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

Abstract

The invention relates to the field of medical instruments, 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 corrugated parallel grooves; holes are distributed in the surfaces of the parallel grooves. The construction method comprises the following steps: carrying out laser surface treatment on a neutron source target substrate by adopting a laser; wherein a parallel laser scanning mode is adopted, the laser power ranges from 0 W to 20 W, the pulse duration ranges from 0 ns to 100 ns, the laser line spacing ranges from 5 microns to 30 microns, and the scanning speed ranges from 10 mm / s to 1000 mm / s; and processing to obtain the neutron source target substrate with surface topography characteristics. The laser surface treatment is carried out on the neutron source target substrate, and the microstructure, roughness and coating crystallinity of the surface of the neutron source target substrate can be regulated and controlled, so that favorable conditions are provided for further constructing a target material intermediate layer with a high coating effect on the surface of the neutron source target substrate.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and particularly to a surface structure of a neutron source target substrate and a method for constructing the same by laser surface treatment. Background Art

[0002] In the preparation process of an accelerator neutron source target, it is first necessary to introduce a layer of material on the substrate to alleviate hydrogen embrittlement caused by hydrogen accumulation and bubbling after protons are completely stopped. At present, common coating methods for anti-hydrogen embrittlement layer materials include thermal spraying, physical vapor deposition (PVD), chemical vapor deposition (CVD), etc. If the above methods are directly used to deposit the anti-hydrogen bubbling layer material on the substrate, due to the oxide layer, impurities, and surface smoothness of the substrate surface, the bonding force between the coating layer and the substrate is weak, and peeling or falling off is likely to occur. Therefore, the substrate needs to be surface-treated before coating to improve the coating effect of the anti-hydrogen embrittlement layer of the neutron source target.

[0003] Currently, common material surface treatment methods include mechanical grinding treatment, chemical etching treatment, laser treatment, etc. These different surface treatment methods have their own advantages and disadvantages. For example, the advantage of mechanical grinding is low equipment requirements, but the disadvantages are long processing time and inability to ensure surface uniformity. The advantage of chemical etching treatment is simple operation, but the disadvantages are easy to cause excessive corrosion or damage to the substrate, and the need to use toxic or corrosive chemical substances, which poses certain risks to the environment and operators. The advantage of laser surface treatment is high precision and high working efficiency, but the disadvantage is that when the temperature of the workpiece surface suddenly rises and falls, there is a large internal stress in the substrate, which may lead to the formation and expansion of cracks in the subsequent thin film.

[0004] In the prior art, people often only focus on the surface roughness or specific surface area of the substrate surface after surface treatment, and rarely pay attention to the influence of the substrate surface morphology characteristics on the subsequent coating. The research team of the present invention found that for a substrate used as a neutron source target, compared with other substrates to be coated, in addition to meeting a certain surface roughness to increase the specific surface area, there are also special requirements for the surface morphology of the substrate: The research team of the present invention found in previous experiments that if a parallel groove microstructure arranged in a wavy shape is constructed on the substrate surface, compared with an ordinary rough surface, this special microstructure can not only significantly increase the surface roughness (increase the specific surface area), but more importantly, in the subsequent coating process, the above parallel groove microstructure can effectively fix the high-energy particles of magnetron sputtering, induce nucleation, thereby adjusting the coating crystallinity and better improving the interfacial bonding force between the coating and the substrate. When the neutron source target is in long-term service, this structure is more conducive to heat diffusion and micro-region stress relief to extend the target material life.

[0005] Therefore, in order to improve the surface coating effect of the substrate of the neutron source target, it is necessary to construct the above-mentioned specific microscopic morphology structure on the surface of the neutron source target substrate. However, how to stably and efficiently construct the above-mentioned special surface morphology characteristics on the substrate surface through the existing surface treatment methods has not been deeply studied in the prior art. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a surface structure of a neutron source target substrate and a method for constructing it by laser surface treatment. By performing laser surface treatment on the neutron source target substrate, the present invention can regulate the microscopic morphology, roughness, and crystallinity of the coating on the surface of the neutron source target substrate, thereby providing favorable conditions for further constructing an intermediate layer of the target material with a high coating effect on its surface.

[0007] The specific technical solution of the present invention is as follows: In the first aspect, the present invention provides a surface structure of a neutron source target substrate. The surface of the substrate that combines with the intermediate layer is provided with parallel grooves in a wavy shape; micropores are distributed on the surface of the parallel grooves.

[0008] Preferably, the width of the parallel grooves is 30 - 60 microns; the size of the micropores is 5 - 30 microns.

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

[0010] The research team of the present invention found that in order to construct a high-quality intermediate layer of the target material subsequently, 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 present invention further found that: constructing a parallel groove microstructure arranged in a wavy shape on the substrate surface, compared with an ordinary rough surface, this special microstructure can not only significantly increase the surface roughness (increase the specific surface area), but more importantly, in the subsequent coating process, the above-mentioned parallel groove microstructure can effectively fix the high-energy particles of magnetron sputtering, induce nucleation, and thus regulate the crystallinity of the coating; at the same time, after the high-energy particles reach the surface of the parallel groove microstructure, the micropores on its surface can be better filled, thereby better improving the interfacial bonding force between the coating and the substrate. When the neutron source target serves for a long time, this structure is more conducive to heat diffusion and stress relief in the micro-region, so as to extend the service life of the target material.

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

[0012] Since the surface after laser treatment is a special surface between isotropic and anisotropic, its morphological characteristics are very different from those of the surfaces of traditional machining and electrical discharge machining. During the laser treatment process, while the laser beam moves on the substrate surface, high temperature is generated, which vaporizes and melts the material. The generated molten material accumulates together in the laser scanning direction, forming a series of wavy parallel grooves with a width of 30-60 microns along the laser scanning trajectory. Therefore, this structure is highly similar to the target microstructure.

[0013] In addition, we also found that the process of high-temperature melting followed by low-temperature solidification will generate some micropores with irregular sizes of about 5-30 microns on the surface of each groove. During the subsequent magnetron sputtering process, after high-energy particles reach the surface of the parallel grooves, the micropores on its surface can be better filled, thus better improving the interfacial bonding force between the coating and the substrate; when the neutron source target serves for a long time, this microporous structure can also further facilitate heat diffusion and stress relief in the micro-region.

[0014] In summary, the present invention regulates the microscopic morphology, roughness and coating crystallinity of the surface of the neutron source target substrate through laser treatment, thereby providing favorable conditions for further constructing an intermediate layer of the target material with a high coating effect on its surface.

[0015] Preferably, a parallel laser scanning method is adopted, with a laser power of 0-20 W, a pulse duration of 0-100 ns, a laser line spacing of 5-30 μm, and a scanning speed of 10-1000 mm / 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] The present invention further discovers through experiments that different laser treatment conditions have a certain impact on the surface morphology of the neutron source target substrate (including the microstructure size and the ability to generate micropores, etc.). Therefore, in order to obtain a substrate surface closer to the target morphological characteristics, the present invention preferably and more preferably adopts the above laser treatment process.

[0018] If the laser treatment degree is insufficient, it will lead to the inability to form a sufficient number of microporous structures on the groove surface. On the contrary, if the laser treatment degree is too high, it will lead to the continuous arrangement of surface micropores along the laser movement direction, forming a surface with a large height difference. Such a surface has a serious shadow effect during the sputtering process, which is not conducive to the later film growth.

[0019] Preferably, the material of the neutron source target substrate is copper, vanadium, tungsten, gold, platinum, lead or their alloys.

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

[0021] In a third aspect, the present invention provides a neutron source target, including a substrate, an intermediate layer provided on the surface of the substrate, and a target material layer provided on the surface of the intermediate layer. The surface of the substrate where it combines with the intermediate layer is provided with corrugated parallel grooves; micropores are distributed on the surface of the parallel grooves.

[0022] Preferably, the width of the parallel grooves is 30 - 60 microns; the size of the micropores is 5 - 30 microns.

[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 alternately laminated; The stress relief layer located at the bottommost layer is provided on the upper surface of the substrate, and the hydrogen embrittlement resistant layer located at the topmost layer is provided on the lower surface of the target material layer.

[0026] Preferably, the deviation of the thermal expansion coefficient of each hydrogen embrittlement resistant layer relative to the stress relief layer adjacent to its lower surface is ≤ 30%, which can be expressed as: In the formula: α is the thermal expansion coefficient of the corresponding layer, with the unit 1 / °C.

[0027] Preferably, the thickness of a single stress relief layer is ≤ 1 micron, and more preferably ≤ 0.05 micron.

[0028] Preferably, the thickness of a single hydrogen embrittlement resistant layer is 0.2 - 2 microns, and more preferably 0.8 - 1.2 microns.

[0029] 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 hydrogen embrittlement resistant layer.

[0030] 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.

[0031] 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 material layer is a lithium target layer or a beryllium target layer.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By performing laser surface treatment on the neutron source target substrate, the present invention can regulate the microscopic morphology, roughness, and coating crystallinity of the surface of the neutron source target substrate, thereby providing favorable conditions for further constructing a target intermediate layer with a high coating effect on its surface.

[0033] (2) The present invention uses a laser treatment method to perform surface pretreatment on the neutron source target substrate. This method does not use toxic chemical substances, which can not only reduce environmental pollution and operation risks, but also reduce costs and operation difficulties.

[0034] (3) By further constructing a target composite intermediate layer on the surface of the neutron source target substrate, the present invention can improve the adhesion, crystallinity, composition uniformity, and thermal stability of the original intermediate layer, thereby enhancing its bonding force with the substrate and solving the problem of easy detachment during the preparation of the existing intermediate layer, so as to prepare an accelerator neutron source target system with high performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the scanning electron microscope image of the substrate surface after treatment in Example 3; Figure 2 is the scanning electron microscope image of the substrate surface after treatment in Comparative Example 1; Figure 3 is the scanning electron microscope image of the substrate surface after treatment in Comparative Example 2; Figure 4 is the scanning electron microscope image of the substrate surface after treatment in Comparative Example 3; Figure 5 is the photograph of the substrate after coating in each case; Figure 6 is the scanning electron microscope image of the blank group substrate after coating; Figure 7 is the copper element distribution map of the blank group substrate after coating; Figure 8 is the tantalum element distribution map of the blank group substrate after coating; Figure 9 is the copper element distribution map of the substrate after coating in Example 3; Figure 10 is the tantalum element distribution map of the substrate after coating in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention will be further described below in conjunction with the embodiments.

[0037] General Embodiment A method for constructing the surface structure of a neutron source target substrate based on laser surface treatment, comprising: performing laser surface treatment on the neutron source target substrate using a laser; wherein: a parallel laser scanning method is adopted, the laser power is 0 - 20 W, the pulse duration is 0 - 100 ns, the laser line spacing is 5 - 30 μm, and the scanning speed is 10 - 1000 mm / s; after treatment, a neutron source target substrate with parallel groove microstructures arranged in a corrugated shape (preferably with a width of about 30 - 60 microns) and irregular micropores (preferably about 5 - 30 microns) on the groove surface is obtained.

[0038] In some more preferred embodiments, the laser surface treatment adopts a parallel laser scanning method, the laser power is 10 - 20 W, the pulse duration is 0 - 80 ns, the laser line spacing is 5 - 20 μm, and the scanning speed is 50 - 500 mm / s.

[0039] In some specific embodiments, the material of the neutron source target substrate is copper, vanadium, tungsten, gold, platinum, lead or an alloy thereof.

[0040] In some specific embodiments, the neutron source target substrate is pre-cleaned on the surface to remove surface impurities and oil; more preferably, an organic solvent and deionized water are used for cleaning.

[0041] In some specific embodiments, the intermediate layer is formed by spraying, physical vapor deposition, chemical vapor deposition or electroplating.

[0042] A neutron source target, comprising a substrate, an intermediate layer provided on the surface of the substrate, and a target material layer provided on the surface of the intermediate layer, wherein the surface of the substrate combined with the intermediate layer is provided with parallel grooves in a corrugated shape (preferably with a width of about 30 - 60 microns); micropores are distributed on the surface of the parallel grooves (the size is preferably about 5 - 30 microns).

[0043] In some specific embodiments, the intermediate layer is a hydrogen embrittlement resistant layer or a composite intermediate layer.

[0044] 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 alternately laminated; the stress relief layer located at the bottommost layer is provided on the upper surface of the substrate, and the hydrogen embrittlement resistant layer located at the topmost layer is provided on the lower surface of the target material layer.

[0045] Different from another solution of the present invention (the intermediate layer is a relatively thick single hydrogen embrittlement resistant layer), in this solution of the present invention, the intermediate layer 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. After introducing the stress relief layer, an interface layer will be formed, which can be used to improve the adhesion, crystallinity, composition uniformity, thermal stability and other properties of the intermediate layer, thereby improving the bonding strength between the intermediate layer and the substrate, solving the problem of easy peeling off during the preparation of the existing intermediate layer, and preparing an accelerator neutron source target system with high performance and stability.

[0046] The principle of the present invention to design the intermediate layer as at least one stress relief layer and at least one hydrogen embrittlement resistant layer stacked in an interleaved manner is as follows: First, the original relatively thick single hydrogen embrittlement resistant layer is disassembled into multiple hydrogen embrittlement resistant layers with relatively thin thicknesses. During the processing using methods such as vapor deposition, it can relieve the technical problems such as thermal stress generated during the deposition process, poor interface, or insufficient bonding strength caused by other factors leading to the peeling of the intermediate layer. 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 relatively thick intermediate layer, thereby avoiding deformation, cracking or failure of the intermediate layer. 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 interleaved stacking method can relieve 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.

[0047] In some specific embodiments, the thermal expansion coefficients of each stress relief layer and the hydrogen embrittlement resistant layer adjacent to its upper surface satisfy the following relationship: In the formula: α is the thermal expansion coefficient of the corresponding layer, with the unit of 1 / °C.

[0048] The present invention finds that the thermal expansion coefficient is the main factor leading to stress accumulation during the thin film deposition process. Therefore, by controlling the expansion coefficients of adjacent two layers of materials within the above specific range, if the expansion coefficient difference is greater than the above range, it will lead to uneven stress distribution and cause the thin film to rupture. And since the deposited hydrogen embrittlement resistant layer materials are all grown on the upper surface of the stress relief layer, a good bonding strength 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 stress relief layer adjacent to its lower surface satisfies the above formula, rather than the stress relief layer adjacent to its upper surface.

[0049] In some specific embodiments, the thickness of a single layer of the stress relief layer is ≤ 1 μm, and more preferably ≤ 0.05 μm. 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 to heat up 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.

[0050] In some specific embodiments, 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. For most hydrogen embrittlement resistant layer materials, the overall optimal thickness is 20 - 30 μm. Considering that the 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 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.

[0051] In some specific embodiments, the number of layers of both the stress relief layer and the hydrogen embrittlement resistant layer is n, where n = the total theoretical thickness required for the hydrogen embrittlement resistant layer / the thickness of a single layer of the hydrogen embrittlement resistant layer. The total theoretical thickness required for the hydrogen embrittlement resistant layer is determined by the proton energy passing through the action 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. According to the parameters and requirements of different neutron sources, the determined thickness is different and can be determined according to actual needs.

[0052] 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.

[0053] The present invention selects the above elements as the material of the stress relief layer. In addition to its thermal expansion coefficient needing to meet the aforementioned formula, at the same time, in order to further ensure the timely cooling of the target, the thermal conductivity is also one of the indicators 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.

[0054] 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.

[0055] 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.

[0056] In some specific embodiments, the target layer is a lithium target layer or a beryllium target layer.

[0057] Specific examples and comparative examples Comparative Example 1 (1) Using a special polishing solution for copper as the chemical treatment solution and completely immersing the copper in it, the reaction time is 5 min. The main components of the polishing solution are 25% nitric acid, 50% sulfuric acid, 0.5% hydrochloric acid, 3% brightening agent, and the balance is water. Finally, the copper substrate is cleaned with acetone, alcohol, and ultrapure water in sequence for 5 min each and then placed in a vacuum drying oven to dry for 1 h.

[0058] (4) The treated copper substrate is attached to a stainless steel plate and installed on the fixture of a magnetron sputtering device, and is placed parallel to the tantalum target with a fixed distance of 10 cm; adjusting the magnetron sputtering process parameters for sputtering, the sputtering parameters are target power 300 W, sputtering time 60 min, gas pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, and the duty cycle is 90%.

[0059] Comparative Example 2 (1) Sand the copper substrate with 80-mesh sandpaper for 5 min, and then continue to polish it with 200-mesh and 400-mesh sandpapers for 5 min each. Finally, the copper substrate is cleaned with acetone, alcohol, and ultrapure water in sequence for 5 min each and then placed in a vacuum drying oven to dry for 1 h.

[0060] (2) The treated copper substrate is attached to a stainless steel plate and installed on the fixture of a magnetron sputtering device, and is placed parallel to the tantalum target with a fixed distance of 10 cm; adjusting the magnetron sputtering process parameters for sputtering, the sputtering parameters are target power 300 W, sputtering time 60 min, gas pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, and the duty cycle is 90%.

[0061] Comparative Example 3 (1) Treat the surface of the substrate with 150-mesh quartz sand using a pressure-fed sandblaster for 2 min. Finally, the copper substrate is cleaned with acetone, alcohol, and ultrapure water in sequence for 5 min each and then placed in a vacuum drying oven to dry for 1 h.

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

[0063] Comparative Example 4: After setting the laser parameters to a laser power of 10 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of cross, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness is 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10 -4 Pa, sputtering time 1 hour).

[0064] Example 1: After setting the laser parameters to a laser power of 10 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness is 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10 -4 Pa, sputtering time 1 hour).

[0065] Example 2: After setting the laser parameters to a laser power of 12.5 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness is 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10 -4 Pa, sputtering time 1 hour).

[0066] Example 3: After setting the laser parameters to a laser power of 15 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness is 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10 -4 Pa, sputtering time 1 hour).

[0067] Example 4: After setting the laser parameters to a laser power of 17.5 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness is 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10- 4 Pa, sputtering time 1 hour).

[0068] Example 5: After setting the laser parameters to a laser power of 20 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Through magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, sputtering time 1 hour), tantalum was deposited on the surface of the laser-treated copper substrate (the thickness of the tantalum film was 1 μm).

[0069] Comparative Example 5: After setting the laser parameters to a laser power of 22.5 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Through magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, sputtering time 1 hour), tantalum was deposited on the surface of the laser-treated copper substrate (the thickness of the tantalum film was 1 μm).

[0070] Comparative Example 6: After setting the laser parameters to a laser power of 15 W, a laser line spacing of 2.5 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Through magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, sputtering time 1 hour), tantalum was deposited on the surface of the laser-treated copper substrate (the thickness of the tantalum film was 1 μm).

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

[0072] Example 7: After setting the laser parameters to a laser power of 15 W, a laser line spacing of 10 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. Through magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness: 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10

[0073] Example 8: After setting the laser parameters to laser power 15 W, laser line spacing 20 μm, pulse duration 50 ns, scanning speed 500 mm / s, and laser scanning mode as parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness: 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, sputtering time 1 hour).

[0074] Example 9: After setting the laser parameters to laser power 15 W, laser line spacing 25 μm, pulse duration 50 ns, scanning speed 500 mm / s, and laser scanning mode as parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness: 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, sputtering time 1 hour).

[0075] Example 10: After setting the laser parameters to laser power 15 W, laser line spacing 15 μm, pulse duration 50 ns, scanning speed 10 mm / s, and laser scanning mode as parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness: 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, sputtering time 1 hour).

[0076] Example 11: After setting the laser parameters to laser power 15 W, laser line spacing 15 μm, pulse duration 50 ns, scanning speed 50 mm / s, and laser scanning mode as parallel, the surface of the copper sheet was treated. Tantalum was deposited on the surface of the laser-treated copper substrate (tantalum film thickness: 1 μm) by magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum degree 5×10 -4 Pa, sputtering time 1 hour).

[0077] Example 12: After setting the laser parameters to a laser power of 15 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 100 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. By magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10 -4 Pa, sputtering time 1 hour), tantalum was deposited on the surface of the laser-treated copper substrate (the tantalum film thickness was 1 μm).

[0078] Example 13: After setting the laser parameters to a laser power of 15 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 200 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. By magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10 -4 Pa, sputtering time 1 hour), tantalum was deposited on the surface of the laser-treated copper substrate (the tantalum film thickness was 1 μm).

[0079] Example 14: After setting the laser parameters to a laser power of 15 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 1000 mm / s, and a laser scanning mode of parallel, the surface of the copper sheet was treated. By magnetron sputtering (parameters: power 300 W, duty cycle 90%, sputtering pressure 0.5 Pa, vacuum 5×10 -4 Pa, sputtering time 1 hour), tantalum was deposited on the surface of the laser-treated copper substrate (the tantalum film thickness was 1 μm).

[0080] Performance test The surface of the copper substrate and the coating effect after surface treatment of each example and comparative example are as shown in the following table and Figure 1-10 shown below: From the data in the above table and Figure 1-10 it can be seen that: (1) Surface treatment effect: In Comparative Examples 1-3, the surface of the substrate was treated by chemical solvent etching, mechanical polishing, and sandblasting respectively, and it was found that the target morphological features of the present invention could not be obtained. Among them, as Figure 2 shown, the surface of the substrate after chemical solvent etching in Comparative Example 1 was relatively flat and had no micropores; as Figure 3 shown, the surface of the substrate after mechanical polishing in Comparative Example 2 had obvious parallel scratches and no micropores; as Figure 4As shown, the surface of the substrate after sandblasting in Comparative Example 3 is rough, but there are no micropores. In Comparative Example 4, laser treatment was carried out in a cross-scanning manner, and it was found that no parallel grooves were formed on the surface of the substrate.

[0081] In Examples 1-5 and Comparative Example 5, the surface of the substrate was laser-treated with different laser powers. The results showed that: in Example 1, due to the relatively small laser power, obvious parallel grooves were formed, but there were almost no micropores on the surface of the grooves. In Examples 2-5, the laser power gradually increased, and it was found that obvious parallel grooves could be formed and there were micropores on the surface of the grooves. In particular, the surface treatment effect in Example 3 was closest to the target morphological characteristics (as Figure 1 shown). In Comparative Example 5, due to the relatively large laser power, although obvious parallel grooves were also formed, the micropores on the surface of the grooves were connected, resulting in too large a height difference, which was not conducive to subsequent film coating.

[0082] In Comparative Example 6, Examples 6-7, Example 3, and Examples 8-9, the surface of the substrate was laser-treated with different laser spacings. The results showed that: in Comparative Example 6, due to the relatively small spacing, no obvious parallel grooves were formed; in Examples 6-7, Example 3, and Example 8, the laser spacings were appropriate, and obvious parallel grooves could be formed and there were micropores formed on the surface of the grooves; while in Example 9, due to the relatively large spacing, the grooves had no width and the depth was large.

[0083] In Examples 10-13, Example 3, and Example 14, the surface of the substrate was laser-treated with different scanning speeds. The results showed that: in Example 10, the scanning speed was too slow, resulting in abnormal protrusions; in Examples 11-13 and Example 3, the scanning speeds were relatively ideal, and obvious parallel grooves could be formed and there were micropores formed on the surface of the grooves; while in Example 14, the scanning speed was too large, and there were obvious parallel grooves but almost no micropores on the surface of the grooves.

[0084] (2) Film coating effect: Figure 5 The photos after film coating for Examples 2-5 (two samples for each case, from left to right in the first row), Examples 6-7 / Example 3 / Example 8 (two samples for each case, from left to right in the second row), Examples 11-13 / Example 3 (two samples for each case, from left to right in the third row), Comparative Example 1 (the fourth row), Comparative Example 2 (all samples in the fifth row), and Comparative Example 3 (all samples in the sixth row) were taken. It can be found that the film coatings on the surfaces of the samples in the first three rows are relatively flat and smooth, while in the last three rows, large-area peeling and bubbling occur, and the film coating effect is poor.

[0085] Figures 6-8 They are respectively the scanning electron microscope image, copper element distribution map, and tantalum element distribution map of the blank copper substrate without surface treatment plated with tantalum film (1 μm) by magnetron sputtering. From Figure 6 it can be seen that film peeling and falling off occur on the surface. From Figure 7 andFigure 8 It can be seen that the copper substrate is exposed in the coating peeling area, and the aggregation of copper elements is shown in the elemental distribution map, while the aggregation of tantalum elements is shown in the area where the coating has not peeled off. The above results indicate that coating peeling will occur when a tantalum layer is deposited on a copper substrate without laser surface treatment.

[0086] Figure 9 and Figure 10 They are respectively the copper element distribution map and the tantalum element distribution map after coating in Example 3. It can be seen that after the laser surface treatment in Example 3, almost no copper element is detected in the elemental distribution map, while tantalum elements are aggregated on the entire surface, indicating that the tantalum layer covers the substrate surface. The above results show that compared with the untreated surface, no peeling or falling off phenomenon occurs when a tantalum layer is deposited on the copper substrate after the laser surface treatment in Example 3, and the coverage rate is good.

[0087] Examples with a composite intermediate layer Example 15 (single-layer stress relief layer and single-layer hydrogen embrittlement resistance layer) S1: After setting the laser parameters to a laser power of 15 W, a laser line spacing of 15 μm, a pulse duration of 50 ns, a scanning speed of 500 mm / s, and a parallel laser scanning mode, the copper sheet is surface-treated.

[0088] S2: Using the treated copper sheet as the substrate, it is installed on the workpiece holder of a magnetron sputtering coater, placed in the chamber of the magnetron sputtering coater, 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 to 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 to 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 successively deposited with a stress relief layer made of chromium and a hydrogen embrittlement resistance layer made of tantalum is taken out.

[0089] 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 resistance layer; the thickness of the single-layer stress relief layer is 40 nm; the thickness of the single-layer hydrogen embrittlement resistance layer is 1 μm; the thermal expansion coefficient of the stress relief layer (Cr, 8.6×10 -6 / K) and the adjacent hydrogen embrittlement resistance layer (Ta, 6.3×10 -6 / K) on its upper surface satisfies the following relationship: The surface of the obtained intermediate layer is very smooth and uniform.

[0090] Example 16 (5 stress relief layers and 5 hydrogen embrittlement resistant layers) The difference between this example and Example 15 is that: using the treated copper sheet as the substrate, chromium and tantalum are repeatedly sputtered on the substrate surface for a total of 5 cycles. 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 μm, and the total thickness is about 5 μm. The surface of the obtained intermediate layer appears very smooth and uniform.

[0091] Example 17 (20 stress relief layers and 20 hydrogen embrittlement resistant layers) The difference between this example and Example 15 is that: using the treated copper sheet as the substrate, chromium and tantalum are repeatedly sputtered on the substrate surface for a total of 20 cycles. 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 μm, and the total thickness is about 20 μm. The surface of the obtained intermediate layer appears very smooth and uniform.

[0092] Example 18 (the difference from Example 15 is that the material of the stress relief layer is titanium) The difference between this example and Example 15 is that: using the treated copper sheet as the substrate, titanium and tantalum are repeatedly sputtered on the substrate surface for a total of 5 cycles. 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 adjacent hydrogen embrittlement resistant layer on its upper surface (Ta, 6.3×10 -6 / K) satisfies the following relationship: The surface of the obtained intermediate layer appears very smooth and uniform.

[0093] Example 19 (the difference from Example 15 is that the material of the stress relief layer is zirconium) The difference between this example and Example 15 is that: using the treated copper sheet as the substrate, zirconium and tantalum are repeatedly sputtered on the substrate surface for a total of 5 cycles. 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 adjacent hydrogen embrittlement resistant layer on its upper surface (Ta, 6.3×10 -6The coefficient of thermal expansion of ( / K) satisfies the following relationship: The surface of the obtained intermediate layer appears very smooth and uniform.

[0094] Example 20 (differing from Example 15 in that the stress relief layer material is titanium and the hydrogen embrittlement resistant layer material is niobium) The difference between this example and Example 15 is as follows: Using the treated copper sheet as the substrate, titanium and niobium are repeatedly sputtered on the substrate surface for a total of 5 cycles. 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 approximately 190 nm; the thickness of a single hydrogen embrittlement resistant layer is 0.8 microns, and the total thickness is approximately 4 μm; 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 satisfy the following relationship: The surface of the obtained intermediate layer appears very smooth and uniform.

[0095] Example 21 (differing from Example 15 in that the hydrogen embrittlement resistant layer material is niobium) The difference between this example and Example 15 is as follows: Using the treated copper sheet as the substrate, chromium and niobium are repeatedly sputtered on the substrate surface for a total of 5 cycles. 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 approximately 200 nm; the thickness of a single hydrogen embrittlement resistant layer is 0.8 microns, and the total thickness is approximately 4 μm; the stress relief layer (Cr, 8.6×10 -6 / K) and the hydrogen embrittlement resistant layer (Nb, 7.2×10 -6 / K) adjacent to its upper surface satisfy the following relationship: The surface of the obtained intermediate layer appears very smooth and uniform.

[0096] Example 22 An accelerator neutron source target, comprising: a substrate (same as in Example 3); a composite intermediate layer (Example 15) provided on the upper surface of the substrate; a target material layer (lithium) provided 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.

[0097] Example 23 An accelerator neutron source target, comprising: a substrate (same as in Embodiment 3); a composite intermediate layer provided on the upper surface of the substrate (Embodiment 15); a target material layer (beryllium) provided 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.

[0098] In the present invention, the raw materials and equipment used, unless otherwise specified, are common raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are conventional methods in the art.

[0099] The above are only preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A neutron source target substrate surface structure, characterized in that: The surface where the substrate and the intermediate layer are combined is provided with corrugated parallel grooves; and micropores are distributed on the surface of the parallel grooves.

2. The neutron source target substrate surface structure according to claim 1, characterized in that: The width of the parallel grooves is 30-60 microns; the size of the micropores is 5-30 microns.

3. A method for constructing the surface structure of the neutron source target substrate according to claim 1 or 2 based on laser surface treatment, characterized in that include: A laser is used to perform laser surface treatment on a neutron source target substrate; wherein: a parallel laser scanning method is adopted, the laser power is 0-20W, the pulse duration is 0-100ns, the laser line spacing is 5-30μm, and the scanning speed is 10-1000mm / s.

4. The method according to claim 3, characterized in that: The laser surface treatment adopts 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 50-500 mm / s.

5. The method according to claim 3 or 4, characterized in that: The neutron source target substrate is made of copper, vanadium, tungsten, gold, platinum, lead or an alloy thereof.

6. The method according to claim 3 or 4, characterized in that: The neutron source target substrate is surface pre-cleaned.

7. 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 combined is provided with corrugated parallel grooves; and micropores are distributed on the surface of the parallel grooves.

8. The neutron source target according to claim 7, characterized in that: The width of the parallel grooves is 30-60 microns; the size of the micropores is 5-30 microns.

9. The neutron source target according to claim 7 or 8, characterized in that: The intermediate layer is formed by spraying, physical vapor deposition, chemical vapor deposition or electroplating.

10. The neutron source target according to claim 7 or 8, characterized in that: The intermediate layer is a hydrogen embrittlement resistant layer or a composite intermediate layer.

11. The neutron source target according to claim 10, characterized in that: The composite intermediate layer comprises at least one stress relief layer and at least one 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 target 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%.

12. The neutron source target according to claim 11, 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.

13. The neutron source target according to claim 11, 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; and / 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.

14. The neutron source target according to claim 7 or 8, characterized in that: The target material layer is a lithium target layer or a beryllium target layer.

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