A samarium / europium / gadolinium-containing zirconium hydride bulk body, a preparation method and application thereof

Abstract

The application provides a samarium / europium / gadolinium-containing zirconium hydride block and a preparation method and application thereof, and relates to the technical field of radiation shielding materials. The samarium / europium / gadolinium-containing zirconium hydride block comprises the following elements with the mass percentage of 95%≤Zr≤99.5%, 0%≤Gd≤5%, 0%≤Sm≤5%, 0%≤Eu≤5%, and 0%<Gd+Sm+Eu≤5%. The preparation method comprises the following steps: respectively hydrogenating sponge zirconium, metal gadolinium, metal europium and metal samarium to obtain corresponding hydride powders; weighing the zirconium hydride, gadolinium hydride, europium hydride and samarium hydride powders according to the required proportion and mixing them uniformly under a protective atmosphere; and pressing and sintering the mixed powders and performing secondary hydrogenation to obtain the samarium / europium / gadolinium-containing zirconium hydride block. The application can significantly improve the absorption of low-energy neutrons by the material, and realizes the preparation of the samarium / europium / gadolinium-containing zirconium hydride block and the accurate regulation of the doping elements.

Description

Technical Field

[0001] This invention relates to the field of radiation shielding materials technology, and in particular to a zirconium hydride bulk containing samarium / europium / gadolinium, its preparation method, and its application. Background Technology

[0002] With the development of nuclear energy technology, the technology of miniature nuclear reactors has become increasingly mature. Miniature reactors typically use liquid metal as a coolant, which has limited neutron moderation effects. Therefore, during reactor operation, a large number of fast neutrons are leaked, necessitating shielding and absorption. Conventional materials have poor shielding and absorption effects on fast neutrons. Before shielding fast neutrons, they need to be moderated. Neutron moderation mainly relies on light nuclides. Materials such as water, paraffin wax, and polyethylene have high hydrogen content, but their long-term service temperature is below 100°C. Zirconium hydride (ZrH2), due to its high hydrogen atom density and extremely high hydrogen decomposition temperature, is an ideal reactor neutron moderator material and is widely used in lightweight, compact reactor designs for neutron moderation and shielding.

[0003] In practical applications, zirconium hydride is typically manufactured into bulk components of a specific shape and density. There are two main manufacturing methods: one is sintering zirconium hydride powder into blocks; the other is direct hydrogenation forming of zirconium materials. The disadvantage of direct hydrogenation forming of zirconium materials is that as the hydrogen content increases, material expansion and cracking rapidly increase. This is because during the hydrogenation process of zirconium or zirconium-based alloys, hydrogen molecules enter the interstitial spaces of the zirconium or zirconium-based alloy lattice, causing lattice expansion and resulting in cracks in the material matrix. These cracks significantly reduce the mechanical properties of the zirconium hydride bulk. Most seriously, the newly generated cracks become diffusion channels for the release of hydrogen from the zirconium hydride, leading to a large escape of hydrogen from the zirconium hydride bulk during application.

[0004] Rare earth metals are also excellent hydrogen absorbers, especially since the hydrogen release temperature of some rare earth hydrides is significantly higher than that of zirconium hydride, such as yttrium-doped zirconium hydride. The higher the yttrium content, the higher the phase transition temperature. Yttrium can stabilize hydrogen in zirconium hydride at high temperatures, inhibiting decomposition and hydrogen loss during hydrogenation. However, compared to zirconium, yttrium has a higher ability to stabilize hydrogen, but like zirconium, it lacks neutron absorption properties. Therefore, there is a pressing need to add elements with ultra-high neutron absorption, such as gadolinium (Gd), samarium (Sm), and europium (Eu), to zirconium hydride. The conventional method for adding rare earth nuclides to metallic zirconium is the smelting method. For example, metallic zirconium and a certain proportion of rare earth metals are induction-melted into ingots, which are then further processed into profiles of specific dimensions. These profiles are then placed in a hydrogenation furnace, and by controlling the temperature and hydrogen absorption rate, they are hydrogenated to produce rare earth-doped zirconium hydride blocks. Among rare earth elements with ultra-high neutron absorption, the vapor pressure ranking is Eu > Sm > Gd. Eu and Sm have relatively high vapor pressures, making them unsuitable for electrolytic preparation. They are generally prepared using the principle of high vapor pressure and low vapor pressure of lanthanum through lanthanum thermal reduction distillation. Furthermore, zirconium has a melting point of 1852℃, samarium has a melting point of 1077℃ and a boiling point of 1791℃, and europium has a melting point of 822℃ and a boiling point of 1597℃. Since the melting point of zirconium exceeds the boiling points of samarium and europium, when preparing zirconium alloys containing samarium and / or europium using smelting methods, large amounts of samarium and europium will volatilize into the furnace cavity. The smelting process will result in a very blurred field of vision, making it impossible to judge the melting and casting process. Moreover, samarium and europium dust adheres to the furnace cavity, posing significant safety hazards during furnace opening and dust removal, and the alloy composition is difficult to control precisely. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention involves doping zirconium hydride with at least one of samarium, europium, or gadolinium. All three nuclides exhibit extremely high neutron absorption performance for fast neutrons (energy <1 eV), and their absorption cross-sections in the low-energy range complement each other, significantly improving the material's absorption of low-energy neutrons. Furthermore, by improving the preparation process, including metal hydrogenation powdering, mixing, powder sintering, and secondary hydrogenation, the invention achieves the preparation of bulk zirconium hydride containing samarium, europium, and gadolinium, and precise control of the doping elements.

[0006] One of the objectives of this invention is to provide a zirconium hydride bulk containing samarium / europium / gadolinium.

[0007] The second objective of this invention is to provide a method for preparing the zirconium hydride bulk containing samarium / europium / gadolinium.

[0008] A third objective of this invention is to provide an application of the zirconium hydride bulk containing samarium / europium / gadolinium.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] In a first aspect, the present invention provides a zirconium hydride bulk containing samarium / europium / gadolinium, comprising the following elements by mass percentage: H 1.41~2.11%, Zr+Sm+Eu+Gd≥97.5%, wherein the mass percentage of each element in the total amount of Zr, Sm, Eu and Gd is: 95%≤Zr≤99.5%, 0%≤Gd≤5%, 0%≤Sm≤5%, 0%≤Eu≤ ...Gd≤5%, 0%≤Eu≤5%, 0%≤Sm≤5%, 0%≤Gd≤5%, 0%≤Sm≤5%, 0%≤G <Gd+Sm+Eu≤5%。

[0011] The material of this invention is zirconium hydride doped with samarium / europium / gadolinium. In "samarium / europium / gadolinium," the " / " indicates "and / or," meaning it is doped with at least one of samarium, europium, and gadolinium, and can be any of the following: zirconium hydride doped with samarium, zirconium hydride doped with europium, zirconium hydride doped with gadolinium, zirconium hydride doped with both samarium and europium, zirconium hydride doped with both samarium and gadolinium, zirconium hydride doped with both europium and gadolinium, or zirconium hydride doped with samarium, europium, and gadolinium. The material may also contain unavoidable impurities such as Fe, Cr, O, and C.

[0012] In terms of composition, the zirconium hydride of the present invention is doped with at least one of samarium, europium and gadolinium, which has ultra-high neutron absorption performance, and the absorption cross sections in the low energy range have a complementary effect on each other, which significantly improves the shielding effect after doping.

[0013] Secondly, the present invention provides a method for preparing the above-mentioned samarium / europium / gadolinium-containing zirconium hydride bulk, comprising the following steps:

[0014] (1) Sponge zirconium, metallic gadolinium, metallic europium and metallic samarium were hydrogenated to obtain the corresponding hydride powders;

[0015] (2) Weigh out zirconium hydride, gadolinium hydride, europium hydride and samarium hydride powders according to the required proportions and mix them evenly under a protective atmosphere (such as argon);

[0016] (3) The mixed powder is sintered under pressure and then hydrogenated twice to obtain a zirconium hydride block containing samarium / europium / gadolinium.

[0017] In some implementations, step (1) hydrogenation includes the following steps:

[0018] The metal is placed in a hydrogenation furnace, and a vacuum is drawn until the vacuum level is ≤1.5×10⁻⁶. -2 Pa, the hydrogenation furnace starts heating and continues to be evacuated. When the temperature rises to 280-400℃, the evacuation stops, and high-purity hydrogen gas at a pressure of 0.2-0.5MPa is introduced into the hydrogenation furnace to start absorbing hydrogen until the hydrogen pressure in the hydrogenation furnace no longer drops. Under a protective atmosphere (such as argon), it is crushed into powder with a particle size of less than 150 micrometers for later use.

[0019] In some implementations, step (3) pressure sintering includes one of the following methods:

[0020] Method 1:

[0021] The mixture was loaded into a 30mm diameter graphite mold, with a layer of carbon paper placed between the material and the mold. It was then placed into a hot-press sintering furnace; a vacuum was first applied until the vacuum level was ≤1.5×10⁻⁶. -2 At Pa, heating begins, with a heating rate of 400°C from room temperature to 400°C over 40 minutes, and a pressurization rate of 40 minutes from the initial pressure of 1.5 tons to 2.5 tons. Then, the temperature continues to rise while maintaining a pressure of 2.5 tons, with a heating rate of 10°C / minute, until the temperature reaches 750–900°C. The temperature is held for 90 minutes, and the furnace is allowed to cool naturally to room temperature before being removed from the furnace. The entire process is carried out under vacuum.

[0022] Method 2:

[0023] The mixture was placed into a 30mm diameter cold-press mold, pressurized to 3 tons, and held for 1 minute. After demolding, the block surface was wrapped with three layers of plastic bags, then placed in an isostatic press, pressurized to 200MPa, held for 5 minutes, removed, and the surface plastic bags were peeled off. The block was then placed in a vacuum sintering furnace; a vacuum was first applied until the vacuum degree was ≤1.5×10⁻⁶. -2 When Pa, heating begins. When the temperature reaches 400℃, high-purity argon gas is introduced at a pressure of -0.05MPa. The temperature is increased to 750-900℃ at a rate of 10℃ / min, held for 90 minutes, and then allowed to cool naturally to room temperature before being removed from the furnace. The bulk material is then taken out of the vacuum sintering furnace.

[0024] Method 3:

[0025] The mixture was placed into a 30mm diameter cold-press mold, pressurized to 3 tons, and held for 1 minute. After demolding, the block surface was wrapped with three layers of plastic bags, then placed in an isostatic press, pressurized to 200MPa, held for 5 minutes, removed, and the surface plastic bags were peeled off. The block was then sealed in a quartz tube, and the quartz tube was evacuated to a vacuum degree ≤1.5×10⁻⁶. -2 After Pa, high-purity argon gas is introduced at a pressure of -0.05 MPa; the quartz tube containing the material block is placed in a muffle furnace and heated to 750-900°C at a rate of 10°C / min, held for 90 minutes, and then allowed to cool naturally to room temperature before being removed from the furnace. The quartz tube is then opened to remove the block.

[0026] In some embodiments, step (3) secondary hydrogenation includes the following steps:

[0027] The sintered zirconium hydride block was placed in a hydrogenation furnace and evacuated to a vacuum level ≤1.5×10⁻⁶. -2At a pressure of 0.1 MPa, the hydrogenation furnace is heated and vacuumed. When the temperature rises to 350°C, the vacuuming is stopped. High-purity hydrogen is introduced into the hydrogenation furnace at a pressure of 0.1 MPa and a hydrogen filling rate of 0.00001 × the weight of the placed zirconium hydride block / minute (e.g., if the block weight is in g and the hydrogen filling rate is in g / minute; if the block weight is in kg and the hydrogen filling rate is in kg / minute), until the hydrogen filling flow rate becomes zero. After cooling to room temperature, the hydrogen in the hydrogenation furnace is extracted, and argon gas is introduced. The furnace is then opened and the secondary hydrogenated zirconium hydride block is removed.

[0028] The process of this invention can avoid the volatilization of the components samarium and europium, and can precisely control the ratio of samarium and europium in the zirconium hydride bulk, thus producing rare earth-doped zirconium hydride bulk with uniform composition and precise controllable composition.

[0029] Thirdly, the present invention provides an application of the above-mentioned zirconium hydride bulk containing samarium / europium / gadolinium in the preparation of fast neutron absorbing materials.

[0030] It can be used as a shielding material for small nuclear power reactors below 600℃.

[0031] Beneficial effects:

[0032] 1. In terms of product composition: The zirconium hydride of this invention is doped with at least one of samarium, europium and gadolinium, which has ultra-high neutron absorption performance, and the absorption cross sections in the low energy range have a complementary effect, which significantly improves the shielding effect after doping.

[0033] 2. In terms of preparation process: This invention uses powder sintering to prepare zirconium hydride with the addition of high vapor pressure elements samarium and europium. These two elements have high vapor pressures, making it difficult to control their proportion in the alloy using conventional smelting methods. Furthermore, during production, samarium and europium volatilize and form white fumes in the vacuum furnace, making it impossible for operators to observe the molten liquid surface, which is extremely dangerous. The powder sintering process overcomes these drawbacks of the smelting method.

[0034] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Detailed Implementation

[0035] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0036] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0037] Zirconium sponge, gadolinium metal, europium metal, and samarium metal are all commercially available.

[0038] Preparation of zirconium hydride, gadolinium hydride, europium hydride, and samarium hydride powders

[0039] The sponge zirconium was placed in a hydrogenation furnace and evacuated to a vacuum level ≤1.5×10⁻⁶. -2 At a pressure of Pa, the hydrogenation furnace begins heating and continues to be evacuated. When the temperature rises to 400℃, the evacuation is stopped, and high-purity hydrogen gas at a pressure of 0.4 MPa is introduced into the hydrogenation furnace. The sponge zirconium begins to absorb hydrogen until it is fully saturated and the hydrogen pressure inside the furnace no longer decreases. The zirconium is then converted into zirconium hydride. The zirconium hydride is then crushed into powder with a particle size of less than 150 micrometers under argon gas for later use.

[0040] Metallic gadolinium is placed in a hydrogenation furnace, and a vacuum is drawn until the vacuum level is ≤1.5×10⁻⁶. -2 At a pressure of Pa, the hydrogenation furnace begins heating and continues to be evacuated. When the temperature rises to 300℃, the evacuation is stopped, and high-purity hydrogen gas at a pressure of 0.5 MPa is introduced into the hydrogenation furnace. Metallic gadolinium begins to absorb hydrogen until it is fully saturated and the hydrogen pressure inside the furnace no longer decreases. At this point, gadolinium is converted into gadolinium hydride. The gadolinium hydride is then crushed into powder with a particle size of less than 150 micrometers under argon gas for later use.

[0041] Metallic samarium is placed in a hydrogenation furnace, and a vacuum is drawn until the vacuum level is ≤1.5×10⁻⁶. -2 At a pressure of Pa, the hydrogenation furnace begins heating and continues to be evacuated. When the temperature rises to 300℃, the evacuation is stopped, and high-purity hydrogen gas at a pressure of 0.2 MPa is introduced into the hydrogenation furnace. Metallic samarium begins to absorb hydrogen until it is fully saturated and the hydrogen pressure inside the furnace no longer decreases. At this point, the samarium is converted into samarium hydride. The samarium hydride is then crushed into powder with a particle size of less than 150 micrometers under argon gas for later use.

[0042] Europium metal was placed in a hydrogenation furnace and evacuated to a vacuum level ≤1.5×10⁻⁶. -2 At a pressure of Pa, the hydrogenation furnace begins heating and continues to be evacuated. When the temperature rises to 280℃, the evacuation is stopped, and high-purity hydrogen gas at a pressure of 0.2 MPa is introduced into the hydrogenation furnace. Europium metal begins to absorb hydrogen until it is fully saturated and the hydrogen pressure inside the furnace no longer decreases. At this point, europium is transformed into europium hydride. The europium hydride is then crushed into powder with a particle size of less than 150 micrometers under argon gas for later use.

[0043] Composition Design of Examples 1-9

[0044] Weigh the corresponding weights of zirconium hydride, samarium hydride, europium hydride, and gadolinium hydride according to the mass ratios listed in Table 1, mix them evenly under argon atmosphere, and set aside for later use.

[0045] Table 1 Design values ​​of elemental composition for zirconium hydride bulk

[0046]

[0047] Preparation process of Examples 1-9

[0048] Preparation in Example 1:

[0049] Sintering: Mixture No. 1 is loaded into a 30mm diameter graphite mold (30mm high), with a layer of carbon paper between the material and the mold to prevent the rare earth elements in the material from reacting with the mold. Then it is placed into a hot-press sintering furnace; a vacuum is first applied until the vacuum degree is ≤1.5×10⁻⁶. -2 Pa, start heating, heating rate from room temperature to 400℃ in 40 minutes, pressurization rate from initial pressure 1.5 tons to 2.5 tons in 40 minutes; then continue heating and maintain 2.5 tons pressure, heating rate 10℃ / min, heating to 750℃, hold at 750℃ for 90 minutes, then let it cool naturally to room temperature and remove from the furnace, with vacuum throughout the process.

[0050] Secondary hydrogenation: The sintered bulk material is placed in a hydrogenation furnace and evacuated to a vacuum level ≤1.5×10⁻⁶. -2 At a pressure of Pa, the hydrogenation furnace begins heating and continues to be evacuated. When the temperature rises to 350℃, the evacuation is stopped, and high-purity hydrogen gas at a pressure of 0.1 MPa is introduced into the hydrogenation furnace. Based on a 40g block, the hydrogen charging rate is... 40g / min = 0.0004g / min hydrogen charging, the block begins to absorb hydrogen until the hydrogen charging flow rate becomes zero; cool to room temperature, extract the hydrogen from the hydrogenation furnace and introduce argon gas, open the furnace and take out the hydrogenated zirconium block that has undergone secondary hydrogenation.

[0051] Preparation in Example 2:

[0052] Sintering: The No. 2 mixture is loaded into a 30mm diameter graphite mold (30mm high), with a layer of carbon paper between the material and the mold to prevent the rare earth elements in the material from reacting with the mold. Then it is placed into a hot-press sintering furnace; a vacuum is first applied until the vacuum degree is ≤1.5×10⁻⁶. -2 Pa, start heating, heating rate from room temperature to 400℃ in 40 minutes, pressurization rate from initial pressure 1.5 tons to 2.5 tons in 40 minutes; then continue heating and maintain 2.5 tons pressure, heating rate 10℃ / min, heating to 800℃, holding at 800℃ for 90 minutes, then naturally cooling to room temperature in the furnace before being removed from the furnace, with vacuum throughout the process.

[0053] The secondary hydrogenation is the same as in Example 1.

[0054] Preparation in Example 3:

[0055] Sintering: Mixture No. 3 is loaded into a 30mm diameter graphite mold (30mm high), with a layer of carbon paper between the material and the mold to prevent the rare earth elements in the material from reacting with the mold. Then it is placed into a hot-press sintering furnace; a vacuum is first applied until the vacuum degree is ≤1.5×10⁻⁶. -2 Pa, start heating, heating rate from room temperature to 400℃ in 40 minutes, pressurization rate from initial pressure 1.5 tons to 2.5 tons in 40 minutes; then continue heating and maintain 2.5 tons pressure, heating rate 10℃ / min, heating to 820℃, hold at 820℃ for 90 minutes, then let it cool naturally to room temperature and remove from the furnace, with vacuum throughout the process.

[0056] The secondary hydrogenation is the same as in Example 1.

[0057] Preparation in Example 4:

[0058] Sintering: Mixture No. 4 is loaded into a 30mm diameter graphite mold (30mm high). A layer of carbon paper is placed between the material and the graphite mold to prevent the rare earth elements in the material from reacting with the mold, thus reducing the rare earth content in the zirconium hydride block. Then, it is placed into a hot-press sintering furnace. A vacuum is first applied, and the vacuum degree is ≤1.5×10⁻⁶. -2 Pa, start heating, heating rate from room temperature to 400℃ in 40 minutes, pressurization rate from initial pressure 1.5 tons to 2.5 tons in 40 minutes; then continue heating and maintain 2.5 tons pressure, heating rate 10℃ / min, heating to 800℃, holding at 800℃ for 90 minutes, then naturally cooling to room temperature in the furnace before being removed from the furnace, with vacuum throughout the process.

[0059] The secondary hydrogenation is the same as in Example 1.

[0060] Preparation in Example 5:

[0061] Sintering: Mixture No. 5 is loaded into a 30mm diameter graphite mold (30mm high), with a layer of carbon paper between the material and the mold to prevent the rare earth elements in the material from reacting with the mold. Then it is placed into a hot-press sintering furnace; a vacuum is first applied until the vacuum degree is ≤1.5×10⁻⁶. -2 Pa, start heating, heating rate from room temperature to 400℃ in 40 minutes, pressurization rate from initial pressure 1.5 tons to 2.5 tons in 40 minutes; then continue heating and maintain 2.5 tons pressure, heating rate 10℃ / min, heating to 850℃, holding at 850℃ for 90 minutes, then naturally cooling to room temperature in the furnace before being removed from the furnace, with vacuum throughout the process.

[0062] The secondary hydrogenation is the same as in Example 1.

[0063] Preparation in Example 6:

[0064] Sintering: Mixture No. 6 is loaded into a 30mm diameter graphite mold (30mm high), with a layer of carbon paper between the material and the mold to prevent the rare earth elements in the material from reacting with the mold. Then it is placed into a hot-press sintering furnace; a vacuum is first applied until the vacuum degree is ≤1.5×10⁻⁶. -2 Pa, start heating, heating rate from room temperature to 400℃ in 40 minutes, pressurization rate from initial pressure 1.5 tons to 2.5 tons in 40 minutes; then continue heating and maintain 2.5 tons pressure, heating rate 10℃ / min, heating to 900℃, hold at 90 minutes, and then let it cool naturally to room temperature before being removed from the furnace, with vacuum throughout the process.

[0065] The secondary hydrogenation is the same as in Example 1.

[0066] Preparation in Example 7:

[0067] Sintering: The No. 7 mixture is loaded into a cold-press mold with a diameter of 30 mm (filling height of 30 mm), pressurized to 3 tons and held for 1 minute; after demolding, the surface of the block is wrapped with 3 layers of plastic bags, and then placed in an isostatic press, pressurized to 200 MPa, held for 5 minutes, and then the plastic bags on the surface are removed and sealed in a quartz tube. The quartz tube is evacuated and filled with high-purity argon gas at a pressure of -0.05 MPa; the quartz tube containing the block is placed in a muffle furnace, heated to 850°C at 10°C / min, held for 90 minutes, and then cooled naturally to room temperature in the furnace before being removed from the furnace. The block is then taken out by opening the quartz tube.

[0068] The secondary hydrogenation is the same as in Example 1.

[0069] Preparation in Example 8:

[0070] Sintering: The No. 8 mixture is loaded into a cold-press mold with a diameter of 30 mm (filling height of 30 mm), pressurized to 3 tons and held for 1 minute; after demolding, the surface of the block is wrapped with 3 layers of plastic bags, and then placed in an isostatic press, pressurized to 200 MPa, held for 5 minutes, and then the plastic bags on the surface are removed and sealed in a quartz tube. The quartz tube is evacuated and filled with high-purity argon gas at a pressure of -0.05 MPa; the quartz tube containing the block is placed in a muffle furnace, heated to 900℃ at 10℃ / min, held for 90 minutes, and then cooled naturally to room temperature in the furnace before being removed from the furnace. The block is then taken out by opening the quartz tube.

[0071] The secondary hydrogenation is the same as in Example 1.

[0072] Preparation in Example 9:

[0073] Sintering: The No. 9 mixture is loaded into a cold-press mold with a diameter of 30 mm (filling height of 30 mm), pressurized to 3 tons and held for 1 minute; after demolding, the surface of the block is wrapped with 3 layers of plastic bags, and then placed in an isostatic press, pressurized to 200 MPa, held for 5 minutes, and then the plastic bags on the surface are removed and sealed in a quartz tube. The quartz tube is evacuated and filled with high-purity argon gas at a pressure of -0.05 MPa; the quartz tube containing the block is placed in a muffle furnace, heated to 850°C at 10°C / min, held for 90 minutes, and then cooled naturally to room temperature in the furnace before being removed from the furnace. The block is then taken out by opening the quartz tube.

[0074] The secondary hydrogenation is the same as in Example 1.

[0075] Preparation of bulk zirconium hydride as a control example:

[0076] Zirconium hydride powder was directly loaded into a 30mm diameter graphite mold (30mm high). A layer of carbon paper was placed between the material and the graphite mold to prevent the rare earth elements in the material from reacting with the mold. The mold was then placed into a hot-pressing sintering furnace. A vacuum was first applied, and the vacuum level was ≤1.5×10⁻⁶. -2 Pa, start heating, heating rate from room temperature to 400℃ in 40 minutes, pressurization rate from initial pressure 1.5 tons to 2.5 tons in 40 minutes; then continue heating and maintain 2.5 tons pressure, heating rate 10℃ / min, heating to 750℃, hold at 750℃ for 90 minutes, then let it cool naturally to room temperature and remove from the furnace, with vacuum throughout the process.

[0077] Test Example 1

[0078] Fast neutron absorption efficiency tests were performed on the samarium / europium / gadolinium-containing zirconium bulk materials prepared in Examples 1-9, the undoped zirconium bulk material prepared in the control example, and metallic gadolinium.

[0079] Fast neutron absorption efficiency testing method: MCNP calculation software based on the Monte Carlo method was used to conduct fast neutron absorption calculations on a 15cm thick layer at 2MeV, with the number of neutrons set to 10-1. 7 .

[0080] The results are shown in Table 2.

[0081] Table 2

[0082]

[0083] It can be seen that the shielding absorption efficiency of zirconium hydride bulk is around 82%. Gadolinium itself has poor absorption of fast neutrons, with only 30%. However, after incorporating gadolinium into zirconium hydride to prepare zirconium hydride bulk containing gadolinium and other elements, the shielding performance is significantly improved, reaching over 91% (the fast neutron absorption rate of zirconium hydride bulk with added rare earth elements > zirconium hydride fast neutron absorption rate × zirconium hydride proportion + rare earth element fast neutron absorption rate × rare earth element proportion). This produced a synergistic effect.

[0084] Test Example 2

[0085] The zirconium hydride blocks containing samarium / europium / gadolinium prepared by the sintering method according to the examples were subjected to compositional analysis (GB / T13747 Chemical Analysis Methods for Zirconium and Zirconium Alloys; GB / T 14635 Chemical Analysis Methods for Rare Earth Metals and Their Compounds - Determination of Total Rare Earth Content) and the results are shown in Tables 3 and 4.

[0086] Zirconium hydride ingots containing samarium / europium / gadolinium were prepared by smelting: Sponge zirconium, metallic gadolinium, metallic europium, and metallic samarium were weighed according to the proportions listed in Table 1 and placed in a vacuum medium-frequency induction melting furnace to melt and cast into ingots. After cooling to room temperature, the ingots were removed and processed into profiles of a specific size. These profiles were then placed in a hydrogenation furnace, which was evacuated to a vacuum level ≤1.5 × 10⁻⁶. -2 At a pressure of Pa, the hydrogenation furnace begins heating and continues to be evacuated. When the temperature rises to 400℃, the evacuation is stopped, and high-purity hydrogen gas at a pressure of 0.1 MPa is introduced into the hydrogenation furnace. Based on a 40g block, the hydrogen charging rate is... 40g / min = 0.0004g / min hydrogen charging, the block begins to absorb hydrogen until the hydrogen charging flow rate becomes zero, naturally cools to room temperature, extracts the hydrogen from the hydrogenation furnace, introduces argon gas, opens the furnace and takes out the hydrogenated block for relevant tests.

[0087] Table 3. Element content of bulk materials prepared by sintering method

[0088]

[0089] Table 4. Element content of bulk materials prepared by smelting method

[0090]

[0091] The results showed that the alloys with the compositions of Examples 1-9 were prepared by melting and their compositions were analyzed. However, due to the high vapor pressures of samarium and europium, especially europium, a large amount of samarium and europium volatilized during the melting process, making it impossible to control the accuracy of the final alloy composition.

[0092] The purpose of secondary hydrogenation is to ensure the hydrogen content, which affects the overall performance of the bulk material. This invention's preparation process actually includes two aspects: 1. Direct hot pressing into zirconium hydride bulk materials. However, hydrogen is lost during the hot pressing process, and these bulk materials can still be used in applications with low performance requirements. 2. To pursue higher performance, further improvements are made by secondary hydrogenation, which compensates for the hydrogen loss during hot pressing and sintering, thus improving its performance.

[0093] 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 method for producing a bulk zirconium hydride containing samarium / europium / gadolinium, characterized by, The zirconium hydride bulk containing samarium / europium / gadolinium comprises the following mass percentages of elements: H 2.07-2.11%, Zr+Sm+Eu+Gd≥97.5%, wherein the mass percentages of each element in the total amount of Zr, Sm, Eu and Gd elements are: 95%≤Zr≤99.5%, 0%<Gd<5%, 0%<Sm<5%, 0%<Eu<5%, 0%<Gd+Sm+Eu≤5%; The preparation method of the zirconium hydride bulk containing samarium / europium / gadolinium comprises the following steps: (1) hydrogenating sponge zirconium, metal gadolinium, metal europium and metal samarium respectively to obtain corresponding hydride powders; (2) weighing the zirconium hydride, gadolinium hydride, europium hydride and samarium hydride powders according to the required proportions and mixing them uniformly under a protective atmosphere; (3) pressure sintering the mixed powders and performing secondary hydrogenation to obtain the zirconium hydride bulk containing samarium / europium / gadolinium; The pressure sintering of step (3) is as follows: The mixture was loaded into a 30 mm diameter cold-pressing mold, pressed to 3 tons and kept for 1 minute; after demolding, the surface of the block was wrapped with 3 layers of plastic bags, then it was put into an isostatic press, pressed to 200 MPa, kept for 5 minutes, then taken out and the surface plastic bags were peeled off, then it was packaged into a quartz tube, the quartz tube was vacuumized to a vacuum degree of ≤1.5×10 -2 Pa, then high-purity argon was filled, the pressure was -0.05 MPa; the quartz tube with the packaged block was put into a muffle furnace, heated to 750-900℃ at a rate of 10℃ / minute, kept for 90 minutes, naturally cooled to room temperature with the furnace, taken out of the furnace, the quartz tube was opened and the block was taken out.

2. The production method according to claim 1, characterized by, The hydrogenation of step (1) comprises the following steps: Put the metal into the hydrogenation furnace, vacuumize to vacuum degree ≤ 1.5 x 10 -2 Pa, the hydrogenation furnace starts to heat and continues to vacuumize, when the temperature rises to 280-400℃, stop vacuumizing, introduce high purity hydrogen gas with pressure of 0.2-0.5 MPa into the hydrogenation furnace, start to absorb hydrogen, until the hydrogen pressure in the hydrogenation furnace no longer decreases, under the protection of atmosphere, crush into powder with particle size below 150 microns for use.

3. The preparation method according to claim 2, characterized in that, The secondary hydrogenation of step (3) comprises the following steps: The sintered zirconium hydride block is put into a hydrogenation furnace, vacuumed to a vacuum degree of ≤1.5×10 -2 Pa, and heated to continue vacuuming. When the temperature rises to 350℃, the vacuuming is stopped. High-purity hydrogen with a pressure of 0.1 MPa and a hydrogenation speed of 0.00001×the weight of the zirconium hydride block put in / minute is introduced into the hydrogenation furnace until the hydrogenation flow becomes zero. After cooling to room temperature, the hydrogen in the hydrogenation furnace is pumped out and argon is introduced. The zirconium hydride block after secondary hydrogenation is taken out.

4. Application of the zirconium hydride bulk containing samarium / europium / gadolinium prepared by the preparation method of any one of claims 1-3 in preparation of fast neutron absorbing materials.

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