A yttrium hydride material with a hydrogen permeation barrier coating and a method for preparing the hydrogen permeation barrier coating.

Abstract

This invention provides a yttrium hydride material with a hydrogen permeation barrier coating and a method for preparing the hydrogen permeation barrier coating. The method includes the following steps: adding aluminum salt and chromium salt to a mixed solvent containing alcohol, reacting with stirring, and aging to prepare an alumina and chromium oxide composite sol-gel system; immersing a cleaned yttrium hydride substrate into the alumina and chromium oxide composite sol-gel system, and forming a composite sol-gel film on the surface of the yttrium hydride substrate using an dip-coating method; and calcining the yttrium hydride substrate containing the composite sol-gel film to transform the composite sol-gel film into a dense hydrogen permeation barrier coating. This invention prepares the raw materials constituting the coating into a sol system, and uses an dip-coating + calcination method to form a hydrogen permeation barrier coating on the surface of the yttrium hydride substrate. The yttrium hydride material with the hydrogen permeation barrier coating can be used in small nuclear reactors as a neutron moderator, which can effectively improve the service life of the yttrium hydride material.

Description

Technical Field

[0001] This invention relates to the field of metal hydride material protection technology, and in particular to a yttrium hydride material containing a hydrogen permeation barrier coating and a method for preparing the hydrogen permeation barrier coating. Background Technology

[0002] Small mobile reactors (SMRs) offer convenient deployment, high energy density, and long service life, making them highly promising for applications in deep space exploration, remote land and sea power supply, and nuclear thermal propulsion. Moderators are essential functional components of SMR cores, converting fast neutrons produced by nuclear fission into thermal neutrons, thereby effectively reducing the critical mass and volume of the uranium-235 nuclear fuel. Yttrium hydride (YHH) possesses high hydrogen density (up to 2% or more) and low high-temperature decomposition pressure (approximately 1.3–4.0 Pa at reactor operating temperatures), making it a preferred choice for space reactors, ground-based mobile reactors, and shipborne mobile reactors. The core indicator for YHHH as a moderator is its hydrogen content. A key characteristic is its stability at high temperatures; however, at higher temperatures (>800℃), higher power, and longer service lives, there is a problem of slow hydrogen release. Furthermore, hydrogen released during long-term core operation can easily diffuse into the reactor vessel, such as fuel assemblies. The release of hydrogen reduces the moderating ability of yttrium hydride, limiting its long-term high-temperature application and shortening the reactor's lifespan; on the other hand, it can easily cause slow failure of materials inside the reactor vessel, such as fuel assemblies.

[0003] Therefore, how to effectively reduce or slow down hydrogen loss in yttrium hydride during service has become a critical technical problem that needs to be solved for this material to operate in a reactor. Summary of the Invention

[0004] To address the problems existing in the background art, the present invention provides a yttrium hydride material with a hydrogen permeation barrier coating and a method for preparing the hydrogen permeation barrier coating, so as to improve the service life of yttrium hydride moderator.

[0005] The specific details of the invention are as follows:

[0006] In a first aspect, the present invention provides a method for preparing a hydrogen permeation barrier coating on a yttrium hydride substrate, the method comprising the following steps:

[0007] S1. Add aluminum salt and chromium salt to a mixed solvent containing alcohol, and after stirring and aging, prepare an alumina and chromium oxide composite sol-gel system.

[0008] S2. The cleaned yttrium hydride substrate is immersed in the alumina and chromium oxide composite sol-gel system, and a composite sol-gel film is formed on the surface of the yttrium hydride substrate by dip-coating method.

[0009] S3. The yttrium hydrogenation matrix containing the composite sol-gel film layer is calcined to transform the composite sol-gel film layer into a dense hydrogen-impermeable coating.

[0010] The aluminum salt is selected from at least one of aluminum n-propoxide, aluminum isopropoxide, aluminum chloride, and aluminum nitrate.

[0011] The chromium salt is selected from chromium nitrate, chromium acetate, chromium chloride, or chromium isopropoxide;

[0012] The alcohol is selected from at least one of anhydrous ethanol, isopropanol, isoamyl alcohol, and ethylene glycol.

[0013] Optionally, in step S1, the mass ratio of the aluminum salt to the chromium salt is 1:(0.1~1).

[0014] Optionally, in step S1, the mixed solvent is formed by mixing the alcohol and deionized water;

[0015] The mass ratio of the deionized water to the alcohol is (1-50):(10-50).

[0016] Optionally, in step S1, the stirring reaction is carried out at 20 ℃ to 100 ℃ for 1 to 12 h.

[0017] The aging process lasts for 6 to 48 hours.

[0018] Optionally, in step S2, the process of forming a composite sol-gel film on the yttrium hydride substrate using the dip-lift method includes: during the dip-lift process, the dip time is 1 to 30 minutes, the number of lifts is 1 to 50, the lift speed is 1 to 10 cm / min, and after the lift is completed, the film is placed in room temperature air to air dry naturally.

[0019] Optionally, in step S3, the calcination process is carried out in a mixed atmosphere of hydrogen and inert gas;

[0020] The calcination treatment is carried out at a temperature of 600 ℃~700 ℃ for a time of 20~40 h;

[0021] The calcination process is carried out at a pressure of 30–40 kPa.

[0022] Optionally, in step S3, the temperature control process during the calcination treatment includes:

[0023] The roasting furnace is heated to 200℃ at a rate of 3℃~5℃ / min and held for 4~6 hours. Then, the temperature is increased to 600℃~700℃ at a rate of 5℃~10℃ / min and held for 20~40 hours. Finally, the temperature is reduced to 200℃ at a rate of 5~10℃ / min and then allowed to cool naturally.

[0024] Optionally, the volume percentage of hydrogen in the mixed atmosphere is 0.01% to 1%.

[0025] Optionally, the surface of yttrium hydride is cleaned with a mixed acid and anhydrous ethanol solution to obtain the cleaned yttrium hydride matrix;

[0026] The mixed acid is formed by mixing 30%–40% phosphoric acid or nitric acid, 35%–45% glycerol, and 15%–35% ethanol.

[0027] In a second aspect, the present invention provides a yttrium hydride material containing a hydrogen permeation barrier coating, wherein the hydrogen permeation barrier coating on the surface of the yttrium hydride material is obtained by the preparation method described in the first aspect above.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] This invention provides a method for preparing a hydrogen permeation barrier coating on a yttrium hydride substrate. The method includes the following steps: S1, adding aluminum salt and chromium salt to a mixed solvent containing alcohol, reacting with stirring, and aging to prepare an alumina and chromium oxide composite sol-gel system; S2, immersing the cleaned yttrium hydride substrate in the alumina and chromium oxide composite sol, and forming a composite sol-gel film on the surface of the yttrium hydride substrate using an dip-coating method; S3, calcining the yttrium hydride substrate containing the composite sol-gel film to transform the composite sol-gel film into a dense hydrogen permeation barrier coating; wherein, the aluminum salt is selected from at least one of aluminum propoxide, aluminum isopropoxide, aluminum chloride, and aluminum nitrate; the chromium salt is selected from chromium nitrate, chromium acetate, chromium chloride, or chromium isopropoxide; and the alcohol is selected from at least one of anhydrous ethanol, isopropanol, isoamyl alcohol, and ethylene glycol.

[0030] This invention prepares the raw materials constituting the coating into a sol system and uses an impregnation-pulling and calcination method to form a hydrogen-impermeable coating on the surface of a yttrium hydride substrate. Compared with the vapor deposition method for preparing coatings, this method has the advantages of simple operation, uniform and dense oxide coating, and effective composite of multiple oxide materials. It is also not limited by the shape and structure of complex substrates. When yttrium hydride materials containing hydrogen-impermeable coatings are used in small nuclear reactors as neutron moderators, they can effectively improve the service life of yttrium hydride materials. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A flowchart illustrating the preparation method of a hydrogen permeation barrier coating on a yttrium hydride substrate provided in an embodiment of the present invention is shown.

[0033] Figure 2 The TG-DSC curves of yttrium hydride at different temperatures are shown.

[0034] Figure 3 The SEM morphology of the surface hydrogen permeation barrier coating provided in an embodiment of the present invention is shown.

[0035] Figure 4 The XRD phase diagram of the surface hydrogen permeation barrier coating provided in an embodiment of the present invention is shown. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0037] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0038] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0039] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] Currently, yttrium hydride and related materials are still in the research stage both domestically and internationally, with few publicly available literature documents on related research. Figure 2 The TG-DSC curves of yttrium hydride at different temperatures are shown, as follows: Figure 2 As shown, when the temperature exceeds 800℃, hydrogen in yttrium hydride begins to be released slowly, and the release of hydrogen accelerates at 870℃. To suppress high-temperature hydrogen loss, patent CN202311718309.X discloses a hydrogen-blocking coating on the surface of a metal hydride material and its preparation method. The hydrogen-blocking coating is formed on the metal hydride substrate by using a sol-gel method and / or thermal spraying method to form at least one of erbium oxide coating, aluminum oxide coating, and a mixed layer of erbium oxide and aluminum oxide, so as to suppress high-temperature hydrogen loss.

[0041] In the reactor environment containing an oxidizing atmosphere, hydrogen loss from yttrium hydride requires consideration not only of suppressing high-temperature hydrogen loss but also of the oxidative corrosion resistance of the yttrium hydride moderator within the reactor. Therefore, the hydrogen-blocking coating prepared on the yttrium hydride surface should also possess excellent oxidative corrosion resistance. Alumina and chromium oxide are considered promising high-temperature antioxidant protective coatings, exhibiting excellent matching characteristics in their coefficients of thermal expansion. This invention aims to generate a protective coating material on the yttrium hydride surface to effectively hinder hydrogen penetration and diffusion, thereby significantly reducing effective hydrogen diffusion and extending the service life of the yttrium hydride moderator. However, yttrium hydride moderator components are often heavy, irregularly shaped, and brittle. Therefore, the suitability of the preparation method must be considered when preparing the coating on its surface, and the choice of preparation method is easily limited by the complex shape and structure of the substrate.

[0042] Based on this, the present invention prepares the raw materials constituting the coating into a sol-gel system and uses an impregnation-coating and calcination method to form a hydrogen-permeability-blocking coating on the surface of a yttrium hydride substrate. Compared with the vapor deposition method for preparing coatings, this method has the advantages of simple operation, uniform and dense oxide coating, and effective composite of multiple oxide materials, and is not limited by the complex shape and structure of the substrate. The yttrium hydride material containing the hydrogen-permeability-blocking coating can be used as a neutron moderator in small nuclear reactors, which can effectively improve the service life of the yttrium hydride material. Specific implementation methods are described below:

[0043] In a first aspect, the present invention provides a method for preparing a hydrogen permeation barrier coating on a yttrium hydride substrate surface. Figure 1 A flowchart illustrating the preparation method of a hydrogen permeation barrier coating on a yttrium hydride substrate provided in this embodiment of the invention is shown, as follows: Figure 1 As shown, the method includes the following steps:

[0044] S1. Add aluminum salt and chromium salt to a mixed solvent containing alcohol, and after stirring and aging, prepare an alumina and chromium oxide composite sol-gel system.

[0045] In this specific implementation step, the aluminum salt can be selected from at least one of aluminum propoxide, aluminum isopropoxide, aluminum chloride, and aluminum nitrate; the chromium salt can be selected from chromium nitrate, chromium acetate, chromium chloride, or chromium isopropoxide; and the alcohol can be selected from at least one of anhydrous ethanol, isopropanol, isoamyl alcohol, and ethylene glycol.

[0046] In this step, the mass ratio of aluminum salt to chromium salt is 1:(0.1~1).

[0047] In this specific implementation step, the mixed solvent is formed by mixing deionized water and the alcohol; wherein the mass ratio of deionized water to the alcohol is 1:(0.2-10).

[0048] In this step, the stirring reaction is carried out at 20 ℃~100 ℃ for 1~12 h; the aging treatment lasts for 6~48 h.

[0049] This step involves a hydrolysis-condensation reaction between aluminum and chromium salts to form an Al2O3-Cr2O3 composite sol-gel system. An appropriate amount of alcohol is present as a reaction medium, which effectively controls the rate of the hydrolysis-condensation reaction and regulates the viscosity of the resulting composite sol-gel system. This ensures that the composite sol-gel can effectively adhere to the yttrium hydride substrate surface during the subsequent impregnation and lifting process, forming a composite sol-gel film.

[0050] S2. The cleaned yttrium hydride substrate is immersed in the alumina and chromium oxide composite sol-gel system, and a composite sol-gel film is formed on the surface of the yttrium hydride substrate by dip-coating method.

[0051] It should be noted that the yttrium hydride substrate used in this step is a yttrium hydride material used as a neutron moderator in small nuclear reactors. When preparing the hydrogen permeation barrier coating, the surface of the yttrium hydride substrate must be absolutely clean and dry; any oxides or moisture will reduce the coating adhesion. Therefore, before immersing the yttrium hydride substrate into the alumina and chromium oxide composite sol-gel system, the yttrium hydride surface is first cleaned with a mixed acid and anhydrous ethanol solution to remove surface mechanical impurities, oil, and oxide layers, obtaining a clean yttrium hydride substrate.

[0052] In some embodiments, the cleaning mixed acid is formed by mixing 30% to 40% phosphoric acid or nitric acid, 35% to 45% glycerol, and 15% to 35% ethanol.

[0053] In this step, during the dip-lift process, the dip time and lifting speed must be strictly controlled. By controlling the lifting speed (which affects film thickness) and the sol viscosity (which is adjusted by aging time and concentration), a uniform wet film can be formed on the substrate surface. If the lifting speed is too fast, streaks will be produced; if it is too slow, the film layer will be too thick and prone to cracking. During the dip-lift process, the dip time for each dip is 1 to 30 minutes, the number of lifts is 1 to 50, and the lifting speed is 1 to 10 cm / min. After the lift is completed, the film should be placed in room temperature air to air dry naturally.

[0054] In some embodiments, during the immersion and lifting process, the immersion time is preferably 2 to 20 minutes, the number of liftings is preferably 2 to 20, and the lifting speed is preferably 2 to 5 cm / min.

[0055] S3. The yttrium hydrogenation matrix containing the composite sol-gel film layer is calcined to transform the composite sol-gel film layer into a dense hydrogen-impermeable coating.

[0056] In this step, the calcination process is carried out in a mixed atmosphere of hydrogen and inert gas, with the volume percentage of hydrogen in the mixed atmosphere being 0.01% to 1%. The presence of an appropriate amount of hydrogen in the mixed atmosphere can effectively prevent the decomposition of the yttrium hydride matrix at high temperatures. The calcination temperature is 600 ℃ to 700 ℃, the pressure is 30 to 40 kPa, and the time is 20 to 40 h.

[0057] In this specific implementation step, the calcination treatment is carried out using a gradient temperature control method. The temperature control process includes: the calcination furnace is heated to 200 ℃ at a rate of 3 ℃~5 ℃ / min, held for 4~6 h, then heated to 600 ℃~700 ℃ at a rate of 5 ℃~10 ℃ / min, held for 20~40 h, and then cooled to 200 ℃ at a rate of 5~10 ℃ / min, followed by natural furnace cooling. The low-temperature calcination stage (200 ℃, held for 4~6 h) removes organic solvents, residual hydroxyl groups, and impurity salts. The medium-high temperature calcination stage (600 ℃~700 ℃, held for 20~40 h) transforms amorphous Al / Cr hydroxide into crystalline Al2O3 / Cr2O3, which is densified by volume shrinkage, ultimately forming a hydrogen-impermeable coating composed of a mixture of alumina and chromium oxide on the surface of the yttrium hydride substrate.

[0058] It should be noted that the calcination temperature needs to be controlled below 700 ℃ to protect the yttrium hydride matrix from high-temperature damage.

[0059] It should be noted that before heating, the calcination system is first evacuated to 10⁻³ to 10⁻⁴ Pa. When the pressure rise rate is less than 1 Pa / h, the evacuation is stopped. Then, argon, helium, or a mixture of helium and a certain amount of hydrogen is introduced at 30 to 40 kPa. Then, high-temperature atmosphere heat treatment is carried out according to the preset gradient temperature control method.

[0060] In a second aspect, the present invention provides a yttrium hydride material containing a hydrogen permeation barrier coating, wherein the hydrogen permeation barrier coating on the surface of the yttrium hydride material is obtained by the preparation method described in the first aspect above.

[0061] The present invention obtains a yttrium hydride material with a hydrogen permeation barrier coating through the preparation method provided in the first aspect above; wherein the thickness of the hydrogen permeation barrier coating is 0.01 to 30 μm; the coating is continuous, uniform and dense, and is not limited by the shape and structure of complex substrates; the obtained yttrium hydride material with a hydrogen permeation barrier coating is applied to a small nuclear reactor as a neutron moderator, which can effectively improve the service life of the yttrium hydride material.

[0062] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to provide a detailed description of the yttrium hydride material containing a hydrogen permeation barrier coating and the preparation method of the hydrogen permeation barrier coating according to the present invention.

[0063] Example 1

[0064] A mixed acid solution was prepared by mixing phosphoric acid, glycerol, and ethanol in a volume ratio of 30:35:35. The yttrium hydride matrix was then immersed in the mixed acid solution and ultrasonically cleaned for 5 minutes. Next, it was immersed in anhydrous ethanol solution and ultrasonically cleaned for 5 minutes. The matrix was then removed and dried in an oven to obtain a cleaned yttrium hydride matrix.

[0065] By weight, 1 part of aluminum propoxide and 1 part of chromium nitrate were added to 20 parts of deionized water and 50 parts of ethanol to dissolve. The mixture was heated to 35°C and stirred for 10 hours. The resulting product was aged at room temperature for 24 hours to obtain a uniform and stable alumina and chromium oxide composite sol-gel system.

[0066] The cleaned yttrium hydride substrate was immersed in the composite sol-gel system for 10 min, and then pulled out at a lifting speed of 0.5 cm / min. This step was repeated twice, and the substrate was allowed to air dry naturally. A composite sol-gel film was formed on the surface of the yttrium hydride substrate.

[0067] The yttrium hydride matrix containing the composite sol-gel film layer was placed in the heat treatment furnace. The furnace body was evacuated to 10⁻³ to 10⁻⁴ Pa using a combination of mechanical pump and molecular pump. When the pressure rise rate was less than 1 Pa / h, the vacuum system was turned off. A mixture of 30 kPa high-purity helium and high-purity hydrogen was introduced into the sample chamber of the heat treatment furnace. The temperature was controlled in stages according to the following procedure: (1) the temperature was increased from room temperature to 200℃ at 3℃ / min and held for 4 hours; (2) the temperature was increased from 200℃ to 600℃ at 5℃ / min and held for 20 hours; (3) the temperature was decreased from 600℃ to 200℃ at 5℃ / min and allowed to cool naturally in the furnace.

[0068] Figure 3 The surface SEM morphology of the hydrogen permeation barrier coating provided in the embodiment of the present invention is shown, such as... Figure 3 As shown, the coating is continuous and dense.

[0069] Figure 4 The XRD phase spectrum of the surface hydrogen permeation barrier coating provided in the embodiment of the present invention is shown, as follows: Figure 4 As shown, the hydrogen permeation barrier coating prepared in this embodiment of the invention contains Al2O3 and Cr2O3 phases.

[0070] Example 2

[0071] A mixed acid solution was prepared by mixing nitric acid, glycerol, and ethanol in a volume ratio of 40:45:15. The yttrium hydride sample was then placed into the mixed acid solution and anhydrous ethanol solution in sequence, and ultrasonically cleaned for 5 minutes each. The sample was then removed and dried in an oven. The cleaned yttrium hydride matrix was obtained.

[0072] By weight, 1 part aluminum chloride and 0.5 parts chromium acetate were added to 10 parts deionized water and 30 parts ethylene glycol solvent for mixing and dissolution. The mixture was heated to 50°C and stirred for 9 h. The resulting product was aged at room temperature for 12 h to obtain a uniform and stable alumina and chromium oxide composite sol-gel system.

[0073] The cleaned yttrium hydride substrate was immersed in an alumina and chromium oxide composite sol-gel system for 2 minutes, and then pulled out at a speed of 1 cm / min. This step was repeated 12 times, and the substrate was allowed to air dry naturally. A composite sol-gel film was formed on the surface of the yttrium hydride substrate.

[0074] The yttrium hydride matrix containing the composite sol-gel film layer was placed in the heat treatment furnace. The furnace body was evacuated to 10⁻³ to 10⁻⁴ Pa using a combination of mechanical pump and molecular pump. When the pressure rise rate was less than 1 Pa / h, the vacuum system was turned off. A mixture of 40 kPa high-purity argon and high-purity hydrogen was introduced into the sample chamber of the heat treatment furnace. The temperature was controlled in stages according to the following procedure: (1) the temperature was increased from room temperature to 200℃ at 3℃ / min and held for 6 hours; (2) the temperature was increased from 200℃ to 700℃ at 5℃ / min and held for 30 hours; (3) the temperature was decreased from 700℃ to 200℃ at 5℃ / min and allowed to cool naturally in the furnace.

[0075] The hydrogen permeation barrier coating formed by the mixture of alumina and chromium oxide obtained in this embodiment has a thickness of about 20 μm and is uniform, continuous and dense.

[0076] Example 3

[0077] A mixed acid solution was prepared by mixing phosphoric acid, glycerol, and ethanol in a volume ratio of 35:40:25. The yttrium hydride sample was then placed into the mixed acid solution and anhydrous ethanol solution in sequence, and ultrasonically cleaned for 5 minutes each. The sample was then removed and dried in an oven to obtain a cleaned yttrium hydride matrix.

[0078] By weight, 1 part aluminum nitrate and 0.1 part chromium chloride were added to 40 parts deionized water and 20 parts isoamyl alcohol solvent for mixing and dissolution. The mixture was heated to 80°C and stirred for 6 h. The resulting product was aged at room temperature for 6 h to obtain a uniform and stable alumina and chromium oxide composite sol-gel system.

[0079] The cleaned yttrium hydride substrate was immersed in the composite sol-gel system for 15 minutes, and then pulled out at a speed of 3 cm / min. This step was repeated 20 times, and the substrate was allowed to air dry naturally. A composite sol-gel film was formed on the surface of the yttrium hydride substrate.

[0080] The yttrium hydride matrix containing the composite sol-gel film layer was placed in the heat treatment furnace. The furnace body was evacuated to 10⁻³ to 10⁻⁴ Pa using a combination of mechanical pump and molecular pump. When the pressure rise rate was less than 1 Pa / h, the vacuum system was turned off. A mixture of high-purity helium and hydrogen (hydrogen volume content 1%) was introduced into the sample chamber of the heat treatment furnace at 35 kPa. The temperature was controlled in stages according to the following procedure: (1) the temperature was increased from room temperature to 200℃ at 3℃ / min and held for 6 hours; (2) the temperature was increased from 200℃ to 600℃ at 5℃ / min and held for 30 hours; (3) the temperature was decreased from 600℃ to 200℃ at 5℃ / min and allowed to cool naturally in the furnace.

[0081] The hydrogen permeation barrier coating formed by the mixture of alumina and chromium oxide obtained in this embodiment has a thickness of about 20 μm and is uniform, continuous and dense.

[0082] Example 4

[0083] A mixed acid solution was prepared by mixing phosphoric acid, glycerol, and ethanol in a volume ratio of 35:40:25. The yttrium hydride sample was then placed into the mixed acid solution and anhydrous ethanol solution in sequence, and ultrasonically cleaned for 5 minutes each. The sample was then removed and dried in an oven to obtain a cleaned yttrium hydride matrix.

[0084] By weight, 1 part aluminum isopropoxide and 1 part chromium isopropoxide were added to 5.5 parts deionized water and 35 parts isopropanol solvent for mixing and dissolution. The mixture was heated to 80°C and stirred for 6 h. The resulting product was aged at room temperature for 48 h to obtain a uniform and stable alumina and chromium oxide composite sol-gel system.

[0085] The cleaned yttrium hydride substrate was immersed in the composite sol-gel system for 1.5 min, and then pulled out at a lifting speed of 2.5 cm / min. This step was repeated 8 times, and the substrate was allowed to air dry naturally. A composite sol-gel film was formed on the surface of the yttrium hydride substrate.

[0086] The yttrium hydride matrix containing the composite sol-gel film was placed in the heat treatment furnace. The furnace body was evacuated to 10⁻³ to 10⁻⁴ Pa using a combination of mechanical pump and molecular pump. When the pressure rise rate was less than 1 Pa / h, the vacuum system was turned off. A mixture of 30 kPa high-purity helium and hydrogen gas (hydrogen volume content 0.01%) was introduced into the sample chamber of the heat treatment furnace. The temperature was controlled in stages according to the following procedure: (1) the temperature was increased from room temperature to 200℃ at 3℃ / min and held for 6 hours; (2) the temperature was increased from 200℃ to 700℃ at 5℃ / min and held for 30 hours; (3) the temperature was decreased from 700℃ to 200℃ at 5℃ / min and allowed to cool naturally in the furnace.

[0087] The hydrogen permeation barrier coating formed by the mixture of alumina and chromium oxide obtained in this embodiment has a thickness of about 30 μm and is uniform, continuous and dense.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0089] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0090] The foregoing has provided a detailed description of a yttrium hydride material with a hydrogen permeation barrier coating and a method for preparing the hydrogen permeation barrier coating provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for producing a hydrogen permeation barrier coating on the surface of a yttrium hydride substrate, characterized by, The method comprises the following steps: S1, adding aluminum salt and chromium salt into a mixed solvent containing alcohol, and preparing an alumina and chromium oxide composite sol-gel system after stirring reaction and aging treatment; S2, immersing the cleaned yttrium hydride matrix into the alumina and chromium oxide composite sol-gel system, and forming a composite sol-gel film layer on the surface of the yttrium hydride matrix by dip-coating method; S3, performing calcination treatment on the yttrium hydride matrix containing the composite sol-gel film layer, so that the composite sol-gel film layer is converted into a dense hydrogen permeation resistant coating; The aluminum salt is selected from at least one of aluminum propylate, aluminum isopropylate, aluminum chloride and aluminum nitrate; The chromium salt is selected from chromium nitrate, chromium acetate, chromium chloride or chromium isopropylate; The alcohol is selected from at least one of anhydrous ethanol, isopropyl alcohol, isoamyl alcohol and ethylene glycol; In step S1, the mass ratio of the aluminum salt to the chromium salt is 1:(0.1-1); In step S3, the calcination treatment is performed in a mixed gas atmosphere composed of hydrogen and inert gas; The temperature of the calcination treatment is 600-700℃, and the time is 20-40h; The pressure of the calcination treatment is 30-40kPa; In step S3, the volume ratio of hydrogen in the mixed gas atmosphere is 0.01%-1%; and in the calcination treatment, the temperature control process comprises: The calcination furnace is raised to 200℃ at a rate of 3-5℃ / min, and then kept at this temperature for 4-6h; then the temperature is raised to 600-700℃ at a rate of 5-10℃ / min, and kept at this temperature for 20-40h; then the temperature is lowered to 200℃ at a rate of 5-10℃ / min, and then the furnace is naturally cooled.

2. The method for preparing a hydrogen permeation barrier coating on a yttrium hydride substrate according to claim 1, characterized in that, In step S1, the mixed solvent is obtained by mixing the alcohol with deionized water; The mass ratio of the deionized water to the alcohol is (1-50):(10-50).

3. The method for preparing a hydrogen permeation barrier coating on a yttrium hydride substrate according to claim 1, characterized in that, In step S1, the stirring reaction is performed at 20-100℃ for 1-12h; The aging treatment is performed for 6-48h.

4. The method for preparing a hydrogen permeation barrier coating on a yttrium hydride substrate according to claim 1, characterized in that, In step S2, the composite sol-gel film layer is formed on the surface of the yttrium hydride matrix by dip-coating method, which comprises the following steps: in the dip-coating process, each time of dipping is performed for 1-30min, the number of pulling is 1-50, the pulling speed is 1-10cm / min, and after the pulling is completed, the sample is naturally air-dried at room temperature.

5. The method for preparing a hydrogen permeation barrier coating on a yttrium hydride substrate according to claim 1, characterized in that, The surface of the yttrium hydride is cleaned by using a mixed acid and anhydrous ethanol solution to obtain the cleaned yttrium hydride matrix; The mixed acid is formed by mixing 30%-40% phosphoric acid or nitric acid, 35%-45% glycerol and 15%-35% ethanol in a volume ratio.

6. A hydrogen permeation barrier coated yttrium hydride material, characterized in that, The hydrogen permeation resistant coating on the surface of the yttrium hydride material is obtained by the preparation method of any one of claims 1-5.

Images