Environmental monitoring method and environmental monitoring device

Abstract

To obtain corrosion rates of various different types of metals with a simple configuration.SOLUTION: A method for monitoring an environment obtains a corrosion environment of a structure made of metal by measuring the output of a sensor which obtains an output between an anode and a cathod, and obtains the corrosion rate of the metal by using output data and moisture data of the sensor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to an environmental monitoring method and an environmental monitoring device for monitoring the atmospheric corrosion of structures exposed to the atmospheric environment.

Background Art

[0002] Structures exposed to the natural environment over a long period of time, such as bridges, signs, streetlights, floodgates, transmission towers, ships, automobiles, and eaves, are corroded by factors such as moisture, oxygen, corrosive gases, and salts present in the atmosphere. Therefore, it is necessary to regularly inspect the corrosion situation to maintain a predetermined durability. Thus, in order to grasp the corrosion situation of structures, corrosion measurement devices for measuring the corrosion environmental properties of structures have been developed.

[0003] For example, Patent Document 1 proposes an ACM sensor (Atmospheric Corrosion Monitor) using a so-called galvanic couple that measures the current value flowing due to the connection between two dissimilar metals via an insulating part when moisture present in the atmosphere connects the two metals. This ACM sensor is formed, for example, by cutting out a carbon steel plate as an anode and applying a cathode thereon via an insulating part. This ACM sensor can measure the corrosion environmental properties of a structure with high accuracy by measuring the current flowing between the anode and the cathode when moisture adheres between the galvanic couples.

[0004] Also, for example, Non-Patent Document 1 discloses the principle of the ACM sensor, the practical application of the ACM sensor, and various methods for evaluating the corrosivity of atmospheric environments using the sensor under the title of "How much is known about atmospheric corrosion? Using the ACM sensor".

[0005] Furthermore, as a means of obtaining the corrosive environmental properties of a structure, a method has been proposed in which measurement data is created based on output data from a corrosion monitoring sensor consisting of an ACM sensor and a temperature and humidity sensor, and the corrosion rate is evaluated based on the humidity data from the temperature and humidity sensor and the current data from the ACM sensor from the measurement data (Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-33470 [Patent Document 2] Patent No. 6812335 [Non-patent literature]

[0007] [Non-Patent Document 1] National Institute for Materials Science (NIMS) http: / / www.nims.go.jp / corrosion / ACM / cr.htm "How far have we learned about atmospheric corrosion? Using ACM sensors" [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Thus, various methods have been proposed to obtain the corrosive environment of a structure using a sensor that obtains the output of a corrosion current flowing between the anode and cathode. For example, in a method that evaluates the corrosion rate based on humidity data from a temperature and humidity sensor and current data from a sensor that measures galvanic current due to corrosion, the system for determining the amount of sea salt deposit from humidity and utilizing a database of sea salt deposit and metal corrosion rates is complex, and it is difficult to easily obtain the corrosion rates of various metals.

[0009] This invention was made to solve the problems of the conventional methods, and aims to provide an environmental monitoring method and an environmental monitoring device that can obtain the corrosion rates of various metals with a simple configuration.

Means for Solving the Problem

[0010] In order to solve the above problems and achieve the object, the present invention is configured as follows.

[0011] The invention according to claim 1 is an environmental monitoring method for obtaining the corrosion environmental property of a structure made of metal by using a sensor for obtaining an output between an anode and a cathode and measuring the output of the sensor, obtaining the corrosion rate of the metal by using the output data of the sensor and humidity data In environmental monitoring methods, The aforementioned sensor is an ACM sensor, The anode of the ACM sensor is made of zinc or a zinc alloy. When correcting the output data of the ACM sensor with humidity data to obtain the zinc corrosion rate, A linear relationship is obtained that defines the output of the ACM sensor and the corrosion rate of the zinc, wherein the gradient increases as humidity increases, and the zinc corresponding to the output of the ACM sensor in the linear relationship is obtained. characterized by obtaining the corrosion rate of.

[0013] Claim 2 The invention described in is characterized in that the ACM sensor has a cathode made of silver or carbon Claim 1 is the environmental monitoring method described in

[0014] Claim 3 The invention described in is an environmental monitoring device for obtaining the corrosion environmental property of a structure made of metal by using a sensor for obtaining an output between an anode and a cathode and measuring the output of the sensor, a temperature and humidity sensor for obtaining humidity data, a data unit for obtaining the output data of the sensor and the humidity data from the temperature and humidity sensor, a processing unit for obtaining the corrosion rate of the metal by using the output data and the humidity data, including In environmental monitoring devices , The aforementioned sensor is an ACM sensor, The anode of the ACM sensor is made of zinc or a zinc alloy. The data unit obtains the output data from the sensor and the humidity data from the temperature and humidity sensor, When the processing unit obtains the zinc corrosion rate using the output data and humidity data, A linear relationship is obtained that defines the output of the ACM sensor and the corrosion rate of the zinc, wherein the gradient increases as humidity increases, and the corrosion rate of the zinc corresponding to the output of the ACM sensor is obtained in the linear relationship. An environmental monitoring device characterized by the following.

[0016] Claim 4 The invention described in The ACM sensor is characterized in that the cathode is made of silver or carbon. Claim 3 It is the environmental monitoring device described in

Effect of the Invention

[0017] With the above configuration, this invention has the following effects.

[0018] In the invention described in claims 1 to 6, by using a sensor that obtains an output between an anode and a cathode and measuring the output of the sensor, the corrosive environmental property of a structure made of metal can be obtained. By using the output data of the sensor and the humidity data to obtain the corrosion rate of the metal, it is possible to obtain the corrosion rates of various metals with a simple configuration.

Brief Description of the Drawings

[0019] [Figure 1] It is a plan view of an environmental monitoring device. [Figure 2] It is a cross-sectional view of an environmental monitoring device. [Figure 3] It is a diagram showing the exposed state of an ACM sensor using the target metal. [Figure 4] It is a diagram for reading the output data of an ACM sensor and the humidity data at that time. [Figure 5] It is a diagram showing the correlation between the output of an ACM sensor and the corrosion rate. [Figure 6] It is a diagram showing the relationship between the outputs of an ACM sensor and an RCM sensor. [Figure 7] It is a diagram showing the ratio relationship between the corrosion amount of an RCM sensor and the electrical amount of an ACM sensor at different amounts of adhered salt. [[ID=K]] [Figure 8] It is a diagram showing the relationship between the output of an ACM sensor and the relative humidity, [Figure 9]This diagram shows the principle of the ACM sensor. [Figure 10] This figure shows the relationship between the daily average amount of Coulombs and the corrosion rate. [Figure 11] This diagram shows how the corrosion rate is calculated by formulating a mathematical equation based on the daily average of the electric coulomb quantity from the integrated output of the ACM sensor. [Figure 12] This diagram shows the relationship between the corrosion rate of iron (Fe) and the corrosion rate of zinc (Zn). [Figure 13] This figure shows the correlation between an ACM sensor with an iron (Fe) anode and an ACM sensor with a zinc (Zn) anode. [Figure 14] This formula allows us to determine the corrosion rate of zinc (Zn) from the coulombs / day of an ACM sensor with an iron (Fe) anode. [Figure 15] This is a diagram that verifies the validity of the present invention. [Modes for carrying out the invention]

[0020] The following describes embodiments of the environmental monitoring method and environmental monitoring device of this invention. These embodiments represent the most preferred form of the invention, and the invention is not limited thereto.

[0021] (Environmental monitoring device) The environmental monitoring device will be described based on Figures 1 and 2. Figure 1 is a plan view of the environmental monitoring device, and Figure 2 is a cross-sectional view of the environmental monitoring device.

[0022] The environmental monitoring device 10 of this embodiment is a device for monitoring atmospheric corrosion of structures exposed to the atmospheric environment, and is installed on structures that are exposed to the natural environment over a long period of time, such as bridges, signs, streetlights, sluice gates, power transmission towers, ships, automobiles, and culverts.

[0023] This environmental monitoring device 10 includes an ACM sensor 1 that obtains the output between the anode and cathode, a measuring meter 12 connected to the ACM sensor 1 via lead wires 11a and 11b to measure the output of the current between the anode 2 and cathode 3, a temperature and humidity sensor 13 that obtains humidity data, and a data logger 14. As a sensor that obtains the output between the anode and cathode, there are ACM sensors (Atmospheric Corrosion Monitors) that utilize so-called galvanic pairs, sensors that can measure current with dissimilar metals separated (see Japanese Patent Application Publication No. 2018-80984), etc., but in this embodiment, the ACM sensor 10 is used. As a sensor that obtains the output between the anode and cathode, an ACM sensor that outputs corrosion current is used, but it is also possible to use a sensor that utilizes a hydrogen storage alloy that releases hydrogen as an anode reaction other than corrosion.

[0024] This ACM sensor 1 has an anode 2 and a cathode 3, and is a sensor that obtains the output of current between the anode 2 and the cathode 3, with an insulating layer 4 interposed between the anode 2 and the cathode 3.

[0025] Anode 2 can be made of, for example, iron plate, galvanized steel plate, copper plate, zinc plate, aluminum plate, magnesium plate, tin plate, nickel plate, or chromium plate, and may be plated or alloyed. Cathode 3 can be made of silver, carbon, copper, gold, platinum, etc., and is formed by molding with resin paste or by lamination by sputtering or vapor deposition. For example, cathode 3 can be formed by screen printing a conductive paste onto the surface of insulating layer 4 and then heat curing it. Insulating layer 4 insulates anode 2 from cathode 3. In the ACM sensor 1, silver (Ag) is preferably used for cathode 3, as silver (Ag) is inexpensive and easy to manufacture among noble metals that do not corrode in corrosive atmospheric environments.

[0026] In this ACM sensor 1, moisture adheres to the galvanic couple due to atmospheric conditions such as rain, causing a current to flow between the anode 2 and cathode 3, and the output of this current is measured by the measuring instrument 12.

[0027] The data logger 14 comprises a data unit 14a and a processing unit 14b. The data unit 14a obtains output data from the ACM sensor 1 and humidity data from the temperature and humidity sensor 13, and the processing unit 14b uses the output data and humidity data to obtain the corrosion rate of the metal. The data unit 14a and the processing unit 14b comprise a data recording unit and a data calculation unit. In the data unit 14a, the output data from the ACM sensor 1 is corrected with the humidity data, and in the processing unit 14b, the corrosion rate of the metal is obtained based on the correction of the humidity data. In this way, by using the ACM sensor 1 which outputs a current that flows between the anode 2 and cathode 3 due to moisture, and correcting the output data from the ACM sensor 1 with humidity data, the corrosion rate of a structure made of metal can be determined, and the corrosion environment of the structure can be obtained. In one embodiment, the ACM sensor 1 is used, the anode of the ACM sensor 1 is made of zinc (Zn), the correction unit 14a corrects the output data from the ACM sensor 1 with humidity data from the temperature and humidity sensor 13, and the processing unit 14b can obtain the corrosion rate of zinc (Zn) based on the correction of the humidity data. Furthermore, the configuration includes a processing unit 14b that obtains the corrosion rate of other metals based on an estimation formula for the corrosion rate of iron (Fe).

[0028] (Principle for determining the corrosion rate of metals) Figure 3 shows the exposure conditions of an ACM sensor using the target metal. The ACM sensor has an insulating layer between the anode (iron) and cathode (silver). When moisture adheres to it due to atmospheric conditions such as rain, cathode current and anode current flow, and the output of this ACM sensor is measured with an ammeter.

[0029] Figure 4 shows the output data of the ACM sensor and the humidity data at that time. In Figure 4, the horizontal axis represents time, the left vertical axis represents the current value, and the right vertical axis represents relative humidity and temperature. As time passes, the current value, relative humidity, and temperature of the ACM sensor change, and the output of the ACM sensor and the humidity at that time are read. When moisture adheres to the ACM sensor due to atmospheric conditions such as rain, cathode current and anode current flow, and this output of the ACM sensor is measured with an ammeter.

[0030] Figure 5 shows the correlation between the output of the ACM sensor and the corrosion rate. In Figure 5, the horizontal axis represents the output of the ACM sensor, and the vertical axis represents the corrosion rate. The relationship between the output of the ACM sensor and the corrosion rate is such that the slope of the ACM sensor output changes with humidity. For example, in Figure 4, when the output of the ACM sensor is a current value of 0.01 μA, the relative humidity is 90% RH. From this, the corrosion rate can be calculated in Figure 5, and the corrosion rate shown by the triangle is obtained from the slope between the ACM sensor output of a current value of 0.01 μA and 90% RH, demonstrating the correlation between the output of the ACM sensor and the corrosion rate.

[0031] The relationship between the ACM sensor output and corrosion rate is explained by Figures 6 and 7, showing that the slope of the ACM sensor output changes with humidity, and this change is linear.

[0032] Figure 6 shows the relationship between the outputs of the RCM sensor and the ACM sensor. In Figure 6, the horizontal axis represents time, the left vertical axis represents the output of the ACM sensor, and the right vertical axis represents the output of the RCM sensor. The RCM sensor is an electrical resistance corrosion sensor that utilizes the electrical resistance of metal. The electrical resistance of a metal is determined by the type of metal, length, and cross-sectional area. Therefore, by measuring the electrical resistance value, the cross-sectional area can be determined, and the amount of wall thinning due to corrosion can be estimated.

[0033] The correlation between sensor output and corrosion rate was measured in advance for both the RCM and ACM sensors. The ACM sensor output is shown at relative humidity levels of 90%RH and 60%RH, and the RCM sensor output is also shown at relative humidity levels of 90%RH and 60%RH.

[0034] Figure 7 shows the relationship between the ratio of corrosion of the RCM sensor and the electrical output of the ACM sensor at a given amount of salt deposit. In Figure 6, the horizontal axis represents the relative humidity of the experimental environment, and the vertical axis represents the ratio of corrosion of the RCM sensor to the output of the ACM sensor. When the amount of salt deposit and humidity are actually varied and the ratio of corrosion of the RCM sensor to the output of the ACM sensor is confirmed, a linear relationship is observed, as indicated by the ●, ○, and □ marks.

[0035] Thus, the relationship between the ACM sensor output and corrosion rate shown in Figure 5 can be experimentally confirmed to be linear, as the slope of the ACM sensor output changes with humidity.

[0036] (The principle for obtaining the corrosion rate of zinc as a metal) Figure 8 shows the relationship between the output of the ACM sensor and relative humidity, and Figure 9 shows the principle of the ACM sensor. In Figure 8, the number in Fe() represents the amount of attached salt. The ACM sensor has an anode made of iron (Fe) and a cathode made of silver (Ag). The more salt that adheres and the higher the humidity, the greater the output of the ACM sensor tends to be. Since the amount of moisture absorbed by salt increases in proportion to the humidity, the amount of moisture absorbed × the amount of attached salt = the amount of water (water film thickness), and the thicker the water film, the greater the galvanic current.

[0037] In Figure 8, the amount of attached salt can be determined by measuring both humidity and the output of the iron (Fe) ACM sensor. For example, at the point marked with a star (humidity 90%, sensor output 0.01 μA), the amount of attached salt will be between 0.001 and 0.01, but it can be read by linear interpolation.

[0038] Methods for obtaining the corrosion rate of iron (Fe) include obtaining the amount of attached salt from the output of an ACM sensor and then determining the corrosion rate, and obtaining the daily average of the electric coulomb amount from the integrated output of the ACM sensor and then determining the corrosion rate.

[0039] The method of obtaining the amount of attached salt from the output of the ACM sensor and determining the corrosion rate is based on the database of sea salt attachment amount and metal corrosion rate shown in Figure 10, where many measured values ​​exist for attached salt amount and iron (Fe) corrosion rate, and the corrosion rate can be calculated from these empirical formulas.

[0040] The method of determining the corrosion rate by obtaining the daily average of the electric coulomb amount from the integrated output of the ACM sensor is based on the fact that the amount of attached salt does not actually increase or decrease rapidly. Therefore, the corrosion rate is calculated by formulating a mathematical equation using the daily average of the electric coulomb amount from the integrated output of the ACM sensor as shown in Figure 11.

[0041] In Figure 11, the horizontal axis represents logQ(C / day), and the vertical axis represents logCR(Fe), where logQ(C / day): Integrated output of Fe-ACM sensor (Coulombs) / per day logCR(Fe): Annual corrosion rate of Fe Therefore, the corrosion rate is calculated from the Fe-ACM sensor output integration (coulombs) per day: logCR(Fe)[mm / y] =0.379logQ[logQ(C / day)]-0.723 (See the paper "Environmental Corrosivity of Various Parts Inside Industrialized Housing," Tokyo University of Mercantile Marine, Graduate School of Engineering, University of Tokyo).

[0042] (Determine the corrosion rate of Zn from the corrosion rate of Fe) Figure 12 shows the relationship between the corrosion rates of iron (Fe) and zinc (Zn). In Figure 12, the horizontal axis represents the corrosion rate of zinc (Zn), and the vertical axis represents the corrosion rate of iron (Fe). The "+" marks indicate the case of a marine environment (exposure to seawater spray). Excluding these "+" marks, it can be considered that the corrosion rates of iron (Fe) and zinc (Zn) are proportional.

[0043] logCR(Zn): Annual corrosion rate of Zn logCR(Fe)[mm / y] =1.438+1.062logCR(Zn)[mm / y] Since the corrosion rate of iron (Fe) can be determined by Q, by combining the formulas, the corrosion rate of zinc (Zn) can be calculated from the Q obtained for Fe-ACM. Corrosion rate of Fe (from Q) logCR(Fe)[mm / y] =0.379logQ[logQ(C / day)]-0.723 Corrosion rate of Zn (from Q) logCR(Zn)[mm / y] =0.357logQ[logQ(C / day)]-2.035 In practical terms, by incorporating a safety factor, it can be considered useful as a rough prediction formula, even if the accuracy is somewhat poor (see the paper "Environmental Corrosivity of Various Parts Inside Industrialized Housing," Tokyo University of Mercantile Marine, Graduate School of Engineering, University of Tokyo).

[0044] (Reasons for using an ACM sensor with an iron (Fe) anode) While an ACM sensor with an iron (Fe) anode can calculate the corrosion rate of not only iron (Fe) but also zinc (Zn), an ACM sensor with an iron (Fe) anode has a short lifespan due to the corrosion of the iron (Fe) itself, which means that it needs to be replaced frequently in harsh corrosive environments.

[0045] Therefore, by using zinc (Zn), which has good corrosion resistance, as the anode of the ACM sensor, the lifespan of the ACM sensor can be extended. By determining the correlation between an ACM sensor with an iron (Fe) anode and an ACM sensor with a zinc (Zn) anode, it becomes possible to calculate the corrosion rate.

[0046] At the 66th Annual Scientific Conference of the Japan Society of Civil Engineers (FY2011), a study entitled "Evaluation of the Atmospheric Corrosion Environment of Steel Members Using an ACM-Type Corrosion Sensor with Zn / Ag Pairs" was presented.

[0047] The correlation between an ACM sensor with an iron (Fe) anode and an ACM sensor with a zinc (Zn) anode can be understood from the comparison diagram of sensor outputs in Figure 13(a).

[0048] Figure 13(a) shows data from actual exposure tests conducted in real environments on ACM sensors with an iron (Fe) anode and ACM sensors with a zinc (Zn) anode.

[0049] The vertical axis represents the output ratio of the Fe and Zn-ACM sensors (IFe / Izn), and the horizontal axis represents the output of the Zn-ACM sensor.

[0050] When the output of an ACM sensor with a zinc (Zn) anode exceeds 1 μA, the ratio remains constant at approximately 0.391, while below 1 μA, the ratio itself changes. This relationship can be expressed mathematically as shown in Figure 13(b).

[0051] The environmental monitoring in this embodiment uses an ACM sensor that obtains an output between the anode and cathode due to moisture, and measures the output of the ACM sensor to obtain the corrosive environmental properties of a metal structure.

[0052] In other words, as shown in Figure 14, the corrosion rate of zinc (Zn) can be determined from the coulombs / day of an ACM sensor with an iron (Fe) anode.

[0053] Next, in order to use an ACM sensor with a zinc (Zn) anode, which has a longer lifespan than an ACM sensor with an iron (Fe) anode, we will formulate a mathematical equation for the relationship between an ACM sensor with an iron (Fe) anode and an ACM sensor with a zinc (Zn) anode.

[0054] To determine the corrosion rate of zinc (Zn) from the output of an ACM sensor with a zinc (Zn) anode, 1) I Zn ⇒I Fe Convert 2) Converted I Fe The daily average Q of Coulombs is calculated by accumulating these values. The corrosion rate of zinc (Zn) is calculated using the formula.

[0055] In Figure 15(a), we verify the likelihood of the above combination.

[0056] Corrosion conditions: 1g / m 2 Apply sea salt and maintain a humidity of 90 / 60. The ACM sensor is an ACM sensor in which the anode is made of zinc (Zn), and the output of the ACM sensor is shown on the left vertical axis.

[0057] In Figure 15(b), the RCM sensor measures the corrosion thinning of zinc (Zn) by the change in resistance, with the corrosion depth (μm) on the right vertical axis.

[0058] The corrosion rate of zinc (Zn) is determined from the output of an ACM sensor with a zinc (Zn) anode using the conversion and formula described above.

[0059] This shows the relationship between the results of an ACM sensor with a zinc (Zn) anode [corrosion rate of zinc (Zn) converted to iron (Fe)] and the [amount of zinc (Zn) corrosion] of a zinc (Zn)-RCM sensor.

[0060] In Figure 15(c), Horizontal axis: Humidity Vertical axis: Ratio = Amount of zinc (Zn) corrosion (measured by RCM) ÷ Amount of zinc (Zn) corrosion (converted to ACM) data: ●, ○, □: These represent combinations of the amount of attached salt and the conditions under which a constant humidity was maintained.

[0061] If the method described so far for determining the corrosion rate of zinc (Zn) from an ACM sensor with a zinc (Zn) anode is correct, the ratio should be constant (ideally 1).

[0062] However, as humidity increases, the corrosion amount converted using ACM becomes smaller than the actual corrosion amount (RCM).

[0063] It's not simply a matter of misalignment; the ratio depends on humidity. In other words, the correlation in the real environment suggests that the coefficient (0.391) in the following equation is low.

[0064] The formula itself is derived by averaging in a real environment where humidity and salt deposits are constantly changing, so there is inherent room for improvement in accuracy, and one possible method for doing so is to correct for humidity.

[0065] A good method for correcting for humidity is to multiply by humidity, as shown in Figure 5, while considering the correlation equation and coefficients between ACM sensors with a zinc (Zn) anode and ACM sensors with an iron (Fe) anode, which have already been published in academic papers.

[0066] The output data from the ACM sensor is corrected with humidity data to obtain the corrosion rate of a metal, which is zinc (Zn), and the ratio changes depending on the humidity. Zinc (Zn) has the property of becoming more protective and less susceptible to corrosion due to the formation of a corrosion product called basic zinc chloride. This protective film is more easily formed at higher salt concentrations, so when humidity is high, the amount of moisture absorbed increases and the salt concentration decreases, making it difficult for the protective film to form and thus allowing corrosion to progress more easily. Even if the amount of attached salt is changed, this ratio depends on the humidity, so it is thought that the corrosion of zinc (Zn) is strongly dependent on the salt concentration. In addition to zinc (Zn), copper is another metal that naturally produces basic metal chloride, so copper is the other metal besides zinc (Zn) that is targeted. [Industrial applicability]

[0067] This invention can be applied to environmental monitoring methods and devices for monitoring atmospheric corrosion of structures exposed to the atmospheric environment, and it is possible to obtain the corrosion rates of various metals with a simple configuration. [Explanation of Symbols]

[0068] 1 ACM sensor 2 Anodes 3 Cathode 4. Insulating layer 10. Environmental monitoring device 12 Measuring meter 13 Temperature and Humidity Sensor 14 Data Loggers 14a Correction section 14b Processing Unit

Claims

1. This is an environmental monitoring method for obtaining the corrosive environmental properties of a metal structure by using a sensor that obtains the output between the anode and cathode, and measuring the output of the sensor. In an environmental monitoring method for obtaining the corrosion rate of a metal using the output data of the aforementioned sensor and humidity data, The previous sensor is an ACM sensor. The anode of the ACM sensor is made of zinc or a zinc alloy. When correcting the output data of the ACM sensor with humidity data to obtain the zinc corrosion rate, An environmental monitoring method characterized by obtaining a linear relationship that defines the output of the ACM sensor and the corrosion rate of the zinc, wherein the linear relationship is configured such that the gradient increases as the humidity increases, and obtaining the corrosion rate of the zinc corresponding to the output of the ACM sensor in the linear relationship.

2. The environmental monitoring method according to Claim 1, characterized in that the ACM sensor has a cathode made of silver or carbon.

3. An environmental monitoring device that obtains the corrosive environmental properties of a metal structure by using a sensor that obtains the output between the anode and the cathode, and measuring the output of the sensor, A temperature and humidity sensor that obtains humidity data, A data unit that obtains the output data from the aforementioned sensor and the humidity data from the temperature and humidity sensor, A processing unit that obtains the corrosion rate of a metal using output data and humidity data, In an environmental monitoring device including, The previous sensor is an ACM sensor. The anode of the ACM sensor is made of zinc or a zinc alloy. The data unit obtains the output data from the sensor and the humidity data from the temperature and humidity sensor, When the processing unit obtains the zinc corrosion rate using the output data and humidity data, An environmental monitoring device characterized by obtaining a linear relationship that defines the output of the ACM sensor and the corrosion rate of the zinc, wherein the linear relationship is configured such that the gradient increases as the humidity increases, and obtaining the corrosion rate of the zinc corresponding to the output of the ACM sensor in the linear relationship.

4. The environmental monitoring device according to Claim 3, characterized in that the ACM sensor has a cathode made of silver or carbon.

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