JP2014206507A - Electrochemical measurement electrode and electrochemical measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical measurement electrode having high reliability and a high degree of soundness capable of performing stable electrochemical measurement under conditions of wide temperature range and under influence of radiation.SOLUTION: The electrochemical measurement electrode is used for electrochemical measurement of a material with an electrode disposed in water sample. A sample electrode constituting the electrochemical measurement electrode has a core wire 7 of an inorganic insulation cable 20 having a metal sheath 2. The inorganic insulation cable 20 has a ceramic coating 5 at the end thereof. The front end of the core wire 7 is joined with a sample electrode portion 1 made of an electrochemical measurement material and the metal sheath 2 and the core wire 7 are electrically insulated from each other.

Description

The present invention is intended for systems and equipment exposed to cooling water in various plants such as nuclear power plants, thermal power plants, and chemical plants. The corrosion strength of metal materials is electrochemically measured in a high temperature environment or in an environment affected by radiation. TECHNICAL FIELD The present invention relates to an electrochemical measurement electrode and an electrochemical measurement apparatus for performing measurement.

In general, in order to understand the corrosion resistance of metal structures exposed to various water environments, measurement of corrosion potential, potential application, or current in test solutions adjusted in the laboratory or in water environments where actual equipment is exposed. Electrochemical measurements such as measurements involving polarization by application are performed. Usually, in the corrosion potential measurement, a reference electrode and a sample electrode made of a target material are placed facing each other in a test tank into which a test solution is injected, and a potential difference between these electrodes is measured with a potentiometer. In addition, in electrochemical measurements involving polarization due to potential application or current application, a sample electrode and a counter electrode (such as a platinum plate) made of the target material are installed in a test tank into which a test solution is injected, and a reference electrode tank in which a reference electrode is installed A salt bridge is provided between the test tank and the liquid junction between them. One or two intermediate tanks may be provided between the reference electrode tank and the test tank via a liquid junction.

The sample electrode is usually a strip-shaped metal piece with a measuring lead attached by soldering or spot welding, and a predetermined area of the attachment part and the sample electrode is covered and sealed with an epoxy resin or the like. The target metal surface is exposed. Conductive wires for measurement are vinyl, epoxy resin, copper wire coated with polytetrafluoroethylene (PTFE), and the like. About a counter electrode, conducting wire (platinum wire etc.) is attached to the platinum board, and a conducting wire part is similarly coat | covered with vinyl, epoxy polytetrafluoroethylene (PTFE), etc.

As the reference electrode, a metal / hardly soluble salt / aqueous solution electrode such as a silver / silver chloride electrode (Ag / AgCl) or a sweet potato electrode (Hg / Hg2Cl2) is usually used. As the internal solution (aqueous solution), a potassium chloride (KCl) aqueous solution having a predetermined concentration such as saturation or 1 N is generally used. The electrode potential is uniquely determined by the measurement temperature and the activity of chloride ions in the aqueous solution. When the silver chloride electrode is used at a high temperature of about 250 ° C or higher, the internal solution is pure water and measured. There is an example in which the electrode potential relative to the chloride ion concentration due to dissolution of silver-silver chloride at a temperature is used as a reference potential. In addition, since the platinum electrode exhibits a redox potential in an aqueous environment, it may be used as a kind of reference electrode in a hydrogen-rich test solution.

JP 2010-175416 A JP 2012-37364 A

As described above, in the prior art, epoxy resin, vinyl, polytetrafluoroethylene (PTFE) or the like is used for the measurement system, and when the ambient temperature of the measurement environment or the test water temperature is high, the deterioration and deterioration occur. Sealing properties and insulating properties are also deteriorated, and the characteristics as an electrode are impaired. In addition, these materials do not have radiation resistance, and are not suitable for measurement in a radiation atmosphere or in water where nuclides including radioactivity are present.

The present invention has been made in consideration of the above-described circumstances, and is capable of performing stable electrochemical measurement with high reliability and soundness in a wide range of temperature conditions and environments affected by radiation. An object is to provide an electrochemical measurement electrode and an electrochemical measurement device.

In order to solve the above-described problems, an electrochemical measurement electrode according to the present invention is an electrochemical measurement electrode used for electrochemical measurement of a material performed by arranging an electrode in sample water. The sample electrode is a core material of an inorganic insulated cable having a metal sheath, and a ceramic coating is applied to the end portion of the inorganic insulated cable, and the tip of the core wire is joined to the sample electrode portion made of the material to be measured. The metal sheath and the core wire are electrically insulated.

Moreover, the electrochemical measurement apparatus according to the present invention is an electrochemical measurement apparatus for a material that is formed by arranging an electrode in sample water, wherein the electrochemical measurement electrode and the reference electrode are arranged opposite to each other in a measurement environment, Signals from the core wires of the respective electrodes are connected to an electrochemical measuring device to perform electrochemical measurement.

According to the electrochemical measurement electrode and the electrochemical measurement device according to the present invention, it is possible to perform stable measurement with high reliability and soundness in an environment affected by a wide range of temperature conditions and radiation.

The cross-sectional structure of the sample electrode in 1st Example which concerns on this invention is shown, (a) is a side view, (b) is a longitudinal cross-sectional view, (c) is AA arrow sectional drawing of (b). The cross-sectional structure of the counter electrode made from platinum in 2nd Example which concerns on this invention is shown, respectively (a) is a side view, (b) is a longitudinal cross-sectional view, (c) is BB arrow sectional drawing of (b). . The cross-sectional structure of the electrochemical measuring electrode in the 3rd Example which concerns on this invention is shown, respectively (a) is a side view, (b) is a longitudinal cross-sectional view, (c) is CC arrow cross-section of (b). Figure. The cross-sectional structure of the electrochemical measuring electrode in the 4th Example which concerns on this invention is shown, (a) is a longitudinal cross-sectional view, respectively, (b) is DD sectional view taken on the line of (a). The schematic diagram which shows the structure of the electrochemical measuring apparatus in the 6th Example which concerns on this invention.

Embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected about the same component and the detailed description of the component is abbreviate | omitted.

Example 1
FIG. 1 is a cross-sectional configuration diagram of a sample electrode constituting the electrochemical measurement electrode in the first embodiment of the present invention. 1A is a side view, FIG. 1B is a longitudinal sectional view, and FIG. 1C is a sectional view taken along line AA in FIG.

In FIG. 1, a sample electrode unit 1 is a plate-shaped test piece made of a material to be measured. The signal extraction cable 20 is an inorganic insulating cable having a metal sheath 2, and a core wire 3 made of the same material as that of the sample electrode portion 1 is disposed at the center of an inorganic material 4 such as MgO. The tip of the core wire 3 is joined to the end of the sample electrode portion 1 by a method such as spot welding.

As shown in FIG. 1C, the terminal portion of the signal take-out cable 20 is coated with the ceramic coating layer 5. The ceramic to be coated is one or more kinds of ceramics selected from ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Cr ₃ C ₂ , and Cr ₂ O ₃ , and the thickness is about 0.2 mm as an example. However, it can be appropriately changed according to the test environment and the test time.

The coating of the ceramic coating layer 5 is any one of gas spraying, arc spraying, plasma spraying, high-speed flame spraying, reduced pressure plasma spraying, physical vapor deposition (PVD), chemical vapor deposition (CVD), and sputtering. Techniques can be used. Two or more coating methods may be used in combination. A particularly suitable coating method is a thermal spraying method. The ceramic coating method is not limited to the above method. The ceramic coating layer 5 is a slurry-like ceramic powder, gas spraying method, arc spraying method, plasma spraying method, high-speed flame spraying method, reduced pressure plasma spraying method, physical vapor deposition method, chemical vapor deposition method, sputtering method, Alternatively, it may be formed using a combination of two or more of these methods.

The ceramic coating layer 5 provides high durability of the electrode structure even in a wide range of temperature conditions and environments affected by radiation, ensures electrical insulation between the sample electrode and other metals such as core wires, and measures corrosion potential. And can be used as a highly reliable and sound sample electrode in electrochemical measurements involving polarization.

(Example 2)
FIG. 2 is a cross-sectional configuration diagram of a platinum counter electrode constituting the electrochemical measurement electrode in the second embodiment of the present invention. 2A is a side view, FIG. 2B is a longitudinal sectional view, and FIG. 2C is a sectional view taken along the line BB in FIG. 2B.

In FIG. 2, the signal extraction cable 21 of the platinum counter electrode 6 is an inorganic insulating cable having the metal sheath 2 as in the first embodiment, and the platinum core wire 7 is provided at the center of the inorganic material 4 such as MgO. Has been placed.

As shown in FIG. 2C, the terminal portion of the signal take-out cable 21 is coated with the ceramic coating layer 5. The ceramic material and covering method are the same as those of the ceramic covering layer 5 of the first embodiment. The tip of the core wire 7 is joined to the end of the platinum counter electrode 6 by a method such as spot welding.

The ceramic coating layer 5 ensures high durability of the electrode structure even in an environment affected by a wide range of temperature conditions and radiation, ensures electrical insulation between the platinum counter electrode and other metals such as a core wire, and corrosion potential. It can be used as a highly reliable and sound counter electrode or a platinum counter electrode in electrochemical measurements involving measurement and polarization.

Example 3
FIG. 3 is a cross-sectional configuration diagram of a sample electrode or a platinum counter electrode constituting an electrochemical measurement electrode in a third embodiment of the present invention. 3A is a side view, FIG. 3B is a longitudinal sectional view, and FIG. 3C is a sectional view taken along the line CC of FIG. 3B.

In FIG. 3, the electrode portion 8 is a plate-shaped test piece made of a material to be measured, or a platinum counter electrode portion. The signal extraction cable 22 is an inorganic insulating cable having a metal sheath 2 as in the first embodiment, and the core wire 9 is disposed at the center of the inorganic material 4 such as MgO. In this case, the core wire 9 is generally made of a material to be measured in the case of a sample electrode and platinum in the case of a counter electrode made of platinum, but different materials can be used for each. The tip end of the core wire 9 is joined to the end portion of each electrode portion by a method such as spot welding.

In the present embodiment, the ceramic coating layer 5 is coated on the terminal portion 5a of the signal extraction cable 22, the entire surface 5b of the exposed core wire 9, and the entire region 5c other than the exposed surface 10 serving as the test target surface or the electrode reaction surface. Is done. The material of the ceramic and the coating method are the same as in Example 1.

The ceramic coating layer 5 ensures high durability of the electrode structure even in an environment affected by radiation over a wide range of temperature conditions, and ensures electrical insulation between the electrode and other metals such as a core wire, thereby defining the electrode area. Thus, it can be used as a sample electrode having high reliability and soundness in electrochemical measurement accompanied with polarization.

Example 4
FIG. 4 is a cross-sectional configuration diagram of an electrochemical measurement electrode constituting an electrochemical measurement electrode in a fourth embodiment of the present invention. 4A is a longitudinal sectional view, and FIG. 4B is a sectional view taken along the line DD in FIG.

In FIG. 4, a signal take-out cable 23 is a two-core inorganic insulated cable having a metal sheath 2, one of which is a core wire 3 made of the same material as the sample electrode and the other is a core wire 7 made of platinum. It arrange | positions so that it may not contact with others inside the inorganic materials 4, such as.

As shown in FIG. 4B, the terminal portion of the signal take-out cable 23 is coated with the ceramic coating layer 5. The material of the ceramic and the coating method are the same as in the first to third embodiments. The tip of the core wire 3 is joined to the end of the sample electrode portion 1 made of the material to be measured, and the tip of the core wire 7 is joined to the end of the platinum counter electrode portion 6 by a method such as spot welding. The arrangement of the sample electrode portion 1 and the platinum counter electrode portion 6 is appropriately adjusted according to the positional relationship between the reference electrode and the reference electrode that are opposed to each other by electrochemical measurement.

The fourth embodiment is not limited to the illustrated electrodes. Any of the electrodes shown in Examples 1 to 3 can be configured. Further, the number of core wires of the inorganic insulated cable is not limited to two. The number of core wires may be three or more, one of which may be a counter electrode made of platinum, and the other may be composed of sample electrodes of a plurality of types of materials. The ceramic coating layer 5 provides high durability of the electrode structure even in a wide range of temperature conditions and environments affected by radiation, ensuring electrical insulation between both electrodes and other metals such as core wires, and measuring corrosion potential. And can be used as an electrode with high reliability and soundness in electrochemical measurements involving polarization.

(Example 5)
FIG. 5 is a schematic diagram showing a configuration of an electrochemical measurement device constituting an electrochemical measurement electrode in a fifth embodiment of the present invention.

In FIG. 5, an electrode mounting seat 11 as a measurement target part is provided in a plant system, a part of the device 12, or a system branched from them, and is a signal that is an inorganic insulated cable for extracting an electrode signal. The take-out cables 20, 21, 22, 23 are guided to the outside through the joint 13. In the joint 13, the metal sheath 2 of the signal take-out cables 20, 21, 22, and 23 is tightened by a method such as caulking to form a boundary with the aqueous environment 14 that is an internal medium.

The electrode mounting seat 11 is provided with the sample electrode 1 connected to the single-core signal extraction cable 20 shown in the above embodiment and the platinum counter electrode 6 connected to the single-core signal extraction cable 21. A matching electrode 15 that operates in a measurement environment is installed to counteract. As the reference electrode, a metal / hardly molten salt / aqueous solution electrode such as a silver-silver chloride electrode or a metal oxide electrode such as Fe / Fe ₃ O ₄ or Cu / Cu ₂ O can be used.

Using these electrodes, combining a plurality of electrodes within the electrodes, and connecting the core wire of the cable from the electrodes to an electrochemical measuring instrument 16 such as a potentiostat, galvanostat, electrometer, etc. constitutes an electrochemical measuring device To do.

With these configurations, it is possible to perform highly reliable electrochemical measurement such as polarization curve measurement and corrosion potential measurement in a wide range of temperature conditions and in an environment affected by radiation. The present invention is not limited to the above embodiment. In place of the sample electrode of the one-core inorganic insulated cable and the counter electrode made of platinum, the electrochemical measurement electrode connected to the plurality of cores shown in Example 4, for example, the two-core signal extraction cable 23 can be used as described above. Similar effects can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Sample electrode part, 2 ... Metal sheath, 3 ... Core wire, 4 ... Inorganic material, 5 ... Ceramic coating layer, 6 ... Platinum counter electrode part, 7 ... Core wire, 8 ... Electrode part, 9 ... Core wire, 10 ... Exposure Surface, 11 ... Electrode mounting seat, 12 ... Plant system / equipment, 13 ... Joint, 14 ... Water environment, 15 ... Reference electrode, 16 ... Electrochemical measuring instrument, 20, 21, 22, 23 ... Signal extraction cable.

Claims (10)

In an electrochemical measurement electrode used for electrochemical measurement of a material performed by placing an electrode in sample water, the sample electrode constituting the electrochemical measurement electrode is a core wire of an inorganic insulated cable having a metal sheath as a measurement target material. A ceramic coating is applied to the end portion of the inorganic insulated cable, the tip of the core wire is joined to a sample electrode portion made of a material to be measured, and the metal sheath and the core wire are electrically insulated. Electrochemical measurement electrode. In the electrochemical measurement electrode used for the electrochemical measurement of the material performed by arranging the electrode in the sample water, the platinum counter electrode constituting the electrochemical measurement electrode is a platinum wire as the core wire of the inorganic insulated cable having a metal sheath. The end of the inorganic insulated cable is coated with ceramics, the tip of the core wire is joined to a platinum counter electrode made of platinum, and the metal sheath and the platinum wire are electrically insulated. Electrochemical measurement electrode. In an electrochemical measurement electrode used for electrochemical measurement of a material performed by placing an electrode in sample water, the sample electrode constituting the electrochemical measurement electrode is a core wire of an inorganic insulated cable having a metal sheath as a measurement target material. ,
Ceramic coating is applied to the entire end area of the inorganic insulating cable, the entire surface of the exposed core wire, the exposed surface to be the test object surface,
An electrochemical measurement electrode, wherein a tip end of the core wire is joined to a sample electrode portion made of a material to be measured, and the metal sheath and the core wire are electrically insulated. In the electrochemical measurement electrode used for the electrochemical measurement of the material performed by arranging the electrode in the sample water, the sample electrode constituting the electrochemical measurement electrode is made of a core of an inorganic insulated cable having a metal sheath other than the material to be measured As the material of
Ceramic coating is applied to the entire end area of the inorganic insulating cable, the entire surface of the exposed core wire, the exposed surface to be the test object surface,
An electrochemical measurement electrode, wherein a tip end of the core wire is joined to a sample electrode portion made of a material to be measured, and the metal sheath and the core wire are electrically insulated. In the electrochemical measurement electrode used for the electrochemical measurement of the material performed by placing the electrode in the sample water, the platinum counter electrode constituting the electrochemical measurement electrode is made of an inorganic insulated cable having a metal sheath with a core wire other than platinum. As material,
Ceramic coating is applied to the entire region other than the exposed surface that becomes the electrode reaction surface, the terminal portion of this inorganic insulated cable, the entire surface of the exposed core wire,
An electrochemical measurement electrode, characterized in that the tip of the core wire is joined to a plate-shaped test piece made of platinum, and the metal sheath and the core wire are electrically insulated. In an electrochemical measurement electrode used for electrochemical measurement of a material performed by arranging an electrode in sample water, the inorganic insulated cable having a metal sheath has two or more cores, one of which is a platinum counter electrode, and the other is one type. Is connected to a plurality of types of sample electrodes, the end of each inorganic insulated cable is coated with ceramics, and the metal sheath is electrically insulated from the entire core wire. electrode. The ceramic constituting the ceramic coating is one or more kinds of ceramics selected from ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Cr ₃ C ₂ , and Cr ₂ O _3. The electrochemical measurement electrode according to any one of 1 to 6. The ceramic coating may be any one of gas spraying method, arc spraying method, plasma spraying method, high-speed flame spraying method, low pressure plasma spraying method, physical vapor deposition method, chemical vapor deposition method, sputtering method, or two of them. The electrochemical measurement electrode according to any one of claims 1 to 6, wherein the electrochemical measurement electrode is formed by combining a plurality of methods. The ceramic coating layer constituting the ceramic coating is made of a slurry-like ceramic powder by gas spraying method, arc spraying method, plasma spraying method, high-speed flame spraying method, reduced pressure plasma spraying method, physical vapor deposition method, chemical vapor deposition method, sputtering method. The electrochemical measurement electrode according to any one of claims 1 to 6, wherein the electrode is formed by any method or a combination of two or more of these methods. In an electrochemical measurement apparatus for materials performed by arranging an electrode in sample water, at least the electrochemical measurement electrode according to any one of claims 1 to 9 and a reference electrode are arranged to face each other in a measurement environment, An electrochemical measuring apparatus characterized in that a signal from an electrode core wire is connected to an electrochemical measuring instrument to perform electrochemical measurement.

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