JP2020201084A - Method and device for evaluating physical characteristics - Google Patents

Abstract

To provide a method and a device for evaluating physical characteristics which can appropriately adjust the rate of a measurement.SOLUTION: The present invention relates to a method for evaluating the corrosion resistance of an electrodeposition coating film 5 as a film-like measurement target object by using an electrochemical method. The method includes the step of causing an electrolyte solution 8 to contact with a surface of the electrodeposition coating film 5. The difference between the temperature of the front side of the electrodeposition coating film 5 and the temperature of the back side of the electrodeposition coating film 5 is adjusted so that the rate of penetration of the electrolyte solution 8 into the electrodeposition coating film 5 is adjusted.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a physical property evaluation method and an apparatus thereof.

Conventionally, physical properties such as corrosion resistance of a coating film have been evaluated by using an electrochemical method (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-050915

By the way, in the field of material development, process control of a painting factory, and training of vehicle rust prevention quality, it is desired to speed up various evaluation processes using an electrochemical method. On the other hand, when elucidating the mechanism of an electrochemical reaction in more detail, it may be effective to delay the measurement speed in the electrochemical measurement step. Under these circumstances, it is desired to develop a technique capable of appropriately adjusting the measurement speed of the electrochemical measurement process according to the purpose of measurement.

An object of the present disclosure is to provide a physical property evaluation method and an apparatus thereof capable of appropriately adjusting the measurement speed.

In order to solve the above-mentioned problems, the physical property evaluation method according to the first technique disclosed herein is a method for evaluating the physical properties of a film-like object to be measured by using an electrochemical method. A step of bringing the electrolytic solution into contact with the surface of the object to be measured is provided, and by adjusting the height and difference between the temperature on the front surface side and the temperature on the back surface side of the object to be measured, the electrolytic solution is put into the object to be measured. It is characterized by adjusting the permeation rate of.

The fluid moves from a hot place with high energy to a cold place with low energy. According to this configuration, by making the temperature of the front surface side of the object to be measured in contact with the electrolytic solution higher or lower than the temperature of the back surface side, the temperature of the electrolytic solution is higher than that when the front surface side and the back surface side have the same temperature. The penetration rate into the object to be measured can be accelerated or delayed. That is, the permeation rate of the electrolytic solution into the object to be measured can be adjusted by adjusting the height and difference between the temperature on the front surface side and the temperature on the back surface side of the object to be measured. Then, the measurement speed of the electrochemical measurement step can be appropriately adjusted.

The second technique is characterized in that, in the first technique, the temperature on the front surface side of the object to be measured is made higher than the temperature on the back surface side.

According to this configuration, since the permeation speed of the electrolytic solution into the object to be measured can be accelerated, the measurement speed of the electrochemical measurement process can be increased and the electrochemical evaluation process can be speeded up.

The third technique is, in the first or second technique, a step of arranging a first temperature adjusting means for adjusting the temperature of the surface side on the surface side of the object to be measured, and a step of arranging the first temperature adjusting means for adjusting the temperature of the object to be measured. The step of arranging the second temperature adjusting means for adjusting the temperature of the back surface side on the back surface side, and the height and difference between the set temperature of the first temperature adjusting means and the set temperature of the second temperature adjusting means. It is characterized by including a step of adjusting the height and difference between the temperature on the front surface side and the temperature on the back surface side of the object to be measured by adjusting the temperature.

According to this configuration, the temperatures on the front surface side and the back surface side can be adjusted more accurately by using the first temperature adjusting means and the second temperature adjusting means. As a result, the temperature difference between the front surface side and the back surface side can be adjusted more accurately, so that the permeation rate of the electrolytic solution can be adjusted more accurately, and the measurement rate of the electrochemical measurement process can be increased. It can be adjusted accurately.

A fourth technique is the third technique, wherein the first temperature adjusting means adjusts the temperature of the electrolytic solution.

According to this configuration, the temperature on the surface side can be easily adjusted by adopting the means for adjusting the temperature of the electrolytic solution itself as the first temperature adjusting means.

A fifth technique is that in the third or fourth technique, the object to be measured is the coating film of a coated metal material having a coating film on a substrate, and the electrolytic solution is the surface of the coating film. The second temperature adjusting means is arranged on the back surface side of the coating film via the base material.

According to this configuration, the measurement speed of the electrochemical measurement step regarding the coating film of the coated metal material can be appropriately adjusted. Then, the evaluation speed of the electrochemical evaluation process of the coating film can be adjusted.

A sixth technique is that in the fifth technique, the physical property is the corrosion resistance of the coating film, and a voltage is applied between the front surface side of the coating film and the back surface side of the coating film while increasing the voltage. It is characterized in that the corrosion resistance of the coating film is evaluated based on the voltage value when the coating film undergoes dielectric breakdown.

As a method for evaluating the corrosion resistance of a coating film, for example, a voltage value when a voltage is applied between the base material of a coated metal material and the surface of the coating film to cause dielectric breakdown of the coating film (hereinafter referred to as "insulation voltage"). A method for evaluating the corrosion resistance of the coating film can be used based on the above. Since the insulation voltage indicates the quality of the insulation property related to the corrosion resistance of the coating film, the corrosion resistance of the coated metal material can be evaluated by measuring this. Then, by applying the voltage between the base material and the surface of the coating film while increasing the voltage, the insulation voltage can be detected more accurately. According to this configuration, in the process of evaluating the corrosion resistance of such a coated metal material, the measurement speed can be adjusted, and eventually the evaluation speed can be adjusted.

The seventh technique is characterized in that, in the fifth or sixth technique, the base material of the coated metal material is a steel plate for an automobile member.

According to this configuration, the evaluation speed in the evaluation process of the corrosion resistance of the coated metal material for automobiles can be adjusted.

The eighth technique is characterized in that, in any one of the fifth to seventh techniques, the coating film is an electrodeposition coating film.

According to this configuration, the measurement speed can be adjusted in the measurement regarding the corrosion resistance of the electrodeposited coating film.

A ninth technique is characterized in that, in any one of the third to eighth techniques, the first temperature adjusting means is a rubber heater and the second temperature adjusting means is a Peltier element.

According to this configuration, by adopting a rubber heater and a Peltier element as the first temperature adjusting means and the second temperature adjusting means, respectively, it is possible to more accurately adjust the temperature on the front surface side and the back surface side of the object to be measured. it can.

The physical property evaluation device according to the tenth technique disclosed herein is a device that evaluates the physical properties of a film-shaped measurement object by using an electrochemical method, and is in contact with the surface of the measurement object. The electrolytic solution arranged in the above, the electrode arranged so as to be in contact with the electrolytic solution, and the electrode and the back surface side of the measurement object are electrically connected, and the electrode and the back surface side of the measurement object are electrically connected. A power supply that applies a voltage between the two, a first temperature adjusting means that is arranged on the front surface side of the object to be measured and adjusts the temperature on the front surface side, and a first temperature adjusting means that is arranged on the back surface side of the object to be measured and the back surface. A second temperature adjusting means for adjusting the temperature on the side is provided, and the height and difference between the set temperature of the first temperature adjusting means and the set temperature of the second temperature adjusting means are adjusted to adjust the height and difference of the electrolytic solution. It is characterized in that the permeation rate into the measurement object is adjusted.

According to this configuration, by making the temperature of the front surface side of the object to be measured in contact with the electrolytic solution higher or lower than the temperature of the back surface side, the temperature of the electrolytic solution is higher than that when the front surface side and the back surface side have the same temperature. The penetration rate into the object to be measured can be accelerated or delayed. That is, the permeation rate of the electrolytic solution into the object to be measured can be adjusted by adjusting the height and difference between the set temperature of the first temperature adjusting means and the set temperature of the second temperature adjusting means. Then, the measurement speed of the electrochemical measurement step can be appropriately adjusted.

The eleventh technique is characterized in that, in the tenth technique, the set temperature of the first temperature adjusting means is higher than the set temperature of the second temperature adjusting means.

According to this configuration, since the permeation speed of the electrolytic solution into the object to be measured can be accelerated, the measurement speed of the electrochemical measurement process can be increased and the electrochemical evaluation process can be speeded up.

In the tenth or eleventh technique, the twelfth technique includes a container for accommodating the electrolytic solution, and the first temperature adjusting means is arranged on the outer periphery of the container, and the electrolytic solution is housed in the container. It is a rubber heater that adjusts the temperature of the liquid, and the second temperature adjusting means is a Peltier element arranged on the back surface side of the object to be measured.

According to this configuration, the temperature on the surface side can be easily adjusted by adopting the means for adjusting the temperature of the electrolytic solution itself as the first temperature adjusting means. Further, by adopting a rubber heater and a Peltier element as the first temperature adjusting means and the second temperature adjusting means, respectively, the temperature of the front surface side and the back surface side of the object to be measured can be adjusted more accurately.

The thirteenth technique is one of the tenth to twelfth techniques, wherein the measurement object is the coating film of a coated metal material having a coating film on a base material, and the electrolytic solution is the coating film. It is arranged so as to be in contact with the surface of the coating film, and the second temperature adjusting means is arranged on the back surface side of the coating film via the base material.

According to this configuration, the measurement speed of the electrochemical measurement step regarding the coating film of the coated metal material can be appropriately adjusted. Then, the evaluation speed of the electrochemical evaluation process of the coating film can be adjusted.

The fourteenth technique is characterized in that, in the thirteenth technique, the base material of the coated metal material is a steel plate for an automobile member.

According to this configuration, the evaluation speed in the evaluation process of the corrosion resistance of the coated metal material for automobiles can be adjusted.

The fifteenth technique is the thirteenth or fourteenth technique, wherein the coating film is an electrodeposition coating film.

According to this configuration, the measurement speed can be adjusted in the measurement regarding the corrosion resistance of the electrodeposited coating film.

The sixteenth technique is any one of the thirteenth to fourteenth techniques, wherein the physical property is the corrosion resistance of the coating film, and the power source is electrically connected to the electrode and the base material. The present invention is characterized in that a voltage is applied between the electrode and the base material while increasing the voltage, and the corrosion resistance of the coating film is evaluated based on the voltage value when the coating film undergoes dielectric breakdown.

According to this configuration, in the process of evaluating the corrosion resistance of the coated metal material, the measurement speed can be adjusted, and eventually the evaluation speed can be adjusted.

As described above, according to the present disclosure, by making the temperature of the front surface side of the object to be measured in contact with the electrolytic solution higher or lower than the temperature of the back surface side, the temperature of the front surface side and the back surface side have the same temperature. Also, the permeation rate of the electrolytic solution into the object to be measured can be accelerated or delayed. That is, the permeation rate of the electrolytic solution into the object to be measured can be adjusted by adjusting the height and difference between the temperature on the front surface side and the temperature on the back surface side of the object to be measured. Then, the measurement speed of the electrochemical measurement step can be appropriately adjusted according to the measurement purpose.

It is a figure for demonstrating the corrosion resistance evaluation apparatus and the corrosion resistance evaluation method which concerns on Embodiment 1. It is a figure which shows the change of the voltage applied between an electrode and a steel plate (dashed line), and the change of the current which flows between the electrode and the steel plate by the application of the voltage (solid line). It is a graph which shows an example of the correlation between the insulation voltage and the number of cycles of occurrence of coating film swelling. It is a figure for demonstrating the principle of the corrosion resistance evaluation method which concerns on Embodiment 1. It is a graph which shows the relationship between the temperature and the saturated water vapor amount. It is a figure for demonstrating the principle of the corrosion resistance evaluation method which concerns on Embodiment 2. It is a graph which shows the relationship between the insulation voltage and the temperature difference in an Example.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary and is not intended to limit the disclosure, its applications or its uses.

(Embodiment 1)
<Corrosion resistance evaluation device>
The corrosion resistance evaluation device 1 (physical property evaluation device) according to the present embodiment uses an electrochemical method to form an electrodeposition coating film 5 (film-like measurement object, coating film) of a coated steel sheet 2 (painted metal material). It is a device that evaluates the corrosion resistance (physical properties) of

As shown in FIG. 1, the corrosion resistance evaluation device 1 includes an electrode 6, a container 7, an electrolytic solution 8, a rubber mat 9, a power supply device 10 (power supply), an information processing terminal 11, and a rubber heater 21 (first). A temperature adjusting means) and a Peltier element 31 (second temperature adjusting means) are provided.

-Electrode-
The electrode 6 is for applying a voltage between the front surface side and the back surface side of the electrodeposition coating film 5 which is an object to be measured. Specifically, as the electrode 6, for example, a carbon electrode, a platinum electrode, or the like can be used. The shape of the electrode 6 is not particularly limited, but for example, rod-shaped, block-shaped, plate-shaped, perforated-shaped, and the like can be used. The electrodes 6 are arranged on the surface side of the electrodeposition coating film 5 at a slight distance from the surface.

-Electrolytic solution-
The electrolytic solution 8 is arranged between the surface of the electrodeposition coating film 5 and the electrode 6 so as to come into contact with both. The electrolytic solution 8 increases the conductivity between the coated steel sheet 2 and the electrode 6, and also has a role as a corrosion factor for the coated steel sheet 2. As the electrolytic solution 8, any electrolyte solution such as an aqueous solution containing a supporting electrolyte can be used. Specifically, the supporting electrolyte is, for example, sodium chloride, potassium chloride, magnesium sulfate, potassium nitrate, calcium phosphate, potassium hydrogen tartrate, or the like.

-Containers and rubber mats-
A container 7 is arranged on the surface of the electrodeposited coating film 5 of the coated steel sheet 2 via a rubber mat 9 for preventing liquid leakage. The electrolytic solution 8 is housed in the container 7. The electrode 6 is arranged in a state of being immersed in the electrolytic solution 8. Further, as described above, since the electrodes 6 are arranged slightly apart from the surface of the electrodeposition coating film 5, the electrolytic solution 8 is filled between them.

-Power supply-
The power supply device 10 is electrically connected to the electrode 6 and the steel plate 3 which is the base material of the painted steel plate 2. The power supply device 10 serves as a power supply unit that applies a voltage between the electrode 6 and the steel plate 3, and also serves as a current detection unit that detects a current flowing between the two. Specifically, as the power supply device 10, for example, a commercially available high-voltage power supply and an ammeter may be used in combination. Further, a controllable potentiometer / galvanostat or the like may be used as the voltage / current application method.

-Information processing terminal-
The information processing terminal 11 is communicably connected to the power supply device 10. The information processing terminal 11 has a role as a control unit that controls the voltage applied between the electrode 6 and the steel plate 3 by the power supply device 10. Further, the power supply device 10 has a role as a determination unit for evaluating the corrosion resistance of the coated steel sheet 2 based on the voltage value when the electrodeposition coating film 5 undergoes dielectric breakdown due to the application of a voltage by the power supply device 10. As the information processing terminal 11, specifically, for example, a general-purpose computer provided with a display, a keyboard, or the like can be used.

-Rubber heater-
The rubber heater 21 is arranged on the outer periphery of the container 7 and is a temperature adjusting means for adjusting the temperature of the electrolytic solution 8 housed in the container 7. The rubber heater 21 is not particularly limited, and a commercially available rubber heater 21 can be adopted. By adopting the rubber heater 21 as the first temperature adjusting means, the temperature of the electrolytic solution 8 can be adjusted accurately and easily, and by extension, the temperature on the surface side of the electrodeposited coating film 5 can be adjusted accurately and easily. Can be done. The rubber heater 21 is fixed so as to come into contact with the outer peripheral surface of the container 7 using, for example, double-sided tape, fasteners, or the like. A temperature sensor and a temperature controller (not shown) are electrically connected to the rubber heater 21. The temperature sensor is immersed in the electrolytic solution 8 in the container 7. Then, the temperature of the rubber heater 21 is controlled by the temperature controller to adjust the temperature of the electrolytic solution 8.

-Peltier element-
The Peltier element 31 is arranged on the back surface side of the electrodeposition coating film 5 via the steel plate 3 and the chemical conversion film 4. Specifically, the Peltier element 31 is arranged so as to be in contact with the back surface of the steel plate 3, and the temperature of the back surface side of the electrodeposition coating film 5 is adjusted by adjusting the temperature of the steel plate 3. The Peltier element 31 is not particularly limited, and a commercially available one can be adopted. By adopting the Peltier element 31, the temperature of the steel sheet 3 can be adjusted accurately and easily, and by extension, the temperature of the back surface side of the electrodeposition coating film 5 can be adjusted accurately and easily. A temperature controller (not shown) is electrically connected to the Peltier element 31. The temperature of the Peltier element 31 is controlled by the temperature controller to adjust the temperature of the steel plate 3.

<Corrosion resistance evaluation method>
The corrosion resistance evaluation method (physical property evaluation method) according to the present embodiment is a method of evaluating the corrosion resistance of the electrodeposited coating film 5 by using an electrochemical method, and can be performed using, for example, the above-mentioned corrosion resistance evaluation device 1. it can. The corrosion resistance evaluation method according to the present embodiment includes a preparation step, a temperature adjustment step, a measurement step, and an evaluation step. Hereinafter, it will be described in detail with reference to FIGS. 1 to 4.

≪Preparation process≫
-Preparation of test piece-
First, a test piece of the coated steel sheet 2 (painted metal material) as an evaluation target is prepared. In the present embodiment, the coated steel sheet 2 includes a steel sheet 3 as a base material, a chemical conversion film 4 formed on the surface of the steel sheet 3, and an electrodeposition coating film 5 as a coating film formed on the steel sheet 3 (measurement). It is composed of an object). That is, the steel plate 3 is arranged on the back surface side of the electrodeposition coating film 5.

The steel plate 3 is a steel plate for manufacturing home appliances, building materials, automobile parts, and the like, and more preferably a steel plate for automobile members. Specifically, for example, a cold-rolled steel sheet (SPC), an alloyed hot-dip galvanized steel sheet (GA), a high-strength steel sheet, a hot stamping material, or the like can be used, and more preferably SPC or GA.

The chemical conversion film 4 has a role of suppressing direct contact of the corrosive factor with the steel sheet 3 and suppressing rust by making the surface of the steel sheet 3 an alkaline environment by reacting with the chemical conversion film 4 itself. It also has a role of improving the adhesion between the electrodeposition coating film 5 and the steel plate 3. Specifically, for example, a chromate chemical conversion film, a zinc phosphate film, or the like.

The electrodeposition coating film 5, which is the object to be measured, has a role of protecting the steel sheet 3 by having high turning properties and uniformity, and exhibiting high corrosion resistance after the baking step. Specifically, for example, an epoxy resin-based paint, an acrylic resin-based paint, or the like can be used.

-Preparation for measurement-
After preparing the test piece of the coated steel sheet 2, the measurement of the corrosion resistance evaluation device 1 is prepared.

Specifically, for example, first, the container 7 is installed on the surface of the electrodeposited coating film 5 of the coated steel sheet 2 via the rubber mat 9. A rubber heater 21 is arranged around the container 7. Further, the Peltier element 31 is arranged so as to come into contact with the back surface of the steel plate 3 of the painted steel plate 2. Further, the wiring to which the electrode 6 of the power supply device 10 is not connected is connected to the steel plate 3 of the painted steel plate 2.

Next, the electrolytic solution 8 is filled in the container 7. As a result, the electrolytic solution 8 is brought into contact with the surface of the electrodeposition coating film 5. Then, the electrode 6 connected to the power supply device 10 is immersed in the electrolytic solution 8 and held above the surface of the electrodeposition coating film 5 in a non-contact state. Further, the temperature sensor connected to the rubber heater 21 is also immersed in the electrolytic solution 8.

≪Temperature adjustment process≫
In this state, the difference between the set temperature of the rubber heater 21 and the set temperature of the Peltier element 31 is adjusted. Then, the difference between the temperature on the front surface side and the temperature on the back surface side of the electrodeposited coating film 5 is adjusted. The details of the temperature adjustment will be described later.

≪Measurement process≫
Under the control of the information processing terminal 11, a voltage is applied between the electrode 6 and the steel plate 3 by the power supply device 10. At this time, as shown by the alternate long and short dash line in FIG. 2, the voltage applied by the power supply device 10 is applied while gradually increasing, that is, gradually increasing with time. Thereby, the insulation voltage can be detected more accurately. Specifically, the sweep rate of the applied voltage is, for example, in the range of 0.1 to 10 V / s, more preferably 0.5 to 2 V / s.

Then, the power supply device 10 detects the current flowing between the electrode 6 and the steel plate 3 when a voltage is applied. In FIG. 2, the change in current is shown by a solid line. As shown in FIG. 2, the current between them, even by increasing the applied voltage, hardly flows until the voltage value V ₁ to the time t _1. However, when the voltage value V ₁ is exceeded, the amount of current rapidly increases, and the amount of current reaches the threshold value A1 at the voltage value V ₂ (time t ₂ ).

This can be thought of as follows. That is, the corrosion factor in the electrodeposited coating film 5, that is, the breaking performance of the electrolytic solution 8 is maintained until the voltage value V ₁ , and the amount of current is suppressed. On the other hand, the increase in the applied voltage promotes the penetration of the electrolytic solution 8 into the electrodeposition coating film 5 into the electrodeposition coating film 5. Then, as shown by reference numeral 12 in FIG. 1, the electrodeposition coating film 5 is gradually destroyed by the permeation of the electrolytic solution 8, and the electrolytic solution 8 eventually reaches the surface of the steel sheet 3. As a result, it is considered that the conductivity between the electrode 6 and the steel plate 3 increased sharply, and the amount of current increased sharply. That is, it can be considered that when the electrolytic solution 8 reaches the surface of the steel sheet 3, the electrodeposition coating film 5 is dielectrically broken down and its blocking performance is lost.

≪Evaluation process≫
Assuming that the voltage value V ₂ when the amount of current reaches the threshold value A ₁ is the insulation voltage, it is considered that the time t _{2 at} which the insulation voltage V ₂ is reached corresponds to the period until the corrosion factor reaches the steel sheet 3.

Generally, in a coated metal material, a corrosion factor such as salt water permeates the coating film and reaches the base material to cause rust, that is, corrosion to start. Therefore, the corrosion process of the coated metal material is divided into a process until rust is generated and a process in which the generated rust develops, and the period until corrosion starts (corrosion suppression period) and the rate at which corrosion progresses (corrosion suppression period), respectively. It can be evaluated by determining (corrosion rate). Time t ₂ as the insulating voltage V _2, since the corrosion factor corresponds to a period until the steel plate 3, the insulating voltage V ₂ shows the insulating quality of the corrosion resistance of the coating film, the corrosion There is a correlation with the suppression period.

The corrosion suppression period can be separately experimentally measured by a corrosion acceleration test such as a composite cycle test or a salt spray test. Therefore, the correlation between the corrosion suppression period and the insulation voltage is experimentally obtained in advance, and based on this correlation, the corrosion suppression period of the test piece is obtained from the measured value of the insulation voltage of the test piece. The corrosion resistance of the film can be evaluated.

Specifically, obtained by the combined cycle test is accelerated corrosion test shows the number of coating blistering generation cycles illustrating the corrosion inhibiting period, an example of the correlation between the insulation voltage V ₂ in Figure 3. The evaluation target is to form a zinc phosphate film as the chemical conversion film 4 on the surface of the SPC as the steel sheet 3, and further to form an electrodeposition coating film with an epoxy resin-based paint as the electrodeposition coating film 5 on the surface. It is a coated steel plate 2 in which. In the composite cycle test, each step of spraying salt water (8 hours), drying (8 hours), and wetting (8 hours) is performed on the test piece as one cycle for 24 hours, and the coating film swells on 20% of the surface of the test piece. This was performed by determining the number of cycles in which (rust) was formed, that is, the number of cycles in which coating film swelling occurred, as the corrosion suppression period. The insulation voltage was measured by the above method in an environment where the outside air temperature was 23 ° C. and the outside air humidity was 30%, and the set temperatures of the rubber heater 21 and the Peltier element 31 were both set to 23 ° C.

In FIG. 3, the four points shown in S1 to S4 indicate the coated steel sheets 2 having the film thicknesses of the electrodeposition coating film 5 of 5 μm, 7 μm, 10 μm, and 15 μm, respectively, under baking conditions of 150 ° C. for 20 minutes. Further, at the three points S5, S6, and S3, the baking conditions of the coated steel sheet 2 having a film thickness of 10 μm of the electrodeposition coating film 5 were 140 ° C. for 15 minutes, 140 ° C. for 20 minutes, and 150 ° C. for 20 minutes, respectively. Is shown. As shown in FIG. 3, the above points are along the regression line even if the film thickness and the baking conditions of the electrodeposited coating film 5 change, and the coefficient of determination R2 is 0.83. It can be said that there is a high correlation between the number of coating film swelling occurrence cycles as the suppression period and the insulation voltage V ₂ .

As described above, as the corrosion resistance of the electrodeposition coating film 5, the corrosion suppression period of the test piece is obtained from the measured value of the insulation voltage V ₂ of the test piece based on the above correlation, and the corrosion resistance of the electrodeposition coating film 5 is determined. Can be evaluated.

The current amount threshold value A ₁ may be set to such that a sudden increase in the current amount can be detected, and specifically, for example, it is preferably 0.5 mA or more. Further, it is more preferably 1 to 50 mA, and particularly preferably 5 to 15 mA.

<Features>
In the corrosion resistance evaluation method according to the present embodiment, the temperature on the front surface side and the temperature on the back surface side of the electrodeposition coating film 5 are adjusted by adjusting the height and difference between the set temperature of the rubber heater 21 and the set temperature of the Peltier element 31. It is characterized by adjusting the height and difference of. Hereinafter, the temperature adjustment step will be described in detail.

As described above, the electrolytic solution 8 arranged so as to come into contact with the surface of the electrodeposition coating film 5 permeates into the inside of the electrodeposition coating film 5 from the surface side.

At this time, for example, if the set temperature of the rubber heater 21 is higher than the set temperature of the Peltier element 31, the temperature of the electrolytic solution 8 becomes higher than the temperature of the steel plate 3. Then, the temperature on the front surface side of the electrodeposition coating film 5 in contact with the electrolytic solution 8 becomes higher than the temperature on the back surface side of the electrodeposition coating film 5 in contact with the steel sheet 3. As a result, a temperature gradient is generated in the electrodeposited coating film 5 so that the temperature decreases from the front surface side to the back surface side.

Here, the fluid moves from a hot place with high energy to a cold place with low energy. Therefore, when the temperature gradient is generated inside the electrodeposition coating film 5 as described above, as shown by the arrow in FIG. 4, the electrodeposition coating film 5 of the electrolytic solution 8 is compared with the case where the temperature gradient is not generated. The rate of penetration into the interior is accelerated. As a result, the time t ₂ until the insulation voltage V ₂ shown in FIG. 2 is shortened, so that the measurement speed of the insulation voltage V ₂ can be improved and the corrosion resistance evaluation process can be speeded up.

On the contrary, when the set temperature of the rubber heater 21 is lower than the set temperature of the Peltier element 31, the temperature of the electrolytic solution 8 becomes lower than the temperature of the steel plate 3. Then, a temperature gradient is generated inside the electrodeposition coating film 5 so that the temperature increases from the front surface side to the back surface side. As a result, the permeation rate of the electrolytic solution 8 inside the electrodeposition coating film 5 can be reduced as compared with the case where the temperature gradient does not occur. For example, when comparing the corrosion resistance of a plurality of electrodeposited coating films 5, the permeation rate of the electrolytic solution 8 is too high in the first place due to the film quality of the electrodeposited coating film 5, and it is difficult to observe the difference between these measurement objects. In some cases. In such a case, it may be effective to reduce the penetration rate of the electrolytic solution 8 into the electrodeposition coating film 5.

Regardless of which of the set temperature of the rubber heater 21 and the set temperature of the Peltier element 31 is high, the degree of acceleration or decrease of the permeation rate can be increased by increasing the difference between the two.

By adjusting the height and difference between the temperature on the front surface side and the temperature on the back surface side of the electrodeposition coating film 5 in this way, the penetration rate of the electrolytic solution into the electrodeposition coating film 5 can be adjusted. As a result, the time t ₂ until the insulation voltage V ₂ is reached can be shortened. Then, the measurement speed of the measurement step in the corrosion resistance evaluation method can be appropriately adjusted.

(Embodiment 2)
Hereinafter, other embodiments according to the present disclosure will be described in detail. In the description of these embodiments, the same parts as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the above-mentioned temperature adjustment step, the corrosion resistance evaluation method and the evaluation device according to the present embodiment set the temperature of the rubber heater 21 higher than the temperature at which the water vapor in the electrodeposition coating film 5 starts to condense, and the Peltier element. The set temperature of 31 is set to be lower than the temperature at which the water vapor in the electrodeposited coating film 5 begins to condense.

Generally, the saturated water vapor amount a (T) [g / m ³ ] contained in the atmosphere is the mass (g) of water vapor that can exist in the space per unit volume (1 m ³ ), and is calculated by the following formula (1). Will be done.

a (T) = (217 × e (T)) / (T + 273.15) ・ ・ ・ (1)
However, T is the temperature [° C.] and e (T) is the saturated water vapor pressure [hPa]. e (T) can be approximately obtained by the following equation (2).

e (T) = 6.1078 × 10 ^ [7.5T / (T + 237.3)] ・ ・ ・ (2)
The relationship between the saturated water vapor amount calculated by the above formula (1) and the temperature is shown in FIG. For example, consider an environment in which the outside air temperature is 25 ° C. and the outside air humidity is 30%. At this time, the amount of saturated water vapor contained in the outside air is about 23 g. Then, since the outside air humidity is 30%, about 7 g (= 23 g × 0.3) of water vapor is contained in the outside air. Then, when the outside air temperature is lowered to, for example, 0 ° C., as shown in FIG. 5, since the amount of saturated water vapor at a temperature of 0 ° C. is about 5 g, about 2 g (= 7-5) of water vapor is condensed into liquid water. ..

The set temperature of the rubber heater 21, that is, the temperature of the electrolytic solution 8 is set higher than the temperature at which the water vapor in the electrodeposition coating film 5 starts to condense, and the set temperature of the Peltier element 31, that is, the temperature of the steel plate 3 is set to the water vapor of the outside air. Lower than the temperature at which water vapor begins to condense. Then, the water vapor contained in the air existing on the front surface side of the electrodeposition coating film 5 is condensed and liquefied on the back surface side of the electrodeposition coating film 5. Then, in addition to the temperature gradient, a flow of water vapor and liquid water as shown by the arrow in FIG. 6 is formed in the electrodeposition coating film 5. As a result, the penetration of the electrolytic solution 8 is greatly promoted.

In particular, when the set temperature of the rubber heater 21 is higher than the outside air temperature, the amount of water vapor contained in the air existing on the surface side of the electrodeposition coating film 5 can be increased, so that the surface side in the electrodeposition coating film 5 can be increased. It is possible to increase the flow of water vapor and liquid water from the surface to the back surface side. As a result, the penetration of the electrolytic solution 8 into the electrodeposition coating film 5 can be further promoted.

Even when the set temperature of the Peltier element 31, that is, the temperature of the steel plate 3 is lowered to 0 ° C. or lower, the liquefied water is liquefied at a temperature higher than the temperature at which the liquefied water actually starts to solidify. The water is supercooled and does not solidify. Then, when the set temperature of the Peltier element 31 is lowered to a temperature below the temperature at which the liquefied water begins to solidify, the liquefied water begins to solidify. When the liquefied water solidifies, it is considered difficult to promote the penetration of the electrolytic solution 8 into the electrodeposition coating film 5. Therefore, the set temperature of the Peltier element 31, that is, the temperature of the steel plate 3, can be set to be higher than the temperature at which the liquefied water begins to solidify. The temperature at which the liquefied water begins to solidify can change depending on various conditions such as measurement conditions.

As described above, according to the corrosion resistance evaluation method and the evaluation device according to the present embodiment, the permeation rate of the electrolytic solution 8 into the electrodeposition coating film 5 can be significantly accelerated. As a result, the measurement speed of the electrochemical measurement process can be improved, and the evaluation process using the electrochemical method can be speeded up.

(Other embodiments)
In the above embodiment, the first temperature adjusting means is a rubber heater and the second temperature adjusting means is a Peltier element, but the means for adjusting the temperature difference between the front surface side and the back surface side of the electrodeposited coating film 5 is the same configuration. Not limited to. For example, either one of the first temperature adjusting means and the second temperature adjusting means may be provided to raise or lower the temperature of either the front surface side or the back surface side of the electrodeposited coating film 5. Further, both the first temperature adjusting means and the second temperature adjusting means may be a rubber heater or a Peltier element. Further, the first temperature adjusting means may be a Peltier element and the second temperature adjusting means may be a rubber heater. As the heating device, a hot plate or the like may be used instead of the rubber heater. Further, in the first temperature adjusting means, instead of the electrolytic solution 8, a rubber heater or a Peltier element is arranged on the surface of the electrodeposition coating film 5 on the outside of the container 7 to heat the surface side of the electrodeposition coating film 5 itself. Alternatively, it may be cooled.

In the above embodiment, in the measurement step, the voltage is applied while gradually increasing with time, and the detected insulation voltage V ₂ is configured, but the measurement method is not limited to this configuration. Specifically, for example, a change in the amount of current is observed while a constant voltage is applied, and the corrosion resistance of the electrodeposited coating film 5 is evaluated based on the time t ₂ from the start of measurement until the amount of current reaches the threshold value A _1. You may adopt the method of doing.

In the above embodiment, the coated steel sheet 2 to be evaluated can be configured to include two or more multilayer films as a coating film. Specifically, for example, in addition to the electrodeposition coating film 5, an intermediate coating film is provided on the surface of the electrodeposition coating film 5, or an intermediate coating film or the like is further provided on the intermediate coating film. It can be a multilayer film. The intermediate coating film has a role of ensuring the finish and chipping resistance of the coated steel sheet 2 and improving the adhesion between the undercoat coating film and the topcoat coating film. Further, the topcoat coating film ensures the color, finish and weather resistance of the coated steel sheet 2. Specifically, these coatings are paints composed of a base resin such as polyester resin, acrylic resin, and alkyd resin, and a cross-linking agent such as melamine resin, urea resin, and polyisocyanate compound (including a block). Is formed by. With this configuration, for example, in a manufacturing process of an automobile member, parts can be taken out from the manufacturing line in each painting process, and the quality of the coating film can be confirmed.

In the above embodiment, a conductive solid material containing an electrolytic solution 8 may be used instead of the container 7 and the rubber mat 9. The conductive solid material may be a solid material that contains the electrolytic solution 8 and can take an arbitrary shape according to the shape to be evaluated, and has conductivity. Specifically, for example, a solid material containing oils such as sodium chloride, potassium hydrogen tartrate, distilled water and oleic acid, linoleic acid, etc. is preferable with respect to the solid material raw material powder composed of gliadin, glutenin, starch and the like. At this time, the blending ratio of each component was as follows: solid raw material powder 30 to 50%, sodium chloride 10 to 30%, potassium hydrogen tartrate 10 to 30%, distilled water 10 to 45%, oil content 3 to 15 in volume ratio. It is preferably%. With this configuration, it is possible to perform measurement on a test piece having no flat surface, specifically, for example, on an edge portion of a coated steel plate 2, a curved surface, or the like, without restricting the shape of the test piece. .. When a conductive solid material is used, as described above, a first temperature adjusting means such as a rubber heater and a Peltier element is arranged on the surface of the electrodeposition coating film 5, and the surface side itself of the electrodeposition coating film 5 is formed. It is effective to heat or cool.

The above-described embodiment has been described by exemplifying the corrosion resistance evaluation method and the corrosion resistance evaluation method of the electrodeposited coating film 5 of the coated steel sheet 2 as the physical property evaluation method and the physical property evaluation device according to the present disclosure, but the present invention is limited to this. Absent. That is, the physical property evaluation method and the physical property evaluation device according to the present disclosure can be widely used for the physical property evaluation of a film-shaped measurement object using an electrochemical method. Specifically, for example, it can be used for evaluation of redox characteristics by cyclic voltammetry measurement of a film-like object to be measured.

Hereinafter, specific examples will be described.

<Test piece>
In Examples 1 to 5, the configurations of the test pieces were the same.

Specifically, SPC was used as the steel sheet 3, and a test piece (about 50 mm square) of the coated steel sheet 2 having the chemical conversion film 4 and the electrodeposition coating film 5 formed on the surface thereof was prepared. The chemical conversion film 4 was a zinc phosphate film, and the chemical conversion treatment time with zinc phosphate was 120 seconds. The electrodeposition coating film 5 was formed by using an epoxy resin-based paint. The baking condition of the electrodeposition coating was 150 ° C. × 20 minutes. The thickness of the steel plate 3 was 2 mm, and the thickness of the electrodeposition coating film 5 was 10 μm.

<Corrosion resistance evaluation test>
Using the above test piece, the corrosion resistance of the electrodeposition coating film 5 was evaluated using the corrosion resistance evaluation device 1 of FIG.

Specifically, an acrylic resin cylinder having an inner diameter of 20 mm, an outer diameter of 22 mm, and a height of 60 mm was used as the container 7. A silicon rubber heater (manufactured by Hakkou Denki Co., Ltd., standard type, A type with double-sided tape) as a rubber heater 21 was attached over the entire circumference and height of the outer peripheral surface of the container 7. A temperature sensor (manufactured by Three High Co., Ltd., thermocouple (K type) mold type) is connected to the rubber heater 21, and the sensor portion at the tip of the temperature sensor is immersed in the electrolytic solution 8. As the rubber mat 9, a commercially available silicon rubber sheet (thickness: about 0.5 mm, 30 mm × 30 mm) having a hole having a diameter of 18 mm was used. The rubber mat 9 was placed on the surface of the electrodeposition coating film 5, and the container 7 to which the rubber heater 21 was attached was arranged so as to cover the holes of the rubber mat 9. The container 7 was filled with a 5% by mass sodium chloride aqueous solution as the electrolytic solution 8. As the electrode 6, a commercially available rod-shaped carbon electrode (diameter: about 5 mm, length: about 30 mm) was immersed in the electrolytic solution 8. A thermo module (LVPU-70 manufactured by Bix Co., Ltd.) was arranged as a Peltier element 31 on the back surface side of the steel plate 3. A high-voltage power supply (Made by Trek Japan Co., Ltd., Model 2220) and an ammeter (Kikusui Electronics Co., Ltd., DME1600) were connected to the electrode 6 and the steel plate 3 as a power supply device 10. A temperature controller (manufactured by Yakko Denki Co., Ltd., Double Thermo 100) was connected to the rubber heater 21 to control the temperature. Further, a temperature controller (manufactured by Bix Co., Ltd., VTH-1000) was connected to the Peltier element 31 to control the temperature. The set temperatures of the rubber heater 21 and the Peltier element 31 are as shown in Table 1.

For the test pieces of Examples 1 to 5, the voltage value of the electrode 6 with respect to the steel plate 3 was increased at a sweep rate of 0 V to 1 V / s using the above high-voltage power supply in an environment of an outside air temperature of 25 ° C. and an outside air humidity of 30%. The insulation voltage V ₂ was measured. The results are shown in FIG.

As described above, the time t ₂ as the insulating voltage V _2, the corrosion factor corresponds to the time to reach the steel plate 3. Then, even for the same object to be measured, as the permeation rate of the electrolytic solution 8 increases, the time t ₂ becomes shorter and the insulation voltage V ₂ becomes smaller. On the contrary, when the permeation rate of the electrolytic solution 8 becomes slow, the time t ₂ becomes long and the insulation voltage V ₂ becomes large. That is, for the same measurement object, the insulation voltage V ₂ decreases as the permeation rate of the electrolytic solution 8 increases.

From the results of Examples 1 to 4, as shown by the regression line L1 in FIG. 7, the temperature difference between the rubber heater 21 and the Peltier element 31 in a state where the set temperature of the rubber heater 21 is higher than the set temperature of the Peltier element 31. It was found that when the temperature increases, the insulation voltage V ₂ decreases, that is, the permeation rate of the electrolytic solution 8 increases.

Further, from the results of Example 5, when the temperature of the Peltier element 31 is lowered to −0.5 ° C., which is lower than the temperature at which water vapor in the atmosphere begins to condense (about 7 ° C. in this test environment), FIG. As shown by the arrow P1, it was found that the insulation voltage deviates from the regression line L1 of the results of Examples 1 to 4 and drops significantly. When the temperature of the Peltier element 31 is lowered to −0.5 ° C., water vapor in the atmosphere is condensed near the interface between the steel sheet 3 and the electrodeposition coating film 5, and the electrolytic solution 8 permeates into the electrodeposition coating film 5. Is considered to have been greatly promoted. By increasing the temperature difference from the rubber heater 21 in a state where the temperature of the Peltier element 31 is lower than the temperature at which water vapor in the atmosphere begins to condense, the insulation voltage is lowered as shown by the straight line L2 in FIG. That is, it is considered that an increase in the permeation rate of the electrolytic solution 8 is observed.

The present disclosure is useful in the field of physical property evaluation methods and devices thereof.

1 Corrosion resistance evaluation device 2 Painted steel plate (painted metal material)
3 Steel plate (base material)
4 Chemical conversion film (base material)
5 Electrodeposition coating film (measurement target)
6 Electrode 8 Electrolyte 10 Power supply (power supply)
21 Rubber heater (first temperature adjusting means)
31 Peltier element (second temperature adjusting means)
V ₂ insulation voltage (voltage value when the coating film breaks down)

Claims (16)

A method of evaluating the physical properties of a film-like object to be measured using an electrochemical method.
A step of bringing the electrolytic solution into contact with the surface of the object to be measured is provided.
A method for evaluating physical properties, which comprises adjusting the permeation rate of the electrolytic solution into the object to be measured by adjusting the height and difference between the temperature on the front surface side and the temperature on the back surface side of the object to be measured. .. In claim 1,
A method for evaluating physical properties, characterized in that the temperature on the front surface side of the object to be measured is made higher than the temperature on the back surface side. In claim 1 or 2,
A step of arranging a first temperature adjusting means for adjusting the temperature of the surface side on the surface side of the measurement object, and
A step of arranging a second temperature adjusting means for adjusting the temperature of the back surface side on the back surface side of the measurement object, and
By adjusting the height and difference between the set temperature of the first temperature adjusting means and the set temperature of the second temperature adjusting means, the height and difference between the temperature on the front surface side and the temperature on the back surface side of the object to be measured can be adjusted. A physical property evaluation method characterized by having a step of adjusting. In claim 3,
The first temperature adjusting means is a method for evaluating physical properties, which comprises adjusting the temperature of the electrolytic solution. In claim 3 or 4,
The object to be measured is the coating film of a coated metal material having a coating film on a base material.
The electrolytic solution is arranged so as to be in contact with the surface of the coating film.
A method for evaluating physical properties, wherein the second temperature adjusting means is arranged on the back surface side of the coating film via the base material. In claim 5,
The physical property is the corrosion resistance of the coating film.
Applying a voltage between the front surface side of the coating film and the back surface side of the coating film while increasing the voltage, and evaluating the corrosion resistance of the coating film based on the voltage value when the coating film undergoes dielectric breakdown. Characteristic physical property evaluation method. In claim 5 or 6,
A method for evaluating physical properties, wherein the base material of the coated metal material is a steel plate for an automobile member. In any one of claims 5 to 7,
A method for evaluating physical properties, wherein the coating film is an electrodeposition coating film. In any one of claims 3 to 8,
The first temperature adjusting means is a rubber heater.
A method for evaluating physical properties, wherein the second temperature adjusting means is a Peltier element. A device that evaluates the physical properties of a film-like object to be measured using an electrochemical method.
An electrolytic solution arranged so as to come into contact with the surface of the object to be measured,
An electrode arranged to be in contact with the electrolytic solution and
A power source that is electrically connected to the electrode and the back surface side of the measurement object and applies a voltage between the electrode and the back surface side of the measurement object.
A first temperature adjusting means arranged on the surface side of the object to be measured and adjusting the temperature on the surface side,
A second temperature adjusting means, which is arranged on the back surface side of the object to be measured and adjusts the temperature on the back surface side, is provided.
By adjusting the height and difference between the set temperature of the first temperature adjusting means and the set temperature of the second temperature adjusting means, the permeation rate of the electrolytic solution into the measurement object is adjusted. Physical property evaluation device. In claim 10,
A physical property evaluation device characterized in that the set temperature of the first temperature adjusting means is higher than the set temperature of the second temperature adjusting means. In claim 10 or 11.
A container for accommodating the electrolytic solution is provided.
The first temperature adjusting means is a rubber heater arranged on the outer periphery of the container and adjusting the temperature of the electrolytic solution contained in the container.
The second temperature adjusting means is a physical property evaluation device characterized by being a Peltier element arranged on the back surface side of the object to be measured. In any one of claims 10 to 12,
The object to be measured is the coating film of a coated metal material having a coating film on a base material.
The electrolytic solution is arranged so as to be in contact with the surface of the coating film.
The second temperature adjusting means is a physical property evaluation device characterized in that it is arranged on the back surface side of the coating film via the base material. In claim 13,
A physical property evaluation device characterized in that the base material of the coated metal material is a steel plate for an automobile member. In claim 13 or 14,
A physical property evaluation device characterized in that the coating film is an electrodeposition coating film. In any one of claims 13 to 14,
The physical property is the corrosion resistance of the coating film.
The power source is electrically connected to the electrode and the base material.
A physical property evaluation apparatus characterized in that a voltage is applied between the electrode and the base material while increasing the voltage, and the corrosion resistance of the coating film is evaluated based on the voltage value when the coating film undergoes dielectric breakdown. ..

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