JP2021076510A - Test device and test method - Google Patents

Abstract

To provide a test device capable of highly accurately performing electrochemical measurement on a metal in contact with a water-containing powder.SOLUTION: Disclosed is a test device 1 for performing electrochemical measurement with a test piece 11 as a working electrode using an electrochemical cell C having a flat surface 13a and holding the metal test piece 11 so that the surface 11a is exposed parallel to the flat surface 13a. This test device includes: a cylindrical press die 20; a loading plate 30 having a shape to be fitted to the press die 20: a counter electrode 31 formed on one surface of the loading plate 30; and a moisture content measuring probe 32 arranged on the side on which the counter electrode 31 of the loading plate 30 is formed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a test apparatus and a test method for performing electrochemical measurement of a metal.

Corrosion caused by contact with electrochemically active powders can be problematic for metallic materials. For example, equipment used in steelworks may be corroded by the accumulation of coke powder, coal powder, and the like. In addition, steel pipe piles, steel sheet piles, etc. buried in the soil may be corroded by contact with fine particles in the soil.

As a method for investigating metal corrosion caused by contact with such powder, an embedding test in which a metal test piece is embedded in a test tank filled with powder is performed.

For example, in JP-A-2017-215300, JP-A-2016-224001, and JP-A-2011-75477, actual soil and simulated soil are filled in a test tank to adjust the water content of those soils. However, a method for evaluating the corrosion resistance of steel in soil by controlling the temperature and partial pressure of oxygen is disclosed. Japanese Patent Application Laid-Open No. 2017-72592 states that a plurality of layers of simulated soil are formed in a test tank, and the air volume in the soil is changed in each layer to reproduce oxygen concentration microcell corrosion, and the corrosion resistance of steel in the soil is improved. The method of evaluation is disclosed.

JP-A-2017-215300 Japanese Unexamined Patent Publication No. 2016-22401 Japanese Unexamined Patent Publication No. 2011-75477 Japanese Unexamined Patent Publication No. 2017-72592

In the burial test, since the filling degree and pressure of the powder are not constant in the test tank, there is a problem that the corrosion form of the test piece is not uniform and it is difficult to ensure the reproducibility of the test.

In addition, the powder contains water due to rainfall and dew condensation, resulting in various water-containing environments. In order to reproduce the corrosive environment in the water-containing powder, the corrosion test is carried out by filling the powder (gel) with the water content changed in advance, but the water-containing powder expands. Therefore, the environment may be different from that in the actual powder or soil.

An object of the present invention is to provide a test apparatus and a test method capable of performing electrochemical measurement of a metal in contact with a water-containing powder with high accuracy.

The test apparatus according to the embodiment of the present invention uses an electrochemical cell having a flat surface and holding a metal test piece so that the surface is exposed in parallel with the flat surface, and the test piece is actuated. A test device for performing electrochemical measurement as described above, which comprises a tubular press die, a loading plate having a shape that fits the press die, and a counter electrode formed on one surface of the above-mentioned loading plate. , The water content measuring probe arranged on the side where the counter electrode is formed of the load plate described above.

The test method according to the embodiment of the present invention is a test method using the above-mentioned test apparatus so that the exposed surface of the test piece is inside the opening on the flat surface of the electrochemical cell. A step of arranging the press die, a step of filling the inside of the press die with an admixture of a test solution and a powder, a step of applying a load to the admixture by the above-mentioned loading plate, and the water-containing material. The present invention includes a step of measuring the water content of the admixture with a rate measuring probe and a step of performing electrochemical measurement using the test piece as a working electrode.

According to the present invention, the electrochemical measurement of the metal in contact with the water-containing powder can be performed with high accuracy.

FIG. 1 is a perspective view showing a schematic configuration of a test apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. FIG. 3 is a diagram for explaining a test method using the test apparatus of FIG. FIG. 4 is a diagram for explaining a test method using the test apparatus of FIG. FIG. 5 is a diagram for explaining a test method using the test apparatus of FIG. FIG. 6 is a diagram for explaining a test method using the test apparatus of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated. The dimensional ratio between the constituent members shown in each figure does not necessarily indicate the actual dimensional ratio.

[Test equipment]
FIG. 1 is a perspective view showing a schematic configuration of a test apparatus 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. The test device 1 includes a press die 20, a loading plate 30, a counter electrode 31, a water content measuring probe 32, and a gas introduction nozzle 33.

The test device 1 is a test device for performing an electrochemical measurement using the test piece 11 as a working electrode by using the electrochemical cell C in which the metal test piece 11 is held.

The electrochemical cell C has a flat surface 13a. In FIG. 1, the electrochemical cell C is shown as a cylinder, but the shape of the electrochemical cell C is not limited to this. The electrochemical cell C may have a flat surface 13a having a certain size, and for example, a protrusion or a recess may be present on the outside of the flat surface 13a.

The test piece 11 is made of a metal to be measured. The test piece 11 has a surface 11a exposed to the outside, and the surface 11a is held in the electrochemical cell C so as to be parallel to the flat surface 13a of the electrochemical cell C. In FIG. 1, the test piece 11 is shown as a cylinder, but the shape of the test piece 11 is not limited to this.

In addition to the test piece 11, the electrochemical cell C includes a reference electrode 12 arranged around the test piece 11 and a holding body 13 for holding the test piece 11 and the reference electrode 12.

The reference electrode 12 is arranged around the test piece 11 with the holding body 13 in between. Like the test piece 11, the reference electrode 12 also has a surface not covered by the holding body 13, and the reference electrode 12 is held by the holding body 13 so that this surface is parallel to the flat surface 13a. The reference electrode 12 is not limited to this, but is, for example, a silver / silver chloride electrode. Although the reference electrode 12 is shown as a cylinder in FIG. 1, the shape of the reference electrode 12 is not limited to this.

The holding body 13 holds the test piece 11 and the reference electrode 12 in an electrically insulated state. The retainer 13 is made of, for example, a resin. The holding body 13 is formed with a through hole 13b penetrating in the thickness direction. FIG. 1 illustrates a case where a total of 12 through holes 13b are formed along the circumferential direction of the holding body 13, but the number and positions of the through holes 13b are arbitrary.

The press die 20 has a tubular shape that opens vertically. In FIG. 1, the press die 20 is shown as a cylinder, but the shape of the press die 20 is not limited to this.

The opening of the press die 20 is preferably larger than the surface 11a of the test piece 11 and smaller than the flat surface 13a of the electrochemical cell C. For example, when the press die 20 has a cylindrical shape and the test piece 11 and the electrochemical cell C have a cylindrical shape, as shown in FIG. 2, the inner diameter d1 of the press die 20 is the surface 11a of the test piece 11. It is preferably larger than the outer diameter d2 and smaller than the outer diameter d3 of the electrochemical cell C.

As described above, the press die 20 does not have to have a cylindrical shape, and the test piece 11 and the electrochemical cell C do not have to have a cylindrical shape. When the surface 11a of the press die 20 and the test piece 11 has an arbitrary shape, "the opening of the press die 20 is larger than the surface 11a" means that the press die 20 is placed on the electrochemical cell C. When viewed from a direction perpendicular to the surface 11a, it means that the contour of the test piece 11 has a shape that can be included in the inner peripheral surface of the press die 20. Similarly, when the flat surface 13a of the pressing die 20 and the electrochemical cell C has an arbitrary shape, "the opening of the pressing die 20 is smaller than the flat surface 13a" means that the pressing die 20 is pressed onto the electrochemical cell C. When the die 20 is arranged and viewed from a direction perpendicular to the surface 11a, it means that the inner peripheral surface of the press die 20 has a shape that can be included in the contour of the flat surface 13a.

As will be described later, the press die 20 is used to fill the inside with an admixture of powder and a test solution and apply a load to the admixture. Therefore, the press die 20 preferably has a predetermined rigidity according to the load applied to the admixture. The press die 20 also preferably has an insulating property on the inner peripheral surface in contact with the admixture. As the press die 20, for example, a stainless steel die whose inner peripheral surface is coated with a resin or the like can be used. The entire press die 20 may be an insulator.

The loading plate 30 has a shape that fits into the opening of the press die 20. The loading plate 30 transmits the load from the press device A to apply the load to the admixture arranged inside the press die 20. The press device A is, for example, a hydraulic cylinder. The press device A may be a weight.

It is preferable that the loading plate 30 has an insulating property on the surface in contact with the admixture (the surface on the side on which the counter electrode 31 is formed). As the loading plate 30, for example, one made of stainless steel whose one side is coated with resin or the like can be used. The loading plate 30 may be entirely an insulator.

A counter electrode 31 is formed on one surface of the loading plate 30. The counter electrode 31 is, for example, a platinum-plated electrode, but is not limited to this. The counter electrode 31 is preferably formed in the same area as the surface 11a of the test piece 11 which is the working electrode.

A water content measuring probe 32 is fixed to the loading plate 30. The water content measuring probe 32 is arranged so that the detection unit is located on the side where the counter electrode 31 is formed so that the water content of the admixture filled inside the press die 20 can be measured. In FIGS. 1 and 2, the case where the number of the water content measuring probes 32 is two is shown, but the number of the water content measuring probes 32 may be one, or three or more. May be good.

A gas introduction nozzle 33 is further fixed to the loading plate 30. The gas introduction nozzle 33 penetrates the loading plate 30 and is configured so that gas can be introduced inside the press die 20.

The test apparatus 1 may further include a heating apparatus (not shown) for heating the press die 20.

[Test method]
Hereinafter, a test method using the test apparatus 1 will be described with reference to FIGS. 3 to 6.

First, the press die 20 is placed on the flat surface 13a of the electrochemical cell C so that the surface 11a of the test piece 11 is inside the opening. Then, the inside of the press die 20 is filled with the admixture G of the test liquid and the powder (see FIGS. 3 and 4). At this time, the powder and the test liquid may be mixed in advance on the outside of the press die 20 and then filled, or the powder and the test liquid may be mixed on the inside of the press die 20. ..

The powder constituting the admixture G is a powder simulating a powder existing in an environment in which the metal to be measured is arranged. This powder may be collected from a real environment. The test solution constituting the admixture G is prepared by dissolving a predetermined amount of electrolyte in a solvent such as water, and for example, a saline solution can be used.

The loading plate 30 is placed on the admixture G, and a load is applied to the admixture G by the press device A (see FIGS. 5 and 6). At this time, a part of the water content of the admixture G is discharged from the through hole 13b. When a load of a predetermined magnitude is applied, the reduction distance of the press device A is measured to determine the thickness of the admixture G.

The water content of the admixture G is measured by the water content measuring probe 32. If necessary, the water content of the admixture G may be adjusted by heating the press die 20 or blowing dry gas from the gas introduction nozzle 33. Then, the electrochemical measurement is performed using the test piece 11 as a working electrode. More specifically, the test piece 11, the reference electrode 12, and the counter electrode 31 are connected to a potentiostat or a galvanostat to perform electrochemical measurement.

[Effect of test equipment]
The test apparatus 1 uses an electrochemical cell C having a flat surface 13a and holding a metal test piece 11 so that the surface 11a is exposed in parallel with the flat surface 13a. This is a test device for performing chemical measurements. The test device 1 includes a press die 20, a loading plate 30, a counter electrode 31, and a water content measuring probe 32.

According to this configuration, by arranging the press die 20 on the flat surface 13a of the electrochemical cell C, the powder and the test are performed in the space composed of the flat surface 13a and the inner peripheral surface of the press die 20. The admixture G with the liquid can be accommodated. At this time, by arranging the press die 20 so that the surface 11a of the test piece 11 is inside the opening, the surface 11a and the admixture G can be brought into contact with each other.

By applying a load to the loading plate 30 in this state, a predetermined pressure can be applied to the admixture G. As a result, a constant filling atmosphere can be reproduced, so that the electrochemical measurement of the metal in contact with the admixture G can be performed with high accuracy. Therefore, it is possible to electrochemically evaluate the diffusion of the solution component and the gas component reaching the metal surface. Further, the electrochemical measurement can be performed while changing the magnitude of the pressure applied to the admixture G and the water content of the admixture G.

In the above embodiment, the case where the test apparatus 1 includes the gas introduction nozzle 33 has been described. According to this configuration, dry gas or the like can be blown from the gas introduction nozzle 33 as described above. However, depending on the purpose of the test, the gas introduction nozzle 33 may not be provided.

In the above embodiment, the case where the through hole 13b is formed in the holding body 13 of the electrochemical cell C has been described. If the through hole 13b is formed, water can be smoothly discharged from the admixture G. However, even when the through hole 13b is not formed, it is possible to volatilize the water through the gap between the pressing die 20 and the loading plate 30 or the like.

The test apparatus 1 according to the embodiment of the present invention and the test method using the test apparatus 1 have been described above. According to this embodiment, the electrochemical measurement of the metal in contact with the water-containing powder can be performed with high accuracy.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to these examples.

An electrochemical cell was prepared by embedding a cylindrical test steel material (SM490 steel) having an outer diameter of 10 mm with a resin. A cylindrical press die was placed on top of this electrochemical cell. As the press die, a stainless steel die whose inner peripheral surface was coated with PTFE was used. 3 g of zinc oxide particles having an average particle size of 1.0 μm and 10 ml of a 0.01% NaCl aqueous solution were mixed and filled in a press die.

A loading plate was placed on the admixture and a load of 20.0 kN was applied. Then, the whole test apparatus was charged into a constant temperature bath at 60 ° C. In some tests, dry air was blown into the press die.

Moisture content measurement and electrochemical measurement were performed immediately after pressurization, after 6 hours, and after 24 hours, respectively. Table 1 shows the relationship between the water content and the current density of -800 mV vs. SSE after cathode polarization.

The embodiments of the present invention have been described above. The above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented without departing from the spirit of the present invention.

1 Test equipment C Electrochemical cell 11 Test piece 11a Surface 12 Reference electrode 13 Holder 13a Flat surface 13b Through hole 20 Press die 30 Loading plate 31 Counter electrode 32 Moisture content measurement probe 33 Gas introduction nozzle G admixture A Press equipment

Claims (5)

An electrochemical measurement device for performing electrochemical measurement using the test piece as a working electrode using an electrochemical cell having a flat surface and holding a metal test piece so that the surface is exposed in parallel with the flat surface. There,
Cylindrical press die and
A loading plate having a shape that fits into the press die,
With the counter electrode formed on one surface of the load plate described above,
A test device including a water content measuring probe arranged on the side where the counter electrode is formed of the load plate described above. The test apparatus according to claim 1.
A test device further including a gas introduction nozzle penetrating the load plate described above. The test apparatus according to claim 1 or 2, wherein the opening of the press die is larger than the exposed surface of the test piece and smaller than the flat surface of the electrochemical cell. The test apparatus according to any one of claims 1 to 3.
A test device in which a through hole is formed in the electrochemical cell. A test method using the test apparatus according to any one of claims 1 to 4.
A step of arranging the press die on the flat surface of the electrochemical cell so that the exposed surface of the test piece is inside the opening.
The step of filling the inside of the press die with an admixture of the test liquid and the powder, and
The step of applying a load to the admixture by the load plate described above, and
A step of measuring the water content of the admixture with the water content measuring probe, and
A test method comprising a step of performing an electrochemical measurement using the test piece as a working electrode.

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