A process for producing oxygen-free copper

Abstract

This invention discloses a process for producing oxygen-free copper, relating to the field of metallurgical technology, comprising the following steps: Step S1, raw material pretreatment; Step S2, preparation of electrolytic copper; Step S3, pretreatment of electrolytic copper; Step S4, vacuum melting and microwave-assisted melting; Step S5, refining, solidification casting; Step S6, post-treatment. The oxygen-free copper produced by this process has high purity, low and stable oxygen content, and excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to a process for producing oxygen-free copper. Background Technology

[0002] In modern electronics, power transmission, and other fields, oxygen-free copper is widely used in information, electronics, power, automotive, refrigeration, and military industries due to its high purity, high conductivity, low oxygen content, good processing performance, and excellent corrosion resistance. With continuous advancements in industrial technology, international and domestic requirements for oxygen-free copper are becoming increasingly stringent, particularly regarding its oxygen content and purity.

[0003] Traditional oxygen-free copper production processes suffer from drawbacks such as high investment and energy consumption, low yield and production efficiency, unstable oxygen content, poor surface quality, high internal porosity, coarse columnar crystal structure, poor physical and mechanical properties, and low product quality. Commercially available oxygen-free copper also exhibits various technical defects, including high impurity content, difficulty in controlling oxygen content, uneven microstructure, low production efficiency, and unstable quality.

[0004] To address the aforementioned technical problems, Chinese invention patent CN110029239B discloses an oxygen-free copper production process, comprising the following steps: cleaning the slag from the walls of the melting furnace and holding furnace; adding copper material to the melting furnace and melting it into molten copper; introducing the molten copper from the melting furnace into the holding furnace; heating both the holding furnace and the melting furnace to 1180-1250℃ for burn-off; subsequently covering the surfaces of both the molten copper in the holding furnace and the melting furnace with a layer of charcoal powder and graphite powder; and cooling the melting furnace to 1150℃. The temperature is initially set at -1200℃, then the holding furnace is cooled to 1140-1175℃. Carbon rods are inserted into the molten copper in both the melting furnace and the holding furnace to accelerate deoxygenation. Both furnaces are kept at the same temperature. When the phosphorus content drops below 10 ppm, copper ingot production begins. The oxygen content of the ingots is checked. If the oxygen content is not less than 10 ppm, the molten copper is covered and kept warm for further deoxygenation. If the oxygen content is less than 10 ppm, the carbon rods are removed from the melting furnace, an electrolytic plate is added, the carbon rods in the holding furnace are replaced, and copper ingot production continues. This method produces oxygen-free copper with a shorter production cycle and saves on production costs. However, the purity and mechanical properties of this oxygen-free copper need further improvement, and the oxygen content needs further reduction.

[0005] It is evident that there is a need to seek a simpler and more effective production process to produce oxygen-free copper with high purity, low and stable oxygen content, and excellent mechanical properties. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a process for producing oxygen-free copper with high purity, low and stable oxygen content, and excellent mechanical properties.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: an oxygen-free copper production process, comprising the following steps:

[0008] Step S1, Raw material pretreatment: After chemical polishing and hydrophilic treatment, the high-purity copper sheet is sputtered in a magnetron sputtering equipment with a high-purity copper target under an argon atmosphere to form a uniform copper seed crystal layer; the crude copper is then subjected to ultrasonic-plasma combined cleaning.

[0009] Step S2, Preparation of Electrolytic Copper: Using crude copper treated in step S1 as the anode and high-purity copper sheet treated in step S1 as the cathode, electrolysis is performed using a square wave pulsed current to obtain electrolytic copper. The electrolyte used is deionized water as the solvent and includes the following components at the following concentrations: copper sulfate pentahydrate 150-200 g / L, sulfuric acid 110-140 g / L, hydroxyethyl hexahydrotriazine 6-10 mg / L, glyceryl phosphorylcholine 1-4 mg / L, surfactant 0.3-0.8 g / L, tea polyphenols 1-3 mg / L, adenosine 0.1-3 mg / L, and disodium ethylenediaminetetraacetate 0.1-0.8 g / L.

[0010] Step S3, Pretreatment of electrolytic copper: Crush the electrolytic copper into small pieces, place them in an ultrasonic cleaner, add a 1-5% (w / w) dilute sulfuric acid solution, and soak for 15-22 minutes at an ultrasonic frequency of 40kHz and a power of 300W; then rinse with deionized water until neutral, and finally dry in a constant temperature drying oven at 80-90℃ for 3-4 hours.

[0011] Step S4, Vacuum Melting and Microwave Assistance: Place the pretreated electrolytic copper into a vacuum induction melting furnace, evacuate and continuously introduce high-purity helium to remove oxygen. When the set vacuum degree is reached, heat to 1200-1240℃ at a heating rate of 6-10℃ / min and hold for 10-15min for melting. During the melting process, cover the surface of the copper liquid with flake graphite and introduce high-purity helium for protection. The helium flow rate is controlled at 3-5L / min. At the same time, microwave assistance is used for 10-15min.

[0012] Step S5, Refining, Solidification and Casting: After the temperature of the molten copper is stabilized, add the refining agent and stir electromagnetically for 10-13 minutes. Simultaneously insert an ultrasonic probe and an electromagnetic coil into the molten copper for ultrasonic-electromagnetic synergistic treatment. Remove the slag and filter the solution using a ceramic filter. Pour the filtrate into a graphite mold preheated to 300-320℃. Use directional solidification technology and set a cooling device at the bottom of the mold. Control the cooling rate at 45-55℃ / s so that the molten copper solidifies from the bottom up to obtain oxygen-free copper ingots.

[0013] Step S6, Post-processing: The oxygen-free copper ingot is subjected to heat treatment and hot rolling in sequence to obtain oxygen-free copper.

[0014] Preferably, the power of sputtering in step S1 is 150-200W and the deposition time is 10-15 minutes.

[0015] Preferably, the ultrasonic-plasma combined cleaning in step S1 specifically involves: first, the crude copper is placed in an ultrasonic cleaning tank, where it is subjected to 40kHz high-frequency ultrasonic waves and an alkaline cleaning agent to remove surface oil and loose impurities; then, it is placed in a low-temperature plasma treatment chamber, where argon plasma bombardment is used to remove stubborn oxides and residual impurities, so that the surface cleanliness of the crude copper reaches Ra≤0.8μm.

[0016] Preferably, the forward current density of the square wave pulse current in step S2 is 300-350 A / m. 2 The pulse frequency is 500-1000Hz, the duty cycle is 60%-70%, and the negative current density is 100-160A / m. 2 Within each pulse cycle, the forward current promotes copper ion deposition, while the reverse current eliminates concentration polarization on the electrode surface, improving the quality of copper crystallization at the cathode.

[0017] Preferably, the electrolysis temperature in step S2 is 50-60°C.

[0018] Preferably, the surfactant in step S2 is a mixture of sodium dodecylbenzenesulfonate and polyethylene glycol 400 in a mass ratio of 1:(1-2).

[0019] Preferably, the purity of the high-purity helium gas in step S4 is not less than 99.999%.

[0020] Preferably, the vacuum degree set in step S4 is (1-2)×10⁻⁶. -5 Pa.

[0021] Preferably, the thickness of the flake graphite in step S4 is 90-110 mm.

[0022] Preferably, the microwave frequency in step S4 is 2.0-2.8 GHz and the power is 1000-2000 W.

[0023] Preferably, the mass ratio of copper liquid to refining agent in step S5 is 100:(0.005-0.01).

[0024] Preferably, the refining agent in step S5 comprises the following components by weight: 0.8-1.2 parts boron, 0.5-0.8 parts zirconium, 2-4 parts titanium, 3-5 parts aluminum, 1-2 parts yttrium, 3-5 parts sodium fluorosilicate, and 4-6 parts calcium fluoride.

[0025] Preferably, in step S5, the ultrasonic frequency of the ultrasonic-electromagnetic synergistic treatment is 40-80kHz, the power is 200-400W, the magnetic field strength generated by the electromagnetic coil is 0.5T, and the processing time is 15-20 minutes.

[0026] Preferably, the heat treatment temperature in step S6 is 600-620℃, and the holding time is 1-1.5h.

[0027] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0028] (1) The oxygen-free copper production process disclosed in this invention has a short process flow, fast speed, low energy consumption, low dependence on equipment, high preparation efficiency and yield, and is suitable for continuous large-scale production. It has high promotion and application value.

[0029] (2) The oxygen-free copper production process disclosed in this invention utilizes magnetron sputtering to deposit a nanoscale copper seed layer on the cathode during the raw material pretreatment stage, providing a large number of active sites for copper ion deposition and significantly improving the nucleation and growth rate; it employs ultrasonic-plasma combined cleaning, combining ultrasonic waves and low-temperature plasma to efficiently remove various impurities from the surface of crude copper, effectively improving the cleanliness of the crude copper surface and providing better conditions for the subsequent electrolytic copper purification process; it uses pulsed current electrolysis to optimize copper ion deposition and eliminate concentration polarization by alternating forward and reverse currents.

[0030] (3) The production process of oxygen-free copper disclosed in this invention uses deionized water as the electrolyte, which includes the following components at the following concentrations: copper sulfate pentahydrate 150-200 g / L, sulfuric acid 110-140 g / L, hydroxyethyl hexahydrotriazine 6-10 mg / L, glyceryl phosphorylcholine 1-4 mg / L, surfactant 0.3-0.8 g / L, tea polyphenols 1-3 mg / L, adenosine 0.1-3 mg / L, and disodium ethylenediaminetetraacetate 0.1-0.8 g / L. Through the mutual cooperation and synergistic effect of the components, the electrolyte has good stability, and the electrolytic copper obtained by electrolysis using it has low impurity content, high purity, low oxygen content and stability. Glycerylphosphocholine molecules possess certain polarity and surface activity, enabling them to adsorb onto the cathode surface. This helps regulate the deposition rate and uniformity of copper ions on the cathode surface, resulting in more orderly copper ion deposition, thus refining copper grains, increasing the density and surface smoothness of the cathode copper, and improving its physical properties and appearance quality. It can also participate in the charge transfer process on the electrode surface, playing a catalytic or promoting role in the reduction reaction of copper ions, lowering the activation energy of the reaction, and allowing copper ions to be efficiently reduced and deposited at lower overpotentials, thus improving electrolysis efficiency and reducing energy consumption. Glycerylphosphocholine can interact with certain impurity ions in the electrolyte to form stable complexes or adsorption layers, thereby reducing the activity of impurity ions on the cathode surface, inhibiting the co-deposition of impurity ions with copper ions, and improving the purity of the cathode copper. Glycerylphosphocholine also possesses certain antioxidant and complexing capabilities, reacting with some unstable components or impurities in the electrolyte, reducing their adverse effects on electrolyte performance, improving electrolyte stability and service life, reducing the frequency of electrolyte replacement due to deterioration, and lowering production costs. Tea polyphenols possess strong antioxidant properties, preventing excessive oxidation of metal ions in the electrolyte and avoiding the formation of high-valence metal ion impurities. This helps maintain the stability of the valence state of metal ions in the electrolyte, ensuring the normal progress of the electrolysis reaction. Tea polyphenol molecules have certain surface activity, allowing them to adsorb onto the electrode surface, altering its wettability, improving contact between the electrolyte and the electrode, promoting uniform deposition of copper ions on the cathode surface, and increasing the smoothness and density of the cathode copper. They can also undergo complexation reactions with certain impurity ions in the electrolyte, fixing these ions and reducing their likelihood of discharge at the cathode, thereby improving the purity of the cathode copper. Adenosine molecules have a specific chemical structure and electron cloud distribution, allowing them to participate in charge transfer processes on the electrode surface. As an electron transfer intermediate, they lower the activation energy of the copper ion reduction reaction, thus accelerating the rate at which copper ions gain electrons and deposit on the cathode surface, improving electrolysis efficiency. Adenosine can adsorb onto the cathode surface, forming an ordered molecular film.This film guides the deposition of copper ions, allowing them to deposit more uniformly on the cathode surface. This refines the copper grains, improving the density, hardness, and toughness of the cathode copper. It also improves surface smoothness, reduces surface defects, and enhances product quality and appearance. Electrolytes typically contain impurity ions such as iron and zinc, which can deposit alongside copper ions at the cathode, affecting its purity. Adenosine complexes with these impurity ions, forming stable complexes. The presence of these complexes reduces the activity of impurity ions on the cathode surface, making them less likely to deposit during cathode discharge, thus improving the purity of the cathode copper.

[0031] (4) The oxygen-free copper production process disclosed in this invention adopts ultrasonic enhanced cleaning in the pretreatment stage of electrolytic copper, vacuum melting combined with microwave assistance and high-purity helium protection, adding refining agent and electromagnetic stirring, ultrasonic-electromagnetic synergistic treatment, and multiple measures working together to make the final product have higher copper purity, lower impurity content, and lower oxygen content, resulting in higher mechanical properties of the oxygen-free copper. The application of ultrasonic-electromagnetic synergistic treatment and directional solidification casting technology enables the copper liquid to achieve directional growth during solidification, reducing segregation. The oxygen-free copper ingot obtained has a uniform structure and fine grains, which improves the mechanical and processing performance of the product.

[0032] (5) The oxygen-free copper production process disclosed in this invention comprises the following components by weight: boron 0.8-1.2 parts, zirconium 0.5-0.8 parts, titanium 2-4 parts, aluminum 3-5 parts, yttrium 1-2 parts, sodium fluorosilicate 3-5 parts, and calcium fluoride 4-6 parts. Through the combined action of the components of the refining agent, further deoxidation and impurity removal can be achieved, improving the microstructure and properties, which is beneficial to the improvement of product quality. Detailed Implementation

[0033] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0034] Example 1

[0035] A process for producing oxygen-free copper includes the following steps:

[0036] Step S1, Raw material pretreatment: After chemical polishing and hydrophilic treatment, the high-purity copper sheet is sputtered in a magnetron sputtering equipment with a high-purity copper target under an argon atmosphere to form a uniform copper seed crystal layer; the crude copper is then subjected to ultrasonic-plasma combined cleaning.

[0037] Step S2, Preparation of Electrolytic Copper: Using crude copper treated in step S1 as the anode and high-purity copper sheet treated in step S1 as the cathode, electrolysis is performed using a square wave pulsed current to obtain electrolytic copper. The electrolyte used is deionized water as the solvent and includes the following components at the following concentrations: copper sulfate pentahydrate 150 g / L, sulfuric acid 110 g / L, hydroxyethyl hexahydrotriazine 6 mg / L, glyceryl phosphorylcholine 1 mg / L, surfactant 0.3 g / L, tea polyphenols 1 mg / L, adenosine 0.1 mg / L, and disodium ethylenediaminetetraacetate 0.1 g / L.

[0038] Step S3, Pretreatment of electrolytic copper: Crush the electrolytic copper into small pieces, place them in an ultrasonic cleaner, add a 1% (w / w) dilute sulfuric acid solution, and soak for 15 minutes at an ultrasonic frequency of 40kHz and a power of 300W; then rinse with deionized water until neutral, and finally dry in a constant temperature drying oven at 80℃ for 3 hours.

[0039] Step S4, Vacuum Melting and Microwave Assistance: Place the pretreated electrolytic copper into a vacuum induction melting furnace, evacuate and continuously introduce high-purity helium to remove oxygen. When the set vacuum degree is reached, heat to 1200℃ at a heating rate of 6℃ / min and hold for 10min for melting. During the melting process, cover the surface of the copper liquid with flake graphite and introduce high-purity helium for protection. The helium flow rate is controlled at 3L / min. At the same time, microwave assistance is used for 10min.

[0040] Step S5, Refining, Solidification and Casting: After the temperature of the copper liquid is stabilized, add refining agent and stir electromagnetically for 10 minutes. Insert an ultrasonic probe and an electromagnetic coil into the copper liquid at the same time for ultrasonic-electromagnetic synergistic treatment. Remove slag and filter with a ceramic filter. Pour the filtrate into a graphite mold preheated to 300°C. Use directional solidification technology and set a cooling device at the bottom of the mold. Control the cooling rate at 45°C / s so that the copper liquid solidifies from the bottom up to obtain oxygen-free copper ingots.

[0041] Step S6, Post-processing: The oxygen-free copper ingot is subjected to heat treatment and hot rolling in sequence to obtain oxygen-free copper.

[0042] The sputtering coating power in step S1 is 150W, and the deposition time is 10 minutes. The ultrasonic-plasma combined cleaning in step S1 is as follows: the crude copper is first put into an ultrasonic cleaning tank, and under the action of 40kHz high-frequency ultrasonic waves, alkaline cleaning agent is used to remove surface oil and loose impurities. Then it enters a low-temperature plasma treatment chamber, and argon plasma is used to bombard the surface to remove stubborn oxides and residual impurities, so that the surface cleanliness of the crude copper reaches Ra≤0.8μm.

[0043] The forward current density of the square wave pulse current in step S2 is 300 A / m. 2The pulse frequency is 500Hz, the duty cycle is 60%, and the negative current density is 100A / m. 2 Within each pulse cycle, the forward current promotes copper ion deposition, while the reverse current eliminates concentration polarization on the electrode surface, improving the quality of copper crystallization at the cathode. The electrolysis temperature in step S2 is 50°C.

[0044] The surfactant mentioned in step S2 is a mixture of sodium dodecylbenzenesulfonate and polyethylene glycol 400 in a mass ratio of 1:1; the purity of the high-purity helium gas mentioned in step S4 is not less than 99.999%; the vacuum degree set in step S4 is 1×10⁻⁶. -5 Pa; the thickness of the flake graphite in step S4 is 90 mm; the frequency of the microwave in step S4 is 2.0 GHz and the power is 1000 W.

[0045] The mass ratio of copper liquid to refining agent in step S5 is 100:0.005; the refining agent in step S5 includes the following components by weight: 0.8 parts boron, 0.5 parts zirconium, 2 parts titanium, 3 parts aluminum, 1 part yttrium, 3 parts sodium fluorosilicate, and 4 parts calcium fluoride; the ultrasonic-electromagnetic synergistic treatment in step S5 has an ultrasonic frequency of 40 kHz, a power of 200 W, a magnetic field strength of 0.5 T generated by the electromagnetic coil, and a treatment time of 15 minutes; the heat treatment temperature in step S6 is 600℃, and the holding time is 1 hour.

[0046] Example 2

[0047] A process for producing oxygen-free copper includes the following steps:

[0048] Step S1, Raw material pretreatment: After chemical polishing and hydrophilic treatment, the high-purity copper sheet is sputtered in a magnetron sputtering equipment with a high-purity copper target under an argon atmosphere to form a uniform copper seed crystal layer; the crude copper is then subjected to ultrasonic-plasma combined cleaning.

[0049] Step S2, Preparation of Electrolytic Copper: Using crude copper treated in step S1 as the anode and high-purity copper sheet treated in step S1 as the cathode, electrolysis is performed using a square wave pulsed current to obtain electrolytic copper. The electrolyte used is deionized water as the solvent and includes the following components at the following concentrations: copper sulfate pentahydrate 160 g / L, sulfuric acid 120 g / L, hydroxyethyl hexahydrotriazine 7 mg / L, glycerol phosphorylcholine 2 mg / L, surfactant 0.4 g / L, tea polyphenols 1.5 mg / L, adenosine 1 mg / L, and disodium ethylenediaminetetraacetate 0.2 g / L.

[0050] Step S3, Pretreatment of electrolytic copper: Crush the electrolytic copper into small pieces, place them in an ultrasonic cleaner, add a 2% (w / w) dilute sulfuric acid solution, and soak for 17 minutes at an ultrasonic frequency of 40kHz and a power of 300W; then rinse with deionized water until neutral, and finally dry in a constant temperature drying oven at 83℃ for 3.2 hours.

[0051] Step S4, Vacuum Melting and Microwave Assistance: Place the pretreated electrolytic copper into a vacuum induction melting furnace, evacuate and continuously introduce high-purity helium to remove oxygen. When the set vacuum degree is reached, heat to 1210℃ at a heating rate of 7℃ / min and hold for 12min for melting. During the melting process, cover the surface of the copper liquid with flake graphite and introduce high-purity helium for protection. The helium flow rate is controlled at 3.5L / min. At the same time, microwave assistance is used for 12min.

[0052] Step S5, Refining, Solidification and Casting: After the temperature of the copper liquid stabilizes, add refining agent and stir electromagnetically for 11 minutes. Simultaneously insert an ultrasonic probe and an electromagnetic coil into the copper liquid for ultrasonic-electromagnetic synergistic treatment. Remove slag, filter using a ceramic filter, and pour the filtrate into a graphite mold preheated to 305°C. Use directional solidification technology, with a cooling device at the bottom of the mold and a cooling rate controlled at 48°C / s, so that the copper liquid solidifies from the bottom up to obtain oxygen-free copper ingots.

[0053] Step S6, Post-processing: The oxygen-free copper ingot is subjected to heat treatment and hot rolling in sequence to obtain oxygen-free copper.

[0054] The sputtering coating power in step S1 is 160W, and the deposition time is 12 minutes. The ultrasonic-plasma combined cleaning in step S1 is as follows: the crude copper is first put into an ultrasonic cleaning tank, and under the action of 40kHz high-frequency ultrasonic waves, alkaline cleaning agent is used to remove surface oil and loose impurities. Then it enters a low-temperature plasma treatment chamber, and argon plasma bombardment is used to remove stubborn oxides and residual impurities, so that the surface cleanliness of the crude copper reaches Ra≤0.8μm.

[0055] The forward current density of the square wave pulse current in step S2 is 320 A / m. 2 The pulse frequency is 700Hz, the duty cycle is 63%, and the negative current density is 120A / m. 2 Within each pulse cycle, the forward current promotes copper ion deposition, while the reverse current eliminates concentration polarization on the electrode surface, improving the quality of copper crystallization at the cathode. The electrolysis temperature in step S2 is 53°C. The surfactant in step S2 is a mixture of sodium dodecylbenzenesulfonate and polyethylene glycol 400 in a mass ratio of 1:1.3.

[0056] The purity of the high-purity helium gas mentioned in step S4 is not less than 99.999%; the vacuum level set in step S4 is 1.3 × 10⁻⁶.-5 Pa; the thickness of the flake graphite in step S4 is 95 mm; the frequency of the microwave in step S4 is 2.2 GHz and the power is 1300 W; the mass ratio of copper liquid to refining agent in step S5 is 100:0.007; the refining agent in step S5 includes the following components by weight: boron 0.9 parts, zirconium 0.6 parts, titanium 2.5 parts, aluminum 3.5 parts, yttrium 1.2 parts, sodium fluorosilicate 3.5 parts, calcium fluoride 4.5 parts; the ultrasonic frequency of the ultrasonic-electromagnetic synergistic treatment in step S5 is 50 kHz, the power is 250 W, the magnetic field strength generated by the electromagnetic coil is 0.5 T, and the treatment time is 17 minutes; the temperature of the heat treatment in step S6 is 605℃, and the holding time is 1 h.

[0057] Example 3

[0058] A process for producing oxygen-free copper includes the following steps:

[0059] Step S1, Raw material pretreatment: After chemical polishing and hydrophilic treatment, the high-purity copper sheet is sputtered in a magnetron sputtering equipment with a high-purity copper target under an argon atmosphere to form a uniform copper seed crystal layer; the crude copper is then subjected to ultrasonic-plasma combined cleaning.

[0060] Step S2, Preparation of Electrolytic Copper: Using crude copper treated in step S1 as the anode and high-purity copper sheet treated in step S1 as the cathode, electrolysis is performed using a square wave pulsed current to obtain electrolytic copper. The electrolyte used is deionized water as the solvent and includes the following components at the following concentrations: copper sulfate pentahydrate 180 g / L, sulfuric acid 125 g / L, hydroxyethyl hexahydrotriazine 8 mg / L, glyceryl phosphorylcholine 2.5 mg / L, surfactant 0.6 g / L, tea polyphenols 2 mg / L, adenosine 1.5 mg / L, and disodium ethylenediaminetetraacetate 0.5 g / L.

[0061] Step S3, Pretreatment of electrolytic copper: Crush the electrolytic copper into small pieces, place them in an ultrasonic cleaner, add a 3.5% dilute sulfuric acid solution, and soak for 19 minutes at an ultrasonic frequency of 40kHz and a power of 300W; then rinse with deionized water until neutral, and finally dry in a constant temperature drying oven at 85℃ for 3.5 hours.

[0062] Step S4, Vacuum Melting and Microwave Assistance: Place the pretreated electrolytic copper into a vacuum induction melting furnace, evacuate and continuously introduce high-purity helium to remove oxygen. When the set vacuum degree is reached, heat to 1220℃ at a heating rate of 8℃ / min and hold for 13min for melting. During the melting process, cover the surface of the copper liquid with flake graphite and introduce high-purity helium for protection. The helium flow rate is controlled at 4L / min. At the same time, microwave assistance is used for 13min.

[0063] Step S5, refining, solidification and casting: After the temperature of the copper liquid is stabilized, add refining agent and stir electromagnetically for 12 minutes. Insert an ultrasonic probe and an electromagnetic coil into the copper liquid at the same time to perform ultrasonic-electromagnetic synergistic treatment. Remove slag and filter with a ceramic filter. Pour the filtrate into a graphite mold preheated to 310°C. Use directional solidification technology and set a cooling device at the bottom of the mold. Control the cooling rate at 50°C / s so that the copper liquid solidifies from the bottom up to obtain oxygen-free copper ingots.

[0064] Step S6, Post-processing: The oxygen-free copper ingot is subjected to heat treatment and hot rolling in sequence to obtain oxygen-free copper.

[0065] The sputtering deposition power in step S1 is 180W, and the deposition time is 13 minutes. The ultrasonic-plasma combined cleaning in step S1 specifically involves: first, the crude copper is placed in an ultrasonic cleaning tank, where it is subjected to 40kHz high-frequency ultrasound in conjunction with an alkaline cleaning agent to remove surface oil and loose impurities; then, it enters a low-temperature plasma treatment chamber, where argon plasma bombardment removes stubborn oxides and residual impurities, achieving a surface cleanliness of Ra≤0.8μm for the crude copper. The forward current density of the square wave pulse current in step S2 is 330A / m. 2 The pulse frequency is 800Hz, the duty cycle is 65%, and the negative current density is 130A / m. 2 Within each pulse cycle, the forward current promotes copper ion deposition, while the reverse current eliminates concentration polarization on the electrode surface, improving the quality of copper crystallization at the cathode. The electrolysis temperature in step S2 is 55°C. The surfactant in step S2 is a mixture of sodium dodecylbenzenesulfonate and polyethylene glycol 400 in a mass ratio of 1:1.5.

[0066] The purity of the high-purity helium gas mentioned in step S4 is not less than 99.999%; the vacuum level set in step S4 is 1.5 × 10⁻⁶. -5 Pa; the thickness of the flake graphite in step S4 is 100 mm; the frequency of the microwave in step S4 is 2.5 GHz and the power is 1500 W; the mass ratio of copper liquid to refining agent in step S5 is 100:0.008; the refining agent in step S5 includes the following components by weight: 1 part boron, 0.65 parts zirconium, 3 parts titanium, 4 parts aluminum, 1.5 parts yttrium, 4 parts sodium fluorosilicate, and 5 parts calcium fluoride; the ultrasonic frequency of the ultrasonic-electromagnetic synergistic treatment in step S5 is 60 kHz, the power is 300 W, the magnetic field strength generated by the electromagnetic coil is 0.5 T, and the treatment time is 18 minutes; the temperature of the heat treatment in step S6 is 610 °C, and the holding time is 1 h.

[0067] Example 4

[0068] A process for producing oxygen-free copper includes the following steps:

[0069] Step S1, Raw material pretreatment: After chemical polishing and hydrophilic treatment, the high-purity copper sheet is sputtered in a magnetron sputtering equipment with a high-purity copper target under an argon atmosphere to form a uniform copper seed crystal layer; the crude copper is then subjected to ultrasonic-plasma combined cleaning.

[0070] Step S2, Preparation of Electrolytic Copper: Using crude copper treated in step S1 as the anode and high-purity copper sheet treated in step S1 as the cathode, electrolysis is performed using a square wave pulse current to obtain electrolytic copper. The electrolyte used is deionized water as the solvent and includes the following components at the following concentrations: copper sulfate pentahydrate 190 g / L, sulfuric acid 135 g / L, hydroxyethyl hexahydrotriazine 9.5 mg / L, glycerol phosphorylcholine 3.5 mg / L, surfactant 0.7 g / L, tea polyphenols 2.5 mg / L, adenosine 2.5 mg / L, and disodium ethylenediaminetetraacetate 0.7 g / L.

[0071] Step S3, Pretreatment of electrolytic copper: The electrolytic copper is broken into small pieces, placed in an ultrasonic cleaner, and a 4% (w / w) dilute sulfuric acid solution is added. The mixture is then soaked for 21 minutes at an ultrasonic frequency of 40kHz and a power of 300W. After that, it is rinsed with deionized water until neutral, and finally dried in a constant temperature drying oven at 88℃ for 3.8 hours.

[0072] Step S4, Vacuum Melting and Microwave Assistance: Place the pretreated electrolytic copper into a vacuum induction melting furnace, evacuate and continuously introduce high-purity helium to remove oxygen. When the set vacuum degree is reached, heat to 1235℃ at a heating rate of 9.5℃ / min and hold for 14min for melting. During the melting process, cover the surface of the copper liquid with flake graphite and introduce high-purity helium for protection. The helium flow rate is controlled at 4.5L / min. At the same time, microwave assistance is used for 14min.

[0073] Step S5, refining, solidification and casting: After the temperature of the copper liquid is stabilized, a refining agent is added and the mixture is stirred electromagnetically for 12.5 minutes. An ultrasonic probe and an electromagnetic coil are simultaneously inserted into the copper liquid for ultrasonic-electromagnetic synergistic treatment. The slag is removed and the mixture is filtered using a ceramic filter. The filtrate is poured into a graphite mold preheated to 315°C. Directional solidification technology is used, with a cooling device installed at the bottom of the mold. The cooling rate is controlled at 53°C / s, allowing the copper liquid to solidify from the bottom up to obtain an oxygen-free copper ingot.

[0074] Step S6, Post-processing: The oxygen-free copper ingot is subjected to heat treatment and hot rolling in sequence to obtain oxygen-free copper.

[0075] The sputtering deposition power in step S1 is 190W, and the deposition time is 14 minutes. The ultrasonic-plasma combined cleaning in step S1 specifically involves: first, the crude copper is placed in an ultrasonic cleaning tank, where it is subjected to 40kHz high-frequency ultrasound in conjunction with an alkaline cleaning agent to remove surface oil and loose impurities; then, it enters a low-temperature plasma treatment chamber, where argon plasma bombardment removes stubborn oxides and residual impurities, achieving a surface cleanliness of Ra≤0.8μm for the crude copper. The forward current density of the square wave pulse current in step S2 is 340A / m. 2 The pulse frequency is 900Hz, the duty cycle is 68%, and the negative current density is 150A / m. 2 Within each pulse cycle, the forward current promotes copper ion deposition, while the reverse current eliminates concentration polarization on the electrode surface, improving the quality of copper crystallization at the cathode. The electrolysis temperature in step S2 is 58°C. The surfactant in step S2 is a mixture of sodium dodecylbenzenesulfonate and polyethylene glycol 400 in a mass ratio of 1:1.8.

[0076] The purity of the high-purity helium gas mentioned in step S4 is not less than 99.999%; the vacuum level set in step S4 is 1.8 × 10⁻⁶. -5 Pa; the thickness of the flake graphite in step S4 is 105 mm; the frequency of the microwave in step S4 is 2.7 GHz and the power is 1900 W; the mass ratio of copper liquid to refining agent in step S5 is 100:0.009; the refining agent in step S5 includes the following components by weight: boron 1.1 parts, zirconium 0.75 parts, titanium 3.5 parts, aluminum 4.5 parts, yttrium 1.8 parts, sodium fluorosilicate 4.5 parts, calcium fluoride 5.5 parts; the ultrasonic frequency of the ultrasonic-electromagnetic synergistic treatment in step S5 is 75 kHz, the power is 350 W, the magnetic field strength generated by the electromagnetic coil is 0.5 T, and the treatment time is 19 minutes; the temperature of the heat treatment in step S6 is 615℃, and the holding time is 1 h.

[0077] Example 5

[0078] A process for producing oxygen-free copper includes the following steps:

[0079] Step S1, Raw material pretreatment: After chemical polishing and hydrophilic treatment, the high-purity copper sheet is sputtered in a magnetron sputtering equipment with a high-purity copper target under an argon atmosphere to form a uniform copper seed crystal layer; the crude copper is then subjected to ultrasonic-plasma combined cleaning.

[0080] Step S2, Preparation of Electrolytic Copper: Using crude copper treated in step S1 as the anode and high-purity copper sheet treated in step S1 as the cathode, electrolysis is performed using a square wave pulsed current to obtain electrolytic copper. The electrolyte used is deionized water as the solvent and includes the following components at the following concentrations: copper sulfate pentahydrate 200 g / L, sulfuric acid 140 g / L, hydroxyethyl hexahydrotriazine 10 mg / L, glyceryl phosphorylcholine 4 mg / L, surfactant 0.8 g / L, tea polyphenols 3 mg / L, adenosine 3 mg / L, and disodium ethylenediaminetetraacetate 0.8 g / L.

[0081] Step S3, Pretreatment of electrolytic copper: Crush the electrolytic copper into small pieces, place them in an ultrasonic cleaner, add a 5% (w / w) dilute sulfuric acid solution, and soak for 22 minutes at an ultrasonic frequency of 40kHz and a power of 300W; then rinse with deionized water until neutral, and finally dry in a constant temperature drying oven at 90℃ for 4 hours.

[0082] Step S4, Vacuum Melting and Microwave Assistance: Place the pretreated electrolytic copper into a vacuum induction melting furnace, evacuate and continuously introduce high-purity helium to remove oxygen. When the set vacuum degree is reached, heat to 1240℃ at a heating rate of 10℃ / min and hold for 15min for melting. During the melting process, cover the surface of the copper liquid with flake graphite and introduce high-purity helium for protection. The helium flow rate is controlled at 5L / min. At the same time, microwave assistance is used for 15min.

[0083] Step S5, Refining, Solidification and Casting: After the temperature of the copper liquid is stabilized, a refining agent is added and the mixture is stirred electromagnetically for 13 minutes. An ultrasonic probe and an electromagnetic coil are simultaneously inserted into the copper liquid for ultrasonic-electromagnetic synergistic treatment. The slag is removed, and the mixture is filtered using a ceramic filter. The filtrate is poured into a graphite mold preheated to 320°C. Directional solidification technology is used, and a cooling device is set at the bottom of the mold. The cooling rate is controlled at 55°C / s, so that the copper liquid solidifies from the bottom up to obtain an oxygen-free copper ingot.

[0084] Step S6, Post-processing: The oxygen-free copper ingot is subjected to heat treatment and hot rolling in sequence to obtain oxygen-free copper.

[0085] The sputtering deposition power in step S1 is 200W, and the deposition time is 15 minutes. The ultrasonic-plasma combined cleaning in step S1 specifically involves: first, the crude copper is placed in an ultrasonic cleaning tank, where it is subjected to 40kHz high-frequency ultrasound in conjunction with an alkaline cleaning agent to remove surface oil and loose impurities; then, it enters a low-temperature plasma treatment chamber, where argon plasma bombardment removes stubborn oxides and residual impurities, achieving a surface cleanliness of Ra≤0.8μm for the crude copper. The forward current density of the square wave pulse current in step S2 is 350A / m. 2 The pulse frequency is 1000Hz, the duty cycle is 70%, and the negative current density is 160A / m.2 Within each pulse cycle, the forward current promotes copper ion deposition, while the reverse current eliminates concentration polarization on the electrode surface, improving the quality of cathode copper crystallization. The electrolysis temperature in step S2 is 60°C. The surfactant in step S2 is a mixture of sodium dodecylbenzenesulfonate and polyethylene glycol 400 in a mass ratio of 1:2.

[0086] The purity of the high-purity helium gas mentioned in step S4 is not less than 99.999%; the vacuum degree set in step S4 is 2×10⁻⁶. -5 Pa; the thickness of the flake graphite in step S4 is 110 mm; the frequency of the microwave in step S4 is 2.8 GHz and the power is 2000 W; the mass ratio of copper liquid to refining agent in step S5 is 100:0.01; the refining agent in step S5 includes the following components by weight: boron 1.2 parts, zirconium 0.8 parts, titanium 4 parts, aluminum 5 parts, yttrium 2 parts, sodium fluorosilicate 5 parts, calcium fluoride 6 parts; the ultrasonic frequency of the ultrasonic-electromagnetic synergistic treatment in step S5 is 80 kHz, the power is 400 W, the magnetic field strength generated by the electromagnetic coil is 0.5 T, and the treatment time is 20 minutes; the temperature of the heat treatment in step S6 is 620℃, and the holding time is 1 h.

[0087] Comparative Example 1

[0088] This example provides a process for producing oxygen-free copper, which is basically the same as in Example 1, except that glycerol phosphorylcholine and zirconium are not added.

[0089] Comparative Example 2

[0090] This example provides a process for producing oxygen-free copper, which is basically the same as in Example 1, except that adenosine and titanium are not added.

[0091] Comparative Example 3

[0092] This example provides an oxygen-free copper production process, which is basically the same as that in Example 1, except that it does not include sputtering coating and microwave-assisted steps, and uses a current density of 250 A / m. 2 The current replaces the square wave pulse current.

[0093] To further illustrate the beneficial technical effects of the oxygen-free copper production process involved in the various embodiments of the present invention, the composition of the oxygen-free copper produced by the oxygen-free copper production process involved in Examples 1-5 and Comparative Examples 1-3 was analyzed, and its tensile properties were tested according to GB / T228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature". The results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As can be seen from the table above, the oxygen-free copper produced by the oxygen-free copper production process involved in the various embodiments of the present invention has higher purity, tensile strength and lower oxygen content than the comparative product. The combined use of glycerol phosphorylcholine, zirconium, adenosine, titanium, sputtering coating, microwave assistance and square wave pulse current is beneficial to improving purity and mechanical properties and reducing oxygen content.

[0097] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A process for producing oxygen-free copper, characterized in that, Includes the following steps: Step S1, Raw material pretreatment: After chemical polishing and hydrophilic treatment, the high-purity copper sheet is sputtered in a magnetron sputtering equipment with a high-purity copper target under an argon atmosphere to form a uniform copper seed crystal layer; the crude copper is then subjected to ultrasonic-plasma combined cleaning. Step S2, Preparation of Electrolytic Copper: Using crude copper treated in step S1 as the anode and high-purity copper sheet treated in step S1 as the cathode, electrolysis is performed using a square wave pulse current to obtain electrolytic copper; the electrolyte used in the electrolysis is deionized water as the solvent, and includes the following components at the following concentrations: copper sulfate pentahydrate 150-200 g / L, sulfuric acid 110-140 g / L, hydroxyethyl hexahydrotriazine 6-10 mg / L, glyceryl phosphorylcholine 1-4 mg / L, surfactant 0.3-0.8 g / L, tea polyphenols 1-3 mg / L, adenosine 0.1-3 mg / L, and disodium ethylenediaminetetraacetate 0.1-0.8 g / L; the surfactant is sodium dodecylbenzenesulfonate and polyethylene glycol 400 mixed in a mass ratio of 1:(1-2); Step S3, Pretreatment of electrolytic copper: The electrolytic copper is broken into small pieces and then pretreated. Step S4, Vacuum Melting and Microwave Assistance: Place the pretreated electrolytic copper into a vacuum induction melting furnace, evacuate and continuously introduce high-purity helium to remove oxygen. When the set vacuum degree is reached, heat to 1200-1240℃ at a heating rate of 6-10℃ / min and hold for 10-15min for melting. During the melting process, cover the surface of the copper liquid with flake graphite and introduce high-purity helium for protection. The helium flow rate is controlled at 3-5L / min. At the same time, microwave assistance is used for 10-15min. Step S5, Refining and Solidification Casting: After the copper liquid temperature stabilizes, add the refining agent and stir electromagnetically for 10-13 minutes. Simultaneously insert an ultrasonic probe and an electromagnetic coil into the copper liquid for ultrasonic-electromagnetic synergistic treatment. Remove slag, filter using a ceramic filter, and pour the filtrate into a graphite mold preheated to 300-320℃. Use directional solidification technology, with a cooling device at the bottom of the mold, controlling the cooling rate at 45-55℃ / s, so that the copper liquid solidifies from the bottom up to obtain an oxygen-free copper ingot. The mass ratio of the copper liquid to the refining agent is 100:(0.005-0.01). The refining agent includes the following components by weight: boron 0.8-1.2 parts, zirconium 0.5-0.8 parts, titanium 2-4 parts, aluminum 3-5 parts, yttrium 1-2 parts, sodium fluorosilicate 3-5 parts, and calcium fluoride 4-6 parts. Step S6, Post-processing: The oxygen-free copper ingot is subjected to heat treatment and hot rolling in sequence to obtain oxygen-free copper.

2. The oxygen-free copper production process according to claim 1, characterized in that, The sputtering coating power in step S1 is 150-200W, and the deposition time is 10-15 minutes. The ultrasonic-plasma combined cleaning in step S1 is as follows: the crude copper is first put into an ultrasonic cleaning tank, and under the action of 40kHz high-frequency ultrasonic waves, an alkaline cleaning agent is used to remove surface oil and loose impurities. Then it enters a low-temperature plasma treatment chamber, where argon plasma bombardment is used to remove stubborn oxides and residual impurities, so that the surface cleanliness of the crude copper reaches Ra≤0.8μm.

3. The oxygen-free copper production process according to claim 1, characterized in that, In step S2, the positive current density of the square wave pulse current is 300-350 A / m², the pulse frequency is 500-1000 Hz, and the duty cycle is 60%-70%; the negative current density is 100-160 A / m². Within each pulse cycle, the positive current promotes copper ion deposition, while the reverse current eliminates concentration polarization on the electrode surface and improves the quality of cathode copper crystallization. The electrolysis temperature in step S2 is 50-60℃.

4. The oxygen-free copper production process according to claim 1, characterized in that, The pretreatment described in step S3 is as follows: place the small piece of electrolytic copper in an ultrasonic cleaner, add a dilute sulfuric acid solution with a mass fraction of 1-5%, and soak it for 15-22 minutes at an ultrasonic frequency of 40kHz and a power of 300W; then rinse it with deionized water until neutral, and finally dry it in a constant temperature drying oven at 80-90℃ for 3-4 hours.

5. The oxygen-free copper production process according to claim 1, characterized in that, The purity of the high-purity helium gas mentioned in step S4 is not less than 99.999%; the set vacuum degree mentioned in step S4 is (1-2)×10 -5 Pa.

6. The oxygen-free copper production process according to claim 1, characterized in that, The thickness of the flake graphite in step S4 is 90-110 mm; the frequency of the microwave in step S4 is 2.0-2.8 GHz, and the power is 1000-2000 W.

7. The oxygen-free copper production process according to claim 1, characterized in that, In step S5, the ultrasonic frequency of the ultrasonic-electromagnetic synergistic treatment is 40-80kHz, the power is 200-400W, the magnetic field strength generated by the electromagnetic coil is 0.5T, and the processing time is 15-20 minutes.

8. The oxygen-free copper production process according to claim 1, characterized in that, The heat treatment temperature in step S6 is 600-620℃, and the holding time is 1-1.5h.

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