Accelerator neutron source target ta-ti binary hydrogen absorption transition layer and preparation method thereof

Abstract

The application relates to the field of neutron source targets, and discloses an accelerator neutron source target Ta-Ti binary hydrogen absorption transition layer and a preparation method thereof. The Ta-Ti binary hydrogen absorption transition layer is deposited on the surface of a substrate through a magnetron co-sputtering technology, and the Ta-Ti binary hydrogen absorption transition layer comprises uniformly distributed tantalum and titanium; the mass ratio of the tantalum and the titanium is 80:20-90:10. The Ta-Ti binary hydrogen absorption transition layer is constructed on the surface of the substrate of the accelerator neutron source target through the magnetron co-sputtering technology, the residual internal stress of the Ta-Ti binary hydrogen absorption transition layer is low, the binding force with the substrate is high, and the Ta-Ti binary hydrogen absorption transition layer is not prone to cracking and falling off; in addition, the method is simple, the target material does not need to be replaced, and the sputtering efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of neutron source targets, and more particularly to a Ta-Ti binary hydrogen absorption transition layer for an accelerator neutron source target and its preparation method. Background Technology

[0002] Boron neutron capture therapy is a rapidly developing advanced radiotherapy technique that utilizes boron neutrons to induce neutrons within cells. 10 B(n, α) 7 Li nucleus reactions kill cancer cells, representing an atomic-level binary targeted therapy. To achieve this treatment, not only are neutron-capture drugs needed, but also a suitable neutron source; both are core elements of BNCT (Bipolar Non-Cellular Therapy). Currently, there are two suitable neutron beam sources internationally: one obtained through reactors, and the other through accelerator neutron sources. Accelerator-based neutron sources accelerate protons using high-energy accelerators, and the high-energy protons then strike a target to produce neutrons. These accelerators can be categorized into three types based on their accelerator type: radiofrequency linear accelerators, cyclotron accelerators, and high-voltage accelerators, offering advantages such as safety, reliability, and flexible use. In recent years, accelerator-based neutron sources have matured and have become the preferred neutron source in clinical practice.

[0003] The neutron source target is the component that produces neutrons. For accelerator neutron sources, the target, which undergoes nuclear reactions and produces neutrons, is one of the most critical and also one of the most vulnerable components. It is generally composed of lithium or beryllium as the main nuclear reaction layer (target material layer). The target must withstand severe thermomechanical, radiation, and hydrogen-induced damage conditions. Tantalum has a high hydrogen diffusion coefficient and can be used as a transition layer for neutron production targets in accelerator boron neutron capture therapy (AB-BNCT). A Ta film thickness of 20 μm is necessary to effectively prevent proton deposition and hydrogen embrittlement in the Cu substrate. There are many methods for preparing Ta films, such as vacuum plasma spraying (VPS), molten salt electroplating, chemical vapor deposition (CVD), and physical vapor deposition (PVD). Magnetron sputtering is chosen because of its advantages, including high sputtering speed, formation of dense films, excellent adhesion, precise control of film formation, and ability to cover a large surface area. However, the physical properties of Ta differ significantly from those of the copper substrate, making it prone to cracking and peeling once the film reaches a certain thickness.

[0004] The applicant initially attempted to design tantalum thin films as multilayer structures to reduce stress. While this method effectively reduced the thickness of single-layer films, preventing cracking or detachment, it required constant replacement of sputtering targets during multilayer film construction, resulting in target waste. Therefore, it is necessary to explore more diverse approaches to address the aforementioned technical problems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a Ta-Ti binary hydrogen absorption transition layer for an accelerator neutron source target and its preparation method. This invention constructs a Ta-Ti binary hydrogen absorption transition layer on the substrate surface of an accelerator neutron source target using magnetron co-sputtering technology. This Ta-Ti binary hydrogen absorption transition layer exhibits low residual internal stress, high adhesion to the substrate, and is not prone to cracking or detachment. Furthermore, the method of this invention is simple, requires no target replacement, and has high sputtering efficiency.

[0006] The specific technical solution of this invention is as follows:

[0007] In a first aspect, the present invention provides a Ta-Ti binary hydrogen absorption transition layer for an accelerator neutron source target, which is deposited on the surface of a substrate by magnetron co-sputtering technology. The Ta-Ti binary hydrogen absorption transition layer includes uniformly distributed tantalum and titanium; the mass ratio of tantalum to titanium is 80:20-90:10 (more preferably 85:15-90:10).

[0008] In the field of neutron source target systems, Ti is mainly used as a protective layer material on the surface of the target layer. This invention discovers that when Ti is doped into tantalum films, at low doping levels, titanium atoms are key sites for atomic bond angle distortion, which can significantly reduce the residual stress of the tantalum film. Furthermore, this invention also finds that titanium has good adhesion to substrates of almost all materials. Therefore, under these multiple factors, depositing a Ti-Ta binary hydrogen-absorbing transition layer on the substrate surface is expected to improve the film-substrate adhesion.

[0009] This invention deposits a Ta-Ti binary hydrogen-absorbing transition layer on the substrate surface via magnetron co-sputtering. The appropriate amount of Ti doping can promote the refinement of tantalum film grains and significantly reduce the residual internal stress of the tantalum film, thereby improving its film-substrate adhesion and thermal conductivity.

[0010] Furthermore, this invention reveals that the ratio of Ta to Ti in the Ta-Ti binary hydrogen-absorbing transition layer significantly affects the morphology and phase composition of the coating. Appropriate Ti atom doping in the Ta film can refine the grain size, and Ti's physical properties are closer to those of the substrate (e.g., Cu) than Ta's; introducing an appropriate amount of Ti atoms can effectively improve the bonding strength. Unlike traditional single-element coatings, co-sputtering preparation results in a more chaotic atomic arrangement. Each element is interrupted by a second element before forming a continuous film, resulting in only extremely small grains. The higher the degree of chaos, the denser the atomic packing. Therefore, the Ti doping amount needs to be strictly controlled. If the Ti content is too low, the improvement effect is not significant; if the Ti content is too high, excessive Ti doping leads to an increase in precipitated phases in the film, negatively impacting the film's corrosion resistance.

[0011] Preferably, the thickness of the Ta-Ti binary hydrogen absorption transition layer is 1-30 micrometers (more preferably 20-30 micrometers).

[0012] The present invention incorporates Ti into the tantalum film, which enables the transition layer to maintain good bonding strength with the substrate surface even when it is relatively thick (generally, the thicker the transition layer, the higher the residual internal stress and the worse the bonding strength with the substrate).

[0013] Secondly, the present invention provides a method for preparing the Ta-Ti binary hydrogen absorption transition layer of the above-mentioned accelerator source target, comprising:

[0014] S1: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine respectively; fix the substrate on the moving fixture trolley, introduce inert gas (preferably argon) into the sputtering chamber, and close the sputtering chamber.

[0015] S2: Adjust the gas pressure in the sputtering chamber to 0.5-2 Pa (more preferably 0.5-1 Pa), adjust the sputtering power of the Ta target and Ti target to 200-400 W (more preferably 300-400 W) and 50-200 W (more preferably 100-200 W) respectively, and the duty cycle to 30-90% (more preferably 60-90%) respectively, perform magnetron co-sputtering coating, control the moving fixture carriage to move back and forth between the Ta target and Ti target at a moving speed of 5-30 mm / s (more preferably 15-20 mm / s), and after coating, construct a Ta-Ti binary hydrogen absorption transition layer on the substrate surface.

[0016] This invention utilizes magnetron co-sputtering to ionize an inert gas, such as argon, under an electric field. The ionized argon ions bombard the surfaces of Ta and Ti targets, sputtering a large number of target atoms that deposit on the substrate surface. This invention also allows for the control of atomic ratios and phase structure in the Ta-Ti binary hydrogen-absorbing transition layer by adjusting sputtering power and carriage speed.

[0017] The base metal (e.g., commonly used Cu) typically has a significantly different melting point from Ta, resulting in the absence of intermetallic compounds under thermal equilibrium conditions. Furthermore, the large differences in thermal expansion coefficients, atomic radii, and electronegativity between Cu and Ta limit their solid solution diffusion capabilities, leading to limited adhesion between the Ta coating and the Cu substrate. The Ti atom content largely determines the film quality, and various stable compounds exist with varying compositions. Ti exhibits excellent corrosion resistance under various environments, which is beneficial for improving the adhesion between coatings. This invention discovers that under the aforementioned specific preferred sputtering conditions, an ideal amount of Ti can be introduced during co-deposition. The introduced Ti atoms disrupt Ta grain growth, thereby achieving grain refinement and strengthening. The resulting film exhibits a higher degree of Ti and Ta disorder; higher disorder leads to more grain boundaries and a degree of stress relief.

[0018] Preferably, in S1, the distance between the Ta target and the Ti target is 10-30 cm, and the distance between the Ta target and the sputtering chamber inlet is less than the distance between the Ti target and the sputtering chamber inlet.

[0019] Preferably, in S1, the reciprocating direction of the moving clamp trolley is parallel to the straight line formed by the Ta target and the Ti target, and the distance between them is 10-30cm; the starting point and the ending point of the reciprocating movement are flush with the Ta target and the Ti target, respectively.

[0020] Preferably, the substrate is made of copper, vanadium, tungsten, gold, platinum, lead, or alloys thereof.

[0021] Preferably, the electrolytic surface treatment method involves immersing the cathode and the substrate (which serves as the anode) in an acid solution for electrolytic treatment; the temperature is 30–50°C, and the current density is 5–50 mA·cm⁻¹. -2 The electrolysis time is 1–10 minutes. More preferably, the electrolysis temperature is 30–40°C, and the current density is 5–20 mA·cm⁻¹. -2 The time is 1 to 5 minutes. More preferably, the acid solution is a 75 to 85 wt% phosphoric acid solution.

[0022] Preferably, the laser surface treatment method involves laser treatment of the substrate surface using a parallel laser scanning method; 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. More preferably, the laser power is 10-20W, the pulse duration is 0-80ns, the laser line spacing is 5-20μm, and the scanning speed is 50-500mm / s.

[0023] Preferably, the Ta target and Ti target are pre-sputtered before co-sputtering: the sputtering chamber is closed, a vacuum is drawn, and then an inert gas (preferably argon) is introduced for pre-sputtering.

[0024] Preferably, during the pre-sputtering process, the vacuum is evacuated to a pressure ≤5×10⁻⁶ in the sputtering chamber. -8 After Pa, an inert gas (preferably argon) is introduced for pre-sputtering. Preferably,

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] (1) In this invention, a Ta-Ti binary hydrogen absorption transition layer is deposited on the substrate surface by magnetron co-sputtering. The appropriate amount of Ti doping can promote the refinement of tantalum film grains and significantly reduce the residual internal stress of tantalum film, thereby improving its film-substrate bonding and thermal conductivity.

[0027] (2) This invention utilizes magnetron co-sputtering to ensure good mechanical properties of the coating. By controlling the sputtering process conditions and adjusting the Ti content, the microstructure is refined, and the resulting Ta-Ti binary hydrogen absorption transition layer has the advantages of high density and uniform film formation.

[0028] (3) The production process of the present invention has good repeatability, fast deposition rate, and high process controllability, and is easy to industrialize. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the principle of magnetron co-sputtering of the present invention (left is a front view, right is a side view);

[0030] Figure 2 This is a schematic diagram (rendered image) illustrating the principle of magnetron co-sputtering in this invention;

[0031] Figure 3 This is a scanning electron microscope image of the thin film after coating in Comparative Example 1 of the present invention;

[0032] Figure 4 This is a scanning electron microscope (SEM) image of the thin film after coating in Comparative Example 2 of the present invention;

[0033] Figure 5 This is a scanning electron microscope (SEM) image of the thin film after coating in Example 1 of the present invention;

[0034] Figure 6 This is a scanning electron microscope (SEM) image of the thin film after coating in Example 2 of the present invention;

[0035] Figure 7 This is a scanning electron microscope (SEM) image of the thin film after coating in Example 3 of the present invention;

[0036] Figure 8 This is a scanning electron microscope (SEM) image of the thin film after coating in Example 4 of the present invention;

[0037] Figure 9 This is a scanning electron microscope image of the thin film after coating in Comparative Example 3 of the present invention;

[0038] Figure 10 This is a scanning electron microscope (SEM) image of the thin film after coating in Example 5 of the present invention;

[0039] Figure 11 This is a scanning electron microscope (SEM) image of the thin film after coating in Example 6 of the present invention;

[0040] Figure 12 This is a scanning electron microscope (SEM) image of the thin film after coating in Example 7 of the present invention.

[0041] Reference numerals: Ta target 1, moving clamp trolley 2, Ti target 3. Detailed Implementation

[0042] The present invention will be further described below with reference to embodiments.

[0043] General Implementation Examples

[0044] An accelerator neutron source target Ta-Ti binary hydrogen absorption transition layer is deposited on the substrate surface by magnetron co-sputtering technology. The Ta-Ti binary hydrogen absorption transition layer includes uniformly distributed tantalum and titanium; the mass ratio of tantalum to titanium is 80:20-90:10.

[0045] In some specific embodiments, the mass ratio of tantalum to titanium is further preferably in the range of 85:15-90:10.

[0046] In some specific embodiments, the thickness of the Ta-Ti binary hydrogen absorption transition layer ranges from 1 to 30 micrometers (more preferably 20 to 30 micrometers).

[0047] A method for preparing the Ta-Ti binary hydrogen absorption transition layer of the neutron source target in the above-mentioned accelerator includes:

[0048] S1: As Figure 1 and Figure 2 As shown, Ta target 1 and Ti target 3 are respectively installed on two target positions of the magnetron sputtering coating machine; the substrate is fixed on the moving fixture trolley 2, inert gas (preferably argon) is introduced into the sputtering chamber, and the sputtering chamber is closed.

[0049] In some specific embodiments, the substrate is made of copper, vanadium, tungsten, gold, platinum, lead, or alloys thereof.

[0050] In some specific embodiments, in S1, the distance between the Ta target and the Ti target is 10-30 cm. Figure 1 In a), the distance between the Ta target and the sputtering chamber inlet is less than the distance between the Ti target and the sputtering chamber inlet.

[0051] In some specific embodiments, in S1, the reciprocating direction of the moving clamp trolley is parallel to the straight line formed by the Ta target and the Ti target, and the distance between them is 20cm. Figure 1 (b) The starting and ending points of the reciprocating displacement are aligned with the Ta target and Ti target, respectively.

[0052] S2: Adjust the gas pressure in the sputtering chamber to 0.5-2 Pa, adjust the sputtering power of the Ta target and Ti target to 200-400 W and 50-200 W respectively, and the duty cycle to 30-90%. Perform magnetron co-sputtering coating. Control the moving fixture carriage to move back and forth between the Ta target and Ti target at a moving speed of 5-30 mm / s. After coating, a Ta-Ti binary hydrogen absorption transition layer is formed on the substrate surface.

[0053] In some specific embodiments, in S2, the air pressure in the sputtering chamber is adjusted to 0.5-1 Pa, the sputtering power of the Ta target and the Ti target is adjusted to 300-400 W and 100-200 W respectively, the duty cycle is 60-90%, and the moving speed of the moving fixture trolley is 15-20 mm / s.

[0054] In some specific embodiments, the electrolytic surface treatment method is as follows: immersing the cathode and the substrate serving as the anode in an acid solution for electrolytic treatment; the temperature is 30–50°C, and the current density is 5–50 mA·cm². -2 The electrolysis time is 1–10 minutes. More preferably, the electrolysis temperature is 30–40°C, and the current density is 5–20 mA·cm⁻¹. -2 The time is 1 to 5 minutes. More preferably, the acid solution is a 75 to 85 wt% phosphoric acid solution.

[0055] In some specific embodiments, the laser surface treatment method is as follows: the substrate surface is treated with a parallel laser scanning method; 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. More preferably, the laser power is 10-20W, the pulse duration is 0-80ns, the laser line spacing is 5-20μm, and the scanning speed is 50-500mm / s.

[0056] In some specific embodiments, the Ta target and Ti target undergo pre-sputtering before co-sputtering: the sputtering chamber is closed, a vacuum is drawn, and then an inert gas is introduced for pre-sputtering.

[0057] In some more specific embodiments, during the pre-sputtering process, the vacuum is evacuated until the gas pressure in the sputtering chamber is ≤5×10⁻⁶. -8 After Pa, inert gas is introduced for pre-sputtering for 5-15 minutes.

[0058] Specific embodiments and comparative examples

[0059] Comparative Example 1

[0060] Surface pretreatment of the substrate: A 10*10*1mm copper sheet was used as the substrate and sanded with 80-grit sandpaper for 5 minutes. Then, it was further polished with 200-grit and 400-grit sandpaper for 5 minutes each. Finally, the substrate was cleaned with acetone, alcohol and ultrapure water for 5 minutes each and then placed in a vacuum drying oven to dry for 1 hour.

[0061] Installation: Install the Ta target on the target position of the magnetron sputtering coating machine (with the distance between the Ta target and the sputtering chamber inlet being 50cm); attach the substrate to the stainless steel plate and install it on the fixture of the magnetron sputtering equipment.

[0062] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0063] Formal sputtering: Single tantalum was deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour).

[0064] Obtained by scanning electron microscopy Figure 3 As can be seen from the figure, the thin film has cracked and peeled off over a large area, exposing the copper substrate.

[0065] Comparative Example 2

[0066] Substrate surface pretreatment: Same as comparative example 1.

[0067] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0068] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0069] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 50W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 15mm / s).

[0070] Obtained by scanning electron microscopy Figure 4 The surface smoothness is very low, with a large number of particles aggregated and island-like structures present. Parts of the copper substrate are also exposed, and the film shows obvious cracks.

[0071] Example 1

[0072] Substrate surface pretreatment: Same as comparative example 1.

[0073] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0074] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0075] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 100W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 15mm / s).

[0076] Obtained by scanning electron microscopy Figure 5 As shown in the figure, the surface has low smoothness, with a large number of aggregates, and the particles are uniform in size and dispersed.

[0077] Example 2

[0078] Substrate surface pretreatment: Same as comparative example 1.

[0079] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0080] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0081] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 150W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 15mm / s).

[0082] Obtained by scanning electron microscopy Figure 6 It can be seen that the surface film has high flatness and few defects.

[0083] Example 3

[0084] Substrate surface pretreatment: Same as comparative example 1.

[0085] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0086] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0087] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 200W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 15mm / s).

[0088] Obtained by scanning electron microscopy Figure 7 As can be seen, the surface is relatively smooth, with only a small number of aggregated particles.

[0089] Example 4

[0090] Substrate surface pretreatment: Same as comparative example 1.

[0091] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0092] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0093] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 300W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 15mm / s).

[0094] Obtained by scanning electron microscopy Figure 8It can be seen that the surface has low flatness and some cracks exist.

[0095] Comparative Example 3

[0096] Substrate surface pretreatment: Same as comparative example 1.

[0097] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0098] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0099] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 300W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 1mm / s).

[0100] Obtained by scanning electron microscopy Figure 9 It is evident that the film exhibits significant cracking.

[0101] Example 5

[0102] Substrate surface pretreatment: Same as comparative example 1.

[0103] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0104] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0105] Co-sputtering: Tantalum and titanium were co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 300W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 5mm / s).

[0106] Obtained by scanning electron microscopy Figure 10 The surface shows poor smoothness, with some pits and film peeling. Additionally, some copper substrate is exposed, and the film exhibits obvious cracks.

[0107] Example 6

[0108] Substrate surface pretreatment: Same as comparative example 1.

[0109] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0110] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0111] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 300W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 20mm / s).

[0112] Obtained by scanning electron microscopy Figure 11 The surface appears relatively smooth.

[0113] Example 7

[0114] Substrate surface pretreatment: Same as comparative example 1.

[0115] Installation: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine (the distance between the Ta target and Ti target is 20cm, and the distance between the Ta target and Ti target and the sputtering chamber inlet is 50cm and 70cm respectively); attach the substrate to the stainless steel plate and fix it on the moving fixture trolley (the direction of the trolley's back-to-back movement is parallel to the straight line formed by the Ta target and Ti target, and the distance is 20cm; the start and end points of the back-to-back movement are flush with the Ta target and Ti target respectively).

[0116] Pre-sputtering: Close the sputtering chamber and evacuate until the gas pressure inside the sputtering chamber is ≥5×10⁻⁶. -8 Pa, then argon gas is introduced for pre-sputtering for 5 minutes.

[0117] Co-sputtering: Tantalum and titanium are co-deposited onto the substrate surface by magnetron sputtering (parameters: Ta target power 300W, duty cycle 90%, Ti target power 300W, duty cycle 90%, sputtering pressure 0.5Pa, sputtering time 1 hour, carriage moving speed 30mm / s).

[0118] Obtained by scanning electron microscopy Figure 12 The surface exhibits low smoothness, numerous aggregates, and island-like structures. Additionally, some copper substrate is exposed, and the film shows obvious cracks.

[0119] Performance Analysis

[0120] The magnetron co-sputtering process conditions and performance test results for each embodiment and comparative example are shown in the table below:

[0121]

[0122]

[0123] The data in the table above shows that:

[0124] In Comparative Examples 1-2 and Examples 1-4, the doping ratio of Ti in the thin film was adjusted by controlling the sputtering power of Ti-palladium. Data comparison revealed that Comparative Example 1 did not sputter Ti-palladium, resulting in a pure tantalum film. The film exhibited high stress and large-area cracking. In Comparative Examples 2 and Examples 1-4, as the Ti doping amount gradually increased, the film stress was significantly lower than in Comparative Example 1, indicating that Ti doping is beneficial for reducing film stress. Furthermore, Examples 1-4 showed better results than Comparative Example 2, Examples 2 and 3 were superior to Examples 1 and 4, with Example 2 being the best, exhibiting not only the lowest film stress but also the best film appearance.

[0125] In Examples 2, 3, and 5-7, the coating quality was controlled by adjusting the trolley's moving speed. Data comparison revealed that in Comparative Example 3, the slow trolley speed allowed sufficient time for tantalum grains to nucleate and grow, resulting in fewer grain boundaries and consequently higher film stress and a poorer film appearance. In Examples 5, 2, and 6, the film stress decreased with increasing trolley speed. However, in Example 7, increasing the speed to 30 mm / s led to a significant increase in film stress. Therefore, the optimal range is between that of Examples 2 and 6.

[0126] Example 8

[0127] The difference between Example 8 and Example 3 lies in the electrolytic treatment method used for substrate surface pretreatment:

[0128] (1) An 85 wt% phosphoric acid solution was used as the electrolyte solution and added to the electrolysis reactor. The electrolyte volume of the electrolysis reactor was 0.5 L.

[0129] (2) Immerse a 10*10*1mm copper sheet as the anode and a 30*30*1mm lead plate cathode directly into the electrolyte and fix their positions on the electrolysis reactor.

[0130] (3) Electrolytic pretreatment: Turn on the heating rod and observe the temperature with a thermometer. When the temperature rises to 40℃, turn on the power and set the current density to 20mA·cm. -2 The processing time was 5 minutes; finally, the copper substrate was cleaned with acetone, alcohol and ultrapure water for 5 minutes each, and then placed in a vacuum drying oven to dry for 1 hour.

[0131] After the above electrolytic pretreatment, a suitable number of discrete, discontinuous microporous structures with a size of 3-5 micrometers can be constructed on the substrate surface. Compared with ordinary rough surfaces, these special discontinuous microporous structures, in addition to increasing the surface roughness of the substrate (increasing the specific surface area), more importantly, are beneficial to the pinning effect of atomic sputtering during subsequent film deposition, which is more conducive to film-substrate bonding. At the same time, they can also play a better role in heat dissipation during thin film deposition. Furthermore, we found that in the later application and service of the target material, these microporous structures can also act as air buffers, which is beneficial to extending the target lifetime. Therefore, electrolytic surface treatment has more advantages than conventional surface treatment methods.

[0132] Example 9

[0133] The difference between Example 9 and Example 3 lies in the laser treatment method used for substrate surface pretreatment:

[0134] A 10*10*1mm copper sheet was used as the substrate. The laser parameters were set to 15W laser power, 15μm laser line spacing, 50ns pulse duration, 500mm / s scanning speed, and parallel laser scanning mode before surface treatment was performed on the copper sheet.

[0135] Because the surface after laser treatment 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 treatment, 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 trenches with widths of 30–60 micrometers along the laser scanning path. Furthermore, we found that this high-temperature melting followed by low-temperature solidification creates irregular micropores of approximately 5–30 micrometers on the surface of each trench. In subsequent magnetron sputtering, when high-energy particles reach the surface of the parallel trenches, these micropores can be better filled, thus improving the interlayer adhesion between the coating and the substrate. During long-term operation of the neutron source target, this micropore structure further facilitates heat dissipation and micro-area stress relief. Therefore, laser surface treatment offers significant advantages over conventional surface treatment methods.

[0136] 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.

[0137] 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 Ta-Ti binary hydrogen absorption transition layer for an accelerator neutron source target, characterized in that: The Ta-Ti binary hydrogen-absorbing transition layer is deposited on the substrate surface using magnetron co-sputtering technology. It comprises uniformly distributed tantalum and titanium, with a mass ratio of tantalum to titanium of 85:15-90:

10.

2. The Ta-Ti binary hydrogen absorption transition layer for the accelerator neutron source target according to claim 1, characterized in that: The thickness is 1-30 micrometers.

3. A method for preparing a Ta-Ti binary hydrogen absorption transition layer in an accelerator source target according to claim 1 or 2, characterized in that... include: S1: Install the Ta target and Ti target on the two target positions of the magnetron sputtering coating machine respectively; Fix the substrate onto the moving fixture trolley, introduce inert gas into the sputtering chamber, and then close the sputtering chamber; S2: Adjust the gas pressure in the sputtering chamber to 0.5-2Pa, adjust the sputtering power of the Ta target and Ti target to 200-400W and 50-200W respectively, and the duty cycle to 30-90%. Perform magnetron co-sputtering coating. Control the moving fixture carriage to move back and forth between the Ta target and Ti target at a moving speed of 15-20mm / s. After coating, a Ta-Ti binary hydrogen absorption transition layer is formed on the substrate surface.

4. The preparation method according to claim 3, characterized in that: In S2, the gas pressure in the sputtering chamber is adjusted to 0.5-1 Pa, and the sputtering power of the Ta target and Ti target is adjusted to 300-400 W and 100-200 W respectively, with duty cycles of 60-90% respectively.

5. The preparation method according to claim 3 or 4, characterized in that: In S1, The distance between the Ta target and the Ti target is 10-30 cm, and the distance between the Ta target and the sputtering chamber inlet is less than the distance between the Ti target and the sputtering chamber inlet; and / or The reciprocating direction of the moving clamp trolley is parallel to the straight line formed by the Ta target and the Ti target, with a distance of 10-30cm; the starting point and ending point of the reciprocating movement are flush with the Ta target and the Ti target, respectively.

6. The preparation method according to claim 3, characterized in that: The substrate is made of copper, vanadium, tungsten, gold, platinum, lead, or alloys thereof.

7. The preparation method according to claim 3, characterized in that: The substrate undergoes surface pretreatment: the substrate is surface treated, cleaned, and dried before use.

8. The preparation method according to claim 7, characterized in that: The surface treatment method is either electrolytic surface treatment or laser surface treatment.

9. The preparation method according to claim 8, characterized in that: The electrolytic surface treatment method is as follows: immersing the cathode and the substrate (which serves as the anode) in an acid solution for electrolytic treatment; the temperature is 30~50℃, and the current density is 5~50 mA·cm. -2 The time is 1 to 10 minutes.

10. The preparation method according to claim 8, characterized in that: The laser surface treatment method is as follows: the substrate surface is treated by laser using a parallel laser scanning method; 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.

11. The preparation method according to claim 3, characterized in that: The Ta and Ti targets undergo pre-sputtering before co-sputtering: the sputtering chamber is closed, a vacuum is drawn, and then an inert gas is introduced for pre-sputtering.

12. The preparation method according to claim 11, characterized in that: During the pre-sputtering process, the vacuum is evacuated until the gas pressure in the sputtering chamber is ≤5×10⁻⁶. -8 After Pa, inert gas is introduced for pre-sputtering.

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