A refractory metal Ta protective film resistant to liquid lead bismuth corrosion at high temperature and a preparation method thereof

Abstract

The application discloses a refractory metal Ta protective film resistant to liquid lead bismuth corrosion at high temperature and a preparation method thereof. The micron double-layer corrosion protection film TaO / Ta2O is generated on the surface of Ta by placing the metal Ta in static liquid lead bismuth at 570-608 DEG C for 20 hours. The protective film structure is compact, the bonding state between the oxidation film and the substrate is good, the dissolution and corrosion of the liquid lead bismuth alloy to the Ta substrate are blocked, the peeling of the oxidation film is prevented, and the corrosion resistance is high. The application provides an effective protection way for solving the serious corrosion problem of the refractory metal Ta at high temperature. Then, the corrosion mechanism of the refractory metal Ta in the liquid lead bismuth at high temperature is researched by analyzing the structure, thickness and compactness of the corrosion protection film, so as to lay a theoretical foundation for the engineering application of the refractory metal Ta in the nuclear industrial structural materials.

Description

Technical Field

[0001] This invention belongs to the technical field, specifically relating to a refractory metal Ta protective film resistant to corrosion by liquid lead and bismuth at high temperatures and its preparation method. Background Technology

[0002] Liquid lead-bismuth eutectic alloy (LBE) possesses excellent chemical and thermophysical properties, making it a preferred coolant and target material for fourth-generation lead-cooled reactors and accelerator-driven subcritical systems (ADS). Compared to other coolants, LBE offers significant advantages:

[0003] ① Liquid LBE has excellent homogenization properties, natural circulation capabilities, and stable performance;

[0004] ②LBE has good neutron performance;

[0005] ③LBE has high safety and economy;

[0006] ④LBE has good thermal conductivity;

[0007] ⑤LBE has relatively stable chemical properties.

[0008] Although liquid lead-bismuth alloy (LBE) has many advantages as a coolant, the corrosion of structural materials by LBE remains a key factor restricting the development of lead block cold reactors. Various protective measures must be adopted to prevent corrosion of structural materials and improve their service performance. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a refractory metal Ta protective film resistant to liquid lead-bismuth corrosion at high temperature and its preparation method, which addresses the shortcomings of the prior art. This invention solves the technical problem of the corrosion resistance of refractory metal Ta in LBE environment, improves the corrosion resistance of LBE structural materials, enhances their service performance, and lays a theoretical foundation for the engineering application of refractory metal Ta in nuclear industry structural materials.

[0010] The present invention adopts the following technical solution:

[0011] A method for preparing a refractory metal Ta protective film resistant to high-temperature liquid lead-bismuth corrosion involves placing Ta in liquid lead-bismuth and heating it to generate a Ta2O protective film. The outer side of the Ta2O protective film reacts with dissolved O diffused inward from the liquid lead-bismuth to generate a TaO protective film. The exposed TaO protective film reacts again with dissolved O diffused inward from the liquid lead-bismuth to generate a surface corrosion product, a Ta2O5 oxide film. The Ta2O5 oxide film gradually thickens and eventually powders and falls off, forming a dense TaO / Ta2O bilayer oxide film structure on the Ta surface.

[0012] Specifically, the heating reaction temperature is 570–608℃, and the holding time is 19.5–20.5 h.

[0013] Specifically, the thickness of the Ta2O protective film is 2–5 μm.

[0014] Specifically, the thickness of the TaO protective film is 8–10 μm.

[0015] Specifically, liquid lead-bismuth is as follows:

[0016] The temperature is controlled at 208–229℃ and the holding time is 78–98 min to completely melt the lead-bismuth alloy and obtain liquid lead-bismuth.

[0017] Furthermore, the mass of the lead-bismuth alloy is 400–500g.

[0018] Specifically, before being placed into liquid lead bismuth, Ta is first polished, cleaned, and sprued.

[0019] Specifically, the reaction equations for the preparation process are as follows:

[0020] 2Ta(s) + O(dissolved) → Ta₂O(s)

[0021] Ta2O(s)+O(dissolved)→2TaO(s)

[0022] 2TaO(s)+3O(dissolved)→Ta2O5(s)

[0023] Another technical solution of the present invention is a refractory metal Ta protective film that is resistant to corrosion by liquid lead and bismuth at high temperatures.

[0024] Specifically, the melting point of the refractory metal Ta protective film is greater than 1800℃.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] A method for preparing a refractory metal Ta protective film resistant to liquid lead-bismuth corrosion at high temperatures involves placing metallic Ta into a liquid lead-bismuth alloy, thereby generating a dense double-layer TaO / Ta2O protective film on the surface of metallic Ta, which improves the corrosion resistance of Ta metal against liquid lead-bismuth alloy.

[0027] Furthermore, metallic Ta is chemically stable, exhibiting very slight oxidation at 280-300℃ and significant oxidation at 500-600℃, forming a relatively good corrosion-resistant protective film. Therefore, the corrosion temperature was controlled at 570-608℃, the oxygen concentration was kept within the normal furnace atmosphere, and corrosion was carried out for 20 hours to ensure sufficient formation of a protective film on the Ta metal surface, thus verifying the relevant performance.

[0028] Furthermore, a TaO / Ta2O double protective film is formed on the Ta metal surface, with the inner Ta2O protective film having a thickness of approximately 2–5 μm.

[0029] Furthermore, the melting temperature of the lead-bismuth eutectic alloy is 208–229℃, and the holding time is 78–98 min, which allows the lead-bismuth alloy to melt completely, ensuring sufficient corrosion of Ta and guaranteeing the smooth progress of the experiment.

[0030] Furthermore, before the Ta metal test sample is placed into liquid lead bismuth, it must be polished to remove various oil stains, thereby ensuring the smoothness of the Ta metal and reducing experimental errors.

[0031] The refractory metal Ta protective film, which is resistant to corrosion by liquid lead-bismuth at high temperatures, has a relatively dense internal structure. The protective film prevents further oxidation of Ta and blocks the dissolution and erosion of the Ta matrix by the liquid lead-bismuth alloy. The oxide film has a good bond with the matrix, which can prevent the oxide film from peeling off and has high corrosion resistance.

[0032] In summary, this invention greatly improves the corrosion resistance of the Ta matrix, enhances its service performance, and lays a theoretical foundation for the engineering application of refractory metal Ta in structural materials of the nuclear industry.

[0033] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] Figure 1 SEM images of the sample cross-section taken 20 hours ago;

[0035] Figure 2 These are macroscopic morphological images of Ta samples before and after corrosion according to the present invention.

[0036] Figure 3 XRD pattern of powdered oxide film on Ta surface exposed to air;

[0037] Figure 4 SEM and EDS images of the etched interface of Ta after 20 h of etching in LBE;

[0038] Figure 5 EPMA analysis image of the corrosion interface of Ta after 20 h of corrosion in LBE;

[0039] Figure 6 Transmission and EDS images of the etched interface after Ta was etched in LBE for 20 hours. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0042] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0043] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0044] In this invention, unless otherwise specified, the components involved or their preferred components can be combined to form new technical solutions.

[0045] In this invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been listed in this document, and "6~22" is simply an abbreviation of these numerical combinations.

[0046] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0047] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0048] In this invention, unless otherwise stated, the various reaction or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0049] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0050] Metallic titanium (Ta) is a high-melting-point, irreplaceable refractory metal with advantages such as chemical stability, good ductility, and extremely strong corrosion resistance. At room temperature, Ta resists all inorganic acids except for HF (high-temperature hydroxide), and even HF corrosion of Ta is extremely slow. While Ta reserves in the Earth's crust are relatively small, its excellent resistance to liquid metal corrosion makes it a suitable structural material for the nuclear energy industry, where liquid metals serve as coolants. Ta forms a protective film with good corrosion resistance in liquid lead-bismuth alloys, providing a good solution to the corrosion problem of structural materials.

[0051] The method for preparing the refractory metal Ta protective film resistant to high-temperature liquid lead-bismuth corrosion according to the present invention is as follows:

[0052] S1. Cut the Ta bar into rectangular samples of 53mm×8mm×4mm. After sanding, cleaning with alcohol, and polishing, remove the wire cutting marks and oil stains from the sample surface.

[0053] S2. Place the lead-bismuth alloy (Pb 44.5 wt.%, Bi 55.5 wt.%) into a 50 ml alumina crucible. The melting temperature of the lead-bismuth alloy is 208-229℃, and the holding time is 78-98 min to ensure that the lead-bismuth alloy is completely melted.

[0054] The density of liquid lead bismuth is calculated using the following formula:

[0055] ρ LBE =11096-1.3236T

[0056] Where T is temperature, in K; ρ LBE The unit is kg / m³ 3 .

[0057] The required mass of lead-bismuth alloy is calculated to be 400–500 g according to the following formula:

[0058] M LBE =ρ LBE ·V LBE

[0059] Thermocouples are used to accurately measure the real-time temperature of liquid lead-bismuth to prevent the protective film from failing due to differences in reaction temperature.

[0060] S3. Place the sample treated in step S1 into the liquid lead-bismuth from step S2 and fix it. Raise the temperature to 570–608℃ and maintain it for 19.5–20.5 h. The oxygen concentration is the normal atmosphere inside the furnace. The Ta matrix undergoes cross-sectional and diffusion reactions with the dissolved oxygen in the liquid lead-bismuth alloy, first forming a protective film of Ta2O with a thickness of 2–5 μm. The outer side of Ta2O further reacts with dissolved O diffused inward from the liquid lead-bismuth to form TaO, with a protective film thickness of 8–10 μm. The TaO exposed on the outside reacts again with dissolved O diffused inward from the liquid lead-bismuth to form the outermost corrosion product Ta2O5. The Ta2O5 oxide film gradually thickens and then powders and falls off. The formed TaO / Ta2O double oxide film has a dense structure and is tightly attached to the Ta matrix. It has strong bonding and can prevent the oxide film from peeling off, thus having high corrosion resistance.

[0061] S4. Take out the experimental sample and cool it to obtain a refractory metal Ta with a corrosion-resistant protective film.

[0062] The protective film for the corrosion resistance of metallic Ta at high temperatures has a melting point greater than 1800℃.

[0063] S5. Testing and characterization of the protective film's performance, material type, thickness, density, etc.:

[0064] S501. Observe the corrosion morphology of the protective film and study the corrosion resistance of the protective film;

[0065] The formed TaO / Ta2O double oxide film is uniform and smooth, with a dense structure that adheres tightly to the Ta matrix, exhibiting strong bonding and preventing oxide film peeling, thus demonstrating high corrosion resistance. It effectively prevents O from corroding the Ta matrix and strongly blocks contact between the Ta matrix and the liquid lead-bismuth alloy, effectively improving the corrosion resistance of the refractory metal Ta.

[0066] The specific morphology of the protective film was observed and its composition was analyzed using a field emission scanning electron microscope (GeminiSEM500), a matching energy dispersive spectroscopy (EDS) instrument, and XRD. The atomic ratio of Ta and O was used to confirm the material of the protective film.

[0067] S502. The specific substances of the protective film on the surface of the corroded sample are detected by XRD and EDS, and the morphology of the protective film is observed by SEM.

[0068] The XRD 2θ range is 10–90°, the current is 200 mA, the voltage is 40 kV, and the scan rate is 2° / min.

[0069] S503. The sample is cold-mounted with epoxy resin to create an interface sample, which is then sanded and polished. The morphology of the interface protective film is characterized by SEM, EPMA and transmission electron microscopy (TEM), and the specific substances of the protective film are detected to obtain comprehensive information about the protective film.

[0070] The sample was cold-mounted with epoxy resin. The resulting interface sample was then gently sanded along the parallel direction of the interface with 1000#, 1200#, and 1500# SiC wet sandpaper, and polished with diamond polishing agent and woolen cloth to prevent the protective film of the interface from being damaged by human intervention.

[0071] The protective film prepared by the method of this invention solves the problems of severe oxidation of refractory metal Ta at high temperature and corrosion by liquid metal, improves the corrosion resistance of refractory metal Ta to liquid metal at high temperature, and reveals the corrosion mechanism of refractory metal Ta in liquid lead bismuth at high temperature.

[0072] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0073] Example 1

[0074] Refractory metal Ta in liquid lead-bismuth:

[0075] The impurity concentrations of the Ta rods and lead-bismuth alloys used in the experiment were detected by SEM-EDS, as shown in Tables 1 and 2.

[0076] Table 1 Chemical composition of refractory metal Ta (wt.%)

[0077]

[0078] Table 2. Impurity concentrations (ppm) in the original LBE.

[0079]

[0080] 1) Cut Ta rods into rectangular samples of 53mm×8mm×4mm using wire cutting. Lightly polish with 1000#, 1200#, and 1500# SiC wet sandpaper. Polish with a woolen polishing cloth and 2.5μm diamond polishing agent. Finally, ultrasonically clean with alcohol for 20 minutes and blow dry. The purpose of this is to remove contaminants adhering to the sample surface to avoid affecting the formation of the protective film and structural density.

[0081] 2) Weigh 400g of lead-bismuth alloy, ultrasonically clean it with alcohol for 20 minutes and blow it dry. This is to remove contaminants adhering to the surface of lead-bismuth. Place the weighed lead-bismuth alloy into a 50ml alumina crucible, raise the temperature inside the furnace to 208℃, and hold it for 78 minutes to completely melt the lead-bismuth alloy.

[0082] 3) The Ta sample was placed vertically into the crucible containing liquid lead-bismuth and secured with clamps to prevent tilting. The length of the sample penetrating the liquid lead-bismuth was approximately 25 mm. To ensure oxygen dissolution in the liquid lead-bismuth, the oxygen concentration inside the furnace was maintained at saturation, and the corrosion temperature was controlled at 570℃. The sample was removed after 19.5 hours. The sample cross-section was prepared as shown in the image. Figure 1 As shown, a smooth, dense TaO / Ta2O bilayer oxide film with good adhesion to the substrate can be observed. The total thickness of the bilayer oxide film is 10 μm, the thickness of the Ta2O protective film is 2 μm, and the thickness of the outer TaO protective film is 8 μm.

[0083] Example 2

[0084] Refractory metal Ta in liquid lead-bismuth:

[0085] 1) Cut Ta rods into rectangular samples of 53mm×8mm×4mm using wire cutting. Lightly polish with 1000#, 1200#, and 1500# SiC wet sandpaper. Polish with a woolen polishing cloth and 2.5μm diamond polishing agent. Finally, ultrasonically clean with alcohol for 24 minutes and blow dry. The purpose of this is to remove contaminants adhering to the sample surface to avoid affecting the formation of the protective film and structural density.

[0086] 2) Weigh 450g of lead-bismuth alloy, ultrasonically clean it with alcohol for 25 minutes and blow it dry. This is to remove contaminants adhering to the surface of lead-bismuth. Place the weighed lead-bismuth alloy into a 50ml alumina crucible, raise the temperature inside the furnace to 220℃, and hold it for 85 minutes to completely melt the lead-bismuth alloy.

[0087] 3) Place the Ta sample vertically into the crucible containing liquid lead-bismuth and secure it with clamps to prevent tilting. The length of the experimental sample penetrating the liquid lead-bismuth should be approximately 25 mm. To ensure oxygen dissolves in the liquid lead-bismuth, maintain the oxygen concentration in the furnace at saturation, control the corrosion temperature at 600℃, and remove the sample after 20 hours. The sample cross-section is obtained through cross-sectional sample preparation as shown below. Figure 1 As shown, a smooth, dense TaO / Ta2O bilayer oxide film with good adhesion to the substrate can be observed. The total thickness of the bilayer oxide film is 13 μm, the thickness of the Ta2O protective film is 4 μm, and the thickness of the outer TaO protective film is 9 μm.

[0088] Example 3

[0089] Refractory metal Ta in liquid lead-bismuth:

[0090] 1) Cut Ta rods into rectangular samples of 53mm×8mm×4mm using wire cutting. Lightly polish with 1000#, 1200#, and 1500# SiC wet sandpaper. Polish with a woolen polishing cloth and 2.5μm diamond polishing agent. Finally, ultrasonically clean with alcohol for 30 minutes and blow dry. The purpose of this is to remove contaminants adhering to the sample surface to avoid affecting the formation of the protective film and structural density.

[0091] 2) Weigh 500g of lead-bismuth alloy, ultrasonically clean it with alcohol for 30 minutes and blow it dry. This is to remove contaminants adhering to the surface of lead-bismuth. Place the weighed lead-bismuth alloy into a 50ml alumina crucible, raise the temperature inside the furnace to 229℃, and hold it for 98 minutes to completely melt the lead-bismuth alloy.

[0092] 3) The Ta sample was placed vertically into the crucible containing liquid lead-bismuth and secured with clamps to prevent tilting. The length of the sample penetrating the liquid lead-bismuth was approximately 25 mm. To ensure oxygen dissolution in the liquid lead-bismuth, the oxygen concentration inside the furnace was maintained at saturation, and the corrosion temperature was controlled at 608℃. The sample was removed after 20.5 hours. The sample cross-section was prepared as shown in the image. Figure 1 As shown, a smooth, dense TaO / Ta2O bilayer oxide film with good adhesion to the substrate can be observed. The total thickness of the bilayer oxide film is 15 μm, the thickness of the Ta2O protective film is 5 μm, and the thickness of the outer TaO protective film is 10 μm.

[0093] Verification Example

[0094] Testing and characterization of the material type and structure of the surface protective film:

[0095] 1) such as Figure 2As shown, a thick lead-bismuth coating was observed on the sample surface. Severe corrosion was clearly visible after 20 hours of corrosion. The refractory metal Ta sample, after 20 hours of corrosion, was treated by gently grinding the surface with 1000# sandpaper to remove the lead-bismuth coating. XRD analysis was then performed, and the results are shown below. Figure 3 As shown, only Ta₂O₅ was present. After gently polishing the Ta sample with sandpaper, XRD analysis was performed again, and the results were as follows. Figure 3 As shown, the test results indicate the presence of Ta2O and TaO, proving that a multilayer oxide film of low-valence Ta oxides, with an outer layer of Ta2O5 and an inner layer of TaO / Ta2O, was formed on the surface of the Ta sample.

[0096] 2) The Ta interface sample, after being etched in a static saturated oxygen liquid LBE at 600℃ for 20 hours, was subjected to SEM images and EDS surface distribution maps of the Ta corrosion interface using a field emission scanning electron microscope and its associated energy dispersive spectrometer, as shown below. Figure 4 As shown, the protective film is dense and uniform, and well bonded to the substrate, effectively preventing oxygen penetration and Ta oxidation. Furthermore, the protective film prevents direct contact between the Ta substrate and the lead-bismuth solution, blocking the corrosion of the Ta substrate by the lead-bismuth solution. However, in the outermost detached area of ​​the protective film, the LBE coating layer still contains some Ta oxides, scattered in fragments. This suggests that the outermost oxide film of the Ta sample is loose and fragile. Figure 3 The XRD results suggest that the outermost Ta2O5 oxide film is prone to pulverization and breakage.

[0097] 3) The Ta interface sample, after being etched in a static saturated oxygen liquid LBE at 600℃ for 20 hours, was analyzed using electron probe microanalysis (EPMA). Figure 5 As shown in Table 3, the atomic ratio of Ta and O in the EPMA analysis of the central protective film is approximately 1:1, indicating that the composition of the dense protective film in the middle is TaO.

[0098] Table 3. Atomic percentages of elements in the protective film of the middle layer as determined by EPMA.

[0099]

[0100] 4) Figure 6 The oxide film observed under a transmission electron microscope is shown in Table 4. Based on the atomic ratio of Ta and O at the bottom of the oxide film determined by EDS analysis, Ta:O≈2:1. The protective film at the bottom, which is well bonded to the substrate and is dense, is composed of Ta2O.

[0101] Table 4. Figure 6 EDS analysis of the atomic percentage of each element in the bottom protective film

[0102]

[0103] 5) In the corrosion of refractory metal Ta in liquid lead-bismuth at 600℃, it first reacts with oxygen dissolved in the liquid lead-bismuth to form Ta2O. Ta2O further reacts with O to form TaO. TaO continues to react with oxygen to form Ta2O5. The Ta2O5 oxide film is easily powdered and peeled off, eventually forming a TaO / Ta2O double protective film. The reaction equation is as follows:

[0104] 2Ta(s) + O(dissolved) → Ta₂O(s)

[0105] Ta2O(s)+O(dissolved)→2TaO(s)

[0106] 2TaO(s)+3O(dissolved)→Ta2O5(s)

[0107] In summary, this invention provides a high-temperature resistant protective film of refractory metal Ta (Ta) resistant to liquid lead-bismuth corrosion and its preparation method. By placing metallic Ta in static liquid lead-bismuth at 570-608℃ for 20 hours, a micron-sized double-layer anti-corrosion protective film, TaO / Ta2O, is generated on the Ta surface. The protective film has a dense structure and a good bond between the oxide film and the substrate, preventing the liquid lead-bismuth alloy from dissolving and eroding the Ta substrate. It also prevents the oxide film from peeling off and exhibits high corrosion resistance. This provides an effective protective approach to solve the severe corrosion problem of refractory metal Ta at high temperatures. By analyzing the structure, thickness, and density of the anti-corrosion protective film, the corrosion mechanism of refractory metal Ta in liquid lead-bismuth at high temperatures is studied, laying a theoretical foundation for the engineering application of refractory metal Ta in structural materials in the nuclear industry.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a refractory metal Ta protective film resistant to corrosion by liquid lead and bismuth at high temperatures, characterized in that, Ta rods were wire-cut into rectangular samples of 53mm × 8mm × 4mm. These samples were then successively polished along the interface parallel to the surface using 1000#, 1200#, and 1500# SiC wet sandpaper. Polishing was performed using a woolen polishing cloth and 2.5μm diamond polishing compound. Finally, the samples were ultrasonically cleaned with alcohol. The Ta was then placed in liquid lead-bismuth and heated to react, generating a 2-5μm thick Ta₂O protective film. The liquid lead-bismuth consisted of: The temperature is controlled at 208~229℃ and the holding time is 78~98min to completely melt the lead-bismuth alloy and obtain liquid lead-bismuth. The outer side of the Ta2O protective film reacts with dissolved O that diffuses inward from the liquid lead bismuth to form a TaO protective film with a thickness of 8~10μm. The exposed TaO protective film reacts again with dissolved O diffused inward from the liquid lead bismuth, generating a surface corrosion product, Ta2O5 oxide film. The Ta2O5 oxide film gradually thickens and then powders and falls off, forming a dense TaO / Ta2O double oxide film structure on the Ta surface.

2. The method for preparing a refractory metal Ta protective film resistant to liquid lead-bismuth corrosion at high temperature according to claim 1, characterized in that, The heating reaction temperature is 570~608℃, and the holding time is 19.5~20.5h.

3. The method for preparing a refractory metal Ta protective film resistant to liquid lead-bismuth corrosion at high temperatures according to claim 1, characterized in that, The mass of the lead-bismuth alloy is 400~500g.

4. A refractory metal Ta protective film resistant to liquid lead-bismuth corrosion at high temperatures, prepared by the method according to claim 1, 2, or 3.

5. The refractory metal Ta protective film resistant to liquid lead-bismuth corrosion at high temperatures according to claim 4, characterized in that, The melting point of the protective film of refractory metal Ta is greater than 1800℃.

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