Gadolinia / samaria / europia-containing zirconium hydride-based moderating shielding material, and preparation method and application thereof

Abstract

A zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide, its preparation method, and its application belong to the field of radiation shielding technology. It solves the problems of hydrogen loss, cracking, and poor thermal stability inherent in existing zirconium hydride materials. The material of this invention has a density of 5.58–5.71 g / cm³. 3 The hydrogen content is 1.6wt%~1.83wt%. The mass proportions of each substance in the total amount of ZrH2, Gd2O3, Sm2O3 and Eu2O3 are: 99%≤ZrH2<100%, 0%≤Gd2O3≤1%, 0%≤Sm2O3≤1%, 0%≤Eu2O3≤1%, 0%<Gd2O3+Sm2O3+Eu2O3≤1%. The hydrogen release initiation temperature is ≥557℃. Utilizing multi-element synergistic absorption, the shielding efficiency for 1MeV fast neutrons is ≥97.5%, and the thermal neutron proportion is reduced by ≥80%. It is suitable for small nuclear power reactors below 600℃.

Description

Technical Field

[0001] This invention belongs to the field of radiation shielding materials technology, specifically relating to a zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide, its preparation method and application, and particularly to the application of this zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide as a moderation shielding material for nuclear power reactors below 600°C. Background Technology

[0002] As nuclear energy technology advances towards compactness, miniaturization, and high safety, particularly in micro-nuclear power systems (such as space nuclear power sources, offshore mobile reactors, and modular reactors), the demand for high-performance neutron moderation shielding materials is becoming increasingly urgent. These materials not only need excellent neutron moderation and absorption capabilities but also good thermal stability, mechanical strength, and long-term service reliability. Traditional shielding materials such as polyethylene and paraffin have high hydrogen content but are not heat-resistant (<200℃), failing to meet the requirements of high-temperature reactor cores (>200℃). Zirconium hydride possesses strong moderation capabilities and high-temperature resistance (>200℃), reducing the mass and volume of moderation shields in micro-nuclear power reactors, making it an important candidate material for moderators in micro-nuclear power reactors. However, zirconium hydride's primary function is neutron moderation; its absorption efficiency for moderated thermal neutrons is very low. During hydrogenation, lattice expansion generates internal stress, leading to cracking and the formation of hydrogen escape channels, resulting in a sharp decrease in density and mechanical strength. Experiments show that pure zirconium hydride bulk materials can experience a hydrogen loss rate of up to 15% after 100 hours of service at 500℃. During heating, zirconium hydride undergoes a phase transition from ε to δ phase (fcc) to γ ​​phase (bcc) to β-Zr. Hydrogen escape not only weakens its neutron moderation ability but also causes lattice distortion and phase transition stress accumulation, inducing the formation of a microcrack network. These cracks act as rapid channels for hydrogen diffusion, accelerating hydrogen loss, and significantly reduce the material's mechanical strength and density, ultimately leading to material failure. Excessive hydrogen content in zirconium hydride leads to brittleness and intensified cracking, while insufficient hydrogen content reduces neutron moderation performance. Traditional zirconium hydride materials suffer from hydrogen loss, phase transition cracking, and poor thermal stability under high temperature or irradiation conditions, limiting their further application in advanced nuclear systems.

[0003] In recent years, researchers have attempted to absorb and shield neutrons by doping elements such as Gd, Er, and B as neutron poisons. However, direct alloying of rare earth metals with zirconium is difficult, and the composition control is not uniform. The boiling points of Sm (1791℃) and Eu (1597℃) are significantly lower than the melting point of zirconium (1852℃). During smelting, rare earth vapors pollute the furnace cavity, resulting in a composition deviation of >30%. Rare earth elements readily form brittle intermetallic compounds such as Zr5Gd and Zr3Sm with zirconium, which deteriorates the material's plasticity and affects subsequent processing and service performance. Directly using metal powders for mixing and sintering also makes it difficult to achieve uniform element distribution, easily leading to agglomeration and segregation, which seriously affects the consistency of material properties. Although metal hydrides such as gadolinium and samarium (GdH2, SmH2, etc.) have high hydrogen content and high neutron absorption performance, their performance is unstable and they easily react with moisture, oxygen, and nitrogen in the air, causing structural components to pulverize. The manufacturing process is difficult, costly, and carries high safety risks. Summary of the Invention

[0004] In view of this, to address the technical problems of hydrogen loss, phase transformation cracking, and poor thermal stability in existing zirconium hydride-based shielding materials, this invention provides a zirconium hydride-based moderation shielding material containing gadolinium oxide / smarium oxide / europium oxide and its preparation method. This invention abandons the traditional smelting route and adopts a synergistic strategy of rare earth oxide doping + powder metallurgy + gradient temperature-controlled hydrogen replenishment to construct an integrated zirconium hydride-based moderation shielding material containing Gd₂O₃ / Sm₂O₃ / Eu₂O₃. By introducing highly stable rare earth oxides, not only is the volatilization of low-boiling-point metals avoided, but the grain boundary pinning effect is also used to refine grains, solidify hydrogen atoms, and inhibit crack propagation. Furthermore, by leveraging the complementary absorption characteristics of various rare earth elements in different neutron energy ranges, efficient full-spectrum neutron regulation is achieved, making it suitable for small nuclear power reactors.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] In a first aspect, the present invention provides a zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide, with zirconium hydride as the matrix and one or more of gadolinium oxide, samarium oxide, and europium oxide as dopants, having a density of 5.58–5.71 g / cm³. 3 The hydrogen content is controlled between 1.6 wt% and 1.85 wt%. The mass proportions of each substance in the total amount of ZrH2, Sm2O3, Eu2O3, and Gd2O3 are: 99% ≤ ZrH2 < 100%, 0% ≤ Gd2O3 ≤ 1%, 0% ≤ Sm2O3 ≤ 1%, 0% ≤ Eu2O3 ≤ 1%, 0% < Gd2O3 + Sm2O3 + Eu2O3 ≤ 1%, ZrH 2+ Gd2O3+Sm2O3+Eu2O3=100%.

[0007] Preferably, zirconium hydride is used as the matrix and gadolinium oxide is used as the dopant. The mass ratio of each substance in the total amount of ZrH2 and Gd2O3 is: ZrH2=99% and Gd2O3=1%.

[0008] Preferably, zirconium hydride is used as the matrix and samarium oxide is used as the dopant. The mass ratio of each substance in the total amount of ZrH2 and Sm2O3 is: ZrH2=99% and Sm2O3=1%.

[0009] Preferably, zirconium hydride is used as the matrix and europium oxide is used as the dopant. The mass ratio of each substance in the total amount of ZrH2 and Eu2O3 is: ZrH2=99% and Eu2O3=1%.

[0010] Preferably, zirconium hydride is used as the matrix, and gadolinium oxide and europium oxide are used as dopants. The mass proportions of each substance in the total amount of ZrH2, Eu2O3 and Gd2O3 are: ZrH2=99%, Gd2O3=0.5%, Eu2O3=0.5%.

[0011] Preferably, zirconium hydride is used as the matrix, and gadolinium oxide and samarium oxide are used as dopants. The mass proportions of each substance in the total amount of ZrH2, Sm2O3 and Gd2O3 are: ZrH2=99%, Gd2O3=0.5%, and Sm2O3=0.5%.

[0012] Preferably, zirconium hydride is used as the matrix, and samarium oxide and europium oxide are used as dopants. The mass proportions of each substance in the total amount of ZrH2, Sm2O3 and Eu2O3 are: ZrH2=99%, Sm2O3=0.5%, Eu2O3=0.5%.

[0013] Preferably, zirconium hydride is used as the matrix, and gadolinium oxide, samarium oxide and europium oxide are used as dopants. The mass proportions of each substance in the total amount of ZrH2, Sm2O3, Eu2O3 and Gd2O3 are: ZrH2=99%, Gd2O3=0.33%, Sm2O3=0.33%, Eu2O3=0.33%.

[0014] In a second aspect, the present invention provides a zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide, comprising the following steps:

[0015] (1) Zirconium powder is placed in a hydrogenation furnace for hydrogenation, and the hydrogenation time and pressure are controlled to obtain hydride zirconium with a hydrogen content of 1.6wt% to 1.85wt%;

[0016] (2) Weigh zirconium hydride, gadolinium oxide, europium oxide and samarium oxide according to the required proportions, and ball mill them evenly under an inert atmosphere to obtain a mixed powder;

[0017] (3) The mixed powder is pressed into shape, and the sintered blank is subjected to secondary hydrogenation to obtain a zirconium hydride-based moderating shielding material containing gadolinium oxide / samarium oxide / europium oxide.

[0018] Preferably, step (1) involves: evacuating the hydrogenation furnace to a vacuum level of ≤1.3×10⁻⁶. -2 After Pa, an inert atmosphere is introduced until the pressure reaches 0.1–0.3 MPa. Under the protection of the inert atmosphere, zirconium powder with a particle size less than 100 μm is transferred to the hydrogenation furnace, and a vacuum is drawn to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.3-1.0 MPa, the temperature is raised to 300-450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is then complete, and zirconium hydride with a hydrogen storage capacity of 1.6wt%-1.85wt% is obtained.

[0019] Preferably, the process of step (2) is as follows: weigh zirconium hydride, gadolinium oxide, europium oxide and samarium oxide according to the required ratio, add them to a nanoball mill placed in an inert atmosphere, and ball mill them with a ball-to-material ratio of 10:1 to 20:1, a rotation speed of 400 to 600 rpm and a time of 6 to 12 hours to obtain a mixed powder with an average particle size ≤ 80 nm.

[0020] Preferably, in step (3), the pressing process is as follows: the mixed powder is loaded into a cold press mold, pre-formed under a pressure of 3.5 to 5 tons for 5 to 10 minutes, and after demolding, it is wrapped with carbon paper, placed in a cold isostatic press and pressurized to 240 to 350 MPa for 18 to 30 minutes. The resulting blank is then encapsulated in a quartz tube and vacuumed to ≤1.2 × 10⁻⁶ MPa. -2 After Pa, an inert atmosphere is introduced to 0.03-0.1 MPa, and then the furnace is placed in a muffle furnace and heated to 750-900℃ at a heating rate of 10-15℃ / min. The temperature is held for 100-200 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0021] Preferably, in step (3), the secondary hydrogenation process is as follows: the sintered billet is placed in a hydrogenation furnace, and a vacuum is drawn until the vacuum degree is ≤1.3×10⁻⁶. -2 At a pressure of 0.1–0.3 MPa, an inert atmosphere is introduced to clean the furnace, and then a vacuum is evacuated to a vacuum degree ≤1.3 × 10⁻⁶. -2The pressure is increased to 0.01–0.1 MPa by introducing an inert atmosphere, followed by hydrogen gas to 0.25–0.35 MPa. The hydrogen gas supply is then stopped, and the temperature is increased to 195–205 °C at a rate of 1.5–2 °C / min and held for 30–40 min. The temperature is then increased to 300–310 °C at a rate of 1–3 °C / min and held for 50–60 min. The hydrogen pressure in the hydrogenation furnace is adjusted to 0.75–1.25 MPa, and the temperature is increased to 390–410 °C at a rate of 0.5–2 °C / min and held for 6–8 h. The hydrogen pressure is then maintained, and the temperature is lowered to room temperature. The hydrogen gas is discharged, and the furnace is continuously purged with an inert atmosphere for 3–8 min. The furnace is then opened to obtain a zirconium hydride-based moderating shielding material containing gadolinium oxide, samarium oxide, and europium oxide.

[0022] More preferably, the inert atmosphere is argon gas, and the purity of the argon gas is ≥99.99%.

[0023] More preferably, the purity of the hydrogen gas is ≥99.999%.

[0024] Thirdly, the present invention also provides an application of a zirconium hydride-based moderation shielding material of gadolinium oxide / samarium oxide / europium oxide as a moderation shielding material for nuclear power reactors below 600°C.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The present invention relates to a zirconium hydride-based moderation and shielding material containing gadolinium oxide / samarium oxide / europium oxide, in which at least one rare earth oxide from samarium oxide, europium oxide, and gadolinium oxide is doped into zirconium hydride. These dopants possess ultra-high fast neutron (energy > 1 eV) moderation performance. Furthermore, since rare earth elements such as samarium, europium, and gadolinium all have large neutron absorption cross sections (Gd: 49000 barn, Sm: 5600 barn, Eu: 4600 barn), each exhibits unique advantages in neutron moderation at different energy levels. Through synergistic and complementary effects, they achieve comprehensive moderation and shielding of neutrons in multiple energy levels (including fast neutrons, thermal neutrons, and slow neutrons), significantly enhancing the neutron moderation efficiency and shielding effect of the material. Testing revealed that through the synergy of Gd₂O₃ / Sm₂O₃ / Eu₂O₃ and ZrH₂, Gd / Sm / Eu captures thermal neutrons and H moderates fast neutrons, achieving full-spectrum neutron moderation shielding. Compared to pure zirconium hydride (fast neutron absorption efficiency of 92.4%), doping with 1% Gd₂O₃ / Sm₂O₃ / Eu₂O₃ can improve the overall shielding efficiency for 1MeV fast neutrons by more than 5%. The absorption rate of 1MeV neutrons by the 15cm thick shielding material reaches more than 97.5%, and the proportion of neutrons in the thermal neutron segment (<1.0eV) is reduced by more than 80%, achieving optimal overall performance of multi-band neutron moderation shielding.

[0027] The present invention relates to a zirconium hydride-based moderation and shielding material containing gadolinium oxide, samarium oxide, and europium oxide. Gadolinium, samarium, and europium possess both high thermal neutron absorption cross-sections and hydrogen trapping effects, simultaneously addressing the problems of hydrogen escape and neutron shielding. A zirconium hydride matrix dominated by the δ or β phase is formed, in which the doped rare earth oxides are uniformly distributed at grain boundaries and within the grains. The proportion of hydrogen-induced cracks is ≤3%, reducing the material's brittleness and cracking, and suppressing hydrogen escape at high temperatures.

[0028] The zirconium hydride-based moderating shielding material containing gadolinium oxide / samarium oxide / europium oxide of the present invention utilizes the grain boundary pinning effect of samarium oxide, europium oxide and gadolinium oxide to refine grains and anchor hydrogen atoms, inhibit hydrogen-induced crack propagation, reduce material brittleness and reduce lattice expansion stress.

[0029] The zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide of the present invention increases the hydrogen decomposition temperature and reduces hydrogen loss during high-temperature service by utilizing the high binding energy of rare earth elements.

[0030] The present invention relates to a zirconium hydride-based moderation and shielding material containing gadolinium oxide / samarium oxide / europium oxide. Gd₂O₃ / Sm₂O₃ / Eu₂O₃ is added to zirconium hydride to form a Gd-Sm-Eu-Zr-O composite interface phase with the ZrH₂ matrix. The interface layer contains various chemical bonds such as Zr-O, Gd-O, Sm-O, and Eu-O. Furthermore, rare earth metals (Gd, Sm, Eu) are elements with strong hydrogen affinity among the rare earth groups, and the oxide interface formed by them and O exhibits strong chemisorption of hydrogen atoms. The crystal forms and lattice parameters of Gd₂O₃, Sm₂O₃, and Eu₂O₃ differ significantly from those of the ZrH₂ matrix. When combined, they cannot form a perfect coherent lattice, inevitably resulting in lattice distortion and dislocation defects at the interface. The spatial interstitials formed by these defects provide physical adsorption sites for hydrogen atoms. The interface layer is not a homogeneous phase structure, but rather a defective region with a large number of lattice distortions, interface dislocations, phase boundary gaps, and chemical heterogeneous phase bonding sites. The efficient hydrogen trap constructed by the composite interface layer effectively increases the hydrogen release temperature of the moderation shielding material and enhances its high-temperature thermal stability.

[0031] The present invention relates to a zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide, with a Sm₂O₃ / Eu₂O₃ ≤ 1% synergistic valence state transition energy dissipation mechanism, and Eu₂O₃... 3+ / Eu 2+ With Sm 3+ / Sm 2+ Under fast neutron irradiation, valence state oscillations occur, and displacement damage energy is consumed through electron capture, thereby enhancing the ability to absorb secondary gamma rays, radiation resistance, and radiation-induced swelling.

[0032] The zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide of the present invention, Gd2O3 / Sm2O3 / Eu2O3, has a high melting point, which improves the high temperature stability of the material. The large hydrogen release initiation temperature is ≥580℃, and the thermal stability at 500~590℃ is significantly better than that of undoped zirconium hydride.

[0033] The preparation method of this invention adopts an integrated hydrogenation process technology of "temperature-pressure interlock control + inert atmosphere replacement" to ensure the preparation process is safe and efficient, prevent fire, oxidation, explosion, impurities, etc., improve hydrogenation efficiency and product purity, and is suitable for the preparation of nuclear-grade materials with high safety requirements.

[0034] The preparation method of this invention employs a mechanical alloying-induced interfacial metallurgical method for nanoscale high-performance ball milling and mixing. The resulting composite powder has an average particle size ≤80nm, uniform distribution of each component, and elemental segregation <3%. This process effectively breaks the original powder agglomeration state, introduces lattice strain and high-density interfaces, and significantly improves the subsequent sintering density and material service stability.

[0035] The preparation method of this invention adopts "cold pressing preforming + cold isostatic pressing + gradient temperature and pressure coupling hydrogen replenishment process". The cold pressing preforming and cold isostatic pressing process obtain a high-density bulk material and reduce internal porosity. The gradient temperature and pressure coupling hydrogen replenishment process effectively and gradually releases internal stress, promotes deep penetration of hydrogen atoms, significantly reduces the probability of crack formation, and reduces the material crack rate to below 3%.

[0036] The preparation method of this invention avoids the volatilization problem of low-boiling-point rare earth elements and the safety issues in the preparation process, and successfully prepares a zirconium hydride-based integrated moderation and shielding material containing gadolinium oxide / samarium oxide / europium oxide, which is suitable for moderation and shielding structural components of mobile micro-nuclear power reactors. Attached Figure Description

[0037] Figure 1 The image shows the XRD pattern of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of this invention.

[0038] Figure 2 This is a SEM image of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of the present invention.

[0039] Figure 3 EDS analysis of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of the present invention; wherein, a is the overall compositional distribution of the doped zirconium hydride-based moderation shielding material; b is the Zr compositional distribution, c is the Sm compositional distribution, d is the Eu compositional distribution, e is the Gd compositional distribution, and f is the O compositional distribution.

[0040] Figure 4The thermal dehydrogenation temperature curve of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of the present invention is shown.

[0041] Figure 5 This is a physical image of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of the present invention.

[0042] Figure 6 This is a physical image of the doped zirconium hydride-based moderation shielding material prepared in Comparative Example 1 of this invention. Detailed Implementation

[0043] To further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0044] The present invention relates to a zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide, with δ-phase or β-phase zirconium hydride as the matrix and one or more of gadolinium oxide, samarium oxide, and europium oxide as dopants, having a density of 5.58–5.71 g / cm³. 3 The hydrogen content is controlled between 1.6 wt% and 1.85 wt%. The mass proportions of each substance in the total amount of ZrH2, Gd2O3, Sm2O3, and Eu2O3 are: 99% ≤ ZrH2 < 100%, 0% ≤ Gd2O3 ≤ 1%, 0% ≤ Sm2O3 ≤ 1%, 0% ≤ Eu2O3 ≤ 1%, 0% < Gd2O3 + Sm2O3 + Eu2O3 ≤ 1%, ZrH 2+ Gd2O3+Sm2O3+Eu2O3=100%.

[0045] In this invention, the doping form is selected from one of the following: single doping: containing only Gd2O3, or only Sm2O3, or only Eu2O3; binary co-doping: containing Gd2O3+Sm2O3, containing Gd2O3+Eu2O3, or containing Sm2O3+Eu2O3; ternary composite doping: containing Gd2O3, Sm2O3, and Eu2O3 simultaneously. For example, if only gadolinium oxide is doped, ZrH2=99%, Gd2O3=1%; if only samarium oxide is doped, ZrH2=99%, Sm2O3=1%; if only europium oxide is doped, ZrH2=99%, Eu2O3=1%; if gadolinium oxide and samarium oxide are doped, preferably ZrH2=99%, Gd2O3=0.5%, Sm2O3=0.5%; if gadolinium oxide and europium oxide are doped, preferably ZrH2=99%, Gd2O3=0.5%, Sm2O3=0.5%. ZrH2=99%, Gd2O3=0.5%, Eu2O3=0.5%; if doped with samarium oxide and europium oxide, ZrH2=99%, Sm2O3=0.5%, Eu2O3=0.5% is preferred; if doped with gadolinium oxide, samarium oxide and europium oxide, ZrH2=99%, Gd2O3=0.33%, Sm2O3=0.33%, Eu2O3=0.33% is preferred.

[0046] In addition, the material may contain unavoidable trace impurities, such as compounds containing Cr, Fe, C and O.

[0047] The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide of the present invention includes the following steps:

[0048] (1) Zirconium powder is placed in a hydrogenation furnace for hydrogenation, and the hydrogenation time and pressure are controlled to obtain hydride zirconium with a hydrogen content of 1.6wt% to 1.85wt%;

[0049] (2) Weigh zirconium hydride, gadolinium oxide, europium oxide and samarium oxide according to the required proportions, and ball mill them evenly under an inert atmosphere to obtain a mixed powder;

[0050] (3) The mixed powder is pressed into shape, and the sintered blank is subjected to secondary hydrogenation to obtain a zirconium hydride-based moderating shielding material containing gadolinium oxide / samarium oxide / europium oxide.

[0051] In this invention, the preferred step (1) is as follows: evacuating the hydrogenation furnace to a vacuum level of ≤1.3×10⁻⁶. -2 To thoroughly remove residual air, moisture, and other volatile impurities from the furnace and prevent oxidation reactions in subsequent processes, an inert atmosphere is then introduced until the pressure reaches 0.1–0.3 MPa. Oxygen is then replaced using the inert atmosphere. This process of vacuuming and inert atmosphere purging is typically repeated at least twice to ensure the oxygen concentration inside the furnace drops below 20 ppm, completing the furnace cleaning operation. Under an inert atmosphere, such as in a sealed glove box, zirconium powder with a particle size less than 100 μm is transferred to the hydrogenation furnace. The entire process must be rapid and sealed to avoid the risk of oxidation or spontaneous combustion caused by the zirconium powder being exposed to air, ensuring continuous inert atmosphere protection. After charging is complete, the hydrogenation furnace is sealed and evacuated to a pressure ≤1.2 × 10⁻⁶ MPa. - The pressure is set to 2 Pa to eliminate any trace gases that might be introduced. Hydrogen gas is introduced to an initial pressure of 0.3–1.0 MPa to provide sufficient reaction medium for the hydrogenation reaction. A temperature-pressure linkage control program is set using a Siemens PLC, and the heating power and gas flow rate are adjusted in real time via PID feedback. The temperature is slowly increased to the target temperature of 300–450 °C according to the preset program and held at this temperature for 30–180 minutes. During this period, the hydrogen pressure change curve is continuously monitored to track the reaction progress. When the hydrogen pressure tends to stabilize and no longer decreases, it indicates that the zirconium powder has been fully hydrogenated and the reaction has reached its endpoint, thus preparing high-purity zirconium hydride powder with a hydrogen storage capacity of 1.6 wt%–1.85 wt%. This method effectively prevents the risk of material oxidation and ignition through multiple protective measures, significantly improves the efficiency of the hydrogenation reaction and the consistency of the product, and is particularly suitable for the preparation of nuclear-grade zirconium materials with extremely high safety requirements, meeting stringent quality standards and application needs.

[0052] The hydrogenation process of this invention adopts an integrated hydrogenation process technology of "temperature-pressure interlock control + inert atmosphere replacement" to ensure the preparation process is safe and efficient and to prevent fire, oxidation, explosion, impurities, etc.

[0053] In this invention, step (2) involves weighing zirconium hydride, gadolinium oxide, europium oxide, and samarium oxide according to the required proportions and adding them to a nano-ball mill. The mill is then placed in an inert atmosphere for nanoscale mechanical alloying treatment to prevent oxidation or contamination of the powder during processing and to ensure material purity. The ball-to-powder ratio is controlled between 10:1 and 20:1 to optimize grinding efficiency and energy input. The rotation speed is set to 400–600 rpm to ensure sufficient mechanical collision and shearing action; the processing time lasts 6–12 hours to promote thorough powder refinement and alloying. The resulting mixed powder has an average particle size ≤80 nm, highly uniform distribution of each component, and a strict elemental segregation of less than 3%, indicating that the process effectively achieves uniform mixing at the nanoscale. This process, through high-intensity mechanical energy input, effectively breaks the agglomeration of the original powder, introducing significant lattice strain and high-density interface defects, thereby providing more activation energy for the subsequent sintering process and significantly improving sintering density and the service stability of the material under high temperature or stress.

[0054] In this invention, step (3) involves the following pressing process: The mixed powder is loaded into a cold-press mold to ensure uniform powder distribution and avoid molding defects; pre-forming is performed under a pressure of 3.5–5 tons for 5–10 minutes. This step initially compacts the powder, forming a green body with a certain strength. After demolding, the green body is wrapped in carbon paper to effectively prevent external gas penetration and ensure purity in subsequent processing. The sealed green body is placed in a cold isostatic pressing device, pressurized to 240–350 MPa, and held for 18–30 minutes. Through uniform pressure in all directions, the microstructure is further densified, reducing internal porosity and defects. The resulting green body is then encapsulated in a clean quartz tube and evacuated to ≤1.2 × 10⁻⁶. -2 The pressure is increased to 0.03–0.1 MPa to thoroughly remove air and volatile impurities from the quartz tube. Then, an inert atmosphere is introduced to create a stable protective environment, preventing oxidation or unnecessary chemical reactions at high temperatures. The quartz tube is then placed in a muffle furnace and heated to 750–900 °C at a rate of 10–15 °C / min to ensure uniform temperature rise and avoid thermal stress cracking. The temperature is held at the target temperature for 100–200 min to complete the solid-state sintering process, promoting diffusion and bonding between powder particles, thereby achieving densification and microstructure optimization. Finally, the tube is cooled to room temperature in the furnace at a slow cooling rate to reduce internal thermal stress and residual porosity. After opening the tube, a sintered green body is obtained, characterized by high density, low porosity, and high quality.

[0055] The sintering process of this invention adopts a combination of cold molding preforming and isostatic pressing densification multi-stage pressure coupling molding technology to obtain high-density bulk materials and reduce internal porosity.

[0056] In this invention, step (3) involves the following secondary hydrogenation process: placing the sintered billet in a hydrogenation furnace and evacuating it to a vacuum level ≤ 1.3 × 10⁻⁶. -2 At a pressure of 0.1–0.3 MPa, an inert atmosphere is introduced to clean the furnace, and then a vacuum is evacuated to a vacuum degree ≤1.3 × 10⁻⁶. -2 The pressure is increased to 0.01–0.1 MPa by introducing an inert atmosphere, followed by hydrogen gas to 0.25–0.35 MPa. The hydrogen gas supply is then stopped, and the temperature is increased to 195–205 °C at a rate of 1.5–2 °C / min and held for 30–40 min. The temperature is then increased to 300–310 °C at a rate of 1–3 °C / min and held for 50–60 min. The hydrogen pressure in the hydrogenation furnace is adjusted to 0.75–1.25 MPa, and the temperature is increased to 390–410 °C at a rate of 0.5–2 °C / min and held for 6–8 h. The hydrogen pressure is then maintained, and the temperature is lowered to room temperature. The hydrogen gas is discharged, and the furnace is continuously purged with an inert atmosphere for 3–8 min. The furnace is then opened to obtain a zirconium hydride-based moderating shielding material containing gadolinium oxide, samarium oxide, and europium oxide.

[0057] The secondary hydrogenation of this invention employs gradient pressure and temperature coupled hydrogen replenishment, multi-temperature staged temperature control, and gradual pressure regulation to effectively and gradually release internal stress, promote deep hydrogen atom penetration, and significantly reduce the probability of crack formation.

[0058] In this invention, the inert atmosphere is argon, and the purity of the argon is ≥99.99%.

[0059] In this invention, the purity of hydrogen is ≥99.999%.

[0060] In this invention, the hydrogen content of the zirconium hydride obtained in step (1) is 1.6wt% to 1.85wt%, and the content of the shielding material obtained in step (3) is also 1.6wt% to 1.85wt%. It should be noted that in this invention, the rare earth oxides doped are very few, so they hardly affect the hydrogen content.

[0061] The zirconium hydride-based moderator shielding material of gadolinium oxide / samarium oxide / europium oxide of the present invention can be used as a moderator shielding material for nuclear power reactors below 600°C.

[0062] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to embodiments.

[0063] In the following examples and comparative examples, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, all materials, reagents, apparatus, instruments, and equipment used in the following examples and comparative examples are commercially available. Specifically, sponge zirconium, gadolinium oxide, europium oxide, and samarium oxide are all commercially available. Argon gas purity ≥ 99.99%; hydrogen gas purity ≥ 99.999%. Room temperature is 20–30°C.

[0064] Example 1

[0065] A zirconium hydride-based moderation shielding material containing gadolinium oxide, with zirconium hydride as the matrix and gadolinium oxide as the dopant, has a density of 5.71 g / cm³. 3 The hydrogen content is controlled at 1.81 wt%, and the mass ratio of each substance in the total amount of ZrH2 and Gd2O3 is: ZrH2=99%, Gd2O3=1%.

[0066] The preparation method of the above-mentioned gadolinium oxide-containing zirconium hydride-based moderation and shielding material:

[0067] (1) Evacuate the hydrogenation furnace to ≤1.3×10 -2 After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.4MPa, the temperature is raised to 450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is then complete, and zirconium hydride with a hydrogen content of 1.81wt% is obtained.

[0068] (2) Weigh zirconium hydride and gadolinium oxide according to the required ratio and place them in a nanoball mill. Under argon protection, ball milling is carried out at a ball-to-material ratio of 10:1, a rotation speed of 400 rpm, and a time of 10 h to obtain a mixed powder with an average particle size ≤80 nm. The components are evenly distributed and the elemental segregation is less than 3%.

[0069] (3) The mixed powder is loaded into a cold press mold with a diameter of 50 mm, pre-formed under a pressure of 3.5 tons for 5 min, demolded, wrapped in carbon paper, placed in a cold isostatic press and pressurized to 300 MPa for 20 min, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2×10 -2 After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0070] (4) Place the sintered green body in a hydrogenation furnace and evacuate it to a vacuum degree ≤1.3×10 -2At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2 Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.81 wt%, yielding a gadolinium oxide-containing zirconium hydride-based moderation shielding material.

[0071] Example 2

[0072] A zirconium hydride-based moderation shielding material containing samarium oxide, with zirconium hydride as the matrix and samarium oxide as the dopant, has a density of 5.58 g / cm³. 3 The hydrogen content is controlled at 1.83 wt%, and the mass ratio of each substance in the total amount of ZrH2 and Sm2O3 is: ZrH2=99%, Sm2O3=1%.

[0073] The preparation method of the above-mentioned samarium oxide-containing zirconium hydride-based moderation and shielding material:

[0074] (1) Evacuate the hydrogenation furnace to ≤1.3×10 -2 After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.45MPa, the temperature is raised to 450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is completed, and zirconium hydride with a hydrogen content of 1.83wt% is obtained.

[0075] (2) Weigh zirconium hydride and samarium oxide according to the required ratio and place them in a nanoball mill. Under argon protection, ball milling is carried out at a ball-to-material ratio of 10:1, a rotation speed of 400 rpm, and a time of 10 h to obtain a mixed powder with an average particle size ≤80 nm. The components are evenly distributed and the elemental segregation is less than 3%.

[0076] (3) The mixed powder is loaded into a cold press mold with a diameter of 50 mm, pre-formed under a pressure of 3.5 tons for 5 min, demolded, wrapped in carbon paper, placed in a cold isostatic press and pressurized to 300 MPa for 20 min, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2×10 -2After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0077] (4) Place the sintered green body in a hydrogenation furnace and evacuate it to a vacuum degree ≤1.3×10 -2 At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2 Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.83 wt%, yielding a samarium oxide-containing zirconium-based moderation shielding material.

[0078] Example 3

[0079] A zirconium hydride-based moderation shielding material containing gadolinium oxide, with zirconium hydride as the matrix and europium oxide as the dopant, has a density of 5.62 g / cm³. 3 The hydrogen content is controlled at 1.80 wt%, and the mass ratio of each substance in the total amount of ZrH2 and Eu2O3 is: ZrH2=99%, Eu2O3=1%.

[0080] The preparation method of the above-mentioned europium oxide-containing zirconium hydride-based moderation and shielding material:

[0081] (1) Evacuate the hydrogenation furnace to ≤1.3×10 -2 After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.38MPa, the temperature is raised to 450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is then complete, and zirconium hydride with a hydrogen content of 1.80wt% is obtained.

[0082] (2) Weigh zirconium hydride and gadolinium oxide according to the required ratio and place them in a nanoball mill. Under argon protection, ball milling is carried out at a ball-to-material ratio of 10:1, a rotation speed of 400 rpm, and a time of 10 h to obtain a mixed powder with an average particle size ≤80 nm. The components are evenly distributed and the elemental segregation is less than 3%.

[0083] (3) The mixed powder is loaded into a cold press mold with a diameter of 50 mm, pre-formed under a pressure of 3.5 tons for 5 min, demolded, wrapped in carbon paper, placed in a cold isostatic press and pressurized to 300 MPa for 20 min, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2×10 -2 After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0084] (4) Place the sintered green body in a hydrogenation furnace and evacuate it to a vacuum degree ≤1.3×10 -2 At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2 Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.80 wt%, yielding a zirconium hydride-based moderation shielding material containing europium oxide.

[0085] Example 4

[0086] A zirconium hydride-based moderation shielding material containing samarium oxide and europium oxide, with zirconium hydride as the matrix and samarium oxide and europium oxide as dopants, has a density of 5.61 g / cm³. 3 The hydrogen content is controlled at 1.78 wt%, and the mass proportions of each substance in the total amount of ZrH2, Sm2O3, and Eu2O3 are: ZrH2=99%, Sm2O3=0.5%, Eu2O3=0.5%.

[0087] The preparation method of the above-mentioned zirconium hydride-based moderation shielding material containing samarium oxide and europium oxide:

[0088] (1) Evacuate the hydrogenation furnace to ≤1.3×10 -2 After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.3MPa, the temperature is raised to 450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is then complete, and zirconium hydride with a hydrogen content of 1.78wt% is obtained.

[0089] (2) Weigh zirconium hydride, samarium oxide and europium oxide according to the required ratio and place them in a nanoball mill. Under argon protection, ball milling is carried out at a ball-to-material ratio of 10:1, a rotation speed of 400 rpm and a time of 10 h to obtain a mixed powder with an average particle size ≤80 nm. The components are evenly distributed and the elemental segregation is less than 3%.

[0090] (3) The mixed powder is loaded into a cold press mold with a diameter of 50 mm, pre-formed under a pressure of 3.5 tons for 5 min, demolded, wrapped in carbon paper, placed in a cold isostatic press and pressurized to 300 MPa for 20 min, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2×10 -2 After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0091] (4) Place the sintered green body in a hydrogenation furnace and evacuate it to a vacuum degree ≤1.3×10 -2 At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2 Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.78 wt%, yielding a zirconium-based moderation shielding material containing samarium oxide and europium oxide.

[0092] Example 5

[0093] A zirconium hydride-based moderation shielding material containing gadolinium oxide and samarium oxide, with zirconium hydride as the matrix and gadolinium oxide and samarium oxide as dopants, has a density of 5.68 g / cm³. 3 The hydrogen content is controlled at 1.81 wt%, and the mass proportions of each substance in the total amount of ZrH2, Gd2O3 and Sm2O3 are: ZrH2=99%, Gd2O3=0.5%, Sm2O3=0.5%.

[0094] The preparation method of the above-mentioned zirconium hydride-based moderation shielding material containing gadolinium oxide and samarium oxide:

[0095] (1) Evacuate the hydrogenation furnace to ≤1.3×10 -2After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.4MPa, the temperature is raised to 450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is then complete, and zirconium hydride with a hydrogen content of 1.81wt% is obtained.

[0096] (2) Weigh zirconium hydride, gadolinium oxide and samarium oxide according to the required ratio and place them in a nanoball mill. Under argon protection, ball milling is carried out at a ball-to-material ratio of 10:1, a rotation speed of 400 rpm and a time of 10 h to obtain a mixed powder with an average particle size ≤80 nm. The components are evenly distributed and the elemental segregation is less than 3%.

[0097] (3) The mixed powder is loaded into a cold press mold with a diameter of 50 mm, pre-formed under a pressure of 3.5 tons for 5 min, demolded, wrapped in carbon paper, placed in a cold isostatic press and pressurized to 300 MPa for 20 min, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2×10 -2 After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0098] (4) Place the sintered green body in a hydrogenation furnace and evacuate it to a vacuum degree ≤1.3×10 -2 At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2 Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.81 wt%, yielding a zirconium hydride-based moderation shielding material containing gadolinium oxide and samarium oxide.

[0099] Example 6

[0100] A zirconium hydride-based moderation shielding material containing gadolinium oxide and europium oxide, with zirconium hydride as the matrix and gadolinium oxide and europium oxide as dopants, has a density of 5.64 g / cm³. 3The hydrogen content is controlled at 1.79 wt%, and the mass proportions of each substance in the total amount of ZrH2, Gd2O3 and Sm2O3 are: ZrH2=99%, Gd2O3=0.5%, Eu2O3=0.5%.

[0101] The preparation method of the above-mentioned zirconium hydride-based moderation and shielding material containing gadolinium oxide and europium oxide:

[0102] (1) Evacuate the hydrogenation furnace to ≤1.3×10 -2 After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.35MPa, the temperature is raised to 450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is completed, and zirconium hydride with a hydrogen content of 1.79wt% is obtained.

[0103] (2) Weigh zirconium hydride, gadolinium oxide and europium oxide according to the required ratio and place them in a nanoball mill. Under argon protection, ball milling is carried out at a ball-to-material ratio of 10:1, a rotation speed of 400 rpm and a time of 10 h to obtain a mixed powder with an average particle size ≤80 nm. The components are evenly distributed and the elemental segregation is less than 3%.

[0104] (3) The mixed powder is loaded into a cold press mold with a diameter of 50 mm, pre-formed under a pressure of 3.5 tons for 5 min, demolded, wrapped in carbon paper, placed in a cold isostatic press and pressurized to 300 MPa for 20 min, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2×10 -2 After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0105] (4) Place the sintered green body in a hydrogenation furnace and evacuate it to a vacuum degree ≤1.3×10 -2 At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.79 wt%, yielding a zirconium hydride-based moderation shielding material containing gadolinium oxide and europium oxide.

[0106] Example 7

[0107] A zirconium hydride-based moderation shielding material containing gadolinium oxide, samarium oxide, and europium oxide, with zirconium hydride as the matrix and gadolinium oxide, samarium oxide, and europium oxide as dopants, has a density of 5.70 g / cm³. 3 The hydrogen content is controlled at 1.83 wt%. The mass proportions of each substance in the total amount of ZrH2, Gd2O3, Sm2O3, and Eu2O3 are: ZrH2=99%, Gd2O3=0.33%, Sm2O3=0.33%, Eu2O3=0.33%.

[0108] The preparation method of the above-mentioned zirconium hydride-based moderation shielding material containing gadolinium oxide, samarium oxide, and europium oxide:

[0109] (1) Evacuate the hydrogenation furnace to ≤1.3×10 -2 After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.45MPa, the temperature is raised to 450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is completed, and zirconium hydride with a hydrogen content of 1.83wt% is obtained.

[0110] (2) Weigh zirconium hydride, gadolinium oxide, samarium oxide and europium oxide according to the required ratio and place them in a nanoball mill. Under argon protection, ball milling is carried out at a ball-to-material ratio of 10:1, a rotation speed of 400 rpm and a time of 10 h to obtain a mixed powder with an average particle size ≤80 nm. The components are evenly distributed and the elemental segregation is less than 3%.

[0111] (3) The mixed powder is loaded into a cold press mold with a diameter of 50 mm, pre-formed under a pressure of 3.5 tons for 5 min, demolded, wrapped in carbon paper, placed in a cold isostatic press and pressurized to 300 MPa for 20 min, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2×10 -2After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0112] (4) Place the sintered green body in a hydrogenation furnace and evacuate it to a vacuum degree ≤1.3×10 -2 At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2 Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.83 wt%, yielding a zirconium-based moderation shielding material containing gadolinium oxide, samarium oxide, and europium oxide.

[0113] Comparative Example 1

[0114] The hydrogenation furnace was evacuated to a vacuum level of ≤1.3×10⁻⁶. -2 After Pa, argon gas is purged to 0.3 MPa. The process of evacuation and argon purging is repeated at least twice. Then, in a sealed glove box under argon protective atmosphere, zirconium powder with a particle size of 80 μm is transferred to the hydrogenation furnace, and the vacuum is evacuated to ≤1.2 × 10⁻⁶ MPa. - The hydrogenation reaction was completed when hydrogen gas was introduced to an initial pressure of 0.45 MPa, the temperature was raised to 450 °C, and the temperature was maintained until the hydrogen pressure stabilized and no longer decreased. This yielded zirconium hydride with a hydrogen storage capacity of 1.83 wt% and a bulk density of 5.64 g / cm³. 3 ;

[0115] The mixed powder was loaded into a 50mm diameter cold-press mold and pre-formed under 3.5 tons of pressure for 5 minutes. After demolding, it was wrapped in carbon paper and placed in a cold isostatic press, pressurized to 300MPa and held for 20 minutes. The resulting preform was then encapsulated in a quartz tube and evacuated to a vacuum level ≤1.2×10⁻⁶. -2 After Pa, argon gas is introduced to 0.05 MPa, and then placed in a muffle furnace. The temperature is increased to 900°C at a heating rate of 15°C / min, held for 100 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

[0116] The sintered green body is placed in a hydrogenation furnace and evacuated to a vacuum level ≤1.3×10⁻⁶. -2 At pressure Pa, argon gas is introduced to 0.2 MPa for furnace cleaning, and then a vacuum is evacuated to a vacuum degree ≤ 1.3 × 10⁻⁶. -2Argon gas was introduced again to 0.05 MPa, followed by hydrogen gas to 0.35 MPa. The hydrogen gas supply was stopped, and the temperature was increased to 200℃ at a rate of 2℃ / min and held for 30 min. The temperature was then increased to 300℃ at a rate of 3℃ / min and held for 60 min. The hydrogen pressure in the hydrogenation furnace was adjusted to 1.25 MPa, and the temperature was increased to 400℃ at a rate of 2℃ / min and held for 8 h. The hydrogen pressure was then maintained, and the temperature was lowered to room temperature. The hydrogen gas was discharged, and argon gas was continuously introduced to clean the furnace for 8 min. The furnace was then opened, and the hydrogen content was 1.83 wt%, yielding the hydride zirconium-based shielding material.

[0117] The composition of the shielding materials in Examples 1-7 and Comparative Example 1 is shown in Table 1.

[0118] Table 1. Composition of shielding materials in Examples 1-7 and Comparative Example 1

[0119]

[0120] The shielding materials prepared in Examples 1-7 and Comparative Example 1 were subjected to density testing, fast neutron absorption efficiency testing, hydrogen content testing, and hydrogen desorption temperature testing. The fast neutron absorption efficiency was tested using MCNP calculation software based on the Monte Carlo method, performing fast neutron absorption calculations on a 15 cm thick layer at 1 MeV, with the number of neutrons set to 102. 5 The test results are shown in Table 2.

[0121] Table 2 Performance of the shielding materials prepared in Examples 1-7 and Comparative Example 1

[0122]

[0123] As shown in Table 1, the absorption efficiency of pure zirconium hydride shielding material for fast neutrons is 92.4%. Doping with 1% Gd2O3 / Sm2O3 / Eu2O3 can improve the overall shielding efficiency for 1MeV fast neutrons by more than 5%. Through the synergy of Gd2O3 / Sm2O3 / Eu2O3 and ZrH2, Gd / Sm / Eu captures thermal neutrons and H moderates fast neutrons, achieving full-spectrum neutron moderation shielding. Compared with pure zirconium hydride, the absorption rate of 1MeV neutrons for 15cm thick material reaches more than 97.5%, and the proportion of neutrons in the thermal neutron segment (<1.0eV) is reduced by more than 80%, achieving the optimal overall performance of multi-energy segment neutron moderation shielding.

[0124] Figure 1 and Figure 2 The images show the XRD and SEM images of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of this invention. As can be seen from the images, the material composition is consistent with that in Table 1. Through visual observation and SEM observation, the number of cracks in Example 7 is controlled to be less than 3%.

[0125] Figure 3 EDS analysis of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of this invention; the figure shows that Gd2O3 / Sm2O3 / Eu2O3 are uniformly distributed in ZrH2 without agglomeration.

[0126] Figure 4 The thermogravimetric analysis hydrogen release curve of the doped zirconium hydride-based moderation shielding material prepared in Example 7 of the present invention shows that when the temperature exceeds 593°C, the sample will release a large amount of hydrogen.

[0127] Figure 5 and Figure 6 The images show physical pictures of the moderating shielding material prepared in Example 7 and the shielding material prepared in Comparative Example 1, respectively. As can be seen from the images, the shielding material in Comparative Example 1 is completely fragmented. This phenomenon is due to the expansion of the zirconium lattice during hydrogenation, which causes cracking of the profile. The moderating shielding material prepared using the method of this invention does not show any obvious cracks. This indicates that the method of this invention can obtain a high-density, crack-free doped zirconium hydride-based moderating shielding material.

[0128] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. A zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide, characterized in that, Using zirconium hydride as the matrix, and doped with one or more of gadolinium oxide, samarium oxide, and europium oxide, the density is 5.58–5.71 g / cm³. 3 The hydrogen content is controlled between 1.6 wt% and 1.83 wt%. The mass proportions of each substance in the total amount of ZrH2, Sm2O3, Eu2O3, and Gd2O3 are: 99% ≤ ZrH2 < 100%, 0% ≤ Gd2O3 ≤ 1%, 0% ≤ Sm2O3 ≤ 1%, 0% ≤ Eu2O3 ≤ 1%, 0% < Gd2O3 + Sm2O3 + Eu2O3 ≤ 1%, ZrH 2+ Gd2O3+Sm2O3+Eu2O3=100%.

2. The zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to claim 1, characterized in that, Using zirconium hydride as the matrix and gadolinium oxide as the dopant, the mass proportions of each substance in the total ZrH2 and Gd2O3 are: ZrH2 = 99%, Gd2O3 = 1%; Alternatively, using zirconium hydride as the matrix and samarium oxide as the dopant, the mass proportions of each substance in the total ZrH2 and Sm2O3 are: ZrH2 = 99%, Sm2O3 = 1%; Alternatively, using zirconium hydride as the matrix and europium oxide as the dopant, the mass proportions of each substance in the total ZrH2 and Eu2O3 are: ZrH2 = 99%, Eu2O3 = 1%; Alternatively, using zirconium hydride as the matrix and gadolinium oxide and europium oxide as dopants, the mass proportions of each substance in the total amount of ZrH2, Eu2O3 and Gd2O3 are: ZrH2=99%, Gd2O3=0.5%, Eu2O3=0.5%; Alternatively, using zirconium hydride as the matrix and gadolinium oxide and samarium oxide as dopants, the mass proportions of each substance in the total amount of ZrH2, Sm2O3 and Gd2O3 are: ZrH2=99%, Gd2O3=0.5%, Sm2O3=0.5%; Alternatively, using zirconium hydride as the matrix and samarium oxide and europium oxide as dopants, the mass proportions of each substance in the total amount of ZrH2, Sm2O3, and Eu2O3 are: ZrH2 = 99%, Sm2O3 = 0.5%, Eu2O3 = 0.5%; Alternatively, using zirconium hydride as the matrix and gadolinium oxide, samarium oxide, and europium oxide as dopants, the mass proportions of each substance in the total amount of ZrH2, Sm2O3, Eu2O3, and Gd2O3 are: ZrH2=99%, Gd2O3=0.33%, Sm2O3=0.33%, Eu2O3=0.33%.

3. The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to claim 1 or 2, characterized in that, Includes the following steps: (1) Zirconium powder is placed in a hydrogenation furnace for hydrogenation, and the hydrogenation time and pressure are controlled to obtain hydride zirconium with a hydrogen content of 1.6wt% to 1.85wt%; (2) Weigh zirconium hydride, gadolinium oxide, europium oxide and samarium oxide according to the required proportions, and ball mill them evenly under an inert atmosphere to obtain a mixed powder; (3) The mixed powder is pressed into shape, and the sintered blank is subjected to secondary hydrogenation to obtain a zirconium hydride-based moderating shielding material containing gadolinium oxide / samarium oxide / europium oxide.

4. The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to claim 3, characterized in that, The process of step (1) is as follows: evacuate the hydrogenation furnace to a vacuum level of ≤1.3×10⁻⁶. -2 After Pa, an inert atmosphere is introduced until the pressure reaches 0.1–0.3 MPa. Under the protection of the inert atmosphere, zirconium powder with a particle size less than 100 μm is transferred to the hydrogenation furnace, and a vacuum is drawn to ≤1.2 × 10⁻⁶ MPa. - ²Pa, hydrogen gas is introduced to the initial pressure of 0.3-1.0 MPa, the temperature is raised to 300-450℃, and the temperature is maintained until the hydrogen pressure stabilizes and no longer decreases. The hydrogenation reaction is then complete, and zirconium hydride with a hydrogen storage capacity of 1.6wt%-1.85wt% is obtained.

5. The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to claim 3, characterized in that, The process of step (2) is as follows: weigh zirconium hydride, gadolinium oxide, europium oxide and samarium oxide according to the required ratio, add them to a nanoball mill placed in an inert atmosphere, and ball mill them with a ball-to-material ratio of 10:1 to 20:1, a rotation speed of 400 to 600 rpm and a time of 6 to 12 hours to obtain a mixed powder with an average particle size ≤80nm.

6. The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to claim 3, characterized in that, In step (3), the pressing process is as follows: the mixed powder is loaded into a cold press mold and pre-formed under a pressure of 3.5 to 5 tons for 5 to 10 minutes. After demolding, it is wrapped with carbon paper, placed in a cold isostatic press, pressurized to 240 to 350 MPa and held for 18 to 30 minutes, and then the resulting blank is sealed in a quartz tube and vacuumed to ≤1.2 × 10⁻⁶ MPa. -2 After Pa, an inert atmosphere is introduced to 0.03-0.1 MPa, and then the furnace is placed in a muffle furnace and heated to 750-900℃ at a heating rate of 10-15℃ / min. The temperature is held for 100-200 min, and then cooled to room temperature with the furnace to obtain the sintered green body.

7. The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to claim 3, characterized in that, In step (3), the secondary hydrogenation process is as follows: the sintered billet is placed in a hydrogenation furnace, and a vacuum is drawn until the vacuum degree is ≤1.3×10⁻⁶. -2 At a pressure of 0.1–0.3 MPa, an inert atmosphere is introduced to clean the furnace, and then a vacuum is evacuated to a vacuum degree ≤1.3 × 10⁻⁶. -2 The pressure is increased to 0.01–0.1 MPa by introducing an inert atmosphere, followed by hydrogen gas to 0.25–0.35 MPa. The hydrogen gas supply is then stopped, and the temperature is increased to 195–205 °C at a rate of 1.5–2 °C / min and held for 30–40 min. The temperature is then increased to 300–310 °C at a rate of 1–3 °C / min and held for 50–60 min. The hydrogen pressure in the hydrogenation furnace is adjusted to 0.75–1.25 MPa, and the temperature is increased to 390–410 °C at a rate of 0.5–2 °C / min and held for 6–8 h. The hydrogen pressure is then maintained, and the temperature is lowered to room temperature. The hydrogen gas is discharged, and the furnace is continuously purged with an inert atmosphere for 3–8 min. The furnace is then opened to obtain a zirconium hydride-based moderating shielding material containing gadolinium oxide, samarium oxide, and europium oxide.

8. The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to any one of claims 3 to 7, characterized in that, The inert atmosphere used is argon, and the purity of the argon is ≥99.99%.

9. The method for preparing the zirconium hydride-based moderation shielding material containing gadolinium oxide / samarium oxide / europium oxide according to claim 4 or 7, characterized in that, The purity of the hydrogen gas is ≥99.999%.

10. The application of the zirconium hydride-based moderator shielding material containing gadolinium oxide / samarium oxide / europium oxide as described in claim 1 or 2 as a moderator shielding material for nuclear power reactors below 600°C.

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