Evaluation method and evaluation kit

Abstract

To provide an evaluation method and an evaluation kit capable of simply evaluating corrosiveness in a metal member containing copper.SOLUTION: An evaluation method and an evaluation kit include a step of bringing a copper-containing metal member A to be evaluated and a copper-containing metal member B into contact with a non-liquid electrolyte body, a step of measuring a potential of a contact surface between the metal member A and the electrolyte body, and a step of evaluating corrosiveness of the metal member A by using the measured potential.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an evaluation method and an evaluation kit. [Background technology]

[0002] Copper pipes have excellent properties such as corrosion resistance, workability, and thermal conductivity, and are therefore used in heat exchangers, etc. However, they can suffer from corrosion such as pitting after long-term use.

[0003] For example, Patent Document 1 describes a simple metal discriminator that is portable and can be easily carried anywhere, and has a means for measuring the potential difference between the potential of the reference metal electrode due to ionization of the surface metal of the easily detachable reference metal electrode and the potential of the metal being tested due to ionization of the surface metal of the test object, via an easily detachable electrolyte chip made of a material that absorbs and retains electrolyte solution between the easily detachable reference metal electrode and the surface metal of the test object, by contacting the surface of the metal being tested and measuring the potential difference. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-024745 A Summary of the Invention [Problem to be solved by the invention]

[0005] The method described in Patent Document 1 can distinguish between lead solder and lead-free solder, but is not intended to evaluate the corrosiveness of metal members containing copper. There was a need to establish a method for easily evaluating the corrosiveness of metal components containing copper.

[0006] An object of one embodiment of the present disclosure is to provide an evaluation method and an evaluation kit that can easily evaluate the corrosiveness of a metal member containing copper. [Means for solving the problem]

[0007] The means for solving the above problems include the following means. <1> A step of bringing a copper-containing metal member A and a copper-containing metal member B, which are to be evaluated, into contact with a non-liquid electrolyte body; a step of measuring the potential of the contact surface of the metal member A with the electrolyte body; a step of evaluating the corrosiveness of the metal member A using the measured potential; Evaluation methods, including: <2> The non-liquid electrolyte body is an absorbent body in which an electrolyte solution is absorbed in an absorbent material. <1> 2. A method for evaluating metal members according to claim 1. <3> The non-liquid electrolyte body is a gel body. <1> or <2> The evaluation method described in <4> The non-liquid electrolyte includes a water-absorbing polymer. <1> ~ <3> 1. An evaluation method according to any one of the preceding claims. <5> The non-liquid electrolyte medium comprises a polymeric material selected from agar, gelatin, starch, dextrin, and dextran; <1> ~ <4> 1. An evaluation method according to any one of the preceding claims. <6> The metal member A is a metal pipe. <1> ~ <5> 1. An evaluation method according to any one of the preceding claims. <7> Using the measured potential, the amount of carbon on the contact surface of the metal member A with the electrolyte body is evaluated. <1> ~ <6> 1. An evaluation method according to any one of the preceding claims. <8> A metal member B containing copper; a non-liquid electrolyte body; The copper-containing metal member A and the copper-containing metal member B to be evaluated are brought into contact with a non-liquid electrolyte, and the potential of the contact surface of the metal member A with the electrolyte is measured. An evaluation kit that evaluates the corrosiveness of metal member A using the measured potential. <9> The non-liquid electrolyte body is an absorbent body in which an electrolyte solution is absorbed in an absorbent material. <8> An evaluation kit for a metal member according to claim 1. <10> The non-liquid electrolyte body is a gel body. <8> or <9> The evaluation kit according to claim 1. <11> The non-liquid electrolyte includes a water-absorbing polymer. <8> ~ <10> 10. An evaluation kit according to any one of the preceding items. <12> The non-liquid electrolyte medium comprises a polymeric material selected from agar, gelatin, starch, dextrin, and dextran; <8> ~ <11> 10. An evaluation kit according to any one of the preceding items. <13> Using the measured potential, the amount of carbon on the contact surface of the metal member A with the electrolyte body is evaluated. <8> ~ <12> 10. An evaluation kit according to any one of the preceding items. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, an evaluation method and an evaluation kit are provided that can simply and easily evaluate the corrosiveness of a copper-containing metal member. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a state in which copper foil B is in contact with an electrolyte body 10. As shown in FIG. [Figure 2] FIG. 2 is a diagram showing a state in which a copper tube A and a copper foil B are in contact with an electrolyte body 10. As shown in FIG. [Figure 3] FIG. 3 is a diagram showing a method for measuring the potential at the contact surface of the copper tube A with the electrolyte body 10. As shown in FIG. [Figure 4A] FIG. 4A is a graph showing the correlation between potential difference and carbon amount, and the correlation between carbon amount and corrosivity, obtained by a method using a non-liquid electrolyte. [Figure 4B] FIG. 4B is a graph showing the correlation between potential difference and carbon amount, and the correlation between carbon amount and corrosivity, obtained by a method using a liquid electrolyte. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present disclosure will be described. These descriptions and examples are intended to illustrate the embodiment and are not intended to limit the scope of the invention. In the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of a numerical range may be replaced with a value shown in the examples. In the present specification, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0011] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0012] [Evaluation method] The evaluation method according to the present disclosure includes the steps of bringing a copper-containing metal member A and a copper-containing metal member B, which are to be evaluated, into contact with a non-liquid electrolyte (hereinafter also referred to as the "contact step"), measuring the potential of the contact surface of the metal member A with the electrolyte (hereinafter also referred to as the "measurement step"), and evaluating the corrosivity of the metal member A using the measured potential (hereinafter also referred to as the "evaluation step"). Note that "corrosivity" refers to the property of having the potential to cause corrosion.

[0013] Each step will be described below.

[0014] <Contact process> In the contacting step, the metal member A and the metal member B are brought into contact with the non-liquid electrolyte. There are no particular limitations on the contacting method as long as the metal member A and the metal member B are in contact with the electrolyte. For example, after the electrolyte body is brought into contact with the metal member A, the metal member B may be brought into contact with a portion of the electrolyte body other than the portion in contact with the metal member A. Alternatively, after the metal member B is brought into contact with the electrolyte body, the portion of the electrolyte body other than the portion in contact with the metal member B may be brought into contact with the metal member A.

[0015] (Metal component A) In the evaluation method according to the present disclosure, the metal member A is the object to be evaluated. The metal member A contains copper. The metal member A may be made of pure copper or a copper alloy.

[0016] Pure copper refers to copper (Cu) with a purity of 99.9% by mass or more. Pure copper may contain unavoidable impurities. The term "unavoidable impurities" refers to trace elements that are contained in raw materials or inevitably mixed in during the manufacturing process. Examples of unavoidable impurities include As, Sb, B, Pb, V, Zr, Mn, Mo, Hf, Ta, Bi, Ag, In, and Co. Examples of pure copper include tough pitch copper, phosphorus deoxidized copper, and oxygen-free copper.

[0017] Copper alloy refers to an alloy with a copper (Cu) purity of 50% by mass or more. Examples of copper alloys include Cu-Zn alloys (brass), Cu-Ni alloys (white copper), Cu-Ni-Zn alloys (nickel silver), Cu-Sn alloys (bronze), and Cu-Sn-P alloys (phosphor bronze). The copper alloy may also be a Cu—Sn—Ni—Zn alloy or a Cu—Si—Pb—P—Zn alloy.

[0018] In particular, the evaluation method according to the present disclosure is preferably used to evaluate the corrosiveness of a heat exchanger copper tube. From the viewpoints of workability and thermal conductivity, the heat exchanger copper tube is preferably made of pure copper, and the metal member A is preferably pure copper.

[0019] The shape of the metal member A is not particularly limited, and may be a plate, a curved shape, or a tubular shape.

[0020] According to the evaluation method of the present disclosure, it is possible to evaluate the corrosivity of the metal member A regardless of the shape of the metal member A. Conventionally, it has been difficult to evaluate the corrosivity of a metal pipe, but according to the evaluation method of the present disclosure, when the metal member A is a metal pipe, it is possible to evaluate the corrosivity of the inner wall surface of the metal pipe.

[0021] (Metal component B) In the evaluation method according to the present disclosure, metal member B is a reference metal member prepared for evaluating the corrosiveness of metal member A. Metal member B contains copper, similar to metal member A. For example, when metal member A is made of pure copper, metal member B is also preferably made of pure copper.

[0022] It is desirable that the metal members A and B have the same composition.

[0023] It is preferable that the metal member B be washed in advance. As a cleaning method, for example, a method in which the surface of the metal member B is polished with abrasive paper and then washed with a solvent such as methanol can be mentioned.

[0024] (Non-liquid electrolyte) In the present disclosure, "non-liquid" means a solid or semi-solid state that does not have fluidity at 25°C.

[0025] The non-liquid electrolyte is preferably a gel from the viewpoint of ease of contact with the metal member A and workability. Even if water is attached to the metal member A, the gel electrolyte can be brought into contact with the metal member A.

[0026] The non-liquid electrolyte body is preferably an absorbent body in which the electrolyte is absorbed into an absorbent material in order to retain the electrolyte and make it non-liquid. The electrolyte may be, for example, an aqueous solution containing cations such as sodium ions and potassium ions, anions such as hydroxide ions, bicarbonate ions, carbonate ions and sulfate ions, and water.

[0027] Examples of the absorbent material include hydrophilic fibers and water-absorbent polymers.

[0028] From the viewpoint of ease of contact with the metal member A and workability, the non-liquid electrolyte preferably contains a water-absorbent polymer.

[0029] Examples of water-absorbing polymers include (meth)acrylic polymers, vinyl polymers, gelatin, and polysaccharides. Examples of polysaccharides include agar, carrageenan, xanthan gum, pectin, locust bean gum, curdlan, guar gum, tragacanth gum, gum arabic, gellan gum, tamarind seed gum, cassia gum, tara gum, alginic acid, glucomannan, soybean polysaccharides, gelatin, pullulan, psyllium, chitosan, methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, dextrin, and dextran.

[0030] Among these, from the viewpoint of ease of contact with the metal member A and workability, the non-liquid electrolyte preferably contains a polymer material selected from agar, gelatin, starch, dextrin, and dextran.

[0031] From the viewpoint of viscosity adjustment, the electrolyte preferably contains a thickener, the content of which is adjusted appropriately.

[0032] <Measurement process> In the measurement step, the potential of the contact surface of the metal member A with the electrolyte body is measured. The potential can be measured using a commonly known potential measuring device. Specifically, the potential difference can be obtained by measuring the potential of the contact surface of metal member A with the electrolyte body, using the potential of the contact surface of metal member B with the electrolyte body as a reference.

[0033] <Evaluation process> In the evaluation step, the corrosiveness of the metal member A is evaluated using the measured potential. Specifically, the corrosiveness of the metal member A is evaluated using the potential difference obtained in the measurement step. The larger the potential difference obtained in the measurement step, the more likely it is that corrosion of the metal member A has progressed, or the more likely it is that the metal member A will corrode.

[0034] Specifically, in the evaluation step, it is preferable to use the measured potential to evaluate the amount of carbon on the contact surface between the metal member A and the electrolyte body. The greater the amount of carbon, the more advanced the corrosion of the metal member A can be determined to be.

[0035] As a method for measuring the potential on the inner wall surface of a metal pipe to be evaluated using a liquid electrolyte, for example, the following method has been used. The outer wall surface of the metal pipe is washed with an organic solvent. One opening of the metal tube is sealed. The metal tube is immersed in an electrolyte with the sealed bottom facing downwards, so that only the outer wall surface of the metal tube comes into contact with the electrolyte. The potential of the outer wall surface of the metal tube is then measured. The metal tube is removed from the electrolyte and washed. Next, an electrolyte is poured into the metal tube, and only the inner wall surface of the metal tube is brought into contact with the electrolyte. Then, the potential of the inner wall surface of the metal tube is measured. This allows the potential difference to be obtained by measuring the potential of the inner wall surface of the metal pipe with the potential of the outer wall surface of the metal pipe as a reference. When the relationship between the amount of carbon present on the inner wall surface of the metal tube and the potential difference was investigated, it was found that there was a correlation.

[0036] As described above, a method using a liquid electrolyte to measure the potential on the inner wall surface of a metal pipe to be evaluated requires a liquid electrolyte and involves many complicated steps. In contrast, the evaluation method according to the present disclosure uses a non-liquid electrolyte, allowing the potential of the metal member A to be evaluated to be measured easily. Furthermore, the potential difference obtained by the evaluation method according to the present disclosure correlates with the amount of carbon present on the surface of the metal member A, as with conventional methods. Therefore, by creating a calibration curve for the relationship between the potential difference and the amount of carbon using a metal member with a known amount of carbon and by understanding the relationship between the amount of carbon and corrosivity, the corrosivity of the contact surface of the metal member A to be evaluated and the electrolyte can be evaluated.

[0037] [Evaluation Kit] The evaluation kit according to the present disclosure includes a copper-containing metal member B and a non-liquid electrolyte body, and is an evaluation kit that measures the potential of the contact surface of metal member A with the electrolyte body by bringing the copper-containing metal member A and metal member B, which are the subject of evaluation, into contact with the non-liquid electrolyte body, and evaluates the corrosiveness of metal member A using the measured potential.

[0038] The details of the metal member A, the metal member B, and the non-liquid electrolyte body are as described above.

[0039] An example of an evaluation method using an evaluation kit according to the present disclosure will be described below with reference to FIGS.

[0040] The evaluation kit 100 includes a copper foil B and a non-liquid electrolyte body 10 . FIG. 1 is a diagram showing a state in which copper foil B is in contact with an electrolyte body 10. As shown in FIG. First, as shown in Fig. 1, an end face of the copper foil B is inserted into the electrolyte body 10 to bring the copper foil B into contact with the electrolyte body 10. To stabilize the potential, it is preferable to maintain this state for 2 to 3 minutes.

[0041] FIG. 2 is a diagram showing a state in which a copper tube A and a copper foil B are in contact with an electrolyte body 10. As shown in FIG. Next, as shown in FIG. 2, the electrolyte body 10 with the copper foil B inserted therein is adhered to the inner wall surface of the copper tube A.

[0042] FIG. 3 is a diagram showing a method for measuring the potential at the contact surface of the copper tube A with the electrolyte body 10. As shown in FIG. As shown in FIG. 3, cables 21 and 22 connected to the connection terminals of the potential measuring device 20 are connected to the copper foil B and the copper pipe A, respectively.

[0043] The potential difference is measured by the potential measuring device 20, and the corrosiveness of the copper pipe A is evaluated based on the measured potential difference. The evaluation is performed using a calibration curve prepared in advance. The calibration curve shows the relationship between the potential difference and the amount of carbon. If the measured potential difference does not fall within the corrosion judgment standard (predetermined carbon amount value, for example, 2.0 mg / m) set on the calibration curve, 2 ) is exceeded, it can be determined that there is a high possibility that corrosion is progressing. As a potential measuring device, a commercially available potentiostat or digital voltmeter can be used. There may be a plurality of corrosion determination criteria, and the method of determining the progress of corrosion or the possibility of corrosion can be changed by selecting or combining the corrosion determination criteria. [Example]

[0044] The present invention will be explained in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0045] <Preparation of electrolyte body> 50 mL of aqueous sodium sulfate solution (0.5 mol / L) was heated to 100°C in a water bath. 10 g of D(+) maltose hydrate and 10 g of D(+) glucose were added to the mixture. 1.7 g of agar was also added in several batches. The resulting mixture was boiled in a microwave oven and subjected to ultrasonic cleaning for 20 seconds. The mixture was transferred to a petri dish and allowed to stand at room temperature (25°C) for 1 hour to obtain an electrolyte. The resulting electrolyte was a gel.

[0046] <Evaluation of copper pipe corrosion>

[0047] As the metal member B, copper foil (Nilaco 99.9%) was prepared. The copper foil was polished with #1200 and #2000 polishing papers and washed with methanol. The washed copper foil was inserted into the electrolyte body and left to stand for 2 to 3 minutes to stabilize the potential, thereby preparing an evaluation kit.

[0048] The metal component A to be evaluated has a carbon content of 1.1 mg / m 2 , 1.5 mg / m 2 , 6.3 mg / m 2 A copper pipe sample was prepared. Each copper tube sample was washed with methanol.

[0049] The electrolyte body with the copper foil inserted was adhered to the inner wall surface of the copper tube sample.

[0050] A potentiostat (model number "vsp-300", manufactured by Biologic) was used as the potential measuring device. A cable was connected to the copper pipe sample and the copper foil, and the potential was measured.

[0051] FIG. 4A is a graph showing the correlation between potential difference and carbon amount, and the correlation between carbon amount and corrosivity, obtained by a method using a non-liquid electrolyte. FIG. 4B is a graph showing the correlation between potential difference and carbon amount, and the correlation between carbon amount and corrosivity, obtained by a method using a liquid electrolyte.

[0052] In both Figure 4A and Figure 4B, the rightmost plot shows the carbon content of 6.3 mg / m 2 The center plot shows the results for a copper pipe sample with a carbon content of 1.5 mg / m 2 The leftmost plot shows the results for a copper pipe sample with a carbon content of 1.1 mg / m 2 The results are from a copper pipe sample. In addition, the carbon content is 2.0 mg / m 2 The dotted line at the position indicates the corrosion criteria.

[0053] The higher the carbon content of the copper pipe sample, the larger the potential difference. Figures 4A and 4B show that the method of the example using a non-liquid electrolyte exhibits similar behavior to the conventional method using a liquid electrolyte. While the conventional method using a liquid electrolyte requires an electrolyte solution and involves many complicated steps, the method of the example using a non-liquid electrolyte is extremely simple. According to the evaluation method of the present disclosure, potential can be measured very easily, and the corrosivity of the copper-containing metal member being evaluated can be evaluated based on the potential. [Explanation of symbols]

[0054] A Copper tube B Copper foil 10 Electrolyte body 20 Potential measuring device 21, 22 Cable 100 Evaluation Kits

Claims

1. a step of bringing a copper-containing metal member A and a copper-containing metal member B, which are to be evaluated, into contact with a non-liquid electrolyte body; measuring the potential of the contact surface of the metal member A with the electrolyte body; a step of evaluating the corrosiveness of the metal member A using the measured potential; Evaluation methods, including:

2. 2. The method for evaluating a metal member according to claim 1, wherein the non-liquid electrolyte is an absorbent body in which an electrolytic solution is absorbed in an absorbent material.

3. The evaluation method according to claim 1 , wherein the non-liquid electrolyte body is a gel body.

4. The evaluation method according to claim 1 , wherein the non-liquid electrolyte contains a water-absorbent polymer.

5. The evaluation method according to claim 1 , wherein the non-liquid electrolyte contains a polymer material selected from the group consisting of agar, gelatin, starch, dextrin, and dextran.

6. The evaluation method according to any one of claims 1 to 5, wherein the metal member A is a metal pipe.

7. 6. The evaluation method according to claim 1, wherein the amount of carbon on the contact surface of the metal member A with the electrolyte body is evaluated using the measured potential.

8. a metal member B containing copper; a non-liquid electrolyte body; a copper-containing metal member A and a copper-containing metal member B to be evaluated are brought into contact with the non-liquid electrolyte body, and a potential of a contact surface of the copper-containing metal member A with the electrolyte body is measured; The evaluation kit evaluates the corrosiveness of the metal member A using the measured potential.

9. 9. The metal component evaluation kit according to claim 8, wherein the non-liquid electrolyte body is an absorbent body in which an electrolytic solution is absorbed in an absorbent material.

10. The evaluation kit according to claim 8 , wherein the non-liquid electrolyte body is a gel body.

11. The evaluation kit according to claim 8 , wherein the non-liquid electrolyte contains a water-absorbent polymer.

12. The evaluation kit according to claim 8 , wherein the non-liquid electrolyte contains a polymer material selected from the group consisting of agar, gelatin, starch, dextrin, and dextran.

13. The evaluation kit according to any one of claims 8 to 12, wherein the measured potential is used to evaluate the amount of carbon on the contact surface of the metal member A with the electrolyte body.

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