Neutron gamma composite shielding material and preparation method thereof

Abstract

The application discloses a neutron gamma composite shielding material and a preparation method thereof. The neutron gamma composite shielding material takes micron plate structure samarium oxide as a neutron and gamma ray absorber, boron carbide as a neutron absorber, and high-density polyethylene as a base material. The micron plate structure samarium oxide filler has a high specific surface area, can increase the probability of interaction with neutron gamma rays, and improve the neutron gamma shielding capacity of the composite material. In addition, high-energy ball milling, dense mixing and other preparation processes are used to reduce the clustering of inorganic fillers in the matrix and improve the interfacial compatibility between the inorganic fillers and the polymer matrix. The neutron gamma composite shielding material disclosed by the application contains micron plate structure samarium oxide, has high thermal stability and mechanical properties, and excellent radiation shielding performance, and can be used in the field of high-performance neutron gamma radiation shielding under a medium and low temperature environment, such as nuclear facility radiation protection, nuclear waste disposal, radiation protection for radiotherapy, and the like.

Description

Technical Field

[0001] This invention belongs to the field of radiation protection technology, specifically relating to a neutron-gamma composite shielding material and its preparation method. Background Technology

[0002] With the development of aerospace, radiation medicine, and civilian nuclear power, higher requirements have been placed on nuclear radiation shielding. Nuclear reactions produce various particles and radiation rays, such as alpha particles, beta particles, neutrons of different energies, gamma rays, and other charged particles and high-energy rays. Because the high-energy neutrons and gamma rays produced in nuclear reactions are highly energetic, they can penetrate the human body, causing various health problems such as nerve damage, reproductive damage, heart disease, leukemia, and cancer. Therefore, the research and development of neutron and gamma radiation shielding materials is particularly necessary.

[0003] Light-nuclear elements (such as hydrogen, carbon, and oxygen) have low atomic numbers and readily undergo elastic collisions with neutrons, rapidly reducing the neutron's energy. Polyethylene, a typical hydrogen-rich material, is widely used in radiation shielding due to its lightweight, ease of processing, and strong neutron attenuation capabilities. Boron carbide materials have a high thermal neutron absorption cross-section, and the secondary gamma rays produced by thermal neutron capture reactions are relatively weak, making them widely used as neutron absorbers. Materials with high atomic numbers and high density exhibit good gamma-ray shielding effects. Rare earth oxides (such as Gd₂O₃, Sm₂O₃, etc.) have the characteristics of high thermal neutron absorption cross section, high atomic number, and environmental friendliness, and can be used as fillers for neutron-gamma composite shielding materials. For example, gadolinium has a high thermal neutron absorption cross section and high atomic number, but gadolinium usually produces high-energy secondary gamma rays when interacting with thermal neutrons, which limits its use in neutron-gamma composite radiation fields. Compared with gadolinium, samarium not only has the advantages of high thermal neutron absorption cross section, high atomic number, and low cost, but also produces secondary gamma rays with weaker energy when interacting with thermal neutrons, making it more suitable for neutron-gamma composite radiation fields.

[0004] Current research on neutron-gamma radiation shielding materials focuses on optimizing the types and proportions of fillers, with less attention paid to the microstructure and size of the fillers. Some studies have shown that functional fillers with high specific surface area (such as Bi₂WO₆, CdO, and PbO) can increase the probability of interaction between the filler and radiation particles, positively impacting the shielding performance of composite shielding materials. However, the fillers used in these studies are commercial reagents, and their microstructure, particle size, and specific surface area are uncontrollable. Furthermore, there are few reports on the relationship between the microstructure of rare-earth-based fillers and the radiation shielding performance, thermal stability, and mechanical properties of composite shielding materials. Therefore, it is essential to synthesize rare-earth-based fillers with specific morphologies and high specific surface areas, especially micro / nano-structured Sm₂O₃ fillers, for the development of neutron-gamma composite shielding materials. Summary of the Invention

[0005] To address the shortcomings and deficiencies of polymer-based composite shielding materials, this invention aims to provide a neutron-gamma composite shielding material and its preparation method. The neutron-gamma composite shielding material is a neutron-gamma composite shielding material containing micron-sized plate-structured samarium oxide filler. This neutron-gamma composite shielding material incorporates two fillers: high specific surface area micron-sized plate-structured Sm2O3 and B4C. The introduction of the high specific surface area micron-sized plate-structured Sm2O3 filler increases the probability of interaction between the shielding material and neutrons and gamma rays, improving the neutron-gamma shielding capability of the composite shielding material. Furthermore, the neutron absorption energy ranges of Sm2O3 and B4C are complementary. In addition, to solve the interfacial compatibility problem between the polymer and the inorganic filler, this invention uses a series of processes such as high-energy ball milling and intensive mixing to reduce the clustering problem of inorganic fillers in the matrix, improve the interfacial compatibility between the inorganic filler and the polymer matrix, and enhance the mechanical and heat resistance properties of the composite material.

[0006] This invention is achieved through the following technical solution:

[0007] A neutron-gamma composite shielding material uses samarium oxide with a micron-plate structure as a neutron and gamma ray absorber, boron carbide as a neutron absorber, and high-density polyethylene as a matrix material. The mass content of each component in the neutron-gamma composite shielding material, based on the total mass of the material, is as follows:

[0008] High-density polyethylene: 40–90 wt%;

[0009] Boron carbide: 5–40 wt%;

[0010] Samarium oxide in micron-plate structure: 4–50 wt%.

[0011] For example, based on the total mass of the neutron-gamma composite shielding material, the mass content of each component of the neutron-gamma composite shielding material is as follows:

[0012] High-density polyethylene: 40wt%, 42wt%, 45wt%, 47wt%, 50wt%, 52wt%, 55wt%, 57wt%, 60wt%, 62wt%, 65wt%, 67wt%, 70wt%, 72wt%, 75wt%, 77wt%, 80wt%, 82wt%, 85wt%, 87wt%, or 90wt%;

[0013] Boron carbide: 5wt%, 7wt%, 10wt%, 12wt%, 15wt%, 17wt%, 20wt%, 22wt%, 25wt%, 27wt%, 30wt%, 32wt%, 35wt%, 37wt% or 40wt%;

[0014] Samarium oxide in micron-sized plate structures: 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt%, 20wt%, 22wt%, 25wt%, 27wt%, 30wt%, 32wt%, 35wt%, 37wt%, 40wt%, 42wt%, 45wt%, 47wt%, or 50wt%.

[0015] Furthermore, the samarium oxide with the micron-plate structure has a particle size of 0.1-10 μm and a specific surface area of ​​1-100 m². 2 / g, pore volume 0.01~0.5cm³ 3 / g, with an average pore diameter of 1–100 nm. For example, the particle sizes of the micron-plate structured samarium oxide are 0.1 μm, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4 0.8μm, 5μm, 5.2μm, 5.4μm, 5.6μm, 5.8μm, 6μm, 6.2μm, 6.4μm, 6.6μm, 6.8μm, 7μm, 7.2μm, 7.4μm, 7.6μm, 7.8μm, 8μm, 8.2μm, 8.4μm, 8.6μm, 8.8μm, 9μm, 9.2μm, 9.4μm, 9.6μm, 9.8μm or 10μm, with a specific surface area of ​​1m³. 2 / g、5m 2 / g, 10m 2 / g, 15m 2 / g、20m 2 / g、25m 2 / g、30m 2 / g、35m 2 / g、40m 2 / g、45m 2 / g, 50m 2 / g、55m 2 / g、60m 2 / g、65m 2 / g、70m 2 / g、75m 2 / g、80m 2 / g、85m 2 / g、90m 2 / g、95m 2 / g or 100m 2 / g, pore volume is 0.01cm³ 3 / g, 0.03cm 3 / g, 0.05cm 3 / g, 0.07cm 3 / g, 0.09cm 3 / g, 0.11cm 3 / g, 0.13cm 3 / g, 0.15cm 3 / g, 0.17cm 3 / g, 0.19cm 3 / g, 0.21cm 3 / g, 0.23cm 3 / g, 0.25cm 3 / g, 0.27cm 3 / g, 0.29cm 3 / g, 0.31cm 3 / g, 0.33cm 3 / g, 0.35cm 3 / g, 0.37cm 3 / g, 0.39cm 3 / g, 0.41cm 3 / g, 0.43cm 3 / g, 0.45cm 3 / g, 0.47cm 3 / g, 0.49cm 3 / g or 0.5cm 3 / g, with average pore diameters of 1nm, 3nm, 5nm, 7nm, 9nm, 11nm, 13nm, 15nm, 17nm, 19nm, 21nm, 23nm, 25nm, 27nm, 29nm, 31nm, 33nm, 35nm, 37nm, 39nm, 41nm, 43nm, 45nm, 47nm, 49nm, 51nm, 53nm, 55nm, 57nm, 59nm, 61nm, 63nm, 65nm, 67nm, 69nm, 71nm, 73nm, 75nm, 77nm, 79nm, 81nm, 83nm, 85nm, 87nm, 89nm, 91nm, 93nm, 95nm, 97nm, 99nm, or 100nm.

[0016] A method for preparing a neutron-gamma composite shielding material as described above includes the following steps:

[0017] Micron-sized samarium oxide, boron carbide, and high-density polyethylene were ball-milled and mixed for 1–60 min to ensure uniform mixing. The mixed powder was then placed in an internal mixer and mixed at 140–240°C for 1–60 min. The resulting product was then crushed in a crusher. The crushed particles were placed in a hot press mold and hot-pressed under the following conditions: first, holding at 140–400°C with a pressure of 0–20 MPa for 1–30 min; then holding at 180–400°C with a pressure of 5–90 MPa for 10–100 min; finally, holding at 190–400°C with a pressure of 20–90 MPa for 10–200 min. The mixture was then cooled and demolded to obtain the neutron-gamma shielding composite material.

[0018] Furthermore, a method for preparing a neutron-gamma composite shielding material as described above includes the following steps:

[0019] The micron-sized samarium oxide, boron carbide, and high-density polyethylene were ball-milled for 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min to ensure uniform mixing. The mixed powder was then placed in an internal mixer and kneaded at 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, or 240℃ for 1 min, 5 min, 10 min, 15 min, 20 min, or 25 min. After 30, 35, 40, 45, 50, 55, or 60 minutes, the product from the intensive mixing process is placed into a crusher for crushing. The crushed particles are then placed into a hot press mold and hot-pressed under the following conditions: 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 33℃, 340℃, 350℃, 360℃, and 370℃. The temperature and pressure are maintained at 380℃, 390℃, or 400℃, and the pressure applied to the hot press mold by the hot press is 0MPa, 5MPa, 10MPa, 15MPa, or 20MPa for 1–30 minutes; subsequently, the temperature and pressure are maintained at 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 33℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, or 400℃, and the pressure applied to the hot press mold by the hot press is 5MPa, 10MPa, 1… Hold at 5MPa, 20MPa, 25MPa, 30MPa, 35MPa, 40MPa, 45MPa, 50MPa, 55MPa, 60MPa, 65MPa, 70MPa, 75MPa, 80MPa, 85MPa or 90MPa for 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, 65min, 70min, 75min, 80min, 85min, 90min, 95min or 100min.Finally, at temperatures of 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 33℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, or 400℃, the pressure applied by the hot press to the hot press mold is 20MPa, 25MPa, 30MPa, 35MPa, 40MPa, 45MPa, 50MPa, 55MPa, 60MPa, or 65MPa. a. The material is held at 70 MPa, 75 MPa, 80 MPa, 85 MPa, or 90 MPa for 0 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 150 min, or 200 min; then cooled and demolded to obtain the neutron-gamma shielding composite material.

[0020] Furthermore, the micron-plate structured samarium oxide (Sm2O3) is prepared by the following method:

[0021] (1) Weigh samarium nitrate and urea. The molar ratio of samarium nitrate to urea is 0.01 to 10. For example, the molar ratio of samarium nitrate to urea is 0.01, 0.03, 0.05, 0.07, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.3, 1.5, 1.7, 1.9, 2, 2.1, 2.3, 2.5, 2.7, 2.9, 3, 3.1, 3.3, 3.5, 3.7, 3.9, 4, 4.1, 4.3, 4.5, 4.7, 4.9, 5, 5.1, 5.3, 5.5, 5.7, 5.9, 6, 6.1, 6.3, 6.5, 6.7, 6.9, 7, 7.1, 7.3, 7.5, 7.7, 7.9, 8, 8.5, 9, 9.5, or 10;

[0022] (2) Dissolve samarium nitrate and urea in ultrapure water and stir at room temperature for 1 to 120 minutes to make the solution uniform. Then, keep the mixed solution at 60 to 140°C for 0.1 to 8 hours to obtain an emulsion. For example, keep the mixed solution at 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C or 140°C for 0.1 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0023] (3) Centrifuge the emulsion to obtain a precipitate, and wash the precipitate;

[0024] For example, the precipitate is washed by alternating the addition of ultrapure water and ethanol to the precipitate obtained by centrifugation three to ten times until the supernatant is clear and transparent.

[0025] (4) The cleaned precipitate is placed in an oven and dried at a constant temperature of 30–120°C for 0.1–24 h, and then transferred to a heating furnace and sintered at a constant temperature of 300°C–1900°C for 0.1–12 h to obtain the micron-plate structured samarium oxide. For example, the cleaned precipitate is placed in an oven and dried at a constant temperature of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or 120°C for 0.1 h, 5 h, 10 h, 15 h, 20 h, or 24 h, and then transferred to a heating furnace and sintered at a constant temperature of 300°C, 350°C, 400°C, or 190 ... respectively. The samarium oxide micron plate structure was obtained by isothermal sintering at 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, 1600℃, 1700℃, 1800℃ or 1900℃ for 0.1h, 5h, 10h or 12h.

[0026] Furthermore, the screen aperture of the crusher is 0.5 to 50 mm. For example, the screen aperture of the crusher is 0.5 mm, 1 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm or 50 mm.

[0027] This neutron-gamma composite shielding material is suitable for high-performance neutron-gamma radiation shielding in medium and low temperature (not exceeding 100℃) or normal temperature environments, such as radiation protection for nuclear facilities, radiation protection for radioactive source libraries, nuclear waste preparation, and radiation protection for radiomedical treatment.

[0028] The advantages of this invention are:

[0029] This neutron-gamma composite shielding material incorporates two fillers: Sm₂O₃ and B₄C, both with high specific surface area micron-plate structures. The introduction of Sm₂O₃ increases the probability of its interaction with neutrons and gamma rays, thus enhancing the neutron-gamma shielding capability of the composite material. Furthermore, the neutron absorption energy ranges of Sm₂O₃ and B₄C are complementary. In addition, a series of processes, including high-energy ball milling and high-temperature mixing, improve the dispersibility of the functional fillers in the matrix, enhance the interfacial compatibility between the functional fillers and the matrix material, and improve the mechanical and heat resistance properties of the neutron-gamma composite shielding material. Attached Figure Description

[0030] Figure 1 SEM images of samarium oxide filler with micron-sized plate structure: (a) samarium oxide filler with micron-sized plate structure (R=1:10), (b) samarium oxide filler with micron-sized plate structure (R=1:20), (c) samarium oxide filler with micron-sized plate structure (R=1:25), (d) samarium oxide filler with micron-sized plate structure (R=1:30);

[0031] Figure 2 XRD pattern of samarium oxide filler with micron-sized plate structure;

[0032] Figure 3 Schematic diagram of neutron and gamma shielding performance testing device, (a) schematic diagram of neutron shielding performance testing device, (b) schematic diagram of gamma shielding performance testing device;

[0033] Figure 4 N2 adsorption-desorption isotherms and pore size distribution of samarium oxide packing with micron-sized plate structure. Detailed Implementation

[0034] The scope of protection of this invention should include all the contents of the claims; the invention will be described in detail below through specific embodiments. The embodiments are only for explaining the invention. In order to make the purpose, technical solution and advantages of the invention clearer, the invention will be explained and described in conjunction with the accompanying drawings and specific embodiments; through the detailed description of the drawings and embodiments, those skilled in the art can fully grasp all the contents of the invention claims.

[0035] In the following embodiments of the present invention, the R value represents the Sm value of the reactants in the synthesis reaction of micron-plate structure Sm2O3. 3+ The molar ratio of reactants between ions and urea molecules.

[0036] In the following embodiments of the present invention, some of the raw materials and testing methods used are as follows:

[0037] High-density polyethylene powder (China Petroleum & Chemical Corporation Maoming Branch, product model HHW5502LW, density 0.96 g / cm³) 3 );

[0038] Material characterization test instructions:

[0039] SEM image (field emission scanning electron microscope, Carl Zeiss Group, Germany, model ΣIGMA);

[0040] XRD pattern (X-ray diffractometer, Rigaku Electric Co., Ltd., Japan, model TTR-III);

[0041] BET specific surface area (m²) 2 / g), pore volume (cm³) 3 The data for surface area ( / g) and average pore diameter (nm) were obtained using a specific surface area and porosity analyzer (McMerritt Instruments, Inc., Tristar II 3020). The specific procedure was as follows: the material was placed in an N2 environment, and the N2 isotherm adsorption-desorption curves were obtained by varying the relative pressure of N2. The specific surface area was calculated using the Brunauer-Emmett-Teller (BET) model, and the average pore diameter and pore volume were calculated using the Barret-Joyner-Halenda (BJH) model.

[0042] The neutron shielding performance testing device consists of a polyethylene collimated shielding cylinder, a Cf-252 neutron source, and a high-sensitivity neutron detector, arranged as follows: Figure 3 As shown in (a), the polyethylene collimating shield is 150cm long and 50cm thick. It has a 4cm diameter through-hole in the center, and a high-sensitivity neutron detector is located 20cm directly opposite the exit port. The specific procedure for neutron shielding testing is as follows: First, a high-sensitivity neutron detector (Fluke Test Instruments, Inc., Model SmartREM) is used to detect the neutron count in the environment without a Cf-252 neutron source and the shielding material under test. This count is marked as I. n0b Subsequently, the shielding material to be tested was placed tightly against the exit hole of the polyethylene collimating shielding cylinder, and the neutron count displayed by the neutron detector was recorded when the Cf-252 neutron source was not loaded and the shielding material to be tested was loaded. This count was marked as I. nb Then, remove the shielding material at the exit port of the polyethylene collimating shield and place the Cf-252 neutron source inside the polyethylene collimating shield at the designated position (30cm from the exit port). Use a high-sensitivity neutron detector to detect the neutron count in the current state and mark it as I. n0 Then, a shielding material was placed close to the exit hole of the polyethylene collimating shielding cylinder, and the neutron count displayed by the neutron detector was recorded when the Cf-252 neutron source and the shielding material to be tested were loaded, and marked as I. n Each test was repeated 10 times, and the average value was taken.

[0043] Neutron shielding efficiency S nThe calculation formula is:

[0044] The gamma-ray shielding performance testing device consists of a lead collimated shielding cylinder, a Cs-137 gamma source, and a portable radiation detector, arranged as follows: Figure 3 As shown in (b), the length of the lead collimation shield is 50cm, the wall thickness is 15cm, and there is a 1cm diameter through hole in the middle of the lead collimation shield. The portable radiation detector is located 20cm directly opposite the exit port of the lead collimation shield. The specific procedure for gamma ray shielding testing is as follows: First, a portable radiation detector (Thermo Fisher Scientific, model FHZ672 E-10) is used to detect the gamma count in the environment without a Cs-137 gamma source and the shielding material under test, marked as I. γ0b Subsequently, the shielding material was placed tightly against the exit hole of the lead collimating shielding cylinder, and the gamma count displayed by the portable radiation detector was recorded when the Cs-137 gamma source was not loaded and the shielding material to be tested was loaded. This count was marked as I. γb Then, remove the shielding material at the exit port of the lead collimation shield and place the Cs-137 gamma source inside the lead collimation shield at the designated position (20cm from the exit port). Use a portable radiation detector to detect the gamma count under the current condition and mark it as I. γ0 Then, place the shielding material close to the exit hole of the lead collimation shielding cylinder, and record the gamma count displayed by the portable radiation detector when placing the Cs-137 gamma source and the shielding material to be tested, marked as I. γ Each test was repeated 10 times, and the average value was taken.

[0045] Gamma shielding rate S γ The calculation formula is:

[0046] Example 1

[0047] Weigh 0.01 mol of samarium nitrate hexahydrate powder and 0.1 mol of urea powder using an electronic analytical balance and place them in an Erlenmeyer flask. Add 800 ml of ultrapure water to the flask and stir at room temperature for 30 min to completely dissolve and mix the powder. Then, transfer the Erlenmeyer flask containing the reaction solution to an oil bath, maintaining the temperature of the reaction solution at 85°C for 3 h. After the reaction is complete, transfer the solution from the Erlenmeyer flask to a centrifuge tube and centrifuge at 8000 rpm for approximately 4 min. After centrifugation, discard the supernatant in the centrifuge tube, add ultrapure water to the centrifuge tube, and continue centrifuging. Repeat this operation 5 times until the supernatant is clear. Subsequently, add ethanol to the centrifuge tube and continue centrifuging. After each centrifugation, discard the supernatant in the centrifuge tube, add ethanol to the centrifuge tube, and continue centrifuging. Repeat this process 5 times until the supernatant is clear, indicating that the impurities in the precipitate in the centrifuge tube have been completely removed. The precipitate in the centrifuge tube was then placed in an oven and dried at 60°C for 6 hours. Finally, the dried precipitate was placed in a tube furnace and sintered at 800°C for 2 hours to obtain Sm2O3 with a micron plate structure, which was labeled as micron plate Sm2O3 (R = 1:10).

[0048] SEM images, XRD patterns, N2 adsorption-desorption isotherms and pore size distribution diagrams, and BET specific surface area parameters of micron-sized Sm2O3 (R=1:10) are shown below. Figure 1 (a), Figure 2 , Figure 4 As shown in Table 1, the XRD pattern indicates that the micron-plate Sm2O3 (R = 1:10) belongs to the cubic crystal system with space group Ia-3(206); the SEM image and BET test show that Sm2O3 has a micron-plate morphology with gaps and the size of the micron-plate is about 2 μm.

[0049] The hysteresis loop on the nitrogen adsorption-desorption curve in BET is of type H3, indicating that the prepared Sm2O3 is a plate-like slit material with a BET specific surface area, pore volume, and average pore diameter of 3.76 m² / s. 2 / g, 0.032cm 3 / g, 32.92nm.

[0050] 36g of Sm2O3 (R=1:10) powder, 72g of B4C powder, and 252g of high-density polyethylene powder were weighed separately. The three powders were then ball-milled at 900 rpm for 10 minutes. The mixture was then placed in a mixer and kneaded at 210℃ for 20 minutes. The kneaded product was then crushed in a crusher with a 3mm screen for 60 minutes. The crushed particles were placed in a hot press mold with release paper, and hot-pressed under the following conditions: first, pre-pressing at 220℃ and 0 MPa (pressure applied by the hot press to the mold) for 10 minutes; then holding at 220℃ and 30 MPa for 30 minutes; and finally holding at 240℃ and 55 MPa for 90 minutes. After cooling to room temperature, the pressure was released and the mold was demolded to obtain micron-sized Sm2O3 (R=1:10) plates.

[0051] 1:10) / B4C / HDPE neutron gamma shielding composite material.

[0052] The heat resistance and mechanical properties of the composite material prepared in this embodiment are shown in Tables 2 and 3.

[0053] The neutron shielding performance testing device consists of a polyethylene collimated shielding cylinder, a Cf-252 neutron source, and a high-sensitivity neutron detector. When the material thickness is 1.5 cm, the neutron shielding efficiency is 45.8%. The gamma-ray shielding performance testing device consists of a lead collimated shielding cylinder, a Cs-137 gamma source, and a portable radiation detector. When the material thickness is 1.5 cm, the gamma-ray shielding efficiency is 13.3%.

[0054] Example 2

[0055] Weigh 0.01 mol of samarium nitrate hexahydrate powder and 0.2 mol of urea powder using an electronic analytical balance and place them in an Erlenmeyer flask. Add 800 ml of ultrapure water to the flask and stir at room temperature for 30 min to completely dissolve and mix the powder. Then, transfer the Erlenmeyer flask containing the reaction solution to an oil bath, maintain the temperature of the reaction solution at 85°C, and react for 3 h. After the reaction is complete, transfer the solution from the Erlenmeyer flask to a centrifuge tube and centrifuge at 8000 rpm for about 4 min. After centrifugation, discard the supernatant in the centrifuge tube, add ultrapure water to the centrifuge tube, and continue centrifuging. Repeat the above operation 5 times until the supernatant is clear. Then, add ethanol to the centrifuge tube and continue centrifugation. After each centrifugation, discard the supernatant in the centrifuge tube, add ethanol to the centrifuge tube, and continue centrifugation. Repeat the above process 5 times until the supernatant is clear, indicating that the impurities in the precipitate in the centrifuge tube have been completely removed. The precipitate in the centrifuge tube was then placed in an oven and dried at 60°C for 6 hours. Finally, the dried precipitate was placed in a tube furnace and sintered at 800°C for 2 hours to obtain micron-plate structured Sm2O3, labeled as micron-plate Sm2O3 (R = 1:20).

[0056] SEM images, XRD patterns, N2 adsorption-desorption isotherms and pore size distribution diagrams, and BET specific surface area parameters of micron-sized Sm2O3 (R=1:20) are shown below. Figure 1 (b), Figure 2 , Figure 4 As shown in Table 1, the XRD pattern indicates that the micron-sized Sm₂O₃ (R = 1:20) belongs to the cubic crystal system with space group Ia⁻³(206). SEM images and BET measurements show that Sm₂O₃ exhibits a micron-sized plate morphology with gaps, and the plate size is approximately 2.2 μm. The hysteresis loop on the nitrogen adsorption-desorption curve in the BET test is of the H₃ type, indicating that the prepared Sm₂O₃ is a plate-like material with gaps. Its BET specific surface area, pore volume, and average pore diameter are 7.57 m² / s². 2 / g, 0.043cm 3 / g, 20.54nm.

[0057] Weigh 36g of Sm2O3 (R=1:20) powder and 72g of... B4C powder and 252g of high-density polyethylene powder were mixed in a high-energy ball mill at 900rpm / min for 10min. The mixed powder was then mixed and kneaded in an internal mixer at 210℃ for 20min. The kneaded product was then crushed in a crusher with a 3mm screen size for 60min. The crushed particles were placed in a hot press mold with release paper and hot-pressed under the following conditions: first, pre-pressing at 220℃ and 0MPa (pressure applied by the hot press to the mold) for 10min; then holding at 220℃ and 30MPa for 30min; and finally holding at 240℃ and 55MPa for 90min. After cooling to room temperature and depressurizing, a micron-sized Sm2O3 (R=1:20) / B4C / HDPE neutron gamma shielding composite material was obtained.

[0058] The heat resistance and mechanical properties of the composite material prepared in this embodiment are shown in Tables 2 and 3.

[0059] The neutron shielding performance testing device consists of a polyethylene collimated shielding cylinder, a Cf-252 neutron source, and a high-sensitivity neutron detector. When the material thickness is 1.5 cm, the neutron shielding efficiency is 47.4%. The gamma-ray shielding performance testing device consists of a lead collimated shielding cylinder, a Cs-137 gamma source, and a portable radiation detector. When the material thickness is 1.5 cm, the gamma-ray shielding efficiency is 13.9%.

[0060] Example 3

[0061] Weigh 0.01 mol of samarium nitrate hexahydrate powder and 0.25 mol of urea powder using an electronic analytical balance and place them in an Erlenmeyer flask. Add 800 ml of ultrapure water to the flask and stir at room temperature for 30 min to completely dissolve and mix the powder. Then, transfer the Erlenmeyer flask containing the reaction solution to an oil bath, maintain the temperature of the reaction solution at 85°C, and react for 3 h. After the reaction is complete, transfer the solution from the Erlenmeyer flask to a centrifuge tube and centrifuge at 8000 rpm for about 4 min. After centrifugation, discard the supernatant in the centrifuge tube, add ultrapure water to the centrifuge tube, and continue centrifuging. Repeat the above operation 5 times until the supernatant is clear. Then, add ethanol to the centrifuge tube and continue centrifugation. After each centrifugation, discard the supernatant in the centrifuge tube, add ethanol to the centrifuge tube, and continue centrifugation. Repeat the above process 5 times until the supernatant is clear, indicating that the impurities in the precipitate in the centrifuge tube have been completely removed. The precipitate in the centrifuge tube was then placed in an oven and dried at 60°C for 6 hours. Finally, the dried precipitate was placed in a tube furnace and sintered at 800°C for 2 hours to obtain micron-plate structured Sm2O3, labeled as micron-plate Sm2O3 (R = 1:25).

[0062] SEM images, XRD patterns, N2 adsorption-desorption isotherms and pore size distribution diagrams, and BET specific surface area parameters of micron-sized Sm2O3 (R=1:25) are shown below. Figure 1 (c), Figure 2 , Figure 4 As shown in Table 1, XRD patterns indicate that the micron-sized Sm₂O₃ (R = 1:25) belongs to the cubic crystal system with space group Ia⁻³(206). SEM images and BET tests show that Sm₂O₃ exhibits a micron-sized plate morphology with gaps, and the plate size is approximately 2.4 μm. The hysteresis loop on the nitrogen adsorption-desorption curve in BET is of type H₃, indicating that the prepared Sm₂O₃ is a plate-like material with gaps. Its BET specific surface area, pore volume, and average pore diameter are 8.20 m², respectively. 2 / g, 0.045cm 3 / g, 20.09nm.

[0063] Weigh 36g of Sm2O3 (R=1:25) powder and 72g of... B4C powder and 252g of high-density polyethylene powder were mixed in a high-energy ball mill at 900rpm / min for 10min. The mixture was then mixed in an internal mixer at 210℃ for 20min. The resulting product was crushed in a crusher with a 3mm screen for 60min. The crushed particles were placed in a hot press mold with release paper and hot-pressed under the following conditions: first, pre-pressing at 220℃ and 0MPa (pressure applied by the hot press to the mold) for 10min; then holding at 220℃ and 30MPa for 30min; and finally holding at 240℃ and 55MPa for 90min. After cooling to room temperature and depressurizing, a micron-sized Sm2O3 (R=1:25) / B4C / HDPE neutron-gamma shielding composite material was obtained.

[0064] The heat resistance and mechanical properties of the composite material prepared in this embodiment are shown in Tables 2 and 3.

[0065] The neutron shielding performance testing device consists of a polyethylene collimated shielding cylinder, a Cf-252 neutron source, and a high-sensitivity neutron detector. When the material thickness is 1.5, 3, 4.5, 6, 7.5, 9, 10.5, 12, 13.5, or 15 cm, the neutron shielding efficiency is 50.8%, 69.7%, 74.6%, 83.2%, 89.7%, 91.3%, 83.7%, 95.1%, 96.4%, or 99.1%, respectively. The gamma-ray shielding performance testing device consists of a lead collimated shielding cylinder, a Cs-137 gamma source, and a portable radiation detector. When the material thickness is 1.5, 3, 4.5, 6, 7.5, 9, 10.5, 12, 13.5, or 15 cm, the gamma-ray shielding efficiency is 14.4%, 26.3%, 33.8%, 40.9%, 48.2%, 53.6%, 58.8%, 63.2%, 68.1%, or 72.1%, respectively.

[0066] Example 4

[0067] Weigh 0.01 mol of samarium nitrate hexahydrate powder and 0.3 mol of urea powder using an electronic analytical balance and place them in an Erlenmeyer flask. Add 800 ml of ultrapure water to the flask and stir at room temperature for 30 min to completely dissolve and mix thoroughly. Then, transfer the Erlenmeyer flask containing the reaction solution to an oil bath, maintain the temperature of the reaction solution at 85°C, and react for 3 h. After the reaction is complete, transfer the solution from the Erlenmeyer flask to a centrifuge tube and centrifuge at 8000 rpm for about 4 min. After centrifugation, discard the supernatant in the centrifuge tube, add ultrapure water to the centrifuge tube, and continue centrifugation. Repeat the above operation 5 times until the supernatant is clear. Then, add ethanol to the centrifuge tube and continue centrifugation. After each centrifugation, discard the supernatant in the centrifuge tube, add ethanol to the centrifuge tube, and continue centrifugation. Repeat the above process 5 times until the supernatant is clear, indicating that the impurities in the precipitate in the centrifuge tube have been completely removed. The precipitate in the centrifuge tube was then placed in an oven and dried at 60°C for 6 hours. Finally, the dried precipitate was placed in a tube furnace and sintered at 800°C for 2 hours to obtain micron-plate structured Sm2O3, labeled as micron-plate Sm2O3 (R = 1:30).

[0068] SEM images, XRD patterns, N2 adsorption-desorption isotherms and pore size distribution diagrams, and BET specific surface area parameters of micron-sized Sm2O3 (R=1:30) are shown below. Figure 1 (d), Figure 2 , Figure 4 As shown in Table 1, the XRD pattern indicates that the micron-sized Sm₂O₃ (R = 1:30) belongs to the cubic crystal system with space group Ia⁻³(206). SEM images and BET measurements show that Sm₂O₃ exhibits a micron-sized plate morphology with gaps, and the plate size is approximately 3.5 μm. The hysteresis loop on the nitrogen adsorption-desorption curve in the BET test is of the H₃ type, indicating that the prepared Sm₂O₃ is a plate-like material with gaps. Its BET specific surface area, pore volume, and average pore diameter are 9.12 m² / s². 2 / g, 0.062cm 3 / g, 24.82nm. Table 1 shows the BET specific surface area and other parameters of the micron-plate structured samarium oxide filler.

[0069] Table 1

[0070]

[0071] Weigh 36g of Sm2O3 (R=1:30) powder and 72g of... B4C powder and 252g of high-density polyethylene powder were mixed in a high-energy ball mill at 900rpm / min for 10min. The mixture was then placed in an internal mixer at 210℃ and kneaded for 20min. The kneaded product was then crushed in a crusher with a 3mm screen size for 60min. The crushed particles were placed in a hot press mold with release paper, and hot-pressed under the following conditions: first, pre-pressing at 220℃ and 0MPa (pressure applied by the hot press mold) for 10min; then, holding at 220℃ and 30MPa for 30min; and finally, holding at 240℃ and 55MPa for 90min. After cooling to room temperature and depressurizing, a micron-sized Sm2O3 (R=1:30) / B4C / HDPE neutron-gamma shielding composite material was obtained.

[0072] The heat resistance and mechanical properties of the composite material prepared in this embodiment are shown in Tables 2 and 3. Table 2 shows the thermal stability parameters of the neutron-gamma composite shielding material containing micron-sized Sm2O3 filler.

[0073] Table 2

[0074]

[0075] Table 3 Mechanical property parameters of neutron-gamma composite shielding material containing micron-sized Sm2O3 filler.

[0076] Table 3

[0077]

[0078] The neutron shielding performance testing device consists of a polyethylene collimated shielding cylinder, a Cf-252 neutron source, and a high-sensitivity neutron detector. When the material thickness is 1.5 cm, the neutron shielding efficiency is 43.1%. The gamma-ray shielding performance testing device consists of a lead collimated shielding cylinder, a Cs-137 gamma source, and a portable radiation detector. When the material thickness is 1.5 cm, the gamma-ray shielding efficiency is 13.1%.

[0079] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A neutron-gamma composite shielding material, characterized in that, Using samarium oxide with a micron-scale structure as a neutron and gamma ray absorber, boron carbide as a neutron absorber, and high-density polyethylene as the matrix material, the mass content of each component in the neutron-gamma composite shielding material is as follows, based on the total mass of the material: high-density polyethylene: 67~72wt%, boron carbide: 17~22wt%, and samarium oxide with a micron-scale structure: 8~12wt%; the density of the high-density polyethylene is 0.90 g / cm³. 3 ~0.99g / cm 3 ; The samarium oxide particles with the micron-plate structure have a particle size of 0.1-10 μm and a specific surface area of ​​1-100 m². 2 / g, pore volume 0.01~0.5cm³ 3 / g, with an average pore diameter of 1~100nm; The micron-plate structured samarium oxide was prepared by the following method: (1) Weigh samarium nitrate and urea, with a molar ratio of samarium nitrate to urea of ​​0.01 to 10; (2) Dissolve samarium nitrate and urea in ultrapure water and stir at room temperature for 1 to 120 min to mix the solution evenly. Then, keep the mixed solution at 60 to 140 °C for 0.1 to 8 hours to obtain an emulsion. (3) Centrifuge the emulsion to obtain a precipitate, and wash the precipitate; (4) The washed precipitate is placed in an oven and dried at a constant temperature of 30~120℃ for 0.1~24h, and then transferred to a heating furnace and sintered at a constant temperature of 300℃~1900℃ for 0.1~12h to obtain the micron plate structured samarium oxide.

2. A method for preparing the neutron-gamma composite shielding material as described in claim 1, characterized in that, Includes the following steps: Samarium oxide with micron-sized plate structure, boron carbide, and high-density polyethylene are ball-milled for 1-60 minutes to ensure uniform mixing. The mixed powder is then placed in an internal mixer and mixed at 140-240°C for 1-60 minutes. The resulting product is then crushed in a crusher. The crushed particles are placed in a hot press mold and hot-pressed under the following conditions: first, holding at 140-400°C with a pressure of 0-20 MPa for 1-30 minutes; then holding at 180-400°C with a pressure of 5-90 MPa for 10-100 minutes; and finally, holding at 190-400°C with a pressure of 20-90 MPa for 10-200 minutes. After cooling, depressurization, and demolding, the neutron-gamma composite shielding material was obtained.

3. The preparation method according to claim 2, characterized in that, The screen aperture of the crusher is 0.5~50mm.

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