Composite intermediate layer of accelerator neutron source target system, preparation method and application of composite intermediate layer

Abstract

The invention relates to the field of medical apparatus and instruments, and discloses a composite interlayer of an accelerator neutron source target system, a preparation method and application thereof. The composite intermediate layer is located between an acting layer and a substrate of the accelerator neutron source target system and comprises at least one stress relief layer and at least one hydrogen embrittlement resisting layer which are stacked in a staggered mode. The stress relief layer located at the bottommost layer is arranged on the upper surface of the substrate, and the hydrogen embrittlement resistant layer located at the topmost layer is arranged on the lower surface of the acting layer. A middle layer (a hydrogen embrittlement resistant material) of a traditional accelerator neutron source target system is designed into a composite middle layer, namely, the original middle layer is disassembled into at least one hydrogen embrittlement resistant layer, and a stress relief layer is arranged on the lower surface of each hydrogen embrittlement resistant layer. According to the scheme, the adhesiveness, crystallinity, component uniformity, thermal stability and other properties of an original intermediate layer can be improved, so that the binding force between the intermediate layer and the substrate is improved, the problem that an existing intermediate layer is prone to falling off in the preparation process is solved, and the accelerator neutron source target system with high performance and stability is prepared.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and particularly to a composite intermediate layer of an accelerator neutron source target system, a preparation method thereof, and an application thereof. Background Art

[0002] An accelerator neutron source is a device used to generate neutron beams, which plays an important role in many application fields, such as nuclear physics research, medical radiotherapy, and industrial applications. The target system of an accelerator neutron source refers to the target material and related components used to receive the impact of charged particles and generate neutrons. The design and selection of the target system are very important for the performance and application of the neutron source.

[0003] Currently, the accelerator neutron source target system usually consists of a protective layer, an active layer (main target material), an intermediate layer, and a substrate (heat conduction layer). The protective layer plays a role in protection and isolation, the active layer is responsible for generating neutrons, the intermediate layer (mainly composed of hydrogen embrittlement-resistant materials) is used to prevent hydrogen embrittlement from occurring on the substrate (heat conduction layer), and the heat conduction layer conducts heat to ensure that the target system maintains a stable temperature under the bombardment of high-energy particles.

[0004] Currently, in the design of the accelerator neutron source target system, the intermediate layer is often relatively thick (tens or even hundreds of microns) and composed of one material. This leads to the peeling of the intermediate layer due to insufficient bonding strength caused by thermal stress, poor interface, or other factors generated during the deposition process when using the vapor deposition method for processing. In addition, when using the vapor deposition coating method to prepare a relatively thick intermediate layer, residual stress caused by uneven distribution of internal stress in the material due to thermal expansion and cooling will also be generated, resulting in deformation, cracking, or failure of the intermediate layer. These problems have led to the disadvantages of low efficiency and high cost in the preparation of the intermediate layer in the existing solutions. Therefore, it is necessary to develop a new composite intermediate layer solution to improve the preparation efficiency of the intermediate layer of the accelerator neutron source target system. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a composite intermediate layer of an accelerator neutron source target system, a preparation method thereof, and an application thereof. In the present invention, the intermediate layer (hydrogen embrittlement-resistant material) in the traditional accelerator neutron source target system is designed as a composite intermediate layer, that is, the original intermediate layer is disassembled into at least one hydrogen embrittlement-resistant layer, and a stress relief layer is provided on the lower surface of each hydrogen embrittlement-resistant layer. This solution can improve the adhesion, crystallinity, composition uniformity, and thermal stability of the original intermediate layer, thereby improving its bonding force with the substrate, solving the problem of easy detachment during the preparation of the existing intermediate layer, and preparing an accelerator neutron source target system with high performance and stability.

[0006] The specific technical solution of the present invention is as follows: In a first aspect, the present invention provides a composite intermediate layer for an accelerator neutron source target system, which is located between the active layer and the substrate (heat-conducting layer) of the accelerator neutron source target system, and includes at least one stress relief layer and at least one hydrogen embrittlement-resistant layer that are alternately stacked; the stress relief layer located at the bottommost layer is disposed on the upper surface of the substrate, and the hydrogen embrittlement-resistant layer located at the topmost layer is disposed on the lower surface of the active layer.

[0007] In the present invention, the intermediate layer (hydrogen embrittlement-resistant material) of the traditional accelerator neutron source target system is designed as a composite intermediate layer, that is, the original intermediate layer is disassembled into at least one hydrogen embrittlement-resistant layer, and a stress relief layer is disposed on the lower surface of each hydrogen embrittlement-resistant layer. After the introduction of the stress relief layer, an interface layer can be formed, which can be used to improve the properties such as the adhesion, crystallinity, composition uniformity, and thermal stability of the intermediate layer, thereby improving the bonding strength between the intermediate layer and the substrate, and solving the problem of easy peeling off during the preparation of the existing intermediate layer, so as to prepare an accelerator neutron source target system with high performance and stability.

[0008] The principle of the present invention for designing the intermediate layer as at least one stress relief layer and at least one hydrogen embrittlement-resistant layer that are alternately stacked is as follows: First, the originally thick single-layer intermediate layer is disassembled into multiple thinner hydrogen embrittlement-resistant layers. During the processing using methods such as chemical vapor deposition, the technical problems of peeling off of the intermediate layer caused by thermal stress, poor interface, or insufficient bonding strength caused by other factors generated during the deposition process can be alleviated. In addition, it can also reduce the residual stress caused by the uneven distribution of internal stress in the material due to thermal expansion and cooling during the preparation of the thick intermediate layer, thereby avoiding deformation, cracking, or failure of the intermediate layer.

[0009] Second, due to the difference in material properties between the stress relief layer and the hydrogen embrittlement-resistant layer, the introduction of the stress relief layer and the use of the alternately stacked method can alleviate the thermal stress accumulation when a single material is deposited to a certain thickness, make the growth process of the hydrogen embrittlement-resistant layer more stable, and reduce the risk of stress concentration and cracking.

[0010] Preferably, the deviation of the coefficient of thermal expansion of each hydrogen embrittlement-resistant layer relative to the stress relief layer adjacent to its lower surface is ≤ 30%. It can be expressed as satisfying the following relationship: In the formula: α is the coefficient of thermal expansion of the corresponding layer, and the unit is 1 / °C.

[0011] The present invention finds that the coefficient of thermal expansion is the main factor leading to stress accumulation during the thin film deposition process. Therefore, the expansion coefficients of two adjacent layers of materials are controlled within the above specific range. If the difference in expansion coefficients is greater than the above range, it will lead to uneven stress distribution and cause the thin film to rupture. Moreover, since the deposited hydrogen embrittlement resistant layer materials are all grown on the upper surface of the stress relief layer, a good bonding force is required between the lower surface of the hydrogen embrittlement resistant layer and the upper surface of the stress relief layer. Therefore, it is necessary to limit that the expansion coefficient of the hydrogen embrittlement resistant layer and the adjacent stress relief layer on its lower surface satisfies the above formula, rather than the stress relief layer adjacent to its upper surface.

[0012] Preferably, the thickness of a single layer of the stress relief layer is ≤ 1 μm, and more preferably ≤ 0.05 μm.

[0013] During the operation of the accelerator neutron source, the temperature of the target will rise due to the deposition of proton energy. Therefore, it is necessary to cool the target. If the added stress relief layer is too thick, it will increase the difficulty of cooling the target. If the ideal cooling effect cannot be achieved, it will cause the target temperature to rise and even melt. For this reason, the present invention limits the thickness of a single layer of the stress relief layer within the above range.

[0014] Preferably, the thickness of a single layer of the hydrogen embrittlement resistant layer is 0.2 - 2 μm, and more preferably 0.8 - 1.2 μm.

[0015] For most hydrogen embrittlement resistant layer materials, the overall optimal thickness is 20 - 30 μm. Considering that the thin film stress will accumulate with the increase of the film thickness, the thickness of each layer needs to ensure that the stress will not cause the thin film to crack. For this reason, the present invention limits the thickness of a single layer of the hydrogen embrittlement resistant layer within the above range.

[0016] Preferably, the number of layers of both the stress relief layer and the hydrogen embrittlement resistant layer is n, where n = the total required thickness of the hydrogen embrittlement resistant layer / the thickness of a single layer of the hydrogen embrittlement resistant layer.

[0017] The total required thickness of the hydrogen embrittlement resistant layer is determined by the proton energy passing through the functional layer (such as the lithium layer) and the selected hydrogen embrittlement resistant layer material. That is, the total thickness of the target system and the hydrogen embrittlement resistant layer is obtained through nuclear physics calculations according to the requirements of the neutron source target material. According to the parameters and requirements of different neutron sources, the determined thickness is different and can be determined according to actual needs.

[0018] Preferably, the material of the stress relief layer is selected from one or more of chromium, titanium, zirconium, zinc, silicon, boron and their carbides and nitrides.

[0019] The present invention selects the above elements as the materials for the stress relief layer. In addition to the thermal expansion coefficient thereof needing to conform to the foregoing formula, in order to further ensure the timely cooling of the target, the thermal conductivity is also one of the indexes for evaluating the material as the stress relief layer. The above several materials have good thermal conductivity while meeting the expansion coefficient, so they are preferred materials.

[0020] Preferably, the material of the hydrogen embrittlement resistant layer is selected from one or more of tantalum, vanadium, palladium, niobium, platinum, tungsten and their corresponding oxides.

[0021] More preferably, the material of the stress relief layer is chromium and the material of the hydrogen embrittlement resistant layer is tantalum; or the material of the stress relief layer is titanium and the material of the hydrogen embrittlement resistant layer is tantalum; or the material of the stress relief layer is zirconium and the material of the hydrogen embrittlement resistant layer is tantalum; or the material of the stress relief layer is chromium and the material of the hydrogen embrittlement resistant layer is niobium; or the material of the stress relief layer is titanium and the material of the hydrogen embrittlement resistant layer is niobium.

[0022] Preferably, the materials of each stress relief layer or hydrogen embrittlement resistant layer are the same or different.

[0023] Designing the materials of each stress relief layer or hydrogen embrittlement resistant layer to be different, compared with selecting the same material for all, the film thickness corresponding to the stress generated by different materials is different. That is to say, the maximum stress accumulated when the film ruptures is different. Therefore, the preparation efficiency of the target can be improved by reasonably arranging the material sequence.

[0024] In a second aspect, the present invention provides a method for preparing a composite intermediate layer of the above accelerator neutron source target system, including the following steps: S1: Deposit the bottom stress relief layer on the upper surface of the substrate; S2: Deposit the bottom hydrogen embrittlement resistant layer on the upper surface of the stress relief layer obtained in the previous step; S3: According to needs, on the basis of S2, deposit the remaining stress relief layers and hydrogen embrittlement resistant layers in sequence.

[0025] Preferably, the deposition method is physical vapor deposition, chemical vapor deposition, solution spin coating, dipping, spraying, electrochemical deposition, sol-gel method or molecular beam epitaxy.

[0026] Preferably, each stress relief layer or hydrogen embrittlement resistant layer adopts the same or different deposition methods.

[0027] For different materials, the quality of the films obtained by different deposition methods is different, and the stress generation methods are also different (for example, for the same material film with a thickness of 1 micron, the stresses generated by magnetron sputtering and evaporation are also different). Therefore, selecting the corresponding deposition method for different materials will be more conducive to the processing of the overall structure.

[0028] Preferably, the substrate is pre-treated by surface cleaning to remove surface impurities and oil stains, and further preferably polishing, ultrasonic cleaning, drying, etc.

[0029] In a third aspect, the present invention provides an application of the above composite intermediate layer in an accelerator neutron source target system, and the accelerator neutron source target system includes: A substrate; The composite intermediate layer provided on the upper surface of the substrate; A functional layer provided on the upper surface of the composite intermediate layer; A protective layer covering the outer surfaces of the functional layer and the composite intermediate layer.

[0030] Preferably, the functional layer is a lithium target layer or a beryllium target layer.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: In the present invention, the intermediate layer (hydrogen embrittlement-resistant material) in the traditional accelerator neutron source target system is designed as a composite intermediate layer, that is, the original intermediate layer is disassembled into at least one hydrogen embrittlement-resistant layer, and a stress relief layer is provided on the lower surface of each hydrogen embrittlement-resistant layer. First, the originally thicker single-layer intermediate layer is disassembled into multiple thinner hydrogen embrittlement-resistant layers. During the processing by methods such as vapor deposition, technical problems such as the thermal stress generated during deposition, poor interface, or insufficient bonding strength caused by other factors leading to the peeling of the intermediate layer can be alleviated. In addition, it can also reduce the residual stress caused by the uneven distribution of internal stress in the material due to thermal expansion and cooling during the preparation of the thicker intermediate layer, thereby avoiding deformation, cracking, or failure of the intermediate layer. Secondly, the introduction of the stress relief layer and the use of the staggered stacking method can alleviate the thermal stress accumulation when a single material is deposited to a certain thickness due to the difference in material properties between the stress relief layer and the hydrogen embrittlement-resistant layer, making the growth process of the hydrogen embrittlement-resistant layer more stable and reducing the risk of stress concentration and cracking. Therefore, the composite intermediate layer of the present invention can improve the adhesion, crystallinity, composition uniformity, thermal stability and other properties of the original intermediate layer, thereby improving its bonding force with the substrate, solving the problem of easy peeling during the preparation of the existing intermediate layer, and preparing an accelerator neutron source target system with high performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a typical structure of the composite intermediate layer of the accelerator neutron source target system of the present invention; Figure 2It is a workpiece diagram of Comparative Example 1 in which an anti-hydrogen embrittlement layer (tantalum) is directly deposited on a substrate by magnetron sputtering; Figure 3 It is a workpiece diagram of Example 1 in which a stress relief layer (chromium) and an anti-hydrogen embrittlement layer (tantalum) are deposited by magnetron sputtering directly on a substrate; Figure 4 It is a workpiece diagram of Example 2 in which two stress relief layers (chromium) and an anti-hydrogen embrittlement layer (tantalum) are deposited by magnetron sputtering directly on a copper substrate; Figure 5 It is a workpiece diagram of Example 3 in which five stress relief layers (chromium) and an anti-hydrogen embrittlement layer (tantalum) are deposited by magnetron sputtering directly on a copper substrate; Figure 6 It is a workpiece diagram of Example 4 in which twenty stress relief layers (chromium) and an anti-hydrogen embrittlement layer (tantalum) are deposited by magnetron sputtering directly on a copper substrate.

[0033] The reference numerals in the drawings are: substrate 1, stress relief layer 2, anti-hydrogen embrittlement layer 3, and functional layer 4. Detailed implementation manners

[0034] The present invention will be further described below in conjunction with examples.

[0035] General example A composite intermediate layer of an accelerator neutron source target system, as Figure 1 shown, is located between the functional layer 4 and the substrate 1 (heat conducting layer) of the accelerator neutron source target system, and includes at least one stress relief layer 2 and at least one anti-hydrogen embrittlement layer 3 that are alternately laminated; The stress relief layer located at the bottommost layer is provided on the upper surface of the substrate, and the anti-hydrogen embrittlement layer located at the topmost layer is provided on the lower surface of the functional layer; The deviation of the coefficient of thermal expansion of each anti-hydrogen embrittlement layer relative to the stress relief layer adjacent to its lower surface is ≤ 30%, and can be expressed by the following formula:: In the formula: α is the coefficient of thermal expansion of the corresponding layer, with the unit of 1 / °C.

[0036] In some specific embodiments, the thickness of a single stress relief layer is ≤ 1 μm, and more preferably ≤ 0.05 μm.

[0037] In some specific embodiments, the thickness of a single anti-hydrogen embrittlement layer is preferably 0.2 - 2 μm, and more preferably 0.8 - 1.2 μm.

[0038] In some specific embodiments, the number of layers of both the stress relief layer and the anti-hydrogen embrittlement layer is n, and n = the total required thickness of the anti-hydrogen embrittlement layer / the thickness of a single anti-hydrogen embrittlement layer.

[0039] In some specific embodiments, the material of the stress relief layer is selected from one or more of chromium, titanium, zirconium, zinc, silicon, boron, and their carbides and nitrides.

[0040] In some specific embodiments, the material of the hydrogen embrittlement resistant layer is selected from one or more of tantalum, vanadium, palladium, niobium, platinum, tungsten, and their corresponding oxides.

[0041] Further preferably, the material of the stress relief layer is chromium and the material of the hydrogen embrittlement resistant layer is tantalum; or the material of the stress relief layer is titanium and the material of the hydrogen embrittlement resistant layer is tantalum; or the material of the stress relief layer is zirconium and the material of the hydrogen embrittlement resistant layer is tantalum; or the material of the stress relief layer is chromium and the material of the hydrogen embrittlement resistant layer is niobium; or the material of the stress relief layer is titanium and the material of the hydrogen embrittlement resistant layer is niobium.

[0042] In some specific embodiments, the materials of each stress relief layer or hydrogen embrittlement resistant layer are the same or different.

[0043] A method for preparing a composite intermediate layer of the above accelerator neutron source target system includes the following steps: S1: Deposit the bottommost stress relief layer on the upper surface of the substrate; S2: Deposit the bottommost hydrogen embrittlement resistant layer on the upper surface of the stress relief layer obtained in the previous step; S3: According to requirements, on the basis of S2, sequentially deposit the remaining stress relief layers and hydrogen embrittlement resistant layers.

[0044] In some specific embodiments, the deposition method is physical vapor deposition, chemical vapor deposition, solution spin coating, dipping, spraying, electrochemical deposition, gel method, or molecular beam epitaxy.

[0045] In some specific embodiments, each stress relief layer or hydrogen embrittlement resistant layer adopts the same or different deposition methods.

[0046] In some specific embodiments, the substrate is pre-treated by surface cleaning to remove surface impurities and oil stains, and further preferably polishing, ultrasonic cleaning, drying, etc.

[0047] An accelerator neutron source target system includes: Substrate 1; A composite intermediate layer provided on the upper surface of the substrate (including at least one stress relief layer 2 and at least one hydrogen embrittlement resistant layer 3); A functional layer 4 provided on the upper surface of the composite intermediate layer; A protective layer covering the outer surfaces of the functional layer and the composite intermediate layer.

[0048] In some specific embodiments, the material of the substrate is selected from copper.

[0049] In some specific embodiments, the material of the functional layer is selected from lithium and beryllium.

[0050] In some specific embodiments, the material of the protective layer is selected from titanium and chromium.

[0051] Specific embodiments and comparative examples Comparative Example 1 (without stress relief layer) Using oxygen-free copper as the substrate (thermal conduction layer) material, it is polished successively, ultrasonically cleaned with ultrapure water and acetone as media and dried; the substrate is installed on the workpiece holder of the magnetron sputtering coating machine, placed in the chamber of the magnetron sputtering coating machine, and evacuated to below 8×10 -4 Pa; 20 SCCM of argon gas is introduced into the chamber, the sputtering gas pressure is controlled at 0.5 Pa, and the workpiece holder is moved to the position where the tantalum target is located; the tantalum target power is set at 300 W, and tantalum is sputtered on the substrate for 1 hour; after the sputtering process is completed, the air pressure inside and outside the chamber is balanced, and the substrate deposited with a hydrogen embrittlement resistant layer (thickness 1 micron) made of tantalum is taken out.

[0052] The surface effect of this case is as Figure 2 shown. Due to the poor bonding force between copper and tantalum, the surface is rough, with wrinkles and even peeling occurring in many places.

[0053] Example 1 (single-layer stress relief layer and single-layer hydrogen embrittlement resistant layer) Using oxygen-free copper as the substrate (thermal conduction layer) material, it is polished successively, ultrasonically cleaned with ultrapure water and acetone as media and dried; the substrate is installed on the workpiece holder of the magnetron sputtering coating machine, placed in the chamber of the magnetron sputtering coating machine, and evacuated to below 8×10 -4 Pa; 20 SCCM of argon gas is introduced into the chamber, the sputtering gas pressure is controlled at 0.5 Pa, and the workpiece holder is moved to the position where the chromium target is located; the tantalum target power is set at 300 W, and chromium is sputtered on the copper substrate for 10 minutes; after the chromium sputtering process is completed, the power supply of the chromium target is turned off, and the workpiece holder is moved to the position where the tantalum target is located; the tantalum target power is set at 300 W, and tantalum is sputtered on the substrate for 1 hour; after the sputtering process is completed, the air pressure inside and outside the chamber is balanced, and the substrate deposited successively with a stress relief layer made of chromium and a hydrogen embrittlement resistant layer made of tantalum is taken out.

[0054] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes a stress relief layer and a hydrogen embrittlement resistant layer; the thickness of the single-layer stress relief layer is 40 nm; the thickness of the single-layer hydrogen embrittlement resistant layer is 1 micron; the thermal expansion coefficient of the stress relief layer (Cr, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface satisfies the following relationship: Its surface effect is asFigure 3 As shown, compared with directly depositing tantalum on copper, the surface of the deposited tantalum is smoother and more uniform after adding a chromium stress relief layer.

[0055] Example 2 (2 stress relief layers and 2 hydrogen embrittlement resistant layers) On the basis of Example 1, the substrate on which a layer of chromium and a layer of tantalum have been deposited respectively is installed on the workpiece holder of the magnetron sputtering coating machine again, placed in the chamber of the magnetron sputtering coating machine, and evacuated to below 8×10 -4 Pa; 20 SCCM of argon gas is introduced into the chamber, the sputtering pressure is controlled at 0.5 Pa, and the workpiece holder is moved to the position where the chromium target is located; the power of the tantalum target is set at 300 W, and chromium is sputtered on the copper substrate for 10 minutes; after the chromium sputtering process is completed, the power supply of the chromium target is turned off, and the workpiece holder is moved to the position where the tantalum target is located; the power of the tantalum target is set at 300 W, and tantalum is sputtered on the substrate for 1 hour; after the sputtering process is completed, the air pressure inside and outside the chamber is balanced, and the substrate on which two stress relief layers and hydrogen embrittlement resistant layers are deposited alternately is taken out.

[0056] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 2 stress relief layers and 2 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 40 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 micron; the thermal expansion coefficient of the stress relief layer (Cr, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface satisfies the following relationship: Its surface effect is as Figure 4 shown, and its surface is still relatively smooth and uniform.

[0057] Example 3 (5 stress relief layers and 5 hydrogen embrittlement resistant layers) Using oxygen-free copper as the substrate (thermal conduction layer) material, it is polished, ultrasonically cleaned with ultrapure water and acetone as media and dried in sequence; the copper substrate is installed on the workpiece holder of the magnetron sputtering coating machine, placed in the chamber of the magnetron sputtering coating machine, and evacuated to below 8×10 -4 Pa; 20 SCCM of argon gas is introduced into the chamber, the sputtering pressure is controlled at 0.5 Pa, and the workpiece holder is moved to the position where the chromium target is located; the power of the tantalum target is set at 300 W, and chromium is sputtered on the copper substrate for 10 min; after the chromium sputtering process is completed, the power supply of the chromium target is turned off, and the workpiece holder is moved to the position where the tantalum target is located; the power of the tantalum target is set at 300 W, and tantalum is sputtered on the copper substrate for 1 h. The process of sputtering chromium for 10 min and tantalum for 1 h is repeated 5 times.

[0058] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 40 nm, and the total thickness is about 200 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 micron, and the total thickness is about 5 μm; the thermal expansion coefficient of the stress relief layer (Cr, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface satisfies the following relationship: Its surface effect is as Figure 5 shown, and its surface is still relatively smooth and uniform.

[0059] Example 4 (20 stress relief layers and 20 hydrogen embrittlement resistant layers) Using oxygen-free copper as the substrate (heat conducting layer) material, it is polished, ultrasonically cleaned with ultrapure water and acetone as the media and dried in sequence; the copper substrate is installed on the workpiece holder of the magnetron sputtering coating machine, placed in the chamber of the magnetron sputtering coating machine, and evacuated to below 8×10-4 Pa; 20 SCCM of argon gas is introduced into the chamber, the sputtering gas pressure is controlled at 0.5 Pa, and the workpiece holder is moved to the position where the chromium target is located; the tantalum target power is set at 300 W, and chromium is sputtered on the copper substrate for 10 min; after the chromium sputtering process is completed, the power supply of the chromium target is turned off, and the workpiece holder is moved to the position where the tantalum target is located; the tantalum target power is set at 300 W, and tantalum is sputtered on the copper substrate for 1 h. To make the tantalum layer reach the target thickness (20 μm), the process of sputtering chromium for 10 min and tantalum for 1 h is cycled 20 times.

[0060] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 20 stress relief layers and 20 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 40 nm, and the total thickness is about 800 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 micron, and the total thickness is about 20 μm; the thermal expansion coefficient of the stress relief layer (Cr, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface satisfies the following relationship: Its surface effect is as Figure 6 shown, and its surface is still relatively smooth and uniform.

[0061] Example 5 (The difference from Example 3 is that the thickness of a single stress relief layer is different) Using oxygen-free copper as the substrate (heat conducting layer) material, it is polished, ultrasonically cleaned with ultrapure water and acetone as the media and dried in sequence; the copper substrate is installed on the workpiece holder of the magnetron sputtering coating machine, placed in the chamber of the magnetron sputtering coating machine, and evacuated to 8×10 -4Below Pa; Introduce 20 SCCM of argon gas into the chamber, control the sputtering pressure to be 0.5 Pa, and move the workpiece holder to the position where the chromium target is located; Set the tantalum target power to 300 W, and sputter chromium on the copper substrate for 10 min; After the chromium sputtering process is completed, turn off the power supply of the chromium target, and move the workpiece holder to the position where the tantalum target is located; Set the tantalum target power to 300 W, and sputter tantalum on the copper substrate for 1 h. Cycle the process of sputtering chromium for 30 min and tantalum for 1 h 5 times.

[0062] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; The thickness of a single stress relief layer is 120 nm, and the total thickness is about 600 nm; The thickness of a single hydrogen embrittlement resistant layer is 1 micron, and the total thickness is about 5 μm; The stress relief layer (Cr, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface have the following relationship for the coefficient of thermal expansion: Comparative Example 2 (the difference from Example 3 is that the thickness of a single stress relief layer > 1 micron) Use oxygen-free copper as the substrate (thermal conduction layer) material, and perform polishing, ultrasonic cleaning with ultrapure water and acetone as the medium, and drying in sequence; Install the copper substrate on the workpiece holder of the magnetron sputtering coating machine, put it into the chamber of the magnetron sputtering coating machine, and evacuate to 8×10 -4 Below Pa; Introduce 20 SCCM of argon gas into the chamber, control the sputtering pressure to be 0.5 Pa, and move the workpiece holder to the position where the chromium target is located; Set the tantalum target power to 300 W, and sputter chromium on the copper substrate for 10 min; After the chromium sputtering process is completed, turn off the power supply of the chromium target, and move the workpiece holder to the position where the tantalum target is located; Set the tantalum target power to 300 W, and sputter tantalum on the copper substrate for 1 h. Cycle the process of sputtering chromium for 5 h and tantalum for 1 h 5 times.

[0063] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; The thickness of a single stress relief layer is 1.2 μm, and the total thickness is about 6 μm; The thickness of a single hydrogen embrittlement resistant layer is 1 micron, and the total thickness is about 5 μm; The stress relief layer (Cr, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface have the following relationship for the coefficient of thermal expansion: Comparative Example 3 (the difference from Example 3 is that the material of the stress relief layer is iron) Using oxygen-free copper as the substrate (thermal conduction layer) material, polish it successively, and perform ultrasonic cleaning with ultrapure water and acetone as media and then dry it; install the copper substrate on the workpiece holder of the magnetron sputtering coating machine, put it into the chamber of the magnetron sputtering coating machine, and evacuate to below 8×10 -4 Pa; introduce 20 SCCM of argon gas into the chamber, control the sputtering gas pressure to 0.5 Pa, and move the workpiece holder to the position where the iron target is located; set the tantalum target power to 300 W, and sputter iron on the copper substrate for 10 min; after the iron sputtering process is completed, turn off the power supply of the iron target, and move the workpiece holder to the position where the tantalum target is located; set the tantalum target power to 300 W, and sputter tantalum on the copper substrate for 1 h. Repeat the process of sputtering iron for 10 min and tantalum for 1 h 5 times.

[0064] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 30 nm, and the total thickness is about 150 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 μm, and the total thickness is about 5 μm; the thermal expansion coefficient of the stress relief layer (Fe, 1.17×10 -5 / K) and the adjacent hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) on its upper surface satisfies the following relationship: Comparative Example 4 (the difference from Example 3 is that the stress relief layer material is nickel) Using oxygen-free copper as the substrate (thermal conduction layer) material, polish it successively, and perform ultrasonic cleaning with ultrapure water and acetone as media and then dry it; install the copper substrate on the workpiece holder of the magnetron sputtering coating machine, put it into the chamber of the magnetron sputtering coating machine, and evacuate to below 8×10 -4 Pa; introduce 20 SCCM of argon gas into the chamber, control the sputtering gas pressure to 0.5 Pa, and move the workpiece holder to the position where the nickel target is located; set the tantalum target power to 300 W, and sputter nickel on the copper substrate for 10 min; after the nickel sputtering process is completed, turn off the power supply of the nickel target, and move the workpiece holder to the position where the tantalum target is located; set the tantalum target power to 300 W, and sputter tantalum on the copper substrate for 1 h. Repeat the process of sputtering nickel for 10 min and tantalum for 1 h 5 times.

[0065] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 35 nm, and the total thickness is about 175 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 μm, and the total thickness is about 5 μm; the thermal expansion coefficient of the stress relief layer (Ni, 1.34×10 -5 / K) and the adjacent hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) on its upper surface satisfies the following relationship: Example 6 (The difference from Example 3 is that the stress relief layer material is titanium) Using oxygen-free copper as the substrate (thermal conduction layer) material, perform polishing, ultrasonic cleaning with ultrapure water and acetone as the media, and drying in sequence; install the copper substrate on the workpiece holder of the magnetron sputtering coating machine, place it in the chamber of the magnetron sputtering coating machine, and evacuate to below 8×10 -4 Pa; introduce 20 SCCM of argon gas into the chamber, control the sputtering pressure to be 0.5 Pa, and move the workpiece holder to the position where the titanium target is located; set the tantalum target power to 300 W, and sputter titanium on the copper substrate for 10 min; after the titanium sputtering process is completed, turn off the power supply of the titanium target, and move the workpiece holder to the position where the tantalum target is located; set the tantalum target power to 300 W, and sputter tantalum on the copper substrate for 1 h. Repeat the process of sputtering titanium for 10 min and tantalum for 1 h 5 times.

[0066] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 38 nm, and the total thickness is about 190 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 μm, and the total thickness is about 5 μm; the thermal expansion coefficient of the stress relief layer (Ti, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface satisfies the following relationship: Example 7 (The difference from Example 3 is that the stress relief layer material is zirconium) Using oxygen-free copper as the substrate (thermal conduction layer) material, perform polishing, ultrasonic cleaning with ultrapure water and acetone as the media, and drying in sequence; install the copper substrate on the workpiece holder of the magnetron sputtering coating machine, place it in the chamber of the magnetron sputtering coating machine, and evacuate to below 8×10 -4 Pa; introduce 20 SCCM of argon gas into the chamber, control the sputtering pressure to be 0.5 Pa, and move the workpiece holder to the position where the zirconium target is located; set the tantalum target power to 300 W, and sputter zirconium on the copper substrate for 10 min; after the zirconium sputtering process is completed, turn off the power supply of the zirconium target, and move the workpiece holder to the position where the tantalum target is located; set the tantalum target power to 300 W, and sputter tantalum on the copper substrate for 1 h. Repeat the process of sputtering zirconium for 10 min and tantalum for 1 h 5 times.

[0067] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 28 nm, and the total thickness is about 140 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 μm, and the total thickness is about 5 μm; the thermal expansion coefficient of the stress relief layer (Zr, 5.5×10 -6 / K) and the hydrogen embrittlement resistant layer (Ta, 6.3×10 -6 / K) adjacent to its upper surface satisfies the following relationship: Example 8 (The difference from Example 3 is that the stress relief layer material is titanium and the hydrogen embrittlement resistant layer material is niobium) Using oxygen-free copper as the substrate (heat conduction layer) material, perform polishing, ultrasonic cleaning with ultrapure water and acetone as the media, and drying in sequence; install the copper substrate on the workpiece holder of the magnetron sputtering coating machine, place it in the chamber of the magnetron sputtering coating machine, and evacuate to below 8×10 -4 Pa; introduce 20 SCCM of argon gas into the chamber, control the sputtering pressure to be 0.5 Pa, and move the workpiece holder to the position where the titanium target is located; set the niobium target power to 300 W, and sputter titanium on the copper substrate for 10 min; after the titanium sputtering process is completed, turn off the power supply of the titanium target, and move the workpiece holder to the position where the niobium target is located; set the niobium target power to 300 W, and sputter niobium on the copper substrate for 1 h. Cycle the sputtering of titanium for 10 min and the niobium process 5 times.

[0068] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 38 nm, and the total thickness is about 190 nm; the thickness of a single hydrogen embrittlement resistant layer is 0.8 microns, and the total thickness is about 4 μm; the thermal expansion coefficient of the stress relief layer (Ti, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Nb, 7.2×10 -6 / K) adjacent to its upper surface satisfies the following relationship: Example 9 (The difference from Example 3 is that the hydrogen embrittlement resistant layer material is niobium) Using oxygen-free copper as the substrate (heat conduction layer) material, perform polishing, ultrasonic cleaning with ultrapure water and acetone as the media, and drying in sequence; install the copper substrate on the workpiece holder of the magnetron sputtering coating machine, place it in the chamber of the magnetron sputtering coating machine, and evacuate to below 8×10 -4 Pa; introduce 20 SCCM of argon gas into the chamber, control the sputtering pressure to be 0.5 Pa, and move the workpiece holder to the position where the chromium target is located; set the niobium target power to 300 W, and sputter chromium on the copper substrate for 10 min; after the chromium sputtering process is completed, turn off the power supply of the chromium target, and move the workpiece holder to the position where the niobium target is located; set the niobium target power to 300 W, and sputter niobium on the copper substrate for 1 h. Cycle the sputtering of chromium for 10 min and the niobium process 5 times.

[0069] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 5 stress relief layers and 5 hydrogen embrittlement resistant layers; the thickness of a single stress relief layer is 40 nm, and the total thickness is about 200 nm; the thickness of a single hydrogen embrittlement resistant layer is 0.8 microns, and the total thickness is about 4 μm; the thermal expansion coefficient of the stress relief layer (Cr, 8.6×10 -6 / K), the hydrogen embrittlement resistant layer (Nb, 7.2×10 -6 / K) has a thermal expansion coefficient that satisfies the following relationship: Example 10 (different from Example 2 in that two different stress relief layer materials and two different hydrogen embrittlement resistant layer materials are used) uses oxygen-free copper as the substrate (thermal conductive layer) material, and successively performs polishing, ultrasonic cleaning with ultrapure water and acetone as the medium, and drying; installs the copper substrate on the workpiece holder of the magnetron sputtering coating machine, places it in the chamber of the magnetron sputtering coating machine, and evacuates to below 8×10 -4 Pa; introduces 20 SCCM of argon gas into the chamber, controls the sputtering pressure to 0.5 Pa, and moves the workpiece holder to the position where the chromium target is located; sets the tantalum target power to 300 W and sputters chromium on the copper substrate for 10 min; after the chromium sputtering process ends, turns off the power supply of the chromium target, and moves the workpiece holder to the position where the tantalum target is located; sets the tantalum target power to 300 W and sputters tantalum on the copper substrate for 1 h. After the tantalum sputtering process ends, turns off the power supply of the tantalum target, and moves the workpiece holder to the position where the nickel target is located; sets the nickel target power to 300 W and sputters nickel for 10 min; after the nickel sputtering process ends, turns off the power supply of the nickel target, and moves the workpiece holder to the position where the niobium target is located; sets the niobium target power to 300 W and sputters niobium for 1 h.

[0070] The composite intermediate layer formed by deposition on the upper surface of the substrate in this case includes 2 layers of stress relief layers (chromium, nickel) and 2 layers of hydrogen embrittlement resistant layers (tantalum, niobium); the thickness of a single layer of chromium stress relief layer is 40 nm, the thickness of a single layer of nickel stress relief layer is 35 nm, and the total thickness is about 75 nm; the thickness of a single layer of tantalum hydrogen embrittlement resistant layer is 1 micron, the thickness of a single layer of niobium hydrogen embrittlement resistant layer is 0.8 micron, and the total thickness is about 1.8 μm.

[0071] Performance Test The stress indexes of the composite films obtained in each example and the comparative example are shown in the following table: In Comparative Example 1, due to the absence of a stress relief layer, the film stress accumulated too high, reaching 31.73 GPa, and film rupture occurred in the 1-micron hydrogen embrittlement resistant layer.

[0072] After adding 1 layer of chromium stress relief layer in Example 1, compared with Comparative Example 1, the film stress was reduced to 13.59 GPa, and the deposition of the 1-micron hydrogen embrittlement resistant layer was achieved.

[0073] After adding two chromium stress relief layers in Example 2, compared with Comparative Example 1, the film stress was reduced to 13.86 GPa, and the deposition of a 2-μm hydrogen embrittlement resistant layer was achieved. After adding five chromium stress relief layers in Example 3, the film stress was reduced to 13.01 GPa, and the deposition of a 5-μm hydrogen embrittlement resistant layer was achieved.

[0074] After adding twenty chromium stress relief layers in Example 4, compared with Comparative Example 1, the film stress was reduced to 12.33 GPa, and the deposition of a 20-μm hydrogen embrittlement resistant layer was achieved.

[0075] In Example 5, the thickness of a single chromium stress relief layer was set to 120 nm (meeting the thickness range), and the total thickness of the stress relief layers was 600 nm. Compared with Comparative Example 1, the film stress was reduced to 12.97 GPa, and the deposition of a 5-μm hydrogen embrittlement resistant layer was achieved.

[0076] In Example 6, titanium was used as the stress relief layer and tantalum was used as the hydrogen embrittlement resistant layer. The thermal expansion coefficients of the two met the formula requirements, and the film stress (12.13 GPa) was appropriate, resulting in good deposition effect.

[0077] In Example 7, zirconium was used as the stress relief layer and tantalum was used as the hydrogen embrittlement resistant layer. The thermal expansion coefficients of the two met the formula requirements, and the film stress (12.58 GPa) was appropriate, resulting in good deposition effect.

[0078] In Example 8, titanium was used as the stress relief layer and niobium was used as the hydrogen embrittlement resistant layer. As a preferred combination, the thermal expansion coefficients of the two met the formula requirements, and the film stress (11.79 GPa) was appropriate, resulting in good deposition effect.

[0079] In Example 9, chromium was used as the stress relief layer and niobium was used as the hydrogen embrittlement resistant layer. As a preferred combination, the thermal expansion coefficients of the two met the formula requirements, and the film stress (12.33 GPa) was appropriate, resulting in good deposition effect.

[0080] In Example 10, two stress relief layers (chromium, nickel) and two hydrogen embrittlement resistant layers (tantalum, niobium) were sequentially set. The thermal expansion coefficients of all met the formula requirements, and the film stress (12.03 GPa) was appropriate, resulting in good deposition effect.

[0081] In Comparative Example 2, when the thickness of a single chromium stress relief layer did not meet the highest requirement (the single stress relief layer was greater than 1 μm), compared with Comparative Example 1, the film stress decreased slightly, but was still more than twice as high as that of Example 3, resulting in a deposition effect inferior to that of Example 3 but still better than that of Comparative Example 1.

[0082] In Comparative Example 3, iron was used as the stress relief layer and tantalum was used as the hydrogen embrittlement resistant layer, but the thermal expansion coefficients of the two did not meet the formula requirements, resulting in a film stress higher than that of Example 3 and a poor deposition effect.

[0083] In Comparative Example 4, nickel was used as the stress relief layer and tantalum was used as the hydrogen embrittlement resistant layer. However, their thermal expansion coefficients did not meet the formula requirements, resulting in a higher film stress (21.38 GPa) than that in Example 3 and poor deposition effect.

[0084] As shown by the above results, in each of the examples, the film stress range was 11.79 - 13.86 GPa, corresponding to the deposition of a high-quality hydrogen embrittlement resistant layer.

[0085] Application Example 1 An accelerator neutron source target system, comprising: Substrate 1; A composite intermediate layer (Example 1) provided on the upper surface of the substrate; A functional layer 4 (lithium) provided on the upper surface of the composite intermediate layer; A protective layer (titanium) covering the outer surfaces of the functional layer and the composite intermediate layer.

[0086] Application Example 2 An accelerator neutron source target system, comprising: Substrate 1; A composite intermediate layer (Example 2) provided on the upper surface of the substrate; A functional layer 4 (lithium) provided on the upper surface of the composite intermediate layer; A protective layer (chromium) covering the outer surfaces of the functional layer and the composite intermediate layer.

[0087] Application Example 3 An accelerator neutron source target system, comprising: Substrate 1; A composite intermediate layer (Example 3) provided on the upper surface of the substrate; A functional layer 4 (beryllium) provided on the upper surface of the composite intermediate layer; A protective layer (titanium) covering the outer surfaces of the functional layer and the composite intermediate layer.

[0088] The raw materials and equipment used in the present invention are, unless otherwise specified, common raw materials and equipment in the art; the methods used in the present invention are, unless otherwise specified, conventional methods in the art.

[0089] The above are only the preferred embodiments of the present invention and do not impose any limitation on the present invention. Any simple modification, change, and equivalent transformation made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A composite intermediate layer of an accelerator neutron source target system, characterized in that: Located between the active layer and the substrate of the accelerator neutron source target system, it includes at least one layer of stress relief layer and at least one layer of hydrogen embrittlement resistance layer which are staggered and stacked; The stress relief layer at the bottom layer is arranged on the upper surface of the substrate, and the anti-hydrogen embrittlement layer at the top layer is arranged on the lower surface of the active layer; The deviation of the thermal expansion coefficient of each of the anti-hydrogen embrittlement layers relative to the stress relief layer adjacent to its lower surface is ≤30%.

2. The composite intermediate layer of the accelerator neutron source target system according to claim 1, characterized in that: The thickness of the single layer of stress relief layer is ≤ 1 micron; and / or The thickness of the single-layer hydrogen embrittlement-resistant layer is 0.5-2 microns.

3. The composite intermediate layer of the accelerator neutron source target system according to claim 2, characterized in that: The number of layers of the stress relief layer and the anti-hydrogen embrittlement layer is n, where n=the total thickness of the anti-hydrogen embrittlement layer required theoretically / the thickness of a single anti-hydrogen embrittlement layer.

4. The composite intermediate layer of the accelerator neutron source target system according to any one of claims 1 to 3, characterized in that: The material of the stress relief layer is selected from one or more of chromium, titanium, zirconium, zinc, silicon, boron and carbides and nitrides thereof; or The material of the hydrogen embrittlement resistant layer is selected from one or more of tantalum, vanadium, palladium, niobium, platinum, tungsten and oxides thereof.

5. The composite intermediate layer of the accelerator neutron source target system according to claim 4, characterized in that: The material of the stress relief layer is chromium, and the material of the anti-hydrogen embrittlement layer is tantalum; or The material of the stress relief layer is titanium, and the material of the anti-hydrogen embrittlement layer is tantalum; or The material of the stress relief layer is zirconium, and the material of the anti-hydrogen embrittlement layer is tantalum; or The material of the stress relief layer is chromium, and the material of the anti-hydrogen embrittlement layer is niobium; or The material of the stress relief layer is titanium, and the material of the anti-hydrogen embrittlement layer is niobium.

6. The composite intermediate layer of the accelerator neutron source target system according to claim 4, characterized in that: The materials of each stress relief layer or hydrogen embrittlement resistance layer are the same or different.

7. A method for preparing a composite intermediate layer of an accelerator neutron source target system according to any one of claims 1 to 6, characterized in that The following steps are involved: S1: depositing the bottom stress relief layer on the upper surface of the substrate; S2: depositing the bottommost anti-hydrogen embrittlement layer on the upper surface of the stress relief layer obtained in the previous step; S3: Based on S2, the remaining stress relief layers and anti-hydrogen embrittlement layers are deposited in sequence as needed.

8. The preparation method according to claim 7, characterized in that: The deposition method is physical vapor deposition, chemical vapor deposition, solution spin coating, dipping, spraying, electrochemical deposition, gel method or molecular beam epitaxy.

9. The preparation method according to claim 8, characterized in that: Each stress relief layer or hydrogen embrittlement resistance layer is deposited in the same or different manners.

10. Use of the composite intermediate layer according to any one of claims 1 to 6 or the composite intermediate layer obtained by the preparation method according to any one of claims 7 to 9 in an accelerator neutron source target system, characterized in that: The accelerator neutron source target system comprises: substrate; The composite intermediate layer is disposed on the upper surface of the substrate; An active layer is arranged on the upper surface of the composite intermediate layer.

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