JP5912516B2 - Humidity evaluation method - Google Patents

Description

  The present invention relates to a corrosion evaluation method and a humidity evaluation method.

  The ACM sensor is a self-corrosion sensor and has a configuration for measuring a corrosion current flowing in a water film on a metal surface. Then, the corrosiveness of the environment is quantitatively evaluated by analyzing the output current amount of the ACM sensor.

JP 2008-157647 A

  An object of the present invention is to provide a corrosion evaluation method and a humidity evaluation method capable of performing more accurate corrosion evaluation and humidity evaluation.

  The corrosion evaluation method of the present invention that solves the above problem is a corrosion evaluation method for evaluating the corrosiveness of the environment, and correlates the temperature, the humidity, the amount of sea salt particles, and the amount of corrosion current of the ACM sensor. The step of determining in advance, the step of measuring the temperature, humidity and the amount of sea salt particles in the environment, and the amount of corrosion current in the environment based on the measured temperature, humidity and the amount of sea salt particles. And a step of calculating.

  According to the present invention, since the temperature of the environment in addition to the humidity of the environment and the amount of sea salt particles is a requirement, the correlation with the amount of corrosion current is obtained. Can be evaluated accurately. For example, in a mild environment such as indoors that is not directly exposed to wind and rain, the amount of corrosion current is small, and when measured using an ACM sensor, the output value may be small and accuracy may be reduced. By making the temperature a requirement in addition to the amount of sea salt particles, an accurate corrosion current amount can be calculated even in a mild environment.

  The humidity evaluation method of the present invention that solves the above-mentioned problem is a humidity evaluation method for evaluating the humidity of the environment, and the correlation between the temperature, the humidity, the amount of sea salt particles, and the amount of corrosion current of the ACM sensor is previously determined. Obtaining the step, adjusting the environment to a preset amount of sea salt particles, measuring the temperature and the amount of corrosion current of the ACM sensor under the environment, the measured temperature, And calculating a humidity of the environment based on the amount of corrosion current of the ACM sensor and a preset amount of sea salt particles.

  According to the present invention, in addition to the humidity of the environment and the amount of sea salt particles, the temperature of the environment is also a requirement, and the correlation with the amount of corrosion current is obtained. Therefore, the humidity can be accurately calculated, and the humidity of the environment can be accurately calculated. Can be evaluated. For example, while a polymer film type hygrometer has a large error in a high humidity region, the accuracy of an ACM sensor used in the present invention does not change even in a high humidity region. In addition, the polymer film type hygrometer cannot be used in the condensation region, whereas the ACM sensor used in the present invention can be used in the condensation region. Therefore, the humidity evaluation method of the present invention can calculate humidity in a wider environment.

  The humidity evaluation method of the present invention preferably includes a step of removing the oxide film formed on the substrate surface of the ACM sensor by washing with an acid before the step of adjusting the amount of sea salt particles in the environment.

  According to the humidity evaluation method of the present invention, since the oxide film is removed by washing with an acid as a preparation for measurement, it is possible to prevent a decrease in sensitivity of the ACM sensor due to the oxide film. In addition, when a plurality of ACM sensors are used or when the same ACM sensor is repeatedly used, variations in sensitivity can be prevented.

  According to the present invention, since the temperature of the environment in addition to the humidity of the environment and the amount of sea salt particles is a requirement, the correlation with the amount of corrosion current is obtained. Can be evaluated accurately. For example, in a mild environment such as indoors that is not directly exposed to wind and rain, the amount of corrosion current is small, and when measured using an ACM sensor, the output value may be small and accuracy may be reduced. By making the temperature a requirement in addition to the amount of sea salt particles, an accurate corrosion current amount can be calculated even in a mild environment.

The figure explaining the structure of an ACM sensor. The graph which shows correlation with temperature, humidity, the amount of sea salt particles, and the amount of corrosion current of an ACM sensor. The graph which shows correlation with temperature, humidity, the amount of sea salt particles, and the amount of corrosion current of an ACM sensor. The graph which shows correlation with temperature, humidity, the amount of sea salt particles, and the amount of corrosion current of an ACM sensor. The figure explaining the Example of the humidity evaluation method. The graph explaining a prior art.

<First embodiment>
Next, a first embodiment will be described.
1A and 1B are diagrams illustrating the configuration of an ACM sensor, in which FIG. 1A is a plan view, and FIG. 1B is a diagram schematically showing an enlarged part of a section taken along line II-II in FIG.

  The ACM sensor 1 has a structure in which an insulating film 3 and a conductive film 4 are laminated on the surface of a substrate 2 made of a target metal. In the present embodiment, the substrate 2 is made of Zn, and the conductive film 3 is made of Ag. Conductive wires are drawn out and connected to a measuring instrument (ACM logger) (not shown).

  The ACM sensor 1 has a detection unit 5 having a circular shape as a whole with the substrate surface 2a exposed in a comb-like shape at a substantially central position of the substrate 2. When a water film is formed between the substrate surface 2a of the detection unit 5 and the conductive film 4 and the two are connected, a corrosion current is generated and can be measured with a measuring instrument. This corrosion current has a correlation with the amount of corrosion and can be used for quantitative evaluation of the corrosion rate.

  The corrosion evaluation method in the present embodiment is suitable for evaluating the corrosiveness of a mild environment such as indoors that is not directly exposed to wind and rain.

Conventionally, the ACM sensor 1 has been mainly used for evaluation targeting outdoor environments such as bridges and structures. In such harsh environments such as outdoors exposed to direct wind and rain, the amount of corrosion current is large and the output value of the ACM sensor 1 is also large. Therefore, the influence of the temperature on the accuracy of the ACM sensor 1 is small, and it was considered that the difference due to the difference in temperature hardly affects the prediction of the corrosion rate. Therefore, for example, as shown in FIG. 6, in the conventional parameter study, the environmental factor of temperature T (° C.) is not considered, and the ACM is calculated from the humidity RH (%) and the sea salt particle amount Ws (g / m ² ). Corrosivity was evaluated by calculating the output value (μA) of the sensor 1.

  However, for example, in a mild environment such as a packing box, a transport container, or an indoor environment that is not directly exposed to wind and rain, the corrosion current amount I is very small, and the output value of the ACM sensor 1 is small, so that the influence of temperature is large. Therefore, when the conventional parameter study is applied in such a mild environment, the accuracy of the corrosion current amount I is lowered, and there is a possibility that accurate corrosivity evaluation cannot be obtained.

  The corrosion evaluation method in the present embodiment has been made in view of the above points, and is a corrosion evaluation method for evaluating the corrosiveness of the environment, which includes temperature T, humidity RH, and sea salt particle amount Ws. Step S1 for obtaining a correlation with the corrosion current amount I of the ACM sensor in advance, Step S2 for measuring the environmental temperature T, the humidity RH, and the sea salt particle amount Ws, the measured temperature T, Step S3 for calculating the corrosion current amount I based on the humidity RH and the sea salt particle amount Ws.

[Step S1]
In step S1, a correlation among the temperature T, the humidity RH, the sea salt particle amount Ws, and the corrosion current amount I of the ACM sensor 1 is obtained in advance. 2 to 4 are examples of graphs showing correlations between the temperature T, the humidity RH, the sea salt particle amount Ws, and the corrosion current amount I of the ACM sensor 1, and FIG. No Ws, FIG. 3 shows the case where the sea salt particle amount Ws is 1 × 10 ⁻³ (g / m ² ), and FIG. 4 shows the case where the sea salt particle amount Ws is 1 × 10 ⁻² (g / m ² ). 4 is a graph showing a correlation between temperature T, humidity RH, and corrosion current amount I of ACM sensor 1.

The correlation between the temperature T, the humidity RH, the sea salt particle amount Ws, and the corrosion current amount I of the ACM sensor 1 is experimentally determined using the parameters of the temperature T, the humidity RH, and the sea salt particle amount Ws. Derived. For example, the temperature T is −30 ° C. to 80 ° C., the humidity RH is 1% to 100%, and the sea salt particle amount Ws is 0 (g / m ² ), 1 × 10 ⁻⁴ (g / m ² ), 1 × 10 ⁻³ (g / m ² ) and 1 × 10 ⁻² (g / m ² ) were set.

[Step S2]
In step S2, environmental temperature T, humidity RH, and sea salt particle amount Ws are measured. The temperature T and humidity RH of the environment are measured at predetermined time intervals (for example, every 10 minutes) in synchronism with the ACM sensor 1 by thermo-hygrometers (not shown) connected to measuring instruments (ACM loggers). It is done once.

The sea salt particle amount Ws is measured by a QCM (Quartz Crystal Microbalance) sensor (not shown), for example. The QCM sensor utilizes the fact that the resonance frequency of the crystal resonator changes due to the mass change on the electrode, and can detect a mass change of the order of 1 ng / cm ² . With the QCM sensor, the resonance frequency is measured before and after actual exposure, and the amount of deposits (sea salt particle amount) on the electrode surface can be obtained from the difference. The QCM sensor uses an Au electrode, but since Au does not corrode, the change in mass on the electrode to be measured becomes the amount of deposit (electrolyte + non-electrolyte), and the electrolyte is considered to be sea salt. Sea salt absorbs 5.5 times its own mass at a humidity of RH 90%, so the amount of adsorbed water is determined as the mass difference between the dry state and humidity RH 90%, and this is divided by 5.5 to obtain sea salt. The amount of particles can be measured.

[Step S3]
In step S3, the corrosion current amount I is calculated based on the correlation using the temperature T measured in step S2, the humidity RH, and the sea salt particle amount Ws. Conversion to the corrosion current amount I with respect to all the sea salt particle amounts Ws up to the sea salt particle amount 1 × 10 ⁻² (g / m ² ) can be performed using approximate equations, and the temperature T and humidity. If the RH and the corrosion current amount I are known, conversion to the sea salt particle amount Ws is possible. The following formula (1) is an approximate expression for converting a value between the amount of sea salt particles 1 × 10 ⁻³ (g / m ² ) and 1 × 10 ⁻⁴ (g / m ² ) into the amount of corrosion current I. It is an example.
logWs = 1 + Log (I [T, RH] / I [3, T, RH]) / Log (I [3, T, RH] / I [4, T, RH]) (1)
Where Ws: Sea salt particle amount
I [T, RH]: ACM sensor actual measurement (T: temperature, R: humidity)
I [3, T, RH]: Sensor output value at T and RH of 1 × 10 ^-3 (g / m ² )
I [4, T, RH]: 1 × 10 ^-4 (g / m ² ) sensor output value at T, RH

  According to the corrosion evaluation method in the present embodiment, the correlation between the environmental current RH and the sea salt particle amount Ws as well as the environmental temperature T is required, and the correlation with the corrosion current amount I is obtained. I can be calculated accurately, and the corrosiveness of the environment can be accurately evaluated. Therefore, it is possible to compare which environment is likely to rust in conducting an environmental survey of rusting ease. Then, the same environment as the environment surveyed can be reproduced in a test room or the like. It can also be used to examine packaging specifications for parts logistics, such as the presence or absence and use of desiccants and rust inhibitors.

<Second Embodiment>
Next, a second embodiment will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 5 is a diagram for explaining an embodiment of the humidity evaluation method. In the humidity evaluation method in the present embodiment, the ACM sensor 1 and the thermometer 11 are used.

  A predetermined amount of sea salt particles is attached to the detection unit 5 of the ACM sensor 1 (see FIG. 1). The ACM sensor 1 is provided with a cover member 6 having a cylindrical shape that covers the detection unit 5 from the outside. The lower end portion of the cover member 6 is fixed in a state of being in close contact with the ACM sensor 1 and sealed, and the detection portion 5 is exposed in the center hole of the cover member 6.

  The upper end portion of the cover member 6 is closed by a moisture permeable sheet 7. The moisture-permeable sheet 7 has a configuration that allows moisture to pass but does not allow sea salt particles to pass. The thermometer 11 is composed of, for example, a thermocouple. The output value of the thermometer 11 is input to a measuring instrument (ACM logger) not shown.

  In the humidity evaluation method in the present embodiment, the environment is set in advance in step S11 in which the correlation among the temperature T, the humidity RH, the sea salt particle amount Ws, and the corrosion current amount I of the ACM sensor 1 is obtained in advance. Step S12 for adjusting the sea salt particle amount Ws to be measured, step S13 for measuring the temperature T and the corrosion current amount I of the ACM sensor 1 under the environment, the measured temperature T and the ACM sensor 1 It includes a step S14 of calculating the humidity RH of the environment on the basis of the corrosion current amount I and the preset sea salt particle amount Ws.

[Step S11]
In step S11, a correlation among the temperature T, the humidity RH, the sea salt particle amount Ws, and the corrosion current amount I of the ACM sensor 1 is obtained in advance. Since the content of step S11 is the same as that of step S1 in 1st Embodiment, the detailed description is abbreviate | omitted.

[Step S12]
In step S12, processing for adjusting the environment to a preset amount of sea salt particles is performed. In the present embodiment, a predetermined amount of sea salt particles is attached to the detection unit 5 of the ACM sensor 1, and the outside is covered with the cover member 6, and moisture is passed by the moisture permeable sheet 7. Is configured not to pass. As a result, the environment is adjusted to a preset amount of sea salt particles.

[Step S13]
In step S13, the environmental temperature T and the corrosion current amount I of the ACM sensor 1 are measured. The temperature T is measured by the thermometer 11, and the corrosion current amount I is measured by the ACM sensor 1. The measurement result is recorded in an instrument (ACM logger).

[Step S14]
The correlation obtained in step S11 based on the temperature T measured in step S13, the corrosion current amount I of the ACM sensor 1, and the sea salt particle amount Ws adjusted in advance by being attached to the detection unit 5. Based on the above, the humidity RH is calculated.

  According to the humidity evaluation method in the present embodiment, since the environmental temperature RH and the sea salt particle amount Ws as well as the environmental temperature T are required, the correlation with the corrosion current amount I is obtained. It can be calculated with high accuracy and the environmental humidity can be accurately evaluated.

  For example, a conventional polymer film type hygrometer has an error as large as 10% to 15% in a high humidity region, but the ACM sensor 1 does not increase an error even in a high humidity region.

  Table 1 above shows the output value (corrosion current amount I) of the ACM sensor 1 and the humidity RH when the output variation of the ACM sensor 1 is ± 5%. The output variation of the ACM sensor 1 itself is managed within 5% at the time of calibration, and when converted to humidity RH using the parameter study from there, the error falls within 1%. Therefore, the humidity error of the hygrometer using the ACM sensor 1 is 1%, and the humidity can be calculated with high accuracy.

  Although the conventional polymer film type hygrometer cannot be used in the condensation region, the ACM sensor 1 can also be used in the condensation region. Therefore, the humidity evaluation method in the present embodiment can calculate the humidity in a wider environment.

  In addition, it is preferable that the humidity evaluation method in this Embodiment has the step which removes the oxide film currently formed in the board | substrate surface 2a of the ACM sensor 1 before step S12 which adjusts the amount of sea salt particles of an environment. . The removal of the oxide film can be performed by washing the substrate surface 2a with an acid. By removing the oxide film as a preparation for measurement, it is possible to prevent a decrease in sensitivity of the ACM sensor 1 due to the formation of the oxide film. Further, in the humidity evaluation method according to the present embodiment, when a plurality of ACM sensors 1 are used or when the same ACM sensor 1 is repeatedly used, variations in sensitivity of the ACM sensors 1 can be prevented.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ACM sensor 2 Board | substrate 3 Insulating film 4 Conductive film 5 Detection part 6 Cover member 7 Moisture permeable sheet 11 Thermometer

Claims (2)

A humidity evaluation method for evaluating environmental humidity,
Obtaining a correlation among temperature, humidity, sea salt particle amount, and corrosion current amount of the ACM sensor in advance;
Adjusting the environment to a preset amount of sea salt particles;
Measuring the temperature and the amount of corrosion current of the ACM sensor under the environment;
Calculating the humidity of the environment based on the measured temperature, the amount of corrosion current of the ACM sensor, and the preset amount of sea salt particles;
The humidity evaluation method characterized by including. 2. The method according to claim 1 , further comprising a step of removing an oxide film formed on a surface of the substrate of the ACM sensor with an acid before the step of adjusting the amount of sea salt particles in the environment. Humidity evaluation method.

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