JPH06102218A - Measuring method for deterioration of coating film - Google Patents

Abstract

PURPOSE:To obtain a method for measuring the deterioration of a coating film whereby the impedance is measured in a short time even when a plurality of points are to be measured. CONSTITUTION:An electrode and a member for impregnation of gel are accommodated in a case 12, thereby to form an impedance measuring probe 11. A gel penetration probe 20 is provided by accommodating a gel impregnation member within a case 12(a). Gel penetration probes 20 are nearly concurrently set at a plurality of measuring points to allow a conductive gel to penetrate therethrough. Thereafter, the gel penetration probe 20-a is exchanged with the impedance measuring probe 11 to measure the impedance of the measuring point. Then, the gel penetration probe 20-b is exchanged with the impedance measuring probe 11 thereby to measure the impedance of the measuring point. In this manner, by sequentially exchanging the gel penetration probe 20 with the impedance measuring probe 11, the impedance of the respective measuring points is sequentially measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film deterioration measuring method for electrochemically detecting deterioration of a coating film applied to the surface of a base metal.

[0002]

2. Description of the Related Art As a coating film deterioration measuring method, there is a method of measuring the impedance of the coating film and diagnosing the degree of deterioration of the coating film from the measured impedance. Less than,
An outline of this type of coating film deterioration measuring method will be described.

First, the impedance of the coating film is measured by the method shown in FIG. That is, the lower surface of the gel impregnating member 1 impregnated with the conductive gel is brought into close contact with the coating film A, and the upper surface of the gel impregnating member 1 is brought into close contact with the electrode 2 made of aluminum foil or the like. Then, the AC power supply 3 applies an AC voltage between the base metal B coated with the coating film A and the electrode 2,
The current value and the voltage value at this time are read from the ammeter 4 and the voltmeter 5, respectively, and the impedance of the coating film A is determined from these measured values.

In a normal state immediately after coating, the electric resistance of the coating film A is very large and has a value of 10 ⁸ (Ω / cm) or more. The electrical equivalent circuit of the coating film A is as shown in FIG. As shown in, it is represented by a parallel circuit of a resistor Rf and a capacitor Cf. However, when the coating film A deteriorates, such a simple equivalent circuit exhibits a complicated impedance having a plurality of time constants. Therefore, by utilizing this property, the degree of deterioration of the coating film A can be diagnosed. can do.

Two methods for diagnosing the degree of deterioration of the coating film A will be described below. First, as shown in FIG. 9, the first is to create a so-called Bode diagram by plotting the absolute value of the impedance Z of the coating film A against the frequency f (logarithm) of the AC power supply 3. is there. In the figure, a is a curve when the coating film A is normal, and b is a curve when the coating film A is deteriorated. Comparing the curves a and b, the impedance Z of the low frequency side is The difference is remarkable. Therefore, from this fact, the degree of deterioration of the coating film A can be diagnosed (as is clear from FIG. 9, when the deterioration of the coating film A is detected only from the absolute value of the impedance Z, the frequency f It is more effective to measure on the lower side of.

The second is a method for creating a so-called Nyquist diagram by expressing the real part and the imaginary part of the impedance of the coating film A on a complex plane as shown in FIG.
In the figure, c is a locus when the coating film A is normal, d
Is a locus when the coating film A is deteriorated, and the locus d has a smaller radius than the locus c and is slightly deformed. Therefore, the degree of deterioration of the coating film A can be estimated from this.

In the above measuring method, in order to perform accurate measurement, it is necessary to bring the gel impregnating member into close contact with the coating film and allow the conductive gel to permeate the measurement site of the coating film. is there. However, when the coating film has irregularities, it is difficult to bring the gel impregnating member into close contact with the coating film, and therefore, the following is proposed in Japanese Patent Application No. 1-105839. There is.

That is, in FIG. 11, an electrode 7 made of tin foil is attached to the inner surface of the case 6, and a connection terminal 8 is connected to the electrode 7. In addition, a sponge-like gel impregnating member 9 impregnated with a conductive gel is accommodated in the case 6, and a magnet 10 is used to hold the case 6 during measurement.
Is fixed to the base metal. In this case, even if the coating film has irregularities, the convex surface portion 9a of the gel impregnating member 9 absorbs the irregularities and adheres to the coating film, so that the conductive gel can penetrate into the coating film.

[0009]

By the way, FIG.
It shows how the conductive gel permeates the coating film, and is the result of an experiment using the apparatus shown in FIG. 11. In this case, the horizontal axis represents the time (standing time) during which the gel impregnating member 9 is kept in close contact with the coating film, and the vertical axis represents the coating film impedance Z (logarithm) at a frequency of 0.1 Hz. As is clear from the figure, the device is left for one hour or more until the curve becomes flat and the impedance becomes stable, that is, until the conductive gel permeates after setting the device on the coating film. There is a need.

For this reason, when measuring the impedance at a plurality of points on the coating film, it is necessary to set the device on the coating film and leave it for one hour or more each time the measurement is performed. It takes time. Moreover, the degree of permeation of the conductive gel into the coating film depends on the surrounding temperature and humidity, so if the measurement takes a long time, the temperature and humidity will change over time and the measurement conditions will vary. , The measurement accuracy will decrease.

The present invention has been made in view of the above circumstances, and an object thereof is deterioration of a coating film which can be measured in a relatively short time even when there are a plurality of measured portions of the coating film. To provide a measuring method.

[0012]

The invention according to claim 1 is
Between the one end surface of the gel impregnated member impregnated with the conductive gel is adhered to the coating film, the other end surface of the gel impregnated member is adhered to the electrode, and between the base metal coated with the coating film and the electrode. By measuring the impedance of the coating film by applying an AC voltage to the, coating film deterioration measuring method for diagnosing the degree of deterioration of the coating film from the impedance, the electrode and the gel impregnating member is housed in a case. An impedance measurement probe and a plurality of gel permeation probes having the gel impregnating member housed in a case are used, and the gel permeation probe is set at each of a plurality of measurement sites in the coating film. Then, the conductive gel is permeated, and then the gel permeation probe is sequentially replaced with the impedance measurement probe, and the impedance of each measured site is changed. Characterized in was such that the next measurement.

According to a second aspect of the invention, the conductive gel is impregnated.
One end surface of the gel impregnated member adhered to the coating film,
The other end surface of the gel impregnating member is adhered to the electrode, and the coating film is
AC voltage is applied between the applied base metal and the electrode
The impedance of the coating film is measured by
The degree of deterioration of the coating film is diagnosed from the impedance of
In the coating film deterioration measurement method, the electrode can be attached and detached.
A plurality of chambers containing the gel permeation probe inside
Multiple measuring points on the coating film using a probe for
Each of the dual-purpose plugs without the electrodes attached
Set the lobe to penetrate the conductive gel, then
Attach these electrodes to each dual-purpose probe in sequence and
The impedance of a fixed part is measured sequentially.
It has special characteristics.

According to the second aspect of the present invention, the case is composed of the cylindrical body and the lid removably fitted in the upper opening of the cylindrical body, and the electrode is attached to the lower surface of the lid. Therefore, the electrode may be detachable from the case (the invention according to claim 3).

[0015]

According to the first aspect of the present invention, first, a gel permeation probe is set in each of a plurality of measurement sites to permeate the conductive gel, and then the gel permeation probes are sequentially placed in the impedance measurement probe. By exchanging with, the impedance of each measurement site is sequentially measured. Therefore, each time the impedance is measured, the device is set at the site to be measured and left for a predetermined time, so that the device can be left for a shorter time, and as a result, the measurement can be performed in a short time. You can

According to the second aspect of the present invention, first, the combined probe with no electrodes attached is set in each of the plurality of sites to be measured to permeate the conductive gel, and then the combined probe is used. The electrodes are sequentially attached, and the impedance of each measurement site is sequentially measured. Therefore, it is possible to shorten the leaving time of the device as compared with the conventional one, and as a result,
The measurement can be performed in a short time. Moreover, since the case of the dual-purpose probe remains fixed to the coating film,
There is no possibility of misalignment between the site where the conductive gel penetrates and the site where the impedance is measured, and the impedance of the site to be measured can be reliably measured.

Further, in the invention according to claim 3, a case is composed of a cylindrical body and a lid removably fitted in an upper opening of the cylindrical body, and an electrode is attached to a lower surface of the lid. Therefore, the electrode can be attached to and detached from the case with a relatively simple structure.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, the impedance measurement probe 11 will be described with reference to FIG. That is, the electrode 13 made of tin foil is provided on the ceiling surface of the case 12.
Is attached, and the electrode 13 is connected to the connection terminal 14 provided on the upper surface of the case 12. A sponge-like gel impregnating member 15 is housed in the case 12. The gel impregnating member 15 is impregnated with a conductive gel, and when the case 12 is pressed against the coating film A (see FIG. 1), the convex portion 16 of the gel impregnating member 15 absorbs the irregularities of the coating film A. It deforms so that it adheres to the coating film A. Further, a female thread portion 17 is provided on the outer peripheral surface of the case 12, and a guide ring 19 having a magnet 18 is screwed into the female thread portion 17.

Next, the gel permeation probe 20 will be described with reference to FIG. That is, the gel permeation probe 2
0 indicates the electrode 1 from the impedance measurement probe 11.
3, the connection terminal 14 is removed, the case 12
Gel impregnation member 1 in which conductive gel is impregnated in (a)
5 (a) is accommodated, and the female thread portion 17 of the case 12 (a) is accommodated.
A guide ring 19 having a magnet 18 (a) in (a)
(A) is screwed together.

On the other hand, in FIG. 1, the impedance measuring means 21 comprises an AC power supply 21a, an ammeter 21b and a voltmeter 21c.
By applying an AC voltage between the base metal B and the electrode 13, the current value and the voltage value at this time are respectively measured by the ammeter 21.
b and the voltmeter 21c are read, and the impedance of the coating film A is determined from these measured values.

Next, the impedance measuring probe 11
A method for measuring the impedance of the coating film A using the gel permeation probe 20 will be described. First, as shown in FIG. 1, a gel permeation probe 20 is fixed to each of a plurality of measurement sites in the coating film A by a magnet 18 (a) at substantially the same time, and the convex surface of the gel impregnating member 15 (a) is fixed. The portion 16 (a) is brought into close contact with the coating film A. Then, it is left as it is for a predetermined time to allow the conductive gel to penetrate into the coating film A,
By removing the magnet 18 (a) from, for example, the gel permeation probe 20-a is removed. Next, the impedance measuring probe 11 is fixed to the measurement site by the magnet 18, and the gel permeation probe 20-a is replaced with the impedance measuring probe 11. After that, an AC voltage is applied between the base metal B and the electrode 13 by the AC power supply 21a to measure the impedance of the measurement site.

Next, for example, the gel permeation probe 20-
Replace b with the impedance measuring probe 11,
The impedance of the gel permeation probe 20 is measured by measuring the impedance of the measurement site, then replacing the gel permeation probe 20-c with the impedance measurement probe 11, and measuring the impedance of the measurement site. The measurement probe 11 is sequentially replaced, and the impedance of each measurement site is sequentially measured. Then, based on the measured impedance, a Bode diagram (see FIG. 9) and a Nyquist diagram (see FIG. 10) are created to diagnose the deterioration of the coating film A.

According to the first embodiment described above, the following effects can be obtained. That is, the gel permeation probe 20 is set to each of the plurality of measurement sites to permeate the conductive gel, and then the gel permeation probe 20 is sequentially exchanged with the impedance measurement probe 11, and each measurement site is measured. Since the impedance is measured sequentially, the time for leaving can be shortened as compared with the conventional method in which the case is set on the coating film and left for a predetermined time each time the impedance is measured. As a result, the measurement can be performed in a relatively short time, and the measurement can be performed under a substantially constant measurement condition such as temperature and humidity, so that the measurement accuracy is improved.

By the way, conventionally, in order to shorten the standing time and shorten the measurement, it is considered to prepare a plurality of devices shown in FIG. 11 and set the devices to each of a plurality of measured parts. To be However, since the device shown in FIG. 11 has an impedance measuring function (electrode 7 etc.), it is relatively expensive, and the cost is high if a plurality of devices are prepared. In this respect, in the above-described first embodiment, the prepared gel permeation probe 20 does not include the electrode 13, and only the gel impregnating member 15 (a) is housed in the case 12 (a). Since it has a simple structure, it is relatively inexpensive, and the cost is not expensive even if multiple units are prepared.

In the first embodiment, when the gel permeation probe 20 is replaced with the impedance measurement probe 11, the gel permeation probe 2 starts from the coating film A.
Although 0 was removed together with the guide ring 19 (a), it may be carried out as follows. That is, only the case 12 (a) is removed from the coating film A by screwing off the case 12 (a) of the gel permeation probe 20 from the guide ring 19 (a). Then, the case 12 of the impedance measuring probe 11
The guide ring 19 is unscrewed from, and the case 12 is screwed to the guide ring 19 (a) fixed to the coating film A.

In this way, the gel permeation probe 20 is used.
When the probe is replaced with the impedance measuring probe 11, there is no possibility of positional displacement between the site where the conductive gel is permeated and the site where the impedance is measured, and the impedance of the site to be measured is reliably measured. Can be measured.

Next, a second embodiment of the present invention will be described with reference to FIGS. First, referring to FIG.
The dual-purpose probe 22 will be described. That is, the case 23
Is a tubular body 24 and a lid 2 fitted in an upper opening of the tubular body 24.
It is composed of 5 and. In this case, a concave portion 26 is formed in the cylindrical body 24, and a convex portion 27 is formed in the lid 25. When the lid 25 is pushed into the upper surface opening of the cylindrical body 24, the concave portion 26 is formed.
The convex portion 27 is fitted to, and the lid 25 is attached to the cylindrical body 24. Then, when the lid 25 is pulled up, the convex portion 27 becomes the concave portion 26.
And the lid 25 is removed from the tubular body 24. Also,
A sponge-like gel impregnating member 29 having a convex portion 28 is accommodated in the case 23, the gel impregnating member 29 is impregnated with a conductive gel, and a magnet 30 is provided on the lower end surface of the case 23. Is buried.

Further, in FIG. 6, the lid 25 (a) is the same as the lid 25 and has a convex portion 27 (a) to be fitted into the concave portion 26 of the cylindrical body 24. It is detachable from the body 24. Then, an electrode 31 made of tin foil is attached to the lower surface of the lid 25 (a), and a connection terminal 32 is connected to the electrode 31, and the electrode 31 is
It is attachable to and detachable from the case 23.

Next, a method of measuring the impedance of the coating film A using the lid 25 (a) and the plurality of dual-purpose probes 22 will be described. First, as shown in FIG. 4, the dual-purpose probe 22 is attached to each of the plurality of measurement sites on the coating film A.
Are fixed at approximately the same time by a magnet 30, and the convex surface portion 28 of the gel impregnating member 29 is brought into close contact with the coating film A. Then, it is left as it is for a predetermined time to allow the conductive gel to penetrate into the coating film A, then, for example, the lid 25 is removed from the dual-purpose probe 22-a, and the lid 25 is attached to the cylindrical body 24 of the dual-purpose probe 22-a.
The electrode 31 is mounted by mounting (a). After that, an AC voltage is applied between the base metal B and the electrode 31 by the AC power supply 21a of the impedance measuring means 21 to obtain the impedance of the coating film A.

Next, for example, the lid 25 of the dual-purpose probe 22-b is replaced with the lid 25 (a) to measure the impedance of the measurement site, and then the lid 25 of the dual-purpose probe 22-c is closed. 25 (a) and measure the impedance of the site to be measured.
The lid 25 (a) is sequentially attached to the device 2, and the impedance of each measurement site is sequentially measured.

According to the second embodiment described above, the combined probe 22 is set in each of the plurality of measurement sites to allow the conductive gel to permeate, and then the combined probe 22 is sequentially fitted with the lid 25 (a). As described above, the impedance of each measurement site is sequentially measured. Therefore, as in the first embodiment, the combined probe 22 can be left for a shorter period of time than in the conventional case. As a result, the measurement time can be shortened and measured. The accuracy can be improved. Moreover, the case 24 of the dual-purpose probe 22 has the coating film A.
Since it remains fixed at the position, there is no possibility of misalignment between the site where the conductive gel is permeated and the site where the impedance is measured, and the impedance of the site to be measured can be reliably measured. .

Further, the case 23 is provided with a cylindrical body 24 and a cylindrical body 2.
4 and a lid 25 (a) that is detachably fitted to
Since the electrode 31 is attached to the lower surface of the lid 25 (a), the electrode 31 can be attached to and detached from the case 23 with a relatively simple structure. Further, in this case, since the dual-purpose probe 22 that needs to be prepared in a plurality has a simple structure in which the gel-impregnating member 29 is housed in the case 23, it is relatively inexpensive, and it is expensive to prepare a plurality. It won't catch over.

In the first and second embodiments, the impedance measuring probe 11 and the lid 25 are used.
Although one is used for each of (a), for example, when there are three persons, the impedance measurement probe 11 is used.
And three lids 25 (a) are used,
Impedance measurement probe 1 according to the number of measurers
By adjusting the number of 1 and the number of lids 25 (a), the measurement time can be shortened more effectively.

In both of the above embodiments, the impedance measuring means 21 is composed of an AC power source 21a and an ammeter 21.
b, and a voltmeter 21c.
The personal computer may be provided with a CPU, a memory, an FDD, a display, etc., and the degree of deterioration of the coating film A may be automatically measured by a program written in the FDD.

[0035]

As is apparent from the above description, the coating film deterioration measuring method of the present invention has the following excellent effects.

According to the first aspect of the present invention, an impedance measuring probe and a plurality of gel permeation probes are used, and the gel permeation probe is set at each of a plurality of measurement sites in the coating film to make the electroconductive film conductive. The gel is permeated, and thereafter, the gel permeation probe is sequentially replaced with the impedance measurement probe, and the impedance of each measurement site is sequentially measured. Therefore, the measurement is performed within a relatively short time. It is possible to improve the measurement accuracy.

According to the second aspect of the present invention, a dual-purpose probe in a state where no electrode is attached is set in each of the plurality of measurement sites in the coating film to allow the conductive gel to penetrate,
After that, the electrodes were sequentially attached to each dual-purpose probe and the impedance of each measurement site was sequentially measured, so that the measurement can be performed in a relatively short time and the measurement accuracy is improved. Moreover, the impedance of the site to be measured can be reliably measured without causing a positional deviation between the site where the conductive gel penetrates and the site where the impedance is measured.

According to the invention of claim 3, the case is
It consists of a cylinder and a lid that is detachably fitted to the upper opening of the cylinder, and the electrode is attached to the lower surface of this lid, so the electrode can be attached to and detached from the case with a relatively simple structure. You can

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing an impedance measuring probe.

FIG. 3 is a view corresponding to FIG. 2 showing a gel permeation probe.

FIG. 4 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 2 showing a dual-purpose probe.

FIG. 6 is a view showing a state in which electrodes are attached to the dual-purpose probe.
Corresponding figure

FIG. 7 is a schematic diagram showing in principle the impedance measurement configuration of a coating film.

FIG. 8 is an electrical equivalent circuit diagram of the coating film.

[Figure 9] Bode diagram

Fig. 10 Nyquist diagram

FIG. 11 is a view corresponding to FIG. 2 showing the device of Japanese Patent Application No. 1-105839.

FIG. 12 is a characteristic diagram showing the relationship between the impedance of the coating film and the standing time.

[Explanation of symbols]

A is a coating film, B is a base metal, 11 is an impedance measuring probe, 12, 12 (a) is a case, 13 is an electrode, 1
5, 15 (a) is a gel impregnating member, 20 is a gel permeation probe, 22 is a dual-purpose probe, 23 is a case, 24 is a cylinder, 25, 25 (a) is a lid, 29 is a gel impregnating member, 3
Reference numeral 1 represents an electrode.

Claims (3)

[Claims] 1. A base metal coated with the coating film, wherein one end surface of a gel impregnating member impregnated with a conductive gel is adhered to a coating film and the other end surface of the gel impregnating member is adhered to an electrode. The impedance of the coating film is measured by applying an AC voltage between the electrode and the coating film deterioration measuring method for diagnosing the degree of deterioration of the coating film from the impedance, wherein the electrode and the member for gel impregnation are used. An impedance measurement probe housed in a case and a plurality of gel permeation probes housed in the case for the gel impregnating member are used, and each of the plurality of measured sites in the coating film contains the gel. Set a probe for permeation to permeate the conductive gel,
After that, the gel permeation probe is sequentially replaced with the impedance measurement probe, and the impedance of each measurement site is sequentially measured. 2. A base metal coated with the coating film, wherein one end surface of a gel impregnating member impregnated with a conductive gel is brought into close contact with a coating film, and the other end surface of the gel impregnating member is brought into close contact with an electrode. The impedance of the coating film is measured by applying an alternating voltage between the electrodes, and in the coating film deterioration measuring method for diagnosing the degree of deterioration of the coating film from the impedance, the electrode is placed in a detachable case. Using a plurality of dual-purpose probes accommodating the gel permeation probe, a plurality of measurement sites in the coating film, permeate the conductive gel by setting the dual-purpose probe in a state in which the electrode is not attached Then, after that, the electrodes are sequentially attached to each of the dual-purpose probes, and the impedance of each measurement site is sequentially measured. 3. A case is composed of a cylindrical body and a lid detachably fitted to an opening of an upper surface of the cylindrical body, and an electrode is attached to a lower surface of the lid so that the electrode is attached to the case. The coating film deterioration measuring method according to claim 2, wherein the method is detachable.