Hydrogen penetration amount measurement device, hydrogen penetration amount measurement kit, and hydrogen penetration amount measurement method

Abstract

To provide a hydrogen penetration amount measurement device, a hydrogen penetration amount measurement kit, and a hydrogen penetration amount measurement method which measure the amount of hydrogen penetration into the inside of a metal material according to corrosion of the metal material even in an environment with temperature fluctuation with high accuracy.SOLUTION: A hydrogen penetration amount measurement device for measuring the amount of hydrogen penetrating into the inside of a metal material due to corrosion by an electrochemical hydrogen permeation method includes: a temperature sensor installed on a surface of the metal material; and a plurality of electrochemical cells installed on one surface of the metal material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus for measuring the amount of hydrogen that has penetrated into a metal material due to corrosion by an electrochemical hydrogen permeation method, and a kit for measuring the amount of hydrogen that has penetrated.

Background Art

[0002] In recent years, from the viewpoints of energy conservation and resource conservation, the strength of steel materials used in industrial fields has been increasing. The steel sheets used in automobiles are also being strengthened, and the application of high-strength steel sheets with a tensile strength exceeding 1180 MPa is also being promoted.

[0003] However, as one of the problems of high-strength steel materials, the occurrence of "delayed fracture" is known. For example, it is often reported that high-tensile bolts break in the use environment, and this breakage is caused by delayed fracture.

[0004] Delayed fracture is a phenomenon in which a metal material, when subjected to a static load stress (a load stress below the tensile strength), suddenly undergoes brittle fracture with almost no plastic deformation after a certain period of time. Delayed fracture is more likely to occur, for example, in the case of a metal material being a steel material, as the strength of the steel material increases. In particular, it is known that delayed fracture is likely to occur in high-strength steel materials with a tensile strength of 1180 MPa or more.

[0005] It is known that delayed fracture occurring in steel materials is caused by residual stress when the steel material is formed into a predetermined shape by processing such as press working, and hydrogen embrittlement of the steel material at the concentration part of the residual stress.

[0006] In most cases, the hydrogen that causes the above hydrogen embrittlement is hydrogen that has penetrated into the steel material from the external environment and diffused (penetrated hydrogen). And it has been reported that the more the amount of penetrated hydrogen in the steel material, the more likely delayed fracture occurs. Therefore, in order to evaluate the delayed fracture characteristics of steel materials, it is important to evaluate the amount of penetrated hydrogen with high accuracy.

[0007] Here, the hydrogen that penetrates into the steel from the external environment is mainly the hydrogen generated along with the corrosion of the steel. However, since the amount of hydrogen that penetrates into the steel along with the corrosion of the steel is extremely small, various techniques for measuring such a small amount of infiltrated hydrogen have been proposed.

[0008] For example, Non-Patent Document 1 reports a method of continuously measuring, as an anodic current, the hydrogen that has penetrated from the surface of a steel plate exposed to an atmospheric corrosion environment to the opposite side (detection surface) of the steel plate by the electrochemical hydrogen permeation method.

[0009] However, the anodic current measured by the electrochemical hydrogen permeation method includes, in addition to the hydrogen permeation current measured when hydrogen atoms that have penetrated through the steel plate are ionized at the detection surface, the passivation holding current of the metal formed on the detection surface side. Although it is known that the passivation holding current depends on temperature (Non-Patent Document 2), in the method described in Non-Patent Document 1, the temperature dependence is not considered, so the amount of infiltrated hydrogen cannot be accurately evaluated.

[0010] Therefore, in Patent Document 1, a method for correcting the influence of the passivation holding current in the measurement of the amount of infiltrated hydrogen by the electrochemical hydrogen permeation method has been proposed. Specifically, two or more measurement cells are installed for the same test piece, and a protective film is provided on the hydrogen infiltration surface of one of the measurement cells to prevent the infiltration of hydrogen, thereby serving as a reference cell for measuring the passivation holding current. By subtracting the passivation holding current measured by the reference cell from the anodic current measured by the normal measurement cell, the influence of the passivation holding current that varies with temperature is removed.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Non-Patent Documents

[0012]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0013] According to the method described in Patent Document 1, it is possible to improve the measurement accuracy of the amount of hydrogen entering the interior of a steel material in an atmospheric corrosion environment. However, as a result of the study by the present inventors, it was found that there is still room for further improvement in the measurement accuracy in an environment with temperature fluctuations.

[0014] The present invention has been made in view of such circumstances, and an object thereof is to provide an amount-of-intruded-hydrogen measuring device and an amount-of-intruded-hydrogen measuring kit capable of measuring the amount of hydrogen intruding into the interior of a metal material with higher accuracy in an environment with temperature fluctuations as the metal material corrodes.

Means for Solving the Problems

[0015] As a result of investigations conducted to solve the above problems, the present inventors obtained the following findings.

[0016] (1) As described above, the hydrogen that intrudes into the interior of a metal material is mainly hydrogen generated accompanying the corrosion of the metal material. Therefore, it is common to measure the amount of hydrogen intrusion into the metal material over a long period while the metal material is exposed to a corrosion environment. And in such a corrosion environment, the temperature of the metal material as the test object may vary greatly.

[0017] (2) When calculating the amount of hydrogen intrusion from the measured anode current, the diffusion coefficient of hydrogen in the metal material is used, and this diffusion coefficient depends on temperature. Therefore, when measuring the amount of intruded hydrogen in an environment with large temperature fluctuations, the variation of the diffusion coefficient due to temperature has a non-negligible impact on the measurement accuracy. Therefore, in order to further improve the measurement accuracy, it is necessary to measure the temperature together with the anode current and calculate the amount of intruded hydrogen considering the influence of the temperature.

[0018] (4) As the temperature, it is conceivable to use the temperature of the environment (atmosphere) in which the test object is placed. However, when measuring the amount of intruded hydrogen in an outdoor exposure environment, etc., a large deviation may occur between the temperature of the environment and the temperature of the test object due to the influence of direct sunlight, radiative cooling, etc. Therefore, it is important to install a temperature sensor on the surface of the metal material that is the test object and directly measure the temperature of the test object.

[0019] The present invention has been completed based on the above findings, and the main configuration is as follows.

[0020] 1. An apparatus for measuring the amount of hydrogen intrusion that measures the amount of hydrogen intruding into the interior of a metal material due to corrosion by the electrochemical hydrogen permeation method, comprising: a temperature sensor installed on the surface of the metal material; a plurality of electrochemical cells installed on one surface of the metal material; and an apparatus for measuring the amount of hydrogen intrusion.

[0021] 2. Further comprising a first film layer having insulating properties disposed on the surface of the metal material, and a second film layer having thermal conductivity and electrical conductivity disposed on the first film layer, wherein the temperature sensor is disposed on the second film layer, and the apparatus for measuring the amount of hydrogen intrusion according to 1 above. and a second film layer having thermal conductivity and electrical conductivity disposed on the first film layer, and the temperature sensor is disposed on the second film layer, the apparatus for measuring the amount of hydrogen intrusion according to 1 above. The apparatus for measuring the amount of hydrogen intrusion according to 1 above, wherein the temperature sensor is disposed on the second film layer.

[0022] 3. The apparatus for measuring the amount of hydrogen intrusion according to 2 above, wherein the thickness of the first film layer is 1 to 100 μm.

[0023] 4. The hydrogen ingress amount measuring device according to 2 above, wherein the second film layer is a metal layer made of at least one selected from the group consisting of aluminum, copper, and stainless steel.

[0024] 5. The hydrogen ingress amount measuring device according to 2 above, further comprising a third film layer covering the temperature sensor.

[0025] 6. A hydrogen ingress amount measuring kit for measuring the amount of hydrogen that penetrates into a metal material due to corrosion by an electrochemical hydrogen permeation method, the metal material as a test specimen, a temperature sensor installed on the surface of the metal material, a plurality of electrochemical cells installed on one surface of the metal material, and comprising on the other surface of the metal material, a hydrogen non-invasion part covered by a protective layer that prevents hydrogen invasion and a hydrogen invasion part where the protective layer is not provided are formed, one of the plurality of electrochemical cells is arranged on the opposite side of the hydrogen non-invasion part, and the rest of the plurality of electrochemical cells are arranged on the opposite side of the hydrogen invasion part. The hydrogen ingress amount measuring kit.

[0026] 7. Further comprising an insulating first film layer disposed on the surface of the metal material, and a second film layer having thermal conductivity and electrical conductivity disposed on the first film layer, wherein the temperature sensor is disposed on the second film layer. The hydrogen ingress amount measuring kit according to 6 above.

[0027] 8. The hydrogen ingress amount measuring kit according to 7 above, wherein the thickness of the first film layer is 1 to 100 μm.

[0028] 9. The hydrogen ingress amount measuring kit according to 7 above, wherein the second film layer is a metal layer made of at least one selected from the group consisting of aluminum, copper, and stainless steel.

[0029] 10. The hydrogen ingress amount measurement kit according to item 7 above, further comprising a third film layer that coats the temperature sensor.

[0030] 11. A method for measuring the amount of hydrogen that has penetrated into a metal material due to corrosion by means of an electrochemical hydrogen permeation method, a plurality of electrochemical cells are installed on one surface of the metal material as the specimen, one of the plurality of electrochemical cells is used as a reference cell, and the rest are used as cells for measuring the amount of hydrogen ingress, on the other surface of the metal material, a hydrogen non-ingress portion covered with a protective layer that prevents the ingress of hydrogen and a hydrogen ingress portion where the protective layer is not provided are formed, the reference cell is arranged on the opposite side of the hydrogen non-ingress portion, the cells for measuring the amount of hydrogen ingress are arranged on the opposite side of the hydrogen ingress portion, the anodic current value measured by the cells for measuring the amount of hydrogen ingress is corrected using the passive current holding current measured by the reference cell, a temperature sensor is installed on the surface of the metal material to measure the temperature of the metal material, from the temperature of the metal material, the diffusion coefficient of hydrogen in the metal material is determined, a method for measuring the amount of hydrogen ingress, which calculates the amount of hydrogen ingress from the corrected anodic current and the diffusion coefficient.

[0031] 12. An insulating first film layer is arranged on the surface of the metal material, a second film layer having thermal conductivity and conductivity is arranged on the first film layer, the temperature sensor is arranged on the second film layer, and the method for measuring the amount of hydrogen ingress according to item 11 above.

[0032] 13. The method for measuring the amount of hydrogen ingress according to item 12 above, wherein the thickness of the first film layer is 1 to 100 μm.

[0033] 14. The method for measuring the amount of hydrogen ingress according to item 12 above, wherein the second film layer is a metal layer composed of at least one selected from the group consisting of aluminum, copper, and stainless steel.

[0034] 15. The method for measuring the amount of hydrogen intrusion according to item 12 above, further comprising a third film layer covering the temperature sensor.

Advantages of the Invention

[0035] According to the present invention, even in an environment with temperature fluctuations, the amount of hydrogen intrusion that penetrates into the interior of a metal material due to corrosion of the metal material can be accurately measured.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0037] Hereinafter, the present invention will be described with reference to the drawings. In each figure, corresponding parts are denoted by the same reference numerals. Note that the following description is about examples of preferred embodiments of the present invention, and the present invention is not limited to the embodiments described below. Also, regarding points not particularly mentioned, it can be the same as the disclosure of Patent Document 1 above.

[0038] (First Embodiment) FIG. 1 is a schematic diagram showing the structure of the hydrogen ingress amount measuring device 1 and the hydrogen ingress amount measuring kit 50 in the first embodiment of the present invention. In this specification, the hydrogen ingress amount measuring kit 50 is a state in which an electrochemical cell etc. necessary for measurement is attached to a metal material 51 as a test specimen, the part excluding the metal material from the hydrogen ingress amount measuring kit 50 is the hydrogen ingress amount measuring device 1, and the one obtained by applying an electrochemical measurement power supply PS to the hydrogen ingress amount measuring kit 50 is called a hydrogen ingress amount measuring system 100.

[0039] The hydrogen ingress amount measuring device 1 includes a temperature sensor 20 installed on the surface of the metal material 51 and a plurality of electrochemical cells 2 installed on one surface (the lower surface in FIG. 1) of the metal material 51. Further, the hydrogen ingress amount measuring kit 50 includes a metal material 51 as a test specimen, a temperature sensor 20 installed on the surface of the metal material 51, and a plurality of electrochemical cells 2 installed on one surface (the lower surface in FIG. 1) of the metal material 51.

[0040] Details of each part will be described below.

[0041] [Metal Material] The measuring device and the measuring kit of the present invention are for measuring the amount of hydrogen that penetrates into the interior of a metal material due to corrosion by the electrochemical hydrogen permeation method. That is, a metal material is used as the test specimen. As the metal material, any metal material can be used without particular limitation, but usually, a material in which delayed fracture occurs may be used. Examples of materials in which delayed fracture occurs include steel, aluminum alloy, and nickel alloy. The steel may be, for example, carbon steel or stainless steel.

[0042] As described above, generally, the higher the strength of the steel material, the more likely delayed fracture is to occur. Therefore, when using a steel material as the metal material, it is preferable to use a high-strength steel having a high tensile strength as the steel material, and among them, it is preferable to use a high-strength steel having a tensile strength of 1180 MPa or more.

[0043] The metal material may have a coating on at least a part of its surface. When the metal material is in a plate shape, it may have a coating on at least one of its surfaces. The coating is not particularly limited, and any coating can be used. The coating may be a coating made of metal, a coating made of non-metal, or a coating made of both metal and non-metal. Examples of the non-metal include resin, ceramics, carbon, and the like. The coating may be a plating layer or a coating film. Further, the coating may be a multilayer coating composed of a plurality of layers of the same or different types.

[0044] In addition, when the coating hinders the measurement, the coating existing at the position where the electrochemical cell is installed may be removed in advance, and then the electrochemical cell may be installed.

[0045] As shown in FIG. 1, an electrochemical cell 2 is installed on one surface of a metal material 51, and electrochemical measurement using the electrochemical cell 2 is performed. Among one surface of the metal material 51, the portion where the electrochemical cell 2 is attached preferably includes a layer made of a metal (hereinafter referred to as a metal layer) having a large hydrogen diffusion constant and promoting the oxidation reaction of hydrogen. Examples of the metal constituting the metal layer include Pd, Pd alloys, and Ni. Examples of the Pd alloy include Pd-Ni alloy and Pd-Co alloy.

[0046] By coating these metals, the oxidation reaction of the intruded hydrogen is promoted, so that the sensitivity of the anodic current due to the ionization of hydrogen can be increased. Also, one of the electrochemical cells is used as a reference cell, and by providing the metal layer, the passive holding current in the reference cell can also be reduced. Note that Pd has a larger hydrogen diffusion constant than Ni and also has a high effect of reducing the temperature dependence of the passive holding current. Therefore, it is more preferable to use a Pd coating as the metal layer.

[0047] In the case where the above-described coating exists on the surface of the metal material, it is preferable to remove the coating existing at the position where the electrochemical cell is installed to expose the surface of the metal material, and then form the metal layer at the position.

[0048] The thickness of the metal layer is not particularly limited, but is preferably 10 to 100 nm.

[0049] The metal layer is preferably an electroplated film formed by electroplating.

[0050] When forming an electroplated film of Pd or a Pd alloy as the metal layer, cathodic electrolysis may be performed in an aqueous solution (electroplating bath) containing palladium ions. As the palladium ion source in the electroplating bath, for example, palladium compounds such as [Pd(NH 3 ) 4 Cl 2 ·H 2 O can be used. Also, when forming a Ni electroplated film, cathodic electrolysis may be performed in an arbitrary electroplating bath such as a Watts bath.

[0051] The metal layer may be a coating composed of a plurality of layers. For example, a Ni electroplated film formed on the surface of a metal material and a Pd electroplated film or a Pd alloy electroplated film formed on the Ni electroplated film can also be used.

[0052] The shape of the metal material as the specimen is not particularly limited, and it may have any shape as long as it has one surface for attaching the electrochemical cell and the other surface through which hydrogen enters due to corrosion. Typically, it is preferable to use a plate-shaped metal material as shown in FIG. 1 as the specimen.

[0053] The thickness of the metal material is not particularly limited. However, if the metal material is excessively thick, the time lag between changes in the corrosion environment and changes in the measured hydrogen permeation current increases. As a result, the relationship between environmental factors and the amount of hydrogen intrusion may become unclear. Also, when the hydrogen diffusion coefficient in the metal material is small, it is better to make the metal material 51 thinner. Furthermore, from the perspective that accurate calculation of the amount of hydrogen intrusion cannot be performed if hydrogen diffusion in the metal material is non-steady, the metal material should be thinner. Therefore, the thickness of the metal material is preferably 1 mm or less, and more preferably 0.5 mm or less. On the other hand, if the metal material is excessively thin, pitting due to corrosion occurs in a short period, and measurement cannot be continued. Therefore, the thickness of the metal material is preferably 0.2 mm or more.

[0054] (Hydrogen non-intrusion part) The hydrogen intrusion amount measuring device of the present invention includes a plurality of electrochemical cells, one of which can be used as a reference cell and the other cells can be used as cells for measuring the hydrogen intrusion amount. By measuring the passive current holding current in the reference cell and subtracting the passive current holding current from the current measured in the cell for measuring the hydrogen intrusion amount, it becomes possible to monitor the hydrogen intrusion amount without being affected by the temperature dependence of the passive current holding current.

[0055] In order to measure the passive current holding current by such a reference cell in this way, it is necessary to provide a hydrogen non-intrusion part 53 covered with a protective layer 52 that prevents hydrogen intrusion on a part of the other surface of the metal material 51. In the hydrogen non-intrusion part 53, since the protective layer 52 exists, the metal material 51 is not directly exposed to the corrosion environment. Therefore, in the electrochemical cell 2a arranged on the opposite side of the hydrogen non-intrusion part, that is, in the reference cell, the current caused by the intruding hydrogen is not measured, and only the passive current holding current is measured.

[0056] In addition, if the area of the hydrogen non-invasion part 53 is excessively small, the current measured by the reference cell may include a component caused by the invasive hydrogen. Therefore, the area of the hydrogen non-invasion part 53 is preferably larger than the measurement area of the electrochemical cell 2a (reference cell) arranged on the opposite surface of the hydrogen non-invasion part. Here, the area of the hydrogen non-invasion part 53 is the area covered by the protective layer 52. Also, the measurement area of the electrochemical cell 2a is the area of the part of the surface of the metal material 51 that is in contact with the electrolytic solution 4 in the electrolytic cell 3 of the electrochemical cell 2a. Usually, the measurement area is equal to the area of the opening of the electrolytic cell 3 of the electrochemical cell 2a.

[0057] The protective layer 52 is not particularly limited as long as it can block the corrosive environment, and any layer can be used. As the protective layer 52, for example, it is preferable to use one or both of a metal layer and an organic layer. Examples of the material of the metal layer include aluminum, stainless steel, copper, etc. The metal layer may be a metal foil, and among them, aluminum foil, stainless steel foil, copper foil, etc. can be preferably used. Also, the organic layer may typically be a resin layer, and for example, it is preferable to use a resin film, a resin coating film, etc. As the resin film, it is preferable to use a polyester film, and more preferably to use a polyethylene terephthalate (PET) film. As the resin coating film, for example, a coating film formed by anticorrosive coating can be used. The protective layer 52 may be a single layer or a multilayer composed of the same or different multiple layers.

[0058] The protective layer 52 may be attached to the surface of the metal material 51 using an organic adhesive (adhesive layer), an adhesive tape, etc. Also, it is preferable to use a tape with an adhesive pre-coated on the surface of the metal foil or the resin film as the protective layer 52. As the tape, a tape having a resin film as a base material (support) and a metal layer provided on the surface of the resin film can also be used. The metal layer may be, for example, a vapor deposition layer obtained by vapor depositing a metal on the surface of the resin film.

[0059] (Hydrogen Ingress Port) On the other hand, among the other surfaces of the metal material 51, the portion where the protective layer 52 is not provided functions as a hydrogen ingress port 54. That is, since the hydrogen ingress port 54 is not protected by the protective layer, it is directly exposed to the corrosive environment. Therefore, corrosion of the metal material 51 progresses on the surface of the hydrogen ingress port 54, and hydrogen atoms (H ad ) generated accordingly penetrate into the metal material 51. The penetrated hydrogen diffuses inside the metal material 51 and reaches the opposite surface of the metal material 51, and is oxidized by the electrochemical cell 2b arranged on the opposite surface of the hydrogen ingress port 54, that is, the cell for measuring the amount of penetrated hydrogen, and is released into the electrolyte as H + , and is detected as an electric current at that time.

[0060] [Coated Wire] When measuring the amount of penetrated hydrogen using the device of the present invention, electrochemical measurement is performed with the metal material 51 as the working electrode. Therefore, when using the device for measuring the amount of penetrated hydrogen of the present invention, it is only necessary to energize the metal material 51 through the coated wire 7. Further, the kit 50 for measuring the amount of penetrated hydrogen of the present invention may include a coated wire 7 for energizing the metal material 51. When performing the measurement, it is only necessary to connect the coated wire 7 to the terminal for the working electrode of the power supply PS for electrochemical measurement.

[0061] The coated wire 7 is not particularly limited, and any one can be used. Typically, the same one as the coated wire 6 connected to the electrode described later can be used.

[0062] [Electrochemical Cell] The device 1 for measuring the amount of penetrated hydrogen and the kit 50 for measuring the amount of penetrated hydrogen of the present invention include a plurality of electrochemical cells 2. One of the plurality of electrochemical cells 2 is used as a reference cell, and the rest are used as cells for measuring the amount of hydrogen ingress.

[0063] The number of the electrochemical cells 2 may be any number of 2 or more. In FIG. 1, the case where the number of the electrochemical cells 2 is 2 is shown as an example, but the number of the electrochemical cells 2 may be 2 or more. In other words, the number of the cells for measuring hydrogen ingress may be 1 or may be 2 or more. When there are a plurality of cells for measuring hydrogen ingress, the amount of hydrogen ingress at a plurality of positions of the metal material 51 can be measured simultaneously. However, if the number of the electrochemical cells 2 is too large, the device structure becomes complicated and the cost increases. Therefore, the number of the electrochemical cells 2 is preferably 10 or less, and more preferably 5 or less.

[0064] Next, the structure of the electrochemical cell 2 will be described. Note that the structures of the reference cell and the cell for measuring hydrogen ingress may be basically the same.

[0065] The structure of the electrochemical cell 2 is not particularly limited, and any structure can be adopted as long as it can perform electrochemical measurement. Typically, the electrochemical cell 2 includes an electrolytic cell and an electrode.

[0066] The electrochemical cell 2 in the embodiment shown in FIG. 1 includes the following components. · An electrolytic cell 3 that holds an electrolytic solution 4 inside so as to contact one surface (the lower surface in FIG. 1) of the metal material 51 · An electrode 5 provided to penetrate the electrolytic cell 3 such that one end is inside the electrolytic cell 3 and the other end is located outside the electrolytic cell 3 · A covering wire 6 connected to the other end of the electrode 5

[0067] Hereinafter, each component of the electrochemical cell 2 in the embodiment shown in FIG. 1 will be described.

[0068] (Electrolytic cell) The electrochemical cell 2 includes an electrolytic cell 3. As the electrolytic cell 3, any one can be used as long as it can accommodate the electrolytic solution 4 and can bring the electrolytic solution 4 into contact with the surface of the metal material 51. Typically, as shown in FIG. 1, the electrolytic cell 3 includes an opening for bringing the electrolytic solution 4 into contact with the metal material 51.

[0069] The material of the electrolytic cell 3 is not particularly limited, but from the viewpoints of durability, workability, ease of operation, chemical resistance to the electrolytic solution, etc., it is preferably made of resin. Further, from the viewpoint of being able to visually confirm the state of the electrolytic solution in the electrolytic cell 3, the electrolytic cell 3 is preferably transparent. From the above viewpoints, the electrolytic cell 3 is more preferably made of acrylic resin.

[0070] The size of the electrolytic cell 3 is not particularly limited, but it is preferable to unify the size of the electrolytic cell 3 so that the measurement areas in each electrochemical cell 2 are equal. Here, the measurement area is the area of the portion where the electrolytic solution 4 contacts the metal material 51. Usually, the area of the opening of the electrolytic cell 3 can be regarded as the measurement area.

[0071] (Electrolytic solution) The electrolytic solution 4 is not particularly limited, and any electrolytic solution can be used. From the viewpoint of maintaining the surface of the metal material 51 in a passive state during measurement, it is preferable that the pH of the electrolytic solution 4 is 9 or more. On the other hand, if it is strongly alkaline with a pH higher than 13, when it leaks due to an accident, the damage to the environment is large. Therefore, the pH of the electrolytic solution 4 is preferably 13 or less.

[0072] The composition of the electrolytic solution is not particularly limited and may be any composition. From the viewpoint of ensuring the passivation state of the surface of the metal material 51, for example, an aqueous NaOH solution of about 0.1 to 0.5 M (M = mol / L) is preferably used.

[0073] The electrolytic solution may be in a liquid state, but from the viewpoints of preventing leakage of the electrolytic solution and ease of handling, it is also preferable to use a gel-like electrolyte. In order to make the electrolytic solution gel-like, an arbitrary gelling agent may be added to the electrolytic solution.

[0074] (Electrode) Each electrochemical cell 2 includes at least one electrode 5. When measuring the amount of hydrogen intrusion in a two-electrode configuration, it is sufficient for the electrochemical cell 2 to have one electrode 5. In this case, the metal material 51 serves as the working electrode, and the electrode 5 of the electrochemical cell 2 serves as the counter electrode.

[0075] However, from the perspective of more accurately controlling the potential of the metal material 51, it is preferable to use a three-electrode configuration rather than a two-electrode configuration. When measuring the amount of hydrogen intrusion in a three-electrode configuration, as shown in FIG. 1, it is sufficient for the electrochemical cell 2 to have two electrodes 5c and 5r. In this case, the metal material 51 serves as the working electrode, the electrode 5c serves as the counter electrode, and the electrode 5r serves as the reference electrode.

[0076] · Counter electrode The material of the electrode 5c used as the counter electrode is not particularly limited as long as it enables measurement of the anodic current, but typically it is preferable to use a metal electrode. The metal is not particularly limited, but it is preferable to use an inert metal so as not to inhibit the ionization reaction of hydrogen atoms. Examples of the inert metal include platinum, gold, ruthenium, rhodium, palladium, iridium, and their alloys. Among them, platinum and gold are very stable in the electrolyte and have high conductivity, so they are preferably used as the counter electrode. It is also possible to use an electrode in which the inert metal is plated on the surface of a substrate such as titanium.

[0077] · Reference electrode The reference electrode is an electrode that serves as a potential reference when measuring the anodic current, and is also referred to as a reference electrode. The material of the electrode 5r used as the reference electrode is not particularly limited, but typically it is preferable to use a metal electrode, and more preferably it is iridium (Ir) or tungsten (W). This is because Ir and W form an oxide film on the surface in the electrolyte and can obtain a stable potential over a long period. It is also possible to use an electrode in which Ir or W is plated on the surface of a substrate such as titanium.

[0078] The shape of the electrode 5 is not particularly limited in either the case of the counter electrode or the reference electrode, and can be any shape. Typically, it is preferably rod-shaped or linear.

[0079] The electrode 5 is installed so as to penetrate the electrolytic cell 3 such that one end thereof is located inside the electrolytic cell 3 and the other end is located outside the electrolytic cell 3.

[0080] (Coated wire) The other end of the electrode 5, that is, the end located outside the electrolytic cell 3, is connected to the coated wire 6. The coated wire 6 is for connecting the electrode 5 to the power supply PS for electrochemical measurement.

[0081] The coated wire 6 is not particularly limited, and any wire can be used. Typically, a wire in which a metal wire is coated with an insulating material such as resin can be used as the coated wire 6. The metal wire is preferably a wire made of a metal with low electrical resistance such as silver or copper.

[0082] The connection between the electrode 5 and the coated wire 6 can be made by any method. Typically, soldering can be used. In addition, when the material of the electrode 5 is difficult to solder, another metal that is easy to solder may be interposed between the electrode 5 and the coated wire 6.

[0083] [Temperature sensor] The hydrogen ingress amount measuring device 1 includes a temperature sensor 20 installed on the surface of the metal material 51. Further, the hydrogen ingress amount measuring kit 50 includes a temperature sensor 20 installed on the surface of the metal material 51. The temperature sensor 20 is not particularly limited, and any sensor can be used as long as it can measure the temperature of the metal material 51. From the viewpoints of measurement accuracy, durability, cost, etc., it is preferable to use a thermocouple as the temperature sensor 20. Any thermocouple can be used.

[0084] In addition, generally available thermocouples can be roughly classified into the following three types. (1) Coated thermocouple: A thermocouple in which the thermocouple wire is coated with a flexible insulating material such as resin, glass fiber, or ceramic fiber. The temperature measuring part at the tip is exposed for use. (2) Sheathed thermocouple: A thermocouple in which the thermocouple wire is housed inside a protective tube made of metal or ceramic. (3) Sheath type thermocouple: A thermocouple in which the thermocouple wire is housed inside a sheath (sheathing tube), and the inside of the sheath is filled with insulating powder such as magnesia. The above-mentioned sheathed thermocouple and sheath type thermocouple are larger in size and heavier by the amount of the protective tube or sheath. Therefore, from the viewpoints of miniaturization and weight reduction, it is preferable to use a coated thermocouple.

[0085] When using the hydrogen ingress amount measuring device 1, it is preferable to install the temperature sensor 20 on the surface of the metal material 51 and connect it to a temperature recording device (not shown). Then, in the measurement of the hydrogen ingress amount, the temperature measured by the temperature sensor 20 is recorded by the temperature recording device. For example, when using a thermocouple as the temperature sensor 20, the temperature calculated from the electromotive force of the thermocouple may be recorded by the temperature recording device. As the temperature recording device, a general temperature data logger or the like can be used.

[0086] In addition, in FIG. 1, the case where one temperature sensor 20 is installed on the surface of the metal material 51 is shown, but the number of temperature sensors 20 is not limited to one, and may be any number of two or more.

[0087] For example, a plurality of temperature sensors 20 can be respectively installed at different positions on the surface of the metal material 51, and the average value of the temperatures measured by each temperature sensor 20 can be used as the temperature of the metal material 51. By using the average value of the temperatures at a plurality of positions in this way, the influence of temperature variation due to the part of the metal material 51 can be reduced, and the measurement accuracy can be further improved.

[0088] In addition, when a plurality of cells for measuring the amount of hydrogen intrusion and temperature sensors are installed respectively, when calculating the amount of intruded hydrogen from the anode current measured by the cell for measuring the amount of hydrogen intrusion and the diffusion coefficient, the diffusion coefficient may be determined using the measured temperature by the temperature sensor installed at the position closest to each cell for measuring the amount of hydrogen intrusion. Thereby, the amount of intruded hydrogen at a plurality of positions of the metallic material 51 can be calculated with higher accuracy.

[0089] (Second Embodiment) FIG. 2 is a schematic diagram showing the structure of the hydrogen intrusion amount measuring apparatus 1 and the hydrogen intrusion amount measuring kit 50 in the second embodiment of the present invention. Note that parts not particularly mentioned can be the same as those in the first embodiment above.

[0090] The hydrogen intrusion amount measuring apparatus 1 in the present embodiment further includes a first film layer 21 having insulation property disposed on the surface of the metallic material 51, and a second film layer 22 having heat conductivity and conductivity disposed on the first film layer 21. And the temperature sensor 20 is disposed on the second film layer 22. Similarly, the hydrogen intrusion amount measuring kit 50 in the present embodiment further includes a first film layer 21 having insulation property disposed on the surface of the metallic material 51, and a second film layer 22 having heat conductivity and conductivity disposed on the first film layer 21. And the temperature sensor 20 is disposed on the second film layer 22.

[0091] ·First film layer If the temperature sensor 20 is directly installed on the surface of the metallic material 51, the current generated by the temperature sensor 20 may flow through the metallic material 51, and as a result, noise may be generated in the anode current measured by the electrochemical cell 2. Therefore, as shown in FIG. 2, by installing the temperature sensor 20 through the first film layer 21 which is an insulating layer, the noise caused by the temperature sensor 20 can be reduced and the measurement accuracy can be further improved.

[0092] The material of the first film layer 21 is not particularly limited, and any insulating material can be used. Typically, the first film layer 21 may be a layer made of an organic substance, and may be an organic resin film. Examples of the material of the organic resin film include polyethylene terephthalate, acrylic resin, epoxy resin, etc. The organic resin film may be a tape composed of an organic resin film and an adhesive layer.

[0093] The thickness of the first film layer 21 is not particularly limited, but from the viewpoint of enhancing the effect of reducing noise, it is preferable that the thickness of the first film layer 21 is 1 μm or more. On the other hand, if the first film layer 21 is excessively thick, the heat conduction from the metal material 51 to the temperature sensor 20 will be inhibited. Therefore, from the viewpoint of heat conduction, it is preferable that the thickness of the first film layer 21 is 100 μm or less.

[0094] ·Second film layer By providing a second film layer 22 having thermal conductivity and electrical conductivity between the first film layer 21 and the temperature sensor 20, the measurement accuracy of temperature can be further improved.

[0095] The thermal conductivity of the second film layer 22 is not particularly limited, but from the viewpoint of reducing the difference between the surface temperature of the second film layer 22 and the surface temperature of the metal material 51, it is preferable that the thermal conductivity at 20°C is 100 W / mK or more, more preferably 200 W / mK or more, and even more preferably 400 W / mK or more. On the other hand, since the higher the thermal conductivity, the better, the upper limit is not particularly limited. However, for example, since the thermal conductivity of silver is 427 W / mK, the thermal conductivity of the second film layer 22 may be 427 W / mK or less.

[0096] The electrical conductivity of the second film layer 22 is not particularly limited, but if it is excessively low, when a thermocouple is used as the temperature sensor 20, the measurement accuracy of the thermoelectromotive force (voltage) between the thermocouples will decrease. Also, when the thermocouples are welded and fixed, the fixing force may become weak. Therefore, the electrical conductivity of the second film layer 22 is the conductivity at 20°C, 1.0×10 7It is preferably S / m, more preferably 3.0×10 7 S / m or more, and even more preferably 6.0×10 7 S / m or more. On the other hand, since the higher the conductivity, the better, the upper limit is not particularly limited. However, for example, since the conductivity of silver is 6.3×10 7 S / m, the conductivity of the second film layer 22 may be 6.3×10 7 S / m or less.

[0097] As the second film layer 22, typically, it is preferable to use a layer made of a metal material, and it is more preferable to use at least one layer selected from the group consisting of Al, Cu, and stainless steel. Among them, it is even more preferable to use a layer made of Cu with excellent conductivity. The conductivities of Al, Cu, and stainless steel at 20°C are as follows. ·Al: 3.50×10 7 S / m ·Cu: 5.98×10 7 S / m ·Stainless steel: 6.21×10 6 S / m

[0098] The thickness of the second film layer 22 is not particularly limited. However, if it is too thick, there will be disadvantages such as the increase in the weight of the hydrogen ingress measuring device. Therefore, the thickness of the second film layer 22 is preferably 100 μm or less. On the other hand, if the thickness of the second film layer 22 is too thin, it is easily torn and difficult to handle. Therefore, the thickness of the second film layer 22 is preferably 1 μm or more.

[0099] As the second film layer 22, for example, a metal foil can be used. For example, by attaching a metal foil (metal foil tape) having an adhesive layer to the surface of the metal material 51, the first film layer and the second film layer can also be formed. In this case, the adhesive layer functions as the first film layer 21, and the metal foil functions as the second film layer 22. As the metal foil tape, it is preferable to use an Al foil tape, a Cu foil tape, or a stainless steel foil tape.

[0100] It is also preferable to use the protective layer 52 as the second film layer 22. That is, as described above, on the surface of the metal material 51, a hydrogen non-invasion portion 53 covered with a protective layer 52 that prevents the intrusion of hydrogen is provided. As the protective layer 52, a metal foil attached to the surface of the metal material 51 with an organic adhesive (adhesive layer) can be used. If the temperature sensor 20 is installed on the protective layer 52, the metal foil as the protective layer 52 functions as the second film layer 22, and the adhesive layer for attaching the metal foil functions as the first film layer 21. In this way, if the temperature sensor 20 is installed on the protective layer 52, in addition to miniaturizing the device, it is not necessary to separately provide the first film layer and the second film layer, so the cost can also be reduced.

[0101] (Third Embodiment) FIG. 3 is a schematic diagram showing the structures of the hydrogen intrusion amount measuring device 1 and the hydrogen intrusion amount measuring kit 50 according to the third embodiment of the present invention. For parts not particularly mentioned, they can be the same as those in the second embodiment above.

[0102] The hydrogen intrusion amount measuring device 1 in the present embodiment further includes a third film layer that covers the temperature sensor, in addition to the first film layer 21 and the second film layer 22 described in the second embodiment. Similarly, the hydrogen intrusion amount measuring kit 50 in the present embodiment further includes a third film layer that covers the temperature sensor, in addition to the first film layer 21 and the second film layer 22 described in the second embodiment. In other words, in the present embodiment, on the surface of the metal material 51, the first film layer 21, the second film layer 22, and the third film layer 23 are laminated in order, and the temperature sensor 20 is installed between the second film layer 22 and the third film layer 23.

[0103] ·Third film layer By covering the temperature sensor 20 with the third film layer 23, corrosion of the temperature sensor 20 can be prevented. As a result, it becomes possible to perform stable measurement over a long period.

[0104] The material of the third film layer 23 is not particularly limited, but it is preferably an insulating material, and more preferably a resin. Any resin can be used without particular limitation as the resin. As the third film layer 23, for example, a silicone resin layer, an epoxy resin layer, and an acrylic resin layer can be used.

[0105] The thickness of the third film layer 23 is not particularly limited, but from the viewpoint of preventing the corrosion of the temperature sensor 20 over a long period, it is preferably 1 μm or more. On the other hand, even if the third film layer 23 is made excessively thick, the cost only increases and the anticorrosion effect saturates. Therefore, the thickness of the third film layer 23 is preferably 300 μm or less.

[0106] From the viewpoint of preventing the corrosion of the second film layer 22, it is preferable that the third film layer 23 covers not only the temperature sensor 20 but also the entire surface of the second film layer 22.

[0107] By using the hydrogen intrusion amount measuring device of the present invention, even in an environment where a temperature change occurs, the amount of hydrogen intrusion that penetrates into the interior of the metal material due to corrosion can be accurately calculated. Therefore, the hydrogen intrusion amount measuring device of the present invention can also be suitably used for monitoring the amount of hydrogen intrusion into the metal material constituting the moving body. That is, if the hydrogen intrusion amount measuring device of the present invention is attached to the metal material of a moving body such as an automobile, a ship, or a railway vehicle, the amount of hydrogen intrusion in the usage state of the moving body can be accurately and continuously measured without being affected by the temperature change. As a result, it becomes possible to accurately determine whether or not delayed fracture occurs due to hydrogen intrusion accompanying corrosion in the actual usage environment for various moving bodies.

[0108] (Fourth Embodiment) FIG. 4 is a schematic diagram showing the structures of the hydrogen intrusion amount measuring device 1 and the hydrogen intrusion amount measuring kit 50 in the fourth embodiment of the present invention. Regarding parts not particularly mentioned, they can be the same as those in the first embodiment, the second embodiment, or the third embodiment.

[0109] (Insulating coating) In this embodiment, as shown in FIG. 4, an insulating coating 9 is provided so as to cover the connection portion 8 between the electrode 5 and the coated wire 6. By providing the insulating coating 9, it becomes possible to perform stable measurement over a longer period. The reason will be described below.

[0110] In the first to third embodiments described above, as shown in FIGS. 1 to 3, the electrode 5 is provided so as to penetrate the electrolytic cell 3. And the end portion of the electrode 5 on the outside of the electrolytic cell 3 is connected to the coated wire 6, and the connection portion 8 between the electrode 5 and the coated wire 6 is in an exposed state. Therefore, for example, when measuring outdoors, the connection portion 8 may get wet due to moisture or rainwater generated by condensation.

[0111] Also, in order to install the electrode 5 as described above, it is necessary to provide a through hole in the electrolytic cell 3. At that time, in order to prevent the electrolyte 4 in the electrolytic cell 3 from leaking to the outside, it is necessary to have a structure without a gap between the electrode 5 and the electrolytic cell 3. However, when measuring the amount of hydrogen intrusion over a long period, a gap may occur between the electrode 5 and the electrolytic cell 3 due to deterioration of the material constituting the electrolytic cell, expansion, contraction, deformation, etc. caused by temperature change. When the electrolyte 4 leaks to the outside through the gap, the leaked electrolyte 4 reaches the connection portion 8 along the electrode 5.

[0112] When the connection portion 8 comes into contact with moisture such as rainwater or the electrolyte 4 in this way, an oxidation-reduction reaction also occurs on the surface of the connection portion 8, and the current thereof is included in the measured current, making it difficult to accurately measure the amount of hydrogen intrusion.

[0113] Therefore, as shown in FIG. 4, by providing the insulating coating 9 so as to cover the connection portion 8 between the electrode 5 and the coated wire 6, it is possible to prevent the connection portion 8 from coming into contact with moisture, and as a result, it becomes possible to more stably measure the amount of hydrogen intrusion.

[0114] As the insulating coating 9, any insulating material can be used, but it is preferable to use a resin, and among them, it is particularly preferable to use an epoxy resin. This is because the epoxy resin has a small shrinkage during solidification, and as a result, it is difficult to form a gap between the connection portion 8 and the insulating coating 9.

[0115] The insulating coating 9 only needs to cover at least the connection portion 8 between the electrode 5 and the coated wire 6, but as shown in FIG. 4, it may cover a wider range.

[0116] In addition, in FIG. 4, the case where the insulating coating 9 is further provided in the device of the first embodiment is shown as an example, but the insulating coating 9 can also be provided in the devices of the second and third embodiments in the same manner.

[0117] (Fifth Embodiment) FIG. 5 is a schematic diagram showing the structures of the hydrogen intrusion amount measuring device 1 and the hydrogen intrusion amount measuring kit 50 in the fifth embodiment of the present invention. For parts not particularly mentioned, the same as the fourth embodiment above can be adopted.

[0118] (Void Portion) In the present embodiment, a void portion 11 is provided inside the insulating coating 9 described in the fourth embodiment, and the electrode 5 is arranged so as to penetrate the void portion 11.

[0119] FIG. 5 is a schematic diagram showing an example of the arrangement of the void portion in the present embodiment. The void portion 11 is a cavity provided inside the insulating coating 9. When the void portion 11 is provided as shown in FIG. 5, even if the electrolytic solution 4 leaks from the portion where the electrode 5 penetrates the electrolytic cell 3, it is trapped by the void portion 11, so that the leaked electrolytic solution 4 can be prevented from reaching the connection portion 8 between the electrode 5 and the coated wire 6. Therefore, by providing the insulating coating 9 as described in the fourth embodiment above and further providing the void portion 11 in the insulating coating 9, the measurement of the hydrogen intrusion amount can be performed more stably over a long period.

[0120] The number of the void portions 11 is not particularly limited, and the number of void portions per electrochemical cell (i.e., per insulation coating) may be one or two or more.

[0121] For example, as shown in FIG. 5(a), a structure in which one void portion 11 is penetrated by two electrodes 5c and 5r may be used. Also, as shown in FIG. 5(b), two void portions 11 may be provided inside the insulation coating 9, and the electrodes 5c and 5r may have a structure in which they penetrate different void portions 11, respectively. Further, a structure in which one electrode 5 penetrates a plurality of void portions 11 may be used.

[0122] In any case, it is important that the electrode 5 is arranged so as to penetrate the void portion 11. In other words, the void portion 11 is located on the side of the electrolytic cell 3 rather than the connection portion 8 between the electrode 5 and the covering wire. This is because it is necessary to trap the leaked electrolytic solution 4 in the void portion 11 before it reaches the connection portion 8.

[0123] [Method for Measuring Amount of Ingress Hydrogen] Next, a method for measuring the amount of ingress hydrogen using the apparatus or kit for measuring the amount of ingress hydrogen of the present invention will be described. The measuring method described below can be applied to any of the apparatuses of the first to fifth embodiments described above.

[0124] The method for measuring the amount of ingress hydrogen of the present invention is a method for measuring the amount of hydrogen that has penetrated into the interior of a metal material 51 due to corrosion by an electrochemical hydrogen permeation method. In the measurement, as shown in FIGS. 1 to 4, a plurality of electrochemical cells 2 are installed on one surface of the metal material 51 as a test specimen. One of the plurality of electrochemical cells 2 is used as a reference cell, and the rest are used as cells for measuring the amount of hydrogen ingress.

[0125] On the other side of the metal material 51, a hydrogen non-invasion part 53 covered by a protective layer 52 that prevents the intrusion of hydrogen and a hydrogen invasion part 54 where the protective layer 52 is not provided are formed. Then, an electrochemical cell 2a as a reference cell is arranged on the opposite side of the hydrogen non-invasion part 53, and a hydrogen invasion measurement cell 2b is arranged on the opposite side of the hydrogen invasion part 54.

[0126] During the measurement, the anode current value measured by the hydrogen invasion measurement cell 2b is corrected using the passive current measured by the reference cell 2a. The correction can be performed according to the method disclosed in Patent Document 1.

[0127] That is, in order to evaluate the amount of hydrogen intrusion, it is necessary to measure the current (permeated hydrogen current) caused by the electrochemical reaction of the permeated hydrogen in the hydrogen invasion measurement cell 2b. However, the anode current actually measured by the hydrogen invasion measurement cell 2b includes not only the current caused by the reaction of hydrogen but also the passive current. Therefore, the permeated hydrogen current can be obtained by subtracting the passive current measured by the reference cell 2a from the anode current measured by the hydrogen invasion measurement cell 2b. However, in actual calculations, it is necessary to use current density instead of current value. That is, by subtracting the passive current density measured by the reference cell 2a from the anode current density measured by the hydrogen invasion measurement cell 2b, the permeated hydrogen current density i H (A / cm 2 ) is obtained.

[0128] In addition, the conversion from current to current density can be performed by dividing the current value measured by the electrochemical cell 2 by the measurement area (the area of the part where the electrolyte 4 contacts the metal material 51) in the electrochemical cell 2.

[0129] On the other hand, a temperature sensor 20 is installed on the surface of the metal material 51 to measure the temperature of the metal material 51. Then, using the measured temperature of the metal material 51, the diffusion coefficient of hydrogen in the metal material 51 at that temperature is obtained. For calculating the diffusion coefficient, the following formula (1) (Arrhenius equation) representing the temperature dependence of the diffusion coefficient D can be used.

[0130] In addition, in order to calculate the diffusion coefficient by formula (1), D in the metal material to be measured 0 and the value of Q need to be obtained in advance. D 0 There is no particular limitation on how to obtain the values of and Q. For example, by performing measurements in advance under a plurality of temperature conditions and creating a so-called Arrhenius plot, D in the metal material as the specimen can be obtained from the intercept and slope thereof 0 and the value of Q. Then, during actual measurement, from the temperature T measured by the temperature sensor 20 and the values of D 0 and Q obtained in advance, the diffusion coefficient D at the temperature T can be obtained using the following formula (1). D = D 0 × exp{-Q / (R × T)}… (1) Here D: Diffusion coefficient (m 2 / s) D 0 : Constant independent of temperature (m 2 / s) Q: Activation energy of diffusion (kJ / mol) R: Gas constant (8.314 J / mol·K) T: Temperature (K) That is

[0131] By the above procedure, the anode current (permeated hydrogen current density i H with the influence of the passive holding current corrected and the diffusion coefficient D can be obtained. Then, the amount of hydrogen permeated can be calculated from the obtained permeated hydrogen current density i H and the diffusion coefficient D

[0132] Here, the amount of hydrogen permeated in the electrochemical hydrogen permeation method is calculated as the amount of hydrogen permeated C ab The amount of hydrogen permeated refers to the adsorbed hydrogen concentration on the hydrogen permeation surface

[0133] And the amount of hydrogen permeated C ab can be calculated by the following formula (2). Cab = (i H×L) / (D×F×d)…(2) Here, C ab : Amount of hydrogen intrusion (mass ppm) i H : Hydrogen permeation current density i H (A / cm 2 ) L: Thickness of the test piece (cm) D: Hydrogen diffusion coefficient in the metal material of the test piece (cm 2 / s) F: Faraday constant (C / mol) d: Density of the metal material (g / cm 3 ) is.

[0134] As described above, by using both the correction of the passive holding current by the reference cell and the correction of the temperature dependence of the diffusion coefficient by the temperature sensor, the amount of hydrogen intrusion can be measured with extremely high accuracy.

Example

[0135] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0136] In this example, the amount of hydrogen intrusion into the metal material 51 was measured using the hydrogen intrusion amount measuring device 1 shown in FIGS. 1 to 4.

[0137] As the metal material 51, a steel plate with a thickness of 0.5 mm was used. Specifically, either of the following (a) and (b) was used as the steel plate. The types of steel plates used are shown in the "Metal Material" column of Tables 1 and 2. (a) Soft steel plate of 270 MPa grade (b) High-strength steel plate of 1470 MPa grade

[0138] On one surface of the steel plate (the lower surface in FIGS. 1 to 4), a Pd plating layer (thickness: 100 nm) was formed as a metal layer, and an electrochemical cell 2 equipped with an electrolytic cell 3 was installed on its surface. The materials of the electrolytic cell 3, counter electrode 5c, and reference electrode 5r used are shown in Tables 1 and 2.

[0139] The counter electrode 5c and the reference electrode 5r of each electrochemical cell 2 were connected to the power supply PS for electrochemical measurement using the coated wire 6. Also, the metal material 51 serving as the working electrode was connected to the power supply PS for electrochemical measurement using the coated wire 7. As the power supply PS for electrochemical measurement, a multi-channel potentiostat was used.

[0140] The electrolytic solution 4 was put into the electrolytic cell 3 of each electrochemical cell 2 so that the liquid level contacted the surface of the metal material 51. As the electrolytic solution 4, a 0.1 M NaOH aqueous solution with a pH of 13 was used.

[0141] On the other hand, the surface on the opposite side of the electrochemical cell 2a (reference cell) was coated with a protective layer 52 to form a hydrogen non-invasion part 53. The protective layer 52 was composed of two layers, a polyethylene terephthalate layer (thickness: 5 μm) and a Cu layer on the polyethylene terephthalate layer (thickness: 40 μm). The polyethylene terephthalate layer was formed by attaching a tape composed of a polyethylene terephthalate support and an adhesive layer. Also, the Cu layer was formed by attaching a Cu foil tape composed of a Cu foil and an adhesive layer.

[0142] The temperature sensor 20 was installed on the upper surface of the steel plate (the same side as the protective layer 52). However, for comparison, in some examples, the temperature sensor 20 was not used. As the temperature sensor 20, a wire-shaped thermocouple was used and connected to a temperature data logger (not shown) to continuously record the temperature during the measurement of the amount of invading hydrogen.

[0143] The installation forms of the temperature sensor 20 were three as shown in FIGS. 1 to 3. That is, in some embodiments, the temperature sensor 20 was directly installed on the surface of the steel plate as shown in FIG. 1. Also, in some embodiments, as shown in FIG. 2, a first film layer 21 having insulation and a second film layer 22 having thermal conductivity and conductivity were provided on the surface of the steel plate, and the temperature sensor 20 was installed on the surface thereof. Further, in other embodiments, as shown in FIG. 3, the surface of the temperature sensor 20 was coated with a third film layer 23. The presence or absence of the first film layer 21, the second film layer 22, and the third film layer 23, the material of the second film layer 22, and the thickness of the first film layer 21 are shown in Tables 1 and 2. Note that a polyethylene terephthalate film was used as the first film layer 21, and a silicone resin film was used as the third film layer.

[0144] Also, in some embodiments, as shown in FIG. 4, an insulation coating 9 was provided for each of the electrochemical cells 2. Further, in some of the embodiments using the insulation coating 9, a void portion 11 was formed inside the insulation coating 9 as shown in FIG. 5(b). The presence or absence of the insulation coating 9 and the void portion 11 are shown in Tables 1 and 2.

[0145] When measuring the amount of hydrogen intrusion, the above-described hydrogen intrusion measuring device was installed in an atmospheric exposure environment with the device installed on the steel plate, and the anode current value was continuously measured. Then, the amount of hydrogen intrusion was calculated from the measured anode current value using the above-described formula (2). In the above measurement, anodic polarization was performed so that the potential became 0.2 V in each of the electrochemical cell 2a (reference cell) and the electrochemical cell 2b (cell for measuring the amount of hydrogen intrusion).

[0146] In calculating the amount of hydrogen intrusion, first, the diffusion coefficient D of hydrogen in the metal material at the measured temperature was obtained from the temperature of the metal material measured by the temperature sensor 20 using the above-described formula (1). Then, the amount of hydrogen intrusion was calculated by formula (2) using the obtained diffusion coefficient D. Note that D used for calculating the diffusion coefficient D 0The values of 0 and Q were determined in advance using the same metal material. Specifically, measurements were performed by a general electrochemical hydrogen permeation method, and the diffusion coefficients D at two conditions of 40°C and 20°C were measured by the Breakthrough-time method. From the measured values, an Arrhenius plot was created to obtain the values of D

[0147] (Effect of temperature) To confirm the effect of temperature on the calculation of the amount of hydrogen intrusion, the amount of hydrogen intrusion was calculated by the following three methods. The amount of hydrogen intrusion was calculated from the anode current value in Example No. 35 by performing continuous measurements for 24 hours on a sunny day in summer. Note that the permeated hydrogen current density i H after correcting the passive holding current was 43.9 nA / cm 2 .

[0148] (Condition 1) The diffusion coefficient D was calculated using the average value (27.0°C) of the temperature of the environment (ambient temperature) on the above-mentioned day, and the amount of hydrogen intrusion was determined using the obtained diffusion coefficient D. The obtained amount of hydrogen intrusion was 0.0094 ppm.

[0149] (Condition 2) The diffusion coefficient D was calculated using the temperature (29.0°C) of the environment at the time when the above-mentioned anode current value was measured, and the amount of hydrogen intrusion was determined using the obtained diffusion coefficient D. The obtained amount of hydrogen intrusion was 0.0088 ppm.

[0150] (Condition 3) The diffusion coefficient D was calculated using the temperature (60.0°C) of the steel plate measured by the temperature sensor 20 at the time when the above-mentioned anode current value was measured, and the amount of hydrogen intrusion was determined using the obtained diffusion coefficient D. The obtained amount of hydrogen intrusion was 0.0034 ppm.

[0151] Thus, it can be seen that in an actual measurement environment, a large deviation may occur between the temperature of the metal material and the temperature of its surroundings (ambient temperature), and as a result, a large error may occur in the calculated amount of hydrogen intrusion.

[0152] (Measurement accuracy) Next, the measurement accuracy of the amount of hydrogen intrusion was evaluated. For this evaluation, on the same day as the evaluation of the temperature effect described above, continuous measurement was performed for 24 hours under each condition shown in Tables 1 and 2, and the amount of hydrogen intrusion during that period was measured. Based on the following criteria, the measurement accuracy was evaluated from the obtained amount of hydrogen intrusion. For the examples using a 270 MPa grade mild steel plate as the test specimen, the amount of hydrogen intrusion in Example No. 15 was used as the reference amount of hydrogen intrusion. For the examples using a 1470 MPa grade high-strength steel plate as the test specimen, the amount of hydrogen intrusion in Example No. 35 was used as the reference amount of hydrogen intrusion. Excellent: Deviation from the reference amount of hydrogen intrusion is 10% or less Good: Deviation from the reference amount of hydrogen intrusion exceeds 10% and is 20% or less Fair: Deviation from the reference amount of hydrogen intrusion exceeds 20% and is 30% or less Poor: Deviation from the reference amount of hydrogen intrusion exceeds 30%

[0153] In Comparative Examples No. 1 and 21 where the temperature sensor 20 was not used, instead of the temperature of the metal material 51 measured by the temperature sensor 20, the average value of the outside air temperature (ambient temperature) was used to calculate the diffusion coefficient D.

[0154] As shown in Tables 1 and 2, excellent measurement accuracy was obtained in the inventive examples that satisfied the conditions of the present invention.

[0155] (Lifetime) Furthermore, in order to evaluate the lifetime of the hydrogen intrusion measuring device, the anode current value was continuously measured over a long period of one year or more. The measured anode current is usually a positive current value, but when a negative current value is measured and normal measurement cannot be performed, the time point is defined as the lifetime of the device, and the lifetime was evaluated according to the following criteria. 4: Lifetime is 2 years or more 3: Lifetime is more than 1 year and less than 2 years 2: Lifetime is more than 0.5 year and less than 1 year 1: Lifetime is less than 0.5 year

[0156]

Table 1

[0157]

Table 2

Explanation of Symbols

[0158] 1 Hydrogen Ingress Measurement Device 2 Electrochemical Cell 2a Reference Cell 2b Cell for Measuring Hydrogen Ingress 3 Electrolytic Cell 4 Electrolyte 5 Electrode 5c Counter Electrode 5r Reference Electrode 6 Coated Wire 7 Coated Wire 8 Connection Part 9 Insulating Coating 11 Void Part 20 Temperature Sensor 21 First Film Layer 22 Second Film Layer 23 Third Film Layer 50 Hydrogen Ingress Measurement Kit 51 Metal Material 52 Protective Layer 53 Hydrogen Non-Invasive Part 54 Hydrogen Invasive Part 100 Hydrogen Ingress Measurement System PS Power Supply for Electrochemical Measurement (Potentiostat)

Claims

1. An apparatus for measuring the amount of hydrogen invading into the interior of a metal material by corrosion, which measures the amount of hydrogen invading into the interior of a metal material by corrosion by an electrochemical hydrogen permeation method, and includes: a temperature sensor installed on the surface of the metal material; a plurality of electrochemical cells installed on one surface of the metal material; The apparatus for measuring the amount of hydrogen invading.

2. The apparatus for measuring the amount of hydrogen invading according to claim 1, further comprising: a first film layer having insulation properties, disposed on the surface of the metal material; a second film layer having thermal conductivity and conductivity, disposed on the first film layer; wherein the temperature sensor is disposed on the second film layer.

3. The apparatus for measuring the amount of hydrogen invading according to claim 2, wherein the thickness of the first film layer is 1 to 100 μm.

4. The apparatus for measuring the amount of hydrogen invading according to claim 2, wherein the second film layer is a metal layer composed of at least one selected from the group consisting of aluminum, copper, and stainless steel.

5. The apparatus for measuring the amount of hydrogen invading according to claim 2, further comprising: a third film layer covering the temperature sensor.

6. A kit for measuring the amount of hydrogen invading into the interior of a metal material by corrosion, which measures the amount of hydrogen invading into the interior of a metal material by corrosion by an electrochemical hydrogen permeation method, and includes: the metal material as a test object; a temperature sensor installed on the surface of the metal material; a plurality of electrochemical cells installed on one surface of the metal material; wherein a hydrogen non-invading portion covered by a protective layer for preventing hydrogen invasion and a hydrogen invading portion where the protective layer is not provided are formed on the other surface of the metal material; one of the plurality of electrochemical cells is disposed on the opposite surface of the hydrogen non-invading portion; the remaining of the plurality of electrochemical cells are disposed on the opposite surface of the hydrogen invading portion.

7. The kit for measuring the amount of hydrogen invading according to claim 6, further comprising: a first film layer having insulation properties, disposed on the surface of the metal material; a second film layer having thermal conductivity and conductivity, disposed on the first film layer; wherein the temperature sensor is disposed on the second film layer.

8. The kit for measuring the amount of hydrogen invading according to claim 7, wherein the thickness of the first film layer is 1 to 100 μm.

9. The kit for measuring the amount of hydrogen invading according to claim 7, wherein the second film layer is a metal layer composed of at least one selected from the group consisting of aluminum, copper, and stainless steel.

10. The hydrogen ingress amount measurement kit according to claim 7, further comprising a third film layer that coats the temperature sensor.

11. A method for measuring the amount of hydrogen that has penetrated into a metal material due to corrosion by means of an electrochemical hydrogen permeation method, placing a plurality of electrochemical cells on one surface of the metal material as the test specimen, designating one of the plurality of electrochemical cells as a reference cell and the remaining cells as hydrogen ingress measurement cells, forming, on the other surface of the metal material, a hydrogen non-ingress portion covered with a protective layer that prevents hydrogen ingress and a hydrogen ingress portion where the protective layer is not provided, placing the reference cell on the opposite side of the hydrogen non-ingress portion, placing the hydrogen ingress measurement cells on the opposite side of the hydrogen ingress portion, correcting the anodic current value measured by the hydrogen ingress measurement cells using the passive current holding current measured by the reference cell, installing a temperature sensor on the surface of the metal material to measure the temperature of the metal material, determining the diffusion coefficient of hydrogen in the metal material from the temperature of the metal material, A method for measuring the amount of hydrogen ingress, calculating the amount of hydrogen ingress from the corrected anodic current and the diffusion coefficient.

12. placing a first film layer having insulation properties on the surface of the metal material, placing a second film layer having thermal conductivity and electrical conductivity on the first film layer, placing the temperature sensor on the second film layer, the method for measuring the amount of hydrogen ingress according to claim 11.

13. The method for measuring the amount of hydrogen ingress according to claim 12, wherein the thickness of the first film layer is 1 to 100 μm.

14. The method for measuring the amount of hydrogen ingress according to claim 12, wherein the second film layer is a metal layer composed of at least one selected from the group consisting of aluminum, copper, and stainless steel.

15. The method for measuring the amount of hydrogen ingress according to claim 12, further comprising a third film layer that coats the temperature sensor.

Images