TWI502196B - Measurement device for intrusion of hydrogen into the metal - Google Patents

Description

Measuring device for invading hydrogen in the interior of metal

The present invention relates to a measuring device capable of accurately detecting the amount of invading hydrogen in the interior of a metal which can accurately detect the amount of hydrogen intruding into the metal accompanying corrosion of the metal.

In recent years, from the viewpoint of preventing global warming, the energy efficiency is improved by reducing the weight of automobiles, ships, and railway vehicles as mobile bodies. For example, if it is a car, the fuel consumption rate of gasoline is pursued. improve. Therefore, in order to reduce the thickness of the constituting material, particularly the steel material, the same amount of safety is ensured, and the amount of the steel material having high strength is increased.

However, it is known that if the strength of the steel is increased, a phenomenon called "delay breaking" tends to occur. This "delayed breaking" is remarkably intensified with an increase in the strength of the steel material, and the high-strength steel having a tensile strength of 1,180 MPa or more is particularly remarkable (Non-Patent Document 1). In addition, the term "delayed breaking" means that a high-strength steel is subjected to static load stress (load stress below tensile strength), and when subjected to a certain period of time, there is almost no plastic deformation in appearance. The sudden occurrence of brittle fracture, here, means that the hydrogen embrittlement type is delayed due to hydrogen entering the steel.

The hydrogen which invades the steel material can be considered to be caused by corrosion of the steel sheet, and is partially caused by intrusion into the steel material. From this point of view, various evaluation methods for delaying the breakage of hydrogen into steel materials have been proposed.

For example, in Patent Document 1, in the evaluation method of the delayed fracture characteristic (the steel material is filled with diffusible hydrogen by the cathode of the steel material to measure the amount of the terminally diffusible hydrogen, thereby evaluating the delayed fracture characteristics of the steel material) A method of galvanizing a steel material in order to prevent hydrogen from being released from the steel in the measurement of the ultimate diffusible hydrogen amount has been proposed.

However, in the technique described in Patent Document 1, the hydrogen intrusion into the steel is accelerated by the cathode filling, and the hydrogen intrusion is accelerated. Therefore, it can be judged that the supply is different under the conditions different from the actual use environment. The type of the test material is used to find out the advantages and disadvantages of delayed fracture, but it cannot be used as a judgment material for estimating whether the amount of hydrogen intrusion accompanying corrosion in the actual use environment causes delayed fracture.

In recent years, many reports have focused on the study of hydrogen intrusion. For example, in Non-Patent Document 2, it is reported that hydrogen intrusion behavior using ammonium thiocyanate is reported. In Non-Patent Document 2, a comparison is made between hydrogen intrusion by ammonium thiocyanate and hydrogen intrusion by a cathode filling method.

However, in the method for evaluating the amount of hydrogen intrusion using ammonium thiocyanate disclosed in Non-Patent Document 2, hydrogen intrusion due to corrosion of the surface cannot be obtained, and it is not possible to measure, for example, use as an automobile for rust prevention in recent years. The effect of galvanizing and the like on hydrogen intrusion.

Further, in Non-Patent Document 3, an example of recovering a high-strength screw that has been corroded during a fixed period in an atmospheric exposure environment and measuring the concentration of hydrogen absorbed in the screw is reported. Further, in Non-Patent Document 3, there is reported a result of electrification by using a test apparatus that exposes a single side of a steel sheet to an external environment. The hydrogen permeation method was studied, and the hydrogen intrusion behavior caused by corrosion in an atmospheric exposure environment was investigated based on the change in the anode current value detected from the opposite side.

However, the data obtained by the atmospheric exposure test disclosed in Non-Patent Document 3 are only the test results under the environmental factors of the specific environment of the terrain, and the continuous consideration of various environments accompanying the movement of the structure is not considered. Corrosion underneath.

Further, in the hydrogen permeation test under atmospheric exposure using the test apparatus which exposes the one surface of the steel plate to the external environment as shown in Non-Patent Document 3, since the change of the residual current on the anode side accompanying the change in the ambient temperature is not considered, There is also a problem with the quantitative nature of the measured values.

Furthermore, as described above, although the metal material which is currently the most worrying about the problem of delayed breakage is widely used as a practical material, it is also pointed out that it is possible to delay the breakage of other metal materials in the future. Problem (for example, Non-Patent Document 4).

As described above, in a moving body such as an automobile, the terrain environment changes due to the movement, and further, if physical factors (such as vibration, dust accumulation/shedding, water, mud splash adhesion, drying, etc.) are added, there is The situation in which the corrosive environment changes extremely.

However, as for the moving body incapable of avoiding the physical factors such as the above vibration or the change in the terrain environment, there has been no example of continuously and quantitatively measuring the amount of hydrogen intrusion accompanying the corrosion.

In view of the above situation, the inventors and the like first developed: "A method for measuring the amount of invading hydrogen in the interior of a metal, which is a method for measuring the amount of hydrogen generated by the corrosion of a metal material and invading the inside of the metal by an electrochemical hydrogen permeation method, and is characterized in that one side of the object to be detected is used The surface of the object to be detected is used as a hydrogen detection surface, and the potential of the hydrogen detection surface side is maintained at -0.1 to + In the state of 0.3 V vs. SCE, the flow of hydrogen diffused to the detection surface is measured as an anode current. At this time, an electrochemical element is disposed on the hydrogen detection surface side of the sample, and the electrochemical element is disposed. A plurality of cell groups divided into at least two cells are formed, and each cell of the cell group is filled with an electrolyte aqueous solution having a pH of 9 to 13 and simultaneously provided with independent reference electrodes and opposite electrodes. At least one unit of the group is used as a reference unit for correcting the residual current, and a protective film for blocking contact with the corrosive environment is provided at a portion of the reference unit corresponding to the hydrogen intrusion surface side, according to the reference A cell detecting residual current value of the anode current value is corrected to a unit other than the reference cell is detected, the anode current based on the calculated correction value from this by the amount of hydrogen ingression of the side. "

And disclosed in Patent Document 2.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2005-69815

Patent Document 2: Japanese Patent Application No. 2010-42800

[Non-patent literature]

Non-Patent Document 1: "Song Shan Jin Zuo: Delayed Breaking, Nikkan Kogyo Shimbun, Tokyo, (1989)"

Non-Patent Document 2: "▲高▼井等: Corrosion and Erosion Paper Collection, Vol.170, p.47-54 (2010)"

Non-Patent Document 3: "Damura et al.: Iron and Steel, VoL. 91, No. 5, p. 42 (2005)"

Non-Patent Document 4: "High Take, etc.: Iron and Steel, Vol. 78, No. 5, p. 149 (1992)"

Non-Patent Document 5: "M.A.V. Devanathan, Z. Stachurski; Proc. Roy. Soc. London, Ser. A, 270, 90 (1962)"

According to the development of Patent Document 2 described above, it is possible to accurately measure the amount of hydrogen invading the inside of the metal accompanying the corrosion in consideration of the change in the residual current on the anode side accompanying the change in the ambient temperature.

An object of the present invention is to provide a measuring device for injecting hydrogen into the interior of a metal which is preferably a method for measuring the amount of invading hydrogen in the metal described in Patent Document 2.

That is, the gist of the present invention is as follows.

1. A measuring device for invading a hydrogen content into a metal, which is an apparatus for measuring the amount of hydrogen generated by intrusion of a metal formed of a metal material and intruding into a metal by an electrochemical hydrogen permeation method. When the surface on one side of the object to be tested is exposed to a corrosive environment and serves as an intrusion surface of hydrogen generated by a corrosion reaction, and the surface on the other side is a hydrogen detection surface An electrochemical element composed of a plurality of cell groups is disposed on the hydrogen detection surface side, and each of the cells of the cell group is filled with an electrolyte aqueous solution having a pH of 9 to 13 and simultaneously provided with independent reference electrodes. And the opposite electrode, the at least one unit of the unit group is used as a reference unit for correcting the residual current, and is disposed in the region of the hydrogen intrusion surface side of the reference unit corresponding to the hydrogen detection region for blocking and etching a protective film in contact with the environment, and correcting an anode current value detected by the unit other than the reference unit according to the residual current value detected by the reference unit, and calculating the corrosion from the corrosion based on the corrected anode current value The amount of hydrogen intrusion on the face side.

2. The apparatus for measuring the amount of invading hydrogen in the metal as described above, wherein an Ir/Ir oxide electrode is used as the reference electrode.

3. The apparatus for measuring the amount of invading hydrogen in the interior of the metal according to the above 1 or 2, wherein an organic compound for preventing freezing is added to the aqueous electrolyte solution.

4. The apparatus for measuring the amount of invading hydrogen in the interior of the metal according to the above 1, 2 or 3, wherein the organic compound added to the aqueous electrolyte solution is isopropanol, glycerin, ethylene glycol, dimethyl hydrazine or two. Methylformamide.

5. The apparatus for measuring the amount of invading hydrogen in the interior of the metal according to any one of the above 1 to 4, wherein the inside of the electrochemical element filled with the aqueous electrolyte solution is disposed so as to avoid contact with the hydrogen detecting surface. bubble.

According to the apparatus of the present invention, the amount of hydrogen invading into the interior of the metal accompanying the corrosion can be accurately detected.

Further, if the apparatus of the present invention is used, the amount of hydrogen intruding into the metal material can be continuously monitored, and information necessary for judging whether the amount of hydrogen intrusion accompanying corrosion in the actual use environment is delayed or not can be obtained. This hydrogen system is generated by corrosion of various parts of a metal material constituting a moving body such as an automobile, a ship, or a railway vehicle in a state of use and exposure to a corrosive environment.

The present invention can be applied to various vehicles such as automobiles, two-wheeled vehicles, railways, and the like, and all the movable bodies that can be moved by their own forces, and the following describes the embodiments in detail by using a car as a representative example. The metal material to be evaluated is not necessarily limited to a steel sheet, but a case where it is applied to a steel sheet will be described as a representative example.

The present invention is applicable to the measurement principle of the electrochemical hydrogen permeation method to measure the amount of hydrogen generated by the corrosion of the metal material and intruded into the interior, and the surface of the steel sheet invading the surface of the hydrogen is exposed to a corrosive environment, and the corrosion is generated. Since hydrogen intrudes into the steel, the amount of invading hydrogen is measured by extracting hydrogen from the opposite side.

The Electrochemical Hydrogen Permeation System was developed in 1962 by Devanathan and As a method developed by Stachurski (Non-Patent Document 5), as shown in Fig. 1, the two electrolytic cells 1a and 1b are placed to face each other with one sample 2 interposed therebetween. In the case of the figure, hydrogen is generated by cathodic polarization of the left side of the test surface of the electrolytic cell 1a at a constant potential or a constant current. The hydrogen is filled, and the hydroxide of the permeated sample 2 is hydrogen ion by constant-potential anodic polarization of the sample 2 in the electrolytic cell 1b on the right side, and the amount of hydrogen permeated is determined based on the current value.

In the figure, the symbols 3a and 3b are reference electrodes, and 4a and 4b are electrodes. In particular, 4b is referred to as a counter electrode or a coefficient electrode. Further, the electrode 4a is connected to a potentiostat that imparts a constant potential or a galvanostat that supplies a constant current, and on the other hand, the electrode 4b is connected to a potentiostat that gives a constant potential. Further, 5a and 5b are fritted glass powders for removing the influence of gases generated in the counter electrodes 4a and 4b.

The above-described electrochemical hydrogen permeation method is itself a method known as "method for measuring the diffusion coefficient of hydrogen in a steel sheet".

As shown in Fig. 1, the original electrochemical hydrogen permeation method is a method in which one side of a sample is used as a cathode to perform electrolysis of hydrogen, and the opposite side is used as an anode, but it is reported that the application will be The study corresponding to the surface of the hydrogen filling surface side exposed to a corrosive environment (Non-Patent Document 3).

However, in the measurement method disclosed in Non-Patent Document 3, as described above, there is a problem that the change in the measured current value due to the temperature change is not considered. Further, the anode electric quantity measured on the hydrogen detecting surface side by electrochemical hydrogen permeation method In the flow, in addition to the oxidation current of hydrogen, the passivation current of the test material is superimposed. The passive state keeps the current system as the main body of the residual current, which is affected by various factors, but the change due to temperature is large.

Since the anode current measured by the electrochemical hydrogen permeation method on the hydrogen detection surface side is a weak current, the anode current cannot be accurately measured without correcting the temperature dependency of the residual current.

In order to solve the above problems, the present inventors have conducted various studies in turn, and as a result, an electrochemical device disposed on the hydrogen detecting surface side is configured by dividing a plurality of cell groups into at least two or more cells on the same object. a component, wherein at least one of the cells is set as a reference cell for correcting a residual current, and a protective film for blocking a corrosive environment is provided by a region of the reference cell that is opposite to a hydrogen intrusion surface side of the hydrogen detection region, This can be used as a measure of the temperature dependence of the residual current.

An example of the measuring apparatus of the present invention is schematically shown in Fig. 2 . In the example of Fig. 2, four units 7a, 7b, 7c, and 7d are provided on the hydrogen detecting surface side of the steel sheet 6 as the object to be detected, and the leftmost unit 7a is set as a reference unit for correcting the residual current. Happening. In the figure, reference numeral 8 is a counter electrode (Pt line), and 9 is a reference electrode (Ir line). Further, in the present invention, the number of the cells may be at least two, and if the number of cells is too large, the processing becomes complicated. Therefore, it is preferable to set the maximum number to four.

In the figure, the surface temperature of the steel sheet in each unit, the temperature of the electrolyte solution in the unit, and the like are all set to the same temperature. Also, hydrogen in the reference unit 7a A protective film 10 is provided on the intrusion surface side. Since the portion covered by the protective film 10 does not cause corrosion, hydrogen does not intrude, and it is considered that the current measured on the hydrogen detecting surface side of the reference cell is the residual current itself.

In Fig. 3, the reaction on the etching surface (hydrogen intrusion surface) side and the hydrogen detection surface side of a unit (also referred to as a channel) having no protective film is schematically shown.

By maintaining the surface potential of the hydrogen detecting surface side at a potential sufficient for the ionization reaction of hydrogen, all of the hydrogen which has reached the detection surface side by diffusion is taken out as hydrogen ions. Further, in the present invention, the surface of the steel sheet on the side of the hydrogen detecting surface is passivated. Thereby, it can be considered that the anode current detected on the hydrogen detection side actually corresponds to the hydrogen permeation current.

Therefore, by correcting the current value obtained in this manner due to the residual current value obtained by the reference unit, the correct anode current value can be measured regardless of the change in the residual current accompanying the temperature change, and the result is based on the anode. The current value is used to calculate the correct amount of invading hydrogen.

In the present invention, in order to keep the steel sheet on the hydrogen detecting surface side in a passive state, it is necessary to set the solution in the anode electrode chamber to an electrolyte solution having a pH of 9 to 13. This is because if the pH is less than 9, it is difficult to maintain the passive state of the surface of the steel sheet at a predetermined potential. On the other hand, if the pH exceeds 13, the environmental damage is greatly caused when it leaks due to an accident. As the electrolyte solution of a suitable pH value, an aqueous NaOH solution of about 0.1 to 0.2 M (mol/liter) is preferred. Furthermore, in the present invention, the electrolyte solution as a suitable pH value is not necessarily limited to a 0.1 to 0.2 M aqueous NaOH solution, as long as In order to maintain the potential of the ionization reaction of hydrogen when the surface of the steel sheet on which the hydrogen detecting surface is sufficient is sufficient, an electrolyte solution which ensures the passivation state of the surface of the steel sheet can be used. Further, the use of a gel-like electrolyte instead of the electrolyte solution not only prevents liquid leakage but also facilitates handling and is advantageous.

Further, in the present invention, it is necessary to maintain the potential of the hydrogen detecting surface at -0.1 to +0.3 V vs SCE. This is because if the potential of the hydrogen detecting surface is outside the range, stable ionized current of hydrogen cannot be obtained.

Here, SCE (Saturated Calomel Electrode) means a saturated calomel electrode, and the potential of the SCE with respect to a standard hydrogen electrode (SHE, Standard Hydrogen Electrode) is represented by +0.244 V (vs SHE, 25 ° C).

Further, as the reference electrode for controlling the potential, various electrodes which have been put to practical use can be used.

However, in the case of using an electrode including a chloride such as an Ag/AgCl electrode, the residual current is increased due to the contamination of the surface of the sample caused by the contamination of the chloride electrode solution in the anode chamber solution, and the residual current is increased. The value becomes inaccurate.

Therefore, various studies have been conducted on the reference electrode which can avoid the above problem, and as a result, it has been found that the Ir/Ir oxide electrode is obtained by immersing the Ir line in the anode electrode solution solution, whereby a potential which is stable for a long period of time can be obtained. That is, the electrode which is optimal as the reference electrode is an Ir/Ir oxide electrode, and a potential of about -0.04 vs SSE can be stably obtained.

Here, SSE (Silver-Silver chloride Electrode) is silver-silver chloride The potential of the SSE relative to the standard hydrogen electrode (SHE) is represented by +0.199 V (vs SHE, 25 ° C).

Further, in the present invention, it is preferred that the surface of the hydrogen detecting surface has a large hydrogen diffusion constant and is covered with a metal such as a hydrogen-promoting oxidation reaction. Examples of such a metal include Pd or Pd alloy and Ni. Wait. By being covered by the metals or alloys, not only can the residual current of the hydrogen detecting surface be kept low, but also the hydrogen intrusion reaction at the side of the hydrogen detecting surface can be promoted, thereby improving hydrogen generation. The sensitivity of the anode current caused by ionization. Furthermore, the Pd system has a larger hydrogen diffusion constant than Ni, and has the advantage of reducing the residual current.

To be covered by the case of Pd or Pd alloy, since Keji _{[Pd (NH 3) 4]} Cl 2. Cathodic electrolysis is carried out in an aqueous solution containing palladium ions such as H ₂ O to carry out plating. As the Pd alloy, a Pd-Ni or Pd-Co alloy or the like can be used. Here, it is preferable to set the film thickness of Pd plating or Pd alloy plating to 10 to 100 nm.

Further, in the case where it is covered with Ni, Ni plating can be performed by cathodic electrolysis in a known plating bath such as a Watts bath. The film thickness of the Ni plating is also preferably set to 10 to 100 nm.

Further, Pd or a Pd alloy may be plated on the Ni plating.

The protective film provided on the hydrogen intrusion surface is not particularly limited as long as it can block the corrosive environment. As a specific method, a stainless steel foil is attached by an organic-based adhesive or the like.

As described above, in the present invention, it is possible to be independent of environmental changes such as temperature changes. The amount of hydrogen that invades the inside of the metal accompanying the corrosion is accurately detected.

Therefore, when the measuring device of the present invention is attached to a moving body such as an automobile, a ship, or a railway vehicle, the respective portions of the metal material constituting the moving body can be continuously and accurately prevented from being affected by changes in the environment exposed in the state of use. Monitor the amount of hydrogen that invades into the metal material.

As a result, regarding various moving bodies, it is possible to accurately determine whether or not the amount of hydrogen intrusion due to corrosion in the actual use environment is delayed.

However, in the various studies conducted repeatedly using the apparatus of the present invention, it was found that under the conditions of simulating the winter corrosive environment, there was a case where the solution leaked from the inside of the unit.

Therefore, as a result of investigating the cause of leakage of the above solution, it is clear that the reason is that the internal solution freezes at a low temperature to cause the solution to swell, thereby causing the cell to be broken.

In order to accurately monitor the amount of hydrogen inside the metal portion of the moving body which is a feature of the present invention, it is necessary to stably measure the amount of intrusive hydrogen accurately during winter traveling.

Therefore, the inventors of the present invention have conducted research on a device capable of stably measuring the amount of hydrogen intruding into the metal accompanying corrosion in the winter without causing damage to the cell due to freezing of the internal solution.

In the case of a driving environment in a town, it is considered that when the heat of the moving body is taken into consideration, the electrolyte inside the unit is less than -5 ° C. Therefore, it is considered that the freezing point temperature of the electrolytic solution is set to -5 ° C or less. can.

Therefore, as a result of a study in which the freezing point temperature of the electrolytic solution was set to -5 ° C or lower, it was found that an organic compound effective for lowering the freezing point can be added to the aqueous electrolyte solution.

Further, the organic compound is not particularly limited, but it is preferably isopropyl alcohol, glycerin or ethylene glycol. Further, it has been found that dimethyl sulfoxide (DMSO, Dimethylformamide) or dimethylformamide (DMFA) which is a polar solvent having low electrochemical activity is also suitable.

Here, the preferred addition ratio of such an organic compound is about 5 to 30% by volume. Further, the freezing point further decreases as the amount of addition increases.

These organic compounds are also filled with organic compounds in window washers and the like, and even if they leak out, they hardly adversely affect the environment.

Further, it has been found that by arranging the bubbles inside the unit, even if the unit is exposed to a temperature exceeding the intended low temperature environment, and the electrolytic solution is solidified, and the volume expansion of the electrolytic solution occurs, the unit body can be lightened by bubble contraction. damage. However, in this case, if the bubble is in contact with the hydrogen detecting surface, the detection sensitivity of the amount of invading hydrogen is lowered, which impairs the essential meaning of the present invention. Therefore, it is important to arrange the bubble system not with hydrogen. Check where the face is in contact.

The method of disposing the bubbles so as not to come into contact with the hydrogen detecting surface is not particularly limited. For example, a bag in which bubbles are placed may be disposed inside the unit, or may be provided as a unit as shown in FIGS. 4 and 5. Internal structure. In Figures 4 and 5, Reference numeral 11 is a bubble, 12 is an electrolytic solution, and 13 is an O-ring.

Further, the amount of the bubbles is not particularly limited. However, in consideration of volume expansion at the time of solidification of water, it is preferable to set the volume ratio to about 5 to 15% of the solution. Since oxygen is present in the bubbles, the anode reaction of the hydrogen detecting surface is affected, and therefore the type of the bubbles is preferably an inert gas.

[Examples] [Example 1]

The test was carried out using a measuring device having four units (CH1 to 4) having the structure shown in Fig. 2 . As the sample to be tested, a soft steel plate having a thickness of 1.0 mm in which Pd was plated to a thickness of 100 nm on the hydrogen detection surface side was used. The reference cell is channel 3 (CH3), and a stainless steel foil is attached as a protective film to a portion of the CH3 corresponding to the side of the etching surface. 300 mL of 0.5 M NaCl was added dropwise to the surface of the etched side of each unit, followed by drying at 25 ° C, 35% RH (relative humidity) for more than 4 hours, and then maintained at 25 ° C, 85% RH (relative humidity). After 24 hours or more, the temperature is gradually increased stepwise. The potential of the hydrogen detection surface was maintained at 0 V vs SCE. The temperature change and humidity change at this time are shown in Fig. 6.

Corresponding to the temperature change shown in Fig. 6, the change in the anode current density detected in each channel is shown in Fig. 7.

It can be seen that the anode current density value of the reference electrode (CH3) which was not corroded on the surface of the steel sheet also increased with an increase in temperature. The reason is considered to be that the residual current generated by the oxidation current of Pd on the hydrogen detecting surface side rises due to temperature. increase. Thus, the temperature dependence of the residual current is such an extent that it cannot be ignored.

A photograph of the appearance of the etched side of the sample after the test is shown in Fig. 8.

The reason why the anode current density value of 4Ch is smaller than that of the other Ch is that the position of the hydrogen intrusion surface side corresponding to the detection surface is small because the position of the 0.2 M NaCl initially dropped is shifted.

Therefore, if the anode current density values obtained from CH1 and CH2 are respectively subtracted from the anode current density values of the reference electrode (CH3), the accurate permeation hydrogen current density values in the respective units (CH1, CH2) can be obtained, and The permeation hydrogen current density value of the steel sheet of the test object can be obtained by obtaining the average value of the equivalent values.

Further, as described above, the amount of permeation hydrogen (intrusion amount of hydrogen) was calculated from the obtained permeation hydrogen current density value by the following formula.

In this way, an accurate permeation hydrogen current value or even a permeation hydrogen amount (intrusion amount of hydrogen) can be detected regardless of the temperature change.

The conversion of the amount of permeate hydrogen is based on the following formula.

Permeation hydrogen current density i _H (mA/cm ² = 10 ^-6 A/cm ² )

Permeate hydrogen per unit area M _H (mol/scm ² ), m _H (pieces/scm ² )

M _H =i _H ×1.036×10 ^-11 (mol/scm ² ),

m _H =i _H ×6.24×10 ¹² (pieces/scm ² )

[Embodiment 2]

The measuring device used in the first embodiment is actually mounted on an automobile, and a measuring system as schematically shown in Fig. 9 is constructed. 4-channel unit setting section The position is set to a) fender, b) indoor, c) under the floor (below the floor). A battery-driven multi-channel potentiostat is fabricated and stored in a box together with a dedicated battery. The test material was set to the same soft steel plate with a thickness of 1.0 mm as in Example 1, 5 days from Monday to Friday, and 6 hours from 9:00 to 15:00 per day in the area of the ironworks. Travel at an average speed of 40 km/h. Furthermore, it is parked in the parking lot from 15:00 to 9:00 the next day.

Regarding the maximum value of the anode current density detected in the period, the correction based on the reference electrode is taken as an example of the invention, and the case where the correction is not performed is taken as a comparative example, and is comparatively shown in FIG.

During the initial 5 days after the test piece was mounted, almost no corrosion occurred in each portion. As shown in Fig. 10, the difference in the anode current density of the inventive example was not observed due to the set portion. On the other hand, in the comparative example, the difference in anode current density due to the installation portion was observed. Therefore, the difference is considered to be the difference between the portion where the temperature rises due to the daytime sunshine (the fender) and the portion where the temperature hardly rises (under the floor) depending on the location of the installation.

It can be known that the measured anode current density value is corrected according to the present invention according to the present invention, and an accurate anode current density value (permeation hydrogen current density value) can be obtained without being affected by the temperature change.

[Example 3]

The steel sheets used were subjected to shear processing to 40 × 50 mm using a commercially available soft steel sheet (thickness: 0.8 mm), and the both surfaces were polished to #2000. Following Further, in order to remove the processed layer formed during polishing, chemical etching was performed on both sides by an aqueous solution containing a mixture of hydrofluoric acid and hydrogen peroxide water.

(plating on the hydrogen detection surface)

Pd plating of about 100 mm was performed on a hydrogen detection surface using a commercially available K-pure palladium plating solution (manufactured by Kojima Chemical Co., Ltd.).

(aqueous electrolyte solution in the unit)

As the aqueous electrolyte solution, dimethyl hydrazine (DMSO) was added to a 0.1 N aqueous sodium hydroxide solution at various ratios, and the freezing point in each case was measured.

(Structure of the unit on the side of the detection side)

When the structure including two elements shown in Fig. 11 is used, the structure corresponding to the portions of 7a and 7b is changed as follows.

Structure A: The electrolyte was filled without containing bubbles in the configuration shown in FIG.

Structure B: The structure shown in Fig. 5 was used, and the amount of bubbles was set to 15 vol% of the volume of the electrolytic aqueous solution, and the bubbles were sealed with nitrogen.

The steel sheet is placed in a unit as the above structure in the manner shown in FIG. The reference electrode was an Ir/IrO _X electrode, and the Pt line was placed on the opposite electrode and the potential was set to 0 V to arrange the cell in a corrosive environment.

The non-corrosive unit for correcting the temperature change is provided by disposing an epoxy resin and a stainless steel foil on one channel of the unit.

The above units are mounted on a commercially available rider in the ironworks from 2011. It will run for 15 days from January 18th to February 2nd. The lowest temperature change during the period according to HP (Home Page, Homepage) is shown in Figure 12. Further, in order to prevent leakage of the content liquid due to freezing, the bag is covered after the surface of the corroded steel sheet is covered.

The date on which the unit breakage or the electrolytic solution leaked out during the period is shown in Table 1. Further, Table 1 shows the maximum value of the current density obtained in each period and the maximum value of the current density corrected in accordance with the present invention.

Further, after the end of the period, the units of No. 2 and No. 4 were placed in a freezing tester set at -20 ° C in the test chamber, and the damage state of the unit was examined, and the results are also shown in Table 1.

According to the results of Table 1, the following cases are known.

No. 1 is a comparative example in which only an aqueous sodium hydroxide solution is used as the electrolytic solution. However, it was confirmed on January 27 that the electrolyte leaked due to breakage of the cell, and No. 2 to No. 4 as the invention examples were not confirmed. Damage to the unit.

In addition, in the period 1, it was confirmed that there was almost no evidence of corrosion on the surface of the steel sheet, so that the intrusion of hydrogen into the steel sheet due to corrosion was not observed, and the current value could not be detected, but it was found that the temperature correction was not performed. And a relatively large current value is detected. The reason for this is considered to be a change in the residual current due to a change in temperature, and it can be understood that the temperature change can be removed by performing temperature correction according to the invention.

Further, when No. 2 to No. 4 to which dimethyl hydrazine (DMSO) was added was compared with No. 1 which was not added, since the difference in current value was not confirmed, it was found that dimethyl hydrazine was added (DMSO). ) does not affect the accuracy.

In the period 2 and the period 3, it was confirmed that there was corrosion of the steel sheet on the road surface, and it was confirmed that there was an increase in the current density corresponding thereto. However, it was found that the amount of hydrogen generated by the corrosion and invaded into the steel sheet can be monitored. .

Further, in the case of maintaining a low temperature environment of -20 ° C, damage was confirmed in the unit No. 2. On the other hand, in the case of the unit No. 4 in which the air bubbles were disposed inside, it was confirmed that there was a freeze, but the damage of the unit was not confirmed. From this, it can be seen that it is confirmed that the air bubbles are disposed inside the unit, and the damage can be suppressed even if the temperature exceeds the set temperature.

(industrial availability)

According to the present invention, with respect to a moving body whose environment is constantly changing, it is possible to continuously and accurately monitor the amount of hydrogen which is generated by the corrosion-exposed environment in which the respective portions of the metal material constituting the corrosion is exposed and intruded into the metal material.

1a, 1b‧‧‧ electrolytic cell

2‧‧‧ samples

3a, 3b‧‧‧ reference electrode

4a, 4b‧‧‧ electrodes

4a, 4b‧‧‧ opposite electrode

5‧‧‧Sintered glass powder

6‧‧‧Tested object (steel plate)

Units 7a, 7b, 7c, 7d‧‧

7a‧‧‧Base unit

8‧‧‧relative electrode

9‧‧‧ reference electrode

10‧‧‧Protective film

11‧‧‧ bubbles

12‧‧‧ electrolyte

13‧‧‧O-ring

CH1, CH2, CH3, CH4‧‧‧ channels

T‧‧‧temperature

RH‧‧‧ Relative humidity

Figure 1 is an explanatory diagram of an electrochemical hydrogen permeation method.

Fig. 2 is a view schematically showing an example of a measuring apparatus of the present invention.

Fig. 3 is a view schematically showing the reaction at the side of the etching surface (hydrogen intrusion surface) and the side of the hydrogen detecting surface of the unit without the protective film.

Fig. 4 is a view showing an example of arranging bubbles inside a unit in accordance with the present invention.

Fig. 5 is a view showing another example of arranging bubbles inside the unit in accordance with the present invention.

Fig. 6 is a graph showing changes in temperature and humidity in the examples.

Fig. 7 is a graph showing the temporal change of the anode current detected in each channel.

Figure 8 is a photograph of the appearance of the etched side of the sample after the test.

Fig. 9 is a view schematically showing a measurement system when an anode current is measured by mounting a measuring device in an automobile.

Fig. 10 is a graph showing the difference in anode current density measured in each part of the automobile when the correction is performed by the reference electrode of the present invention (invention example) and when the correction is not performed (comparative example). Figure.

Fig. 11 is a view schematically showing another example of the measuring device of the present invention.

Fig. 12 is a graph showing the change in the minimum temperature during the measurement period.

6‧‧‧Tested object (steel plate)

7a‧‧‧ unit (reference unit)

Units 7b, 7c, 7d‧‧

8‧‧‧relative electrode

9‧‧‧ reference electrode

10‧‧‧Protective film

Claims (5)

An apparatus for measuring the amount of hydrogen intruding into a metal, which is an apparatus for measuring the amount of hydrogen generated by the corrosion of the object formed of a metal material and intruding into the metal by an electrochemical hydrogen permeation method, and is characterized in that: When the surface on one side of the object is exposed to a corrosive environment as an intrusion surface of hydrogen generated by a corrosion reaction, and the other side is a hydrogen detection surface, the hydrogen detection surface is used. An electrochemical element composed of a plurality of cell groups is disposed on the side, and each of the cells of the cell group is filled with an electrolyte aqueous solution having a pH of 9 to 13, and separate reference electrodes and opposite electrodes are disposed in the electrolyte aqueous solution. An organic compound for preventing freezing is added, and at least one unit of the unit group is used as a reference unit for correcting a residual current, and is disposed in an area of a hydrogen intrusion surface side of the reference unit corresponding to the hydrogen detection region. The protective film that is in contact with the corrosive environment is corrected for the yang detected by the unit other than the reference unit based on the residual current value detected by the reference unit Current value, based on the anode current value of this sum is calculated by correcting the amount of the hydrogen side of ingression. The apparatus for measuring the amount of hydrogen intrusion into the metal according to the first aspect of the patent application, wherein the organic compound added to the aqueous electrolyte solution is isopropanol, glycerin or ethylene glycol, or dimethyl hydrazine or dimethyl Formamide. An apparatus for measuring the amount of hydrogen intruding into a metal as in the first or second aspect of the patent application, wherein an Ir/Ir oxide electrode is used as the reference electrode. The apparatus for measuring the amount of hydrogen intrusion into the metal according to the first or second aspect of the patent application, wherein the inside of the electrochemical element filled with the aqueous electrolyte solution is disposed so as to avoid the contact with the hydrogen detecting surface. In the apparatus for measuring the amount of hydrogen intrusion into the metal according to the third aspect of the patent application, the inside of the electrochemical element filled with the aqueous electrolyte solution is disposed so as to avoid the contact with the hydrogen detecting surface.