Method for extracting precipitate and / or inclusion, method for quantitatively analyzing precipitate and / or inclusion, and electrolyte

Abstract

The present invention extracts precipitates and / or inclusions in a metallic material by electrolyzing an electrolytic solution. The electrolytic solution contains an adsorbent physically adsorbed and / or chemically adsorbed onto any metal other than the base metal of the metallic material. Thereby, quantitative analysis of the extracted precipitates and / or inclusions can be performed with good accuracy.

Description

Technical Field

[0001] The present invention relates to a method for extracting precipitates and / or inclusions, a method for quantitatively analyzing precipitates and / or inclusions, and an electrolytic solution. Background Art

[0002] Precipitates and / or inclusions (hereinafter also referred to as "precipitates, etc.") present in metallic materials significantly affect the properties of metallic materials (e.g., fatigue properties, hot workability, cold workability, deep drawability, machinability, electromagnetic properties, etc.) depending on their amounts present.

[0003] In particular, in the case where the metallic material is a steel material, technologies for improving the properties of steel materials by using trace amounts of precipitates and technologies for controlling the morphology of inclusions have been significantly developed in recent years.

[0004] Along with this, control of precipitates, etc. is strictly carried out in the manufacturing process of steel materials. For this purpose, it is necessary to quantitatively analyze precipitates, etc. with high precision.

[0005] Generally, in order to quantitatively analyze precipitates, etc. in metallic materials, first, precipitates, etc. are extracted. Then, the extracted precipitates, etc. are filtered and trapped using a filter, and quantitative analysis is performed.

[0006] Methods for extracting precipitates, etc. can be roughly classified into an acid decomposition method, a halogen method, and an electrolysis method.

[0007] Among them, the electrolysis method (refer to Patent Document 1) for extracting precipitates, etc. in metallic materials by electrolysis can stably extract precipitates, etc., and thus is often used.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010 - 151695 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] When extracting (electrolytic extraction) precipitates, etc. in metallic materials by electrolysis and quantitatively analyzing the extracted precipitates, etc., the quantitative analysis values sometimes deviate significantly from the expected values.

[0013] The present invention has been completed in view of the above aspects, and an object thereof is to provide a method for extracting precipitates, etc. that can quantitatively analyze the extracted precipitates and / or inclusions (precipitates, etc.) with good accuracy.

[0014] In addition, an object of the present invention is also to provide a method for quantitatively analyzing precipitates and the like using the above extraction method and an electrolytic solution used in the above extraction method.

[0015] Means for Solving the Problem

[0016] The present inventors conducted intensive studies and found that the above object can be achieved by adopting the following configuration.

[0017] That is, the present invention provides the following [1] to

[11] .

[0018] [1] A method for extracting precipitates and / or inclusions, which is a method for extracting precipitates and / or inclusions in a metal material by electrolysis using an electrolytic solution, wherein the electrolytic solution contains an adsorbent physically adsorbed and / or chemically adsorbed on any metal other than the base metal of the metal material.

[0019] [2] The method for extracting precipitates and / or inclusions according to the above [1], wherein the electrolytic solution contains a solvent, and the specific gravity of the adsorbent is greater than the specific gravity of the solvent.

[0020] [3] The method for extracting precipitates and / or inclusions according to the above [1] or [2], wherein the electrolytic solution contains a reagent that forms a complex with the base metal.

[0021] [4] The method for extracting precipitates and / or inclusions according to any one of the above [1] to [3], wherein the metal material is a steel material.

[0022] [5] The method for extracting precipitates and / or inclusions according to the above [4], wherein the any metal is Cu.

[0023] [6] A method for quantitatively analyzing precipitates and / or inclusions, which quantitatively analyzes the precipitates and / or inclusions extracted by the extraction method according to any one of the above [1] to [5].

[0024] [7] An electrolytic solution, which is an electrolytic solution for extracting precipitates and / or inclusions in a metal material by electrolysis, and contains an adsorbent physically adsorbed and / or chemically adsorbed on any metal other than the base metal of the metal material.

[0025] [8] The electrolytic solution according to the above [7], which contains a reagent that forms a complex with the base metal.

[0026] [9] The electrolytic solution according to the above [7] or [8], which contains a solvent, and the specific gravity of the adsorbent is greater than the specific gravity of the solvent.

[0027]

[10] The electrolyte according to any one of [7] to [9] above, wherein the metal material is a steel material.

[0028]

[11] The electrolyte according to

[10] above, wherein the arbitrary metal is Cu.

[0029] Advantages of the Invention

[0030] According to the present invention, it is possible to perform quantitative analysis on the precipitates and the like extracted with good accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a characteristic X-ray image of Cu of the precipitate and the like of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0032] [Insight of the Inventor]

[0033] As described above, when electrolytically extracting (electrolytic extraction) precipitates and the like in a metal material and performing quantitative analysis on the extracted precipitates and the like, the quantitative analysis value sometimes deviates significantly from the expected value.

[0034] Specifically, for example, when electrolyzing a steel material to extract precipitates such as CuS, Cu2S, (Mn,Cu)S, and MnS, the quantitative analysis value sometimes has an error.

[0035] In order to clarify the reason, the inventor of the present invention performed a composition analysis on the steel material before electrolysis and the electrolytic residue containing the electrolytically extracted precipitates and the like using a scanning electron microscope (SEM) and a transmission electron microscope (TEM).

[0036] As a result, it was found that in the electrolytic residue, metal Cu particles that are not observed in the steel material exist at a high frequency mixed with the extracted precipitates and the like (see reference Figure 1 ).

[0037] Regarding the phenomenon that metal Cu particles that do not exist in the steel material exist in the electrolytic residue, the inventor of the present invention considered as follows.

[0038] Based on the observation results of SEM and TEM, it is presumed that Cu exists in a solid solution state in the steel material. When the steel material is electrolyzed, Cu is dissolved into the electrolyte together with Fe, which is the matrix metal of the steel material.

[0039] At this time, when the solubility of Cu in the electrolytic solution is low, Cu exceeding the solubility precipitates and further aggregates to form metal Cu particles of nanometer size. The surface energy of the metal Cu particles of nanometer size is high. Therefore, the formed metal Cu particles adhere to the surface of the steel material and are extracted as electrolytic residues mixed in the precipitates and the like which are the original analysis targets. Thus, an error occurs in the quantitative analysis value.

[0040] The present inventors further conducted research.

[0041] Specifically, an electrolytic solution containing an adsorbent that selectively adsorbs (physically adsorbs and / or chemically adsorbs) to the metal Cu causing the error is used to electrolyze the steel material.

[0042] As a result, it is possible to suppress the adhesion of metal Cu particles to the surface of the steel material and to achieve good precision in the quantitative analysis of precipitates and the like.

[0043] The present invention has been completed based on the above insights.

[0044] Hereinafter, embodiments of the present invention (hereinafter also simply referred to as "the present invention") will be described.

[0045] [Metal materials, etc.]

[0046] In the following description, as the "metal material", there is no particular limitation, and examples thereof may include steel materials such as hot-rolled steel sheets and cold-rolled steel sheets.

[0047] The "base metal" of the metal material is the element contained in the largest amount in the metal material. For example, when the metal material is a steel material, it is Fe.

[0048] The "arbitrary metal" other than the base metal of the metal material is the above-mentioned metal causing the error, which is hereinafter also referred to as the "obstructing metal". There is no particular limitation on the obstructing metal. For example, when the metal material is a steel material, Cu and the like can be cited.

[0049] As the "precipitates and / or inclusions" (precipitates, etc.) in the metal material, there is no particular limitation. For example, when the metal material is a steel material, CuS, Cu2S, (Mn,Cu)S, MnS, etc. can be cited.

[0050] [Electrolytic solution]

[0051] The electrolytic solution of the present invention is an electrolytic solution for extracting precipitates and / or inclusions in a metal material by electrolysis, and contains an adsorbent that physically adsorbs and / or chemically adsorbs to an arbitrary metal other than the base metal of the above-mentioned metal material.

[0052] <Electrolyte>

[0053] The electrolyte of the present invention substantially contains an electrolyte.

[0054] As the electrolyte, there is no particular limitation, and conventionally known electrolytes can be used. Examples include tetramethylammonium chloride, sodium chloride, potassium bromide, etc.

[0055] <Solvent>

[0056] The electrolyte of the present invention substantially contains a solvent.

[0057] As the solvent, there is no particular limitation, and solvents of conventionally known electrolytes can be used. Examples include non-aqueous solvents or aqueous solvents (water). As non-aqueous solvents, for example, non-aqueous solvents having a hydroxyl group such as methanol, ethanol, propanol, and butanol can be preferably listed.

[0058] <Reagent>

[0059] The electrolyte of the present invention preferably contains a reagent (hereinafter also simply referred to as "reagent") that forms a complex with the base metal of the metal material. Thereby, the reattachment or re-precipitation of the base metal dissolved in the electrolyte onto the surface of the metal material is suppressed.

[0060] As the reagent, there is no particular limitation. For example, acetylacetone, salicylic acid, methyl salicylate, maleic acid, citric acid, sodium citrate, etc. can be preferably listed.

[0061] The content of the reagent is not particularly limited. From the viewpoint of the need to form a complex with the base metal, it is preferably 1% or more, more preferably 5% or more, and further preferably 10% or more based on the mass ratio to the solvent.

[0062] On the other hand, from the viewpoints of economic rationality, environmental load, etc., it is preferably 50% or less, more preferably 30% or less based on the mass ratio to the solvent.

[0063] <Base electrolyte>

[0064] The electrolyte of the present invention is preferably composed mainly of a base electrolyte.

[0065] The base electrolyte contains at least the above-mentioned electrolyte and solvent, and may further contain the above-mentioned reagent.

[0066] As the base electrolyte, there is no particular limitation. Examples include non-aqueous solvent-based electrolytes such as AA series (acetylacetone - tetramethylammonium chloride - methanol) electrolyte, MS series (methyl salicylate - salicylic acid - tetramethylammonium chloride - methanol) electrolyte, MA series (maleic anhydride - tetramethylammonium chloride - methanol) electrolyte, etc.; aqueous solvent-based electrolytes such as citric acid electrolyte, hydrochloric acid electrolyte, etc.

[0067] <Adsorbent>

[0068] The adsorbent contained in the electrolyte of the present invention is physically adsorbed and / or chemically adsorbed to substances that impede the metal. Physical adsorption is adsorption based on van der Waals forces. Chemical adsorption is adsorption based on chemical bonds.

[0069] It should be noted that adsorption of the adsorbent (physical adsorption and / or chemical adsorption) to the base metal is not excluded. That is, the adsorbent can be adsorbed not only to the metal that impedes (any metal other than the base metal of the metal material) but also to the base metal of the metal material.

[0070] Examples of the adsorbent that is at least physically adsorbed to the metal that impedes (hereinafter also referred to as "physical adsorbent") include porous materials such as activated carbon, silica, activated alumina, synthetic zeolite, and porous organic compounds.

[0071] As the adsorbent that is at least chemically adsorbed to the metal that impedes (hereinafter also referred to as "chemical adsorbent"), a compound having a functional group that specifically coordinates with the metal that impedes is preferred. As a specific example of the chemical adsorbent, when the metal that impedes is Cu, silica having a mercapto group (-SH group) can be preferably cited.

[0072] The specific gravity of the adsorbent is preferably greater than the specific gravity of the solvent.

[0073] As described later, the metal material is taken out of the electrolyte after electrolysis. At this time, when the specific gravity of the adsorbent is greater than the specific gravity of the solvent, the adsorbent precipitates and is not easily attached to the metal material, so it is preferred.

[0074] Regarding the pore diameter of the adsorbent (especially the physical adsorbent), from the viewpoint of adsorption capacity, it is preferably 100 nm or less in diameter, more preferably 50 nm or less in diameter. On the other hand, it is preferably 0.5 nm or more in diameter, more preferably 1 nm or more in diameter.

[0075] The pore diameter of the adsorbent is determined by measurement using the gas adsorption method.

[0076] From the viewpoint of easy dispersion in the electrolyte, the average particle diameter of the adsorbent is preferably small.

[0077] However, as described later, a filter is sometimes used to filter the adsorbent. In this case, the average particle diameter of the adsorbent is preferably equal to or larger than the pore diameter of the filter. Specifically, it is more preferably 3 μm or more, and further preferably 5 μm or more. In this case, the upper limit is not particularly limited, for example, it is 300 μm or less, preferably 250 μm or less.

[0078] The average particle diameter of the adsorbent is determined by measurement using the laser diffraction / scattering method.

[0079] The content of the adsorbent in the electrolysis of the present invention is not particularly limited. From the viewpoint of facilitating the contact between the adsorbent and the interfering metal, it is preferably 0.01 g or more, more preferably 0.1 g or more, relative to 100 mL of the base electrolyte.

[0080] On the other hand, from the viewpoint of good workability, the content of the adsorbent in the electrolysis of the present invention is preferably 5 g or less, more preferably 1 g or less, relative to 100 mL of the base electrolyte.

[0081] [Extraction method]

[0082] The method for extracting precipitates and / or inclusions of the present invention (hereinafter, for convenience, referred to as "the extraction method of the present invention") is a method for extracting precipitates and / or inclusions in a metal material by electrolysis using an electrolyte, wherein the above-mentioned electrolyte contains an adsorbent physically adsorbed and / or chemically adsorbed on any metal other than the matrix metal of the above-mentioned metal material.

[0083] The above-mentioned electrolyte of the present invention is the electrolyte used in the extraction method of the present invention.

[0084] <Preparation of test specimen to be tested>

[0085] In the extraction method of the present invention, first, it is preferable to cut the metal material into test pieces of appropriate size and perform grinding, washing, drying, etc. Hereinafter, the test piece of the metal material after performing grinding, etc. is also referred to as "the test specimen to be tested".

[0086] In the case of quantitative analysis of precipitates, etc., it is preferable to measure the mass of the test specimen to be tested before electrolysis.

[0087] <Electrolysis>

[0088] Next, using the electrolyte of the present invention, electrolysis (constant potential electrolysis or constant current electrolysis) is performed with the test specimen to be tested as the anode.

[0089] The electrolysis amount is not particularly limited. Usually, the test specimen to be tested is electrolyzed by about 0.1 g to about 1 g. The electrolysis amount can be appropriately adjusted according to the amount of the electrolyte, electrolysis conditions, the type of the test specimen (metal material), the estimated value of the amount of precipitates, etc.

[0090] During electrolysis, it is preferable to stir the electrolyte using a magnetic stirrer or the like. Thereby, the precipitation of the adsorbent is suppressed, and the adsorbent is uniformly dispersed in the electrolyte and easily contacts the interfering metal.

[0091] During electrolysis, precipitates, etc. contained in the test specimen to be tested do not dissolve into the electrolyte, but adhere to the surface of the test specimen as electrolysis residues.

[0092] On the other hand, it hinders the dissolution of the metal into the electrolytic solution but is captured by the adsorbent. Therefore, it is possible to inhibit the attachment of the hindering metal to the test sample.

[0093] <Separation of precipitates, etc.>

[0094] After electrolysis of a specified amount, the remaining part of the test sample is gently taken out from the electrolytic solution in such a way that the electrolytic residue (precipitates, etc.) attached to the remaining part of the test sample does not fall off into the electrolytic solution, and is immediately immersed in the dispersion liquid.

[0095] By immersing the remaining part of the test sample in the dispersion liquid, the electrolytic residue (precipitates, etc.) attached to the remaining part of the test sample is separated from the remaining part of the test sample and dispersed in the dispersion liquid.

[0096] As the dispersion liquid, there is no particular limitation, and conventionally known dispersion liquids can be used, and for example, methanol can be cited.

[0097] In order to quickly separate all the precipitates, etc. from the remaining part of the test sample, it is preferable to ultrasonically oscillate the dispersion liquid in which the remaining part of the test sample is immersed.

[0098] When all the precipitates, etc. are separated from the remaining part of the test sample, the remaining part of the test sample exhibits a metallic luster. Therefore, the ultrasonic oscillation time is based on this.

[0099] Then, the remaining part of the test sample is taken out from the dispersion liquid. It is preferable to thoroughly wash and dry the taken-out remaining part of the test sample using methanol or the like.

[0100] In the case of quantitatively analyzing the precipitates, etc., the mass of the remaining part of the dried test sample is measured and subtracted from the mass of the test sample before electrolysis, thereby obtaining the electrolysis mass.

[0101] In one separation step (immersion and preferably ultrasonic oscillation), the remaining part of the test sample sometimes does not exhibit a metallic luster.

[0102] Specifically, for example, the following situation: Since there are many precipitates, etc., after one separation step, the precipitates, etc. cannot be completely separated, and it is speculated that precipitates, etc. remain on the surface of the remaining part of the test sample.

[0103] In this case, it is preferable to separately prepare the dispersion liquid and repeat the separation step multiple times until the remaining part of the test sample exhibits a metallic luster.

[0104] <Collection of precipitates, etc.>

[0105] The dispersion liquid (the dispersion liquid in which precipitates etc. are dispersed) after taking out the remaining part of the test sample to be tested is filtered using a filter (for example, suction filtration), whereby precipitates etc. are trapped on the filter.

[0106] Among precipitates etc., precipitates etc. with a size of 10 nm or less are likely to aggregate. Therefore, the pore size of the filter used for trapping precipitates etc. does not need to be below the size of the assumed precipitates etc., and it can be selected according to the average particle size of the precipitates etc.

[0107] Before filtering to trap precipitates etc., it is preferable to pre-filter the dispersion liquid using a filter with a pore size of about 5 μm. Thereby, the adsorbent (the adsorbent that is inevitably attached to the test sample and dispersed in the dispersion liquid in the separation step) can be removed, and thus the accuracy of quantitative analysis is better.

[0108] [Quantitative analysis method]

[0109] The method for quantitatively analyzing precipitates and / or inclusions of the present invention (hereinafter, for convenience, referred to as "the quantitative analysis method of the present invention") is a method for quantitatively analyzing precipitates and / or inclusions extracted by the above extraction method of the present invention.

[0110] In the quantitative analysis method of the present invention, it is preferable to dissolve the precipitates etc. extracted by the above extraction method of the present invention according to a conventional method and perform quantitative analysis.

[0111] The dissolution of precipitates etc. can use a conventionally known aqueous acid solution or aqueous alkali solution, and is appropriately selected according to the target element for which quantitative analysis is performed.

[0112] As the method for quantitative analysis, for example, inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry, etc. can be preferably cited.

[0113] Examples

[0114] Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the examples described below.

[0115] <Inventive Example 1>

[0116] In Inventive Example 1, the electrolyte A described later was used to extract precipitates etc. from the test sample to be tested and perform quantitative analysis. Specifically, it is as follows.

[0117] 《Preparation of test sample》

[0118] An ingot having the composition shown in Table 1 below (the balance being Fe and unavoidable impurities) is produced by vacuum melting. After heating the produced ingot to 1200 °C, hot rolling is carried out to produce a hot-rolled steel sheet with a thickness of 3 mm.

[0119] A specimen for cross-sectional observation is cut out from the produced hot-rolled steel sheet. The cut specimen is observed using SEM, and as a result, it is confirmed that all the precipitates and the like are MnS.

[0120] Next, a test piece with dimensions of 30 mm × 30 mm is cut out from the produced hot-rolled steel sheet, and the surface is polished to prepare a specimen to be tested.

[0121] 《Electrolytic Extraction》

[0122] 0.1 g of silica with a mercapto group (R-Cat-Sil MP, manufactured by Kanto Chemical Co., Inc., average particle size 5 μm), which is used as an adsorbent (chemical adsorbent), is added to 100 mL of a citric acid electrolyte (10 mass% sodium citrate - 1 mass% potassium bromide - pure water. Here, the pH is adjusted to 4 using citric acid. The same applies hereinafter) to prepare electrolyte A.

[0123] Using the prepared electrolyte A, the specimen to be tested is subjected to constant current electrolysis under the condition of a current density of 20 mA / cm 2 ².

[0124] After electrolyzing 0.1 g of the specimen to be tested, the remaining part of the specimen to be tested taken out from electrolyte A is immersed in methanol as a dispersion liquid, and ultrasonic oscillation is carried out for 2 minutes. It is confirmed that a metallic luster appears on the remaining part of the specimen to be tested. In this way, the precipitates and the like attached to the remaining part of the specimen to be tested are separated and dispersed into the dispersion liquid. Then, the remaining part of the specimen to be tested is taken out from the dispersion liquid.

[0125] Next, the dispersion liquid after taking out the remaining part of the specimen to be tested is filtered through a filter with a pore size of 5 μm to remove the adsorbent. Further, the filtrate is filtered through a filter with a pore size of 0.2 μm, and the precipitates and the like are trapped on the filter.

[0126] 《Quantitative Analysis》

[0127] The trapped precipitates and the like together with the filter are placed in a beaker, 20 mL of nitric acid is added, and it is heated at 100 °C for 30 minutes to dissolve it. After heating, the filter is taken out from the beaker, and the nitric acid attached to the filter is rinsed off with pure water.

[0128] For the liquid in the beaker, quantitative analysis is carried out using an ICP emission spectrometer (ICPS-8100, manufactured by Shimadzu Corporation) to determine the Cu amount (unit: mass%) of the precipitates and the like trapped on the filter.

[0129] The above electrolytic extraction and quantitative analysis were repeated three times, and the average value of the three times was taken as the Cu content. The smaller the Cu content, the better the accuracy of the quantitative analysis can be evaluated.

[0130] In addition, the standard deviation (unit: mass%) of the Cu content for the three times was calculated. The smaller the value of the standard deviation, the better the accuracy of the quantitative analysis can be evaluated.

[0131] The results are all shown in Table 2 below.

[0132] <Example 2>

[0133] 5.0 g of activated carbon (activated carbon, manufactured by Fujifilm Wako Pure Chemical Corporation, average particle size 30 - 150 μm) with a pore diameter of 1 - 50 nm as an adsorbent (physical adsorbent) was added to 100 mL of a citric acid electrolyte solution to prepare electrolyte B.

[0134] Except for using electrolyte B instead of electrolyte A, electrolytic extraction and quantitative analysis were carried out in the same manner as in Example 1. The results are shown in Table 2 below.

[0135] However, in Example 2, since the particle size and specific gravity of the adsorbent are larger than those of the solvent of electrolyte B and it is easy to precipitate, during electrolysis, a magnetic stirrer was used to stir electrolyte B at a rotation speed of 200 rpm.

[0136] <Comparative Example 1>

[0137] An adsorbent was not added, and 100 mL of a citric acid electrolyte solution was used as electrolyte C.

[0138] Except for using electrolyte C instead of electrolyte A, electrolytic extraction and quantitative analysis were carried out in the same manner as in Example 1. The results are shown in Table 2 below.

[0139] However, in Comparative Example 1, after electrolysis, for the dispersion liquid after taking out the test sample to be tested, without filtering (removing the adsorbent) using a filter with a pore diameter of 5 μm, filtering was carried out using a filter with a pore diameter of 0.2 μm, and precipitates and the like were trapped on the filter.

[0140] [Table 1]

[0141]

[0142] [Table 2]

[0143] Electrolyte Cu content [mass%] Standard deviation [mass%] Inventive Example 1 A 0.0073 0.0003 Inventive Example 2 B 0.0025 0.0010 Comparative Example 1 C 0.0304 0.0094

[0144] <Summary of Evaluation Results>

[0145] As can be seen from Table 2 above, in Invention Example 1 and Invention Example 2, the amount of Cu in the precipitate and the like is less than that in Comparative Example 1, and the value of the standard deviation is also small, indicating excellent precision in quantitative analysis.

[0146] When comparing Invention Example 1 and Invention Example 2, Invention Example 2 using electrolyte B has better precision in quantitative analysis than Invention Example 1 using electrolyte A.

[0147] In Comparative Example 1, elemental analysis of the precipitate and the like trapped on the filter was performed using the X-ray analysis device attached to the SEM, and a characteristic X-ray image of Cu was obtained.

[0148] Figure 1 It is the characteristic X-ray image of Cu in the precipitate and the like of Comparative Example 1. As Figure 1 shown, in Comparative Example 1, metallic Cu particles and the precipitate and the like coexist in a mixed manner.

Claims

1. A method for extracting precipitates and / or inclusions, which is a method for extracting precipitates and / or inclusions in a metal material by electrolysis using an electrolyte. Among them, the electrolyte contains an adsorbent physically adsorbed and / or chemically adsorbed onto any metal other than the base metal of the metal material, the adsorbent physically adsorbed onto the any metal is a porous material, the porous material is activated carbon, silica, activated alumina, synthetic zeolite or a porous organic compound, the adsorbent chemically adsorbed onto the any metal is silica having a mercapto group, the any metal is Cu.

2. The method for extracting precipitates and / or inclusions according to claim 1, wherein, the electrolyte contains a solvent, and the specific gravity of the adsorbent is greater than the specific gravity of the solvent.

3. The method for extracting precipitates and / or inclusions according to claim 1 or 2, wherein, the electrolyte contains a reagent that forms a complex with the base metal.

4. The method for extracting precipitates and / or inclusions according to claim 1 or 2, wherein, the metal material is a steel material.

5. The method for extracting precipitates and / or inclusions according to claim 3, wherein, the metal material is a steel material.

6. A method for quantitative analysis of precipitates and / or inclusions, which quantitatively analyzes the precipitates and / or inclusions extracted by the extraction method according to any one of claims 1 to 5.

7. An electrolyte, which is an electrolyte for extracting precipitates and / or inclusions in a metal material by electrolysis, and contains an adsorbent physically adsorbed and / or chemically adsorbed onto any metal other than the base metal of the metal material, the adsorbent physically adsorbed onto the any metal is a porous material, the porous material is activated carbon, silica, activated alumina, synthetic zeolite or a porous organic compound, the adsorbent chemically adsorbed onto the any metal is silica having a mercapto group, the any metal is Cu.

8. The electrolyte according to claim 7, wherein, contains a reagent that forms a complex with the base metal.

9. The electrolyte according to claim 7 or 8, wherein contains a solvent, and the specific gravity of the adsorbent is greater than the specific gravity of the solvent.

10. The electrolyte according to claim 7 or 8, wherein, the metal material is a steel material.

11. The electrolyte according to claim 9, wherein, the metal material is a steel material.

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