JP2008261652A - Sensor for measuring amount of corrosion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor for measuring the amount of corrosion and capable of accurately measuring the amount of corrosion in the same corrosive environment as that of a structure for a long period. <P>SOLUTION: The sensor 1 for measuring the amount of corrosion has both an exposed material 10 to be exposed to a corrosive environment and a supporting material 11 for supporting the exposed material 10 in its elastically bent state. The elastic bending of the exposed material 10 is maintained at a prescribed curvature. A distortion gauge 15 for detecting bending distortion is pasted to the surface of the exposed material 10. It is possible to accurately measure the temporal transition of the amount of corrosion in the same corrosive environment as that of a structure for a long period through the use of a few number of the sensors for measuring the amount of corrosion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for evaluating durability against corrosion deterioration of a structure, and more particularly to a corrosion amount measurement sensor for continuously measuring the corrosion amount of a structure.

Until now, techniques for predicting various amounts of corrosion have been considered. For example, Non-Patent Document 1 includes a gravimetric method (Corrosion Coupons and
Details of Weight Loss Analysis are described. In this method, a test piece made of the same steel material as that of the structure to be evaluated for corrosion is placed on a stand and exposed to the required time for corrosion, and then recovered. Thereafter, the surface rust is removed and the weight is measured, and the weight loss due to corrosion wear is measured.

In many exposure tests, it is necessary to conduct a corrosion test that captures changes over time, and many test pieces are required. Further, considering the variation in the corrosion test results, generally three or more test pieces are required under the same conditions, which is also a factor that requires a large number of test specimens. Generally, the test piece per piece is 300 g, and usually about 50 pieces are exposed. Therefore, the total weight of the test piece is 15 kg and a space of about 2 m ² is required, and the frame and other equipment required for this purpose are considerably large. In addition, a lot of labor is required for installing, collecting, and investigating test pieces.

  Non-Patent Document 2 describes a corrosion rate measurement technique using an electric resistance measurement method (Electric Resistance Method) and a linear polarization resistance method (LPR method) which is one of electrochemical measurement methods.

The principle of the electrical resistance measurement method utilizes the feature that the cross section of the test piece is reduced due to corrosion and the metal resistance increases accordingly. However, the general resistance of the metal test piece is very small at a specific resistance of 9.7 × 10 ⁻⁶ Ωcm. For this reason, it is difficult to electrically detect the resistance change. Therefore, it is necessary to minimize the cross-sectional area of the test piece and increase the total resistance of the test piece. Therefore, it is necessary to process the rod to have a length of about 50 mm and a diameter of about 1.0 mm or less, and for the plate to have an area of 1 cm × 1 cm and a thickness of about 0.2 mm or less. Therefore, when it is desired to use a very thick round bar or a test piece having a large test area, the corrosion test becomes difficult.

The linear polarization resistance method is a method of measuring a polarization resistance measured based on an electrochemical theory, that is, a corrosion reaction resistance, and converting this to a corrosion rate. In this method, even if an instantaneous corrosion rate is obtained, it is not possible to obtain a corrosion amount accumulated for a long period. Moreover, even if the instantaneous corrosion rate is integrated, the comparison with the actual corrosion weight may not always match. The electrochemical measurement method uses electrochemical theory that polarization resistance and corrosion rate are inversely proportional, and continuously measures polarization resistance and predicts the amount of corrosion from the integrated value. It is necessary to obtain a conversion coefficient for each condition in advance, and an experiment for that is necessary separately, which requires a lot of time and effort.
Corrosion Coupons and Weight Loss Analysis <URL: http://www.alspi.com/cpnintro.htm> Plant Engineer, pp31-33, Vol.31, December issue, 1999

  Conventionally, measurement of the amount of corrosion by the gravimetric method has been common, but there are variations from specimen to specimen, and a large number of specimens are required to grasp the time transition of corrosion, and the cost is high. It was. An object of the present invention is to obtain a corrosion amount measurement sensor capable of measuring a corrosion amount with high accuracy over a long period of time in the same corrosive environment as that of a structure.

  In order to achieve this object, according to the present invention, an exposed material exposed to a corrosive atmosphere, and a support material that supports the exposed material in a state in which the exposed material is elastically bent, There is provided a corrosion amount measuring sensor characterized in that the elastic bending of the exposed material is maintained at a constant curvature, and a strain gauge for detecting bending strain is attached to the surface of the exposed material.

  In this corrosion amount measurement sensor, the support material may be substantially rigid. Moreover, the said support material may have a press member which produces the elastic bending by pressing the surface of the said exposed material. The support material may be covered so as not to be exposed to a corrosive atmosphere. Further, the support material and the exposed material may be plate-shaped, and a ratio of the plate thickness of the exposed material to the plate thickness of the support material may be 0.5 or less.

  Further, in this corrosion amount measurement sensor, the support material is an elastic body, and the elastic bending of the exposed material is constant by changing the force acting between the exposed material and the support member. The curvature may be maintained. In this case, the support material may be capable of being exposed to a corrosive atmosphere. Here, the elastic body includes a completely elastic body and an elastic-plastic body.

  Further, according to the present invention, the exposed material exposed to a corrosive atmosphere, and a support material that supports the exposed material in a state in which the exposed material is elastically bent, the at least one of the exposed material and the support material, A corrosion amount measuring sensor is provided, in which a strain gauge for detecting strain generated by a force acting between an exposed material and the support material is attached.

  In this corrosion amount measurement sensor, the support material may be an elastic body. The support material may not be exposed to a corrosive atmosphere.

  The corrosion amount measurement sensor of the present invention may further have a temperature correction gauge.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to measure the time transition of corrosion amount accurately over a long period of time using the small number of corrosion amount measurement sensors in the same corrosive environment as a structure.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view of a corrosion amount measuring sensor 1 according to a first embodiment of the present invention. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  The corrosion amount measuring sensor 1 has a flat exposed material 10 and a support material 11, and the exposed material 10 and the support material 11 are overlapped so that both end portions of the exposed material 10 are placed on both end portions of the support material 11. The configuration is pasted. Both the exposed material 10 and the support material 11 are rectangular, for example.

  The exposed material 10 is an elastic material. For example, when inspecting the corrosion deterioration of the structure, the exposed material 10 is made of the same material as the structural member of the structure to be inspected for corrosion. The exposed material 10 is made of a metal material such as steel. On the other hand, the support material 11 has sufficiently larger rigidity than the exposed material 10, and the exposed material 10 is an elastic body, whereas the support material 11 can be regarded as a substantially rigid body. Although the exposed material 10 is also made of a metal material such as steel, for example, the support material 11 is considered to be substantially rigid with respect to the exposed material 10, and thus the support material 11 has a bending rigidity larger than that of the exposed material 10. I.e. having a greater modulus or greater thickness. For example, when the support material 11 and the exposed material 10 are the same material and have the same elastic modulus, if the ratio of the plate thickness of the exposed material 10 to the plate thickness of the support material 11 is 0.5 or less, The support material 11 can be regarded as a substantially rigid body.

  As shown in the drawing, both ends of the exposed material 10 are attached to both ends of the support material 11 in a state where the center of the exposed material 10 is curved and the exposed material 10 is elastically bent. Thereby, a sealed space 12 is formed in the corrosion amount measuring sensor 1. Here, the sealed space may be in a completely sealed state, but it is desirable that there be a minute gap or opening that makes the atmospheric pressure equal to the internal pressure.

  A strain gauge 15 is attached to the inner surface of the exposed material 10 in the sealed space 12. As described above, due to the occurrence of elastic bending in the exposed material 10, bending strain that becomes tensile occurs on the outer surface of the exposed material 10, and bending strain that compresses occurs on the inner surface of the exposed material 10. is doing. The strain gauge 15 detects a bending strain that is compressed on the inner surface of the exposed material 10.

  The detection signal of the strain gauge 15 is input to the bridge circuit 17 disposed outside by the lead wire 16. In the bridge circuit 17, a compressive bending strain generated on the inner surface of the exposed material 10 is detected based on a change in the resistance value detected by the strain gauge 15. In FIG. 1, the lead wire 16 leading portion of the exposed material 10 is opened. Here, the bridge circuit 17 includes not only a bridge circuit that converts a strain gauge resistance change into a voltage change, but also an amplifier function that amplifies the voltage change, a function that digitizes and displays the voltage, and a function that outputs the voltage externally. Is included.

  The outer surface of the support material 11 is covered with a cover 20 for preventing corrosion. As a result, the support material 11 is not exposed to the corrosive atmosphere. On the other hand, the outer surface of the exposed material 10 is exposed. For this reason, the outer surface of the exposed material 10 is in a state exposed to a corrosive atmosphere.

  For example, when the corrosion deterioration of a structure is inspected, the corrosion amount measuring sensor 1 configured as described above is installed in the same environment as the structural member to be inspected for corrosion. As a result, the exposed material 10 is exposed to the same corrosive atmosphere as the component to be inspected, and the plate thickness of the exposed material 10 gradually decreases with the progress of corrosion.

  The bridge circuit 17 detects a compressive bending strain generated on the inner surface of the exposed material 10 based on a change in the resistance value detected by the strain gauge 15. As the corrosion progresses, the compressive bending strain generated on the inner surface of the exposed material 10 gradually decreases. By detecting this bending strain, the plate thickness of the exposed material 10 is obtained, and the amount of corrosion is determined. Can be measured.

  Here, FIGS. 2 and 3 are explanatory views showing changes in compression bending strain generated on the inner surface of the exposed material 10 as corrosion progresses. FIG. 2 shows a state where the exposed material 10 is still thick, and FIG. 3 shows a state where the exposed material 10 is thin. As described above, the exposed material 10 is supported at both ends by the support material 11 in a state having an elastic bending. For this reason, even if the plate | board thickness of the exposed material 10 becomes thin by progress of corrosion, the elastic bending of the exposed material 10 is always maintained at a fixed curvature. Therefore, in FIGS. 2 and 3, the neutral axis 10 'of the exposed material 10 has an equal curvature.

  As shown in FIGS. 2 and 3, in the exposed material 10, a bending stress σ that is pulled parallel to the neutral shaft 10 ′ acts above the neutral shaft 10 ′, and below the neutral shaft 10 ′, the neutral shaft 10 ′ A bending stress σ is applied in parallel with the vertical axis 10 ′. Since the bending stress σ is proportional to the height from the neutral axis 10 ′, the compressive bending strain ε generated on the inner surface of the exposed material 10 is also proportional to the height H from the neutral axis 10 ′.

  Therefore, when the corrosion has not yet progressed and the exposed material 10 is still thick as shown in FIG. 2, the height H from the neutral shaft 10 ′ (the distance from the neutral shaft 10 ′ to the inner surface of the exposed material 10). That is, half of the exposed material 10) is relatively large. Therefore, the compressive bending strain ε generated on the inner surface of the exposed material 10 also becomes relatively large.

  On the other hand, when the corrosion progresses and the plate thickness of the exposed material 10 is reduced as shown in FIG. 3, the height H from the neutral shaft 10 'is also relatively reduced. Therefore, the compressive bending strain ε generated on the inner surface of the exposed material 10 is also relatively small.

  Thus, the compressive bending strain ε produced on the inner surface of the exposed material 10 is proportional to the plate thickness of the exposed material 10. For this reason, in the bridge circuit 17, if the plate | board thickness of the exposed material 10 is calculated | required based on the change of the bending-strain (epsilon) resistance value detected by the strain gauge 15, the corrosion amount of the exposed material 10 can be measured easily. Since the exposed material 10 is exposed to the same corrosive atmosphere as the component to be inspected, the amount of corrosion of the component to be inspected can be measured by the amount of corrosion of the exposed material 10. Therefore, by using the corrosion amount measuring sensor 1 according to the first embodiment of the present invention, it is possible to accurately measure the time transition of the corrosion amount over a long period of time in the same corrosive environment as the structure. Become.

  4 to 9 are modified examples of the corrosion amount measuring sensor 1 according to the first embodiment of the present invention. The corrosion amount measurement sensor 1 shown in FIG. 4 further has a temperature correction gauge 21. In the corrosion amount measurement sensor 1 shown in FIG. 4, a temperature correction gauge 21 is built in the sealed space 12.

  Since the corrosion amount measuring sensor 1 is installed in the same corrosive environment as the structure, it is affected by the temperature change of the outside air and the exposed material 10 and the support material 11 constituting the corrosion amount measuring sensor 1 are thereby expanded. The material is shrunk and heat distortion occurs on the inner surface of the exposed material 10. A plate 21 'for temperature correction is prepared inside, a temperature correction gauge 21 is attached to the plate 21', and this is used to cancel the influence of such thermal strain, thereby changing the temperature of the outside air, etc. It is possible to accurately measure the amount of corrosion without being affected by.

  Note that the temperature correction gauge 21 that cancels the influence of thermal strain in this way is not necessarily built in the corrosion amount measurement sensor 1. For example, in FIG. 5, a plate piece 21 'for temperature correction is prepared in the same corrosive environment as the structure separately from the corrosion amount measuring sensor 1, and a temperature correction gauge 21 is attached to the plate piece 21'. Even with such a configuration, it is possible to accurately measure the amount of corrosion by canceling the influence of thermal distortion and without being affected by the temperature change of the outside air.

  The corrosion amount measurement sensor 1 shown in FIG. 6 has a pressing member 22 that presses the inner surface of the exposed material 10 to cause elastic bending. FIG. 7 is a plan view of the corrosion amount measuring sensor 1 shown in FIG.

  In this example, the pressing member 22 is a screw, and by attaching the pressing member 22 from the lower surface of the support material 11, the tip of the pressing member 22 pushes the inner surface of the exposed material 10 outward in the sealed space 12. Thus, the support material 11 is forced to bend elastically.

  In this manner, the amount of corrosion can be accurately measured in the same manner by causing the support member 11 to bend elastically using an appropriate pressing member 22 and detecting the change in bending strain with the strain gauge 15.

  In the corrosion amount measurement sensor 1 shown in FIG. 8, the support material 11 is also an elastic body, and the exposed material 10 is elastically bent by the force acting between the exposure material 10 and the support member 11. In the corrosion amount measuring sensor 1 shown in FIG. 8, a bending moment M acts on the exposed material 10 from the support material 11 at both ends of the exposed material 10. Naturally, the bending moment M having the same magnitude acts on the support material 11 from the exposed material 10 in the opposite direction also at both ends of the support material 11. Due to the reverse bending moment M received from the exposed material 10, the support material 11 is also elastically bent.

  As described above, the bending moment M acts between the exposed material 10 and the support member 11, so that both the exposed material 10 and the support member 11 are elastically bent. A gap having a distance of 2δ is generated between the inner surface center portion of the support member 11 and the inner surface center portion of the support member 11. In this example, the exposed material 10 and the support member 11 are made of plates having the same plate thickness and the same elastic modulus. For this reason, the elastic bending which has arisen in the exposed material 10 and the supporting member 11 is a target shape.

  In the corrosion amount measurement sensor 1 of FIG. 8, the outer surface of the support material 11 is not covered with the cover 20, and similarly to the exposed material 10, the outer surface of the support material 11 is also exposed to the corrosive atmosphere. .

  According to the corrosion amount measuring sensor 1 of FIG. 8, the exposed material 10 and the support material 11 are similarly corroded by being exposed to a corrosive atmosphere. Along with this corrosion, the bending moment M acting between the exposed material 10 and the support member 11 also decreases. However, as the thickness of the exposed material 10 and the support material 11 decreases as the corrosion progresses. Bending rigidity also decreases. By canceling the decrease in the bending moment M and the decrease in the bending rigidity, the elastic bending of the exposed material 10 can be maintained at a constant curvature. Thus, the amount of corrosion can be similarly measured from the plate thickness of the exposed material 10 detected by the strain gauge 15.

  A corrosion amount measurement sensor 1 shown in FIG. 9 is a modification of the corrosion amount measurement sensor 1 of FIG. 8, and a flat intermediate member 25 is disposed between the exposed material 10 and the support member 11. 9, the exposed material 10 and the support material 11 are similarly corroded, thereby reducing the bending moment M acting between the exposed material 10 and the support member 11, and the exposure. The decrease in bending stiffness between the material 10 and the support material 11 is offset, and the elastic bending of the exposed material 10 can be maintained at a constant curvature. Thus, the amount of corrosion can be similarly measured from the plate thickness of the exposed material 10 detected by the strain gauge 15.

  FIG. 10 is a graph calculated by the strain calculation formula (1) when the plate thickness t of the exposed material 10 and the support member 11 decreases in the corrosion amount measurement sensor 1 of FIGS. The calculation condition was changed from t = 0.184 to 0.0 under the condition that the length L of the exposed material 10 and the support material 11 was L = 50 mm and the plate interval δ = 1.41 mm.

  Next, FIG. 11 is a schematic explanatory view of a corrosion amount measuring sensor 2 according to the second embodiment of the present invention. FIG. 12 is a schematic explanatory diagram of the corrosion amount measurement sensor 2 in a state where corrosion has progressed.

  In this corrosion amount measurement sensor 2, both the exposed material 10 and the support material 11 are elastic bodies, and acts between the exposed material 10 and the support member 11, as in the corrosion amount measurement sensor 1 described above with reference to FIG. 8. The exposed material 10 is elastically bent by the force to be applied. A bending moment M acts on the exposed material 10 from the support material 11 at both ends of the exposed material 10. Also, the bending moment M having the same size acts in the opposite direction from the exposed material 10 to the support material 11 at both ends of the support material 11.

  In a sealed space 12 formed inside the corrosion amount measuring sensor 2, a strain gauge 30 is attached to the inner surface of the support material 11 in addition to the strain gauge 15 on the inner surface of the exposed material 10. The outer surface of the support material 11 is covered with a cover 20 for preventing corrosion. As a result, the support material 11 is not exposed to the corrosive atmosphere. On the other hand, the outer surface of the exposed material 10 is exposed. For this reason, the outer surface of the exposed material 10 is in a state exposed to a corrosive atmosphere.

  In this corrosion amount measuring sensor 2, the length of the exposed material 10 and the support material 11 is L, the distance between the inner surface of the exposed material 10 and the inner surface of the support material 11 is ΔL, the plate thickness of the exposed material 10 is t 1, the plate of the support material 11. If the thickness is t2, the bending strain of the exposed material 10 inner surface is ε1, and the bending strain of the inner surface of the support material 11 is ε2, then the bending strain ε1 of the exposed material 10 inner surface and the bending strain ε2 of the inner surface of the supporting material 11 are respectively Approximate calculation can be performed using equations (2) and (3).

  FIG. 13 illustrates the coefficients α and β in the equations (2) and (3) calculated in the range where the plate thickness ratio t1 / t2 is 0.0 to 1.0. In the figure, ◆ represents a curve of coefficient α, and ■ represents a curve of coefficient β. The coefficient α is a value of t1 in the range where the thickness ratio t1 / t2 is 0.5 or less, that is, in the range where the thickness t1 of the exposed material 10 is corroded to become less than half the thickness t2 of the support material 11. The change is almost linear. That is, when the thickness ratio t1 / t2 is 0.5 or less, the support material 11 can be regarded as a substantially rigid body with respect to the exposed material 10, and the elastic bending of the exposed material 10 is maintained at a substantially constant curvature. Is done. Therefore, the resistance value (bending strain ε1 on the inner surface of the exposed material 10) detected by the strain gauge 15 becomes substantially proportional to the plate thickness ratio t1 / t2.

  On the other hand, the coefficient β is equal to or less than t1 in the range where the plate thickness ratio is 1.0 or less and 0.5 or more, that is, the range until the plate thickness t1 of the exposed material 10 becomes half the plate thickness t2 of the support material 11. The change is almost linear. That is, in the range where the thickness ratio t1 / t2 exceeds 0.5, the bending moment M acting on the support material 11 from the exposed material 10 becomes smaller as the thickness t1 of the exposed material 10 decreases. In proportion to this, the curvature of the elastic bending generated in the support material 11 also decreases, and the bending strain ε2 on the inner surface of the support material 11 decreases. Therefore, the resistance value (bending strain ε2 of the inner surface of the support material 11) detected by the strain gauge 30 becomes substantially proportional to the plate thickness ratio t1 / t2.

  In particular, in the initial range in which the plate thickness ratio decreases from 1.0, the elastic bending curvature of the exposed material 10 increases conversely due to the influence of the decrease in the elastic bending curvature occurring in the support material 11. To do. For this reason, in the initial range where the plate thickness ratio decreases from 1.0, the bending strain ε2 of the inner surface of the support member 11 tends to increase slightly.

  FIG. 14 is a graph in which the initial value of the thickness of the exposed material 10 is t1 = 0.184 mm, the thickness of the support material 11 is t2 = 0.75 mm, and the initial thickness is the thickness ratio t1 / t2 = 0.24. . Length: L = 50 mm and plate spacing ΔL = 2.82 mm. The example calculated using Formula (2) about the case where the plate | board thickness of the exposed material 10 is reduced from initial plate | board thickness to 0 is shown. The horizontal axis is the remaining thickness t1, and the vertical axis is the strain ε1 of the exposed material 10.

  FIG. 15 is a graph calculated using Equation (2) under the same conditions as described above. The horizontal axis is the remaining thickness t1, and the vertical axis is the strain ε2 of the support material 11.

  As shown in FIGS. 13 to 15, in the corrosion amount measurement sensor 2 according to the second embodiment of the present invention, the exposed material 10 is within the range where the thickness ratio t1 / t2 is 0.5 or less. The bending strain ε1 of the inner surface is substantially proportional to the plate thickness ratio t1 / t2, and in the range where the plate thickness ratio t1 / t2 exceeds 0.5, the bending strain ε2 of the inner surface of the support material 11 is substantially proportional to the plate thickness ratio t1 / t2. To come. Therefore, when the plate thickness ratio t1 / t2 is 0.5 or less, the amount of corrosion is measured based on the resistance value detected by the strain gauge 15, and when the plate thickness ratio t1 / t2 exceeds 0.5. It is also conceivable to measure the amount of corrosion based on the resistance value detected by the strain gauge 30.

  The coefficients α and β are not proportional to the corrosion amount over the entire range where the plate thickness ratio t1 / t2 is 0 to 1.0. However, as shown in FIG. 13, it is known that the coefficients α and β have a certain relationship with the plate thickness ratio t1 / t2. Therefore, in the corrosion amount measuring sensor 2, as shown in FIG. 11, it is not always necessary to attach strain gauges to both the exposed material 10 inner surface and the support material 11 inner surface. A strain gauge may be attached to either one.

  In the above, since the exposed material 10 and the support material 11 are simple in shape, the description has been made using the strain calculation formula based on several assumptions. However, it is difficult to derive the calculation formula when the exposed material or support material has a more complicated shape. In such a case, structural analysis by the finite element method or the like can be performed, and the strain generated in the exposed material or the support material can be calculated. As another method, it is also effective to manufacture a real-shaped corrosion amount measurement sensor and measure the strain generated in the exposed material and the support material through experiments.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to. For example, as the exposed material and the support material, resin, rubber and the like can be used in addition to metal materials such as steel, stainless steel, copper, aluminum, titanium, and other alloys. Further, the strain gauge for detecting the bending strain does not necessarily have to be attached to the inner surface of the exposed material and the support material, and can be attached to the outer surface. In addition, when sticking the both ends of the exposure material 10 to the both ends of the support material 11, an adhesive agent, welding, etc. can be utilized.

The corrosion amount measurement sensor described in FIG. 1 was manufactured under the following conditions.
Exposed material: Carbon steel SS400, thickness t1 = 0.184mm,
Support material: Carbon steel SS400 Thickness t2 = 0.75mm
Dimensions of steel plate used for exposed material and support material: L = 50mm, width B = 30mm
Strain gauge: Kyowa Dengyo Gauge length 5mm, with 2m lead wire (Product number: KFG-5-120-C1)
End bonding method: Metal adhesive, product name "Velometal cold welding system" manufactured by Verometal Japan Co., Ltd.
Plate interval ΔL = 2.82 mm (The interval was maintained using a metal spacer.)

  In the measurement, temperature correction was performed. As a temperature correction gauge, the same gauge as above was attached to a steel plate having a thickness of 0.184 mm, and the entire front and back surfaces were covered with an acid-resistant insulating tape. In the strain measurement, a circuit that performs temperature correction by the bridge method was configured to perform continuous measurement. The measurement interval is 0.5 seconds.

  About 500 ml of a 5.0% nitric acid solution was placed in a beaker, and a corrosion amount measurement sensor was immersed in the beaker to measure strain. At the same time, for the purpose of measuring the corrosion plate thickness, four corrosion test pieces having a steel plate thickness of 0.368 mm were prepared and simultaneously immersed in the same corrosion solution. After the start, 200 seconds, 400 seconds and 500 seconds later, one corrosion test piece was taken out, and the plate thickness was measured with a point micrometer.

  FIG. 16 is a graph showing a temporal change in the strain measurement value measured by the corrosion amount measurement sensor. 17 and 18 show the corrosion amount measurement sensor after the corrosion test. Further, the relationship between the remaining thickness and the time was as shown in FIG. 19 by the corrosion test piece pulled up at each time. The result of FIG. 16 and the result of FIG. 19 are compared with each other as shown in Table 1. The remaining plate thickness (estimated plate thickness and estimated value) estimated from the strain measurement value by the corrosion amount measurement sensor and the remaining plate thickness (test piece value) measured from the corrosion test piece agreed well.

  The present invention can be applied to the measurement of corrosion deterioration of structures and the like.

It is a schematic explanatory drawing of the corrosion amount measurement sensor concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the change of the bending strain of the compression which has arisen in the inner surface of the exposed material with progress of corrosion, and has shown the state where the plate | board thickness of an exposed material is still thick. It is explanatory drawing which shows the change of the bending strain of the compression which has arisen on the inner surface of the exposed material with progress of corrosion, and has shown the state where the plate | board thickness of the exposed material became thin. It is a modification of the corrosion amount measuring sensor according to the first embodiment of the present invention, and has a temperature correction gauge. It is a modification of the corrosion amount measurement sensor according to the first embodiment of the present invention, and has a temperature correction gauge separately from the corrosion amount measurement sensor. It is a modification of the corrosion amount measuring sensor according to the first embodiment of the present invention, and has a pressing member that presses the inner surface of the exposed material to cause elastic bending. FIG. 7 is a plan view of the corrosion amount measurement sensor shown in FIG. 6. It is a modification of the corrosion amount measuring sensor according to the first embodiment of the present invention, and the exposed material is elastically bent by the force acting between the exposed material and the support member. It is a modification of the corrosion amount measurement sensor of FIG. 8, and a flat intermediate material is disposed between the exposed material and the support member. 10 is a graph calculated by the strain calculation formula (1) when the plate thickness t of the exposed material and the support member is decreased in the corrosion amount measurement sensor of FIGS. It is a schematic explanatory drawing of the corrosion amount measuring sensor concerning the 2nd Embodiment of this invention. FIG. 12 is a schematic explanatory view of a corrosion amount measurement sensor according to the second embodiment of the present invention in a state where corrosion has progressed. In the corrosion amount measurement sensor according to the second embodiment of the present invention, the coefficient α and the coefficient β are calculated in the range where the plate thickness ratio t1 / t2 is 0.0 to 1.0, and are shown in the graph. . It is a graph which shows the relationship between the residual plate | board thickness of an exposed material, and bending distortion (epsilon) 1. It is a graph which shows the relationship between the residual plate | board thickness of an exposed material, and bending distortion (epsilon) 2. It is a graph which shows the time change of the strain measurement value measured by the corrosion amount measurement sensor of an Example. It is a photograph which shows the corrosion amount measurement sensor after a corrosion test. It is a photograph which shows the corrosion amount measurement sensor after a corrosion test. It is a graph which shows the relationship between the remaining board | plate thickness measured with the corrosion test piece, and corrosion time.

Explanation of symbols

1, 2 Corrosion amount measurement sensor 10 Exposed material 11 Support material 12 Sealed space 15 Strain gauge 16 Lead wire 17 Bridge circuit 20 Cover 21 Temperature correction gauge 21 'Plate piece 22 Press member 25 Intermediate material 30 Strain gauge

Claims (11)

  An exposed material exposed to a corrosive atmosphere, and a support material that supports the exposed material in a state in which the exposed material is elastically bent, the elastic bending of the exposed material is maintained at a constant curvature, A corrosion amount measuring sensor, wherein a strain gauge for detecting bending strain is attached to the surface of an exposed material.   The corrosion amount measurement sensor according to claim 1, wherein the support member is substantially rigid.   The corrosion amount measurement sensor according to claim 1, wherein the support member includes a pressing member that presses a surface of the exposed material to cause elastic bending.   The corrosion amount measurement sensor according to claim 1, wherein the support material is covered so as not to be exposed to a corrosive atmosphere.   The support material and the exposed material are plate-shaped, and the ratio of the thickness of the exposed material to the thickness of the support material is 0.5 or less. Corrosion amount measuring sensor as described.   The support material is an elastic body, and an elastic bending of the exposed material is maintained at a constant curvature by changing a force acting between the exposed material and the support member. Item 5. The corrosion amount measurement sensor according to item 1.   The corrosion amount measurement sensor according to claim 6, wherein the support material can be exposed to a corrosive atmosphere.   An exposed material that is exposed to a corrosive atmosphere; and a support material that supports the exposed material in a state in which the exposed material is elastically bent. At least one of the exposed material and the support material includes the exposed material and the support material. A corrosion amount measuring sensor, wherein a strain gauge for detecting a strain generated by a force acting between the two is attached.   The corrosion amount measurement sensor according to claim 8, wherein the support material is an elastic body.   10. The corrosion amount measurement sensor according to claim 8, wherein the support material is not exposed to a corrosive atmosphere.   Furthermore, it has a temperature correction gauge, The corrosion amount measurement sensor in any one of Claims 1-10 characterized by the above-mentioned.

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