating gamma rays and compensating for the shortcomings of boron carbide in gamma protection; the tantalum and niobium alloy layer protects the particles, improving the structural stability of the material under high-temperature, high-flux irradiation environments and reducing interfacial cracking and irradiation embrittlement. Ultimately, this results in a composite shielding material that combines lightweight design, high-efficiency shielding, and long-term service stability.

[0046] like Figure 1 The diagram illustrates a schematic flow chart of the fabrication process for the shielding component. Specifically, the lightweight micro-reactor shielding material of the present invention, with tantalum-niobium coated boron carbide, uses boron carbide particles 101 as a core, and obtains it by depositing a tantalum-niobium alloy coating 102 on the surface of the boron carbide particles 101. Figure 2 (a). The lightweight micro-miniature reactor shielding material 302 of the present invention, which is tantalum-niobium coated boron carbide, can be prepared into a block or plate-shaped shielding component 301 by hot pressing or sintering, such as... Figure 2 (b) During the forming process, the coating particles come into contact with each other to form a densely packed structure. The coating not only provides gamma-ray shielding capability, but also forms mechanical bridging between particles, enhancing the mechanical strength of the overall structure.

[0047] Furthermore, the tantalum-niobium coated boron carbide particles of the present invention can be combined with lightweight composite matrix materials to prepare bulk or plate-shaped shielding components to meet the structural and shielding requirements of different reactors or nuclear energy systems. Preferred composite matrices include aluminum alloys and resin matrices, where aluminum alloys are suitable for shielding components with high load-bearing structural requirements or high-temperature environments, while resin matrices are suitable for scenarios requiring lightweight and easy processing. During the preparation process, the tantalum-niobium coated boron carbide particles can be uniformly dispersed in the matrix to form a uniformly distributed particle-matrix structure. The particles form a multi-point load-bearing and shielding unit network in the matrix, effectively improving the overall mechanical properties of the material while ensuring neutron and shielding... Uniform shielding effect of rays.

[0048] When preparing bulk or plate-shaped components, an appropriate forming method can be selected based on the matrix type. For example, for aluminum-based composites, powder metallurgy, hot isostatic pressing, or extrusion molding processes can be used to tightly bond the coating particles with the aluminum matrix at high temperatures, forming a dense composite bulk. For resin-based composites, molding or lamination processes can be used to uniformly distribute particles in the resin system, and then curing can form plate-shaped or sheet-shaped shielding components. In this process, the core-shell structure of the coating particles effectively prevents boron carbide from becoming brittle during processing or curing. Simultaneously, the good interfacial bonding between the coating and the matrix resists thermal stress and radiation stress concentration. This achieves both lightweight requirements and maintains high mechanical strength and service stability.

[0049] The composite density of the material in this invention is controlled at 2.5 g / cm³. 3 ~4.5g / cm 3 Compared to traditional lead and steel structures, this material significantly reduces weight and maintains high durability under multi-field coupled irradiation. Therefore, the technical solution of this invention not only overcomes the limitation of existing shielding materials in achieving both lightweight and efficient shielding, but also improves radiation resistance stability and service life through rational structural design, providing a novel shielding material that combines lightweight and high performance.

[0050] The technical solution of the present invention will be further described below through specific embodiments.

[0051] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.

[0052] Example 1 A method for preparing a lightweight micro-scale reactor shielding material with a tantalum-niobium coating and boron carbide coating includes the following steps: Using boron carbide particles with a particle size of 1μm to 10μm as the core, tantalum salt and niobium chloride are reacted in a hydrogen atmosphere by chemical vapor deposition, and the resulting tantalum and niobium are co-deposited on the surface of boron carbide particles to form a tantalum-niobium alloy coating with a thickness of 0.5μm on the surface of boron carbide particles, thus obtaining a lightweight micro-small reactor shielding material with tantalum-niobium coating boron carbide.

[0053] Boron carbide particles with a diameter of 2 μm were used as the core. The boron carbide particles were placed in a chemical vapor deposition (CVD) furnace, and the vacuum was increased to 1 × 10⁻⁶. -2 Pa ~ 1×10 -3The reactor was evacuated and purged with high-purity hydrogen for 2-3 cycles to remove residual air and moisture. Hydrogen gas (flow rate: 200 mL / min) was introduced at 950 °C, along with tantalum salt precursors tantalum pentachloride (TaCl5, evaporation temperature 250 °C, carrier gas hydrogen flow rate 50 mL / min) and niobium chloride (NbCl5, evaporation temperature 230 °C, carrier gas hydrogen flow rate 50 mL / min). The reaction time was controlled to 60 min, resulting in a tantalum-niobium alloy coating approximately 0.5 μm thick deposited on the surface of boron carbide particles, yielding a lightweight micro-scale reactor shielding material with a tantalum-niobium coating on boron carbide.

[0054] Example 2 A method for preparing a lightweight micro-scale reactor shielding material with a tantalum-niobium coating and boron carbide coating includes the following steps: Using boron carbide particles with a particle size of 1μm to 10μm as the core, tantalum chloride and niobium chloride are reacted in a hydrogen atmosphere by chemical vapor deposition, and the resulting tantalum and niobium are co-deposited on the surface of boron carbide particles to form a tantalum-niobium alloy coating with a thickness of 1.5μm on the surface of boron carbide particles, thus obtaining a lightweight micro-small reactor shielding material with tantalum-niobium coating boron carbide.

[0055] Boron carbide particles with a diameter of 3 μm were used as the core. The boron carbide particles were placed in a chemical vapor deposition (CVD) furnace, and a vacuum of 1 × 10⁻⁶ was applied. -2 Pa ~ 1×10 -3 The reactor was evacuated and purged with high-purity hydrogen for 2-3 cycles to remove residual air and moisture. Hydrogen gas (flow rate: 200 mL / min) was introduced at 1000℃, along with tantalum salt precursors tantalum pentachloride (TaCl5, evaporation temperature 250℃, carrier gas hydrogen flow rate 50 mL / min) and niobium chloride (NbCl5, evaporation temperature 230℃, carrier gas hydrogen flow rate 50 mL / min). The reaction time was controlled at 90 min, resulting in a tantalum-niobium alloy coating approximately 1.5 μm thick deposited on the surface of boron carbide particles, yielding a lightweight micro-scale reactor shielding material with a tantalum-niobium coated boron carbide.

[0056] Example 3 A method for preparing a lightweight micro-scale reactor shielding material with a tantalum-niobium coating and boron carbide coating includes the following steps: Using boron carbide particles with a particle size of 1μm to 10μm as the core, tantalum chloride and niobium chloride are reacted in a hydrogen atmosphere by chemical vapor deposition, and the resulting tantalum and niobium are co-deposited on the surface of boron carbide particles to form a tantalum-niobium alloy coating with a thickness of 2μm on the surface of boron carbide particles, thus obtaining a lightweight micro-small reactor shielding material with tantalum-niobium coating boron carbide.

[0057] Boron carbide particles with a diameter of 5 μm were used as the core. The boron carbide particles were placed in a chemical vapor deposition (CVD) furnace, and a vacuum of 1 × 10⁻⁶ was applied. -2 Pa ~ 1×10 -3 The reactor was evacuated and purged with high-purity hydrogen for 2-3 cycles to remove residual air and moisture. Hydrogen gas (flow rate: 200 mL / min) was introduced at 1050 °C, along with tantalum salt precursors tantalum pentachloride (TaCl5, evaporation temperature 250 °C, carrier gas hydrogen flow rate 50 mL / min) and niobium chloride (NbCl5, evaporation temperature 230 °C, carrier gas hydrogen flow rate 50 mL / min). The reaction time was controlled at 120 min, resulting in a tantalum-niobium alloy coating approximately 2 μm thick deposited on the surface of boron carbide particles, yielding a lightweight micro-scale reactor shielding material with a tantalum-niobium coated boron carbide.

[0058] Example 4 A method for preparing a lightweight micro-scale reactor shielding material with a tantalum-niobium coating and boron carbide coating includes the following steps: Using boron carbide particles with a particle size of 1μm to 10μm as the core, tantalum chloride and niobium chloride are reacted in a hydrogen atmosphere by chemical vapor deposition, and the resulting tantalum and niobium are co-deposited on the surface of boron carbide particles to form a tantalum-niobium alloy coating with a thickness of 3μm on the surface of boron carbide particles, thus obtaining a lightweight micro-small reactor shielding material with tantalum-niobium coating boron carbide.

[0059] Boron carbide particles with a diameter of 7 μm were used as the core. The boron carbide particles were placed in a chemical vapor deposition (CVD) furnace, and the vacuum was increased to 1 × 10⁻⁶. -2 Pa ~ 1×10 -3 The reactor was evacuated and purged with high-purity hydrogen for 2-3 cycles to remove residual air and moisture. Hydrogen gas (flow rate: 200 mL / min) was introduced at 1100 °C, along with tantalum salt precursors tantalum pentachloride (TaCl5, evaporation temperature 250 °C, carrier gas hydrogen flow rate 50 mL / min) and niobium chloride (NbCl5, evaporation temperature 230 °C, carrier gas hydrogen flow rate 50 mL / min). The reaction time was controlled at 150 min, resulting in a tantalum-niobium alloy coating approximately 3 μm thick deposited on the surface of boron carbide particles, yielding a lightweight micro-scale reactor shielding material with a tantalum-niobium coated boron carbide.

[0060] Example 5 A method for preparing a lightweight micro-scale reactor shielding material with a tantalum-niobium coating and boron carbide coating includes the following steps: Using boron carbide particles with a particle size of 1μm to 10μm as the core, tantalum chloride and niobium chloride are reacted in a hydrogen atmosphere by chemical vapor deposition, and the resulting tantalum and niobium are co-deposited on the surface of boron carbide particles to form a tantalum-niobium alloy coating with a thickness of 5μm on the surface of boron carbide particles, thus obtaining a lightweight micro-small reactor shielding material with tantalum-niobium coating boron carbide.

[0061] Boron carbide particles with a diameter of 10 μm were used as the core. The boron carbide particles were placed in a chemical vapor deposition (CVD) furnace, and a vacuum of 1 × 10⁻⁶ was applied. -2 Pa ~ 1×10 -3 The reactor was evacuated and purged with high-purity hydrogen for 2-3 cycles to remove residual air and moisture. Hydrogen gas was introduced at 1150℃ (flow rate: 200 mL / min), along with tantalum salt precursors tantalum pentachloride (TaCl5, evaporation temperature 250℃, carrier gas hydrogen flow rate 50 mL / min) and niobium chloride (NbCl5, evaporation temperature 230℃, carrier gas hydrogen flow rate 50 mL / min). The reaction time was controlled at 200 min, resulting in a tantalum-niobium alloy coating approximately 5 μm thick deposited on the surface of boron carbide particles, yielding a lightweight micro-scale reactor shielding material with a tantalum-niobium coated boron carbide.

[0062] The lightweight micro-small reactor shielding material with tantalum-niobium coating and boron carbide prepared in Examples 1 to 5 above was used as raw material to prepare shielding components and to test the shielding performance.

[0063] In the following application examples, the shielding component is a lightweight micro-small reactor shielding material with tantalum-niobium coating boron carbide, which is formed by hot pressing or sintering and then cured to obtain the shielding component.

[0064] Alternatively, the shielding component is formed by uniformly mixing a lightweight micro-reactor shielding material with a tantalum-niobium coated boron carbide layer with a matrix material, followed by hot pressing or sintering to ensure that the lightweight micro-reactor shielding material with the tantalum-niobium coated boron carbide layer is uniformly dispersed in the matrix material. After curing, the shielding component is obtained. The matrix material is an aluminum alloy or a resin matrix. The aluminum alloy can be 6061 aluminum alloy; the resin matrix can be phenolic resin. The matrix material can be selected according to actual needs.

[0065] Specifically, the hot-pressing process conditions are: pressure of 20MPa~40MPa and temperature of 150℃~200℃; the sintering process conditions are: temperature of 1000℃~1200℃. Under these hot-pressing and sintering conditions, a corresponding shielding component can be prepared; and the density of the shielding component is 2.5g / cm³. 3 ~4.5g / cm 3 The shielding components can be plate-shaped or block-shaped.

[0066] All shielding components mentioned below are plate-shaped, 15cm thick, and 50cm x 50cm in length and width. Application Example 1 A shielding component is a lightweight micro-reactor shielding material with a tantalum-niobium coating and boron carbide as described in Examples 1-5, formed by hot pressing. The primary principles are maintaining the integrity of the tantalum-niobium alloy coating and preventing elemental diffusion or chemical reactions between tantalum, niobium, and boron carbide at high temperatures. A low-temperature, short-time hot pressing process is employed. Taking Al as an example, after pre-pressing in a mold under vacuum or an inert atmosphere, it is hot-pressed and cured at 180°C. The hot-pressing pressure is controlled at 40 MPa, the heating rate is 2°C / min to 5°C / min, and the holding time is 60 min to 90 min. Under these conditions, the resin is fully cured, forming a dense bond between particles, but the temperature is far below the threshold for significant diffusion or reaction between the tantalum-niobium layer and the boron carbide matrix, thus effectively maintaining the integrity of the coating. After curing, the material is slowly cooled and depressurized to obtain a plate-shaped shielding component with a dense structure, stable interface, and continuous and complete coating. This shielding component combines the scattering and absorption capabilities of tantalum-niobium alloy for high-energy neutrons and gamma rays with the high absorption cross-section of boron carbide for thermal neutrons. It has excellent overall shielding performance and a stable structure, meeting the requirements for reactor shielding.

[0067] Table 1. Fabrication parameters of shielding components Note: The shielding material is a lightweight micro-reactor shielding material with a tantalum-niobium coating and boron carbide coating. For ease of explanation, it is simply referred to as the shielding material. The number refers to the number of the shielding component.

[0068] Application Example 2 A shielding component is prepared by hot pressing after uniformly mixing the lightweight micro-small reactor shielding material with tantalum-niobium coating boron carbide (Examples 1-5) with the base material at a mass ratio of 60:40.

[0069] Taking B1 material as an example, in the preparation process, tantalum-niobium coated boron carbide powder is first mixed with aluminum alloy powder. During the mixing process, the mixture is slowly stirred under an inert atmosphere to ensure that the tantalum-niobium coated boron carbide particles are uniformly dispersed in the aluminum alloy powder and to avoid coating damage. The mixture is then placed in a hot press mold and heated to 200°C under vacuum or high-purity argon protection, with a pressure of 33 MPa applied. The heating rate is controlled at 2°C / min to 5°C / min, and the pressure is held at the target temperature for 60 to 90 minutes. This allows the aluminum matrix to achieve plastic flow and dense bonding between particles at a lower temperature, while maintaining the integrity of the tantalum-niobium alloy coating. This process ensures good formability of the aluminum alloy while effectively preventing diffusion reactions between tantalum, niobium, and boron carbide, ensuring coating interface stability.

[0070] By filling the shielding component with a high proportion (60 wt%) of tantalum-niobium coated boron carbide material, the overall shielding capability against neutrons and gamma rays is significantly improved while maintaining high mechanical properties. Specifically, the boron carbide... 10 Boolean isotopes exhibit strong absorption of thermal neutrons, while tantalum and niobium, with their high atomic numbers and densities, effectively attenuate gamma rays and fast neutron energies. The aluminum matrix provides excellent thermal conductivity and structural support, resulting in good heat dissipation and stability of the shielding components under high-flux irradiation conditions in nuclear reactors.

[0071] Table 2. Fabrication parameters of shielding components Note: The shielding material is a lightweight micro-reactor shielding material with a tantalum-niobium coating and boron carbide coating. For ease of explanation, it is simply referred to as the shielding material. The number refers to the number of the shielding component.

[0072] Application Example 3 A shielding component is prepared by hot pressing and sintering a lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide (as described in Examples 1-5) at a mass ratio of 70:30, using phenolic resin as the matrix material. To ensure optimal shielding performance while maintaining structural integrity, J201 phenolic resin is selected as the matrix material. This phenolic resin exhibits excellent thermal carbonization properties, enabling the formation of a continuous carbonaceous framework at high temperatures, which enhances the thermal stability and neutron moderation capability of the composite.

[0073] Taking C1 material as an example, in the preparation process, tantalum-niobium coated boron carbide powder and phenolic resin powder are first mixed uniformly under an inert atmosphere. During mixing, a low-speed mechanical stirrer or planetary mixer is used for 30-60 minutes to prevent damage to the coating structure. The mixture is then placed into a mold for hot pressing. During the hot pressing stage, the temperature is gradually increased to 200℃ and a pressure of 30-40MPa is applied, held for 30 minutes to complete the initial curing and shaping of the resin. Afterwards, sintering is carried out under a vacuum or high-purity argon atmosphere, with the heating rate controlled at 3℃ / min-5℃ / min, finally reaching 1200℃ and holding for 2 hours to promote the full carbonization of the phenolic resin to form a high-strength carbon-based skeleton, while ensuring a stable bond between the tantalum-niobium coating and the boron carbide particles. During the cooling stage, the temperature is lowered to room temperature at a rate of 5℃ / min before demolding, resulting in a dense, fully coated plate-shaped shielding component.

[0074] Under these process conditions, the carbon-based continuous phase generated by the carbonization of phenolic resin can effectively encapsulate tantalum-niobium coated boron carbide particles, forming a multi-scale shielding interface layer; the boron carbide... 10Bode isotopes have a strong absorption effect on thermal neutrons, while tantalum and niobium alloy coatings can effectively attenuate gamma rays and high-energy neutrons, enabling the composite system to achieve efficient shielding against radiation in multiple energy regions.

[0075] Table 3. Fabrication parameters of shielding components Note: The shielding material is a lightweight micro-reactor shielding material with a tantalum-niobium coating and boron carbide coating. For ease of explanation, it is simply referred to as the shielding material. The number refers to the number of the shielding component.

[0076] Application Comparative Example 1 A boron carbide particle-reinforced aluminum-based composite shielding component uses 6061 aluminum alloy as the matrix material. Boron carbide powder is pre-cleaned and dried with alcohol, then mixed uniformly with the matrix material to ensure uniform dispersion of boron carbide within the matrix material, resulting in a mixture. The boron carbide accounts for 30 wt% of the mixture. The mixture is then pre-oxidized at 420℃ for 1 hour, followed by holding at 500℃ for 30 minutes. Finally, it is sintered using a vacuum hot-pressing method at 650℃, 120 kJ / min for 60 minutes. After curing, a plate-shaped shielding component, denoted as D1, is obtained.

[0077] The following comparison examines the fast neutron and fast photon shielding performance of shielding component B1 with that of material D1 of the same size. The results are as follows: Figure 3 and Figure 4 As shown.

[0078] Figure 3 This is the neutron / photon shielding performance curve of shielding component B1, fabricated by hot pressing using a lightweight micro-miniature reactor shielding material with a tantalum-niobium coating, as described in Application Example 2 of this invention. The lightweight micro-miniature reactor shielding material with a tantalum-niobium coating is referred to simply as the tantalum-niobium-coated boron carbide reactor shielding material.

[0079] Figure 4 This is the shielding performance curve of the shielding component D1, which is made by hot pressing boron carbide in Comparative Example 1 of this invention, against neutrons / photons.

[0080] like Figure 3As shown, shielding component B1 has a design life exceeding 10 years and exhibits excellent performance in radiation resistance and mechanical stability. To evaluate the shielding performance of shielding component B1 under high-energy radiation environments, it was systematically compared with D1. Experimental results show that under fast neutron energy spectrum (1MeV~10MeV), the linear attenuation coefficient of the tantalum-niobium coated boron carbide material is significantly higher than that of D1, with a corresponding linear attenuation rate of not less than 16% / cm, demonstrating excellent neutron absorption capability. Simultaneously, under fast gamma irradiation, its linear attenuation coefficient is also significantly better than that of D1, with a corresponding linear attenuation rate of not less than 75% / cm, reflecting the enhancing effect of the high-Z metal coating in gamma-ray shielding.

[0081] By comparing the two types of radiation, the lightweight micro-miniature reactor shielding material with tantalum-niobium coating in this embodiment of the invention shows higher attenuation efficiency in multi-energy radiation protection. This indicates that, with the same geometric thickness, the material can achieve efficient attenuation of both neutrons and gamma rays, thus significantly outperforming conventional boron carbide and verifying its application potential as a reactor shielding material.

[0082] After long-term irradiation, shielding component B1 exhibits stable mechanical properties, with an impact toughness change of ≤5% and a weight loss rate controlled within 0.5%, ensuring its structural integrity. Furthermore, this shielding component also possesses the advantages of high temperature resistance and low density, demonstrating excellent overall performance.

[0083] like Figure 3 and Figure 4 By comparing the neutron / photon shielding performance of tantalum-niobium coated boron carbide material with that of boron carbide shielding components, it can be demonstrated that the lightweight micro-reactor shielding material of tantalum-niobium coated boron carbide prepared in the embodiments of the present invention has superior neutron / photon shielding performance.

[0084] The above are merely preferred embodiments of the present invention and are 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 protection scope of the present invention.

Claims

1. A lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide coating, characterized in that, It is obtained by depositing a tantalum-niobium alloy coating on the surface of boron carbide particles as the core; the particle size of the boron carbide particles is 1μm to 10μm; and the thickness of the tantalum-niobium alloy coating is 0.5μm to 5μm.

2. The lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide as described in claim 1, characterized in that, In the tantalum-niobium alloy coating, the mass ratio of tantalum to niobium is 1 to 5:

1.

3. The lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide as described in claim 2, characterized in that, In the tantalum-niobium alloy coating, the mass ratio of tantalum to niobium is 1.5 to 2:

1.

4. The lightweight micro-reactor shielding material with tantalum-niobium coating and boron carbide as described in claim 1, characterized in that, The tantalum-niobium alloy coating is formed by reacting tantalum salt and niobium salt in a hydrogen atmosphere using chemical vapor deposition, and then co-depositing the resulting tantalum and niobium onto the surface of boron carbide particles to form a tantalum-niobium alloy coating on the surface of boron carbide particles.

5. A method for preparing a lightweight micro-miniature reactor shielding material with a tantalum-niobium coating as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Using boron carbide particles as the core, tantalum and niobium salts are reacted in a hydrogen atmosphere using chemical vapor deposition, and the resulting tantalum and niobium are co-deposited on the surface of boron carbide particles to form a tantalum-niobium alloy coating on the surface of boron carbide particles, thus obtaining a lightweight micro-scale reactor shielding material with tantalum-niobium coating boron carbide.

6. The method for preparing the lightweight micro-miniature reactor shielding material with tantalum-niobium coating and boron carbide coating according to claim 5, characterized in that, Tantalum salt is tantalum chloride; niobium salt is niobium chloride.

7. The method for preparing the lightweight micro-miniature reactor shielding material with tantalum-niobium coating and boron carbide coating according to claim 5, characterized in that, The flow rate of hydrogen is 150 mL / min to 300 mL / min.

8. A shielding component, characterized in that, The lightweight micro-scale reactor shielding material with tantalum-niobium coating and boron carbide as described in any one of claims 1 to 4 is formed by hot pressing or sintering, and then cured to obtain a shielding component.

9. A shielding component, characterized in that, The lightweight micro-miniature reactor shielding material with tantalum-niobium coating boron carbide as described in any one of claims 1 to 4 is mixed evenly with a matrix material and then formed by hot pressing or sintering to make the lightweight micro-miniature reactor shielding material with tantalum-niobium coating boron carbide uniformly dispersed in the matrix material. After curing, a shielding component is obtained; the matrix material is an aluminum alloy or a resin matrix.

10. The shielding member according to claim 8 or 9, characterized in that, The density of the shielding component is 2.5 g / cm³. 3 ~4.5g / cm 3 .

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