Neutron source target substrate surface structure and its laser surface treatment construction method

Abstract

The application relates to the field of medical devices and discloses a neutron source target substrate surface structure and a laser surface treatment construction method thereof. The surface of the substrate is provided with parallel corrugated grooves; the surface of the parallel grooves is distributed with holes. The construction method comprises the following steps: laser surface treatment is performed on the neutron source target substrate by using a laser; wherein: a parallel laser scanning mode is adopted, the laser power is 0-20 W, the pulse duration is 0-100 ns, the laser line spacing is 5-30 mu m, and the scanning speed is 10-1000 mm / s; and a neutron source target substrate with surface topography characteristics is obtained after treatment. Through laser surface treatment on the neutron source target substrate, the microtopography, roughness and film crystallinity of the surface of the neutron source target substrate can be regulated, thereby providing favorable conditions for further constructing a target material intermediate layer with high film coating effect on the surface.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and in particular to a surface structure of a neutron source target substrate and a method for constructing it using laser surface treatment. Background Technology

[0002] In the fabrication of accelerator neutron source targets, a layer of material first needs to be introduced onto the substrate to mitigate hydrogen embrittlement caused by hydrogen bubbling after protons have completely stopped accumulating. Currently, commonly used methods for depositing anti-hydrogen embrittlement layer materials include thermal spraying, physical vapor deposition (PVD), and chemical vapor deposition (CVD). If the anti-hydrogen bubbling layer material is directly deposited on the substrate using these methods, the adhesion between the coating layer and the substrate will be weak due to the oxide layer, impurities, and surface smoothness of the substrate, making it prone to peeling or detachment. Therefore, surface treatment of the substrate is required before coating to improve the coating effect of the neutron source target's anti-hydrogen embrittlement layer.

[0003] Currently, commonly used material surface treatment methods include mechanical polishing, chemical etching, and laser treatment, each with its own advantages and disadvantages. For example, mechanical polishing has the advantage of low equipment requirements, but its disadvantages include long processing time and the inability to guarantee surface uniformity. Chemical etching has the advantage of simple operation, but its disadvantages include the potential for excessive corrosion or damage to the substrate, and the need to use toxic or corrosive chemicals, posing certain risks to the environment and operators. Laser surface treatment has the advantages of high precision and high efficiency, but its disadvantages include the potential for significant internal stress in the substrate due to rapid heating and cooling of the workpiece surface, which may lead to the formation and propagation of cracks in subsequent thin films.

[0004] In existing technologies, researchers often focus only on the surface roughness or specific surface area of ​​the substrate after surface treatment, rarely considering the impact of substrate surface morphology on subsequent coating. Our team has discovered that, compared to other substrates requiring coating, substrates used as neutron source targets have specific requirements for surface morphology in addition to meeting certain surface roughness requirements to increase specific surface area. Our preliminary experiments revealed that constructing a wavy parallel trench microstructure on the substrate surface significantly increases surface roughness (increasing specific surface area) compared to ordinary rough surfaces. More importantly, during subsequent coating, this parallel trench microstructure effectively immobilizes high-energy magnetron sputtered particles, inducing nucleation and thus regulating coating crystallinity. This better enhances the interlayer adhesion between the coating and the substrate. Furthermore, during long-term service of the neutron source target, this structure is more conducive to heat dissipation and micro-area stress relief, extending the target's lifespan.

[0005] Therefore, in order to improve the surface coating effect of the neutron source target substrate, it is necessary to construct the aforementioned specific microstructure on the surface of the neutron source target substrate. However, how to stably and efficiently construct the aforementioned special surface morphology features on the substrate surface using existing surface treatment methods has not been thoroughly studied in the prior art. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a surface structure for a neutron source target substrate and a method for constructing it using laser surface treatment. By performing laser surface treatment on the neutron source target substrate, this invention can control the microstructure, roughness, and crystallinity of the coating on the substrate surface, thereby providing favorable conditions for further constructing a target material intermediate layer with high coating efficiency on its surface.

[0007] The specific technical solution of this invention is as follows: In a first aspect, the present invention provides a surface structure of a neutron source target substrate, wherein the surface of the substrate and the intermediate layer are provided with corrugated parallel trenches; and the surface of the parallel trenches is distributed with micropores.

[0008] Preferably, the width of the parallel trenches is 30-60 micrometers; and the size of the micropores is 5-30 micrometers.

[0009] Secondly, the present invention provides a method for constructing the surface structure of the above-mentioned neutron source target substrate based on laser surface treatment, comprising: using a laser to perform laser surface treatment on the neutron source target substrate, thereby obtaining a neutron source target substrate with special surface morphology characteristics.

[0010] The invention team discovered that, in order to construct a high-quality target intermediate layer, in addition to the surface roughness and specific surface area of ​​the neutron source target substrate, the surface morphology of the neutron source target substrate also has a significant impact. The invention further discovered that constructing a wavy parallel trench microstructure on the substrate surface, compared to a normal rough surface, not only significantly increases surface roughness (increasing specific surface area), but more importantly, during the subsequent coating process, the aforementioned parallel trench microstructure can effectively fix high-energy particles sputtered by magnetron sputtering, inducing nucleation and thus regulating the crystallinity of the coating. Simultaneously, after high-energy particles reach the surface of the parallel trench microstructure, the micropores on its surface can be better filled, thereby better improving the interlayer adhesion between the coating and the substrate. Furthermore, when the neutron source target is in long-term service, this structure is more conducive to heat dissipation and micro-area stress relief, thus extending the target life.

[0011] After numerous trials, we discovered that compared to other surface treatment methods (such as mechanical polishing, chemical etching, bias treatment, etc.), a surface with a highly similar morphology to the above-mentioned special surface can be obtained by treating the surface of the neutron source target substrate with laser processing under the specific conditions of this invention.

[0012] Because the surface after laser processing is a special surface that lies between isotropic and anisotropic, its morphology differs significantly from that of surfaces processed by traditional machining and electrical discharge machining. During laser processing, the laser beam generates high temperatures as it moves across the substrate surface, vaporizing and melting the material. The resulting molten material accumulates along the laser scanning direction, forming parallel, wavy grooves with a width of 30-60 micrometers that follow the laser scanning path. Therefore, this structure is highly similar to the target's microstructure.

[0013] Furthermore, we discovered that this process of high-temperature melting followed by low-temperature solidification generates irregular micropores with dimensions of approximately 5–30 micrometers on the surface of each trench. During subsequent magnetron sputtering, when high-energy particles reach the surface of the parallel trenches, these micropores can be better filled, thereby improving the interlayer adhesion between the coating and the substrate. When the neutron source target is in long-term service, this micropore structure can further facilitate heat dissipation and micro-area stress relief.

[0014] In summary, this invention modulates the microstructure, roughness, and coating crystallinity of the neutron source target substrate surface through laser processing, thereby providing favorable conditions for further constructing a target material intermediate layer with high coating effect on its surface.

[0015] Preferably, a parallel laser scanning method is used, with a laser power of 0-20W, a pulse duration of 0-100ns, a laser line spacing of 5-30μm, and a scanning speed of 10-1000mm / s.

[0016] More preferably, the laser surface treatment adopts a parallel laser scanning method with a laser power of 10-20 W, a pulse duration of 0-80 ns, a laser line spacing of 5-20 μm, and a scanning speed of 50-500 mm / s.

[0017] Through experiments, this invention further discovered that different laser processing conditions have a certain impact on the surface morphology of the neutron source target substrate (including microstructure size and the ability to generate micropores, etc.). Therefore, in order to obtain a substrate surface that more closely resembles the target morphology, this invention preferably and further preferably uses the aforementioned laser processing technology.

[0018] If the laser treatment is insufficient, it will result in an inability to form a sufficient number of micropores on the surface of the trench. Conversely, if the laser treatment is too high, the micropores on the surface will be continuously arranged along the direction of laser movement, forming a surface with a large height difference. Such a surface will have a severe shadowing effect during sputtering, which is not conducive to the subsequent film growth.

[0019] Preferably, the neutron source target substrate is made of copper, vanadium, tungsten, gold, platinum, lead, or an alloy thereof.

[0020] Preferably, the neutron source target substrate undergoes surface pre-cleaning to remove surface impurities and oil stains; more preferably, it is cleaned using organic solvents and deionized water.

[0021] Thirdly, the present invention provides a neutron source target, comprising a substrate, an intermediate layer disposed on the surface of the substrate, and a target material layer disposed on the surface of the intermediate layer, wherein the surface of the substrate and the intermediate layer are provided with corrugated parallel grooves; and the surface of the parallel grooves is distributed with micropores.

[0022] Preferably, the width of the parallel trenches is 30-60 micrometers; and the size of the micropores is 5-30 micrometers.

[0023] Preferably, the intermediate layer is formed by spraying, physical vapor deposition, chemical vapor deposition or electroplating.

[0024] Preferably, the intermediate layer is a hydrogen embrittlement resistant layer or a composite intermediate layer.

[0025] Preferably, the composite intermediate layer includes at least one stress relief layer and at least one hydrogen embrittlement resistant layer that are stacked in an alternating manner; The stress relief layer, located at the bottom layer, is disposed on the upper surface of the substrate, and the hydrogen embrittlement resistant layer, located at the top layer, is disposed on the lower surface of the target material layer.

[0026] Preferably, the deviation of the coefficient of thermal expansion of each of the hydrogen embrittlement-resistant layers relative to the stress-relieving layer adjacent to its lower surface is ≤30%, which can be expressed as:

[0027] In the formula: α is the thermal expansion coefficient of the corresponding layer, in units of 1 / ℃.

[0028] Preferably, the thickness of a single stress-relieving layer is ≤1 micrometer, and more preferably ≤0.05 micrometers.

[0029] Preferably, the thickness of the single-layer hydrogen embrittlement resistant layer is 0.2-2 micrometers, and more preferably 0.8-1.2 micrometers.

[0030] Preferably, the number of stress relief layer and hydrogen embrittlement resistant layer is n, where n = the theoretically required total thickness of the hydrogen embrittlement resistant layer / the thickness of a single hydrogen embrittlement resistant layer.

[0031] 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.

[0032] Preferably, the material of the hydrogen embrittlement resistant layer is selected from one or more of tantalum, vanadium, palladium, niobium, platinum, tungsten, and their oxides. Preferably, the target layer is a lithium target layer or a beryllium target layer.

[0033] Compared with the prior art, the beneficial effects of the present invention are: (1) By performing laser surface treatment on the neutron source target substrate, the present invention can control the microstructure, roughness and coating crystallinity of the neutron source target substrate surface, thereby providing favorable conditions for further constructing a target material intermediate layer with high coating effect on its surface.

[0034] (2) The present invention uses laser processing to pre-treat the surface of the neutron source target substrate. This method is free of toxic chemicals, which can not only reduce environmental pollution and operational risks, but also reduce costs and operational difficulties.

[0035] (3) The present invention further constructs a target material composite intermediate layer on the surface of the neutron source target substrate, which can improve the adhesion, crystallinity, composition uniformity and thermal stability of the original intermediate layer, thereby improving its bonding force with the substrate and solving the problem of easy detachment in the existing intermediate layer preparation process, so as to prepare a high-performance and stable accelerator neutron source target system. Attached Figure Description

[0036] Figure 1 This is a scanning electron microscope image of the substrate surface after the treatment in Example 3; Figure 2 This is a scanning electron microscope image of the substrate after surface treatment in Comparative Example 1; Figure 3 This is a scanning electron microscope image of the substrate after surface treatment in Comparative Example 2; Figure 4 This is a scanning electron microscope image of the substrate after surface treatment in Comparative Example 3; Figure 5 These are photos of the substrates after coating in each case study; Figure 6 These are scanning electron microscope images of the blank group substrate after coating; Figure 7 This is a copper element distribution diagram after coating on the blank group substrate; Figure 8 This is a tantalum element distribution diagram after coating on the blank group substrate; Figure 9 This is a copper element distribution diagram after the substrate of Example 3 was coated; Figure 10 This is a tantalum element distribution diagram after the substrate of Example 3 has been coated. Detailed Implementation

[0037] The present invention will be further described below with reference to embodiments.

[0038] General Implementation Examples A method for constructing a surface structure of a neutron source target substrate based on laser surface treatment includes: performing laser surface treatment on the neutron source target substrate using a laser; wherein: a parallel laser scanning method is used, with a laser power of 0-20W, a pulse duration of 0-100ns, a laser line spacing of 5-30μm, and a scanning speed of 10-1000mm / s; after treatment, a neutron source target substrate with a wavy arrangement of parallel trench microstructures (preferably with a width of about 30-60 micrometers) and irregular micropores (preferably about 5-30 micrometers) on the trench surface is obtained.

[0039] In some more preferred embodiments, the laser surface treatment employs a parallel laser scanning method with a laser power of 10-20W, a pulse duration of 0-80ns, a laser line spacing of 5-20μm, and a scanning speed of 50-500mm / s.

[0040] In some specific embodiments, the neutron source target substrate is made of copper, vanadium, tungsten, gold, platinum, lead, or alloys thereof.

[0041] In some specific embodiments, the neutron source target substrate undergoes surface pre-cleaning to remove surface impurities and oil stains; more preferably, organic solvents and deionized water are used for cleaning.

[0042] In some specific implementations, the intermediate layer is applied by spraying, physical vapor deposition, chemical vapor deposition, or electroplating.

[0043] A neutron source target includes a substrate, an intermediate layer disposed on the surface of the substrate, and a target material layer disposed on the surface of the intermediate layer. The surface where the substrate and the intermediate layer are bonded is provided with corrugated parallel trenches (preferably with a width of about 30 to 60 micrometers). Micropores (preferably with a size of about 5 to 30 micrometers) are distributed on the surface of the parallel trenches.

[0044] In some specific embodiments, the intermediate layer is a hydrogen embrittlement resistant layer or a composite intermediate layer.

[0045] In some specific embodiments, the composite intermediate layer includes at least one stress relief layer and at least one hydrogen embrittlement resistant layer that are stacked in an alternating manner; the stress relief layer at the bottom layer is disposed on the upper surface of the substrate, and the hydrogen embrittlement resistant layer at the top layer is disposed on the lower surface of the target layer.

[0046] Unlike another scheme in this invention (where the intermediate layer is a relatively thick single hydrogen embrittlement resistant layer), this scheme designs the intermediate layer as a composite intermediate layer. Specifically, the original intermediate layer is broken down 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. The introduction of the stress relief layer forms an interface layer that can improve the adhesion, crystallinity, compositional uniformity, and thermal stability of the intermediate layer, thereby enhancing the bonding force between the intermediate layer and the substrate. This solves the problem of easy detachment during existing intermediate layer fabrication processes, enabling the fabrication of high-performance and stable accelerator neutron source target systems.

[0047] The principle behind this invention, which designs the intermediate layer as at least one stress-relief layer and at least one hydrogen embrittlement-resistant layer in a staggered stack, is as follows: First, the original thick single-layer hydrogen embrittlement-resistant layer is broken down into multiple thinner layers. During processing using methods such as vapor deposition, this mitigates the technical problem of intermediate layer peeling caused by insufficient bonding strength due to thermal stress, poor interface, or other factors generated during deposition. Furthermore, it reduces residual stress caused by uneven distribution of internal material stress due to thermal expansion and cooling during the preparation of a thicker intermediate layer, thereby preventing deformation, cracking, or failure of the intermediate layer. Second, the introduction of the stress-relief layer and the use of a staggered stacking method, due to the difference in material properties between the stress-relief layer and the hydrogen embrittlement-resistant layer, can alleviate the accumulation of thermal stress when a single material is deposited to a certain thickness, making the growth process of the hydrogen embrittlement-resistant layer more stable and reducing the risk of stress concentration and cracking.

[0048] In some specific embodiments, the coefficients of thermal expansion of each stress-relieving layer and its adjacent hydrogen embrittlement-resistant layer satisfy the following relationship:

[0049] In the formula: α is the thermal expansion coefficient of the corresponding layer, in units of 1 / ℃.

[0050] This invention reveals that the coefficient of thermal expansion is the primary factor leading to stress accumulation during thin film deposition. Therefore, controlling the coefficients of thermal expansion between adjacent layers within the aforementioned specific range is crucial. If the difference in coefficients exceeds this range, uneven stress distribution will result, leading to film rupture. Furthermore, since the deposited hydrogen embrittlement resistant layer material grows on the upper surface of the stress-relief layer, a good bond 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 the coefficient of thermal expansion between the hydrogen embrittlement resistant layer and the stress-relief layer adjacent to its lower surface to satisfy the aforementioned formula, rather than only the coefficient of thermal expansion between the hydrogen embrittlement resistant layer and the stress-relief layer adjacent to its upper surface.

[0051] In some specific embodiments, the thickness of the single-layer stress relief layer is ≤1 micrometer, more preferably ≤0.05 micrometers. During the operation of the accelerator neutron source, the target temperature rises due to the deposition of proton energy, thus requiring target cooling. If the added stress relief layer is too thick, it will increase the difficulty of target cooling, and if the ideal cooling effect cannot be achieved, it will lead to target overheating or even melting. Therefore, the present invention limits the thickness of the single-layer stress relief layer to the above-mentioned range.

[0052] In some specific embodiments, the thickness of a single layer of the hydrogen embrittlement resistant layer is 0.2-2 micrometers, more preferably 0.8-1.2 micrometers. For most hydrogen embrittlement resistant layer materials, the overall optimal thickness is 20-30 micrometers. Considering that film stress accumulates with increasing film thickness, the thickness of each layer must ensure that stress does not cause the film to crack. Therefore, the present invention limits the thickness of a single layer of the hydrogen embrittlement resistant layer to the above range.

[0053] In some specific embodiments, the number of stress-relief layers and hydrogen embrittlement-resistant layers is both n, where n = the theoretically required total thickness of the hydrogen embrittlement-resistant layer / the thickness of a single hydrogen embrittlement-resistant layer. The theoretically required total thickness of the hydrogen embrittlement-resistant layer is determined by the proton energy passing through the active layer (e.g., 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 based on the requirements of the neutron source target. The determined thickness varies depending on the parameters and requirements of different neutron sources and can be determined according to actual needs.

[0054] 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.

[0055] In this invention, the aforementioned elements are selected as materials for the stress-relieving layer. Besides the requirement that their coefficient of thermal expansion conforms to the aforementioned formula, thermal conductivity is also an indicator for evaluating the material's suitability as a stress-relieving layer, in order to further ensure timely cooling of the target. The aforementioned materials, while meeting the requirements for coefficient of thermal expansion, also possess good thermal conductivity, thus making them preferred materials.

[0056] 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.

[0057] Further preferably, the stress relief layer is made of chromium and the hydrogen embrittlement resistant layer is made of tantalum; or the stress relief layer is made of titanium and the hydrogen embrittlement resistant layer is made of tantalum; or the stress relief layer is made of zirconium and the hydrogen embrittlement resistant layer is made of tantalum; or the stress relief layer is made of chromium and the hydrogen embrittlement resistant layer is made of niobium; or the stress relief layer is made of titanium and the hydrogen embrittlement resistant layer is made of niobium.

[0058] In some specific embodiments, the target layer is a lithium target layer or a beryllium target layer.

[0059] Specific embodiments and comparative examples Comparative Example 1 (1) A special polishing solution for copper was used as the chemical treatment solution and the copper was completely immersed in it for 5 minutes. The main components of the polishing solution were 25% nitric acid, 50% sulfuric acid, 0.5% hydrochloric acid, 3% brightener, and the remainder was water. Finally, the copper substrate was cleaned with acetone, alcohol and ultrapure water for 5 minutes in sequence and then placed in a vacuum drying oven to dry for 1 hour.

[0060] (4) The treated copper substrate is attached to a stainless steel plate and mounted on the fixture of the magnetron sputtering equipment, placed parallel to the tantalum target, with a fixed distance of 10cm; the magnetron sputtering process parameters are adjusted for sputtering, the sputtering parameters are: target power 300W, sputtering time 60min, gas pressure 0.5Pa, vacuum degree 5×10 -4 Pa, with a duty cycle of 90%.

[0061] Comparative Example 2 (1) Polish with 80 grit sandpaper for 5 minutes, then polish with 200 and 400 grit sandpaper for 5 minutes each. Finally, clean the copper substrate with acetone, alcohol and ultrapure water for 5 minutes each, and then dry it in a vacuum drying oven for 1 hour.

[0062] (2) The treated copper substrate is attached to a stainless steel plate and mounted on the fixture of the magnetron sputtering equipment, placed parallel to the tantalum target, with a fixed distance of 10 cm; the magnetron sputtering process parameters are adjusted for sputtering, with the sputtering parameters being: target power 300W, sputtering time 60 min, gas pressure 0.5 Pa, and vacuum degree 5×10 -4 Pa, with a duty cycle of 90%.

[0063] Comparative Example 3 (1) The substrate surface was treated with 150-mesh quartz sand using a pressure-type sandblasting machine for 2 minutes. Finally, the copper substrate was cleaned with acetone, alcohol and ultrapure water for 5 minutes in sequence and then placed in a vacuum drying oven to dry for 1 hour.

[0064] (2) The processed copper substrate is attached to a stainless steel plate and installed on the fixture of the magnetron sputtering equipment, and placed parallel to the tantalum target, with a fixed distance of 10cm; the magnetron sputtering process parameters are adjusted for sputtering, the sputtering parameters are target power 300W, sputtering time 60min, gas pressure 0.5Pa, vacuum degree 5×10-4Pa, and duty cycle 90%.

[0065] Comparative Example 4: The copper sheet was surface-treated by setting the laser parameters to 10 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and cross-scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0066] Example 1: The copper sheet was surface-treated after the laser parameters were set to 10 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0067] Example 2: The copper sheet was surface-treated after the laser parameters were set to 12.5 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0068] Example 3: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0069] Example 4: The copper sheet was surface-treated after the laser parameters were set to 17.5 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0070] Example 5: The copper sheet was surface-treated after the laser parameters were set to 20 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0071] Comparative Example 5: The copper sheet was surface-treated by setting the laser parameters to 22.5 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0072] Comparative Example 6: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 2.5 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0073] Example 6: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 5 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0074] Example 7: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 10 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0075] Example 8: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 20 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0076] Example 9: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 25 μm laser line spacing, 50 ns pulse duration, 500 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0077] Example 10: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 10 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0078] Example 11: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 50 mm / s scanning speed, and parallel laser scanning mode. This was followed by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0079] Example 12: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 100 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0080] Example 13: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 200 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0081] Example 14: The copper sheet was surface-treated after the laser parameters were set to 15 W laser power, 15 μm laser line spacing, 50 ns pulse duration, 1000 mm / s scanning speed, and parallel laser scanning mode. Magnetron sputtering was then performed (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5 × 10⁻⁶). -4 Tantalum was deposited onto the surface of the laser-treated copper substrate (tantalum film thickness was 1 μm) using a sputtering time of 1 hour (Pa).

[0082] Performance testing The surface finish of the copper substrates after surface treatment and the coating effect of each embodiment and comparative example are shown in the following table and Figure 1-10 As shown: Blank group / / / / / Smooth surface Large-area film peeling and bubbling Comparative Example 1 Chemical solvent etching / / / / The surface is relatively smooth and free of micropores. Large-area film detachment Comparative Example 2 Mechanical grinding / / / / The surface has obvious parallel scratches and no micropores. Large-area film peeling and bubbling Comparative Example 3 Sandblasting / / / / The surface is rough with obvious pits and no micropores. Large-area film peeling and bubbling Comparative Example 4 laser cross 10 15 500 No parallel grooves Large-area film detachment Example 1 laser parallel 10 15 500 There are obvious parallel grooves, but the surface of the grooves is almost free of micropores. / Example 2 laser parallel 12.5 15 500 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 3 laser parallel 15 15 500 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 4 laser parallel 17.5 15 500 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 5 laser parallel 20 15 500 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Comparative Example 5 laser parallel 22.5 15 500 There are obvious parallel grooves, but the interconnected micropores on the groove surface cause an excessive height difference. / Comparative Example 6 laser parallel 15 2.5 500 No obvious parallel grooves / Example 6 laser parallel 15 5 500 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 7 laser parallel 15 10 500 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 8 laser parallel 15 20 500 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 9 laser parallel 15 25 500 The trench has no width but a large depth. / Example 10 laser parallel 15 15 10 There is an abnormal protrusion / Example 11 laser parallel 15 15 50 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 12 laser parallel 15 15 100 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 13 laser parallel 15 15 200 There are obvious parallel grooves and micropores on the surface of the grooves. The film is uniform and flat. Example 14 laser parallel 15 15 1000 There are obvious parallel grooves, but the surface of the grooves is almost free of micropores. / Based on the data in the table above and Figure 1-10 It can be known that: (1) Surface treatment effect: Comparative Examples 1-3 were processed using chemical solvent etching, mechanical polishing, and sandblasting, respectively. The results showed that none of these methods could achieve the target morphological features of this invention. For example... Figure 2 As shown, the substrate surface after chemical solvent etching in Comparative Example 1 is relatively smooth and free of micropores; Figure 3 As shown, the substrate surface of Comparative Example 2, after mechanical polishing, has obvious parallel scratches and no micropores; as Figure 4 As shown, the substrate surface of Comparative Example 3 after sandblasting is rough, but without micropores. Comparative Example 4 uses a cross-scan laser treatment, and the results show that no parallel grooves are formed on the substrate surface.

[0083] Examples 1-5 and Comparative Example 5 were laser-treated on the substrate surface using different laser powers. The results showed that in Example 1, due to the relatively low laser power, obvious parallel grooves were formed, but the groove surface had almost no micropores. In Examples 2-5, as the laser power gradually increased, obvious parallel grooves were formed, and the groove surface had micropores. In particular, the surface treatment effect of Example 3 was closest to the target morphology (e.g., ...). Figure 1 (As shown). In contrast, Comparative Example 5, due to its higher laser power, also showed obvious parallel grooves, but the interconnected micropores on the groove surface resulted in excessive height differences, which was detrimental to subsequent coating.

[0084] Comparative Example 6, Examples 6-7, Example 3, and Examples 8-9 were laser-treated on the substrate surface using different laser spacings. The results showed that: Comparative Example 6 had no obvious parallel grooves due to its small spacing; Examples 6-7, 3, and 8 had moderate laser spacings, which could form obvious parallel grooves with micropores on the groove surface; while Example 9 had a large spacing, resulting in grooves with no width and a large depth.

[0085] Examples 10-13, 3, and 14 were laser-processed on the substrate surface using different scanning speeds. The results showed that: Example 10 had a slow scanning speed, resulting in abnormal protrusions; Examples 11-13 and 3 had relatively ideal scanning speeds, which could form obvious parallel grooves with micropores on the groove surface; while Example 14 had a high scanning speed, resulting in obvious parallel grooves but almost no micropores on the groove surface.

[0086] (2) Coating effect: Figure 5 The images show the coated surfaces of Examples 2-5 (first row from left to right, 2 samples per case), Examples 6-7 / Example 3 / Example 8 (second row from left to right, 2 samples per case), Examples 11-13 / Example 3 (third row from left to right, 2 samples per case), Comparative Example 1 (fourth row), Comparative Example 2 (all samples in the fifth row), and Comparative Example 3 (all samples in the sixth row). It can be seen that the coating on the surface of the samples in the first three rows is relatively flat and smooth, while the coating in the latter three rows shows large-area peeling and blistering, indicating a poor coating effect.

[0087] Figure 6-8 The images show scanning electron microscope (SEM) images, copper elemental distribution maps, and tantalum elemental distribution maps of a 1 μm tantalum film deposited by magnetron sputtering on an untreated copper substrate (blank group). Figure 6 Visible signs include thin film peeling and flaking on the surface. Figure 7 and Figure 8As can be seen, the copper substrate was exposed in the area where the coating peeled off, and the elemental distribution map showed an accumulation of copper, while the area where the coating did not peel off showed an accumulation of tantalum. These results indicate that tantalum coatings will peel off on copper substrates that have not undergone laser surface treatment.

[0088] Figure 9 and Figure 10 The figures show the copper and tantalum element distribution maps after coating in Example 3, respectively. It can be seen that after laser surface treatment in Example 3, almost no copper element was detected in the element distribution map, while tantalum element accumulated throughout the surface, indicating that the tantalum layer covered the substrate surface. These results demonstrate that, compared to the untreated surface, the tantalum layer plated on the copper substrate treated by laser in Example 3 does not exhibit peeling or flaking, and has good coverage.

[0089] An embodiment where the intermediate layer is a composite intermediate layer Example 15 (Single-layer stress relief layer and single-layer hydrogen embrittlement resistant layer) S1: After setting the laser parameters to laser power of 15W, laser line spacing of 15μm, pulse duration of 50ns, scanning speed of 500mm / s and parallel laser scanning mode, perform surface treatment on the copper sheet.

[0090] S2: Using the processed copper sheet as a substrate, mount it on the workpiece holder of the magnetron sputtering coating machine, place it inside the chamber of the magnetron sputtering coating machine, and evacuate to 8×10⁻⁶. -4 Below Pa; introduce 20 SCCM of argon gas into the chamber, control the sputtering pressure to 0.5 Pa, and move the workpiece holder to the position of the chromium target; set the tantalum target power to 300 W and sputter chromium on the copper substrate for 10 minutes; after the chromium sputtering process is completed, turn off the chromium target power, move the workpiece holder to the position of the tantalum target; set the tantalum target power to 300 W and sputter tantalum on the substrate for 1 hour; after the sputtering process is completed, balance the gas pressure inside and outside the chamber, and take out the substrate with the stress relief layer of chromium and the hydrogen embrittlement resistance layer deposited in sequence.

[0091] The composite intermediate layer deposited 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 stress relief layer is 40 nm; the thickness of the single hydrogen embrittlement resistant layer is 1 μm; the stress relief layer (Cr, 8.6 × 10⁻⁶) -6 / K) and its upper surface adjacent hydrogen embrittlement resistant layer (Ta, 6.3 × 10) -6 The coefficient of thermal expansion (k) satisfies the following relationship:

[0092] The resulting intermediate layer has a very smooth and uniform surface.

[0093] Example 16 (5-layer stress relief layer and 5-layer hydrogen embrittlement resistant layer) The difference between this embodiment and Embodiment 15 is that the treated copper sheet is used as the substrate, and chromium and tantalum are repeatedly sputtered onto the substrate surface for a total of 5 cycles. The composite intermediate layer deposited 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 approximately 200 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 μm, and the total thickness is approximately 5 μm. The resulting intermediate layer surface exhibits a very smooth and uniform appearance.

[0094] Example 17 (20-layer stress relief layer and 20-layer hydrogen embrittlement resistant layer) The difference between this embodiment and Embodiment 15 is that the treated copper sheet is used as the substrate, and chromium and tantalum are repeatedly sputtered onto the substrate surface for a total of 20 cycles. The composite intermediate layer deposited on the substrate surface 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, with a total thickness of approximately 800 nm; the thickness of a single hydrogen embrittlement-resistant layer is 1 micrometer, with a total thickness of approximately 20 μm. The resulting intermediate layer surface exhibits a very smooth and uniform appearance.

[0095] Example 18 (The difference from Example 15 is that the stress relief layer material is titanium) The difference between this embodiment and Embodiment 15 is that: the treated copper sheet is used as the substrate, and titanium and tantalum are repeatedly sputtered onto the substrate surface for a total of 5 cycles. The composite intermediate layer deposited on the substrate surface 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, with a total thickness of approximately 190 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 μm, with a total thickness of approximately 5 μm; the stress relief layer (Ti, 8.6 × 10⁻⁶) -6 / K) and its upper surface adjacent hydrogen embrittlement resistant layer (Ta, 6.3 × 10) -6 The coefficient of thermal expansion (K) satisfies the following relationship:

[0096] The resulting intermediate layer has a very smooth and uniform surface.

[0097] Example 19 (The difference from Example 15 is that the stress relief layer material is zirconium) The difference between this embodiment and Embodiment 15 is that: the treated copper sheet is used as the substrate, and zirconium and tantalum are repeatedly sputtered onto the substrate surface for a total of 5 cycles. The composite intermediate layer deposited on the substrate surface 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, with a total thickness of approximately 140 nm; the thickness of a single hydrogen embrittlement resistant layer is 1 μm, with a total thickness of approximately 5 μm; the stress relief layer (Zr, 5.5 × 10⁻⁶) -6 / K) and its upper surface adjacent hydrogen embrittlement resistant layer (Ta, 6.3 × 10) -6 The coefficient of thermal expansion (K) satisfies the following relationship:

[0098] The resulting intermediate layer has a very smooth and uniform surface.

[0099] Example 20 (The difference from Example 15 is that the stress relief layer material is titanium and the hydrogen embrittlement resistant layer material is niobium) The difference between this embodiment and Embodiment 15 is that: the treated copper sheet is used as the substrate, and titanium and niobium are repeatedly sputtered onto the substrate surface for a total of 5 cycles. The composite intermediate layer deposited on the substrate surface 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, with a total thickness of approximately 190 nm; the thickness of a single hydrogen embrittlement resistant layer is 0.8 μm, with a total thickness of approximately 4 μm; the stress relief layer (Ti, 8.6 × 10⁻⁶) -6 / K) and its upper surface adjacent hydrogen embrittlement resistant layer (Nb, 7.2 × 10) -6 The coefficient of thermal expansion (K) satisfies the following relationship:

[0100] The resulting intermediate layer has a very smooth and uniform surface.

[0101] Example 21 (The difference from Example 15 is that the hydrogen embrittlement resistant layer material is niobium) The difference between this embodiment and Embodiment 15 is that: the treated copper sheet is used as the substrate, and chromium and niobium are repeatedly sputtered onto the substrate surface for a total of 5 cycles. The composite intermediate layer deposited on the substrate surface 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, with a total thickness of approximately 200 nm; the thickness of a single hydrogen embrittlement resistant layer is 0.8 μm, with a total thickness of approximately 4 μm; the stress relief layer (Cr, 8.6 × 10⁻⁶) -6 / K) and its upper surface adjacent hydrogen embrittlement resistant layer (Nb, 7.2 × 10) -6 The coefficient of thermal expansion (K) satisfies the following relationship:

[0102] The resulting intermediate layer has a very smooth and uniform surface.

[0103] Example 22 An accelerator neutron source target includes: a substrate (same as in Example 3); a composite intermediate layer disposed on the upper surface of the substrate (Example 15); a target material layer (lithium) disposed on the upper surface of the composite intermediate layer; and a protective layer (titanium) covering the outer surfaces of the target material layer and the composite intermediate layer.

[0104] Example 23 An accelerator neutron source target includes: a substrate (same as in Example 3); a composite intermediate layer disposed on the upper surface of the substrate (Example 15); a target material layer (beryllium) disposed on the upper surface of the composite intermediate layer; and a protective layer (titanium) covering the outer surfaces of the target material layer and the composite intermediate layer.

[0105] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A neutron source target, comprising a substrate, an intermediate layer disposed on the surface of the substrate, and a target material layer disposed on the surface of the intermediate layer, characterized in that: The surface where the substrate and the intermediate layer are bonded is provided with corrugated parallel trenches; the surface of the parallel trenches is distributed with micropores. The intermediate layer is a composite intermediate layer; the composite intermediate layer includes at least one stress relief layer and at least one hydrogen embrittlement resistant layer stacked in an alternating manner; The stress relief layer, which is located at the bottom layer, is disposed on the upper surface of the substrate, and the hydrogen embrittlement resistant layer, which is located at the top layer, is disposed on the lower surface of the target material layer. The deviation of the coefficient of thermal expansion of each of the aforementioned anti-hydrogen embrittlement layers relative to the stress relief layer adjacent to its lower surface is ≤30%; The thickness of a single stress-relief layer is ≤1 micrometer; the thickness of a single hydrogen embrittlement-resistant layer is 0.5-2 micrometers.

2. The neutron source target according to claim 1, characterized in that: The width of the parallel trenches is 30-60 micrometers; the size of the micropores is 5-30 micrometers.

3. The neutron source target according to claim 1 or 2, characterized in that: The method for constructing the surface structure where the substrate and the intermediate layer are bonded includes: A laser is used to perform laser surface treatment on the neutron source target substrate; wherein: a parallel laser scanning method is used, the laser power is 12.5-20W, the pulse duration is 50ns, the laser line spacing is 5-20μm, and the scanning speed is 50-500mm / s.

4. The neutron source target according to claim 3, characterized in that: Laser surface treatment employs a parallel laser scanning method with a laser power of 15-20W, a pulse duration of 50ns, a laser line spacing of 5-15μm, and a scanning speed of 100-500mm / s.

5. The neutron source target according to claim 3, characterized in that: The neutron source target substrate is made of copper, vanadium, tungsten, gold, platinum, lead, or alloys thereof.

6. The neutron source target according to claim 3, characterized in that: The neutron source target substrate has undergone surface pre-cleaning.

7. The neutron source target according to claim 1 or 2, characterized in that: The intermediate layer is formed by spraying, physical vapor deposition, chemical vapor deposition or electroplating.

8. The neutron source target according to claim 1, characterized in that: 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.

9. The neutron source target according to claim 1, characterized in that: The material of the anti-hydrogen embrittlement layer is selected from one or more of tantalum, vanadium, palladium, niobium, platinum, tungsten and their oxides.

10. The neutron source target according to claim 1 or 2, characterized in that: The target layer is a lithium target layer or a beryllium target layer.

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