JPH04218757A - Method for diagnosing deterioration of film - Google Patents

Abstract

PURPOSE:To quantitatively, objectively and accurately diagnose the deterioration degree of a film in a method for diagnosing the deterioration degree of the film on the basis of the measured result of the impedance of the film. CONSTITUTION:Voltage with frequency of 0.01-1Hz is applied between a probe 10 and the substrate metal of a film 9 by an I/F board and a CPU 2 calculates the impedance of the film to each frequency from the current value measured by a preamplifier 12. The impedance of the film markedly changes within the frequency range of 0.01-1Hz with the elapse of time and the logarithm of the impedance of the film has linear relation with respect to the elapse of time and a judging means can judge the deterioration degree of the film 9 with high accuracy.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing paint film deterioration for objectively determining the degree of deterioration of a paint film.

0003

[Prior Art] Equipment placed outdoors, such as transformers and switchboards, is painted for corrosion protection and aesthetic purposes.
The coating deteriorates over time due to the effects of UV rays and moisture. If this type of paint film deterioration is left untreated, it will eventually lead to the paint film peeling off and rusting due to corrosion of the underlying metal, so in order to maintain the equipment, it is necessary to repaint it at an appropriate time and install a new one. It is necessary to form a coating film. If the timing of repainting is too early, it will be an economic waste; on the other hand, if it is too late, the underlying material will corrode and it will take more time to repair, which will increase the economic burden and have a negative impact on the maintenance of the equipment. . Therefore, conventionally, in this type of equipment, the degree of deterioration of the paint film is periodically diagnosed to determine the appropriate time for repainting.

[0004] It is desirable that this type of diagnosis be made as objectively as possible so that an appropriate judgment can always be made no matter who makes the diagnosis. Conventional general paint film deterioration diagnosis methods that take this point into consideration include the following. Peeling, cracking,
Prepare in advance a large number of sample photos of various deterioration conditions such as blistering, rust, etc., with the degree of deterioration varying in stages.
An operator compares and observes the actual paint film to be diagnosed and these sample photographs.

[0005] Then, the operator determines at what stage the actual state of the paint film matches the sample photo for each type of deterioration, and also assigns predetermined scores for each type of deterioration and degree of deterioration. and add these sequentially. When the total score reaches the standard value, it is determined that it is time for repainting or repair painting.

[0006] There is also the following method which seems to be a step ahead. This method utilizes the fact that the impedance of the coating film changes depending on the degree of deterioration of the coating film, and is described in detail in, for example, Japanese Patent Application Laid-open No. 102148/1983 filed by the present applicant. The procedure for diagnosing paint films that is actually adopted using this type of method is outlined below. First, an impedance measuring meter is brought to the site, the probe is placed on the surface of the paint film, a voltage of a specific frequency is applied between the probe and the underlying metal, and the paint film is measured based on the flowing current and voltage. Take a reading of the impedance from the meter.

[0007] Next, refer to the table prepared in advance to check which column of the resistive and capacitive impedance values for the frequencies recorded in this way correspond to. , based on which the degree of deterioration is determined. Note that the impedance measurement frequency in this case is 2
00Hz, 500Hz, and 1KHz were common.

[0008]

[Problem to be Solved by the Invention] However, in the former method of comparing and observing the actual paint film and a sample photo, the judgment itself as to whether or not it matches the sample photo is easily influenced by the subjectivity of the observer. There is no guarantee that anyone can always make an appropriate diagnosis. For this reason, the diagnostic results tend to be ignored, and repainting or repair painting may not be performed at an appropriate time. In addition, this method requires comparative observation with many sample photos, totaling of scores, etc., which is cumbersome and may lead to calculation errors.

On the other hand, in the method of using an impedance measuring meter, there is still room for subjectivity to enter into the reading of the meter, etc.
Furthermore, the task of comparing the measured values with evaluation standards was troublesome.

The present invention has been made in view of the above circumstances, and its purpose is to be able to quantitatively, objectively, and accurately diagnose the degree of deterioration of a paint film based on the measurement of paint film impedance. The present invention provides a method for diagnosing paint film deterioration.

[Configuration of the invention]

0012

[Means for Solving the Problems] The method for diagnosing paint film deterioration of the present invention involves applying a voltage containing a plurality of different frequencies between a base metal of the paint film and a probe directed to the surface of the paint film. means, current measuring means for measuring the current flowing through the coating film, and determining means for determining the degree of deterioration of the coating film based on the coating film impedance for each frequency calculated from the measurement results of the current measuring means. The present invention is characterized in that the measurement frequency of the coating film impedance is set in the range of 0.01 Hz to 1 Hz.

[0013]

[Operation] When a voltage including a plurality of different frequencies is applied between the base metal and the probe by the voltage applying means, a current flows through the coating film in the probe and is measured by the current measuring means. Here, the impedance of the coating film has a correlation with the degree of deterioration of the coating film. That is, the coating film impedance can be expressed by an equivalent circuit consisting of a parallel circuit of a resistor and a capacitor, and as the coating film deteriorates, its resistance value decreases and the impedance changes. Therefore, the determination means can objectively and quantitatively diagnose the degree of deterioration of the paint film through a predetermined analysis procedure.

In this case, by applying voltages containing a plurality of different frequencies to the coating film, the relationship between the frequency and the measured coating film impedance can be investigated, thereby increasing the reliability of the measurement data of the coating film impedance. You can confirm the gender.

[0015] If the deterioration state of the paint film is diagnosed using the paint film impedance at a frequency in the range of 0.01 Hz to 1 Hz, the degree of deterioration of the paint film or the remaining life of the paint film can be accurately determined. It is possible. That is, according to the experiments and research conducted by the present inventors, the coating impedance changes significantly over time in this frequency range, and the logarithm of the coating impedance is
They found that there is a linear relationship with the passage of time.

[0016] Since the coating impedance changes significantly over time, highly accurate impedance measurement can be performed. If the logarithm of the coating film impedance and time have a linear relationship, the degree of deterioration can be easily and accurately analyzed. On the other hand, in the high frequency range exceeding 1 Hz, the coating impedance does not change much over time, and at frequencies below 0.01 Hz, the measured value becomes unstable and the measurement takes time. This will end up costing you a lot of money.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, with reference to FIG. 1, a description will be given of an apparatus having both a coating film impedance measurement function and a coating film deterioration diagnosis function used in this embodiment.

That is, 1 is a so-called laptop-type or book-type personal computer,
Inside the main body case (not shown), CPU2, ROM3, R
It has a general configuration that includes an AM4, an FDD (floppy disk drive) 5, etc., as well as a liquid crystal display 6 and a keyboard 7. In the expansion slot of this personal computer 11, a D/A
An I/F board 8 having a conversion function and an A/D conversion function is inserted.

On the other hand, a probe 10 is applied to the surface of the coating film 9 on which deterioration diagnosis is to be performed. This probe 10 is known to have various structures (e.g., Japanese Patent Laid-Open No. 108954/1989), so it is not shown in detail, but basically it has a sponge-like electrode impregnated with conductive gel inside the main body container. The main container has a permanent magnet around the opening, and the sponge-like electrode is brought into close contact with the surface of the coating film 9 by the attractive force acting between the permanent magnet and the base metal 11. It has become.

A lead wire led out from the probe 10;
The lead wire connected to the base metal is connected to a preamplifier 12, and this preamplifier 12 generates a voltage signal corresponding to the current flowing through the coating film 9 when a voltage is applied between the probe 10 and the base metal 11. The signal is supplied to the I/F board 8 of the personal computer 1. With this, the preamplifier 12 passes through the coating film 9 to the probe 1.
It functions as a current measuring means for measuring the current flowing to zero. Note that the preamplifier 12 is capable of switching the measurement range depending on the degree of deterioration of the coating film 9, and in this embodiment, the impedance range is from 0.1 MΩ to 100 MΩ.
A range of MΩ (current: 0.01 μA to 10 μA) can be measured.

The I/F board 8 functions as a voltage applying means for applying voltages including a plurality of different frequencies between the probe 10 and the base metal 11, and the I/F board 8 functions as a voltage applying means for applying voltages including a plurality of different frequencies between the probe 10 and the base metal 11, and uses digital data stored in advance in the floppy disk. Based on the information, a voltage with a predetermined waveform generated and synthesized by the D/A conversion function of the I/F board 8 is output. The applied predetermined combined voltage waveform is 0.01H
z~1Hz, the power spectrum P is

[0022]

[Math 1]

From [0023]

[0024]

[Math 2]

It is made to exist between [0025] FIG. 2 shows an example of voltage waveforms synthesized so that the power spectrum P becomes P=1/f. Further, here, the phase of each frequency component constituting this voltage waveform is randomized to suppress the peak voltage as much as possible.

[0026] Also, the D/A conversion and A/F board 8
The timing with the D conversion is configured to be the same each time, so that the phase angle of the applied voltage and the current measurement phase angle of the preamplifier 12 are kept the same. Furthermore, the RAM of the personal computer 1
4 stores spectrum data of the output voltage waveform from the I/F board 8, which has been determined in advance. Thereby, the personal computer 1 calculates the impedance for each frequency from the current measurement result measured by the preamplifier 12 using an FFT (fast Fourier transform) program written in machine language.

Furthermore, as will be described later, the personal computer 1 functions as a determining means for diagnosing the degree of deterioration and remaining life of the paint film from the calculated paint film impedance. In this case, the coating film impedance can be expressed by an equivalent circuit consisting of a parallel circuit of a resistor and a capacitor, and the impedance changes by using the fact that as the coating film 9 deteriorates, its resistance value decreases and the impedance changes. Thus, the degree of deterioration of the coating film 9 can be diagnosed. In addition, to diagnose the degree of deterioration and remaining life of the paint film,
Among the calculated impedances, 0.01Hz to 1H
The impedance for a specific frequency (for example, 0.1 Hz) in the z range is used.

Next, a procedure for diagnosing the coating film 9 using the coating film deterioration diagnosing apparatus having the above configuration will be explained. This should clarify the functions performed by the personal computer 1.

First, the personal computer 1, preamplifier 12, and probe 10 are brought to a site where deterioration diagnosis is to be performed, and the probe 10 and the preamplifier 12 are connected to the surface of the coating film 9 as shown in FIG. And F.D.D.
Execute the measurement program in 5.

As a result of executing this program, probe 1
0 and the base metal 11, the current flowing through the coating film 9 at that time is detected by the preamplifier 12,
The voltage signal corresponding to the current is the personal computer 1
Since the voltage signal is applied to the I/F board 8 of
The signal is converted into a digital signal by the A/D conversion function of the /F board 8. Then, based on the data given from this I/F board 8, the CPU 2 calculates the coating film impedance for each frequency, and writes the results to a floppy disk in the FDD 5.

Such measurement of coating film impedance is carried out at a plurality of locations on the coating film 9, and in conjunction with this measurement, the type of coating film 9 at the time of measurement and the type of coating film 9 are entered from the keyboard 7 of the personal computer 1. Measurement data such as the film thickness and the area of the probe 10 are inputted and recorded on the floppy disk at the same time.

By the way, the coating film impedance can be expressed by an equivalent circuit consisting of a parallel circuit of a resistor and a capacitor, and as the coating film 9 deteriorates, its resistance value decreases and the impedance changes. . Therefore, the degree of deterioration of the paint film can be diagnosed objectively and quantitatively by a predetermined analysis procedure that will be described later.

Further, in this embodiment, as described above, the predetermined composite voltage waveform applied between the base metal 11 of the coating film 9 and the probe 10 includes a frequency range of 0.01 Hz to 1 Hz. , the power spectrum P is

[0034]

[Math 3]

From 0035

[0036]

[Math 4]

It is made to exist between [0037] In this case, by applying a voltage containing a plurality of different frequencies to the coating film 9, the relationship between the frequency and the measured coating film impedance can be investigated, as shown in FIG. The reliability of the measured data can be confirmed.

[0038] If the deterioration state of the paint film 9 is diagnosed using the paint film impedance with a frequency in the range of 0.01Hz to 1Hz, the degree of deterioration of the paint film 9 or the remaining life of the paint film can be accurately determined. It is possible to judge. That is, according to the experiments and research conducted by the present inventors, as shown in FIG. They found that there is a linear relationship with progress.

[0039] Since the coating impedance changes significantly over time, highly accurate impedance measurement can be performed. If the logarithm of the coating film impedance and time have a linear relationship, the degree of deterioration can be easily and accurately analyzed. On the other hand, in the high frequency range exceeding 1 Hz, the coating impedance does not change much over time, and at frequencies below 0.01 Hz, the measured value becomes unstable and the measurement takes time. This will end up costing you a lot of money.

Now, after the measurement using the probe 10 as described above is completed, the diagnostic program is then read out from the floppy disk and executed. The execution procedure of this diagnostic program is as shown in the flowchart of FIG.

Step S1: Reading measurement data First, the measurement data recorded on the floppy disk is read out, and the thickness of the coating film 9, the area of the probe 10, etc. at the time of measurement are displayed on the display 6 for confirmation. Ru. After this,
When the confirmation operation is performed, the display 6 becomes an initial condition input screen.

Step S2: Inputting initial conditions Here, codes representing the type of paint, age of use, external appearance, installation environment, etc. for diagnosing the deterioration state of the paint film are input from the keyboard 7.

Step S3: Smoothing The impedance measurement data is smoothed. This is because impedance data measured on site may not necessarily change uniformly with respect to each frequency, so measurement accuracy is improved by smoothing the data.

Step S4: Data analysis First, based on the smoothed impedance data, for example 0.1H
Determine the coating film impedance Z1 of z, and create a graph of the coating film impedance Z and Cx (capacitance component) for each frequency f to confirm whether the measurement conditions are appropriate.
indicate. This graph is as shown in FIGS. 7 and 8.

That is, since the coating film impedance Z is considered to be equivalent to a parallel circuit of a resistor and a capacitor, as shown in FIG. 7, when the coating film is in a normal state (indicated by A), the resistance component is infinite. As a result, logf and logZ
There is a linear relationship that slopes downward to the right. On the other hand, as the coating film 9 deteriorates, the resistance component decreases, so as shown in B and C of the same figure, logZ decreases in the low frequency range compared to A above and remains unchanged as a straight line. That part will arise.

Furthermore, as shown in FIG. 8, by creating a graph of the relationship between the frequency f and the capacitance component Cx, the state of corrosion of the base metal 11 can also be determined. That is, under normal conditions, Cx is a constant value for the frequency f, as shown by A in the figure, but due to the corrosion of the base metal 11, B
, C, the so-called electric double layer capacity increases.

Step S5: Repetition of analysis and determination of incorrect data Since the measurement of coating film impedance Z is performed at multiple locations for one device, the above data analysis is repeated for the number of measurement locations, and the data analysis at each measurement point is repeated. The average value and variance of the coating film impedance Z1 at 0.1 Hz are calculated, and abnormal data are excluded as erroneous data due to measurement errors or the like.

Step S6: Creating a life estimation diagram The logarithm logZ of the coating film impedance Z has a linear relationship with the time t. Further, the initial impedance Z0 corresponding to the paint type input in step S2 is stored as known data, and the number of years of use is input in step S2. Therefore, from this information, the logarithm logZ0 of the initial impedance Z0 and the measured coating film impedance Z1 are calculated as shown in FIG.
By connecting the logarithm of logZ1 with a straight line L,
You can draw a lifespan estimation diagram. Here, the remaining life tr refers to the time from the measurement time t1 to the point where the extension of the straight line L intersects the life line R. In addition, the life line R is determined in advance based on the degree of deterioration of the paint film, the degree of rusting of the base metal, and the paint film impedance Z at that time by conducting an exposure test or accelerated test of the paint film in advance. be able to. Note that, in the life estimation diagram, the time axis may be represented by the square of t, as shown in FIG. 4, in consideration of estimation accuracy.

Step S7: Prediction of degree of deterioration and repainting time The degree of deterioration is ranked based on the range of the value of the detected coating film impedance Z1. Here, it is divided into three stages A, B, and C, and a display as shown in FIG. 9 is displayed on the display 6, for example.

Step S8: Estimation of Deterioration Factors After this, when the deterioration factor estimation program is activated, expert reasoning is executed in an interactive manner, and the deterioration factors are estimated based on the measurement results of the coating film impedance Z1. , the results are displayed on the display 6. Additionally, the results and graphs that are being analyzed can be output to a printer.

As described above, in this embodiment, the CPU 12, which operates according to the above-mentioned diagnostic program, performs analysis work based on the data of the coating film impedance Z to judge the degree of deterioration of the coating film 9, and displays the judgment result on the display 16. is now displayed. As a result, it is possible to always appropriately judge the degree of deterioration of the paint film, regardless of who is performing the operation, and the work can be performed easily and accurately.

As mentioned above, when determining the degree of deterioration of the coating film 9, it is necessary to determine whether the coating impedance changes significantly over time and the logarithm of the coating impedance is linear with respect to the passage of time. In the relationship, 0.
Since the coating film impedance is measured at a frequency in the range of 0.01 Hz to 1 Hz, the degree of deterioration and remaining life of the coating film 9 can be diagnosed quantitatively, objectively, and accurately.

In the above embodiment, the judgment result is displayed on the display 6, but the present invention is not limited to this, and the judgment result may be printed out using a printer connected to the personal computer 1, for example. . Further, the present invention can be modified in various ways without departing from the scope of the invention, such as not using the general-purpose personal computer 1 but instead using a dedicated machine equipped with a display or printer.

[0054]

Effects of the Invention As is clear from the above explanation, according to the method for diagnosing paint film deterioration of the present invention, the measurement frequency of the paint film impedance is set in the range of 0.01Hz to 1Hz. This has the excellent effect of being able to quantitatively, objectively, and accurately diagnose the degree of deterioration.

[Brief explanation of the drawing]

[Fig. 1] Overall block diagram of a coating film deterioration diagnosis device showing an embodiment of the present invention.

[Figure 2] Waveform diagram showing an example of the voltage waveform applied to the coating film

[Figure 3] Paint film life estimation diagram

[Figure 4] Different display examples of paint film life estimation diagrams

[Figure 5] Flowchart of diagnostic program

[Figure 6] Characteristic diagram showing the relationship between the passage of time and coating impedance for each frequency

[Figure 7] Characteristic diagram showing the relationship between frequency and coating impedance

[Figure 8] Characteristic diagram showing the relationship between frequency and capacitive component of coating film impedance

[Figure 9] Diagram showing an example of displaying diagnostic results

[Explanation of symbols]

1 is a personal computer (judgment means), 2 is a CPU
, 6 is a display, 8 is an I/F board (voltage application means), 9 is a coating film, 10 is a probe, 11 is a base metal, 12
indicates a preamplifier (current measurement means).

Claims (1)

[Claims] 1. Voltage applying means for applying a voltage including a plurality of different frequencies between a base metal of a coating film and a probe directed to the surface of the coating film, and a current measurement device for measuring the current flowing through the coating film. and determining means for determining the degree of deterioration of the paint film based on the paint film impedance for each frequency calculated from the measurement result of the current measuring means, and the measurement frequency of the paint film impedance is 0.01 Hz.
A method for diagnosing paint film deterioration, characterized in that the frequency is set in the range of ~1Hz.