JPS61294348A - Film diagnosing device - Google Patents

Abstract

PURPOSE:To diagnose the degradation state of a coated film without leading out leads from a foundation metal by arranging three or more cells incorporating power supply electrodes on the surface of the coated film and measuring the impedance between cells. CONSTITUTION:Three detecting probes consisting of metallic plates 3a, 3b, and 3c, electrolytic pastes 5a, 5b, and 5c and electrode holders 4a, 4b, and 4c are arranged on the coated film 2 of a steel plate 1, and impedances between individual probes are measured by an impedance measuring instrument 8. Impedances of the coated film under individual probes are calculated on the basis of measured results. Thus, the impedance of the coated film is measured without leading out the leads from the foundation steel plate 1 to diagnose the degree of the degradation of coated film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating diagnosis device for diagnosing the corrosion protection state of a painted structure.

[Conventional technology]

Painting methods have been put into practice as a corrosion protection measure for ships and land structures, but since the coating film gradually deteriorates over time, if the state of deterioration could be easily diagnosed, it would be possible to prevent accidents caused by rusting on various structures. This makes it possible to predict and take appropriate anti-corrosion measures. To judge this deterioration, for example,
Impedance as shown in the figure, tan delta (tan
δ) is known. That is, in the figure, an electrode holder 4 made of an insulator, in which a metal plate 3 having an appropriate area is buried, is brought into close contact with the surface of the coating film 2 of the object to be measured, which is made up of a steel plate 1 and a coating film 2. The AC resistance between the lead end 6 of the steel plate 1 and the lead end 7 of the steel plate 1 is measured by a measuring device 8. Here, 5 is for reducing the resistance between the metal plate 3 and the coating film 2.

It is an electrolyte paste filled with electrolyte components such as potassium chloride and polymeric alcohol or agar.

[Problem that the invention seeks to solve]

The disadvantage of such conventional measurement methods is that it is necessary to take the lead 7 from the steel plate 1, which is the base metal plate of the object to be measured, and a part of the coating film 2 must be peeled off at 9 o'clock. That's true.

In addition, the internal resistance of the coating film 2 is high, and the object to be measured is a ship,
In actual equipment such as structures, complete or incomplete earthing9
However, there is a leakage resistance floating voltage, and commercially available bridge type one-phase detection systems have the disadvantage of poor accuracy, sensitivity, and reliability of the obtained results.

The present invention was made in view of the above-mentioned problems of the conventional method, and it is possible to accurately and easily diagnose the deterioration state of each measurement position of the coating film 20 without peeling off the coating film 2 and exposing the base metal 1. The purpose is to provide a film diagnostic device that can perform

[Next method to solve the problem]

Therefore, the present invention is directed to a current-carrying electrode disposed on the coating surface. three or more built-in cells and an AC power supply provided between the cells to apply an AC voltage between the abutting coatings of the cells;
The gist of the present invention is to provide a film diagnostic device including impedance measuring means provided between the cells to measure the total impedance between the cells.

[Effect]

Generally, films such as paint films deteriorate as time passes from the time of application, with cracks and cavities appearing in the film. Therefore, if an AC voltage is applied to a certain point and the impedance is measured, the eddy current will change due to cracks and cavities in the coating where deterioration has occurred, and the impedance will also change, so by knowing this impedance, The degree of deterioration of the film can be seen.

The present invention uses an AC power source to form an electrical circuit from one cell and coating through the metal base material to the other coating and cell, and then to the first cell.

The degree of deterioration of the two coatings is diagnosed by measuring the impedance of the two coatings.

Therefore, since the current that enters from one cell through one coating returns to the other cell through the other coating, it is necessary to remove the coating and connect the lead wire directly to the metal base material. There's no need. Also, install in 3 or more Ce/Le locations.

By measuring the impedance, the impedance of each installation location can be obtained, and the degree of deterioration can be diagnosed for each installation location.

〔Example〕

The present invention will be described in detail below with reference to embodiments shown in the drawings.

FIG. 1 is an explanatory diagram of one embodiment according to the present invention. In this embodiment, three detection probes each using a metal plate 3 having different natural electrode potentials as electrodes are mounted on a coating film 2 applied to a steel plate 1, and these three detection probes have impedances equipped with an AC power supply. Two wires were connected alternately to the measuring device 8 to enable total impedance measurement. Here, the detection globe is a metal plate 3a so as to be parallel to the surface of the coating film.

3b, 3C%r, electrode holders 4a, 4b, respectively.

4 and c are filled with internal chemical paste 5. The arrangement of the detection probe is shown in Figure 2 (a).
It is also possible to arrange them in a straight line like this.

If the electrical resistance of the steel plate 1 becomes a problem.

As shown in Figure 2(b), the distance between the three detection probes is
An even arrangement is preferred.

By using the impedance Z-2 measured by the device configured as described above, it is possible to obtain individual impedances at each measurement point, rather than a composite value of impedances as in a linear equation.

First, the impedance Z between each detection probe is expressed by the following equation.

Zab + jWab = Ra + jXa + R
b + jxb - (1) Zbc + jWbc = R
b + jXb+Rc + jXc...-(2) Zca
+jWca = Rc 1jXc+Ra + jXa
...(3) where Zab: Real term of impedance between terminals a and b jWab: Imaginary term of impedance between terminals a and b Ra: Real term of impedance of the coating under terminal a jXa: Real term of impedance between terminals a and b Imaginary term of film impedance 5uffixa, b, c: each terminal a, b, c2
As expected.

From the above equations (1) to (3), the real number term is Zab = Ra + Rb - (4) Zbc = R
h + Rc...(5) Zca = Rc + Ra
...As shown in (6), Zab, Zbc, and Zca are arranged using actual measured values, and from these formulas, Ra, Rb,
Rc2 can be found.

Rc-(-Zab+Zbc+Zca)=(9)-2- Similarly, the imaginary term can be found using the following equation.

jXa =-2-(jWab -jWbc
) −= (10)jXb = T(jWab +
jWbc−jWca) −・−(11)jXc =−T
-(-jWab 1jWbc + jWca)-(12
) In this way, with three sensing probes, it is possible to obtain individual impedances at each measurement point, rather than one composite value.

In the above embodiment, electrolytic paste 5 is used as the detection probe.
The electrodes on the metal plate 3 were used.

In addition to the above methods, a simple method such as pressing a certain area of metal foil, conductive plastic film, etc. directly onto the painted surface may also be used. Also, as an indication of impedance, CoL
The e-cote display, Ra+jXat direct display, direct display, or direct output to the combiator for analysis may be performed as appropriate.

In addition, in this disaster example, the number of detection probes was three, but since a multi-structure with four or more probes would complicate the device, it is preferable to use the device while moving it on a device equipped with three detection probes.

〔Effect of the invention〕

As described above, in the present invention, there is no need to take lead wires from the underlying metal, and the condition of each point on the coating can be efficiently diagnosed at three locations at the same time without peeling off the coating. Therefore, it is possible to contribute to countermeasures against damage to structures caused by nine-shot rust, and to perform an extremely effective diagnosis from an economical and safety standpoint.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a film diagnostic device according to an embodiment of the present invention, FIGS. 2(a) and (b) are schematic explanatory diagrams explaining the arrangement of detection probes, and FIG. 3 is a diagram of a conventional method. It is an explanatory diagram. 1... Steel plate, 2... Paint film, 3... Metal plate, 8...
・Impedance measuring instrument. 1st against 1st

Claims (1)

[Claims] (1) Three or more cells with built-in current-carrying electrodes disposed on the film surface, an AC power supply provided between the cells to apply an AC voltage between the cells and the film in contact with the cells, and A film diagnostic device comprising an impedance measuring means provided between the cells to measure the impedance of the cell.