Electrochemical corrosion sample used in severe environment and preparation method thereof

Abstract

The invention relates to the field of spent fuel post-treatment corrosion electrochemistry, in particular to an electrochemical corrosion sample used in a severe environment and a preparation method of the electrochemical corrosion sample. The sample is a cylinder with one end being a hemisphere, a hole is formed in the center of the flat end face of the sample, an internal thread I is arranged in the hole, the side, where the internal thread I is located, of the sample is fastened to one end of the connecting screw through threads, and a gasket I for enhancing sealing performance is arranged at the joint of the sample and the connecting screw. The other end of the connecting screw rod is fastened with the bolt through threads, and a gasket II for enhancing the sealing performance is arranged at the joint of the connecting screw rod and the bolt; and a glass tube is sleeved outside the connecting screw rod, one end of the glass tube is tightly pressed on the gasket I, and the other end of the glass tube is tightly pressed on the gasket II. The method is suitable for preparing the electrochemical sample which needs to work in the severe environment, the electrochemical corrosion behavior of the material in the severe environment is researched, and the situation that the sample prepared by the existing electrochemical sample preparation method is damaged by the electrolyte solution can be effectively avoided.

Description

Technical Field

[0001] The invention relates to the field of spent fuel post-processing corrosion electrochemistry, in particular to an electrochemical corrosion sample used in a harsh environment and a preparation method thereof. Background Art

[0002] The typical environment of spent fuel reprocessing is characterized by high temperature, high acidity, and strong oxidation. The key equipment dissolvers and various evaporators of reprocessing have been in service for a long time under such extremely harsh conditions, and the materials will have extremely serious corrosion problems. The corrosion damage of alloys seriously threatens the safe operation of the equipment. Therefore, it is particularly important to study the corrosion behavior of equipment materials in high-temperature nitric acid media. However, the existing electrochemical corrosion sample preparation methods have some drawbacks, which lead to the destruction of electrochemical samples and affect the experimental results. We hope to develop a durable electrochemical corrosion sample that is suitable for a variety of variable working environments and is not easily damaged and used in harsh environments. This sample is put into the corrosion electrochemical experiment of key equipment materials, and the electrochemical test results are combined with other experimental results and product analysis to systematically explain the corrosion behavior of various materials in different media, provide theoretical support for related research, and provide theoretical guidance for equipment material selection and new material development. Summary of the invention

[0003] The purpose of the present invention is to provide an electrochemical corrosion sample for use in harsh environments and a preparation method thereof, so as to solve the problem of complex process of the existing electrochemical corrosion sample preparation method and the problem of nitric acid leakage and destruction of the sample. At the same time, the sample is easy to disassemble and replace. When the same sample is replaced after testing, only the special sample can be replaced, which can shorten the sample replacement time and save the use of preparation materials and sample materials.

[0004] The technical solution of the present invention is:

[0005] An electrochemical corrosion sample for use in harsh environments, the electrochemical corrosion sample comprising a sample, a gasket I, a connecting screw, a glass tube, a gasket II and a bolt, and the specific structure is as follows:

[0006] The sample is a cylinder with a hemispherical end, a hole is opened in the center of the flat end face of the sample, an internal thread I is arranged in the hole, the side where the internal thread I of the sample is located is fastened with one end of the connecting screw by thread, and a gasket I for enhancing sealing is arranged at the connection between the sample and the connecting screw; the other end of the connecting screw is fastened with the bolt by thread, and a gasket II for enhancing sealing is arranged at the connection between the connecting screw and the bolt; a glass tube is added to the outside of the connecting screw, one end of the glass tube is pressed tightly on the gasket I, and the other end of the glass tube is pressed tightly on the gasket II;

[0007] One end of the bolt is a stud with external threads, where the external threads are fastened to the connecting screw by threads, and the other end of the bolt is a cylindrical terminal, where the wire is connected to the sample;

[0008] The glass tube surrounds the connecting screw, one end of the connecting screw is fastened to the stud of the bolt by the spiral movement of the bolt, and the other end of the connecting screw is fastened to one side of the sample by the spiral movement of the sample. Under the action of the threaded fastening at both ends, the glass tube is pressed against the gaskets at both ends to achieve secondary sealing of the sample.

[0009] The electrochemical corrosion sample used in harsh environments has an appearance similar to the shape of a round-headed bullet. The sample has a cylinder as the sample body, one end of the sample body is a hemisphere, and the other end of the sample body is provided with a circular hole along the axial direction and an internal thread I is provided in the circular hole. One side where the internal thread I is located is fastened to the connecting screw by a thread, and the glass tube and the gasket I are compressed by fastening the sample and the connecting screw.

[0010] The electrochemical corrosion sample used in harsh environments has a connecting screw with a cylinder as the connecting screw body, a circular hole is opened at one end of the connecting screw body along the axial direction and an internal thread II is set in the circular hole, where the internal thread II is fastened to the bolt through threads, and the glass tube and gasket II are pressed tightly by fastening the connecting screw and the bolt, and the other end of the connecting screw body has an external thread, and the diameter of the external thread is equal to the diameter of the internal thread I of the sample.

[0011] The bolt used for electrochemical corrosion samples in harsh environments is composed of a stud, a bolt head and a round rod protruding at one end as a terminal, which are coaxially connected as a whole. The thread diameter of the stud is equal to the diameter of the internal thread II on the connecting screw. When doing an electrochemical test experiment, the alligator clip of the electrode connecting wire of the electrochemical workstation is fixed on the terminal, and the stud of the bolt is fastened to one end of the connecting screw through a thread, and the glass tube and the gasket II there are pressed tightly.

[0012] The bolt head of the electrochemical corrosion sample used in harsh environments is cylindrical or hexagonal prism-shaped, wherein: when the bolt head is cylindrical, the bolt head diameter is equal to the outer diameter of the glass tube; when the bolt head is hexagonal prism, the length of the hexagonal opposite sides of the bolt head is equal to the outer diameter of the glass tube.

[0013] The electrochemical corrosion sample used in harsh environment has a column length of 5-10 mm, a bolt head thickness of 1-5 mm, and a terminal column that is a cylinder with a length of 5-20 mm and a diameter of 1-3 mm.

[0014] The electrochemical corrosion sample used in harsh environments has an inner diameter of gasket I equal to the diameter of the internal thread I of the sample, an inner diameter of gasket II equal to the diameter of the internal thread II of the connecting screw, and outer diameters of gasket I and gasket II greater than or equal to the diameter of the glass tube. Gasket I and gasket II are respectively used at the connection between the bolt and the glass tube and the connecting screw, and at the connection between the sample and the glass tube and the connecting screw.

[0015] The electrochemical corrosion sample used in harsh environments is made of the same material as the connecting screw, the bolt is made of copper, silver, aluminum or tungsten with good conductivity, and the gasket I and gasket II are made of polytetrafluoroethylene.

[0016] The method for preparing an electrochemical corrosion sample for use in a harsh environment comprises the following steps: when preparing the sample, first fix the sample, a gasket I and a connecting screw together, and tighten the internal thread I of the sample with the external thread of the connecting screw; then pass the connecting screw through the glass tube, and then tighten the stud of the bolt with the internal thread II of the connecting screw; when used for an electrochemical experiment, put an electrode sealing ring on the prepared sample, insert it into the electrode hole, tighten the sealing bolt of the electrolytic cell, and fix the alligator clip of the electrode connecting wire of the electrochemical workstation on the terminal; when conducting a parallel test of a sample or a test under multiple conditions, take out the electrochemical corrosion sample, unscrew the sample, and replace it with a new sample.

[0017] In the method for preparing an electrochemical corrosion sample for use in a harsh environment, a glass tube surrounds a connecting screw to seal the connecting screw, the connecting screw is fastened to a bolt and the sample through threads, and the glass tube is tightly combined with gasket I and gasket II to complete secondary sealing of the sample.

[0018] The design concept of the present invention is:

[0019] The present invention is based on the existing engineering problem: during the spent fuel reprocessing process, some key equipment works under variable and extremely harsh conditions for a long time, and there is a situation where the material is severely corroded and threatens the safe operation of the equipment. In order to systematically illustrate the corrosion behavior of various materials in different media, electrochemical corrosion testing is an indispensable part. However, the existing electrochemical corrosion sample preparation method has some drawbacks, so a new method for preparing electrochemical samples that effectively overcomes the drawbacks of existing electrochemical corrosion samples is developed to protect the samples from damage, effectively shorten the sample replacement time, and save the use of preparation materials and sample materials.

[0020] In the present invention, the sample is made into a warhead shape similar to a round-headed bullet, the sample is connected to a bolt with a terminal on the head by a connecting screw, the outside of the electrochemical corrosion sample is sealed by a glass tube, and when conducting an electrochemical test experiment, the electrochemical workstation transmits electrochemical signals by connecting to the terminal on the sample.

[0021] There are limited materials that can be used for a long time in boiling nitric acid. From the perspective of long-term use and safety, glass tubes are selected as sealing devices for samples. The thickness of the glass tubes is as large as possible to avoid accidental breakage. In order to make it easier to connect the sample to the electrochemical workstation, terminals are set on the special bolts. Copper is selected as the material of the special bolts because copper has excellent conductivity and good machinability. In order to protect the sample, gaskets are set at the joints of the various parts of the sample to enhance the sealing. If ethylene oxide is used as a gasket, it will be toxic to a certain extent, so polytetrafluoroethylene material that is harmless to the human body is selected. During use, the connecting threads need to be tightened to form a sealed space to protect the sample.

[0022] In order to save energy and protect the environment, the size of the entire sample is small, and energy-intensive welding, sintering and high-temperature heating steps are not required during the sample preparation process. When conducting parallel tests on one sample or multiple condition tests, only the special sample can be replaced.

[0023] In order to prevent nitric acid leakage and damage to the sample, the connecting screw is made of the same material as the sample to be tested. Even if a small amount of nitric acid enters the glass tube, it will not affect the test results, and the sample parts can continue to be used after cleaning or replacement.

[0024] The present invention has the following advantages and beneficial effects:

[0025] 1. The polytetrafluoroethylene material, copper material and glass material used in the present invention have good biocompatibility, are harmless to the human body and are highly safe.

[0026] 2. Each part of the electrochemical sample designed by the present invention can be easily disassembled and installed, and the replacement of the sample is more convenient.

[0027] 3. The various parts of the electrochemical sample designed by the present invention are fastened by threads, and when conducting parallel tests on one sample or tests under multiple conditions, only the special sample can be replaced.

[0028] 4. The polytetrafluoroethylene gasket and glass tube in the present invention are resistant to acid, alkali and high temperature, and can be applied to various corrosive working conditions. The slight expansion produced under high temperature conditions will strengthen the fastening between the various parts.

[0029] 5. The electrochemical samples designed in the present invention are relatively small in size, and the sample preparation process does not require energy-intensive welding, sintering, and high-temperature heating steps. In addition, multiple special samples can be replaced, and the cost is controlled without affecting the use of the samples, thereby having high economic benefits.

[0030] 6. The size of the electrochemical sample designed by the present invention is relatively free and can be flexibly adjusted according to different experimental requirements.

[0031] 7. The present invention can be applied to the preparation of electrochemical samples that need to work in harsh environments, and to the study of the electrochemical corrosion behavior of materials in harsh environments. It can effectively avoid the situation in which samples prepared by existing electrochemical sample preparation methods are damaged by electrolyte solutions, and can work for a long time in strong acid, strong alkaline, high temperature and high pressure environments, thereby increasing the reliability of experimental data obtained from electrochemical tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the main structure of the electrochemical corrosion sample of the present invention.

[0033] Figure 2 This is a schematic diagram of a specially made sample of the present invention.

[0034] Figure 3 It is a schematic diagram of the connecting screw of the present invention.

[0035] Figure 4 It is a schematic diagram of the special bolt of the present invention.

[0036] Figure 5 It is a schematic diagram of the decomposition structure of the electrochemical corrosion sample of the present invention.

[0037] In the figure: 1. sample; 2. gasket I; 3. connecting screw; 4. glass tube; 5. gasket II; 6. bolt; 7. hemisphere; 8. sample body; 9. internal thread I; 10. external thread; 11 connecting screw body; 12. internal thread II; 13. stud; 14. bolt head; 15. terminal. DETAILED DESCRIPTION

[0038] like Figure 1-Figure 5 As shown, the present invention designs an electrochemical corrosion sample for use in harsh environments, the electrochemical corrosion sample includes a sample 1, a gasket I2, a connecting screw 3, a glass tube 4, a gasket II5 and a bolt 6, and the specific structure is as follows:

[0039] Sample 1 is made into a warhead shape similar to a round-headed bullet, which is conducive to more uniform transmission of electrochemical signals. If the experiment requires, it can also be made into other shapes that are conducive to electrochemical signal transmission. A hole is opened in the center of the flat end face of sample 1, and an internal thread I9 is ​​set in the hole. The side where the internal thread I9 of sample 1 is located is fastened to one end of the connecting screw 3 by thread, and a gasket I2 is provided at the connection between sample 1 and the connecting screw 3 to enhance the sealing; the other end of the connecting screw 3 is fastened to the bolt 6 by thread, and a gasket II5 is provided at the connection between the connecting screw 3 and the bolt 6 to enhance the sealing; a glass tube 4 is added to the outside of the connecting screw 3, one end of the glass tube 4 is pressed tightly against the gasket I2, and the other end of the glass tube 4 is pressed tightly against the gasket II5;

[0040] One end of the bolt 6 is a stud 13 with an external thread, where the external thread is fastened to the connecting screw 3 by thread, and the other end of the bolt 6 is a cylindrical terminal 15, where the wire is connected to the sample 1 through the terminal 15;

[0041] The glass tube 4 surrounds the connecting screw 3, one end of the connecting screw 3 is fastened to the stud 13 of the bolt 6 by the spiral movement of the bolt 6, and the other end of the connecting screw 3 is fastened to one side of the sample 1 by the spiral movement of the sample 1. Under the action of the threaded fastening at both ends, the glass tube 4 is pressed against the gaskets at both ends, completing the secondary sealing of the sample.

[0042] like Figure 1 , Figure 2 As shown, the sample 1 and the connecting screw 3 are made of the same material, and one end of the sample 1 is a cylinder with a hemispherical body, and its appearance is similar to the shape of a round pistol bullet. The length and diameter of the sample 1 can be flexibly adjusted within the allowable range. The sample 1 uses a cylinder as the sample body 8, one end of the sample body 8 is a hemispherical body 7, and the other end of the sample body 8 is provided with a circular hole along the axial direction and an internal thread I9 is ​​provided in the circular hole. The side where the internal thread I9 is ​​located is fastened with the connecting screw 3 by thread. The fastening of the sample 1 and the connecting screw 3 presses the glass tube 4 and the gasket I2 to perform secondary sealing.

[0043] like Figure 1 , Figure 3 As shown, the connecting screw 3 is made of the same material as the sample 1. Such a design allows the sample to maintain normal operation without affecting the test results when facing the problem of electrolyte leakage. The connecting screw 3 is a cylindrical connecting screw body 11. One end of the connecting screw body 11 is provided with a circular hole along the axial direction and an internal thread II12 is provided in the circular hole. Here, the internal thread II12 is fastened with the bolt 6 by threads. The length and inner diameter of the internal thread II12 can be freely adjusted within the allowable range. The fastening of the connecting screw 3 and the bolt 6 presses the glass tube 4 and the gasket II5. The other end of the connecting screw body 11 has an external thread 10, and the diameter of the external thread 10 is equal to the diameter of the internal thread I9 of the sample 1.

[0044] like Figure 1 , Figure 4As shown, the bolt 6 is composed of a stud 13, a bolt head 14 and a round rod protruding at one end as a terminal 15 connected coaxially and integrally, and is made of a material with good conductivity such as copper, silver, aluminum or tungsten. The length of the stud 13 is 5 to 10 mm, the thickness of the bolt head 14 is 1 to 5 mm, and the terminal 15 is a cylinder with a length of 5 to 20 mm and a diameter of 1 to 3 mm. The specific size can be flexibly adjusted according to experimental needs. The thread diameter of the stud 13 is equal to the diameter of the internal thread II12 on the connecting screw 3. The bolt head 14 can be in the shape of a cylinder, a hexagonal prism, etc., wherein: if the bolt head 14 is a cylinder, the diameter of the bolt head 14 is equal to the outer diameter of the glass tube 4; if the bolt head 14 is a hexagonal prism, the length of its hexagonal opposite sides is equal to the outer diameter of the glass tube 4. When doing electrochemical test experiments, the electrode connection line crocodile clip of the electrochemical workstation is fixed on the terminal 15, the stud 13 of the bolt 6 is fastened to one end of the connecting screw 3 through threads, and the glass tube 4 and the gasket II5 here are pressed tightly.

[0045] like Figure 1 , Figure 5 As shown, the glass tube 4 surrounds the connecting screw 3 to seal the connecting screw 3. Since the connecting screw 3 is fastened to the bolt 6 and the sample 1 through threads, the glass tube 4 is tightly combined with the gasket I2 and the gasket II5 to complete the secondary sealing of the sample. The length and outer diameter of the glass tube 4 are reasonably adjusted according to the length of the connecting screw 3, and the thickness should not be too small.

[0046] like Figure 1 , Figure 5 As shown, gasket I2 and gasket II5 are made of polytetrafluoroethylene material, the inner diameter of gasket I2 needs to be equal to the diameter of internal thread I9 of sample 1, the inner diameter of gasket II5 needs to be equal to the diameter of internal thread II12 of connecting screw 3, the outer diameter of gasket I2 and gasket II5 needs to be greater than or equal to the diameter of glass tube 4, gasket I2 and gasket II5 are respectively used at the connection between bolt 6 and glass tube 4 and connecting screw 3, and at the connection between sample 1 and glass tube 4 and connecting screw 3.

[0047] When preparing the sample, first fix the sample 1, the gasket I2 and the connecting screw 3 together, and tighten the internal thread I9 of the sample 1 with the external thread 10 of the connecting screw 3; then pass the connecting screw 3 through the glass tube 4, and then tighten the stud 13 of the bolt 6 with the internal thread II12 of the connecting screw 3; when used for electrochemical experiments, put the prepared sample on the electrode sealing ring, insert it into the electrode hole and tighten the sealing bolt of the electrolytic cell, and fix the electrode connecting wire crocodile clip of the electrochemical workstation on the terminal 15; when conducting parallel tests on one sample or multiple conditions tests, the electrochemical corrosion sample can be taken out and the sample can be unscrewed and replaced with a new sample.

[0048] The implementation results show that the present invention has developed a durable electrochemical corrosion sample suitable for a variety of variable working environments and used in harsh environments. This sample is put into the corrosion electrochemical experiment of key equipment materials, and the electrochemical test results are combined with other experimental results and product analysis to systematically explain the corrosion behavior of various materials in different media, provide theoretical support for related research, and provide theoretical guidance for equipment material selection and new material development.

[0049] The above is only the best example of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An electrochemical corrosion sample for use in harsh environments, characterized in that: The electrochemical corrosion sample includes a sample, a gasket I, a connecting screw, a glass tube, a gasket II and a bolt, and the specific structure is as follows: The sample is a cylinder with a hemispherical end, a hole is opened in the center of the flat end face of the sample, an internal thread I is arranged in the hole, the side where the internal thread I of the sample is located is fastened with one end of the connecting screw by thread, and a gasket I for enhancing sealing is arranged at the connection between the sample and the connecting screw; the other end of the connecting screw is fastened with the bolt by thread, and a gasket II for enhancing sealing is arranged at the connection between the connecting screw and the bolt; a glass tube is added to the outside of the connecting screw, one end of the glass tube is pressed tightly on the gasket I, and the other end of the glass tube is pressed tightly on the gasket II; One end of the bolt is a stud with external threads, where the external threads are fastened to the connecting screw by threads, and the other end of the bolt is a cylindrical terminal, where the wire is connected to the sample; The glass tube surrounds the connecting screw, one end of the connecting screw is fastened to the stud of the bolt by the spiral movement of the bolt, and the other end of the connecting screw is fastened to one side of the sample by the spiral movement of the sample. Under the action of the threaded fastening at both ends, the glass tube is pressed against the gaskets at both ends to achieve secondary sealing of the sample.

2. The electrochemical corrosion sample for use in harsh environments according to claim 1, characterized in that: The appearance of the sample is similar to the shape of a round-headed bullet. The sample has a cylindrical body as the sample body, one end of the sample body is a hemisphere, and a circular hole is opened along the axial direction at the other end of the sample body and an internal thread I is set in the circular hole. The side where the internal thread I is located is fastened to the connecting screw through a thread, and the glass tube and the gasket I are pressed tightly by fastening the sample and the connecting screw.

3. The electrochemical corrosion sample for use in harsh environments according to claim 1, characterized in that: The connecting screw has a cylinder as its main body, a circular hole is opened at one end of the main body of the connecting screw along the axial direction and an internal thread II is arranged in the circular hole, wherein the internal thread II is fastened with the bolt through threads, and the glass tube and the gasket II are pressed tightly by fastening the connecting screw and the bolt, and the other end of the main body of the connecting screw has an external thread, and the diameter of the external thread is equal to the diameter of the internal thread I of the sample.

4. The electrochemical corrosion sample for use in harsh environments according to claim 1, characterized in that: The bolt is composed of a stud, a bolt head and a round rod protruding at one end as a terminal, which are coaxially connected as a whole. The thread diameter of the stud is equal to the diameter of the internal thread II on the connecting screw. When doing electrochemical test experiments, the alligator clip of the electrode connecting line of the electrochemical workstation is fixed on the terminal, and the stud of the bolt is fastened to one end of the connecting screw through threads, and the glass tube and the gasket II here are pressed tightly.

5. The electrochemical corrosion sample for use in harsh environments according to claim 4, characterized in that: The bolt head is in the shape of a cylinder or a hexagonal prism, wherein: when the bolt head is a cylinder, the diameter of the bolt head is equal to the outer diameter of the glass tube; when the bolt head is a hexagonal prism, the length of the hexagonal opposite sides of the bolt head is equal to the outer diameter of the glass tube.

6. The electrochemical corrosion sample for use in harsh environments according to claim 4, characterized in that: The length of the stud is 5 to 10 mm, the thickness of the bolt head is 1 to 5 mm, and the terminal is a cylinder with a length of 5 to 20 mm and a diameter of 1 to 3 mm.

7. The electrochemical corrosion sample for use in harsh environments according to claim 1, characterized in that: The inner diameter of gasket I is equal to the diameter of the internal thread I of the sample, the inner diameter of gasket II is equal to the diameter of the internal thread II of the connecting screw, the outer diameters of gasket I and gasket II are greater than or equal to the diameter of the glass tube, and gasket I and gasket II are respectively used at the connection between the bolt and the glass tube and the connecting screw, and at the connection between the sample and the glass tube and the connecting screw.

8. The electrochemical corrosion sample for use in harsh environments according to claim 1, characterized in that: The sample and the connecting screw are made of the same material. The bolt is made of copper, silver, aluminum or tungsten with good conductivity. Gasket I and gasket II are made of polytetrafluoroethylene.

9. A method for preparing an electrochemical corrosion sample for use in a harsh environment according to any one of claims 1 to 8, characterized in that: When preparing the sample, first fix the sample, gasket I and connecting screw together, and tighten the internal thread I of the sample with the external thread of the connecting screw; then pass the connecting screw through the glass tube, and then tighten the stud of the bolt with the internal thread II of the connecting screw; when used for electrochemical experiments, put the prepared sample on the electrode sealing ring, insert it into the electrode hole and tighten the sealing bolt of the electrolytic cell, and fix the electrode connecting wire crocodile clip of the electrochemical workstation on the terminal; when conducting parallel tests of one sample or multiple conditions tests, take out the electrochemical corrosion sample, unscrew the sample, and replace it with a new sample.

10. The method for preparing an electrochemical corrosion sample for use in a harsh environment according to claim 9, characterized in that: The glass tube surrounds the connecting screw to seal the connecting screw. The connecting screw is fastened to the bolt and the sample through threads. The glass tube is tightly combined with gasket I and gasket II to complete the secondary sealing of the sample.

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