Corrosion sensor and method of manufacturing corrosion sensor

Abstract

To provide a corrosion sensor capable of more accurately detecting a corrosion penetration state, and a method for manufacturing the corrosion sensor.SOLUTION: The corrosion sensor 1 according to the present disclosure includes the working electrode 10 that is made of a metal and has the space 15 in which a fluid is sealed, the insulating layer 20 that is disposed on the surface of the working electrode 10 so as to expose the exposed portion 11, which is a portion of the surface of the working electrode 10, and the counter electrode 30 that is disposed on the insulating layer 20 and has a nobler potential than the working electrode 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a corrosion sensor and a method for manufacturing a corrosion sensor. [Background technology]

[0002] 2. Description of the Related Art Corrosion sensors are used to detect corrosion of refrigerant piping in refrigeration cycle devices such as air conditioners.

[0003] For example, Patent Document 1 discloses a refrigeration cycle device having a refrigerant pipe, an ACM sensor that detects a corrosion current, and a processing unit that determines corrosion of the refrigerant pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-36621 Summary of the Invention [Problem to be solved by the invention]

[0005] The refrigeration cycle device described in Patent Document 1 still has room for improvement in terms of accurately detecting the state of corrosion penetration in refrigerant pipes and the like using corrosion current.

[0006] The present disclosure provides a corrosion sensor and a method for manufacturing the corrosion sensor that can detect corrosion penetration with higher accuracy. [Means for solving the problem]

[0007] A corrosion sensor according to one aspect of the present disclosure includes: a working electrode formed of metal and having a space that seals a fluid; an insulating layer disposed on the surface of the working electrode so as to expose an exposed portion that is a part of the surface of the working electrode; a counter electrode disposed on the insulating layer and having a more noble potential than the working electrode; Equipped with.

[0008] A method for manufacturing a corrosion sensor according to one aspect of the present disclosure includes: preparing a tubular working electrode made of metal; forming an insulating layer on the surface of the working electrode so as to expose an exposed portion that is a part of the surface of the working electrode; forming a counter electrode having a more noble potential than the working electrode on a surface of the insulating layer; introducing a fluid or a solid into a space of the working electrode from an end of the working electrode; sealing an end of the working electrode; Includes: [Effects of the Invention]

[0009] According to the present disclosure, a corrosion sensor capable of accurately detecting corrosion penetration and a method for manufacturing the corrosion sensor are provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically illustrating a corrosion sensor 1 according to a first embodiment of the present disclosure. [Figure 2] AA cross section of the corrosion sensor in Figure 1 [Figure 3] Graph showing the relationship between the corrosion current detected by the corrosion sensor of FIG. 1 and time. [Figure 4] Flowchart for explaining a method for manufacturing a corrosion sensor [Figure 5] Partial cross-sectional view illustrating part of the manufacturing process for the corrosion sensor [Figure 6] Partial cross-sectional view illustrating part of the manufacturing process for the corrosion sensor [Figure 7] Partial cross-sectional view illustrating part of the manufacturing process for the corrosion sensor [Figure 8] Partial cross-sectional view illustrating part of the manufacturing process for the corrosion sensor [Figure 9] Cross-sectional view illustrating part of the manufacturing process for the corrosion sensor [Figure 10]Cross-sectional view illustrating part of the manufacturing process for the corrosion sensor [Figure 11] FIG. 10 is a diagram illustrating a corrosion sensor according to a second embodiment. [Figure 12] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the second embodiment. [Figure 13] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the second embodiment. [Figure 14] FIG. 10 is a diagram illustrating a corrosion sensor according to a third embodiment. [Figure 15] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the third embodiment. [Figure 16] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the third embodiment. [Figure 17] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the third embodiment. [Figure 18] 10 is a flowchart illustrating a method for manufacturing a corrosion sensor according to a modification of the third embodiment. [Figure 19A] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the modified example of the third embodiment. [Figure 19B] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the modified example of the third embodiment. [Figure 20] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the fourth embodiment. [Figure 21] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the fourth embodiment. [Figure 22] 10A and 10B are cross-sectional views illustrating a part of a manufacturing process of the corrosion sensor according to the fourth embodiment. [Figure 23] FIG. 10 is a diagram illustrating a corrosion sensor according to a fifth embodiment. [Figure 24] A flowchart for explaining the manufacturing method of the corrosion sensor of FIG. 23. [Figure 25] Cross-section of part of the manufacturing process for the corrosion sensor in Figure 23 [Figure 26] Cross-section of part of the manufacturing process for the corrosion sensor in Figure 23 [Figure 27] Cross-section of part of the manufacturing process for the corrosion sensor in Figure 23 DETAILED DESCRIPTION OF THE INVENTION

[0011] (Background to this disclosure) Refrigeration cycle devices such as air conditioners use refrigerant piping made of copper pipes. Detecting corrosion of copper pipes has been studied to prevent refrigerant leakage. For example, Patent Document 1 discloses detecting corrosion current in refrigerant piping using an ACM sensor.

[0012] The ACM sensor detects the corrosion current flowing between the substrate and the cathode through a water film formed on the sensor surface, and determines corrosion based on changes in the corrosion current detected by the ACM sensor.

[0013] ACM sensors can detect the occurrence of localized corrosion by measuring corrosion current, but it is difficult to detect whether the metal that makes up the refrigerant piping has been penetrated by corrosion.

[0014] In order to more accurately grasp the corrosion state of metals that make up refrigerant pipes and the like, it is necessary to accurately detect the corrosion penetration state.

[0015] Therefore, the present inventors have studied a corrosion sensor and a method for manufacturing a corrosion sensor that can detect corrosion penetration with higher accuracy, and have arrived at the following invention.

[0016] (Embodiment 1) [Overall configuration] Fig. 1 is a diagram schematically illustrating a corrosion sensor 1 according to a first embodiment of the present disclosure. Fig. 2 is a partial cross-sectional view of the corrosion sensor taken along line AA in Fig. 1. Note that the ammeter 40 shown in Fig. 1 is omitted in Fig. 2.

[0017] The corrosion sensor 1 is a sensor for detecting a corrosion current. The corrosion sensor 1 includes a working electrode 10, an insulating layer 20, and a counter electrode 30, as shown in FIGS.

[0018] A portion of the surface of the working electrode 10 is provided with an exposed portion 11 that is exposed to the outside. Liquid, such as condensed water generated inside a refrigeration cycle device, adheres to the exposed portion 11. When liquid adheres to the exposed portion 11, corrosion progresses in the exposed portion 11. As the corrosion progresses, a corrosion current flows between the working electrode 10 and the counter electrode 30 via the liquid adhering to the exposed portion 11. In this embodiment, the corrosion current is measured using an ammeter 40 shown in FIG. 1. By monitoring changes in the corrosion current, the progress of corrosion of the working electrode 10 can be understood. Note that the ammeter 40 is not an essential component of the corrosion sensor 1. In this embodiment, localized corrosion associated with stress corrosion cracking can be detected by measuring the corrosion current.

[0019] The working electrode 10 is made of a metal for which corrosion is to be detected. The working electrode 10 is made of, for example, copper, a phosphorus copper alloy, aluminum, an aluminum manganese alloy, or an aluminum zinc alloy. In this embodiment, an example in which the working electrode 10 is made of copper will be described.

[0020] The working electrode 10 has a space 15 capable of sealing a fluid. In this embodiment, the working electrode 10 is tubular, as shown in FIG. 1, and has a U-shaped bent portion 12. In this embodiment, one end 13 of the working electrode 10 is sealed with a sealant 50, and the other end 14 of the working electrode 10 is sealed with a valve 61. The sealant 50 may be, for example, a metal flare cap. Alternatively, a resin cap containing epoxy resin may be used as the sealant 50. The bent portion 12 of the working electrode 10 is a location on the working electrode 10 where stress corrosion cracking is likely to occur due to the presence of residual stress. Therefore, if an exposed portion 11 is provided at a portion of the bent portion 12 on the surface of the working electrode 10, the corrosion current at the bent portion 12 can be detected to monitor stress corrosion cracking.

[0021] A fluid is sealed in the space 15 inside the working electrode 10. In this embodiment, an example will be described in which the fluid is a gas. The pressure of the gas sealed in the space 15 inside the working electrode 10 is higher than atmospheric pressure. "A gas is sealed in the space 15 inside the working electrode 10" means that the space 15 inside the working electrode 10 is sealed so that the gas does not leak from the space 15 inside the working electrode 10. In this embodiment, the space 15 inside the working electrode 10 is filled with a gas containing, for example, air, nitrogen, helium, or carbon dioxide. The type of gas should be selected taking into consideration safety in the event of leakage from the space 15 inside the working electrode 10.

[0022] An exposed portion 11 exposed to the outside is provided on a portion of the surface of the working electrode 10. The exposed portion 11 is formed, for example, in a circular shape with a diameter of 0.5 mm or more and 5 mm or less. Liquid, such as condensed water generated inside a refrigeration cycle device, adheres to the exposed portion 11. When liquid adheres to the exposed portion 11, corrosion progresses in the exposed portion 11. As the corrosion progresses, a corrosion current flows between the working electrode 10 and the counter electrode 30 via the liquid adhering to the exposed portion 11.

[0023] FIG. 3 is a graph showing the relationship between the corrosion current detected by the corrosion sensor 1 of FIG. 1 and time. In the graph of the corrosion current shown in FIG. 3, a spike current, where the corrosion current suddenly rises, is detected in the background current, which is a small change in the current value. As the corrosion progresses further, the working electrode 10 is penetrated by the corrosion, causing the internal fluid to leak. The leakage of the fluid from the working electrode 10 causes fluctuations in the liquid adhering to the exposed portion 11, resulting in disturbances in the background current. The leakage of the fluid from the through-hole due to corrosion causes fluctuations on the surface of the liquid adhering to the exposed portion 11, and these fluctuations are detected as disturbances in the background current.

[0024] In the graph of FIG. 3, a background current with an amplitude of approximately 0.1 μA to 0.5 μA is detected after time T1. After time T2, the amplitude of the background current becomes larger, indicating that a disturbance has occurred in the background current. This disturbance in the background current is caused by the working electrode 10 being penetrated by corrosion, causing the internal fluid to leak. Therefore, it can be seen that penetration due to corrosion occurred at the stage of time T2. By providing a space 15 inside the working electrode 10 and sealing in a fluid with a pressure higher than atmospheric pressure, it is possible to detect the disturbance in the background current when the working electrode 10 is penetrated by corrosion and the internal fluid leaks.

[0025] The insulating layer 20 is disposed on the surface of the working electrode 10. As shown in FIG. 2 , the insulating layer 20 has a space 21 that exposes the exposed portion 11, which is a portion of the surface of the working electrode 10. That is, a circular hole is provided in the insulating layer 20, exposing a portion of the surface of the working electrode 10 as the exposed portion 11. Because the insulating layer 20 has a circular hole, the insulating layer 20 is disposed so as to surround the periphery of the exposed portion 11. By providing the insulating layer 20 so as to surround the exposed portion 11, it becomes easier to retain liquid in the exposed portion 11, and corrosion current can be detected more efficiently. In this embodiment, the space 21 is provided so that the space 21 in the insulating layer 20 is located at the bent portion 12 of the working electrode 10. Furthermore, in this embodiment, the insulating layer 20 is not provided on the straight pipe portion of the working electrode 10, but the straight pipe portion is not included in the exposed portion 11 of the working electrode 10.

[0026] The insulating layer 20 is formed of an insulating material, such as a resin containing epoxy resin. The insulating layer 20 is formed to a thickness of, for example, 10 μm or more and 500 μm or less. Forming the insulating layer 20 to a thickness of 10 μm or more can suppress short-circuiting between the working electrode 10 and the counter electrode 30. Furthermore, forming the insulating layer to a thickness of 500 μm or less can supply dissolved oxygen in the liquid to the exposed portion 11, which is a part of the surface of the working electrode 10. Therefore, the corrosion current detected by the corrosion sensor 1 can be treated as a current representative of corrosion of the surface of a metal made of the same material as the working electrode 10.

[0027] The counter electrode 30 is formed on the surface of the insulating layer 20. More specifically, it is formed on the surface of the insulating layer 20, at least in part around the space 21 of the insulating layer 20. The counter electrode 30 is laminated on the insulating layer 20 so that the counter electrode 30 and the working electrode 10 are insulated from each other when no liquid is attached to the exposed portion 11. In other words, the counter electrode 30 and the working electrode 10 are arranged with the insulating layer 20 sandwiched between them in the lamination direction. The counter electrode 30 is arranged to face the working electrode 10 with the insulating layer 20 sandwiched between them in the lamination direction. The counter electrode 30 is also arranged so as not to be in direct contact with the working electrode 10. The distance between the counter electrode 30 and the working electrode 10 in the lamination direction is determined by the thickness of the insulating layer 20. In this embodiment, the insulating layer 20 is laminated on the surface of the working electrode 10, and the counter electrode 30 is laminated on the insulating layer 20. The counter electrode 30 is formed of a conductive material having a more noble potential than the working electrode 10, such as silver or conductive carbon. When a liquid adheres to the exposed portion 11, a corrosion current flows between the working electrode 10 and the counter electrode 30 via the liquid.

[0028] The corrosion sensor 1 is placed near a refrigerant pipe inside a refrigeration cycle device such as an air conditioner. The refrigerant flowing inside the refrigeration cycle device can cause the surface temperature of the refrigerant pipe to become lower than the outside air temperature, resulting in condensation. The corrosion sensor 1 retains a liquid such as condensed water on the exposed portion 11, and detects a corrosion current flowing between the working electrode 10 and the counter electrode 30 via the attached liquid. When the corrosion sensor 1 is used to detect corrosion in the refrigerant pipe of a refrigeration cycle device, the state of corrosion in the refrigerant pipe can be detected by forming the working electrode 10 from the same material as the refrigerant pipe.

[0029] As corrosion of the exposed portion 11 of the working electrode 10 progresses, hydroxide ions are generated. When the generation of hydroxide ions causes liquid to adhere to the exposed portion 11, and the working electrode 10 and the counter electrode 30 become conductive, a corrosion current flows between the working electrode 10 and the counter electrode 30. By forming the counter electrode 30 from a material having a more noble potential than the working electrode 10, corrosion progresses preferentially in the exposed portion 11 of the working electrode 10.

[0030] [Corrosion sensor manufacturing method] Next, a method for manufacturing the corrosion sensor 1 will be described with reference to Figs. 4 to 10. Fig. 4 is a flowchart illustrating a method for manufacturing the corrosion sensor 1. Figs. 5 to 8 are partial cross-sectional views illustrating part of the manufacturing process of the corrosion sensor 1. Figs. 9 and 10 are cross-sectional views illustrating part of the manufacturing process of the corrosion sensor 1. Figs. 5 to 8 are cross-sectional views of the tube constituting the working electrode 10 cut along the circumferential direction, and Figs. 9 and 10 are cross-sectional views of the tube constituting the working electrode 10 cut along a direction intersecting the circumferential direction.

[0031] First, in step S1, working electrode 10 is prepared. Working electrode 10 is formed, for example, by bending a tube made of copper. At this time, one end 13 of working electrode 10 (see FIGS. 1 and 9) is sealed in advance with sealing material 50. Alternatively, working electrode 10 may be a tube having an opening at one end and the other end sealed in advance.

[0032] Next, in step S2, an insulating layer 20 is formed on the surface of the working electrode 10 so as to expose an exposed portion 11, which is a portion of the working electrode 10. To form the insulating layer 20, first, as shown in FIG. 5, the portion of the surface of the working electrode 10 that will become the exposed portion 11 is masked using tape 60. Then, as shown in FIG. 6, the bend portion 12, including the masked portion, is covered with a resin such as epoxy resin. Furthermore, as shown in FIG. 7, when the tape 60 is removed, an insulating layer 20 is formed that has a space 21 for exposing the exposed portion 11, which is a portion of the surface of the working electrode 10.

[0033] Next, in step S3, a counter electrode 30 having a potential more noble than that of the working electrode 10 is formed on the surface of the insulating layer 20. The counter electrode 30 can be formed by applying a conductive paste such as a silver paste or a carbon paste to the surface of the insulating layer 20 and drying it.

[0034] Next, in step S4, a fluid is introduced into the space 15 of the working electrode 10 from the end of the working electrode 10. Here, an example in which a gas is introduced as the fluid will be described. In this embodiment, as shown in FIG. 9 , a valve 61 is provided at the other unsealed end 14 of the working electrode 10. A gas cylinder 62 is connected to the other end of the working electrode 10. In this embodiment, in step S4, the valve 61 is opened to inject gas into the space 15 of the working electrode 10, thereby increasing the gas pressure inside the space 15 of the working electrode 10 above atmospheric pressure. The gas pressure inside the space 15 of the working electrode 10 can be, for example, approximately 4.15 MPa, which is the design pressure of the refrigerant in an air conditioner. The gas pressure can be changed to any value depending on the target for corrosion detection. By injecting gas into the space 15 of the working electrode 10 using the gas cylinder 62, the pressure inside the space 15 can easily be increased above atmospheric pressure. The gas injected using the gas cylinder 62 can be, for example, air, nitrogen, helium, or carbon dioxide.

[0035] Next, in step S5, the end of the working electrode 10 is sealed. In this embodiment, one end 13 of the working electrode 10 is sealed in advance, and therefore, in step S5, the other end 14 of the working electrode 10 is sealed. In this embodiment, as shown in FIG. 10 , the other end 14 of the working electrode 10 can be sealed by removing the gas cylinder 62 and closing the valve 61.

[0036] In step S5, the end 14 of the working electrode 10 is sealed, and the corrosion sensor 1 is completed.

[0037] [effect] According to the above-described embodiment, the following effects can be achieved.

[0038] The corrosion sensor 1 includes a working electrode 10, an insulating layer 20, and a counter electrode 30. The working electrode 10 is made of metal and has a space 15 that seals a gas. The insulating layer 20 is disposed on the surface of the working electrode 10 so as to expose an exposed portion 11, which is a portion of the surface of the working electrode 10. The counter electrode 30 is disposed on the insulating layer 20 and has a more noble potential than the working electrode 10.

[0039] This configuration provides a corrosion sensor that can detect corrosion penetration with greater accuracy. By providing the working electrode 10 with the space 15 that contains a sealed fluid, it is possible to accurately detect corrosion penetration from the disturbance of the background current caused by leakage of the fluid inside the working electrode 10.

[0040] The fluid is a gas, and the pressure of the gas in the space 15 of the working electrode 10 is higher than atmospheric pressure.

[0041] With this configuration, the corrosion penetration state can be detected with higher accuracy.

[0042] The working electrode 10 is made of copper, a phosphorus copper alloy, aluminum, an aluminum manganese alloy, or an aluminum zinc alloy.

[0043] With this configuration, it is possible to provide a corrosion sensor that can detect corrosion currents of various metals.

[0044] The working electrode 10 is formed in a tubular shape with both ends sealed.

[0045] With this configuration, fluid can be easily injected into the space 15 inside the working electrode 10 .

[0046] The working electrode 10 has a U-shaped bent portion.

[0047] With this configuration, it is possible to detect corrosion current from the portion where residual stress exists, and therefore it is possible to detect stress corrosion cracking.

[0048] Both ends of the working electrode 10 are sealed with resin.

[0049] With this configuration, both ends of the working electrode 10 can be easily sealed.

[0050] The insulating layer 20 is made of epoxy resin.

[0051] With this configuration, the working electrode 10 and the counter electrode 30 can be reliably insulated from each other when no liquid is attached to the exposed portion 11.

[0052] The insulating layer 20 is formed to a thickness of 10 μm or more and 500 μm or less.

[0053] With this configuration, it is possible to supply oxygen to the liquid film formed on the surface of the working electrode 10 while maintaining insulation between the working electrode 10 and the counter electrode 30 when no liquid is held in the exposed portion 11, thereby enabling more efficient detection of corrosion current.

[0054] The counter electrode 30 is made of silver or conductive carbon.

[0055] With this configuration, the counter electrode 30 can be easily formed.

[0056] The gas includes air, nitrogen, helium, or carbon dioxide.

[0057] With this configuration, the corrosion penetration state can be detected with higher accuracy.

[0058] A corrosion current flows between the working electrode 10 and the counter electrode 30 via the liquid adhering to the exposed portion 11 .

[0059] With this configuration, it is possible to provide a corrosion sensor that can detect corrosion penetration with higher accuracy.

[0060] Furthermore, an ammeter 40 for detecting a current is provided.

[0061] With this configuration, the corrosion current flowing between the working electrode 10 and the counter electrode 30 can be measured.

[0062] The method for manufacturing the corrosion sensor 1 includes the steps of preparing a working electrode 10, forming an insulating layer 20, forming a counter electrode 30, introducing a fluid, and sealing an end 14 of the working electrode 10. In the step of preparing the working electrode 10, a tubular working electrode 10 made of metal is prepared. In the step of forming the insulating layer 20, an insulating layer is formed on the surface of the working electrode 10 so as to form an exposed portion 11, which is a portion of the surface of the working electrode 10. In the step of forming the counter electrode 30, a counter electrode 30 having a potential more noble than the working electrode 10 is formed on the surface of the insulating layer 20. In the step of introducing a fluid, a fluid is introduced from the end 14 of the working electrode 10 into a space 15 of the working electrode 10.

[0063] With this configuration, it is possible to provide a manufacturing method for a corrosion sensor that can detect corrosion penetration with higher accuracy.

[0064] A valve 61 is provided at the end 14 of the working electrode 10. The step of introducing a fluid includes opening the valve 61 to inject a gas into the space 15 of the working electrode 10, thereby increasing the pressure of the gas in the space 15 above atmospheric pressure. The step of sealing the end 14 of the working electrode 10 includes closing the valve 61.

[0065] With this configuration, gas at a pressure higher than atmospheric pressure can be easily injected into the space 15 of the working electrode 10 .

[0066] In the above-described embodiment, the working electrode 10 is formed in a tubular shape, and one end 13 of the working electrode 10 is sealed with a sealant and the other end 14 is sealed with a valve 61. However, the present invention is not limited to this. The working electrode 10 may have any shape as long as it has a space that can seal a fluid. The working electrode 10 may be, for example, a cylindrical container with a bottom or a container provided with a hole for introducing a fluid.

[0067] In the above-described embodiment, the exposed portion 11 has a circular shape in plan view, but the shape is not limited to this. The exposed portion 11 may have an elliptical or polygonal shape in plan view.

[0068] Furthermore, in the above-described embodiment, an example has been described in which the fluid contained in the space 15 of the working electrode 10 is a gas, but this is not limiting. The fluid contained in the space 15 of the working electrode 10 may be a liquid. When the fluid contained in the space 15 is a liquid, the liquid can be vaporized to create a state in which a gas with a pressure higher than atmospheric pressure is sealed inside the space 15.

[0069] In the above-described embodiment, an example in which a gas is sealed in the space 15 of the working electrode 10 has been described, but the present invention is not limited to this. For example, a substance in a mixed state of gas and liquid may be sealed in the space 15 of the working electrode 10.

[0070] (Embodiment 2) A second embodiment will be described with reference to Figures 11 to 13. In the second embodiment, the same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. In the second embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0071] FIG. 11 is a diagram schematically illustrating a corrosion sensor 1A according to a second embodiment. FIGS. 12 and 13 are cross-sectional views illustrating a part of a manufacturing process for the corrosion sensor 1A according to the second embodiment. FIGS. 12 and 13 are cross-sectional views of a tube constituting the working electrode 10 cut along a direction intersecting the circumferential direction. As shown in FIG. 11, the second embodiment differs from the first embodiment in that the end 14 of the working electrode 10 is sealed with a heat-melting sealant. Furthermore, as shown in FIGS. 12 and 13, the second embodiment differs from the first embodiment in that the step of introducing gas into the space 15 of the working electrode 10 in step S4 and the step of sealing the end 14 of the working electrode 10 in step S5, both of which are described in the first embodiment.

[0072] 11, the other end 14 of the working electrode 10 is sealed with a heat-melting sealant 51. Examples of the heat-melting sealant 51 include thermoplastic resin and solder. As in the first embodiment, the space 15 of the working electrode 10 is filled with a gas containing, for example, air, nitrogen, helium, or carbon dioxide.

[0073] A method for manufacturing the corrosion sensor 1A will now be described. Steps S1 to S3 in Fig. 4, which were described in the first embodiment, are the same as those in the first embodiment, and therefore will not be described again. In this embodiment, in step S4, compressed gas is injected into the space 15 of the working electrode 10 using the piston 63, and in step S5, one end of the working electrode 10 is sealed with a sealant that melts when heated, thereby manufacturing the corrosion sensor 1A.

[0074] More specifically, in step S4 of FIG. 4, as shown in FIG. 12, compressed gas is injected into the space 15 of the working electrode 10 using a piston 63 from the end 14 of the working electrode 10, so that the pressure of the gas inside the space 15 is made higher than atmospheric pressure. The gas injected by the piston 63 can be, for example, air, nitrogen, helium, or carbon dioxide. At this time, a heat-melting material 52, such as a thermoplastic resin or solder, is placed at one end 14 of the working electrode 10. The material 52 is not melted at the time of step S4, and the one end 14 of the working electrode 10 is not sealed.

[0075] 4, as shown in Fig. 13, the material 52 is melted by a heat source 64 such as a heater and then cooled to form a sealant 51, thereby sealing one end 14 of the working electrode 10. In the example of Fig. 13, the heater 64 is provided at the tip of the piston 63, and the material 52 is melted by the heater 64 to form the sealant 51. The heat source 64 is not limited to the heater 64 provided at the tip of the piston 63, and may be any source that can heat and melt the material 52.

[0076] [effect] According to the above-described embodiment, the following effects can be achieved.

[0077] The step of introducing the gas includes injecting compressed gas into the space 15 of the working electrode 10 from the end 14 of the working electrode 10 using a piston 63, thereby increasing the pressure of the gas in the space 15 above atmospheric pressure. The step of sealing the end 14 includes placing a heat-melting sealant 51 in the space 15 of the working electrode 10, and melting the sealant 51 with a heat source 64 provided at the tip of the piston 63 to seal the end 14 of the working electrode 10.

[0078] With this configuration, the piston 63 can be used to inject gas and seal the end 14, which simplifies the manufacturing process of the corrosion sensor and reduces manufacturing costs.

[0079] (Embodiment 3) Embodiment 3 will be described with reference to Figures 14 to 17. In Embodiment 3, the same or equivalent configurations as in Embodiment 1 will be denoted by the same reference numerals. Also, in Embodiment 3, descriptions that overlap with Embodiment 1 will be omitted.

[0080] FIG. 14 is a diagram schematically illustrating a corrosion sensor 1B according to a third embodiment. FIGS. 15 to 17 are cross-sectional views illustrating a part of a manufacturing process for the corrosion sensor 1B according to the third embodiment. FIGS. 15 to 17 are cross-sectional views of a tube constituting the working electrode 10 cut along a direction intersecting the circumferential direction. The third embodiment differs from the first embodiment in that, as shown in FIG. 14, both one end 13 and the other end 14 of the working electrode 10 are sealed with a sealant 51. Furthermore, as shown in FIGS. 15 to 17, the third embodiment differs from the first embodiment in that a liquid is introduced instead of a gas in step S4, which is described in the first embodiment and in which a fluid is introduced into the space 15 of the working electrode 10. The third embodiment also differs from the first embodiment in step S5, which is the step of sealing the end 14 of the working electrode 10.

[0081] 14, in this embodiment, one end 13 and the other end 14 of the working electrode 10 are sealed with the same sealing material 50. For example, a metal flare cap or the like can be used as the sealing material 50. Alternatively, a resin cap containing epoxy resin may be used as the sealing material 50.

[0082] A method for manufacturing the corrosion sensor 1B will be described. Steps S1 to S3 in FIG. 4, which were described in the first embodiment, are the same as those in the first embodiment, and therefore will not be described again. In the present embodiment, in step S4, a liquid 65 that becomes a gas at room temperature and normal pressure is introduced from the end 14 of the working electrode. The liquid 65 that becomes a gas at room temperature and normal pressure is a substance that transitions to a gaseous state in an environment, for example, where the temperature is between 5°C and 35°C and atmospheric pressure, and is in a liquid state when introduced into the working electrode 10. Examples of the liquid 65 that becomes a gas at room temperature and normal pressure include liquid nitrogen, a volatile organic solvent, and liquid helium.

[0083] As shown in Fig. 15, liquid 65 that becomes a gas at room temperature and normal pressure is injected into space 15 of working electrode 10, and then the other end 14 of working electrode 10 is sealed in step S5 as shown in Fig. 16. When the other end 14 of working electrode 10 is sealed, liquid 65 gradually evaporates, and space 15 of working electrode 10 is filled with gas as shown in Fig. 17. By adjusting the amount of liquid 65 introduced into working electrode 10, the pressure of the gas filling space 15 can be made higher than atmospheric pressure.

[0084] [effect] According to the above-described embodiment, the following effects can be achieved.

[0085] The step of introducing a fluid includes introducing a liquid that becomes a gas at room temperature and pressure from the end 14 of the working electrode 10 .

[0086] With this configuration, the corrosion sensor can be manufactured by a simpler method.

[0087] The liquid may be liquid nitrogen, a volatile organic solvent, or liquid helium.

[0088] With this configuration, the corrosion sensor can be manufactured by a simpler method.

[0089] [Variations] 18 to 19B are cross-sectional views illustrating a part of the manufacturing process of a corrosion sensor according to a modified example of embodiment 3. FIG. 18 is a flowchart illustrating a manufacturing method of a corrosion sensor according to a modified example of embodiment 3. FIGS. 19A to 19B are cross-sectional views of a tube constituting the working electrode 10 cut along a direction intersecting the circumferential direction. In the flowchart of FIG. 18, steps S11 to S13 are the same as steps S1 to S3 in FIG. 4, and therefore description thereof will be omitted.

[0090] As shown in step S14 of FIG. 18 and FIG. 19A, instead of a liquid that becomes a gas at room temperature and normal pressure, a solid substance 66 that becomes a gas at room temperature and normal pressure may be introduced. An example of the solid substance 66 that becomes a gas at room temperature and normal pressure is dry ice. After the solid substance 66 is placed in the space 15 of the working electrode 10, when the other end 14 of the working electrode 10 is sealed in step S15, the solid substance 66 sublimes and the space 15 of the working electrode 10 is filled with gas. By adjusting the amount of solid substance 66 introduced into the space 15 of the working electrode 10, the pressure of the gas filling the space 15 can be made higher than atmospheric pressure.

[0091] (Fourth embodiment) A fourth embodiment will be described with reference to Figures 20 to 22. In the fourth embodiment, the same or equivalent configurations as those in the third embodiment will be denoted by the same reference numerals. In the fourth embodiment, descriptions that overlap with those in the third embodiment will be omitted.

[0092] 20 to 22 are cross-sectional views illustrating a part of the manufacturing process of the corrosion sensor 1C according to embodiment 4. FIGS. 20 to 22 are cross-sectional views of a tube constituting the working electrode 10 cut along a direction intersecting the circumferential direction. Embodiment 4 differs from embodiment 3 in that in step S4, a plurality of chemical substances that generate gas at a pressure higher than atmospheric pressure through a chemical reaction are introduced from end 14 of working electrode 10 into space 15 of working electrode 10.

[0093] In this embodiment, in step S4 of Fig. 4, two types of chemical substances 67 and 68 are introduced into the space 15 of the working electrode 10. The chemical substances 67 and 68 are liquids that undergo a chemical reaction when mixed together to generate a gas. An example of the chemical substances 67 and 68 is a combination of potassium permanganate and hydrogen peroxide.

[0094] As shown in FIG. 20 , in step S4, chemical substances 67 and 68 are sequentially introduced into space 15 of working electrode 10. After introducing chemical substances 67 and 68 into space 15 of working electrode 10, when the other end 14 of working electrode 10 is sealed, a chemical reaction generates gas inside space 15. When chemical substances 67 and 68 are a combination of potassium permanganate and hydrogen peroxide, mixing the two chemical substances generates oxygen through an oxidation-reduction reaction. When the other end 14 of working electrode 10 is sealed, gas is generated from chemical substance 69, which is a mixture of two chemical substances 67 and 68, as shown in FIG. 21 . When the chemical reaction is completed, space 15 is filled with gas, as shown in FIG. 22 . At this time, residue 70 may be generated inside space 15.

[0095] [effect] According to the above-described embodiment, the following effects can be achieved.

[0096] The step of introducing a fluid includes introducing a plurality of chemical substances that generate a gas at a pressure higher than atmospheric pressure through a chemical reaction into the space 15 of the working electrode 10 from the end of the working electrode 10 .

[0097] With this configuration, for example, multiple chemical substances can be prevented from coming into contact with each other inside the space 15 of the working electrode 10, and the multiple chemical substances can be mixed at any time, such as immediately before using the corrosion sensor, to generate gas.

[0098] Some chemicals include potassium permanganate and hydrogen peroxide.

[0099] With this configuration, gas can be generated efficiently.

[0100] (Embodiment 5) 23 to 27, a fifth embodiment will be described. In the fifth embodiment, the same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. In the fifth embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0101] FIG. 23 is a diagram schematically illustrating a corrosion sensor 1D according to a fifth embodiment. FIG. 24 is a flowchart illustrating a method for manufacturing the corrosion sensor 1D of FIG. 23. FIGS. 25 to 27 are cross-sectional views illustrating a portion of the manufacturing process for the corrosion sensor 1D of FIG. 23. FIGS. 25 to 27 are cross-sectional views of a tube constituting the working electrode 10 cut along a direction intersecting the circumferential direction. The fifth embodiment differs from the first embodiment in that a liquid, instead of a gas, is introduced into the space 15 of the working electrode 10. The fifth embodiment differs from the first embodiment in that, as shown in FIG. 23, the other end 14 of the working electrode 10 is sealed with a conductive member 53. Furthermore, the fifth embodiment differs from the first embodiment in that, as shown in FIG. 24, in the manufacturing process for the corrosion sensor 1D, gas is generated in the space 15 by electrolysis after sealing the end 14 of the working electrode 10.

[0102] 23 , in this embodiment, the other end 14 of the working electrode 10 is sealed with a conductive member 53. In this embodiment, as will be described later, a liquid introduced into the space 15 of the working electrode 10 is electrolyzed using the conductive member 53 and the working electrode 10 as electrodes, thereby generating gas inside the space 15. If necessary, the conductive member 53 may be covered with an insulating material such as an insulating seal.

[0103] A method for manufacturing the corrosion sensor 1D will now be described. In the flowchart of Fig. 24, steps S21 to S23 are the same as steps S1 to S3 described in the first embodiment, and therefore a description thereof will be omitted.

[0104] In step S24, the electrolyte 71 is injected into the space 15 from the end of the working electrode 10. As the electrolyte 71, for example, an acidic aqueous solution, an alkaline aqueous solution, an ionic liquid, or the like can be used.

[0105] Next, in step S25, the other end 14 of the working electrode 10 is sealed. The other end 14 of the working electrode 10 is sealed with a conductive member 53 so that it can be used as an electrode during electrolysis.

[0106] Next, in step S26, electrolysis of the electrolytic solution 71 generates gas in the space 15 at a pressure higher than atmospheric pressure. Electrolysis can be performed, for example, by using the metal constituting the working electrode 10 and the conductive member 53 as electrodes and applying a voltage to the electrolytic solution 71 via the electrodes. As shown in FIGS. 25 and 26 , wiring is provided so that the working electrode 10 and the conductive member 53 are electrically connected via a switch 72, and a voltage is applied by a power source 73 when the switch 72 is ON, thereby performing electrolysis.

[0107] Gas is generated by electrolysis, and the space 15 of the working electrode 10 is filled with the gas, as shown in FIG.

[0108] [effect] According to the above-described embodiment, the following effects can be achieved.

[0109] The step of introducing a fluid includes injecting the electrolyte 71 from the end 14 of the working electrode 10. The method for manufacturing a corrosion sensor further includes, after the step of sealing the end 14 of the working electrode 10, a step of generating a gas in the space 15 at a pressure higher than atmospheric pressure by electrolysis of the electrolyte 71.

[0110] With this configuration, gas can be generated by electrolysis at any timing, such as immediately before the corrosion sensor is used.

[0111] The electrolytic solution 71 is composed of an acidic aqueous solution, an alkaline aqueous solution, or an ionic liquid.

[0112] With this configuration, gas can be generated by electrolysis immediately before the corrosion sensor is used.

[0113] (Addendum) The above description of the embodiments discloses the following techniques.

[0114] (Technology 1) A corrosion sensor comprising: a working electrode formed of metal and having a space that seals a fluid; an insulating layer that is placed on the surface of the working electrode so as to expose an exposed portion that is a part of the surface of the working electrode; and a counter electrode that is placed on the insulating layer and has a potential more noble than that of the working electrode.

[0115] This configuration provides a corrosion sensor that can detect corrosion penetration with greater accuracy. By providing a space in which a fluid is sealed in the working electrode, it is possible to accurately detect corrosion penetration from the disturbance in the background current caused by leakage of the fluid inside the working electrode.

[0116] (Technology 2) The corrosion sensor according to Art 1, wherein the fluid contains a gas, and the pressure of the gas in the space of the working electrode is higher than atmospheric pressure.

[0117] With this configuration, the corrosion penetration state can be detected with higher accuracy.

[0118] (Technology 3) 3. The corrosion sensor according to claim 1, wherein the working electrode is made of copper, a phosphorus copper alloy, aluminum, an aluminum manganese alloy, or an aluminum zinc alloy.

[0119] With this configuration, it is possible to provide a corrosion sensor that can detect corrosion currents of various metals.

[0120] (Technology 4) 4. The corrosion sensor according to any one of claims 1 to 3, wherein the working electrode is formed in a tubular shape with both ends sealed.

[0121] With this configuration, it is possible to easily inject a fluid into the space inside the working electrode.

[0122] (Technology 5) 5. The corrosion sensor according to claim 4, wherein the working electrode has a U-shaped bent portion.

[0123] With this configuration, it is possible to detect partial corrosion currents where residual stress exists, and therefore it is possible to detect stress corrosion cracking.

[0124] (Technology 6) 6. The corrosion sensor according to claim 4 or 5, wherein both ends of the working electrode are sealed with resin.

[0125] With this configuration, both ends of the working electrode can be easily sealed.

[0126] (Technology 7) 7. The corrosion sensor according to any one of claims 1 to 6, wherein the insulating layer is made of epoxy resin.

[0127] With this configuration, the working electrode and the counter electrode can be reliably insulated from each other when no liquid is attached to the exposed portion.

[0128] (Technology 8) 8. The corrosion sensor according to any one of claims 1 to 7, wherein the insulating layer is formed to a thickness of 10 μm or more and 500 μm or less.

[0129] With this configuration, it is possible to supply oxygen to the liquid film formed on the surface of the working electrode while maintaining insulation between the working electrode and the counter electrode when no liquid is held in the exposed portion, thereby enabling more efficient detection of corrosion current.

[0130] (Technology 9) 9. The corrosion sensor according to any one of claims 1 to 8, wherein the counter electrode is made of silver or conductive carbon.

[0131] With this configuration, the counter electrode can be easily formed.

[0132] (Technology 10) 10. The corrosion sensor according to any one of claims 1 to 9, wherein the fluid comprises air, nitrogen, helium, carbon dioxide, liquid nitrogen, or a volatile organic solvent.

[0133] With this configuration, the corrosion penetration state can be detected with higher accuracy.

[0134] (Technology 11) 11. The corrosion sensor according to any one of claims 1 to 10, wherein a corrosion current flows between the working electrode and the counter electrode via a liquid adhering to the exposed portion.

[0135] With this configuration, it is possible to provide a corrosion sensor that can detect corrosion penetration with higher accuracy.

[0136] (Technology 12) The corrosion sensor according to any one of the preceding claims, further comprising an ammeter for detecting a corrosion current.

[0137] With this configuration, the corrosion current flowing between the working electrode and the counter electrode can be measured.

[0138] (Technology 13) A method for manufacturing a corrosion sensor, comprising the steps of: preparing a tubular working electrode made of metal; forming an insulating layer on the surface of the working electrode so as to expose an exposed portion that is a part of the surface of the working electrode; forming a counter electrode having a more noble potential than the working electrode on the surface of the insulating layer; introducing a fluid or solid into a space in the working electrode from an end of the working electrode; and sealing the end of the working electrode.

[0139] With this configuration, it is possible to provide a manufacturing method for a corrosion sensor that can detect corrosion penetration with higher accuracy.

[0140] (Technology 14) A method for manufacturing a corrosion sensor according to technology 13, wherein a valve is provided at an end of the working electrode, and the step of introducing a fluid or solid from the end of the working electrode into the space in the working electrode includes opening the valve to inject a gas into the space in the working electrode to increase the pressure of the gas in the space above atmospheric pressure, and the step of sealing the end of the working electrode includes closing the valve.

[0141] With this configuration, gas at a pressure higher than atmospheric pressure can be easily injected into the space 15 of the working electrode.

[0142] (Technology 15) The method for manufacturing a corrosion sensor described in Technology 13, wherein the step of introducing a fluid or solid into the space in the working electrode from the end of the working electrode includes injecting compressed gas into the space in the working electrode from the end of the working electrode using a piston to increase the pressure of the gas in the space above atmospheric pressure, and the step of sealing the end of the working electrode includes arranging a heat-melting sealant in the space in the working electrode and melting the sealant with a heat source provided at the tip of the piston to seal the end of the working electrode.

[0143] With this configuration, the piston can be used to inject gas and seal the end, which simplifies the manufacturing process of the corrosion sensor and reduces manufacturing costs.

[0144] (Technology 16) The method for manufacturing a corrosion sensor according to claim 13, wherein the step of introducing a fluid or a solid into the space of the working electrode from the other end of the working electrode includes introducing a liquid or solid substance that becomes a gas at room temperature and normal pressure from the end of the working electrode.

[0145] With this configuration, the corrosion sensor can be manufactured by a simpler method.

[0146] (Technology 17) 17. The method for manufacturing a corrosion sensor according to claim 16, wherein the liquid or solid substance is liquid nitrogen, a volatile organic solvent, liquid helium, or dry ice.

[0147] With this configuration, the corrosion sensor can be manufactured by a simpler method.

[0148] (Technology 18) The method for manufacturing a corrosion sensor according to Technology 13, wherein the step of introducing a fluid or solid into the space of the working electrode from the other end of the working electrode includes injecting an electrolyte from the end of the working electrode, and the method further includes, after the step of sealing the end of the working electrode, a step of generating a gas with a pressure higher than atmospheric pressure in the space by electrolysis of the electrolyte.

[0149] With this configuration, gas can be generated by electrolysis at any timing, such as immediately before the corrosion sensor is used.

[0150] (Technology 19) 19. The method for manufacturing a corrosion sensor according to claim 18, wherein the electrolyte is an acidic aqueous solution, an alkaline aqueous solution, or an ionic liquid.

[0151] With this configuration, gas can be generated by electrolysis immediately before the corrosion sensor is used.

[0152] (Technology 20) The method for manufacturing a corrosion sensor described in Technology 13, wherein the step of introducing a fluid or a solid from the end of the working electrode into the space of the working electrode includes introducing a plurality of chemical substances that generate a gas at a pressure higher than atmospheric pressure through a chemical reaction from the end of the working electrode into the space of the working electrode.

[0153] With this configuration, for example, multiple chemical substances can be prevented from coming into contact with each other inside the space of the working electrode, and the multiple chemical substances can be mixed at any time, such as immediately before using the corrosion sensor, to generate gas.

[0154] (Technology 21) 20. The method for manufacturing a corrosion sensor according to claim 20, wherein the plurality of chemicals includes potassium permanganate and hydrogen peroxide.

[0155] With this configuration, gas can be generated efficiently. [Industrial Applicability]

[0156] The present disclosure is useful in detecting corrosion currents in metals. [Explanation of symbols]

[0157] 1, 1A, 1B, 1C, 1D Corrosion Sensors 10 Working electrode 11 Exposed part 12 Bend section 13 End 14 End 15 Space 20 insulating layer 21 Space 30 Opposite 40 ammeter 50, 51 Encapsulating material 61 Valve 62 Gas Cylinder 63 Piston 64 Heat source

Claims

1. a working electrode formed of metal and having a space that seals a fluid; an insulating layer disposed on the surface of the working electrode so as to expose an exposed portion that is a part of the surface of the working electrode; a counter electrode disposed on the insulating layer and having a more noble potential than the working electrode; Equipped with Corrosion sensors.

2. the pressure of the fluid in the space of the working electrode is higher than atmospheric pressure; The corrosion sensor according to claim 1 .

3. The working electrode is formed of copper, a phosphorus copper alloy, aluminum, an aluminum manganese alloy, or an aluminum zinc alloy. The corrosion sensor according to claim 1 .

4. The working electrode is formed in a tubular shape with both ends sealed. The corrosion sensor according to claim 1 .

5. The working electrode has a U-shaped bent portion. The corrosion sensor according to claim 4 .

6. Both ends of the working electrode are sealed with resin. The corrosion sensor according to claim 4 .

7. The insulating layer is made of epoxy resin. The corrosion sensor according to claim 1 .

8. The insulating layer is formed to a thickness of 10 μm or more and 500 μm or less. The corrosion sensor according to claim 1 .

9. The counter electrode is made of silver or conductive carbon. The corrosion sensor according to claim 1 .

10. The fluid comprises air, nitrogen, helium, carbon dioxide, liquid nitrogen, or a volatile organic solvent. The corrosion sensor according to claim 1 .

11. a corrosion current flows between the working electrode and the counter electrode via the liquid adhering to the exposed portion; The corrosion sensor according to any one of claims 1 to 10.

12. Further, an ammeter for detecting the corrosion current is provided. The corrosion sensor according to claim 11.

13. preparing a tubular working electrode made of metal; forming an insulating layer on the surface of the working electrode so as to expose an exposed portion that is a part of the surface of the working electrode; forming a counter electrode having a more noble potential than the working electrode on a surface of the insulating layer; introducing a fluid or a solid into a space of the working electrode from an end of the working electrode; sealing an end of the working electrode; Including, A method for manufacturing a corrosion sensor.

14. a valve is provided at the end of the working electrode; The step of introducing a fluid or a solid into the space of the working electrode from the end of the working electrode includes: opening the valve to inject gas into the space around the working electrode to increase the pressure of the gas in the space above atmospheric pressure; The step of sealing the end of the working electrode includes: closing the valve. A method for manufacturing the corrosion sensor according to claim 13.

15. The step of introducing a fluid or a solid into the space of the working electrode from the end of the working electrode includes: a compressed gas is injected into a space in the working electrode from an end of the working electrode using a piston, thereby increasing the pressure of the gas in the space above atmospheric pressure; The step of sealing the end of the working electrode includes: and disposing a heat-melting sealant in the space of the working electrode, and melting the sealant with a heat source provided at the tip of the piston to seal the end of the working electrode. A method for manufacturing the corrosion sensor according to claim 13.

16. The step of introducing a fluid or a solid into the space of the working electrode from the other end of the working electrode includes: introducing a liquid or solid substance that becomes a gas at room temperature and normal pressure from the end of the working electrode; A method for manufacturing the corrosion sensor according to claim 13.

17. The liquid or solid substance is liquid nitrogen, a volatile organic solvent, liquid helium, or dry ice. A method for manufacturing the corrosion sensor according to claim 16.

18. The step of introducing a fluid or a solid into the space of the working electrode from the other end of the working electrode includes: injecting an electrolyte solution from an end of the working electrode; The method further comprises: a step of generating a gas having a pressure higher than atmospheric pressure in the space by electrolysis of the electrolyte after the step of sealing the end of the working electrode; A method for manufacturing the corrosion sensor according to claim 13.

19. The electrolyte solution is composed of an acidic aqueous solution, an alkaline aqueous solution, or an ionic liquid. A method for manufacturing the corrosion sensor according to claim 18.

20. The step of introducing a fluid or a solid into the space of the working electrode from the end of the working electrode includes: introducing a plurality of chemical substances that generate a gas having a pressure higher than atmospheric pressure through a chemical reaction from an end of the working electrode into a space of the working electrode; A method for manufacturing the corrosion sensor according to claim 13.

21. the plurality of chemicals including potassium permanganate and hydrogen peroxide; A method for manufacturing the corrosion sensor according to claim 20.

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