Preparation method of high-quality surface pure rhenium sample

Abstract

The invention discloses a preparation method of a high-quality surface pure rhenium sample, which comprises the following steps of: cutting and sampling a pure rhenium original material, grinding, polishing and cleaning by ultrasonic vibration, loading the sample on a sample clamping device, then putting the sample into a mixed solution, refrigerating and carrying out electrolytic polishing treatment to obtain the high-quality surface pure rhenium sample. And a pure rhenium sample with a high-quality surface can be obtained. According to the method, the defects of an existing high-quality surface pure rhenium sample preparation method are overcome, single or multiple samples can be prepared at the same time through the method, the quality effect is excellent, the rhenium crystal information analysis rate reaches 99% or above, the urgent requirement of the academic circle for the high-quality surface pure rhenium sample is met, and the method is suitable for popularization and application. And a good technical support and a material preparation basis are provided for macroscopic performance analysis of pure rhenium and deep research work of microscopic deformation mechanism. The method has the advantages of being simple, convenient, efficient, high in safety, low in cost, excellent in technical effect and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of material preparation and surface treatment, and particularly provides a method for preparing a high-quality surface pure rhenium sample. Background Art

[0002] Rhenium (Re) is a silver-white rare refractory metal located in Group VIIB of the periodic table. Due to its high strength, good plasticity, excellent creep resistance, and excellent high-temperature resistance, corrosion resistance, and heat shock resistance, it is widely used in high-temperature alloys, aerospace, electronic engineering, petrochemical, biomedical and other fields, and has become one of the important new materials in modern high-tech fields. Generally speaking, the main preparation processes of pure rhenium include powder metallurgy, chemical vapor deposition, electro-deposition, etc. Among them, chemical vapor deposition and electro-deposition are mostly used to deposit rhenium coatings and transition layers, and to prepare thin-walled rhenium tubes. Rhenium wires, rhenium grains and rhenium sheets that have reached the application state are prepared by powder metallurgy processes such as ball milling, isostatic pressing, sintering and multiple cold rolling forming processes.

[0003] Pure rhenium crystals have a close-packed hexagonal (HCP) structure. During the processing of rhenium products, different processing methods are required, such as rolling deformation, heat treatment, etc., which will lead to the formation of differences in grain size, preferred orientation, etc. These factors will affect the activation of crystal slip systems and the formation of twins during subsequent deformation, processing or service, and thus affect the properties of the material. When rhenium components are applied to ultra-heat-resistant and sub-heat-resistant components of rockets, various space return capsules, satellite attitude control engines, etc. in the aerospace field, they will be affected by harsh environments such as high temperature, corrosion, oxidation, creep, and irradiation. The microstructure, structure, texture, and micro-defects of rhenium crystals will further evolve, thus affecting the application of pure rhenium components. When studying these materials, techniques such as metallography, XRD, EBSD, and TEM are needed for analysis. Due to the high hardness and high wear resistance of pure rhenium, problems such as the easy generation of deformation layers on the surface during sample preparation, residual scratches on the surface after polishing and corrosion, and the inability to analyze crystal information are likely to occur. Therefore, pure rhenium samples with high-quality surfaces are urgently needed for studying the deep deformation mechanism, property anisotropy, in-situ tests, etc. of rhenium components. Scholars are also looking for an effective method for preparing pure rhenium samples with high-quality surfaces.

[0004] Due to the scarcity and special uses of rhenium, there are few relevant literatures and patents on the research, development and application of rhenium in various countries. The methods applied to the preparation of pure rhenium samples are very few and have certain limitations. For example, the researcher Julian E. C. Sabisch proposed in the article "Microstructural evolution of rhenium Part I: Compression. Materials Science and Engineering: A, 2018, 732: 251-258." to use 5% 2-butoxyethanol, 35% perchloric acid and nitric acid solution with a volume ratio of 2:1, and 60% methanol and ethanol solution with a volume ratio of 1:1 as the electrolytic polishing solution. This electrolytic polishing solution has a complex composition and contains a strongly oxidizing and corrosive nitric acid solution, which is not conducive to safe operation; for the invention patent with the application number 202110175782.2, a method for preparing a chemical vapor deposition rhenium EBSD sample is provided. The sample preparation process of this method is complex, requires thermal inlaying of the sample, and has a long polishing time. The metallographic pictures shown have obvious scratches, which will affect subsequent research such as slip system observation, EBSD analysis, and XRD stress analysis.

[0005] Therefore, it is extremely important to provide a preparation method for high-quality surface pure rhenium samples that is simple, efficient, highly safe, low-cost and has excellent technical effects. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology and the urgent needs of the academic community, the present invention provides a preparation method for high-quality surface pure rhenium samples with simple process, high safety, easy operation, low cost and excellent technical effects. Through this method, single and multiple samples can be prepared and processed simultaneously, effectively removing the grinding and polishing marks on the sample surface. The grain boundaries, slip and twin traces on the sample surface are clearly visible, and the rhenium crystal information has a very high resolution.

[0007] The technical solution of the present invention is: a preparation method for high-quality surface pure rhenium samples, and the specific preparation method includes the following steps:

[0008] S1) Cutting and sampling: Cut and sample the pure rhenium raw material according to the size of the high-quality surface pure rhenium sample to be prepared, and after grinding, polishing and ultrasonic vibration cleaning, the required sample is obtained;

[0009] S2) Electrolytic polishing: Fix the sample obtained in S1) with a clamping device, place it in an acidic electrolytic polishing solution, and perform refrigeration treatment;

[0010] S3) Connect the clamping device and the cathode plate to the positive and negative electrodes respectively, turn on the power supply. When the DC power supply voltage is adjusted to a certain value and the initial current density is adjusted to a certain value, perform electrolytic polishing treatment. When the current density rises to a certain value, turn off the power supply and clean the surface of the sample with water and anhydrous ethanol. Thus, a high-quality surface pure rhenium sample is obtained.

[0011] Further, the specific process in S1) is as follows: S1.1) Use a wire electrical discharge machining equipment to sample the pure rhenium raw material, and the X-axis, Y-axis, and Z-axis directions of the sampled pure rhenium sample correspond to the length, width, and height directions of the raw material.

[0012] S1.2) Grind the sample cut in S1.1) successively with silicon carbide sandpaper of 280# - 5000#, then perform rough polishing treatment with diamond polishing paste of W2.0 - 9.0 on a black damping polishing cloth, and subsequently perform fine polishing treatment with diamond polishing paste of W0.5 - 1.0 on a silk velvet polishing cloth.

[0013] S1.3) Place the sample ground and polished in S1.2) in a beaker, add a cleaning agent to the beaker, then place the beaker on an ultrasonic cleaner for ultrasonic vibration cleaning treatment, and subsequently dry it with anhydrous ethanol for standby.

[0014] Further, the state of the pure rhenium original sample is sintered state, deformed state or annealed state; its shape is cylindrical, plate-shaped or flaky.

[0015] Further, the treatment direction in each step of S1.2) is kept cross - perpendicular to the direction of the previous step.

[0016] The cleaning agent is acetone or anhydrous ethanol.

[0017] Further, the material of the fixed fixture in S2) is molybdenum alloy.

[0018] The electrolytic polishing solution includes 5 - 20Vol.% perchloric acid accounting for the total volume, 2 - 10Vol.% methanol accounting for the total volume, and 5 - 20Vol.% of 70 - 93Vol.% anhydrous ethanol accounting for the total volume.

[0019] The temperature of the refrigeration treatment is ≥ - 90°C.

[0020] Further, the refrigeration treatment method is using liquid nitrogen refrigeration, sub - zero low - temperature water - cooling refrigeration or thermoelectric material refrigeration.

[0021] Further, in S3), the DC power supply voltage is adjusted to 50 - 60V, and the initial current density is adjusted to 0.2 - 1.2 mA / cm 2 for electrolytic polishing treatment. When the current density rises to 6.8 - 11.5 mA / cm 2 turn off the power supply.

[0022] Furthermore, the material of the cathode plate is stainless steel, titanium alloy, zirconium alloy or molybdenum alloy.

[0023] A high-quality surface pure rhenium sample is prepared by the above preparation method.

[0024] The beneficial effects of the present invention are as follows: Due to the above technical solution, the method of the present invention makes up for the shortcomings of the existing preparation methods of high-quality surface pure rhenium samples, meets the urgent needs of the academic community for high-quality surface pure rhenium samples, provides technical support for the anisotropy of rhenium components in mechanics, corrosion and irradiation, etc., and also provides a good material preparation basis for the in-depth research work on the slip system of pure rhenium crystals, the determination of critical resolved shear stress, and microscopic defects such as dislocations and twins. This method has the advantages of simplicity, high efficiency, high safety, low cost and excellent technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the single-type sample clamping device in Example 1 using the preparation method of the present invention;

[0026] Figure 2 Metallographic microstructure diagram of the pure rhenium sample not prepared by this method;

[0027] Figure 3 SEM microstructure diagram of the pure rhenium rolled sheet sample in Example 1;

[0028] Figure 4 Schematic diagram of the multi-type sample clamping device in Example 2;

[0029] Figure 5 Phase distribution diagram of the pure rhenium thin sheet sample in Example 2;

[0030] Figure 6 Orientation distribution diagram of the pure rhenium thin sheet sample in Example 2;

[0031] Figure 7 Pole figure corresponding to the orientation of the pure rhenium thin sheet sample in Example 2;

[0032] Figure 8 SEM microstructure diagram of the pure rhenium ingot sample in Example 3;

[0033] Figure 9 SEM microstructure diagram of the deformed pure rhenium ingot sample in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0034] The technical solution of the present invention will be further described below in conjunction with specific embodiments and drawings.

[0035] A method for preparing a high-quality surface pure rhenium sample, the method comprising the following steps:

[0036] (1) Cutting and sampling: According to the size of the pure rhenium sample with a high-quality surface to be prepared, an electric discharge wire cutting device is used to sample the pure rhenium raw material, and the X-axis, Y-axis and Z-axis directions of the obtained pure rhenium sample correspond to the length, width and height directions of the raw material.

[0037] (2) Sample grinding and polishing: The pure rhenium sample cut in step (1) is successively ground on silicon carbide sandpaper with a grit size of 280# to 5000#, then coarsely polished with diamond polishing paste with a particle size of W2.0 to 9.0 on a black damping polishing cloth, and then finely polished with diamond polishing paste with a particle size of W0.5 to 1.0 on a silk velvet polishing cloth.

[0038] (3) Ultrasonic cleaning: The pure rhenium sample polished in step (2) is placed in a beaker, a cleaning agent is added to the beaker, and then the beaker is placed on an ultrasonic instrument for ultrasonic vibration cleaning treatment, and then dried with anhydrous ethanol for standby.

[0039] (4) Clamping the sample: The pure rhenium sample processed in step (3) is loaded, and it is fixed together with a specific sample clamping device. The sample clamping device can be selected according to the number and shape of the samples; the materials of the fixed clamp and the cathode plate used are beneficial to avoiding their rapid corrosion or contamination of the corrosion solution during the electrolytic polishing process of the sample, which affects the preparation of the high-quality surface pure rhenium sample.

[0040] (5) Electrolytic polishing: The pure rhenium sample clamped in step (4) and the sample clamping device are fixed in an electrolytic polishing container, and the sample clamping device and the cathode plate are respectively connected to the positive and negative electrodes of a DC power supply with wires. Then, an appropriate amount of prepared acidic electrolytic polishing solution is added to the electrolytic polishing container. After refrigeration treatment, the power supply is turned on. When the DC power supply voltage is adjusted to 50 - 60V and the initial current density is adjusted to 0.2 - 1.2 mA / cm 2 for electrolytic polishing treatment. When the current density rises to 6.8 - 11.5 mA / cm 2 , the power supply is turned off, and the sample surface is cleaned with water and anhydrous ethanol; the use of a mixed acid, refrigeration, and the regulation of electrolytic voltage and current density are beneficial to accurately controlling the corrosion rate and surface quality of the pure rhenium sample, avoiding the problem of rapid initial corrosion polishing treatment rate resulting in corrosion pits and uneven surface quality of the entire sample in the later stage.

[0041] (6) Observation and testing: The pure rhenium sample after electrolytic polishing treatment in step (5) can be used for surface quality inspection and microstructure observation under an optical microscope or a scanning electron microscope (SEM), or can be directly used for X-ray diffraction (XRD) analysis, electron backscatter diffraction (EBSD) analysis, etc. The prepared high-quality surface pure rhenium sample has directionality and representativeness.

[0042] As a preferred technical solution:

[0043] In step (1), the state of the original pure rhenium sample is sintered state, deformed state, annealed state, etc., and its shape is cylindrical, plate-shaped, flake-shaped, etc.

[0044] In step (2), the cut pure rhenium sample does not need to be cold-mounted or hot-mounted, and can be directly ground and polished, with the help of fixtures or auxiliary tools such as adhesive tape.

[0045] In step (2), the particle sizes of the sandpaper and polishing paste in each pass gradually decrease, and the grinding and polishing directions are perpendicular to the direction of the previous pass.

[0046] In step (3), the cleaning agent is acetone or absolute ethanol.

[0047] In step (4), the sample clamping device includes single-type and multi-type clamping devices. Among them, the multi-type clamping device can ensure that each sample is in the same state in the electrolyte, and the material used is molybdenum alloy with excellent stability and corrosion resistance in acidic corrosive media.

[0048] In step (5), the cathode plate material is stainless steel, titanium alloy, zirconium alloy, molybdenum alloy, etc.

[0049] In step (5), the liquid level height of the acidic electrolytic polishing solution added in the electrolytic polishing container must be greater than the height of the pure rhenium sample in the container. The electrolytic polishing solution is a mixed solution of 5 - 20Vol.% perchloric acid, 2 - 10Vol.% methanol, and 70 - 93Vol.% absolute ethanol.

[0050] In step (5), the refrigeration treatment can use liquid nitrogen refrigeration, sub-zero low-temperature water-cooled refrigeration, thermoelectric material refrigeration, etc., and the lowest refrigeration temperature is -90°C.

[0051] In step (6), defects such as surface scratches and polishing marks of the high-quality pure rhenium sample are invisible, and its EBSD resolution is excellent, with an average of over 99%.

[0052] Example 1

[0053] A method for preparing a high-quality surface pure rhenium sample for analyzing the microstructure of cold-rolled pure rhenium plates, and the specific method includes the following steps:

[0054] (1) Cutting and sampling: Use wire electrical discharge machining equipment to sample the middle part of the cold-rolled pure rhenium plate. The size of the pure rhenium sample taken is 10*8*1 mm in length, width, and height, and its X-axis, Y-axis, and Z-axis directions correspond to the rolling direction, transverse direction, and normal direction of the original material, respectively;

[0055] (2) Sample grinding and polishing: Directly grind the cuboid pure rhenium sample cut in step (1) successively on silicon carbide sandpapers of 280#, 800#, 1500#, 2000#, 3000#, and 5000# at a rotational speed of 300 revolutions per minute. Then, perform rough polishing on a black damping polishing cloth with diamond polishing paste of W9.0 and W3.0, and subsequently perform fine polishing on a silk velvet polishing cloth with diamond polishing paste of W1.0 and W0.5 at a rotational speed of 600 revolutions per minute; The grinding and polishing directions are both cross-perpendicular to the direction of the previous pass.

[0056] (3) Ultrasonic cleaning: Place the pure rhenium sample polished in step (2) in a beaker, add absolute ethanol to the beaker, then place the beaker on an ultrasonic instrument for ultrasonic vibration, and subsequently dry it with absolute ethanol for standby;

[0057] (4) Clamping the sample: Load the pure rhenium sample processed in step (3), and fix it together with a single-piece ( Figure 1 ) molybdenum alloy sample clamping device;

[0058] (5) Electropolishing: Fix the pure rhenium sample and the sample clamping device clamped in step (4) in an electropolishing container, and respectively connect the sample clamping device and the titanium alloy cathode plate to the positive and negative electrodes of a DC power supply with wires. Then, add 200 mL of a prepared acidic electropolishing solution of 10 Vol.% perchloric acid, 5 Vol.% methanol, and 85 Vol.% absolute ethanol to a 250 mL beaker, use liquid nitrogen to cool it down to -80 °C, turn on the power supply, and wait until the DC power supply voltage is adjusted to 50 V and the initial current density is adjusted to 0.4 mA / cm 2 for electropolishing treatment. When the current density rises to 8.0 mA / cm 2 , turn off the power supply and wash the sample surface with water and absolute ethanol;

[0059] (6) Observation and testing: Observe the SEM microstructure of the pure rhenium sample after electropolishing treatment in step (5). The prepared high-quality surface pure rhenium sample can overcome Figure 2 surface scratches, polishing marks and other defects shown. As Figure 3 shows, the SEM morphology of the rhenium plate sample after cold rolling deformation has no obvious visible grinding marks, and its grain size is between 2 and 200 μm.

[0060] Example 2

[0061] A method for preparing a high-quality pure rhenium sample on the surface, which is used for analyzing the orientation uniformity and texture analysis of rhenium sheets after annealing treatment. The specific method includes the following steps:

[0062] (1) Cutting and sampling: Use a wire electrical discharge machining equipment to sample the edges, middle parts, and 1 / 4 positions of the annealed pure rhenium thin sheets. The size of the obtained pure rhenium samples is 9*7*0.6 mm in length * width * height. The X-axis, Y-axis, and Z-axis directions of all samples respectively correspond to the rolling direction, transverse direction, and normal direction of the original rhenium sheet;

[0063] (2) Sample grinding and polishing: Directly grind the cuboid pure rhenium samples cut in step (1) successively on 320#, 600#, 1200#, 2000#, 3000#, and 5000# silicon carbide sandpapers, strictly control the rotation speed at 320 revolutions / min. Then, conduct rough polishing treatment with W6.0 and W2.5 diamond polishing pastes on a black damping polishing cloth. Subsequently, conduct fine polishing treatment with W1.0 and W0.5 diamond polishing pastes on a silk velvet polishing cloth, with a rotation speed of 580 revolutions / min; The grinding and polishing treatment directions are both cross-perpendicular to the direction of the previous pass.

[0064] (3) Ultrasonic cleaning: Place the pure rhenium samples polished in step (2) in a beaker, add acetone to the beaker, then place the beaker on an ultrasonic instrument for ultrasonic vibration, and then dry it with anhydrous ethanol for standby;

[0065] (4) Clamping the sample: Load the pure rhenium samples processed in step (3), and fix them together with a plurality of molybdenum alloy sample clamping devices of formula ( Figure 4 );

[0066] (5) Electropolishing: Fix the pure rhenium samples clamped in step (4) and the sample clamping device in a beaker, and respectively connect the sample clamping device and the stainless steel cathode plate to the positive and negative electrodes of a DC power supply with wires. Then, add 500 mL of a prepared acidic electropolishing solution of 15 Vol.% perchloric acid, 3 Vol.% methanol, and 82 Vol.% anhydrous ethanol to a 20*8*5 cm electropolishing container, use liquid nitrogen to cool down to -85 °C, turn on the power supply, and when the DC power supply voltage is adjusted to 60 V and the initial current density is adjusted to 0.3 mA / cm 2 for electropolishing treatment. When the current density rises to 9.5 mA / cm 2 , turn off the power supply and wash the sample surface with water and anhydrous ethanol;

[0067] (6) Observation and testing: Conduct SEM-EBSD analysis on the pure rhenium samples after electropolishing treatment in step (5). The EBSD resolution rate is 99.5%. The phase distribution map, orientation distribution map, and pole figure are respectively as shown in Figures 5 to 7As shown, the results indicate that the phase structures of the pure rhenium samples are all calibrated as HCP-Re. The preferred orientation of the samples is <0001> / / ND, which shows a bimodal basal texture on the pole figure.

[0068] Example 3

[0069] A method for preparing a high-quality surface pure rhenium sample for analyzing the micro-indentation loading deformation of electron beam melted rhenium ingots. The specific method includes the following steps:

[0070] (1) Cutting and sampling: Use a wire electrical discharge machining equipment to sample the middle position of the pure rhenium button ingot after electron beam melting treatment. The size of the pure rhenium sample taken is 10*6*1.5 mm in length * width * height. The X-axis, Y-axis, and Z-axis directions of all samples correspond to the radial, tangential, and normal directions of the original rhenium sheet respectively;

[0071] (2) Sample grinding and polishing: Directly grind the cuboid pure rhenium sample cut in step (1) successively on 180#, 400#, 1000#, 1500#, 2500#, and 5000# silicon carbide sandpapers at a rotation speed of 280 revolutions per minute. Then, conduct rough polishing treatment with W5.0 and W2.5 diamond polishing pastes on a black damping polishing cloth, and subsequently conduct fine polishing treatment with W1.0 and W0.5 diamond polishing pastes on a silk velvet polishing cloth at a rotation speed of 590 revolutions per minute. The grinding and polishing treatment directions are all cross-perpendicular to the direction of the previous pass;

[0072] (3) Ultrasonic cleaning: Place the pure rhenium sample polished in step (2) in a beaker, add acetone to the beaker, then place the beaker on an ultrasonic instrument for ultrasonic vibration, and then dry it with anhydrous ethanol for standby;

[0073] (4) Clamping the sample: Load the pure rhenium sample processed in step (3), and fix it together with a single-type molybdenum alloy sample clamping device;

[0074] (5) Electropolishing: Fix the pure rhenium sample and the sample clamping device clamped in step (4) in a beaker, and connect the sample clamping device and the zirconium alloy cathode plate to the positive and negative electrodes of a DC power supply respectively using wires. Then, add 220 mL of a prepared acidic electropolishing solution of 10 Vol.% perchloric acid, 2 Vol.% methanol, and 88 Vol.% anhydrous ethanol to a 300 mL beaker, cool it to -78 °C using liquid nitrogen, turn on the power supply, and wait until the DC power supply voltage is adjusted to 52 V and the initial current density is adjusted to 0.25 mA / cm 2 for electropolishing treatment. When the current density rises to 7.8 mA / cm 2 , turn off the power supply and wash the sample surface with water and anhydrous ethanol;

[0075] (6) Observation test: Perform a micro-indentation loading test on the pure rhenium sample after the electrolytic polishing treatment in step (5), and analyze the sample before and after the micro-indentation loading deformation with the help of an SEM electron microscope, as shown respectively in Figures 8 to 9 It can be observed from the figure that the surface quality of the rhenium ingot after electrolytic polishing is extremely good without visible grinding and polishing marks, and the interaction traces of the slip and twin systems within the grains of the deformed sample are clearly visible.

[0076] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a high-quality surface pure rhenium sample, characterized in that, The preparation method specifically includes the following steps: S1) Cutting and sampling: Cut and sample the pure rhenium raw material according to the size of the pure rhenium sample with a high-quality surface required, and after grinding, polishing and ultrasonic vibration cleaning, the required sample can be obtained; S2) Electrochemical polishing: Fix the sample obtained in S1) with a clamping device, place it in an acidic electrochemical polishing solution, and perform refrigeration treatment; S3) Connect the positive and negative electrodes, turn on the power supply. When the DC power supply voltage is adjusted to a certain value and the initial current density is adjusted to a certain value, perform electrochemical polishing treatment. When the current density rises to a certain value, turn off the power supply, and clean the surface of the sample with water and absolute ethanol. Thus, a pure rhenium sample with a high-quality surface is obtained.

2. According to the preparation method described in claim 1, the specific process in S1) is: S1.1) Use a wire electrical discharge machining equipment to sample the pure rhenium raw material, and the X-axis, Y-axis and Z-axis directions of the pure rhenium sample taken correspond to the length, width and height directions of the raw material; S1.2) Grind the sample cut in S1.1) successively with silicon carbide sandpaper of 280# - 5000#, then perform rough polishing with diamond polishing paste of W2.0 - 9.0 on a black damping polishing cloth, and then perform fine polishing with diamond polishing paste of W0.5 - 1.0 on a silk velvet polishing cloth; S1.3) Place the ground and polished sample in a beaker, add a cleaning agent to the beaker, then put the beaker on an ultrasonic instrument for ultrasonic vibration cleaning treatment, and then dry it with absolute ethanol for standby.

3. The preparation method according to claim 1, characterized in that, The state of the pure rhenium original sample is sintered state, deformed state or annealed state; its shape is cylindrical, plate-shaped or flaky.

4. The preparation method according to claim 2, characterized in that, Each treatment direction in S1.2) is kept cross-perpendicular to the direction of the previous pass; The cleaning agent is acetone or absolute ethanol.

5. The preparation method according to claim 1, wherein The material of the fixed fixture in S2) is molybdenum alloy; The electrochemical polishing solution includes 5 - 20Vol.% perchloric acid accounting for the total volume, 2 - 10Vol.% methanol accounting for the total volume, and 5 - 20Vol.% - 70 - 93Vol.% absolute ethanol accounting for the total volume; The temperature of the refrigeration treatment is ≥ - 90°C.

6. The preparation method according to claim 5, characterized in that, The refrigeration treatment method is using liquid nitrogen refrigeration, sub-zero low-temperature water-cooled machine refrigeration or thermoelectric material refrigeration.

7. The preparation method according to claim 1, characterized in that, Adjust the DC power supply voltage in S3) to 50 - 60V and the initial current density to 0.2 - 1.2 mA / cm 2 for electrolytic polishing. Wait until the current density rises to 6.8 - 11.5 mA / cm 2 and then turn off the power supply.

8. The preparation method according to claim 1, characterized in that, The material of the cathode plate in S3) is stainless steel, titanium alloy, zirconium alloy or molybdenum alloy.

9. The preparation method according to claim 1, wherein The EBSD resolution rate of the pure rhenium sample with a high-quality surface obtained by the preparation method reaches more than 99% on average.

10. A high-quality surface pure rhenium sample. It is characterized in that, The pure rhenium sample with a high-quality surface is prepared by using the preparation method described in any one of claims 1 - 9.

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