Ta / Al composite material for space radiation shielding and preparation method thereof

Abstract

The invention discloses a Ta / Al composite material for space radiation shielding and a preparation method of the Ta / Al composite material, and relates to the Ta / Al composite material for space radiation shielding and the preparation method of the Ta / Al composite material. The invention aims to solve the problem that reliable transition combination is difficult to realize due to thermal expansion coefficient difference between laminates in the traditional multi-layer shielding composite material. The Ta / Al composite material is composed of tantalum and an aluminum alloy, the aluminum alloy serves as a base body, tantalum serves as a reinforcement body, and the mass fraction of Ta in the Ta / Al composite material is 5-50%. The method comprises the following steps: 1, ball-milling mixed powder; 2, filling into a mold; 3, cold press molding of the mixed powder; 4, preserving heat in a protective atmosphere; 5, hot press molding in an atmospheric environment; and 6, waiting for cooling, and demolding to obtain the Ta / Al composite material. The Ta / Al composite material prepared by the invention has excellent mechanical and shielding properties. The invention is used in the field of space radiation shielding.

Description

Technical Field

[0001] This invention relates to a Ta / Al composite material for space radiation shielding and its preparation method. Background Technology

[0002] As human space exploration deepens, spacecraft ranges expand and on-orbit time extends, making the constraints of the space radiation environment on space missions increasingly prominent. The performance of radiation shielding materials has become a key factor determining the success or failure of space missions and ensuring the health and safety of astronauts. The space environment contains various high-energy radiation particles, including galactic cosmic rays, solar cosmic rays, and geomagnetic trapping radiation. These particles not only cause irreversible radiation damage to astronauts, inducing serious diseases such as hematopoietic system damage, genetic mutations, and even cancer, but also continuously bombard the spacecraft's electronic components, structural materials, and other core components, leading to component performance degradation and material aging failure, significantly shortening the spacecraft's on-orbit lifespan and posing a significant and continuous threat to its normal operation. Therefore, developing efficient and reliable space radiation shielding materials and constructing a stable radiation protection system has become a core and critical technology that urgently needs to be mastered in the overall design of spacecraft.

[0003] To improve space radiation shielding effectiveness, researchers are increasingly focusing their efforts on the composite design of high atomic number (high Z) metals and low atomic number (low Z) materials. High Z materials have a strong ability to block and scatter high-energy charged particles, effectively attenuating particle energy; low Z materials can efficiently absorb secondary radiation (such as bremsstrahlung) generated by the interaction of high-energy particles with matter. The synergistic effect of the two can achieve efficient shielding against various types of radiation. However, existing high Z / low Z composite shielding materials are mostly limited to multilayer composite plates or composite coating structures. This traditional composite structure has inherent drawbacks that are difficult to overcome: due to the significant differences in the coefficients of thermal expansion between different interlayer materials (such as high Z metal layers and low Z substrate layers, coatings and device shell substrates, etc.), large thermal stresses are easily generated between the layers during spacecraft launch and on-orbit operation when subjected to drastic temperature changes. This thermal stress can cause gaps, peeling, or even cracks at the interlayer bonding interface, making it impossible to achieve an organic transition and reliable bond between the layers. This not only severely weakens the overall structural stability and mechanical properties of the composite material, but also disrupts the continuity of radiation shielding, leading to a significant decrease in shielding effectiveness and even causing the protection system to fail.

[0004] Against this backdrop, integrated composite materials that combine structural load-bearing and radiation shielding functions have become an important research and development direction for radiation protection materials. Aluminum-based composite materials, with their excellent specific strength and specific stiffness, good corrosion resistance and heat resistance, as well as low density, can effectively reduce the launch cost of spacecraft, making them an ideal matrix choice for constructing integrated structural-functional radiation shielding materials. By uniformly introducing high-Z particles with excellent shielding functions into the aluminum matrix, the composite material can simultaneously possess lightweight structural characteristics and high-efficiency radiation shielding performance, perfectly meeting the core requirements of spacecraft for materials that are "lightweight, multifunctional, and highly reliable".

[0005] Among numerous high-Z metallic materials, tantalum (Ta) stands out as the preferred high-Z component for preparing high-Z / low-Z composite shielding materials due to its unique and superior properties. Tantalum boasts a high atomic number, resulting in exceptional attenuation capabilities for high-energy radiation particles. Furthermore, its extremely high melting point and excellent heat resistance allow it to withstand the extreme temperature variations of the space environment. In addition, tantalum exhibits high chemical stability, excellent corrosion resistance, and good ductility and toughness, making it easy to process and form, thus well-suited to the preparation and subsequent processing requirements of composite materials. Based on this, the preparation of Ta / Al composite materials by combining tantalum with aluminum is expected to fully leverage the high-efficiency radiation shielding advantages of tantalum and the lightweight structural advantages of aluminum, achieving an integrated function of "structural load-bearing and radiation shielding," providing a novel approach to solving the challenges of space radiation shielding.

[0006] Despite the significant application potential of Ta / Al composite materials, their large-scale preparation and engineering applications have long been hampered by technological bottlenecks in traditional material processing techniques. Previous preparations of Ta / Al composite metal materials have primarily employed multilayer composite processes involving alternating layers of aluminum sheets, tantalum sheets, or corresponding thin films. In these composites, the bonding between tantalum and aluminum remains at a simple interface bonding level, failing to achieve a uniform distribution of tantalum components within the aluminum matrix. This hinders the full realization of the synergistic shielding effect of tantalum and aluminum, and fails to maximize the material's multiple absorption advantages against electron radiation and bremsstrahlung. More importantly, this multilayered structure also suffers from mismatched interlayer thermal expansion coefficients, and the material exhibits extremely poor bonding performance with substrates commonly used in spacecraft, such as ceramic shells and metal covers for electronic packaging. Consequently, the theoretical shielding performance of Ta / Al composite materials cannot be effectively translated into practical engineering applications, severely restricting their widespread application in space radiation protection.

[0007] In summary, the challenge of reliable transition bonding due to differences in the thermal expansion coefficients between layers in traditional multilayer radiation shielding composite materials has become a core bottleneck restricting the development of space radiation protection technology. Developing a method to solve this interlayer bonding problem and achieve efficient composite material composition of tantalum and aluminum, thereby obtaining a structurally stable Ta / Al composite material with excellent shielding performance, is of vital practical significance and an urgent engineering need for overcoming the bottleneck in space radiation protection technology, ensuring the safe operation of spacecraft in orbit and the health of astronauts, and promoting the in-depth development of space exploration. Summary of the Invention

[0008] The present invention aims to solve the problem that the difference in thermal expansion coefficients between the layers in traditional multilayer shielding composite materials makes it difficult to achieve a reliable transition bond, and provides a Ta / Al composite material for space radiation shielding and its preparation method.

[0009] The present invention discloses a Ta / Al composite material for space radiation shielding, which is composed of tantalum and aluminum alloy, wherein the aluminum alloy is used as the matrix and tantalum is used as the reinforcement, and the mass fraction of Ta in the Ta / Al composite material is 5~50%.

[0010] The preparation method of the Ta / Al composite material for space radiation shielding according to the present invention is carried out in specific steps:

[0011] 1. Tantalum powder and aluminum alloy powder are mixed evenly using ball milling technology. The ball mill speed is 100~300 r / min, the ball milling time is 1~6 h, and the powder is sieved to obtain a uniform mixed powder.

[0012] 2. The mixed powder is filled into the mold and compacted by a vibrating table to obtain the blank to be cold-pressed;

[0013] 3. Hold the blank to be cold-pressed under a pressure of 50~200MPa for 3~10min to obtain the composite material preform;

[0014] 4. Place the composite preform along with the mold into a heat-preserving furnace, in an atmospheric environment or by introducing Ar protective gas, and heat it at a temperature of 400~700℃ for 2~6 hours to obtain the preheated composite preform.

[0015] 5. Remove the preheated composite material blank from the furnace and apply a hot pressing pressure of 100~500MPa within 15 minutes. Hold the pressure at this pressure for 5~30 minutes and then air cool it with the mold.

[0016] 6. After the mold and material have cooled to room temperature, pressure is applied to demold the material to obtain the Ta / Al composite material.

[0017] The beneficial effects of this invention are:

[0018] This invention addresses the problem of inconsistent thermal expansion coefficients among layers in traditional multilayer shielding composite materials, which hinders reliable transition bonding. A Ta / Al composite material for space radiation shielding is fabricated. Al and Ta are used as low and high atomic number materials, respectively, for composite shielding. The lower atomic number Al material moderates and shields the initial incident electrons with minimal bremsstrahlung generation, while Ta absorbs bremsstrahlung and moderates low-energy electrons. This achieves highly efficient shielding against high-energy electron radiation and its secondary radiation, which is of great significance for radiation protection design in spacecraft. Tantalum particles are uniformly dispersed in the aluminum matrix, forming a three-dimensional, continuous, and weak-point-free shielding network against incident particles, avoiding particle penetration channels that might occur in layered structures where the interfaces are parallel to the radiation direction. A strong interfacial bond is formed between the tantalum particles and the aluminum matrix through hot-pressing sintering. Simultaneously, the uniformly dispersed tantalum particles provide dispersion strengthening to the aluminum matrix, improving the material's strength while maintaining good toughness, achieving structural-functional integration. By changing the ratio of tantalum powder to aluminum powder, particle size, sintering process, etc., the density, shielding performance, thermal conductivity and mechanical properties of materials can be controlled within a wide range, achieving "gradient design" or "customization" of performance. Detailed Implementation

[0019] Specific Implementation Method 1: In this implementation method, a Ta / Al composite material for space radiation shielding is composed of tantalum and aluminum alloy, wherein the aluminum alloy serves as the matrix and tantalum serves as the reinforcement, and the mass fraction of Ta in the Ta / Al composite material is 5~50%.

[0020] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the tantalum is a micron-sized powder with a particle size of 1~20μm. Everything else is the same as in Specific Implementation Method One.

[0021] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the aluminum alloy is a micron-sized powder with a particle size of 5~100μm. Everything else is the same as in Specific Implementation Method One.

[0022] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method Three in that the aluminum alloy is a micron-sized powder with a particle size of 5~100μm. Everything else is the same as in Specific Implementation Method Three.

[0023] Specific Implementation Method 5: The preparation method of the Ta / Al composite material for space radiation shielding described in this implementation method is carried out according to the following steps:

[0024] 1. Tantalum powder and aluminum alloy powder are mixed evenly using ball milling technology. The ball mill speed is 100~300 r / min, the ball milling time is 1~6 h, and the powder is sieved to obtain a uniform mixed powder.

[0025] 2. The mixed powder is filled into the mold and compacted by a vibrating table to obtain the blank to be cold-pressed;

[0026] 3. Hold the blank to be cold-pressed under a pressure of 50~200MPa for 3~10min to obtain the composite material preform;

[0027] 4. Place the composite preform along with the mold into a heat-preserving furnace, in an atmospheric environment or by introducing Ar protective gas, and heat it at a temperature of 400~700℃ for 2~6 hours to obtain the preheated composite preform.

[0028] 5. Remove the preheated composite material blank from the furnace and apply a hot pressing pressure of 100~500MPa within 15 minutes. Hold the pressure at this pressure for 5~30 minutes and then air cool it with the mold.

[0029] 6. After the mold and material have cooled to room temperature, pressure is applied to demold the material to obtain the Ta / Al composite material.

[0030] This embodiment employs a "particle-reinforced composite structure" in which tantalum particles are uniformly dispersed in an aluminum matrix. The uniformly dispersed tantalum particles act as "microscopic constraint units," suppressing excessive thermal expansion of the aluminum matrix and reducing the overall thermal expansion and contraction of the material, thus reducing thermal stress generation at its source. In this particle-dispersed structure, thermal stress is distributed across numerous "tantalum particle-aluminum matrix" microscopic interfaces. Because the particle size is in the micrometer range (1~20μm), the stress application area at the microscopic interfaces is extremely small, and the stress direction is three-dimensionally randomly distributed, avoiding stress concentration between macroscopic layers. This allows thermal stress to be dissipated at the microscopic scale, preventing it from accumulating to the point of interface failure. The tantalum particles form a three-dimensional continuous shielding system within the aluminum matrix, eliminating macroscopic interfaces parallel to the radiation direction and completely eliminating the "penetration channels" of the layered structure, while ensuring the continuity and stability of the shielding performance.

[0031] In this embodiment, during the ball milling process, the surface oxide film of tantalum powder and aluminum powder is broken and removed under the impact and shearing action of the ball milling media, forming a fresh metal surface. At the same time, the powder particles undergo plastic deformation, cold welding, and refinement, so that the tantalum particles and aluminum particles form a pre-bonded state of "microscopic interlocking". During the preheating stage, the aluminum matrix is ​​in a semi-solid / solid state, and the surface atomic diffusion ability is enhanced. The interface contact between tantalum particles and aluminum matrix changes from "point contact" to "surface contact", and the interface gap is eliminated. During the hot pressing stage, under the high pressure, the interface atoms undergo significant diffusion and reaction, forming a continuous metallurgical bonding layer, which improves the interface shear strength. Its bonding energy is much higher than the physical adsorption energy, which can resist the thermal stress impact brought by temperature cycling and avoid interface peeling or cracking.

[0032] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the ball-to-material ratio in the ball milling and mixing technology described in step one is (2~10):1. Everything else is the same as in Specific Implementation Method Five.

[0033] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Five in that, in step three, the blank to be cold-pressed is held under pressure of 50~150MPa for 3~10 minutes. Everything else is the same as in Specific Implementation Method Five.

[0034] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Five in that, in step three, the blank to be cold-pressed is held under pressure of 100~200MPa for 3~10 minutes. Everything else is the same as in Specific Implementation Method Five.

[0035] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Five in that the pressure demolding described in step six involves holding the pressure at 150~250MPa for 5~10 minutes before direct demolding. Everything else is the same as in Specific Implementation Method Five.

[0036] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Five in that the mass fraction of Ta in the Ta / Al composite material described in step six is ​​5-50%. Everything else is the same as in Specific Implementation Method Five.

[0037] The beneficial effects of the present invention are verified using the following embodiments:

[0038] Example 1: A method for preparing the Ta / Al composite material for space radiation shielding is specifically carried out according to the following steps:

[0039] 1. Tantalum powder and 6061Al powder are mixed evenly using ball milling technology. The ball mill speed is 100~200 r / min and the ball milling time is 6h. The powder is then sieved to obtain a uniform mixed powder. The ball-to-powder ratio is (2~10):1.

[0040] 2. The mixed powder is filled into a graphite mold and compacted by a vibrating table to obtain a blank to be cold-pressed;

[0041] 3. Hold the blank to be cold-pressed under a pressure of 100~200MPa for 3~10min to obtain the composite material preform;

[0042] 4. Place the composite preform along with the mold into a heat-preserving furnace, introduce Ar protective gas, and heat at 500~700℃ for 2~4 hours to obtain the preheated composite preform.

[0043] 5. Remove the preheated composite material blank from the furnace and apply a hot pressing pressure of 100~200MPa within 15 minutes. Hold the pressure at this pressure for 10~20 minutes and then air cool it with the mold.

[0044] 6. After the mold and material have cooled to room temperature, they are held under pressure of 150-250 MPa for 5-10 minutes and then directly demolded to obtain the Ta / Al composite material; the mass fraction of Ta in the Ta / Al composite material is 40%.

[0045] The density of the 40 wt.% Ta / Al composite sheet obtained from Example 1 is 4.093 g / cm³. 2 It has a tensile strength of 300 MPa, an elongation of 14.6%, a thermal conductivity of 140 W / (m·K), and a coefficient of thermal expansion of 22.5 × 10⁻⁶. -6 / K (30-100℃). Table 1 shows the performance test results of the Ta / Al composite shielding material thin plate obtained in Example 1.

[0046] Table 1

[0047]

Claims

1. A Ta / Al composite material for space radiation shielding, characterized in that... The Ta / Al composite material used for space radiation shielding is composed of tantalum and aluminum alloy, wherein the aluminum alloy serves as the matrix and tantalum serves as the reinforcement, and the mass fraction of Ta in the Ta / Al composite material is 5~50%.

2. The Ta / Al composite material for space radiation shielding according to claim 1, characterized in that... The tantalum is a micron-sized powder with a particle size of 1~20μm.

3. The Ta / Al composite material for space radiation shielding according to claim 1, characterized in that... The aluminum alloy is a micron-sized powder with a particle size of 5~100μm.

4. The aluminum alloy powder according to claim 3, characterized in that... The aluminum alloy is a 1xxx series aluminum alloy, a 2xxx series aluminum alloy, a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy.

5. The method for preparing a Ta / Al composite material for space radiation shielding as described in claim 1, characterized in that... The preparation method of the Ta / Al composite material for space radiation shielding is specifically carried out according to the following steps:

1. Tantalum powder and aluminum alloy powder are mixed evenly using ball milling technology. The ball mill speed is 100~300 r / min, the ball milling time is 1~6 h, and the powder is sieved to obtain a uniform mixed powder.

2. The mixed powder is filled into the mold and compacted by a vibrating table to obtain the blank to be cold-pressed; 3. Hold the blank to be cold-pressed under a pressure of 50~200MPa for 3~10min to obtain the composite material preform; 4. Place the composite preform along with the mold into a heat-preserving furnace, in an atmospheric environment or by introducing Ar protective gas, and heat it at a temperature of 400~700℃ for 2~6 hours to obtain the preheated composite preform.

5. Remove the preheated composite material blank from the furnace and apply a hot pressing pressure of 100~500MPa within 15 minutes. Hold the pressure at this pressure for 5~30 minutes and then air cool it with the mold.

6. After the mold and material have cooled to room temperature, pressure is applied to demold the material to obtain the Ta / Al composite material.

6. A method for preparing a Ta / Al composite material for space radiation shielding according to claim 5, characterized in that... The ball-to-material ratio in the ball milling and mixing technology described in step one is (2~10):

1.

7. A method for preparing a Ta / Al composite material for space radiation shielding according to claim 5, characterized in that... In step three, the blank to be cold-pressed is held under pressure of 50~150MPa for 3~10 minutes.

8. A method for preparing a Ta / Al composite material for space radiation shielding according to claim 5, characterized in that... In step three, the blank to be cold-pressed is held under pressure of 100~200MPa for 3~10 minutes.

9. A method for preparing a Ta / Al composite material for space radiation shielding according to claim 5, characterized in that... The pressure demolding described in step six involves holding the pressure at 150-250 MPa for 5-10 minutes before directly demolding.

10. A method for preparing a Ta / Al composite material for space radiation shielding according to claim 5, characterized in that... The mass fraction of Ta in the Ta / Al composite material described in step six is ​​5-50%.

Images