A hydrogen barrier coating on the surface of a metal hydride material and a method of making and using the same

Abstract

The application discloses a hydrogen barrier coating on a surface of a metal hydride material and a preparation method and application thereof, and belongs to the technical field of nuclear reactor control materials. The preparation method comprises the following steps: performing pretreatment on the surface of a metal hydride base; and forming the hydrogen barrier coating of at least one of an erbium oxide coating, an aluminum oxide coating and a mixed layer of the erbium oxide and the aluminum oxide on the metal hydride base by adopting a sol-gel method and / or a thermal spraying method. The hydrogen barrier coating on the surface of the metal hydride material provided by the application is different from the traditional mode of mixing the erbium oxide into a nuclear fuel pellet and placing the hydrogen barrier coating on the surface of a cladding, the application places the erbium in the form of the erbium oxide hydrogen barrier coating on the surface of the metal hydride, simultaneously adds or adjusts the content of the aluminum oxide to meet the demand of the hydrogen barrier performance, forms the metal hydride moderating material containing the hydrogen barrier coating, and can simultaneously realize the purposes of the continuous high-temperature moderating capability of the metal hydride moderating material and the reactivity control.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor control materials technology, specifically to a hydrogen barrier coating on the surface of a metal hydride material, its preparation method, and its application. Background Technology

[0002] Fourth-generation nuclear power technology and various flexible, safe, and efficient multi-purpose reactor technologies are advancing rapidly. The traditional approach of using high-temperature, high-pressure water as a neutron moderator can no longer meet the high-temperature and compact design requirements of new nuclear power reactors. Metal hydrides, especially zirconium hydride and yttrium hydride, have the same or even higher hydrogen atom concentrations than pure water and liquid hydrogen, resulting in superior moderation performance. They also offer advantages such as higher operating temperatures, smaller size, and more flexible core arrangement, making them a key research focus for new high-temperature moderator materials and holding immense application potential in future advanced nuclear power reactor technologies.

[0003] Even metal hydrides with high-temperature stability will gradually release hydrogen during long-term high-temperature service. In an atmosphere with a hydrogen partial pressure of 1 atm, zirconium hydride begins to decompose rapidly at around 800°C, while yttrium hydride gradually releases hydrogen above 800°C, with the release rate accelerating at around 1000°C. The decrease in hydrogen content weakens the neutron moderation ability of moderator materials, reducing neutron economy. Furthermore, the released hydrogen can spread into the reactor, causing hydrogen embrittlement of the structural metal materials and posing a significant safety hazard to reactors operating at high temperatures, due to its flammable and explosive nature. Therefore, improving the hydrogen storage performance of metal moderator materials has become a key focus of advanced moderator material research. Summary of the Invention

[0004] The purpose of this invention is to provide a hydrogen-blocking coating for the surface of metal hydride materials, its preparation method, and its application. This invention solves the problem that metal hydrides gradually release hydrogen during long-term high-temperature service, leading to a weakening of the neutron moderation ability of the moderator material and hydrogen embrittlement of the structural metal material, which poses a safety hazard to the reactor.

[0005] This invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing a hydrogen-barrier coating on the surface of a metal hydride material, comprising:

[0007] Surface pretreatment of the metal hydride matrix;

[0008] Hydrogen-barrier coatings are formed on a metal hydride substrate using a sol-gel method and / or thermal spraying method, comprising at least one of erbium oxide coating, aluminum oxide coating, and a mixed layer of erbium oxide and aluminum oxide.

[0009] Furthermore, in the method for preparing the hydrogen-barrier coating on the surface of the metal hydride material, the metal hydride includes: zirconium hydride, yttrium hydride, uranium-doped zirconium hydride, or uranium-doped yttrium hydride.

[0010] Furthermore, in the method for preparing the hydrogen-barrier coating on the surface of the metal hydride material, the sol-gel method used to prepare the erbium oxide coating specifically includes:

[0011] Erbium-containing salts were dissolved in collodion to prepare a sol-gel solution with a concentration of 1-5 mol / L.

[0012] The metal hydride matrix is ​​immersed in a sol-gel solution, and the immersed metal hydride matrix is ​​repeatedly lifted from the sol-gel solution at a lifting speed of 10-100 mm / min at least 10 times using the lifting method.

[0013] After removing the moisture adhering to the metal hydride matrix by drying at room temperature, the sol-gel solution is dehydrated at high temperature.

[0014] Preferably, the erbium-containing salt includes one or more of erbium nitrate, erbium carbonate, erbium phosphate, and erbium sulfate.

[0015] Furthermore, in the method for preparing the hydrogen-barrier coating on the surface of the metal hydride material, the sol-gel method for preparing the alumina coating specifically includes:

[0016] Aluminum alkoxide is added to water, heated and stirred for 20 minutes to dissolve, then an inorganic acid is added and hydrolyzed at 85-95℃ with stirring for 3-5 hours. After that, it is kept at 95-120℃ for 20-40 hours to obtain a clear and transparent Al2O3 sol.

[0017] The metal hydride matrix was immersed in Al2O3 sol, and the immersed metal hydride matrix was pulled out of Al2O3 sol at a pulling speed of 10-100 mm / min using the dip-coating method.

[0018] After removing the moisture adhering to the metal hydride matrix by drying at room temperature, the sol-gel solution is dehydrated at high temperature.

[0019] Preferably, the aluminum alkoxide comprises one or more of aluminum isopropoxide, aluminum propoxide, aluminum ethoxide, and aluminum n-butoxide.

[0020] Furthermore, in the method for preparing the hydrogen-barrier coating on the surface of the metal hydride material, the high-temperature dehydration step includes:

[0021] Heat to 100-300℃ at a heating rate of 2-5℃ / min, and hold at that temperature for 20-50min.

[0022] Heat to 400-700℃ at a heating rate of 5-7℃ / min, and hold for 20-40 minutes.

[0023] Furthermore, in the method for preparing the hydrogen-barrier coating on the surface of the metal hydride material, the thermal spraying method used to prepare the hydrogen-barrier coating specifically includes:

[0024] Take Al₂O₃ and / or Er₂O₃ powder with a particle size of 1-5 μm, spray at a distance of 150-200 mm, and use an acetylene volumetric flow rate of 1-3 m³ / h. 3 / h, oxygen volumetric flow rate 1-4m³ 3 / h, nitrogen volumetric flow rate 0.1-1m³ 3 / h, explosion frequency 2-10 times / s, linear velocity 400-600mm / min, powder conveying mass flow rate 20-30g / min, spraying time 5-20min, followed by polishing.

[0025] The present invention also provides a hydrogen barrier coating on the surface of a metal hydride material prepared by the above preparation method, wherein the hydrogen barrier coating on the surface of the metal hydride material includes at least one of: erbium oxide coating, aluminum oxide coating, and a mixed layer of erbium oxide and aluminum oxide.

[0026] Furthermore, in the hydrogen barrier coating on the surface of the metal hydride material, the thickness of the hydrogen barrier coating on the surface of the metal hydride material is 2-5 μm.

[0027] Furthermore, in the hydrogen barrier coating on the surface of the metal hydride material, when the hydrogen barrier coating on the surface of the metal hydride material includes: an erbium oxide coating and an aluminum oxide coating, the erbium oxide coating and the aluminum oxide coating are uniformly and / or have a gradient distribution.

[0028] The present invention also provides the application of the above-mentioned hydrogen barrier coating on the surface of metal hydride materials in nuclear reactors.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] The hydrogen-barrier coating on the surface of metal hydride materials provided by this invention is based on a comprehensive consideration of the dual requirements of new nuclear power reactors for maintaining the high-temperature stability of metal hydride moderator materials and compensating for residual reactivity. Unlike the traditional method of incorporating erbium oxide into nuclear fuel pellets and placing the hydrogen-barrier coating on the cladding surface, this invention places erbium on the surface of the metal hydride as an erbium oxide hydrogen-barrier coating, while adding or adjusting the content of alumina to meet the requirements of hydrogen-barrier performance, forming a metal hydride moderator material with a hydrogen-barrier coating. This simultaneously achieves the purpose of continuous high-temperature moderation capability and reactivity control of the metal hydride moderator material.

[0031] This invention prepares a hydrogen-blocking coating containing the combustible poison erbium on the surface of a metal hydride moderator material, which can simultaneously achieve continuous stability of the moderation capability and compensated control of reactor reactivity, and avoids the need for additional combustible poison placement, thereby improving the compactness of the nuclear power reactor. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0033] Figure 1 The surface morphology of a single erbium oxide coating prepared by the sol-gel method in Example 1 of this invention;

[0034] Figure 2 The image shows the cross-sectional morphology of a single erbium oxide coating prepared by the sol-gel method in Example 1 of this invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0036] The technical solution of this invention is as follows:

[0037] A method for preparing a hydrogen-barrier coating on the surface of a metal hydride material, comprising:

[0038] Surface pretreatment of the metal hydride matrix;

[0039] Hydrogen-barrier coatings are formed on a metal hydride substrate using a sol-gel method and / or thermal spraying method, comprising at least one of erbium oxide coating, aluminum oxide coating, and a mixed layer of erbium oxide and aluminum oxide.

[0040] In new nuclear power reactors, the initial residual reactivity of newly loaded fuel is relatively high. Besides using control rods, combustible poisons are typically used to compensate for this residual reactivity. Erbium (Er) is one of the combustible poison materials in light water reactors. Natural erbium contains six isotopes: 163 Er (0.14%) 164 Er (1.61%) 166 Er (33.6%)167 Er (22.95%) 168 Er (26.8%) and 170 Er (14.9%), the main absorber is 167 Er, whose thermal neutron absorption cross section is 740 target, and 166 Er will transform into... after absorbing neutrons. 167 Erbium, compared to the commonly used combustible poison gadolinium, is consumed more slowly, making it more suitable for long-life refueling designs. In international thermonuclear fusion reactors, erbium oxide is widely used as a hydrogen barrier coating due to its high thermal stability, resistance to oxidation, high insulation, and effective inhibition of hydrogen isotope permeation. Therefore, erbium oxide can serve a dual role in nuclear power reactors as both a neutron-burning poison and a hydrogen barrier coating.

[0041] Alumina has a low neutron absorption cross section and better hydrogen barrier properties than erbium oxide. Depending on the required compensation for residual reactivity, the erbium oxide content or thickness can be adjusted, while simultaneously adding or adjusting the alumina content to meet the hydrogen barrier performance requirements.

[0042] Zirconium hydride and yttrium hydride possess excellent high-temperature hydrogen storage performance, but when the hydrogen bias voltage in a high-temperature environment is lower than their equilibrium pressure, hydrogen is slowly released, and their neutron moderation performance decreases accordingly. The hydrogen-blocking coating on the surface of the metal hydride material provided by this invention uses erbium oxide as the main coating material, fully leveraging its dual role as a neutron poison and hydrogen-blocking coating. Furthermore, alumina, with its lower neutron absorption cross-section and better hydrogen-blocking performance, is considered as a supplementary hydrogen-blocking material to further improve the coating's hydrogen-blocking performance. The preparation method of this invention changes the traditional method of placing the hydrogen-blocking coating on the cladding wall, directly controlling hydrogen within the moderated pellet, thereby reducing the risk of hydrogen embrittlement of the cladding material. It also changes the traditional method of combining neutron combustible poison with fuel or separately setting combustible poison rods to a method of using a hydrogen-blocking coating on the moderated pellet, which not only reduces the preparation difficulty but also improves the compactness of the reactor core. Therefore, using this invention, the goal of continuous high-temperature moderation and reactivity control of metal hydride moderators can be achieved simultaneously.

[0043] The hydrogen-barrier coating on the surface of metal hydride materials provided by this invention is based on a comprehensive consideration of the dual requirements of new nuclear power reactors for maintaining the high-temperature stability of metal hydride moderator materials and compensating for residual reactivity. Unlike the traditional method of incorporating erbium oxide into nuclear fuel pellets and placing the hydrogen-barrier coating on the cladding surface, this invention places erbium on the surface of the metal hydride as an erbium oxide hydrogen-barrier coating, while adding or adjusting the content of alumina to meet the requirements of hydrogen-barrier performance, forming a metal hydride moderator material with a hydrogen-barrier coating. This simultaneously achieves the purpose of continuous high-temperature moderation capability and reactivity control of the metal hydride moderator material.

[0044] This invention prepares a hydrogen-blocking coating containing the combustible poison erbium on the surface of a metal hydride moderator material, which can simultaneously achieve continuous stability of the moderation capability and compensated control of reactor reactivity, and avoids the need for additional combustible poison placement, thereby improving the compactness of the nuclear power reactor.

[0045] The hydrogen-blocking coating on the surface of a metal hydride material provided by this invention includes at least one of erbium oxide coating, aluminum oxide coating, and a mixed layer of erbium oxide and aluminum oxide. Erbium oxide has the dual functions of residual reactivity control and hydrogen-blocking capability, but its hydrogen-blocking performance is inferior to that of aluminum oxide, which only has hydrogen-blocking capability. Therefore, this invention comprehensively considers the dual requirements of new nuclear power reactors for maintaining the high-temperature stability of metal hydride moderator materials and controlling residual reactivity compensation. Erbium is placed on the surface of the metal hydride as an erbium oxide hydrogen-blocking coating, while the content of aluminum oxide is added or adjusted to meet the hydrogen-blocking performance requirements, forming a metal hydride moderator material with a hydrogen-blocking coating. This simultaneously achieves the purpose of continuous high-temperature moderation capability and reactivity control of the metal hydride moderator material. The composition of the hydrogen-blocking coating on the surface of the metal hydride material is selected to meet the requirements, specifically as follows:

[0046] If the requirements for reactivity control and hydrogen barrier capability can be met simultaneously by using only an erbium oxide layer, then the hydrogen barrier coating on the surface of the metal hydride material is a single erbium oxide coating.

[0047] If the hydrogen barrier capability is insufficient after meeting the reactivity control requirements, a composite coating of erbium oxide and alumina layers can be used on the surface of the metal hydride material. This composite coating can be designed with an inner erbium oxide layer and an outer alumina layer, an inner alumina layer and an outer erbium oxide layer, or a structure where erbium oxide and alumina are either uniform or gradient, depending on the required distance between the erbium oxide and the center of the metal hydride. For the two types of coatings—erbium oxide inner layer and alumina outer layer, and alumina inner layer and erbium oxide outer layer—the inner layer uses the sol-gel method, while the outer layer can use either the sol-gel method or thermal spraying. When preparing a coating with a uniform or gradient structure of erbium oxide and alumina, a single alumina or erbium oxide coating is first pre-formed on the metal hydride surface using the sol-gel method, followed by thermal spraying to complete the subsequent coating processing.

[0048] If there is no need for residual reactivity control, the hydrogen barrier coating on the surface of the metal hydride material is a single alumina coating.

[0049] In this invention, the control of residual reactivity and the adjustment of hydrogen barrier capacity can be achieved not only by adjusting the structure of the erbium oxide layer and the aluminum oxide layer, but also by adjusting the thickness of the coating, which can also meet the requirements.

[0050] To further illustrate the present invention, the following description, in conjunction with embodiments, describes the hydrogen-barrier coating on the surface of the metal hydride material provided by the present invention. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating procedures. They are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0051] Example 1

[0052] In this embodiment, the hydrogen-barrier coating on the surface of the metal hydride material was prepared using the sol-gel method to prepare an Er2O3 hydrogen-barrier coating on the surface of zirconium hydride. The specific steps are as follows:

[0053] (1) Surface pretreatment of zirconium hydride blocks to remove surface impurities and improve the adhesion of coatings to zirconium hydride surfaces;

[0054] (2) The zirconium hydride block obtained in step (1) is ultrasonically cleaned to remove contaminants from the surface of the block;

[0055] (3) Preparation of erbium oxide precursor solution: A mixed solution of erbium nitrate and collodion was used as the sol-gel solution, wherein the concentration of erbium nitrate was 1 mol / L and the volume percentage of collodion was 10%.

[0056] (4) Using the lifting method, place the zirconium hydride block cleaned in step (2) into the sol-gel solution prepared in step (3) and soak for 5 minutes;

[0057] (5) Pull the block soaked in step (4) out of the sol-gel liquid at a uniform speed of 100 mm / min.

[0058] (6) Dry the sample from step (5) at room temperature for 20 minutes to remove moisture from the sol;

[0059] (7) Place the dried gel from step (6) in a muffle furnace and heat it to 200°C at a rate of 2°C / min, while holding it at that temperature for 30 minutes to further remove moisture from the gel. Then heat it to 500°C at a rate of 5°C / min and hold it at that temperature for 20 minutes. After holding at that temperature, allow it to cool naturally to room temperature with the furnace.

[0060] (8) After repeating steps (4) to (7) a total of 10 times, the coating thickness is about 2 μm.

[0061] The composition and microstructure of the coated zirconium hydride sample were analyzed by XRD and SEM using the coating prepared in step (8). (See attached image.) Figure 1 The results showed that the Er2O3 coating prepared on the zirconium hydride surface was composed of a single Er2O3 component and had a dense structure without cracks.

[0062] Example 2

[0063] In this embodiment, the hydrogen-barrier coating on the surface of the metal hydride material was prepared using the sol-gel method to prepare an Al2O3 hydrogen-barrier coating on the surface of zirconium hydride. The specific steps are as follows:

[0064] (1) Surface pretreatment of zirconium hydride blocks to remove surface impurities and improve the adhesion of coatings to zirconium hydride surfaces;

[0065] (2) The zirconium hydride block obtained in step (1) is ultrasonically cleaned to remove contaminants from the surface of the block;

[0066] (3) Preparation of alumina precursor solution: Aluminum isopropoxide reacts with water under certain conditions to undergo hydrolysis, and the product further undergoes dehydration condensation or de-alcoholization condensation reaction to generate Al2O3 sol mainly composed of Al-O bonds. The steps are as follows: Aluminum isopropoxide is added to an appropriate amount of hot water, heated and stirred for 20 min, and then an appropriate amount of hydrolysis catalyst---acid is added; the temperature is maintained above 85℃ and stirred for 3 h; after maintaining the temperature above 95℃ for 24 h, a clear and transparent Al2O3 sol is obtained;

[0067] (4) Using the lifting method, place the zirconium hydride block cleaned in step (2) into the sol-gel solution prepared in step (3) and soak for 5 minutes;

[0068] (5) Pull the block soaked in step (4) out of the sol-gel liquid at a uniform speed of 100 mm / min.

[0069] (6) Dry the sample from step (5) at room temperature for 20 minutes to remove moisture from the sol;

[0070] (7) Place the dried gel from step (6) in a muffle furnace and heat it to 200°C at a rate of 2°C / min, while holding it at that temperature for 30 minutes to further remove moisture from the gel. Then heat it to 600°C at a rate of 5°C / min and hold it at that temperature for 20 minutes. After holding at that temperature, allow it to cool naturally to room temperature with the furnace.

[0071] (8) After repeating steps (4) to (7) a total of 10 times, the coating thickness is about 2 μm.

[0072] The composition and microstructure of the coated zirconium hydride sample were investigated in detail using XRD and SEM, as shown in the figure. Figure 2 The results showed that the Al2O3 coating on the zirconium hydride surface, after heat treatment, was a γ-Al2O3 phase, and the surface of the coating was dense and crack-free.

[0073] Example 3

[0074] In this embodiment, the hydrogen-barrier coating on the surface of the metal hydride material is prepared by using the sol-gel method to prepare a composite hydrogen-barrier coating with an inner layer of Er₂O₃ and an outer layer of Al₂O₃ on the surface of zirconium hydride. The specific steps are as follows:

[0075] (1) When preparing the Er2O3 coating using Example 1, the difference is that step (8) is repeated 5 times from step (4) to step (7) to obtain an Er2O3 coating with a thickness of about 1 μm.

[0076] (2) When preparing the Al2O3 coating using Example 2, the difference is that step (8) repeats steps (4) to (7) 10 times to obtain an Al2O3 coating with a thickness of about 2 μm.

[0077] Example 4

[0078] In this embodiment, the hydrogen-barrier coating on the surface of the metal hydride material is prepared by using the sol-gel method to prepare a composite hydrogen-barrier coating with an inner layer of Al2O3 and an outer layer of Er2O3 on the surface of zirconium hydride. The specific steps are as follows:

[0079] The specific implementation method is to change the order of steps (1) and (2) in Example 3.

[0080] Example 5

[0081] In this embodiment, the hydrogen-barrier coating on the surface of the metal hydride material is prepared by combining the sol-gel method and thermal spraying to prepare a composite hydrogen-barrier coating with an inner layer of Er2O3 and an outer layer of Al2O3 on the surface of zirconium hydride. The specific steps are as follows:

[0082] (1) In order to prevent the high temperature of subsequent thermal spraying from causing the release of hydrogen from zirconium hydride, the Er2O3 coating with a thickness of about 1 μm was prepared first by step (1) of Example 3.

[0083] (2) Clean the surface of the sample with the Er2O3 coating prepared in step (1) to prevent surface impurities from affecting the bonding force between the sprayed coating and Er2O3;

[0084] (3) The powder to be sprayed is Al2O3 powder with a particle size of 1μm;

[0085] (4) Alumina powder coating is performed using Dnepr-3 type explosive spraying equipment;

[0086] (5) The spraying process parameters are: spraying distance 180mm, acetylene volumetric flow rate 1.5m³. 3 / h, oxygen volumetric flow rate 2.4m³ 3 / h, nitrogen volumetric flow rate 0.3m³ 3 / h, explosion frequency 4 times / s, linear velocity 500mm / min, powder conveying mass flow rate 25g / min, spraying time 10min;

[0087] (6) The sample with Al2O3 coating obtained in step (5) was polished with 3000 grit sandpaper and observed under a microscope to control the thickness of the surface Al2O3 coating to be about 2 μm.

[0088] Example 6

[0089] The preparation of the hydrogen barrier coating on the surface of the metal hydride material in this embodiment adopts a combination of sol-gel method and thermal spraying to prepare an Er2O3 and Al2O3 composite coating on the surface of zirconium hydride. The specific steps are as follows.

[0090] (1) In order to prevent the high temperature of subsequent thermal spraying from causing the release of hydrogen from zirconium hydride, the Er2O3 coating with a thickness of about 1 μm was prepared first by step (1) of Example 3.

[0091] (2) Clean the surface of the sample with the Er2O3 coating prepared in step (1) to prevent surface impurities from affecting the bonding force between the sprayed coating and Er2O3;

[0092] (3) The powders used for spraying are Al2O3 powder and Er2O3 powder, with a particle size of 1μm;

[0093] (4) Mix the Al2O3 and Er2O3 powders obtained in step (3) uniformly in a weight ratio of 5:1;

[0094] (5) The Al2O3 / Er2O3 mixed powder was sprayed using a Dnepr-3 type explosive spraying equipment;

[0095] (6) The spraying process parameters are: spraying distance 180mm, acetylene volumetric flow rate 1.5m³. 3 / h, oxygen volumetric flow rate 2.4m³ 3 / h, nitrogen volumetric flow rate 0.3m³ 3 / h, explosion frequency 4 times / s, linear velocity 500mm / min, powder conveying mass flow rate 25g / min, spraying time 10min;

[0096] (7) The sample with Al2O3 / Er2O3 composite coating obtained in step (6) was polished with 3000-grit sandpaper and observed under a microscope to control the thickness of the surface Al2O3 / Er2O3 layer to be about 2μm.

[0097] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0098] Zirconium hydride cores with different coatings and uncoated zirconium hydride cores obtained from Examples 1-6 were placed in quartz glass tubes and protected with argon gas. The quartz glass tubes were then passed horizontally through a muffle furnace. The quartz glass was heated to 500°C at a heating rate of 5°C / min, held for 30 min, and then cooled to room temperature with the furnace. The tested samples were cut along the centerline, and small samples (without coating) were taken from the left and right edges and the center of the cross-section. The hydrogen content was measured and converted to the atomic ratio of H to Zr. The results are summarized below:

[0099]

[0100]

[0101] As shown in the table above, the hydrogen content is better retained after adding the coating, thereby maintaining the material's slowing ability.

[0102] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrogen-barrier coating on the surface of a metal hydride material, characterized in that, include: Surface pretreatment of the metal hydride matrix; Hydrogen-barrier coatings of erbium oxide and aluminum oxide are formed on a metal hydride substrate using a sol-gel method and / or thermal spraying method. The hydrogen barrier coating includes a structure with an inner layer of erbium oxide and an outer layer of aluminum oxide, or a structure with an inner layer of aluminum oxide and an outer layer of erbium oxide, or a structure in which erbium oxide and aluminum oxide are uniformly mixed, or a structure in which erbium oxide and aluminum oxide are in a gradient. The metal hydrides include: zirconium hydride, yttrium hydride, uranium-doped zirconium hydride, or uranium-doped yttrium hydride; The thickness of the hydrogen-barrier coating on the surface of the metal hydride material is 2~5μm.

2. The method for preparing a hydrogen-barrier coating on the surface of a metal hydride material according to claim 1, characterized in that, The preparation of erbium oxide coating using the sol-gel method specifically includes: dissolving erbium-containing salts in collodion to prepare a sol-gel solution with a concentration of 1~5 mol / L; The metal hydride matrix is ​​immersed in a sol-gel solution, and the immersed metal hydride matrix is ​​repeatedly lifted from the sol-gel solution at a lifting speed of 10~100 mm / min at least 10 times using the lifting method. After removing the moisture from the sol-gel solution adhering to the metal hydride matrix by room temperature drying, high-temperature dehydration is performed.

3. The method for preparing a hydrogen-barrier coating on the surface of a metal hydride material according to claim 2, characterized in that, The erbium-containing salts include one or more of erbium nitrate, erbium carbonate, erbium phosphate, and erbium sulfate.

4. The method for preparing a hydrogen-barrier coating on the surface of a metal hydride material according to claim 1, characterized in that, The sol-gel method used to prepare the alumina coating specifically includes: adding aluminum alkoxide to water, heating and stirring for 20 minutes to dissolve it, adding inorganic acid and stirring at 85-95℃ for 3-5 hours to hydrolyze it, and then keeping it at 95-120℃ for 20-40 hours to obtain a clear and transparent Al2O3 sol. The metal hydride matrix was immersed in Al2O3 sol, and the immersed metal hydride matrix was pulled out of Al2O3 sol at a pulling speed of 10~100mm / min using the dip-coating method. After removing the moisture from the sol-gel solution adhering to the metal hydride matrix by drying at room temperature, high-temperature dehydration is performed. The aluminum alkoxides include one or more of aluminum propoxide, aluminum ethoxide, and aluminum n-butoxide.

5. The method for preparing a hydrogen-barrier coating on the surface of a metal hydride material according to claim 3 or 4, characterized in that, The steps for high-temperature dehydration include: heating to 1-300℃ at a heating rate of 2-5℃ / min, and holding at that temperature for 20-50min. Heat to 400-700℃ at a heating rate of 5-7℃ / min, and hold for 10-40 minutes.

6. The method for preparing a hydrogen-barrier coating on the surface of a metal hydride material according to claim 1, characterized in that, The hydrogen-barrier coating was prepared using a thermal spraying method, which specifically involved: taking Al₂O₃ and / or Er₂O₃ powder with a particle size of 1-5 μm, spraying at a distance of 150-200 mm, and using an acetylene volumetric flow rate of 1-3 m³ / g. 3 / h, oxygen volumetric flow rate 1~4m³ 3 / h, nitrogen volumetric flow rate 0.1~1m³ 3 / h, explosion frequency 2~10 times / s, linear velocity 400~600mm / min, powder conveying mass flow rate 20~30g / min, spraying time 5~20min, followed by polishing.

7. A metal hydride material prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The hydrogen-barrier coating on the surface of the metal hydride material includes erbium oxide and aluminum oxide layers.

8. The metal hydride material according to claim 7, characterized in that, When the hydrogen-barrier coating on the surface of the metal hydride material includes an erbium oxide coating and an aluminum oxide coating, the erbium oxide coating and the aluminum oxide coating are uniformly and / or have a gradient distribution.

9. The application of a metal hydride material as described in any one of claims 7 to 8 in a nuclear reactor.

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