Screening method and application of liquid lead bismuth corrosion resistant material based on sandwich structure

Abstract

The invention discloses a screening method and application of a liquid lead bismuth corrosion resistant material based on a sandwich structure. The outer layer of the sandwich structure is a target component film, and the interlayer is a lead-bismuth alloy film. The screening method comprises the following steps: S1, preparing a sandwich structure composite film material; s2, in-situ corrosion of liquid lead and bismuth of the composite film material; and S3, characterizing the corroded composite film material, and judging the liquid lead and bismuth corrosion resistance of the target component in the composite film material according to the characterization result. A sandwich structure film sample is prepared by utilizing a magnetron sputtering technology, the oxygen content of sandwich lead bismuth alloy is regulated and controlled by controlling the atmosphere in the deposition process, a corrosion interface of liquid lead bismuth and a test material is explored by adopting in-situ heating, and the problems that oxygen atoms are adsorbed on the surface of the sample, the oxygen content in the liquid lead bismuth cannot be precisely regulated and controlled and the like are solved. The corrosion performance of the material in oxygen-controlled liquid lead bismuth can be rapidly and efficiently obtained, and the method has important significance on rapid screening of novel lead bismuth corrosion resistant materials.

Description

Technical Field

[0001] The present invention relates to the technical field of materials resistant to liquid lead-bismuth corrosion, and particularly relates to a screening method and application of a material resistant to liquid lead-bismuth corrosion based on a sandwich structure. Background Art

[0002] A lead-cooled fast reactor (LFR) is a nuclear reactor that uses lead or a lead alloy as a coolant and belongs to the fourth generation of nuclear reactors. The coolant of the lead-cooled fast reactor is a liquid lead-bismuth eutectic alloy (LBE). Liquid lead-bismuth has excellent neutronics performance, chemical inertness, thermophysical properties, and anti-irradiation performance, etc., making the lead-cooled fast reactor have inherent safety. However, at high temperatures, liquid lead-bismuth will undergo corrosion processes such as dissolution, oxidation, and erosion with steel structure materials. Therefore, it is necessary to study the compatibility of materials in liquid lead-bismuth coolant and find materials resistant to liquid lead-bismuth corrosion.

[0003] Some patent documents provide coating materials for improving the corrosion resistance of liquid lead-bismuth. For example, patent CN116043155A discloses a composite coating resistant to liquid lead-bismuth erosion-corrosion. In this patent, an FeCrAlY coating is sprayed on the surface of the substrate, and the FeCrAlY coating is remelted and polished, and then the coating is pre-oxidized; by spraying an FeCrAlY coating on the surface of the substrate and then remelting the FeCrAlY coating, the interlayer interface between the particles inside the FeCrAlY coating disappears, achieving the effect of sealing pores; the polishing treatment can polish the coating on the surface of the substrate flat. When the liquid lead-bismuth eutectic alloy flows and circulates to cool down, it reduces the erosion-corrosion effect on the coating and improves the service life of the coating; finally, pre-oxidation treatment is carried out on the surface of the coating, and a continuous and dense thermally grown oxide layer is in-situ generated on the surface of the coating, which can effectively reduce the wettability with the liquid lead-bismuth alloy and improve the long-term service stability. Another example is that patent CN117385252A discloses a high-entropy alloy coating resistant to lead-bismuth corrosion. The present invention selects laser cladding and laser remelting technologies to synergistically prepare an FeCrMnVY high-entropy alloy coating. This coating is a body-centered cubic BCC phase solid solution structure, and this coating has good high-temperature corrosion resistance to lead-bismuth.

[0004] Currently, the main method for studying the corrosion behavior of materials in a liquid lead-bismuth environment is static immersion, that is, immersing the experimental material samples in high-temperature liquid lead-bismuth and testing the corrosion performance of the materials after soaking for a certain period of time. This kind of corrosion test is generally carried out under an oxygen-controlled state, and different oxygen concentrations and corrosion temperatures have a great influence on the corrosion behavior of the materials. The oxygen control process uses a method of introducing oxygen or argon to regulate the oxygen content in the liquid lead-bismuth.

[0005] Patent CN111693449A discloses a telescopic corrosion kettle and a liquid lead-bismuth alloy corrosion test method. The corrosion kettle includes a frame and a test kettle with the kettle mouth facing upward. It also includes a specimen hanger with its upper end fixed to the frame and its lower end for fixing specimens. It is characterized in that it further includes a lifting device, the output end of the lifting device is connected to the test kettle, and the lifting device is used to drive the test kettle to move up and down. It also includes a displacement sensor installed on the frame, and the displacement sensor is used to detect the displacement of the test kettle in the vertical direction. The test method is based on the corrosion kettle. The structural design of the corrosion kettle and the test method can solve the problems of judging the position of specimens in the lead-bismuth alloy melt and the corrosion problems brought to corresponding detection devices. Patent CN116626100A relates to a heat transfer experiment device and an experiment method. To solve the problem that the existing experimental device cannot meet the research requirements of the flow and heat transfer characteristics of lead-bismuth alloy in a rectangular narrow channel, the flow direction of the lead-bismuth alloy inside the experimental section is from top to bottom. The inlet and outlet cylindrical chambers and the rectangular variable diameter of the experimental section are fixed by welding and an external mechanical fixing device. The rectangular narrow channel is composed of stainless steel thin plates. The inner side of the narrow side of the channel is supported and sealed at the first level by stainless steel pads, and the outer side is supported and fixed at the second level by bolt connection of stainless steel fixing pads. High-temperature sealant is applied between the stainless steel pads and bolts and bolt gaps to achieve the third-level seal. The thin plate of the rectangular narrow channel is heated by an indirect electric heating method. This invention is used for the flow and heat transfer experiment of lead-bismuth alloy.

[0006] However, the above test methods have the disadvantages and deficiencies of complex devices, great difficulty in oxygen control, long experimental periods, and the need to spend a large amount of time and costs. Therefore, there is an urgent need to develop a test method with the advantages of simplicity, easy operation, and low cost. Summary of the Invention

[0007] Traditional liquid lead-bismuth corrosion test methods have the problems of complex devices, great difficulty in oxygen control, long experimental periods, and the need to spend a large amount of time and costs. To solve the above problems, the purpose of the present invention is to provide a screening method and its application of liquid lead-bismuth corrosion-resistant materials based on a sandwich structure, which is convenient to operate, has a short test time, and can better solve the above problems. Through this method, the oxygen content in liquid lead-bismuth can be controlled, high vacuum can be achieved, and the dissolution corrosion situation between the test sample and liquid lead-bismuth can be quickly obtained, thus facilitating the study of the corrosion behavior of materials.

[0008] In the present invention, a thin film sample to be tested and a lead-bismuth alloy layer are prepared in a high-vacuum magnetron sputtering system, and in-situ liquid lead-bismuth corrosion technology is used to conduct high-temperature corrosion tests to study the corrosion process between the material and liquid lead-bismuth, and then a new type of material resistant to liquid lead-bismuth corrosion is screened out.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] One of the technical solutions of the present invention provides a composite film material with a sandwich structure; the sandwich structure includes two outer layers and an intermediate sandwich layer, both outer layers are target component films, and the intermediate sandwich layer is a lead-bismuth alloy film.

[0011] Further, the thickness of each layer of the composite film material with a sandwich structure is 0.5 - 2 μm.

[0012] Another technical solution of the present invention provides a screening method for a liquid lead-bismuth corrosion-resistant material based on the above composite film material with a sandwich structure, including the following steps:

[0013] S1. Prepare a composite film material sample with a sandwich structure;

[0014] S2. Transfer the above composite film material sample to a heated substrate for in-situ corrosion with liquid lead-bismuth;

[0015] S3. Characterize and analyze the composite film material sample after in-situ corrosion, and judge whether the target component in the composite film material sample has good liquid lead-bismuth corrosion resistance according to the characterization results.

[0016] Further, the preparation of the composite film material sample with a sandwich structure in step S1 is carried out in a magnetron sputtering device; the preparation process is as follows:

[0017] First, prepare a single-layer target component film sample; deposit a layer of lead-bismuth alloy film on the single-layer target component film sample to obtain a target component film / lead-bismuth alloy film sample; deposit a layer of target component film sample on the target component film / lead-bismuth alloy film sample to obtain a sandwich structure of target component film / lead-bismuth alloy film / target component film, which is the composite film material sample with a sandwich structure;

[0018] Among them, in the first layer and the third layer, the preparation method conditions of the target component film sample are the same.

[0019] Further, when preparing the composite thin film material sample with a sandwich structure in step S1, the substrate of the magnetron sputtering device rotates, and the rotation speed is 5-10 r / min; the purity of the target used in the magnetron sputtering is greater than 99.95%, preferably greater than 99.99%; the magnetron sputtering is carried out in an inert gas atmosphere, and the inert gas atmosphere is preferably an Ar atmosphere, and the gas flow rate of the Ar atmosphere is in the range of 40-60 sccm; the working pressure of the magnetron sputtering is 0.5-1.5 Pa, the sputtering power is 30-130 W, and the sputtering time is 1-15 min; the distance between the target used in the magnetron sputtering and the substrate of the magnetron sputtering device is 4-8 cm; in the chamber of the magnetron sputtering device, the base pressure is regulated to below 1.5×10 -3 Pa by a molecular pump, and 40-60 sccm of pure argon gas and 0-30 sccm of a mixed gas of argon and oxygen are introduced, and the oxygen content is controlled by the ratio of the pure argon gas and the mixed gas of argon and oxygen.

[0020] Furthermore, the method for preparing the single-layer target component thin film sample in step S1 is: using any one of a single crystal silicon wafer or a stainless steel sheet as the substrate, and controlling the sputtering conditions of the target component material target as: the argon gas flow rate is 30-60 sccm, the base pressure is 1.5×10 -3 ~9.0×10 -4 Pa, the sputtering pressure is 1.0-1.4 Pa, and the target power is 30-150 W.

[0021] Furthermore, the method for depositing a lead-bismuth alloy film on the single-layer target component thin film sample in step S1 is: reducing the sputtering chamber to the target vacuum degree, controlling the gas flow rate during the sputtering process, so as to control the oxygen concentration in the deposited lead-bismuth alloy, and depositing a lead-bismuth alloy film on the surface of the thin film sample; the lead-bismuth alloy is sputtered by a liquid lead-bismuth target, and the liquid lead-bismuth target is a lead-bismuth eutectic alloy.

[0022] Furthermore, the steps of sputtering and depositing another single-layer target component thin film sample (the third layer) on the target component thin film / lead-bismuth alloy film are the same as the conditions for preparing the single-layer target component thin film sample (the first layer).

[0023] Further, the method for performing in-situ corrosion testing of the composite thin film material sample with liquid lead-bismuth in step S2 is: first transferring the composite thin film material sample (the sample deposited with the lead-bismuth alloy film layer) to a heating substrate, introducing a small amount of inert gas (preferably high-purity argon gas), and then preheating the heating substrate of the magnetron sputtering device to the temperature required for in-situ corrosion, and after corroding for a certain time, transferring and taking out the substrate.

[0024] In a specific embodiment of the present invention, when performing in-situ corrosion testing on a liquid lead-bismuth alloy, a composite film material sample is transferred to a heating substrate using a transfer rod; the temperature of the heating substrate is 450 - 800 °C, preferably 550 °C; the holding time for the in-situ corrosion of the liquid lead-bismuth is 2 - 300 min.

[0025] Furthermore, the characterization and analysis in step S3 include: analyzing the macroscopic surface morphology, diffusion layer thickness, element migration, and phase change after corrosion of the composite film material sample.

[0026] Furthermore, after the corrosion of different materials using the sandwich structure, the surface morphologies are different, so the indexes for judging their characterization results are also different and need to be designed according to the actual situation. For example, in some specific embodiments of the present application, through electron microscopy, EDS elemental energy spectrum analysis, etc. of the sample surface and cross-section, the flatness of the sample surface and the element distribution are observed, and then the corrosion degree and the corrosion resistance of the target component film are judged. Generally speaking, the material corresponding to the component of the sample with higher surface flatness and higher density of the corrosion oxidation product after corrosion is selected.

[0027] The third technical solution of the present invention provides an application of a screening method for liquid lead-bismuth corrosion-resistant materials based on a sandwich structure. This method is used to screen corrosion-resistant materials and uses corrosion characteristics to guide and design the improvement of high-performance corrosion-resistant materials; the high-performance corrosion-resistant materials are used in the field of extreme working environments, such as as a corrosion-resistant coating for the structural materials of the lead-cooled fast reactor of the fourth-generation nuclear reactor.

[0028] Furthermore, by depositing a target component film sample and a lead-bismuth alloy film (lead-bismuth alloy dielectric layer) on a single crystal silicon wafer in the present invention, it is possible to avoid the influence of the large adsorption energy of the smooth surface of the magnetron sputtered deposited film on the corrosion conditions due to the adsorption of more oxygen atoms. The one-piece forming and in-situ corrosion test method can not only avoid the interference of the oxygen atoms adsorbed on the film surface, but also adjust the gas flow rate during the deposition process of each layer through the vacuum system in the magnetron sputtering system, so as to control the oxygen content, and realize sputtering and corrosion under ultra-low oxygen concentration conveniently and efficiently. Because the magnetron sputtering process has good film quality, good uniformity, and fast deposition speed, the sputtered liquid lead-bismuth dielectric layer is cleaner and denser in contact with the sample than in the traditional corrosion test, and can better explore the interfacial corrosion behavior between the liquid lead-bismuth and the material. Therefore, based on the existing equipment, the present invention can quickly explore the corrosion behavior between the target material and the liquid lead-bismuth interface at appropriate corrosion temperatures and oxygen concentrations. The present invention has no special requirements on how to obtain the sample to be tested for corrosion resistance and whether the sample needs to be transferred. Based on the premise of obtaining a sample deposited with a liquid lead-bismuth dielectric layer, those skilled in the art can implement the technical solution of the present application.

[0029] According to the above technical solution, the present invention has at least the following beneficial effects and advantages:

[0030] (1) The present invention provides a rapid corrosion method based on a sandwich structure. By adjusting the magnetron sputtering process parameters, a composite thin film material deposited with a liquid lead-bismuth dielectric layer can be rapidly, controllably, and efficiently prepared. Further, through in-situ liquid lead-bismuth corrosion testing, the surface and cross-section of the sample after corrosion are observed and analyzed to explore the corrosion behavior between the material and the liquid lead-bismuth interface. This corrosion method is efficient and simple, realizing the integral molding of the sample and the corrosion layer and in-situ high-vacuum ultra-low oxygen corrosion.

[0031] (2) The present invention is a new corrosion testing method proposed to solve the problems existing in existing nuclear structure materials. In the test content surrounding liquid lead-bismuth corrosion, the design and testing of traditional corrosion tests usually have a long exploration period. The present invention can prepare a uniform and dense liquid lead-bismuth dielectric layer by magnetron sputtering to achieve rapid and in-situ corrosion.

[0032] (3) The present invention applies the magnetron sputtering preparation process, which can control the oxygen content during the deposition process of the sample thin film and the liquid lead-bismuth dielectric layer, thereby ensuring the oxygen concentration during the corrosion process and laying a foundation for the research on liquid metal interface corrosion. Taking the corrosion of lead-bismuth eutectic alloy as an example provides theoretical and methodological inspiration for the research and development of other corrosion tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the deposition sample process and corrosion experiment in the embodiment of the present invention;

[0034] Reference numerals: 1 anode, 2 substrate, 3 sample thin film, 4 liquid metal target, 5 cathode, 6 liquid metal electroatom, 7 oxygen atom, 8 argon ion;

[0035] Figure 2 It is the surface morphology characterization result of lead-bismuth alloy thin films under different sputtering parameters in Embodiment 1 of the present invention;

[0036] Reference numerals: Figure 2 (a) is a physical picture of lead-bismuth alloy thin films under different sputtering parameters, Figure 2 (b) is the surface morphology of lead-bismuth alloy thin films under different sputtering parameters;

[0037] Figure 3 It is the SEM pictures of the sample surface before and after corrosion in Embodiment 2 of the present invention;

[0038] Reference numerals: Figure 3 (a) is the surface morphology before corrosion, Figure 3 (b) is the surface morphology after corrosion;

[0039] Figure 4Schematic diagram of preparing samples by magnetron co - sputtering in Embodiment 3 of the present invention;

[0040] Reference numerals: Figure 4 (a) is a thin - film sample with a composition gradient change prepared by three - target magnetron co - sputtering, Figure 4 (b) is to divide the thin - film sample into 21 samples according to a 7×7 mm area, denoted as #1 - #21 respectively;

[0041] Figure 5 Samples, cross - section and surface morphology of the thin - film after corrosion in liquid lead - bismuth at 550℃ under high vacuum in Embodiment 3 of the present invention;

[0042] Reference numerals: Figure 5 (a) is the macroscopic surface morphology of the thin - film sample prepared in Embodiment 3 and the SEM image of the cross - section of the thin - film after corrosion; Figure 5 (b) is the surface morphology image of the sample in the yellow frame in Embodiment 3 after corrosion in liquid lead - bismuth at 550℃ under high vacuum;

[0043] Figure 6 Cross - section morphology structure and its EDS spectrum of the corrosion product of the sample in the yellow frame in Embodiment 3 of the present invention after corrosion;

[0044] Reference numerals: Figure 6 (a) is the cross - section morphology after corrosion, Figure 6 (b) is the elemental distribution of Pb, Figure 6 (c) is the elemental distribution of Bi;

[0045] Figure 7 Macroeconomic surface morphology (a) and scanning electron microscope image of surface spheroidized particles (b) after corrosion in Embodiment 4 of the present invention;

[0046] Figure 8 Scanning electron microscope images of surface spheroidized particles and surface morphology at different positions of the materials after corrosion of Samples No. 1 - 15 in Embodiment 4 of the present invention;

[0047] Figure 9 SEM image (a) and EDS spectrum (b) of the cross - section of the sample after deposition of the composite thin - film sample with a sandwich structure in Example 5 of the present invention. Detailed implementation manners

[0048] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made. These all belong to the protection scope of the present invention.

[0049] There are no particular restrictions on the sources of all raw materials of the present invention, and those purchased on the market or prepared according to conventional methods well-known to those skilled in the art are all acceptable.

[0050] The single-sided polished single-crystalline silicon wafer was purchased from Shunsheng Electronic Technology, and the crystal orientation is <111>; the single-sided polished 316 stainless steel was purchased from Changhong Metal Products, and the grade is 316.

[0051] The following examples of the present invention provide a rapid corrosion method based on a sandwich structure. In the following examples, a single-sided polished single-crystalline silicon wafer and a single-sided polished 316 stainless steel were selected as the substrate materials for preparation. Before the experiment, the substrate silicon wafer was processed into a sheet sample with a diameter of 45 mm and a size of 1×1 cm 2 and a thickness of 0.5 mm. After cleaning the silicon wafer, it was reserved for use.

[0052] Example 1 Sputtering deposition of liquid metal on a single-sided polished single-crystalline silicon wafer

[0053] As Figure 1 shown, in this example, a JGP-560b type high-vacuum magnetron sputtering system was used for material deposition and heating. The sputtering system mainly consists of the following parts: a vacuum chamber, a vacuum pump group, a magnetron sputtering target, a magnetic field system, a substrate stage, a gas control system, a power supply system, and a monitoring system. Through a high-vacuum environment, magnetic field enhancement, and precise control, efficient and high-quality thin film deposition can be achieved. For more specific experimental operation steps and precautions for instrument use, reference can be made to the instruction manual of the JGP-560b type high-vacuum magnetron sputtering system.

[0054] The specific steps of the experiment are as follows:

[0055] As Figure 1 shown in the left figure, the single-sided polished single-crystalline silicon wafer (i.e., sample film 1 in the figure) was fixed on the substrate 2. When the vacuum degree of the magnetron sputtering chamber reached 1.5×10 -3 Pa, a certain amount of argon gas (i.e., the excited argon ions 8 represented by the green spheres in the figure) was introduced. Keeping the sputtering pressure, the power of the lead-bismuth alloy target (i.e., the liquid metal target 4 in the figure, and the purple spheres represent the sputtered liquid metal electrons 6 and deposited on the sample film 1) was adjusted to 15-90 W. After pre-sputtering for 5 min to clean the target, then sputtering film deposition was carried out for 5 min. After the sputtering ended, the sample was taken out after the cavity naturally cooled to room temperature for 30 min, and a lead-bismuth alloy film was obtained. As Figure 2 shown, if the liquid metal target is replaced for multiple sputtering depositions, a metal film with a sandwich structure as Figure 1 shown in the right figure can be obtained.

[0056] Figure 2Among them, the LBE target was placed on the RF power supply to sputter samples No. 1-1 to 1-3, and on the DC power supply to sputter samples No. 2-1 to 2-5. The specific preparation parameters are shown in Table 1.

[0057] Table 1 Preparation of sandwich thin film structures with different magnetron sputtering parameters

[0058]

[0059] Through Figure 2 From the SEM surface morphology diagram of the thin film sample, it can be seen that when the lead-bismuth alloy target is placed at the DC power supply target position, when the sputtering power increases to 40 W (i.e., sample 2-4), nano-scale deposition particles appear on the surface of the alloy thin film, and at this time the flatness of the sample surface begins to decrease. When the sputtering power is the same (comparing sample 1-1 and sample 2-5), the thin film obtained by RF sputtering has worse surface density and flatness than the thin film obtained by DC sputtering.

[0060] In view of the fact that the flatness and density of the lead-bismuth alloy thin film surface will affect the atomic diffusion process in the subsequent corrosion test, in order to ensure that the thin film material with higher surface flatness and better density can be used in the subsequent embodiments, when preparing the composite thin film for corrosion test, the present application selects a DC power supply to sputter the lead-bismuth alloy target, and the sputtering power needs to be controlled below 40 W.

[0061] Example 2 Liquid metal corrosion experiment on single-sided polished 316 stainless steel

[0062] (1) Sample preparation

[0063] Based on the conditions in Table 1 and the corresponding Figure 2 (b) results, in this example, the experimental parameters (sputtering pressure 1 Pa, power 30 W, surface smooth and flat) selected when preparing sample 2-3 in Example 1 are chosen. Use a diamond pen to scratch and mark the position on the stainless steel surface, and deposit a lead-bismuth alloy thin film on the clean 316 stainless steel thin sheet with a polished surface to obtain a 316 stainless steel thin sheet deposited with a lead-bismuth alloy thin film. Observe the oxide morphology on the sample surface through a scanning electron microscope (SEM) in secondary electron mode, as shown in Figure 3 (a).

[0064] The purpose of scratching and marking the position with a diamond pen is for positioning to ensure that the positions for comparison before and after are consistent, and to exclude the differences brought by different material conditions due to different sample positions.

[0065] (2) In-situ heating corrosion

[0066] After sputtering, heat the 316 stainless steel thin sheet sample deposited with a lead-bismuth alloy thin film in the chamber to 450 °C, hold for 5 min, and take out the specimen after cooling to room temperature with the chamber.

[0067] The thin film sample after in-situ heating corrosion was immersed in a cleaning solution of ethanol, acetic acid, and 30% hydrogen peroxide (volume ratio 1:1:1), and repeatedly washed until no bubbles were generated in the cleaning solution, that is, the sample was cleaned. The surface oxide morphology of the sample was observed by a scanning electron microscope (SEM) in the secondary electron mode, as shown in Figure 3 (b).

[0068] Figure 3 (a) is the surface morphology of the stainless steel thin sheet before corrosion at the marked position, Figure 3 (b) is the surface morphology of the stainless steel thin sheet after corrosion of the deposited lead-bismuth alloy thin film. It can be seen from the figure that discontinuous micron-sized oxide particles are formed on the surface of the stainless steel after corrosion, showing experimental results and corrosion products similar to those of the traditional lead-bismuth alloy immersion method corrosion experiment. It is confirmed that the lead-bismuth alloy thin film is effective and efficient in the corrosion experiment.

[0069] Example 3 Lead-bismuth corrosion experiment based on the sandwich structure

[0070] (1) Sputtering preparation of alloy thin film (single-layer target component thin film)

[0071] As Figure 4 (a) shows, in this example, a single-sided polished single-crystalline silicon wafer was selected as the substrate, and a high-entropy amorphous thin film prepared by three-target co-sputtering was used as the material to be measured. In this sputtering scheme, a mask plate was covered on the silicon wafer. When the vacuum degree of the magnetron sputtering chamber reached 1.5×10 -3 Pa, 40 sccm of argon gas was introduced, the sputtering pressure was maintained at 1 Pa, the power of the FeTaB composite alloy target was adjusted to 140 W, the power of the Ti elemental target was set at 70 W, and the power of the W elemental target was set at 60 W. The target was pre-sputtered for 5 min to clean the target, and then the substrate was kept stationary for 10 min for sputtering thin film deposition. After sputtering, due to different sputtering ranges from the target to various positions on the substrate, the sputtering rates corresponding to different positions were different, and an alloy thin film with a composition gradient change was obtained. The sample was transferred to the upper part of the lead-bismuth eutectic alloy target using a transfer rod. The samples prepared according to the above preparation scheme could be divided into 21 regions ( Figure 4 (b)), each region being 7 mm×7 mm, for subsequent exploration of the corrosion behavior of different element contents in the liquid lead-bismuth alloy.

[0072] (2) Sputtering preparation of the lead-bismuth eutectic alloy corrosion layer

[0073] The argon gas flow rate was changed to 60 sccm, the sputtering pressure was maintained at 1 Pa, and the power of the lead-bismuth eutectic alloy target was adjusted to 30 W. The target was pre-sputtered for 5 min to clean the target, and then 10 min of sputtering thin film deposition was carried out. After sputtering, the sample was transferred to co-sputtering using a transfer rod.

[0074] (3) Sputtering preparation of the third layer of target component thin film

[0075] The sputtering process is the same as (1). After sputtering, the sample is transferred to the heated substrate using a transfer rod.

[0076] (4) In-situ corrosion test

[0077] When the vacuum degree in the magnetron sputtering chamber drops to 8×10 -4 Pa, turn off the vacuum pump, turn on the heating power supply, set the heating temperature to 550 °C, first heat to 100 °C with 2 A, and then increase the current to 3 A as the temperature changes. When heated to 550 °C, keep it for five minutes and then turn off the heating power supply. After the substrate cools naturally to room temperature, take out the sample. As Figure 4 (a) shows, and due to the gradient sputtering of the three targets together, the surface morphologies of these 21 composite film samples are different.

[0078] (5) Characterization and analysis of the corroded samples

[0079] As Figure 5 (a) shows, island-like structures appear on the surface of the corroded sample, and the lead-bismuth alloy layers on different components show different island-like structures after corrosion. As Figure 5 (a) shows, the #5 sample has a pointed island structure, and the #16 sample has a round island structure. Further characterize the structure of the #16 sample. As Figure 5 (b) shows, a uniformly distributed round island structure can be seen.

[0080] As Figure 6 The SEM image of the surface of the #16 sample ([[]] Figure 6 a) and the EDS energy spectrum surface scan map ([[]] Figure 6 b and Figure 6 c) show that the island-like protrusions are balls formed by the liquefaction and polymerization of the lead-bismuth alloy, and there is a nanoscale oxidation structure on the surface. In addition, the overall clarity of this EDS energy spectrum surface scan map is good, and the background noise is low, which can more accurately reflect the element distribution on the sample surface. Combining the above characterization results of the pictures, it can be seen that: through the magnetron sputtering method, the present invention prepares a composite film material deposited with a lead-bismuth alloy corrosion layer (the target component film is an alloy film). After in-situ low-oxygen liquid lead-bismuth alloy corrosion of the composite film material, different corrosion behaviors of each element during the corrosion process can be obtained by observing the surface and cross-section. Through the method provided by the present invention, the corrosion mechanism of alloy film materials in lead-bismuth alloy can be prepared and tested with high quality and quickly, which has important application prospects.

[0081] Example 4 explores the influence of the corrosion environment on the corrosion results

[0082] The difference between Example 4 and Example 3 is to adjust the chamber pressure during the corrosion process. A small amount of argon is introduced during the heating process to keep the ambient pressure at about 20 Pa. The corrosion results are asFigure 7 As shown, tiny spherical protrusions appeared on the surface of Sample #8 after heating. From Figure 7 the SEM image in (b), it can be seen that the diameter of the spheroidized lead-bismuth alloy is about 50 microns, and there are dense fine products on the sample surface.

[0083] Furthermore, samples No. 1 to 15 in the thin film sample group (as Figure 7 shown in (a)) were characterized. Figure 8 The SEM images of the spheroidized particles and surface morphologies at different positions on the surface of the material after corrosion in Example 4 are shown. From Figure 8 it can be seen that the diameter of the micron-scale spheroidized particles formed on the surface of the thin film sample after corrosion changes with the gradient change of the content of the component elements (the gradient is as Figure 4 shown in b), but there is no obvious difference in the dense products under the particles.

[0084] Comparing with Example 3, it can be seen that by changing the base pressure in the chamber during the corrosion test, there are obvious differences in the morphology of the lead-bismuth alloy on the surface of the thin film sample after corrosion. It shows that in this rapid corrosion experimental method, the surface kinetics of the liquid lead-bismuth medium layer has a great influence on the corrosion morphology. By adjusting the corrosion environment and the composite film structure, different surface protrusion morphologies can be obtained. This special formation situation is coordinated with the corrosion resistance performance. Perhaps this inventive method can also screen alloy components with excellent properties.

[0085] Example 5 Thickness Characterization of a Composite Film Material with a Sandwich Structure

[0086] In order to characterize the structure of the composite film material with a sandwich structure used for the lead-bismuth alloy corrosion test, in this example, the composite film material with a sandwich structure obtained by sputtering was subjected to interface characterization. The specific steps include:

[0087] (1) Sputtering Preparation of the Composite Film Material with a Sandwich Structure

[0088] The difference between Example 5 and Example 3 is that a composite target with an atomic ratio of Fe 34.5 Ta 9.8 B 14.1 Ti 11.1 W 30.5 was used for sputtering the amorphous alloy layers of the first and third layers.

[0089] (2) Composite Structure Characterization

[0090] Figure 9 Figure (a) is the SEM image of the cross-section of the composite film sample with a sandwich structure after deposition, and Figure 9 Figure (b) is the EDS spectrum ([[]] Figure 9 ). As Figure 9As shown, in this embodiment, a composite film with a sandwich structure for corrosion testing was successfully prepared by the magnetron sputtering method in (1). The composite film has three layers, where the alloy layers of the first and third layers have a thickness of approximately 1.25 μm, and the thickness of the middle lead-bismuth layer is approximately 500 nm. In summary, the embodiment provided by the present invention successfully prepared a composite film with a sandwich structure for corrosion testing.

[0091] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention as disclosed should be within the protection scope of the present invention.

Claims

1. A composite film material with a sandwich structure, characterized in that, The sandwich structure includes two outer layers and an intermediate interlayer. Both outer layers are target component films, and the intermediate interlayer is a lead-bismuth alloy film; the film thickness of each layer is 0.5 - 2 μm.

2. A screening method for a material resistant to liquid lead-bismuth corrosion, characterized in that, Based on the composite thin film material with a sandwich structure described in claim 1, it includes the following steps: S1. Prepare a sample of the composite thin film material with a sandwich structure as described in claim 1; S2. Transfer the composite thin film material sample obtained in step S1 to a heated substrate, and the lead-bismuth alloy film in the intermediate interlayer performs in-situ corrosion of the target component films of the two outer layers with liquid lead-bismuth; S3. Conduct characterization and analysis on the composite thin film material sample after in-situ corrosion, and judge the liquid lead-bismuth corrosion resistance of the target components in the composite thin film material sample according to the characterization results.

3. The screening method of the liquid lead-bismuth corrosion-resistant material according to claim 2, wherein The preparation of the composite thin film material sample with a sandwich structure described in step S1 is carried out in a magnetron sputtering device; The preparation process is as follows: First, prepare a single-layer target component film sample; deposit a layer of lead-bismuth alloy film on the single-layer target component film sample to obtain a target component film / lead-bismuth alloy film sample; deposit a layer of target component film sample on the target component film / lead-bismuth alloy film sample to obtain a sandwich structure of target component film / lead-bismuth alloy film / target component film, which is the composite thin film material sample with a sandwich structure.

4. The screening method of the liquid lead-bismuth corrosion-resistant material according to claim 3, characterized in that, When preparing the composite film material sample with a sandwich structure in step S1, the substrate of the magnetron sputtering device rotates at a rotation speed of 5-10 r / min; the purity of the target used in the magnetron sputtering is greater than 99.95%; the magnetron sputtering is carried out in an inert gas atmosphere, and the gas flow rate of the inert gas atmosphere is in the range of 40-60 sccm; the working pressure of the magnetron sputtering is 0.5-1.5 Pa, the sputtering power is 30-130 W, and the sputtering time is 1-15 min; the distance between the target used in the magnetron sputtering and the substrate of the magnetron sputtering device is 4-8 cm; in the chamber of the magnetron sputtering device, the base pressure is regulated to below 1.5×10 -3 Pa by a molecular pump, and 40-60 sccm of pure argon gas and 0-30 sccm of a mixed gas of argon and oxygen are introduced, and the oxygen content is controlled by the ratio of the pure argon gas and the mixed gas of argon and oxygen.

5. The screening method of the liquid lead-bismuth corrosion-resistant material according to claim 3, characterized in that The method for preparing a single-layer target component thin film sample described in step S1 is as follows: Any one of a single-crystalline silicon wafer or a stainless-steel sheet is used as a substrate, and the sputtering conditions of the target component material target are controlled as follows: the argon gas flow rate is 30 to 60 sccm, the base pressure is 1.5×10 -3 ~9.0×10 - 4 Pa, the sputtering gas pressure is 1.0 to 1.4 Pa, and the target power is 30 to 150 W.

6. The screening method of the liquid lead-bismuth corrosion-resistant material according to claim 3, characterized in that, The method of depositing a layer of lead-bismuth alloy film on the single-layer target component film sample described in step S1 is: lower the sputtering chamber to the target vacuum degree, control the gas flow rate during sputtering, so as to control the oxygen concentration in the deposited lead-bismuth alloy, and deposit a layer of lead-bismuth alloy film on the surface of the film sample; the lead-bismuth alloy is sputtered by a liquid lead-bismuth target, and the liquid lead-bismuth target is a lead-bismuth eutectic alloy target; The conditions for sputter-depositing another layer of target component film sample on the target component film / lead-bismuth alloy film are the same as those for preparing the single-layer target component film sample.

7. The screening method of the liquid lead-bismuth corrosion-resistant material according to claim 2, characterized in that The method for performing liquid lead-bismuth in-situ corrosion test on the prepared composite thin film material sample in step S2 is: First, transfer the composite thin film material sample to a heated substrate, introduce an inert gas, and then preheat the heated substrate of the magnetron sputtering device to the temperature required for in-situ corrosion. After corroding for a certain time, transfer and take out the substrate.

8. The screening method of the liquid lead-bismuth corrosion-resistant material according to claim 7, wherein When performing the liquid lead-bismuth alloy in-situ corrosion test, use a transfer rod to transfer the thin film material sample to the heated substrate; the temperature of the heated substrate is 450 - 800 °C; the holding time for the liquid lead-bismuth in-situ corrosion is 2 - 300 min.

9. The screening method of the liquid lead-bismuth corrosion-resistant material according to claim 2, characterized in that The characterization and analysis described in step S3 include: analyzing the macroscopic surface morphology, diffusion layer thickness, element migration, and phase change after corrosion of the composite thin film material sample; the judgment indexes of the analysis results include the morphology and size of the corrosion products on the sample surface, the density of the corrosion products, and the element diffusion situation.

10. Use of a screening method for a material resistant to liquid lead-bismuth corrosion according to claim 2, characterized in that, The application includes: being used for screening corrosion-resistant materials; the corrosion-resistant materials are used in extreme working environments, and the extreme working environments include: being used as a corrosion-resistant coating for the structural materials of the lead-cooled fast reactor of the fourth-generation nuclear reactor.

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