JP2009014470A - Corrosion resistance evaluation method and corrosion resistance evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for evaluating simply and quickly corrosion resistance of a coating provided on the surface of a metal material. <P>SOLUTION: This evaluation method of the corrosion resistance of the coating provided on the surface of the metal material has characteristics wherein a metal material evaluation object having a surface constituted of a coating part and an exposure part having an exposed base metal is held in a corrosion resistance evaluation liquid so that only a part of the coating part and the exposure part is dipped thereinto in an atmosphere containing oxygen, and a surface having the coating part and the exposure part dipped into the corrosion resistance evaluation liquid is observed as a corrosion resistance evaluation part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a corrosion resistance evaluation method and a corrosion resistance evaluation apparatus, and more particularly to a method and apparatus for evaluating the corrosion resistance of a surface coating provided on a metal material surface such as a plating coating or a coating.

  A so-called floating caliper disc brake device is known as a vehicle disc brake device. A brake device of this type usually includes a disk-shaped rotor that rotates integrally with a wheel, a pair of friction pads that are arranged to face each other, and a piston that presses the friction pad against the rotor. It has a built-in caliper body and a support that is attached to the vehicle body side and supports the caliper body so as to be slidable in the axial direction of the rotor.

  The caliper body is equipped with a bridge portion over the rotor, a cylinder portion that is equipped on one end side of the bridge portion and accommodates the piston so as to advance and retreat, and is equipped on the other end side of the bridge portion. It has a caliper claw for pressing the back surface of the other friction pad.

  The caliper body and support constituting the disk brake device are usually made of spheroidal graphite cast iron (a material equivalent to FCD450), and the surface thereof is subjected to chromate treatment with galvanizing and trivalent chromium to ensure corrosion resistance.

  As a method for evaluating the corrosion resistance of a coating provided on the surface of an iron-based material such as a plating film or coating on the surface, a method described in Non-Patent Document 1 is known.

  The method described in Non-Patent Document 1 is to form a scratch of a predetermined shape on the coating on the surface of the test piece, and to evaluate the corrosion resistance after spraying a predetermined concentration of salt water for a predetermined time. As the shape of the scratch For example, there are known ones in which straight scratches are crossed (cross cut).

The method described in Non-Patent Document 1 promotes corrosion of the base metal by forming scratches such as crosscuts on the surface, but the measurement time is as long as 240 hours, for example. Therefore, there is a problem that it is not suitable as a simple and quick evaluation method.
JIS Handbook 2000, Steel I, pp. 238-244, “Salt spray test method Z 2371”, edited by Japanese Standards Association

  Under such circumstances, a first object of the present invention is to provide a method for simply and quickly evaluating the corrosion resistance of a coating provided on the surface of a metal material. A second object of the present invention is to provide a corrosion resistance evaluation apparatus that can perform such a process.

  As a result of intensive studies in order to achieve the above object, the present inventors, as a result, a metal material evaluation product whose surface is constituted by a coating part and an exposed part where a bare metal is exposed, in an oxygen-containing atmosphere, The above first method is based on the method of observing the surface having the coating part and the exposed part immersed in the corrosion resistance evaluation liquid as the corrosion resistance evaluation part so that only a part of each of the coating part and the exposed part is immersed. It was found that the purpose of can be achieved. In addition, a container that can contain a metal material evaluation product and a corrosion resistance evaluation liquid whose surface is constituted by a coating portion and an exposed portion from which the metal is exposed, and a coating portion and an exposed portion of the metal material evaluation product, respectively. A holder capable of adjusting the position and angle of the metal material evaluation product so that only the part can be immersed in the corrosion resistance evaluation liquid, an observation means for observing the immersed part as the corrosion resistance evaluation part, and the observation means electrically It has been found that the second object can be achieved by an apparatus including measuring means to be connected. The present invention has been completed based on these findings.

That is, the present invention
(1) A method for evaluating the corrosion resistance of a coating provided on the surface of a metal material,
A metal material evaluation product whose surface is composed of a coating part and an exposed part where the bare metal is exposed,
In an oxygen-containing atmosphere, hold in the corrosion resistance evaluation solution so that only a part of each of the coating part and the exposed part is immersed,
A method for evaluating corrosion resistance, comprising observing a surface having a coating portion and an exposed portion immersed in the corrosion resistance evaluation solution as a corrosion resistance evaluation portion.
(2) The corrosion resistance evaluation method according to the above (1), wherein the coating film is formed by plating or painting.
(3) The corrosion resistance evaluation method according to (1) or (2), wherein the oxygen-containing atmosphere is an air atmosphere,
(4) The corrosion resistance evaluation method according to any one of (1) to (3), wherein the corrosion resistance evaluation solution is a sodium chloride-containing aqueous solution.
(5) The corrosion resistance evaluation method according to any one of the above (1) to (4), wherein the corrosion resistance evaluation section is planar and is subjected to surface polishing.
(6) Any of the above (1) to (5), in which the metal material evaluation product is immersed and held in a corrosion resistance evaluation solution in a state where the surface having the coating portion and the exposed portion is embedded in the resin The corrosion resistance evaluation method according to crab,
(7) Any of the above (1) to (6) that evaluates the corrosion resistance based on the ratio of the area of the portion where red rust is generated or the area of the portion where no red rust is generated to the area of the corrosion resistance evaluation portion And (8) an apparatus for evaluating the corrosion resistance of a coating provided on the surface of a metal material,
A container capable of containing a metal material evaluation product and a corrosion resistance evaluation liquid, the surface of which is constituted by a coating portion and an exposed portion from which the metal is exposed;
A holder that can adjust the position and angle of the metal material evaluation product so that only a part of the coating portion and the exposed portion of the metal material evaluation product can be immersed in the corrosion resistance evaluation solution;
Observation means for observing the immersed part as a corrosion resistance evaluation part,
A corrosion resistance evaluation apparatus comprising a measurement means electrically connected to the observation means;
Is to provide.

  According to the present invention, the metal material evaluation product, the surface of which is constituted by the coating portion and the exposed portion where the bare metal is exposed, is immersed in each part of the coating portion and the exposed portion in an oxygen-containing atmosphere. By maintaining in the corrosion resistance evaluation liquid and improving the contact with the corrosion resistance evaluation liquid while ensuring the contact with atmospheric oxygen, the corrosion of the portion immersed in the evaluation liquid (corrosion resistance evaluation section) is promoted, and the metal It is possible to provide a method for simply and quickly evaluating the corrosion resistance of a coating provided on the surface of a material. Moreover, according to this invention, the corrosion-resistance evaluation apparatus which can implement the said method can be provided.

First, a method for evaluating the corrosion resistance of a coating provided on the surface of a metal material according to the present invention will be described.
In the method of the present invention, a metal material evaluation product having a surface constituted by a coating portion and an exposed portion where a bare metal is exposed is immersed in an oxygen-containing atmosphere so that only a part of the coating portion and the exposed portion are immersed. A surface having a coating part and an exposed part, which is held in a corrosion resistance evaluation liquid and immersed in the corrosion resistance evaluation liquid, is observed as a corrosion resistance evaluation part.

  In the method of the present invention, the surface of the metal material evaluated product is composed of a coating portion and an exposed portion where the metal is exposed.

  The bare metal constituting the exposed portion of the metal material evaluated product is the same kind as the corresponding metal bare metal, and is preferably made of an iron-based material. Here, the iron-based material means iron itself or an iron alloy containing iron as a main component, and the iron alloy contains carbon, silicon, magnesium, cerium, nickel, chromium, molybdenum, copper and the like together with iron. Things can be mentioned. Specific examples of the iron alloy include steel and cast iron. Examples of the steel include cold rolled steel and stainless steel. Examples of cast iron include gray cast iron, white cast iron, and mottled cast iron. , Ductile cast iron, spheroidal graphite cast iron, malleable cast iron, alloy cast iron and the like.

  On the surface of the metal material evaluation object, the coating film constituting the coating portion is the same type as the corresponding metal material surface coating, and in consideration of corrosion resistance, zinc, zinc alloy, chromium pigment, molybdenum pigment, Those formed by various organic paints are preferable, and examples of the zinc alloy include a zinc-aluminum alloy, a zinc-magnesium alloy, and a zinc-aluminum-magnesium alloy.

  The coating part is preferably formed by plating or coating, and examples of the coating method include spray coating, powder coating methods such as electrostatic coating and fluidized immersion.

  The thickness of the coating is preferably 1 to 200 μm, more preferably 5 to 100 μm, and still more preferably 10 to 50 μm.

  In the method of the present invention, as a method for obtaining a metal material evaluation product having a surface constituted by both the coating portion and the exposed portion, the method described above only on a part of the metal surface in a metal piece previously cut into a predetermined size. After forming the film by the above-mentioned method on the entire surface of the metal material by forming the film part by the above method and by using the remaining part as the exposed part, or after forming the film by the above-described method on the entire surface of the metal material, processing such as cutting and cleaving To cut out a metal piece of a predetermined size, and then subject the cut (cleaved) surface of the metal piece to a treatment such as grinding and polishing, thereby producing a metal material evaluation product whose surface is composed of a coating part and an exposed part. The method of obtaining can be mentioned. For example, as shown in FIG. 1 (a), a metal material having a coating formed on the entire surface including the α plane and the β plane by a desired method is cut at an appropriate portion to cut out a metal piece. As shown in FIG. 1 (b), a metal material having a coating surface such as an α surface and a β surface, and a cutting / polishing surface 2 in which a bare metal is exposed in the entire central portion by polishing the cut surface. Evaluation object 1 can be obtained.

  In general, in order to facilitate evaluation of corrosion resistance, the metal material evaluation product preferably has a flat surface for evaluating corrosion resistance, and more preferably a flat plate in consideration of handling during observation and measurement. In the case where the metal material evaluation product has a flat plate shape, the size is preferably about 5 to 10 mm in length, 10 to 30 mm in width, and about 2 to 5 mm in thickness.

In the method of the present invention, in the corrosion resistance evaluation solution, the metal material evaluation material having a surface constituted by the coating portion and the exposed portion is immersed in an oxygen-containing atmosphere so that only a part of the coating portion and the exposed portion are immersed. Hold on.
As the oxygen-containing atmosphere, an air atmosphere is preferable.

  As the corrosion resistance evaluation solution, a sodium chloride-containing aqueous solution is preferable, and examples of the sodium chloride-containing aqueous solution include sodium chloride alone or an aqueous solution containing sodium chloride and acetic acid.

  1.0-10 mass% is preferable, as for the density | concentration of sodium chloride in sodium chloride containing aqueous solution, 3.0-6.0 mass% is more preferable, and 4.5-5.5 mass% is further more preferable.

  In the method of the present invention, the surface having the coating part and the exposed part immersed in the corrosion resistance evaluation liquid is defined as the corrosion resistance evaluation part.

  The corrosion resistance evaluation part is preferably flat so that observation and measurement can be easily performed, and is preferably subjected to surface polishing in order to make the surface state between measurement samples uniform. The corrosion resistance evaluation part preferably has an exposed part at the center and a coating part on the outer edge. As such a corrosion resistance evaluation part, for example, a flat cutting / polishing surface 2 in which an exposed part and a coating part are formed on the outer edge as shown schematically in FIG. The immersion part when immersed in can be mentioned.

Area of the corrosion resistance evaluation unit is preferably 10 to 200 mm ^2, more preferably from 10 to 100 mm ^2, further preferably 25-50 mm ^2.

  As for the area ratio of the coating part to the exposed part in the corrosion resistance evaluation part, the area of the coating part / the area of the exposed part is preferably 1/10000 to 1/25, more preferably 1/10000 to 1/500. Preferably, it is 1/5000 to 1/1000.

  In the method of the present invention, it is preferable that the metal material evaluation product is immersed and held in a corrosion resistance evaluation solution in a state where the metal material evaluation product is embedded in the resin so that the surface having the coating portion and the exposed portion is on the front side.

  A preferred example of this aspect will be described with reference to the drawings.

  2 schematically shows a metal material evaluation object 1 having a flat cutting / polishing surface 2 in which an exposed portion is formed in the center and a coating portion is formed on the outer edge, and the surface 2 is on the front side, schematically shown in FIG. FIG. 2A is a perspective view of the evaluation test piece 4, and FIG. 2B is a cross-sectional view of the evaluation test piece 4. Yes.

  In FIG. 2, the test specimen 4 for evaluation has a cylindrical shape, but may have other shapes such as a quadrangular prism shape.

  As shown in FIG. 2, the main surface of the evaluation test piece 4 from which the surface 2 is exposed preferably has a circular shape with a diameter of 50 mm or less when the evaluation test piece 4 has a cylindrical shape. When the test specimen 4 has a quadrangular prism shape, it is preferably a quadrangular shape that is 50 mm or less in both length and width. Moreover, it is preferable that the height (thickness) of the test specimen 4 for evaluation is 10 to 40 mm.

  Examples of the resin 3 include an epoxy resin, an acrylic resin, and a phenol resin that are used as an embedded resin for tissue examination.

  As a method for producing the test specimen 4 for evaluation, for example, after embedding the metal material evaluation object 1 cut into a desired size with respect to the resin 3 in a molten state so that the surface 2 is on the front side, Examples of the method include cooling and solidifying the resin to form a predetermined shape, and then polishing the main surface including the surface 2.

  As shown in FIG. 2 (a), the edge sag preventing portion 5 is formed on the metal material evaluation object 1 so that the coating of the metal material evaluation object 1 does not sag due to the polishing process when the evaluation test piece 4 is manufactured. It is preferable to provide them close to each other.

  Examples of the edge sag preventing portion 5 include a thin plate or a linear metal piece having a composition equivalent to that of the base metal.

  Next, the test specimen 4 for evaluation is immersed in a corrosion resistance evaluation liquid in a suitable container.

  When the evaluation test piece 4 has a cylindrical shape as shown in FIG. 2, the container for accommodating the evaluation test piece 4 has the same length as the main surface diameter of the evaluation test piece 4 as shown in FIG. A cylindrical container 7 having an inner diameter of the same length, and a prismatic container whose vertical and horizontal lengths are the same as the main surface diameter of the test piece 4 for evaluation, and such a container is used. Thus, it becomes possible to fix the test specimen 4 for evaluation in the container and prevent its movement.

  Further, by making the height of the container sufficiently higher than the height (thickness) of the test specimen 4 for evaluation, the cut / polished surface 2 of the metal material evaluation object 1 can be immersed in the evaluation liquid. Become.

  Further, as in the test piece 4 for evaluation shown in FIG. 2A, a plurality of metal material evaluation products are embedded in a resin and immersed in a corrosion resistance evaluation solution, thereby simultaneously measuring the corrosion resistance of more samples. Therefore, not only the measurement time can be shortened, but also the sample can be easily handled during measurement, and the measurement error between samples can be reduced.

  In addition, in order to immerse only a part of the surface 2 in the metal material evaluation object 1 in the corrosion resistance evaluation liquid, it is preferable to use an angle adjusting jig 8 as shown in FIG. As shown in FIG. 3, in the metal material evaluation object 1 accommodated in the container 7, the angle adjusting jig 8 is placed at the lower part of the container 7 so that the bottom surface of the container 7 forms a certain angle with the horizontal plane. Only a part of the surface 2 can be immersed in the corrosion resistance evaluation liquid 6. The metal material evaluation object 1 is preferably immersed so that the exposed surface 2 and the liquid surface of the evaluation liquid form an angle of 5 ° to 45 °, and an angle of 5 ° to 30 ° is formed. It is more preferable to immerse, and it is further preferable to immerse so as to form an angle of 10 ° to 20 °. In this way, in the test specimen 4 for evaluation, the metal material evaluation object 1 is embedded so that the surface 2 having the exposed portion and the coating portion is on the front side, and the surface 2 and the evaluation liquid form a predetermined angle. By fixing the position, it becomes possible to easily observe the corrosion resistance evaluation unit as described later. The angle can be arbitrarily changed by changing the thickness of the angle adjusting jig.

In the embodiment shown in FIG. 3, the exposed portion and the coating portion are formed by the evaluation test piece 4 using the resin 3, the container 7 that can be fixed so that the evaluation test piece 4 does not move inside, and the angle adjusting jig 8. The position and angle are adjusted and held so that only a part of the surface 2 possessed can be immersed in the corrosion resistance evaluation liquid 6. For example, the arm and the position and angle of the tip can be arbitrarily adjusted. The metal material evaluation object 1 is held by a holding tool with a clip attached to the tip of the metal, and the position and angle of the tip are adjusted, so that only a part of the surface having the coating part and the exposed part is immersed in the corrosion resistance evaluation liquid. You can also
The immersion time is preferably 3 to 4 hours.

  In the method of the present invention, the metal material evaluation product is held in the corrosion resistance evaluation liquid so that only a part of the coating portion and the exposed portion is immersed, so that the portion immersed in the corrosion resistance evaluation liquid (corrosion resistance evaluation section) The corrosion resistance evaluation part forms a part exposed to an oxygen atmosphere (dry part) and promotes corrosion of the corrosion resistance evaluation part from the vicinity of the dry part. That is, in the method of the present invention, the contact with the atmospheric oxygen is ensured by the dry part, and the corrosion resistance is increased by increasing the contact amount with oxygen as compared with the case where the metal material evaluation product is completely immersed in the evaluation liquid. It is possible to promote corrosion in the evaluation section. Further, by immersing the corrosion resistance evaluation part in the corrosion resistance evaluation liquid, the contact density with the evaluation liquid is increased as compared with the case of spraying or the like, and the corrosion can be promoted.

  In the method of the present invention, it is preferable to evaluate the corrosion resistance based on the ratio of the area of the portion where red rust is generated or the area of the portion where no red rust is generated to the area of the corrosion resistance evaluation portion.

  The ratio of the area of the portion where the red rust is generated or the area of the portion where the red rust is not generated to the area of the corrosion resistance evaluation portion can be obtained by, for example, a corrosion resistance evaluation apparatus having an observation means and a measurement means.

  For example, as shown in FIG. 3, as a corrosion resistance evaluation apparatus, a container 7 containing the metal material evaluation product 1 and the corrosion resistance evaluation liquid 6 having the coating portion and the exposed portion, and an exposed portion and a coating portion of the metal material evaluation product 1. In addition to a holder such as an angle adjusting jig 8 that can adjust the position and angle of the metal material evaluation object 1 so that only a part of each of the metal material evaluation object 6 can be immersed in the corrosion resistance evaluation liquid 6, the corrosion resistance evaluation of the metal material evaluation object 1 A device having a microscope 9 and a monitor 11 that are means for observing a section, and a measuring means 12 that is electrically connected to the monitor 11 and calculates an area value based on image data of the monitor 11 can be used. The microscope 9 is preferably fixed in position by a stand 13 with an angle adjustment function.

  In the above corrosion resistance evaluation apparatus, based on the image data of the corrosion resistance evaluation section displayed on the monitor 11, the measurement means 12 is used to measure the area of the corrosion resistance evaluation section, the area where red rust is generated, and the portion where red rust is not generated. After calculating each area value such as the area of the area, the area ratio of the portion where the red rust is generated or the area ratio of the portion where the red rust is not generated is obtained with respect to the area of the corrosion resistance evaluation portion from the obtained area values. be able to.

Next, the corrosion resistance evaluation apparatus of the present invention will be described.
The corrosion resistance evaluation apparatus of the present invention is an apparatus for evaluating the corrosion resistance of a coating provided on the surface of a metal material,
A container capable of containing a metal material evaluation product and a corrosion resistance evaluation liquid, the surface of which is constituted by a coating portion and an exposed portion from which the metal is exposed;
A holder that can adjust the position and angle of the metal material evaluation product so that only a part of the coating portion and the exposed portion of the metal material evaluation product can be immersed in the corrosion resistance evaluation solution;
Observation means for observing the immersed part as a corrosion resistance evaluation part,
And a measuring unit electrically connected to the observation unit.

  The corrosion resistance evaluation apparatus of the present invention can suitably carry out the method of the present invention, and can hold a metal material evaluation product, a container that can store a corrosion resistance evaluation solution, etc., and a position and angle of the metal material evaluation product that can be adjusted. The preferred embodiment of the tool, the means for observing the portion immersed in the corrosion resistance evaluation solution as the corrosion resistance evaluation section, and the measuring means are the same as described above.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Example 1
As shown in FIG. 1A, after forming a 50 μm-thick film on the entire surface of a steel plate having a length of 5 mm, a width of 20 mm, and a thickness of 3 mm using a sacrificial anticorrosive paint containing a Zn-based metal filler, FIG. As shown in FIG. 5, five flat steel plates each having a cut surface 2 having a length of 5 mm and a width of 20 mm were cut out and used as a metal material evaluation product 1.

  As shown in FIG. 2, the five flat steel plates are embedded in parallel in a molten epoxy resin so that the cut surface 2 is on the front side, and then cooled and solidified in a mold. By polishing the main surface by a surface polishing method (surface setting step → fine polishing step → polishing step → puff finishing step), a cylindrical evaluation test piece 4 having a main surface diameter of 40 mm and a thickness of 30 mm was obtained. . As shown in FIG. 2, in order to prevent the coating of the metal material evaluation object 1 from sagging during the surface polishing, the test specimen 4 for evaluation is embedded with a steel flake adjacent to each metal material evaluation object 1, The prevention part 5 was formed.

  As shown in FIG. 3, the test specimen 4 for evaluation is placed in a cylindrical container 7 having an inner diameter of 40 mm and a height of 50 mm so that the surface having the cut and polished surface 2 faces upward. After the prismatic angle adjusting jig 8 is installed, a 5 mass% sodium chloride aqueous solution is poured into the container as a corrosion resistance evaluation solution, so that as shown in FIG. It adjusted so that only a part might be immersed in an evaluation liquid. In this example, as shown in FIG. 3, the angle adjusting jig 8 is installed at the lower part of the container 7 so that the surface 2 of the metal material evaluation object and the liquid surface of the evaluation liquid form an angle of 15 °. .

  On the other hand, as shown in FIG. 3, a microscope 13 is attached to the evaluation liquid immersion part (corrosion resistance evaluation part) of the metal material evaluation object 1 fixed so as not to move in the container 7. 9 was fixed in position, and the microscope 9 was electrically connected to the monitor 11 via the cable 10.

  In the above state, when the metal material evaluation product 1 is held in the corrosion resistance evaluation liquid 6, as shown in FIGS. 4 and 5, first, in the vicinity of the liquid surface 6a of the corrosion resistance evaluation liquid (in the vicinity of the portion exposed to the oxygen atmosphere). Then, after the red rust is generated in the Zn coating portion formed on the outer edge of the corrosion resistance evaluation portion 14 and the red rust spreads over the entire Zn coating portion (FIG. 4), the red rust 15 expands toward the center of the exposed portion of the exposed portion 2. (Figure 5).

  After holding the metal material evaluation object 1 in the corrosion resistance evaluation liquid 6 for 3 hours, the corrosion resistance evaluation unit is electrically connected to the monitor 11 from the image data of the corrosion resistance evaluation unit 14 displayed on the monitor 11. The area of 14 and the area of the part where red rust 13 did not occur after 3 hours from immersion were calculated, and the area ratio of the part where red rust did not occur relative to the area of the corrosion resistance evaluation part was determined. The results are shown in Table 1.

Comparative Example 1
When the corrosion resistance was evaluated in the same manner as in Example 1 except that the test specimen 4 for evaluation was completely immersed in the corrosion resistance evaluation liquid 6, no rust was generated in the corrosion resistance evaluation portion of the metal material evaluation product 1.

Comparative Example 2
The sacrificial anticorrosive paint used for forming the surface coating of Example 1 was applied to a flat steel plate having a length of 5 mm, a width of 20 mm, and a thickness of 3 mm so as to have a film thickness of 50 μm to form a surface coating on the entire surface.
As shown in FIG. 6, a crosscut 17 having a total length of 100 mm was formed on the steel plate 16 having the above surface coating so that two straight scratches having a length of 50 mm intersect each other.
Next, in accordance with the method described in JIS Z 2371, a 5 mass% sodium chloride aqueous solution was continuously sprayed on the steel plate 16 having the surface coating for 240 hours.
By microscopic observation, the length of the portion where red rust was not generated in the entire length of the crosscut portion was determined, and the ratio of the length of the portion where red rust was not generated relative to the entire length of the crosscut portion was determined. The results are shown in Table 1.

Example 2
The surface coating was the same as in Example 1 except that an organic coating was applied to a thickness of 40 μm on a 10 μm-thick underlayer that had been subjected to chemical conversion treatment with phosphate. The corrosion resistance was evaluated. The results are shown in Table 1.

Comparative Example 3
When the corrosion resistance was evaluated in the same manner as in Example 2 except that the evaluation test piece 4 was completely immersed in the corrosion resistance evaluation liquid 6, no rust was generated in the corrosion resistance evaluation portion of the metal material evaluation product 1.

Comparative Example 4
As in Comparative Example 2, except that a surface coating was formed by spray coating an organic paint to a thickness of 40 μm on a 10 μm-thick foundation layer that had been subjected to chemical conversion treatment with phosphate. The corrosion resistance was evaluated. The results are shown in Table 1.

  By comparing the results of Example 1 and Example 2 with the results of Comparative Example 1 and Comparative Example 3 respectively, using a metal material evaluation product and immersing only a part of the surface coating in the corrosion resistance evaluation solution It can be seen that quick evaluation is possible.

  Further, from Table 1, by comparing the results of Example 1 and Example 2 with the results of Comparative Example 2 and Comparative Example 4, respectively, the corrosion resistance evaluation by the corrosion resistance evaluation method of the present invention is the conventional salt spray test method. It can be seen that there is a good correlation with the corrosion resistance evaluation result by. In Comparative Example 2 and Comparative Example 4, the measurement time is 240 hours, whereas in Example 1 and Example 2, the measurement is completed in 3 hours. Therefore, the method of the present invention is simple. It can also be seen that the corrosion resistance can be evaluated quickly.

  ADVANTAGE OF THE INVENTION According to this invention, the method of evaluating easily and rapidly the corrosion resistance of the film provided in the metal raw material surface can be provided, and the corrosion resistance evaluation apparatus which can implement the said method can be provided.

It is a figure which shows the manufacture example of the metal raw material evaluation material used by this invention. It is a figure which shows an example of the test piece for evaluation used by this invention. It is a figure which shows an example of the corrosion resistance evaluation apparatus of this invention. It is a figure explaining the generation | occurrence | production direction of red rust in the test piece for evaluation. It is a figure explaining the example of generation | occurrence | production of red rust in the test piece for evaluation. It is a figure which shows the test piece for evaluation by a conventional method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal material evaluation thing 2 Cut surface 3 Resin 4 Evaluation test piece 5 Edge sag prevention part 6 Corrosion resistance evaluation liquid 7 Container 8 Angle adjustment jig 9 Microscope 10 Cable 11 Monitor 12 Measuring means 13 Stand 14 with angle adjustment function Corrosion resistance evaluation part 15 Red rust 16 Steel plate 17 with surface coating Cross-cut

Claims (8)

A method for evaluating the corrosion resistance of a coating provided on the surface of a metal material,
A metal material evaluation product whose surface is composed of a coating part and an exposed part where the bare metal is exposed,
In an oxygen-containing atmosphere, hold in the corrosion resistance evaluation solution so that only a part of each of the coating part and the exposed part is immersed,
A method for evaluating corrosion resistance, comprising observing a surface having a coating portion and an exposed portion immersed in the corrosion resistance evaluation solution as a corrosion resistance evaluation portion.   The corrosion resistance evaluation method according to claim 1, wherein the coating part is formed by plating or painting.   The corrosion resistance evaluation method according to claim 1, wherein the oxygen-containing atmosphere is an air atmosphere.   The corrosion resistance evaluation method according to any one of claims 1 to 3, wherein the corrosion resistance evaluation liquid is a sodium chloride-containing aqueous solution.   The corrosion resistance evaluation method according to any one of claims 1 to 4, wherein the corrosion resistance evaluation portion is planar and is subjected to surface polishing.   The said metal raw material evaluation object is immersed in a corrosion-resistant evaluation liquid in the state embedded in resin so that the surface which has a film part and an exposed part may become a front side, It hold | maintains in any one of Claims 1-5. Corrosion resistance evaluation method.   The corrosion resistance according to any one of claims 1 to 6, wherein the corrosion resistance is evaluated based on a ratio of an area of a portion where red rust is generated or an area of a portion where no red rust is generated to the area of the corrosion resistance evaluation portion. Evaluation methods. An apparatus for evaluating the corrosion resistance of a coating provided on the surface of a metal material,
A container capable of containing a metal material evaluation product and a corrosion resistance evaluation liquid, the surface of which is constituted by a coating portion and an exposed portion from which the metal is exposed;
A holder that can adjust the position and angle of the metal material evaluation product so that only a part of the coating portion and the exposed portion of the metal material evaluation product can be immersed in the corrosion resistance evaluation solution;
Observation means for observing the immersed part as a corrosion resistance evaluation part,
A corrosion resistance evaluation apparatus comprising: a measurement unit electrically connected to the observation unit.

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