Environment sensor and environment evaluation system

Abstract

To provide an environment sensor enabling state of environment or metal which is evaluation-target to be accurately recognized.SOLUTION: An environmental sensor (S) of the present invention comprises: a standard electrode (1) made of metallic silver and silver chloride; a reference electrode (2) made of metal and showing a potential change different from that of the standard electrode in accordance with a chloride ion concentration; and an insulator (4) which holds the standard electrode and reference electrode in such a manner that they are separated from each other. The environmental sensor can detect a first potential difference (ΔV1) between a standard electrode and a reference electrode which are exposed to a test environment. Further, an environmental sensor provided with a sample electrode made of a test-target metal can be used to detect a second potential difference (ΔV2) between the standard electrode or reference electrode and the sample electrode. Chloride ion concentration of the test environment can be determined based on the first potential difference. By identifying the potential of the sample electrode from the second potential difference, the state of the test-target metal can be accurately recognized.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an environmental sensor or an environmental evaluation system used for evaluating an environment or the like. [Background technology]

[0002] Metal members exposed to an environment such as the atmosphere may corrode or deteriorate. In order to grasp such processes and conditions, for example, a corrosion sensor is used that detects the corrosion current (galvanic current) flowing between a noble metal and a base metal. A well-known example is an atmospheric corrosion monitor or galvanic corrosion sensor (ACM: Atmospheric Corrosion Monitor) in which a conductive layer (Ag, etc.) is laminated on a substrate made of a sample metal (Fe, Zn, etc.) via an insulating layer (SiO2, etc.). A corrosion current occurs when a noble metal and a base metal are connected (short-circuited) by a water film, condensation, etc., and the environment and metal conditions can be grasped by detecting the corrosion current. The following patent documents contain related descriptions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 11-237358 (Patent No. 3875789) [Patent Document 2] Patent Publication No. 2018-105667 [Patent Document 3] Patent Publication No. 2020-165749 (Patent No. 7032349) Summary of the Invention [Problem to be solved by the invention]

[0004] In the sensor of Patent Document 1 or Patent Document 2, a noble metal (particularly a metal with a positive standard potential) disposed in close proximity to a measured member made of a less noble metal may promote corrosion of the measured member.

[0005] In Patent Document 3, the corrosion of a metal surface is detected by measuring the potential difference between the metal surface to be evaluated and a silver electrode (reference electrode) disposed on the metal surface via an insulating layer (

[0054] to

[0056] ). However, the potential of the silver electrode itself is determined by the chloride ions (Cl - ) concentration, etc., so the condition of the metal surface cannot be accurately evaluated by detecting only such a potential difference.

[0006] The present invention has been made in view of the above circumstances, and provides a new environmental sensor etc. that can be used for accurate evaluation of the environment and metals. [Means for solving the problem]

[0007] As a result of intensive research into solving this problem, the inventor came up with the idea of ​​accurately grasping the chloride ion concentration in the environment to which different metal electrodes are exposed and the state of the metal in such an environment from the potential difference between those electrodes, and realized this idea, and further developed it to complete the present invention described below.

[0008] <Environmental Sensor> (1) The present invention provides an environmental sensor that includes, for example, a reference electrode made of metallic silver and silver chloride, a reference electrode made of a metal and exhibiting a different potential change from that of the reference electrode in accordance with chloride ion concentration, and an insulator that holds the reference electrode and the reference electrode at a distance, and that can output a first potential difference that is the potential difference between the reference electrode and the reference electrode in a test environment to which the reference electrode and the reference electrode are exposed.

[0009] The environmental sensor (also simply referred to as "sensor") of the present invention can measure a potential difference (first potential difference) that may occur between a standard electrode and a reference electrode, at least a portion of which is exposed to the environment to be evaluated (test environment).

[0010] Because the standard electrode and the reference electrode have different potential changes in response to chloride ion concentration, the first potential difference reflects the chloride ion concentration in an environment to which at least a portion of each electrode is exposed. Thus, measuring (measuring, detecting, etc.) the first potential difference allows for identification or quantification of the chloride ion concentration in the environment.

[0011] Incidentally, chloride ions (especially chlorine ions) are the main corrosion factor for metals in wet environments where liquids (water films, water droplets, etc.) may adhere. For this reason, the presence or absence of chloride ions and their concentration (especially [Cl - Identifying the corrosion and deterioration environments of metal components is useful for understanding the corrosion and deterioration environments of metal components.

[0012] (2) The present invention may also be an environmental sensor further comprising a sample electrode made of a test metal, the insulator holding the sample electrode at a distance from the reference electrode and the reference electrode, and capable of outputting a second potential difference which is the potential difference between the reference electrode or the reference electrode and the sample electrode.

[0013] According to the sensor of the present invention, in addition to the above-mentioned first potential difference, it is also possible to measure a potential difference (second potential difference) that may occur between the sample electrode and the standard electrode or reference electrode in the test environment, thereby making it possible to grasp the state of the metal to be evaluated (test metal) in the test environment.

[0014] Furthermore, since the sensor of the present invention requires only a simple structure of different metal electrodes held together by an insulator, it is possible to expand the range of application and ensure stable output over the long term by making it smaller and reducing (eliminating) maintenance.

[0015] Environmental Evaluation System The present invention can also be understood as a system using the above-mentioned sensor. For example, the present invention may be an environment evaluation system (also simply referred to as a "system") including the above-mentioned environment sensor, a measuring means for measuring an output of the environment sensor, and a concentration determining means for determining a chloride ion concentration in the test environment based on the first potential difference.

[0016] In addition, if the environmental sensor includes a sample electrode made of a test metal, the system of the present invention may also include a potential determining means for determining a sample potential, which is the potential of the sample electrode, based on the second potential difference. This potential determining means may correct the sample potential based on the chloride ion concentration.

[0017] Furthermore, the system of the present invention may be equipped with a recording means for recording the sample potential and chloride ion concentration over time, and a means for determining and evaluating the state of the test metal (e.g., the corrosion state) based on the changes over time in the sample potential and chloride ion concentration.

[0018] "others" (1) In this specification, "means" may be read as "step." As a result, the present invention may be understood as an environmental evaluation method, etc. Each means (step) according to the present invention may be constituted by a computer or a program executed by the computer, in addition to relying on a dedicated measuring device or recording device, etc.

[0019] (2) Unless otherwise specified, "x to y" in this specification includes a lower limit of x and an upper limit of y. Any numerical value included in the various numerical values ​​or numerical ranges described in this specification may be used as a new lower limit or upper limit to create a new range such as "a to b." [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram illustrating an environmental sensor and an environmental evaluation system. [Diagram 2] 1 shows a schematic diagram and an actual photograph of the test sensor that was fabricated. [Figure 3A] 1 is a graph showing the relationship between NaCl concentration and the potential of a reference electrode (Ag / AgCl). [Figure 3B] 1 is a graph showing the relationship between the NaCl concentration and the potential of the reference electrode (Zn). [Figure 3C] 1 is a graph showing the relationship between NaCl concentration and the potential of a reference electrode (Mg). [Figure 3D]FIG. 1 is a scatter plot showing the relationship between the NaCl concentration and the potential of the sample electrode (Al alloy). [Figure 4] 1 is a graph showing the relationship between the NaCl concentration and the first potential difference (Zn vs. Ag / AgCl). [Diagram 5] 13 is a graph showing the relationship between the state of the sample electrode (test metal) and the second potential difference (Al vs. Ag / AgCl). [Figure 6] FIG. 13 is a schematic diagram showing a modified example of the environmental sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] One or more components selected arbitrarily from this specification may be added to the above-mentioned components of the present invention. The contents described in this specification may be appropriately applied not only to the environmental sensor and environmental evaluation system of the present invention, but also to the environmental evaluation method and the like. Which embodiment is best depends on the target, required performance, etc.

[0022] <Environmental Sensor> The environmental sensor includes at least a reference electrode, a reference electrode, and an insulator, and may further include a sample electrode. The electrodes are arranged so as not to be short-circuited by the insulator. However, at least a portion of each electrode is exposed to the test environment. Therefore, ion conduction is possible between the electrodes in contact with the electrolyte (water film, water droplets, etc.).

[0023] The form (shape, size) of each electrode is not important. It may be needle-shaped, rod-shaped, columnar, plate-shaped, foil-shaped, etc., and its cross section may be (elliptical), polygonal, rectangular, etc. Each electrode is made of metal. In this specification, "metal" or "substrate" includes pure metal (purity 99% or more) as well as alloy, unless otherwise specified. The amount of elements other than the main component contained in the alloy is preferably less than 10% (main component element is 90% or more, 95% or more, or even 98% or more). In this specification, composition and concentration (%) mean mass percentage (mass%, wt%) relative to the whole, unless otherwise specified.

[0024] Each electrode is electrically connected to an external circuit (such as a measuring device) by wiring such as a terminal or lead. Details of each electrode are as follows.

[0025] (1)Reference electrode The reference electrode is made of metallic silver and silver chloride (Ag / AgCl). The silver chloride does not necessarily have to cover the entire surface of the metallic silver. Ag / AgCl is, for example, - This can be obtained by electrolysis using Ag as the anode in a solution containing Ag (such as an aqueous KCl solution). Ag / AgCl is a non-polarizable electrode, and shows a stable electrode potential (E). However, as shown in the Nernst equation, the electrode potential (E) varies according to the chlorine (chloride) ion concentration (activity), as shown in the standard electrode potential (E 0 ) to cause a negative shift.

[0026] The "reference electrode" according to the present invention is not immersed in a saturated KCl aqueous solution (containing AgCl) in which Ag / AgCl is contained in a glass tube. In this respect, it differs from reference electrodes generally used in electrochemical measurements of three-electrode systems. This also applies to "reference electrodes" and the like.

[0027] (2)Reference electrode The reference electrode is made of a metal that exhibits a change in potential according to the chloride ion concentration, and the change in potential (pattern) is different from that of the standard electrode (Ag / AgCl). For example, the chloride ion (Cl - It is preferable that the rate of change (slope) of the electrode potential (E) with respect to the concentration (including activity) of the reference electrode be different from that of the standard electrode.

[0028] This makes it possible to obtain the chloride ion concentration in the test environment from the potential difference (first potential difference) between the two electrodes. If the first potential difference changes monotonically with respect to the chloride ion concentration (particularly monotonically increasing or decreasing), it becomes easy to quantify the chloride ion concentration. Although a single reference electrode is sufficient, multiple reference electrodes may be used.

[0029] Such reference electrodes are made of, for example, Zn or Mg substrates. The standard electrode potential of Ag / AgCl (E 0: 0.222V (>0), the standard electrode potential of Zn (E 0 ):-0.762V(<0), standard electrode potential of Mg (E 0 ): −1.55 V (<0). By using such a metal electrode, the first potential difference (ΔV1) can be made large.

[0030] Since the electrode potential of a Zn substrate or Mg substrate is basically negative, even if the substrate is placed near a less noble test metal (such as an Al substrate), the progress of corrosion of the test metal is suppressed.

[0031] (3) Sample electrode The sample electrode is made of the metal to be evaluated (test metal). Test metals vary depending on the product or component, and are, for example, Al-based, Fe-based, Ti-based, Mg-based, etc. The test metal may be any of cast materials, wrought materials, sintered materials, etc., regardless of its manufacturing process.

[0032] The test metal may be one that forms a passive film (coating, film) on its surface, such as an Al substrate, a Ti substrate, stainless steel, etc. By measuring the potential difference (second potential difference: ΔV2) between the sample electrode and the standard electrode or reference electrode, it becomes possible to grasp the surface condition of the test metal (presence or absence of corrosion, generation of a passive film, defects or recovery, etc.).

[0033] The sample electrode may be a separate electrode prepared specifically for the environmental sensor, or may be a part of a product or component (such as a housing or structure). For example, a standard electrode and a reference electrode may be placed on the metal surface of the actual product (product) via an insulator to form an environmental sensor as a whole.

[0034] (4) Insulator The insulator holds the electrodes apart. The insulator may be in the form of a layer, a block, etc. The insulator may be, for example, an insulating resin (such as an epoxy resin), ceramics, paper, or the like.

[0035] The insulator is sufficient if it can keep the electrodes in a non-conductive state in a completely dry environment. In a humid environment, it may be in a conductive state between the electrodes. For this reason, the insulator is not limited to a dense body, and may be a porous body (such as a sponge or filter) that has air permeability and liquid permeability (moisture retention and water retention).

[0036] Environmental Evaluation System In addition to the environmental sensor, the environmental evaluation system at least comprises a measuring means for measuring the output (including zero) of the environmental sensor. The system may also comprise a concentration determining means for determining the chloride ion concentration from the potential difference (first potential difference) between the standard electrode and the reference electrode, and a potential determining means for determining the potential of the sample electrode (sample potential) based on the potential difference (second potential difference) between the sample electrode and the standard electrode or the reference electrode. The components of such a system are described in detail below.

[0037] (1)Measurement means The output (potential difference) of the environmental sensor is measured, for example, by a voltmeter. A potentiostat, a computer, or the like may also be used as the measuring means.

[0038] (2) Concentration identification means The concentration determination means is, for example, the chloride ion concentration (mainly Cl) in the environment to which the standard electrode and the reference electrode are exposed. - The data storage device is composed of a database (e.g., a calibration curve) indicating the relationship between the chloride ion concentration (chloride ion concentration) and the potential difference (first potential difference) between the electrodes, and a processing program that specifies (extracts, selects, calculates, etc.) the chloride ion concentration corresponding to the first potential difference based on the database.

[0039] (3) Potential identification means The potential determining means determines the potential of the sample electrode made of the test metal (sample potential) based on the potential difference (second potential difference) between the sample electrode and the standard or reference electrode. If the test environment is substantially constant or its state is known, the potential difference may be directly used as the sample potential and used as an index of the state of the test metal.

[0040] If the test environment (especially the chloride ion concentration) is unknown or fluctuates, the sample potential may be corrected according to the chloride ion concentration determined by the concentration determination means. - Once the concentration (activity) is known, the potential of the base standard electrode (reference potential) or the potential of the reference electrode (reference potential) can be identified (extracted, selected, calculated, etc.) based on a previously prepared database or the Nernst equation.

[0041] By adding the second potential difference to such a base potential (a standard potential or reference potential calibrated taking into account the chloride ion concentration), a corrected sample potential can be obtained. In this manner, the potential determining means may include a correcting means for calibrating the sample potential in accordance with the chloride ion concentration.

[0042] (4) Recording means The chloride ion concentration in the test environment obtained by the concentration determination means, the sample potential obtained by the potential determination means, etc. may be recorded over time (recording means). This allows the conditions of the test environment and the test metal to be observed over a long period of time, and their changes can be accurately understood.

[0043] The recording means is, for example, a data logger, but a computer storage device (memory, HDD, etc.) may also be used. EXAMPLES

[0044] Environmental Evaluation System A schematic diagram of an environmental evaluation system M according to one embodiment of the present invention is shown in Fig. 1. The environmental evaluation system M includes an environmental sensor S and a measurement and analysis device D. The environmental sensor S includes a reference electrode 1, a reference electrode 2, a sample electrode 3, and an insulating layer 4 interposed between the sample electrode 3 and the reference electrode 1 and between the sample electrode 3 and the reference electrode 2.

[0045] The reference electrode 1, the reference electrode 2 and the sample electrode 3 are electrically connected to a measurement and analysis device D by leads 11, 21 and 31 from their respective terminals.

[0046] Measurement and analysis device D measures the potential difference (ΔV1: first potential difference) between reference electrode 1 and reference electrode 2, and the potential difference (ΔV2: second potential difference) between reference electrode 1 and sample electrode 3 (potential measuring means).

[0047] The measurement and analysis device D is, for example, a computer connected to the environmental sensor S via an interface. The measurement and analysis device D processes the input (potential difference) from the environmental sensor S according to a previously prepared program. For example, the measurement and analysis device D displays the input (ΔV1, ΔV2) over time on a display, and identifies (calculates) environmental information (chloride ion concentration, etc.) in which the environmental sensor S is located by comparing the input with a stored database, and identifies (calculates) the potential of the sample electrode 3 (sample potential) taking into account the chloride ion concentration.

[0048] Test Example (1) Environmental Sensor Test sensor T shown in Figure 2 was actually produced. The specifications of test sensor T are as shown in Figure 2. A pure silver wire with commercially available silver chloride paste attached was used as the reference electrode. Two types of reference electrodes were prepared: a plate (reference electrode I) made of metal Zn (purity 99.2%) and a wire (reference electrode II) made of metal Mg (purity 99.95%). A plate made of Al alloy (JIS A5052) was used as the sample electrode.

[0049] An insulating layer made of epoxy resin was provided between the sample electrode and the reference electrode I and II. The reference electrode was placed apart from the other electrodes, and the whole was embedded in insulating epoxy resin. The insulating layer and the embedding resin correspond to the insulator in the present invention.

[0050] One side of the short cylindrical molded body molded with the embedding resin was polished to expose the end faces of each electrode flush. The wiring for each electrode was provided on the other side of the molded body (the back side in Figure 2).

[0051] (2) Effect of chloride ion concentration The influence (dependence) of the electrode potential on the chloride ion concentration was investigated as follows. Based on the potential of a commercially available KCl saturated Ag / AgCl electrode (HX-R6 manufactured by Hokuto Denko Corporation), the potential (E) of each electrode of the test sensor T immersed in an aqueous NaCl solution was measured. In this case, the concentration of the aqueous NaCl solution was either 0.3%, 0.5%, 1%, 3%, 5% or 10%. A potentiostat was used to measure the potential (potential difference).

[0052] The relationship between the obtained electrode potential and the NaCl concentration of the aqueous solution is shown in Figures 3A to 3D (collectively referred to as "Figure 3"). Note that the horizontal axis of each figure is the natural logarithm of the NaCl concentration.

[0053] As shown in Figures 3A to 3C, the chloride ion concentration (Cl - As the concentration of NaCl increased, the potential shifted almost linearly to the less noble side. For reference, the approximate equation showing the relationship between the potential (y) and the NaCl concentration (x) is also shown in each figure.

[0054] On the other hand, as shown in Figure 3D, no regularity was observed between the potential of the sample electrode (Al alloy / A5052) and the NaCl concentration. This is thought to be due to the influence of the oxide film (passivation film) formed on the electrode surface.

[0055] (3) First potential difference and chloride ion concentration Based on the results shown in Figures 3A to 3C, the potential difference (first potential difference: ΔV1) between the standard electrode (Ag / AgCl) and the reference electrode I (Zn) was measured using the test sensor T immersed in the above-mentioned NaCl aqueous solution. At this time, the concentration of the NaCl aqueous solution was either 0.5%, 1%, 5% or 10%. The relationship between the first potential difference thus obtained and the NaCl concentration is shown in Figure 4. The horizontal axis of Figure 4 is also the natural logarithm of the NaCl concentration.

[0056] As is clear from Figure 4, the potential difference (ΔV1) between the standard electrode and reference electrode I increases with the chloride ion concentration (Cl -The potential (y) increased monotonically with increasing NaCl concentration (x). For reference, the approximate equation showing the relationship between the potential (y) and the NaCl concentration (x) is also shown in FIG.

[0057] If a calibration curve (database) like that shown in Figure 4 is prepared in advance, the chloride ion concentration (Cl - It was found that it is possible to quantify (identify) the concentration of a substance (a means of identifying the concentration).

[0058] Incidentally, as shown in Figures 3A and 3B, the potential change of each electrode decreases monotonically with respect to the chloride ion concentration. However, the potential change of the standard electrode is smaller than the potential change of reference electrode I. Therefore, the first potential difference (ΔV1) obtained as the difference between them increases monotonically with respect to the chloride ion concentration, as shown in Figure 4. The reason why the approximation formula shown in Figure 4 is not a simple difference of the approximation formulas shown in Figures 3A and 3B is thought to be due to the influence of individual differences in the Zn metal surface. For this reason, it is preferable to prepare a calibration curve for each environmental sensor fabricated.

[0059] (4) Monitoring of test metals The test sensor T was immersed in an aqueous NaCl solution (7%), and the potential difference (second potential difference: ΔV2) of the sample electrode relative to the reference electrode was measured, and the change over time was monitored (recording means). During this process, the surface of the sample electrode was scratched (around 400 s). After that, hydrogen peroxide water (oxidizing agent) was added (around 700 s). As a result, the potential difference (sample potential) of the sample electrode (test metal) relative to the reference electrode changed as shown in Figure 5.

[0060] As is clear from Figure 5, the sample potential was stable when the test sensor T was first immersed in the NaCl solution. However, due to scratches on the surface of the sample electrode, the potential shifted significantly to the negative side. This is thought to be because the oxide film (passivation film) on the electrode surface was scraped off, and dissolution (corrosion) occurred from the newly formed surface of the Al base material.

[0061] After that, the sample potential gradually returned to the noble side, and after the addition of the oxidizing agent, the sample potential shifted sharply to the noble side, and then returned to the initial stable potential. From this process, it was found that the state of the metal surface (e.g., passivation, corrosion, etc.) is greatly reflected in the potential (evaluation step).

[0062] (5) Supplementary Information In this test example, we have shown the case where the chloride ion concentration (NaCl aqueous solution concentration) is known. If the concentration is unknown, for example, the chloride ion concentration can be estimated by applying the measured potential difference (ΔV1) between the standard electrode and the reference electrode to a calibration curve (database) as shown in Figure 4 (concentration determination step).

[0063] If the concentration is known, the potential of the reference electrode (vs. Ag / AgClSat. KCl) at that time can be estimated by using a calibration curve (database) as shown in Figure 3 A. If the potential difference (ΔV2) of the sample electrode with respect to the reference electrode is corrected based on this potential, the potential of the sample itself (vs. Ag / AgClSat. KCl) can also be estimated (potential determination step / potential correction step).

[0064] In this way, even when the state of the test metal is in a test environment where the chloride ion concentration is unknown or fluctuating, it is possible to accurately grasp the state by using a potential based on a constant base potential (vs. Ag / AgClSat. KCl).

[0065] From the above, it has been confirmed that the sensor and system of the present invention can accurately grasp the state of the environment and metal being evaluated.

[0066] Incidentally, the standard electrode, the reference electrode, and the sample electrode may be disposed together (integrated) (see FIG. 2), or may be disposed separately. For example, as shown in FIG. 6, a sensor may be used in which a pair of a standard electrode and a reference electrode (I, II) or a pair of a standard electrode and a sample electrode are held apart by an insulator (embedding resin, epoxy resin, etc.). Each sensor may be used individually or in combination. For example, a sensor in which a standard electrode and a reference electrode are held by an insulator may be used to identify the chloride ion concentration in the environment. Furthermore, the sensor may be combined with a sensor in which a standard electrode and a sample electrode are held by an insulator to grasp the state of the test metal in the test environment. By using a sensor in which at least a pair of electrodes are held by an insulator, the interchangeability and combinability of the sensor are improved. [Explanation of symbols]

[0067] 1 Reference electrode 2 Reference electrode 3. Sample Electrode 4. Insulation layer (insulator) M Environmental Evaluation System S Environmental Sensor D Measurement analysis device

Claims

1. A reference electrode made of metallic silver and silver chloride; A reference electrode made of a metal and exhibiting a different potential change from that of the reference electrode according to the chloride ion concentration; an insulator that holds the reference electrode and the reference electrode apart; The environmental sensor is capable of outputting a first potential difference, which is a potential difference between the reference electrode and the reference electrode, in a test environment to which the reference electrode and the reference electrode are exposed.

2. 2. The environmental sensor of claim 1, wherein the first potential difference varies monotonically with respect to the chloride ion concentration.

3. The environmental sensor according to claim 1 , wherein the reference electrode is made of a Zn-based material or a Mg-based material.

4. Further, a sample electrode made of a test metal is provided, the insulator holds the sample electrode spaced apart from the reference electrode and the reference electrode; 2. The environmental sensor according to claim 1, which is capable of outputting a second potential difference which is a potential difference between the reference electrode and the sample electrode.

5. The environmental sensor according to claim 4 , wherein the sample electrode is made of an Al base material.

6. An environmental sensor according to any one of claims 1 to 3; A measuring means for measuring an output of the environmental sensor; a concentration determining means for determining a chloride ion concentration in the test environment based on the first potential difference; An environmental evaluation system comprising:

7. An environmental sensor according to claim 4 or 5; A measuring means for measuring an output of the environmental sensor; a concentration determining means for determining a chloride ion concentration in the test environment based on the first potential difference; a potential determining means for determining a sample potential, which is a potential of the sample electrode, based on the second potential difference; An environmental evaluation system comprising:

8. 8. The environment evaluation system according to claim 7, wherein the potential specifying means corrects the sample potential based on the chloride ion concentration.

9. 8. The environment evaluation system according to claim 7, further comprising a recording means for recording the sample potential and / or the chloride ion concentration over time.

Images