Cleaning agent and cleaning method for oxygen-free copper for superconducting material

Abstract

The invention discloses a cleaning agent and a cleaning method for oxygen-free copper for a superconducting material, and belongs to the technical field of pretreatment of raw materials of superconducting wires. The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride and water. The concentration of ammonium persulfate in the cleaning agent is 150-210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15-25 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.5-3.0 g / L. The cleaning method comprises the steps that the cleaning agent is used for cleaning, then diluted hydrochloric acid is used for cleaning, the cleaning effect of the cleaning method is good, impurities and oxide skin on the surface of the oxygen-free copper material can be removed, and the weight content of copper in the cleaned oxygen-free copper material reaches 97.82%. The oxygen-free copper material cleaned through the cleaning method is high in oxidation resistance and uniform in surface quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of pretreatment of raw materials for superconducting wire materials, and relates to a cleaning agent and a cleaning method for oxygen-free copper used in superconducting materials. Background Art

[0002] Oxygen-free copper is a metallic material with high electrical conductivity, high thermal conductivity, and good processing performance. The copper content is greater than 99.95%, with a relatively high purity, and the oxygen content is less than 0.003%. It has been widely used in the fields of electronics, electricity, communication, and construction. Due to the active chemical properties of copper, it is prone to oxidation in the air, resulting in the yellowing and darkening of the material color, and affecting its electrical conductivity and service life.

[0003] Before assembling oxygen-free copper for superconducting materials, high requirements are placed on the surface quality of the material. It is necessary to remove oil, ash, and oxide scales to achieve a uniform, bright, natural color, remove adsorbed water and gas, control surface impurity elements, and resist oxidation. At the same time, a certain and uniformly distributed surface roughness needs to be maintained on the surface to improve the bonding between materials during subsequent assembly and stretching processes. These requirements pose relatively high technical requirements for the cleaning liquid formulation and cleaning process.

[0004] Currently, the commonly used methods for cleaning the surface of oxygen-free copper include cleaning with nitric acid solution. However, nitric acid cleaning has problems such as difficult dissolution of residual acid ions on the surface, difficult control of antioxidant properties during and after the cleaning process, large corrosion rate, and difficulty in ensuring the uniformity of surface roughness after cleaning. Therefore, providing a cleaning process and cleaning agent with good cleaning effect, high antioxidant performance, and uniform surface quality of materials is of great significance for the application of oxygen-free copper in superconducting materials. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a cleaning agent and a cleaning method for oxygen-free copper used in superconducting materials. The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and water; the concentration of ammonium persulfate in the cleaning agent is 150 - 210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15 - 25 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.5 - 3.0 g / L. The cleaning method includes: cleaning with the above cleaning agent, and then performing cleaning with dilute hydrochloric acid. The cleaning method of the present invention has a good cleaning effect, can remove surface impurities and oxide scales of oxygen-free copper materials, and the oxygen-free copper materials after being cleaned by the cleaning method of the present invention have high antioxidant performance and uniform surface quality of materials.

[0006] To achieve the technical object of the present invention, on the one hand, the present invention provides a cleaning agent for oxygen-free copper used in superconducting materials. The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and water; the concentration of ammonium persulfate in the cleaning agent is 150 - 210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15 - 25 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.5 - 3.0 g / L.

[0007] Specifically, the persulfate ions in the cleaning agent solution of the present invention undergo a strong oxidation-reduction reaction with copper, causing corrosion on the surface of oxygen-free copper to achieve the cleaning purpose. After the ammonium persulfate solution acts on copper, it can ensure the surface microchemical state properties required before the assembly of superconducting materials, make the surface chemical properties of the material stable, and ensure anti-oxidation after cleaning. The concentration of ammonium persulfate provided by the present invention is moderate, which ensures the corrosion and cleaning ability of the cleaning agent and can also prevent salts from remaining on the surface of oxygen-free copper due to saturation. The present invention controls the thickness of the corrosion layer on the surface of oxygen-free copper by adjusting the concentrations of various components, the solution temperature, and the cleaning time, ensuring that the required surface roughness of the oxygen-free copper material is obtained, and avoiding excessive, too small, or uneven surface roughness.

[0008] Specifically, adding a certain proportion of hydrochloric acid to the cleaning agent of the present invention can effectively inhibit the conversion of copper ions generated during the corrosion process into copper hydroxide precipitate and suspension in the solution, and ensure the rapid and uniform corrosion of the oxide scale, ensuring the stability and uniformity of the cleaning quality. Adding a small amount of strong electrolyte sodium chloride to the cleaning agent solution to adjust the solution polarity and the uniformity of the solubility on the surface of the material can greatly improve the consistency of the corrosion states at different positions on the surface of the material.

[0009] On the other hand, the present invention claims a cleaning method for oxygen-free copper used in superconducting materials, specifically including the following steps:

[0010] S1: First add pure water into a corrosion-resistant tank lined with fluoroplastics or PVC, then slowly add hydrochloric acid and stir to dissolve the hydrochloric acid evenly, then slowly add ammonium persulfate and stir evenly, and finally slowly add sodium chloride and stir evenly to obtain a cleaning agent. The concentration of ammonium persulfate in the cleaning agent is 150 - 210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15 - 25 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.5 - 3.0 g / L.

[0011] S2: Control the temperature of the cleaning agent solution at 10 - 25 °C, immerse the oxygen-free copper material in the cleaning solution for 3 - 5 minutes, and control the thickness of the corrosion layer on the surface of the oxygen-free copper at 15 - 25 μm.

[0012] S3: Transfer the oxygen-free copper material after the cleaning in S2 into a dilute hydrochloric acid solution with a pH of 0.5 - 2.0, a temperature of 10 - 20 °C, and a concentration of 1 - 4% within 30 seconds, and clean it for 1 - 2 minutes, then perform water washing and drying. The drying temperature is 55 - 65 °C, and the drying time is 120 - 240 minutes. The copper ion concentration in the dilute hydrochloric acid solution is controlled at ≤200 mg / L.

[0013] Specifically, after cleaning using the cleaning method of the present invention, the surface cleanliness and the purity of oxygen-free copper are greatly improved, meeting the usage requirements. Before cleaning, there are many types of impurity elements on the surface of the oxygen-free copper rod and the content of impurity elements is relatively high, while the weight content of copper is relatively low, being 74.95%. After cleaning, the surface cleanliness of the oxygen-free copper rod is significantly improved, the types of surface impurity elements are significantly reduced, and there is only oxygen element with a relatively low content, while the weight content of copper is relatively high, being 97.82%.

[0014] Specifically, in the cleaning method of the present invention, a process of cleaning with a dilute acid solution is added between the cleaning with the cleaning agent and the water washing. On the one hand, it ensures that copper ions are in an acidic solution, inhibits the hydrolysis of copper ions, and dissolves a large amount of copper ions on the surface of the material evenly in the dilute acid solution; on the other hand, it cools the material through the dilute acid solution, stabilizes the overall temperature of the material within a relatively low reasonable control range, and inhibits the oxidation of the material during the water washing process.

[0015] Specifically, when directly performing the water washing process after cleaning with the cleaning agent in the present invention, it is found that there are a large number of insoluble substances suspended in the aqueous solution. This is because solid insoluble substances generated by the hydrolysis of copper ions on the surface of the oxygen-free copper material are suspended. However, the dilute acid solution for pickling after cleaning with the cleaning agent is transparent, indicating that after the oxygen-free copper material is cleaned and dissolved by the dilute acid solution cleaning and dissolution scheme of the present invention, a better dissolution effect can be achieved, ensuring the cleaning efficiency of the oxygen-free copper. There are oxidation and copper hydrolysis deposition on the surface of the oxygen-free copper core rod without being cleaned by the dilute acid solution, and the cleaning effect is poor.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0017] (1) The cleaning agent provided by the present invention is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and water. The concentration of ammonium persulfate in the cleaning agent is 150 - 210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15 - 25 mL / L, the concentration of sodium chloride in the cleaning agent is 1.5 - 3.0 g / L, and water is used as the solvent. The persulfate ions in the cleaning agent solution undergo a strong oxidation-reduction reaction with copper, causing corrosion on the surface of the oxygen-free copper to achieve the cleaning purpose. After the ammonium persulfate solution acts on copper, it can ensure the surface microchemical state properties required before the assembly of the superconducting material, make the chemical properties of the material surface stable, and ensure anti-oxidation after cleaning. The concentration of ammonium persulfate provided by the present invention is moderate, ensuring the corrosion and cleaning ability of the cleaning agent, and also preventing salts from remaining on the surface of the oxygen-free copper due to saturation. The present invention controls the thickness of the corrosion layer on the surface of the oxygen-free copper by adjusting the concentration of each component, the solution temperature, and the cleaning time, ensuring that the required surface roughness of the oxygen-free copper material is obtained, and avoiding excessive, too small, or uneven surface roughness.

[0018] (2) Hydrochloric acid solution and sodium chloride are added to the cleaning agent of the present invention. Since the ammonium ions in ammonium persulfate hydrolyze to produce hydrogen ions, the solution shows acidity, but the acidity is relatively weak. To effectively inhibit the conversion of copper ions generated during the corrosion process into copper hydroxide precipitate and suspend in the solution, a certain amount of acid solution needs to be added. Through experiments, it is determined that adding hydrochloric acid has the best effect in the present invention. And ammonium persulfate will chemically react with the copper body but is difficult to react with the copper oxide scale. Adding a certain proportion of hydrochloric acid can ensure the rapid and uniform corrosion of the oxide scale, ensuring the stability and uniformity of the cleaning quality. The addition of inorganic acid makes the solution have a stronger polarity, and at the same time, the material specification structure is diverse. To ensure the uniformity of the corrosion of the microscopic state of the surface of oxygen-free copper materials and ensure the effective dissolution and exclusion of ions, a small amount of strong electrolyte sodium chloride is added to the solution to adjust the solution polarity and the solubility uniformity of the material surface, which can greatly improve the consistency of the corrosion state at different positions on the material surface.

[0019] (3) In the cleaning method of the present invention, a process of cleaning with dilute acid solution is added between the cleaning with the cleaning agent and the water washing. On the one hand, it ensures that copper ions are in an acidic solution, inhibits the hydrolysis of copper ions, and dissolves a large amount of copper ions on the surface of the material uniformly in the dilute acid solution; on the other hand, it cools the material through the dilute acid solution, making the overall temperature of the material stable within a reasonable and lower control range, inhibiting the oxidation of the material during the water washing process. In the dilute hydrochloric acid pickling process, oxygen-free copper will not be corroded and the material is safe. Under acidic conditions, it can also effectively inhibit the hydrolysis of copper ions generated during the corrosion process into copper hydroxide precipitate and deposit on the surface of the material. Therefore, the present invention further limits that the copper ion concentration in the dilute acid solution is lower than 200 mg / L, and the acidity is controlled at 0.5 - 2.0, maintaining a relatively high acidity to effectively avoid the hydrolysis of copper ions. The present invention uses pure water with a conductivity < 10 μs / cm as the solvent to prevent the complexity of the chemical properties of tap water from having a complex impact on the corrosion mechanism and the microscopic state of the material surface.

[0020] (4) After cleaning with the cleaning method of the present invention, the surface cleanliness and the purity of oxygen-free copper are greatly improved, meeting the usage requirements. Before cleaning, there are many types of impurity elements on the surface of the oxygen-free copper rod and the content of impurity elements is relatively high, while the weight content of copper is relatively low, being 74.95%. After cleaning, the surface cleanliness of the oxygen-free copper rod is significantly improved, the types of surface impurity elements are significantly reduced, only oxygen element remains and its content is relatively low, while the weight content of copper is relatively high, being 97.82%. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention.

[0022] Figure 1It is a 100 - fold SEM image of the oxygen - free copper sheath before cleaning.

[0023] Figure 2 It is a 100 - fold SEM image of the oxygen - free copper sheath after cleaning.

[0024] Figure 3 It is a 500 - fold SEM image of the oxygen - free copper sheath after cleaning.

[0025] Figure 4 It is a physical image of the oxygen - free copper sheath after cleaning.

[0026] Figure 5 It is a physical image of the oxygen - free copper core rod after cleaning.

[0027] Figure 6 It is a physical image of the dilute hydrochloric acid solution after cleaning the oxygen - free copper material in the dilute hydrochloric acid solution.

[0028] Figure 7 It is a physical image of the aqueous solution after washing the oxygen - free copper material with water.

[0029] Figure 8 It is a 500 - fold SEM image of the oxygen - free copper core rod with oxidation and copper ion hydrolysis deposition after cleaning.

[0030] Figure 9 It is a physical image of the oxygen - free copper core rod with oxidation and copper ion hydrolysis deposition after cleaning. Specific Embodiments

[0031] Next, the technical solutions of the present invention will be described in conjunction with the embodiments. However, the present invention is not limited to the following embodiments. In each embodiment, the experimental methods and detection methods are conventional methods unless otherwise specified; the reagents and materials can be obtained in the market unless otherwise specified.

[0032] Ammonium persulfate, hydrochloric acid, and sodium chloride are all of analytical purity;

[0033] The conductivity of pure water < 10 μs / cm.

[0034] The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and pure water. The concentration of ammonium persulfate in the cleaning agent is 150 - 210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15 - 25 mL / L, the concentration of sodium chloride in the cleaning agent is 1.5 - 3.0 g / L, and pure water is used as the solvent.

[0035] A cleaning method for oxygen - free copper used in superconducting materials specifically includes the following steps:

[0036] S1: First, add pure water into a corrosion-resistant tank (lined with fluoroplastics or PVC material), then slowly add hydrochloric acid and stir to dissolve the hydrochloric acid evenly. Subsequently, slowly add ammonium persulfate and stir evenly. Finally, slowly add sodium chloride and stir evenly to obtain a cleaning agent. The concentration of ammonium persulfate in the cleaning agent is 150 - 210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15 - 25 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.5 - 3.0 g / L.

[0037] S2: Control the temperature of the cleaning agent solution at 10 - 25 °C, immerse the oxygen-free copper material in the cleaning solution for 3 - 5 minutes, and control the thickness of the corrosion layer on the surface of the oxygen-free copper to be 15 - 25 μm.

[0038] S3: Transfer the oxygen-free copper material after the cleaning in S2 into a dilute hydrochloric acid solution with a pH of 0.5 - 2.0, a temperature of 10 - 20 °C, and a concentration of 1 - 4% for cleaning for 1 - 2 minutes, and then perform water washing and drying. The drying temperature is 55 - 65 °C, and the drying time is 120 - 240 minutes. The copper ion concentration in the dilute hydrochloric acid solution is controlled at ≤200 mg / L.

[0039] Example 1

[0040] This example provides a cleaning agent and a cleaning method for oxygen-free copper materials.

[0041] The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and pure water. The concentration of ammonium persulfate in the cleaning agent is 185 g / L, the concentration of hydrochloric acid in the cleaning agent is 18 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.8 g / L.

[0042] The cleaning method specifically includes the following steps:

[0043] S1: First, add 10 L of pure water into a corrosion-resistant tank lined with fluoroplastics, then slowly add 180 mL of hydrochloric acid and stir to dissolve the hydrochloric acid evenly. Subsequently, slowly add 1850 g of ammonium persulfate and stir evenly. Finally, slowly add 18 g of sodium chloride and stir evenly to obtain a cleaning agent.

[0044] S2: Control the temperature of the cleaning agent solution at 18 °C, immerse the oxygen-free copper sheath in the cleaning solution for 4 minutes, and control the thickness of the corrosion layer on the surface of the oxygen-free copper to be 18 μm.

[0045] S3: Transfer the oxygen-free copper sheath after the cleaning in S2 into a dilute hydrochloric acid solution with a pH of 0.8, a temperature of 16 °C, and a concentration of 2% for cleaning for 1.5 minutes, and then perform water washing and drying. The drying temperature is 55 °C, and the drying time is 240 minutes. The copper ion concentration in the dilute hydrochloric acid solution is controlled at ≤200 mg / L.

[0046] The elemental content results of the SEM-EDS detection on the surface of the oxygen-free copper sheath before and after cleaning are shown in Table 1 and Table 2. The SEM image at 100 times magnification of the oxygen-free copper sheath before cleaning is as shown in Figure 1 and the SEM image at 100 times magnification of the oxygen-free copper sheath after cleaning is as shown in Figure 2 The SEM image at 500 times magnification of the oxygen-free copper sheath after cleaning is as shown in Figure 3 and the physical picture of the oxygen-free copper sheath after cleaning is as shown in Figure 4 .

[0047] Table 1 Elemental content data of the SEM-EDS detection on the surface of the oxygen-free copper sheath before cleaning

[0048] Element Weight percentage / % Atomic percentage / % C K 15.32 42.36 N K 0.45 1.06 O K 6.83 14.17 Na K 1.81 2.61 Cl K 0.66 0.61 Cu K 74.95 39.18 Total 100.02 99.99

[0049] Table 2 Elemental content data of the SEM-EDS detection on the surface of the oxygen-free copper sheath after cleaning

[0050] Element Weight percentage / % Atomic percentage / % O K 2.18 8.13 Cu K 97.82 91.87 Total 100.00 100.00

[0051] From Table 1 and Figure 1 , it can be seen that before cleaning, the oxygen-free copper sheath has many types of impurity elements with high contents, and the weight content of copper is relatively low, at 74.95%. From Table 2 and Figure 2 , Figure 3 , it can be seen that after cleaning, the surface state of the oxygen-free copper sheath has changed, the cleanliness has been significantly improved, the types of surface impurity elements have been significantly reduced, and there is only oxygen element with a low content. After cleaning, the weight content of copper reaches 97.82%.

[0052] Example 2

[0053] This example provides a cleaning agent and a cleaning method for oxygen-free copper materials.

[0054] The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and pure water. The concentration of ammonium persulfate in the cleaning agent is 205 g / L, the concentration of hydrochloric acid in the cleaning agent is 22 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.8 g / L.

[0055] The cleaning method specifically includes the following steps:

[0056] S1: First add 10 L of pure water into a corrosion-resistant tank lined with PVC material, then slowly add 220 mL of hydrochloric acid and stir to dissolve the hydrochloric acid evenly. Subsequently, slowly add 2050 g of ammonium persulfate and stir evenly, and finally slowly add 18 g of sodium chloride and stir evenly to obtain the cleaning agent.

[0057] S2: Control the temperature of the cleaning agent solution at 22 °C, immerse the oxygen-free copper core rod in the cleaning solution for 3.5 min, and control the thickness of the corrosion layer on the surface of the oxygen-free copper at 20 μm.

[0058] S3: Transfer the oxygen-free copper sleeve after the cleaning in S2 into a dilute hydrochloric acid solution with a pH of 1.2, a temperature of 13°C, and a concentration of 3% for cleaning for 2 minutes within 30 seconds, and then perform water washing and drying. The drying temperature is 60°C, and the drying time is 180 minutes. The copper ion concentration in the dilute hydrochloric acid solution is controlled at ≤200 mg / L.

[0059] The physical picture of the oxygen-free copper core rod after cleaning is as Figure 5 shown, and the state of the dilute hydrochloric acid solution after cleaning with the dilute hydrochloric acid solution in S3 is as Figure 6 shown. From Figure 5 it can be seen that the surface of the oxygen-free copper core rod cleaned by the cleaning method of the present invention is bright, uniform, natural-colored, and there are no acid marks or water marks, etc. The surface protection ability is strong, the cleaning quality is good, and the requirements of the superconducting material for the surface state of the oxygen-free copper are met. From Figure 6 it can be seen that after cleaning with the dilute acid solution, the dilute acid solution is transparent and there are no insoluble solids of copper ion hydrolysis.

[0060] Example 3

[0061] This example provides a cleaning agent and a cleaning method for oxygen-free copper materials.

[0062] The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and pure water. The concentration of ammonium persulfate in the cleaning agent is 210 g / L, the concentration of hydrochloric acid in the cleaning agent is 25 mL / L, and the concentration of sodium chloride in the cleaning agent is 3.0 g / L.

[0063] The cleaning method specifically includes the following steps:

[0064] S1: First add 10 L of pure water into a corrosion-resistant tank lined with PVC material, then slowly add 250 mL of hydrochloric acid and stir to dissolve the hydrochloric acid evenly, then slowly add 2100 g of ammonium persulfate and stir evenly, and finally slowly add 30 g of sodium chloride and stir evenly to obtain the cleaning agent.

[0065] S2: Control the temperature of the cleaning agent solution at 25°C, immerse the oxygen-free copper core rod in the cleaning solution for cleaning for 5 minutes, and control the thickness of the corrosion layer on the surface of the oxygen-free copper at 25 μm.

[0066] S3: Transfer the oxygen-free copper sleeve after the cleaning in S2 into a dilute hydrochloric acid solution with a pH of 1.0, a temperature of 20°C, and a concentration of 4% for cleaning for 1.5 minutes within 30 seconds, and then perform water washing and drying. The drying temperature is 60°C, and the drying time is 140 minutes. The copper ion concentration in the dilute hydrochloric acid solution is controlled at ≤200 mg / L.

[0067] The surface of the oxygen-free copper core rod cleaned by the cleaning method of this example is bright, uniform, natural-colored, and there are no acid marks or water marks, etc. The surface protection ability is strong, the cleaning quality is good, and the requirements of the superconducting material for the surface state of the oxygen-free copper are met.

[0068] Example 4

[0069] This example provides a cleaning agent and a cleaning method for oxygen-free copper materials.

[0070] The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride, and pure water. The concentration of ammonium persulfate in the cleaning agent is 205 g / L, the concentration of hydrochloric acid in the cleaning agent is 22 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.8 g / L.

[0071] The cleaning method specifically includes the following steps:

[0072] S1: First, add 10 L of pure water into a corrosion-resistant tank lined with PVC material, then slowly add 220 mL of hydrochloric acid and stir to dissolve the hydrochloric acid evenly. Subsequently, slowly add 2050 g of ammonium persulfate and stir evenly. Finally, slowly add 18 g of sodium chloride and stir evenly to obtain the cleaning agent.

[0073] S2: Control the temperature of the cleaning agent solution at 10 °C, immerse the oxygen-free copper core rod in the cleaning solution for 3 min, and control the thickness of the corrosion layer on the surface of the oxygen-free copper to 15 μm.

[0074] S3: Transfer the oxygen-free copper sheath after the cleaning in S2 into a dilute hydrochloric acid solution with a pH of 0.7, a temperature of 22 °C, and a concentration of 3% within 30 s and clean for 2 min. Subsequently, perform water washing and drying. The drying temperature is 65 °C, and the drying time is 120 min. The copper ion concentration in the dilute hydrochloric acid solution is controlled at ≤200 mg / L.

[0075] After being cleaned by the cleaning method of the present invention, the surface of the oxygen-free copper core rod is bright, uniform, natural in color, and free of acid marks and water marks. The surface protection ability is strong, and the cleaning quality is good, meeting the requirements of the superconducting material for the surface state of oxygen-free copper.

[0076] Comparative Example 1

[0077] The cleaning agent and the cleaning method are the same as those in Example 1, except that in S3, water washing and drying are directly carried out without cleaning with the dilute acid solution. The state of the water washing solution after water washing is as Figure 7 shown, the 500-fold morphology diagram of the scanning electron microscope of the oxygen-free copper core rod after cleaning is as Figure 8 shown, and the physical diagram of the oxygen-free copper core rod after cleaning is as Figure 9 shown.

[0078] From Figure 7It can be seen that when directly entering water washing after being cleaned by the cleaning agent, a large amount of insoluble substances are suspended in the aqueous solution. Since solid insoluble substances are suspended due to the hydrolysis of copper ions on the surface of the oxygen-free copper material, and the dilute acid solution for pickling after being cleaned by the cleaning agent is transparent, it indicates that after being cleaned and dissolved by the dilute acid solution of the present invention, the oxygen-free copper material can achieve a good dissolution effect and ensure the cleaning efficiency of the oxygen-free copper. From Figure 8 and Figure 9 it can be seen that oxidation and copper hydrolysis deposition exist on the surface of the oxygen-free copper core rod without being cleaned by the dilute acid solution, and the cleaning effect is poor.

[0079] The above-described embodiments are part of the embodiments of the present invention, rather than all embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the present invention claimed, but merely represents the selected embodiments of the present invention. All other embodiments obtained by relevant deductions and substitutions made by those of ordinary skill in the art under the condition of the inventive concept of the present invention without creative efforts belong to the scope of protection of the present invention.

Claims

1. A cleaning agent for oxygen-free copper for superconducting materials, characterized in that: The cleaning agent is composed of ammonium persulfate, hydrochloric acid, sodium chloride and water; The concentration of ammonium persulfate in the cleaning agent is 150-210 g / L, the concentration of hydrochloric acid in the cleaning agent is 15-25 mL / L, and the concentration of sodium chloride in the cleaning agent is 1.5-3.0 g / L.

2. A method for cleaning oxygen-free copper for superconducting materials, characterized in that: Use the cleaning agent according to claim 1.

3. The cleaning method according to claim 2, characterized in that: The use temperature of the cleaning agent is 10-25° C., and the cleaning time of the cleaning agent is 3-5 minutes.

4. The cleaning method according to claim 2, characterized in that: After cleaning with the cleaning agent, the corrosion layer thickness on the surface of the oxygen-free copper material is 15 to 25 μm.

5. The cleaning method according to claim 2, characterized in that: After cleaning with the cleaning agent, pickling is performed using a dilute acid solution; The dilute acid solution is a dilute hydrochloric acid solution, and the dilute hydrochloric acid solution is a hydrochloric acid solution with a concentration of 1 to 4%.

6. The cleaning method according to claim 5, characterized in that: The pickling temperature is 10-20° C., and the pickling time is 1-2 min.

7. The cleaning method according to claim 5, characterized in that: The copper ion concentration in the dilute hydrochloric acid solution is ≤200 mg / L.

8. The cleaning method according to claim 5, characterized in that: After cleaning with the cleaning agent, use a dilute acid solution for pickling within 30 seconds.

9. The cleaning method according to claim 5, characterized in that: The acid washing is followed by water washing and drying.

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