Electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates

Abstract

The invention relates to the technical field of rhenium materials, in particular to an electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates. The specific method comprises the following steps: cutting a rhenium or rhenium alloy material by adopting a linear cutting method to obtain a small sample with a proper size, mounting, grinding and polishing, and then carrying out electrochemical corrosion. The electrolytic corrosion liquid is a mixed solution of nitric acid, hydrochloric acid and alcohol; after uniformly mixing the solution, pouring a proper amount of electrolyte into the beaker; taking a titanium plate as a cathode, and clamping the sample by iron tweezers to form an anode; turning on a power supply, setting the voltage of the constant-voltage power supply to be 8-12V, and adjusting the current to be 1.5-2.5 A; and a circuit is turned on to start corrosion, the current is kept for 20-25 s after being increased to 1-3 A, a power source is turned off, the sample is taken out, ultrasonic cleaning and blow-drying are conducted, and finally metallographic observation is conducted. The method is efficient, stable and easy to operate, a high-quality metallographic sample can be prepared, and the crystal boundary and the crystal grains in the microscopic view are clear.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation, and in particular relates to an electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates. Background Art

[0002] Rhenium is a common high-temperature refractory metal. Rhenium and its alloys have good plasticity, mechanical properties and creep resistance, and are also corrosion-resistant, wear-resistant, and high-temperature resistant. At the same time, they can maintain good strength and creep resistance under sudden temperature changes. Adding a small amount of rhenium to metals such as tungsten, molybdenum, and chromium can affect their microstructure and mechanical properties, greatly improving their high-temperature resistance. With the development of science and technology, rhenium has received more and more attention in modern technology, scientific research, production and other fields, including electronic technology, high-temperature alloys, rhenium catalysts, etc. Rhenium high-temperature alloys can be used in the combustion chambers, turbine blades, exhaust nozzles, jet engines of aircraft and rockets, as well as the core components of thermal power generators and gas turbines. They are used as the inner wall materials of nuclear fusion reactors, atomic reactor structural materials, and space station nuclear reactor materials. They are cutting-edge technologies in the fields of aviation, aerospace, nuclear energy and military, and are widely used in modern industry. At present, rhenium products mainly include high-purity rhenium particles, rhenium sheets, rhenium bars, rhenium rods, rhenium plates, rhenium crucibles, etc. For rhenium products used in important fields, the grain size, texture, impurity distribution and macroscopic defects inside the sample are important references for evaluating rhenium indicators. The relevant metallographic corrosion method is mainly chemical corrosion, with acidic mixed solutions such as lactic acid, hydrofluoric acid, and nitric acid as corrosion components. The reaction process is slow, the surface corrosion is uneven, and the waste acid produced is difficult to handle. Summary of the invention

[0003] The invention discloses an electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates, so as to solve any of the above and other potential problems in the prior art.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: an electrochemical corrosion method for metallographic observation of rhenium or rhenium-based alloy plate, the electrochemical corrosion method specifically comprises the following steps;

[0005] S1) preparing a rhenium or rhenium-based alloy plate sample;

[0006] S2) pretreating the rhenium or rhenium-based alloy plate sample obtained in S1);

[0007] S3) Prepare electrolytic corrosion solution:

[0008] S4) The rhenium or rhenium-based alloy plate sample treated in S2) is subjected to electrochemical corrosion treatment using the electrolytic corrosion solution obtained in S3), and the corroded rhenium or rhenium-based alloy plate sample can be directly used for metallographic microscope observation.

[0009] Further, the specific steps of S4) are:

[0010] S4.1) firstly put the electrolytic corrosion solution obtained in S3) into a container, use the metal titanium plate or stainless steel plate as the cathode, use the rhenium or rhenium-based alloy plate sample treated in S2) as the anode, and turn on the power supply;

[0011] S4.2) setting the corrosion voltage and current, after turning on the circuit, observing the current value gradually increasing to the preset current value, maintaining it for a period of time and then turning off the power supply; taking out the rhenium or rhenium-based alloy plate sample;

[0012] S4.3) Rinse the residual corrosive liquid on the surface with deionized water, use ultrasonic cleaning to remove impurities, rinse with alcohol and blow dry, and then it can be directly used for metallographic microscope observation.

[0013] Furthermore, the liquid level of the corrosive liquid in said S4.1) does not exceed 2 / 3 of the container.

[0014] Further, the corrosion voltage in S4.2) is 8-12V, and the current is adjusted to 1.5-2.5A;

[0015] The preset current value is 2.0-3.0A and the holding time is 20-25s.

[0016] Furthermore, the rhenium or rhenium-based alloy plate sample in S1) is cut by wire cutting.

[0017] Further, the pretreatment process in S2) is:

[0018] S2.1) performing inlay treatment on the rhenium or rhenium-based alloy plate sample obtained in S1);

[0019] S2.2) First, grind and polish the sample with 320#, 600#, 1000#, 1500#, and 2000# in sequence for 2-3 minutes, and then polish it with W3 or W1 polishing liquid on the damping polishing cloth for 5-10 minutes.

[0020] Furthermore, the embedding in S2.1) is performed by hot embedding of conductive embedding materials.

[0021] Further, the specific process in S3) is:

[0022] A certain amount of nitric acid, hydrochloric acid and alcohol are mixed and stirred evenly to obtain an electrolytic corrosion solution; wherein the nitric acid accounts for 2%-10% of the total volume, and the hydrochloric acid accounts for 3% of the total volume.

[0023] A metallographic observation sample of rhenium and rhenium-based alloy plates is prepared by adopting the electrochemical corrosion method.

[0024] The beneficial effects of the present invention are as follows: due to the adoption of the above technical solution, the electrochemical corrosion method of the present invention has simple operation, significant effect, can prepare high-quality metallographic samples, the collected metallographic pictures have clear microscopic morphology, and the sample surface information is complete. The method can effectively remove the uneven scratches and stress layers on the sample surface, the sample surface has clear grain boundaries, obvious grain arrangement, and high resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a flowchart of an electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates.

[0026] Figure 2 The electrochemical corrosion metallographic image of rhenium particles prepared by the electrochemical corrosion method of the present invention is shown.

[0027] Figure 3 The electrochemical corrosion metallographic image of the rhenium sheet prepared by the electrochemical corrosion method of the present invention is shown. DETAILED DESCRIPTION

[0028] like Figure 1 As shown, the present invention provides an electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates, the method comprising the following steps:

[0029] According to the requirements, the rhenium plate or rhenium grain is cut into samples of suitable size by wire cutting, with a length and width not exceeding 8mm and a height of about 3mm;

[0030] The cut samples are mounted and then polished to remove surface scratches;

[0031] Preparation of electrolytic corrosion solution:

[0032] Prepared as electrolytic corrosion solution for standby use;

[0033] After the samples were mounted, they were ground and polished, and then the surface impurities were cleaned with ultrasonic deionized water, rinsed with alcohol and dried;

[0034] Electrochemical corrosion treatment:

[0035] Pour an appropriate amount of corrosion liquid into a 500mL beaker, the liquid level should not exceed 2 / 3 of the beaker, use a metal titanium plate or stainless steel plate as the cathode, and connect it to the negative pole of the DC power supply; use iron tweezers or other metal tweezers to clamp the sample to form an anode, and connect it to the positive pole of the power supply; turn on the power, set the corrosion voltage to 8-12V, and adjust the current to 1.5-2.5A; after turning on the circuit, observe that the current value gradually increases to 2.0-3.0A and does not change, keep it for 20-25s and then turn off the power; take out the sample, rinse the residual corrosion liquid on the surface with deionized water, use ultrasonic cleaning to remove impurity particles, rinse with alcohol and blow dry.

[0036] As the preferred technical solution:

[0037] In step 2), the embedding method is a hot embedding process of conductive embedding materials, and the circuit is connected by clamping with metal tweezers. The hot embedding process can complete the circuit conduction without removing the sample.

[0038] In step 2), 320#, 600#, 1000#, 1500#, and 2000# are selected in sequence to grind and polish the sample, and then polish it on the polishing cloth with W3 or W1 polishing liquid, which can effectively reduce scratches on the sample surface.

[0039] The rhenium sample electrochemically corroded by the method of the present invention can be used for metallographic observation, electron scanning microscope (SEM), energy spectrum (EDS) and other microscopic analysis, and has high quality.

[0040] Example 1

[0041] An electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates, the specific method comprising the following steps:

[0042] The rhenium particles prepared by sintering are cut, ground and polished.

[0043] Use wire cutting to cut samples of suitable size from the rhenium particles, with a length, width and height of 8mm*6mm*3mm. Then use an automatic sample mounter for hot mounting. After cooling and solidification, take it out for mechanical grinding and polishing. Use 320#, 600#, 1000#, 1500#, and 2000# to polish the samples in turn to remove surface and large-sized scratches. In view of the hard geological conditions of the rhenium particle samples, the mechanical polishing stage uses a hard polishing cloth with W3 and W1 polishing liquids to effectively reduce finer scratches on the sample surface. After grinding and polishing, the sample is ultrasonically cleaned to remove the polishing liquid and impurities attached to the surface, and then cleaned with alcohol and blown dry.

[0044] Electrochemical corrosion treatment:

[0045] Pour an appropriate amount of corrosion liquid into a 500mL beaker, with the liquid level not exceeding 2 / 3 of the beaker. Use a metal titanium plate or stainless steel plate as the cathode and connect it to the negative pole of a DC power supply. Use iron tweezers or other metal tweezers to clamp the sample to form an anode and connect it to the positive pole of the power supply. Turn on the power supply, set the corrosion voltage to 8V, and adjust the current to 1.5A. After turning on the circuit, observe that the current value gradually increases to 2.0A and does not change. Keep it for 20s and then turn off the power. Take out the sample, rinse the residual corrosion liquid on the surface with deionized water, use ultrasonic cleaning to remove impurities, rinse with alcohol and blow dry.

[0046] The rhenium particle sample was observed under an optical microscope to obtain the metallographic diagram of the sample, as shown in Figure 2 shown.

[0047] Example 2

[0048] An electrochemical corrosion method for metallographic observation of rhenium and rhenium-based alloy plates, the specific method comprising the following steps:

[0049] The rhenium sheets prepared by rolling processing are cut, ground and polished.

[0050] The wire cutting technology is used to cut a sample of suitable size from the rhenium sheet, with a length and width of 8mm*6mm. Then, it is hot-mounted using an automatic sample mounter. After cooling and solidification, it is taken out for mechanical grinding and polishing. 320#, 600#, 1000#, 1500#, and 2000# are used to polish the sample in turn to remove surface and large-sized scratches. The mechanical polishing stage is carried out on a hard material polishing cloth with W3 and W1 polishing liquid, which can effectively reduce finer scratches on the sample surface. After grinding and polishing, the sample is ultrasonically cleaned to remove the polishing liquid and impurities attached to the surface, and then cleaned with alcohol and blown dry.

[0051] Electrochemical corrosion treatment

[0052] Pour an appropriate amount of corrosion liquid into a 500mL beaker, with the liquid level not exceeding 2 / 3 of the beaker. Use a metal titanium plate or stainless steel plate as the cathode and connect it to the negative pole of a DC power supply. Use iron tweezers or other metal tweezers to clamp the sample to form an anode and connect it to the positive pole of the power supply. Turn on the power, set the corrosion voltage to 12V, and adjust the current to 2.5A. After the circuit is turned on, observe that the current value gradually increases to 3.0A and does not change. Keep it for 25s and then turn off the power. Take out the sample, rinse the residual corrosion liquid on the surface with deionized water, use ultrasonic cleaning to remove impurities, rinse with alcohol and blow dry.

[0053] The metallographic image of the rhenium sheet sample was obtained by optical microscope observation. Figure 3 shown.

[0054] The above examples are only for illustrating the technical features and concepts of the present invention, and are intended to enable people familiar with the technology to understand the content of the present invention and implement it, and cannot be used to limit the scope of protection of the present invention. Any equivalent changes and modifications made based on the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electrochemical corrosion method for metallographic observation of rhenium or rhenium-based alloy plates, characterized in that: The electrochemical corrosion method specifically comprises the following steps: S1) preparing a rhenium or rhenium-based alloy plate sample; S2) pretreating the rhenium or rhenium-based alloy plate sample obtained in S1); S3) Prepare electrolytic corrosion solution: S4) The rhenium or rhenium-based alloy plate sample treated in S2) is subjected to electrochemical corrosion treatment using the electrolytic corrosion solution obtained in S3), and the corroded rhenium or rhenium-based alloy plate sample can be directly used for metallographic microscope observation.

2. The electrochemical corrosion method according to claim 1, characterized in that: The specific steps of S4) are: S4.1) firstly put the electrolytic corrosion solution obtained in S3) into a container, use the metal titanium plate or stainless steel plate as the cathode, use the rhenium or rhenium-based alloy plate sample treated in S2) as the anode, and turn on the power supply; S4.2) setting the corrosion voltage and current, after turning on the circuit, observing the current value gradually increasing to the preset current value, maintaining it for a period of time and then turning off the power supply; taking out the rhenium or rhenium-based alloy plate sample; S4.3) Rinse the residual corrosive liquid on the surface with deionized water, use ultrasonic cleaning to remove impurities, rinse with alcohol and blow dry, and then it can be directly used for metallographic microscope observation.

3. The electrochemical corrosion method according to claim 2, characterized in that: The liquid level of the corrosive liquid in S4.1) does not exceed 2 / 3 of the container.

4. The electrochemical corrosion method according to claim 2, characterized in that: The corrosion voltage in S4.2) is 8-12V, and the current is adjusted to 1.5-2.5A; The preset current value is 2.0-3.0A and the holding time is 20-25s.

5. The electrochemical corrosion method according to claim 1, characterized in that: The rhenium or rhenium-based alloy plate sample in S1) is cut by wire cutting.

6. The electrochemical corrosion method according to claim 1, characterized in that: The pretreatment process in S2) is: S2.1) performing inlay treatment on the rhenium or rhenium-based alloy plate sample obtained in S1); S2.2) First, grind and polish the sample with 320#, 600#, 1000#, 1500#, and 2000# in sequence for 2-3 minutes, and then polish it with W3 or W1 polishing liquid on the damping polishing cloth for 5-10 minutes.

7. The electrochemical corrosion method according to claim 1, characterized in that: The embedding in S2.1) is performed by hot embedding of conductive materials.

8. The electrochemical corrosion method according to claim 1, characterized in that: The specific process in S3) is: A certain amount of nitric acid, hydrochloric acid and alcohol are mixed and stirred evenly to obtain an electrolytic corrosion solution; wherein the nitric acid accounts for 2%-10% of the total volume, and the hydrochloric acid accounts for 3% of the total volume.

9. A metallographic observation sample of rhenium and rhenium-based alloy plate, characterized in that: The rhenium and rhenium-based alloy plate metallographic observation samples are prepared by the electrochemical corrosion method described in any one of claims 1 to 8.

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