Surface treatment method of easily oxidized copper materials and corrosion-resistant copper materials

Abstract

The present invention provides a surface treatment method for easily oxidized copper materials and a corrosion-resistant copper material. The surface treatment method comprises: placing a clean copper material in a surface treatment liquid, reacting the material, and then washing and drying the material after the reaction to obtain the corrosion-resistant copper material; wherein the surface treatment liquid comprises a formate aqueous solution and a polar stabilizer. The clean copper material is surface treated by combining the formate solution and the polar stabilizer. During the treatment process, the formate ions in the formate can be effectively adsorbed onto the surface of the fresh, clean copper material to form a surface treatment layer with a progressive structure, so that the entire surface treatment layer presents a Cu(110) structure. These characteristics make it difficult for oxygen or other adsorbates to interact with the copper under the passivation layer, thereby presenting corrosion-resistant properties. The polar stabilizer in the surface treatment liquid can prevent the copper material from oxidizing and discoloring due to temperature increase during the surface treatment process, thereby stabilizing the copper material surface from oxidation.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment of copper and its alloys, and in particular to a surface treatment method of easily oxidized copper materials and corrosion-resistant copper materials. Background Art

[0002] Copper alloys can oxidize, discolor, and corrode due to various factors during production, transportation, storage, and use. This is particularly true when relative humidity exceeds the critical humidity, sulfur dioxide is oxidized by water molecules to form SO₃, forming the weakly acidic H₂SO₄. Chloride particles in the air of coastal areas, smog, and polluted areas with high levels of acidic dust and smoke, as well as alkaline conditions, increase the likelihood of copper oxidative discoloration. Consequently, there is a pressing need for surface protection technologies that can maintain the superior electrical and thermal conductivity of copper and its alloys while also offering excellent corrosion resistance. Research in this area is underway both domestically and internationally.

[0003] Patent CN107475700A discloses a method for treating the surface of a corrosion-resistant copper alloy. The corrosion resistance of the treated copper alloy surface in alkaline and salt spray environments is improved. However, this method requires the copper material to be treated in a high-temperature and high-pressure container. Due to the limited space and size of the equipment, the treated sample is small and the operation is inconvenient. The required equipment involves high pressure and is in a high-pressure container, which poses certain risks and is difficult to apply industrially. It is also impossible to replenish the solution online in real time according to changes in solution concentration during the copper material treatment process.

[0004] Patent CN111799012A discloses an antioxidant copper material and its preparation method. The antioxidant copper material is a copper material with formate and thiol modified on its surface. The thiol compound adsorbs on the formate-modified copper surface, forming a self-assembled film, further enhancing the copper's corrosion resistance. However, this method can only process small samples and is not suitable for large-scale copper processing and industrialization. It also cannot provide online, real-time replenishment of solution lost during copper processing.

[0005] Therefore, it is necessary to develop a simple, efficient and continuously processable copper surface corrosion and oxidation resistance technology to solve the problem of oxidation and discoloration of copper strips, foils and wires during production, transportation, storage and use. Summary of the Invention

[0006] The main purpose of the present invention is to provide a surface treatment method for easily oxidized copper materials and a corrosion-resistant copper material, so as to solve the problem of easy oxidation and discoloration of the copper material surface in the prior art.

[0007] To achieve the above-mentioned object, according to one aspect of the present invention, a surface treatment method for easily oxidized copper material is provided, the surface treatment method comprising: placing a copper material with a clean surface in a surface treatment liquid, carrying out a reaction, and washing and drying after the reaction to obtain a corrosion-resistant copper material; wherein the surface treatment liquid comprises an aqueous formate solution and a polar stabilizer.

[0008] Furthermore, the formate includes any one or more of sodium formate, lithium formate, zinc formate, iron formate and copper formate;

[0009] Preferably, the concentration of the formate aqueous solution is 10-15 g / L.

[0010] Furthermore, the polar stabilizer includes any one or more of ethylene glycol, dodecanethiol, dimethylformamide and oleylamine;

[0011] Preferably, the volume ratio of the formate aqueous solution to the polar stabilizer is 100:1 to 90:1.

[0012] Furthermore, the reaction temperature is 100-200° C., and the reaction time is preferably 3-20 h.

[0013] Furthermore, the reaction is carried out in a circulation treatment device at a pressure of 0.1 to 1.56 MPa. Preferably, the circulation treatment device can automatically replenish liquid and is configured to adjust the concentration of the surface treatment liquid in the device.

[0014] Furthermore, a copper material with a clean surface is prepared by the following steps: step S01, subjecting the copper material to ultrasonic degreasing and oil removal treatment, cleaning, and drying to obtain a degreasing and oil-removed copper material, preferably the ultrasonic degreasing and oil removal treatment is performed at a frequency of 25 to 35 kHz, a temperature of 40 to 60° C., and a time of 20 to 80 seconds; step S02, subjecting the degreasing and oil-removing copper material to pickling to remove oxide scale, cleaning, and drying to obtain a copper material with a clean surface;

[0015] Preferably, the cleaning and drying are carried out in an ultrasonic cleaning and drying device, and further preferably, the drying temperature is 60 to 80°C;

[0016] Preferably, the surface-cleaned copper material obtained in step S02 reacts within 15 minutes.

[0017] Furthermore, the pickling solution includes an acid and an oxidant; preferably, the acid includes any one or more of sulfuric acid, nitric acid and hydrochloric acid, and preferably, the oxidant includes any one or more of hydrogen peroxide, nitric acid and nitrates;

[0018] Preferably, the pickling temperature is 40-60°C.

[0019] Furthermore, the copper material includes any one or more of high-copper alloy and pure copper.

[0020] Furthermore, the obtained corrosion-resistant copper material is subjected to BTA passivation treatment to obtain a double-modified corrosion-resistant copper material; preferably, the temperature of the BTA passivation treatment is 60°C to 80°C, and the holding time is 1 to 3 minutes. Preferably, during the BTA passivation treatment, the concentration of BTA in the aqueous solution is 80 to 100 g / L; preferably, the thickness of the treatment layer of the double-modified corrosion-resistant copper material is 150 nm to 300 nm.

[0021] According to another aspect of the present invention, a corrosion-resistant copper material is provided. The corrosion-resistant copper material is obtained by any one of the above-mentioned surface treatment methods.

[0022] The technical solution of the present invention is applied to the surface treatment of clean copper material by combining formate solution and polar stabilizer. During the treatment process, the formate ions in the formate solution can be effectively adsorbed to the surface of the fresh and clean copper material, forming a surface treatment layer with a progressive structure, wherein the atomic valence of the copper on the outermost surface is +2, and the atomic valence of the copper on the subsurface is +1. The valence of copper decreases from 2 valence in the binuclear copper motif to 1 valence, and decreases to 0 valence inside the copper atom. All exposed copper sites on the outermost surface are already in an oxidized state, and the copper atoms on the subsurface are completely covered by O 2- and OH - The surface treatment layer exhibits a Cu(110) structure due to the combination of the two groups. These properties make it difficult for oxygen or other adsorbates to interact with the copper beneath the passivation layer, resulting in corrosion resistance. The polar stabilizer in the surface treatment solution prevents the copper from oxidizing and discoloring due to temperature increases during the surface treatment process, thereby stabilizing the copper surface from oxidation. The preparation process of the present invention can be used for the treatment of large-scale copper coils and can adopt a continuous treatment method, making it suitable for large-scale production of copper. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 The figure shows the comparison results of polarization curves before and after treatment of the sample according to Example 1 of the present invention;

[0025] Figure 2 The polarization curve comparison results of the sample before and after treatment according to Example 8 of the present invention are shown;

[0026] Figure 3 The surface morphology test results of the C11000 sample after being treated in Example 8 of the present invention and immersed in a 0.1M NaOH solution for 24 hours are shown;

[0027] Figure 4The energy spectrum test results of the C11000 sample after being treated in Example 8 of the present invention and immersed in a 0.1M NaOH solution for 24 hours are shown;

[0028] Figure 5 The surface morphology test results of the untreated C11000 sample after immersion in 0.1M NaOH solution for 24 hours according to Example 8 of the present invention are shown;

[0029] Figure 6 The results of the surface energy spectrum test of the untreated C11000 sample after immersion in 0.1M NaOH solution for 24 hours in Example 8 of the present invention are shown;

[0030] Figure 7 The morphology of the C11000 sample treated in Example 8 of the present invention and the untreated C11000 sample after being immersed in a 0.1M NaOH solution for 24 hours is shown;

[0031] Figure 8 The surface morphology of the copper material after being treated according to Example 1 of the present invention and Comparative Example 1 is shown. DETAILED DESCRIPTION

[0032] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0033] As analyzed in the background technology of this application, there is a problem in the prior art that the surface of copper materials is prone to oxidation and discoloration, and the current surface treatment methods of copper materials are complicated or have small processing capacity, low efficiency, or are difficult to process large-volume samples. Based on this, the present application provides a surface treatment method for easily oxidized copper materials and corrosion-resistant copper materials.

[0034] According to a typical embodiment of the present application, a surface treatment method for easily oxidized copper material is provided, the method comprising: placing a copper material with a clean surface in a surface treatment liquid, reacting, and cleaning and drying after the reaction to obtain a corrosion-resistant copper material; wherein the surface treatment liquid comprises an aqueous formate solution and a polar stabilizer.

[0035] The treatment method of the present application uses a formate solution and a polar stabilizer to perform surface treatment on clean copper materials. During the treatment process, the formate ions in the formate solution can be effectively adsorbed onto the surface of the fresh and clean copper material, forming a surface treatment layer with a progressive structure, wherein the atomic valence of the copper on the outermost surface is +2, and the atomic valence of the copper on the subsurface is +1. The valence of copper decreases from 2 valence in the binuclear copper motif to 1 valence, and decreases to 0 valence inside the copper atoms. All exposed copper sites on the outermost surface are already in an oxidized state, and the copper atoms on the subsurface are completely covered by O 2- and OH -The surface treatment layer exhibits a Cu(110) structure due to the combination of the two groups. These properties make it difficult for oxygen or other adsorbates to interact with the copper beneath the passivation layer, resulting in corrosion resistance. The polar stabilizer in the surface treatment solution prevents the copper from oxidizing and discoloring due to temperature increases during the surface treatment process, thereby stabilizing the copper surface from oxidation. The preparation process of the present invention can be used for the treatment of large-scale copper coils and can adopt a continuous treatment method, making it suitable for large-scale production of copper.

[0036] The formate salt can be selected from existing technologies, for example, including but not limited to any one or more of sodium formate, lithium formate, zinc formate, iron formate, and copper formate. In some preferred embodiments of the present application, the concentration of the formate salt solution is 10-15 g / L, which has a good surface treatment effect on the copper material.

[0037] In some typical embodiments of the present application, the polar stabilizer includes any one or more of ethylene glycol, dodecanethiol, dimethylformamide, and oleylamine, which effectively stabilizes the copper material during the surface treatment reaction and effectively prevents oxidation and discoloration on the copper surface. In some embodiments of the present application, the volume ratio of the formate aqueous solution to the polar stabilizer is 100:1 to 90:1, which can better exert the synergistic effect of the two, further enhance the corrosion resistance of the copper material, and provide a good surface morphology.

[0038] In some embodiments of the present application, the temperature of the copper material in the surface treatment solution is 100-200°C to allow the formate to fully react with the copper material. The reaction time is preferably 3-20 hours to obtain a treatment layer of suitable thickness, further improving the corrosion resistance of the copper material. Preferably, the thickness of the treatment layer on the surface of the copper material after the above treatment is 150nm-300nm, which provides a certain corrosion resistance thickness without affecting the electrical and thermal conductivity of the copper material substrate.

[0039] In some typical embodiments of the present application, the above-mentioned reaction is carried out in a circulating treatment device. By adopting a low-pressure circulating treatment device with a pressure of 0.1 to 1.56 MPa, the steam generated due to the high temperature during the reaction can be continuously condensed in the circulating device and re-entered into the reaction vessel, so that the treatment liquid reaches a suitable reaction temperature. Compared with treatment in a high-pressure vessel, the use of a circulating treatment device only requires a lower pressure environment to obtain a good surface treatment effect, avoiding the safety hazards of using a high-pressure vessel, while significantly reducing equipment investment costs.

[0040] Technicians in this field can select a specific low-pressure circulation treatment device based on the existing technology. Since the reaction is carried out under relatively low pressure, compared with the use of high-pressure pressure-resistant containers, the low-pressure circulation treatment device used in this application is safe and stable, with relatively small volume restrictions, and can realize the processing of large-volume samples; on the other hand, the equipment investment is relatively small, easy to implement, and highly safe; in addition, energy consumption can also be effectively reduced through energy recovery and utilization.

[0041] Because formate is consumed during the surface treatment reaction, in order to maintain the formate concentration in the surface treatment fluid within an optimal range and improve treatment speed and effectiveness, in some preferred embodiments of the present application, the circulating treatment device is capable of automatic refilling, i.e., is equipped with an automatic refilling device configured to adjust the concentration of the surface treatment fluid within the device, particularly the formate concentration. To further achieve the regulation of the formate concentration, a formate concentration detection device can be provided to monitor the formate concentration online, and refill the fluid based on the test results, further improving the control accuracy.

[0042] By circulating the surface treatment liquid and real-time monitoring of the replenishment method, the copper surface can be modified and protected by formate ions, thereby further improving the corrosion resistance of easily oxidized copper materials such as strips, foils and wires.

[0043] Cleaning the surface of the copper material to obtain the above-mentioned surface-cleaned copper material is the key to effectively improving the corrosion resistance of the copper material during subsequent processing. The method for cleaning the surface of the copper material can adopt the methods of the existing technology. In some embodiments of the present application, the surface-cleaned copper material is prepared by the following steps: Step S01, ultrasonically degreasing and deoiling the copper material, washing, and drying to obtain a degreased and deoiled copper material; Step S02, pickling the degreased and deoiled copper material to remove oxide scale, washing, and drying to obtain a surface-cleaned copper material.

[0044] In step S1 of the present invention, the easily oxidized copper material is first subjected to ultrasonic degreasing treatment. The purpose is to remove the residual grease in the easily oxidized copper material more thoroughly through the ultrasonic treatment process of the present invention. Then, the oxide scale in the easily oxidized copper material is removed through the pickling process, and the residual liquid in the pickling stage is cleaned, thereby obtaining a fresh and crystalline surface of the easily oxidized copper material, which can further improve the corrosion resistance of the subsequent surface treatment reaction.

[0045] The ultrasonic degreasing treatment preferably has a frequency of 25-35 kHz, a temperature of 40-60°C, and a duration of 20-80 seconds, which effectively removes grease from the copper material. The cleaning and drying of steps S01 and S02 can be performed in an ultrasonic cleaning and drying device. This device can more thoroughly and cleanly remove residual liquid from the degreasing stage, and can also clean residual liquid from the pickling stage. A drying temperature of 60-80°C is further preferred, which not only improves the cleaning and drying effects but also helps further improve treatment efficiency.

[0046] To prevent the copper material from being re-oxidized or contaminated after surface treatment, the cleaned copper material is placed in the surface treatment solution as soon as possible for reaction. In some embodiments of the present application, the surface-cleaned copper material obtained in step S02 is reacted within 15 minutes, for example, immediately after surface cleaning, or within 5 minutes, or within 10 minutes.

[0047] In some preferred embodiments, the pickling solution includes an acid and an oxidizing agent, which more cleanly and quickly removes copper oxide scale. Preferably, the acid includes one or more of sulfuric acid, hydrochloric acid, and nitric acid, which achieves better pickling results. Preferably, the oxidizing agent includes one or more of hydrogen peroxide, nitric acid, and nitrates, which further enhances the pickling effect. Preferably, the pickling temperature is 40-60°C, further enhancing pickling efficiency.

[0048] In some embodiments of the present application, the pickling solution includes sulfuric acid and hydrogen peroxide, and the pickling effect is significantly improved. Preferably, the concentration of sulfuric acid is 80-100 g / L, and the concentration of hydrogen peroxide is 40-60 g / L, which is particularly effective in removing copper oxide scale.

[0049] In some other embodiments of the present application, the pickling solution includes sulfuric acid, hydrochloric acid, and nitric acid. Preferably, the sulfuric acid concentration in the pickling solution is 120-150 g / L, the hydrochloric acid concentration is 30-50 g / L, and the sodium nitrate concentration is 60-90 g / L, and the pickling effect is significantly improved. When using this pickling solution, the pickling temperature is preferably 40-50°C and the pickling time is 20-50 seconds, which can better balance the pickling effect and efficiency.

[0050] The copper material undergoing surface cleaning or the raw material for the surface cleaning is not particularly limited in shape or volume, and includes, but is not limited to, easily oxidized copper strip, copper foil, or wire. The copper material can be made of any one or more of high-copper alloys and pure copper. Examples of high-copper alloys include copper-iron-phosphorus alloys and copper-chromium-zirconium alloys, while examples of pure copper include C10100, C10200, and C11000 alloys.

[0051] In some embodiments of the present application, to further enhance the corrosion resistance of easily oxidized copper, the corrosion-resistant copper obtained by the above method is subjected to a BTA passivation treatment to obtain a double-modified corrosion-resistant copper. BTA, or benzotriazole, can form a stable BTA-Cu complex with +2 or +1 copper, forming a passivation film on the surface, thereby further enhancing the corrosion resistance of the easily oxidized copper. Copper treated with formate and BTA exhibits superior resistance to oxidative corrosion compared to treatment with formate alone, BTA alone, or other treatments, thereby suppressing oxidative discoloration during production, transportation, storage, and use.

[0052] The BTA passivation treatment temperature is preferably 60°C to 80°C, and the holding time is 1 to 3 minutes, which has a better passivation effect. Preferably, during the BTA passivation treatment, the concentration of BTA in the aqueous solution is 80 to 100 g / L. This concentration of BTA solution can synergize with the surface layer of the copper material treated above, further improving the passivation effect. In some embodiments of the present application, the thickness of the treated layer of the double-modified corrosion-resistant copper material treated above is 150 nm to 300 nm.

[0053] According to another typical embodiment of the present application, a corrosion-resistant copper material is provided, which is obtained by any of the above-mentioned surface treatment methods.

[0054] The treatment method of the present application uses a formate solution and a polar stabilizer to perform surface treatment on clean copper materials. During the treatment process, the formate ions in the formate solution can be effectively adsorbed onto the surface of the fresh and clean copper material, forming a surface treatment layer with a progressive structure, wherein the atomic valence of the copper on the outermost surface is +2, and the atomic valence of the copper on the subsurface is +1. The valence of copper decreases from 2 valence in the binuclear copper motif to 1 valence, and decreases to 0 valence inside the copper atoms. All exposed copper sites on the outermost surface are already in an oxidized state, and the copper atoms on the subsurface are completely covered by O 2- and OH - The surface treatment layer exhibits a Cu(110) structure due to the combination of the two groups. These properties make it difficult for oxygen or other adsorbates to interact with the copper beneath the passivation layer, resulting in corrosion resistance. The polar stabilizer in the surface treatment solution prevents the copper from oxidizing and discoloring due to temperature increases during the surface treatment process, thereby stabilizing the copper surface from oxidation. The preparation process of the present invention can be used for the treatment of large-scale copper coils and can adopt a continuous treatment method, making it suitable for large-scale production of copper.

[0055] The beneficial effects that can be achieved by the present application will be further illustrated below with reference to examples and comparative examples.

[0056] Example 1

[0057] (1) Select copper-iron-phosphorus alloy strips, perform ultrasonic degreasing and oil removal on the surface, the oil removal process is 25kHz, the temperature is 40℃, and the oil removal time is 80s, then clean and dry in an ultrasonic cleaning and drying device, the drying temperature is 60℃, and then pickle in a copper pickling device to remove the oxide scale in the easily oxidized copper material, the pickling process is 80g / L sulfuric acid and 60g / L hydrogen peroxide, the pickling temperature is 60℃, and then clean and dry in an ultrasonic cleaning and drying device, the drying temperature is 60℃, to obtain a fresh and clean surface copper material, and the copper material waiting time is 1min;

[0058] (2) A mixed solution of sodium formate and dimethylformamide is prepared, wherein the concentration of the sodium formate aqueous solution is 10 g / L, and the volume ratio of the sodium formate aqueous solution to the dimethylformamide polar stabilizer is 100:1.

[0059] (3) The surface-treated copper-iron-phosphorus alloy strip and a mixed solution of sodium formate and dimethylformamide were reacted in a circulating treatment device at a reaction temperature of 100°C for a reaction time of 20 hours. The solution was automatically replenished according to the concentration change of the surface treatment solution to maintain the concentration of sodium formate in the mixed solution within the range of (10±2) g / L. The surface-treated copper material was cleaned and dried in an ultrasonic cleaning and drying device at a drying temperature of 60°C to obtain a surface-treated copper material with good corrosion resistance. The surface was bright and clean, showing the color of the original material without color difference.

[0060] (4) The surface-treated copper material obtained in step (3) is further treated in a BTA passivation treatment device, with the following treatment process: treatment time 60° C., holding time 3 min, solution ratio 80 g / L, and then cleaned and dried in an ultrasonic cleaning and drying device at a drying temperature of 60° C. to obtain a final double-modified surface-treated copper-iron-phosphorus strip with excellent corrosion resistance. By sectioning and transmission electron microscopy scanning, the thickness of the surface treatment layer is measured to be 200 nm.

[0061] The surface morphology of the copper-iron-phosphorus alloy strip after treatment is as follows: Figure 8 As shown in the picture on the left.

[0062] The processing procedures of Examples 2 to 8 are the same as those of Example 1, and their specific process parameters are shown in the corresponding data in Tables 1 to 3.

[0063] Table 1

[0064]

[0065] Table 2

[0066]

[0067] Table 3

[0068]

[0069] Example 9

[0070] The difference from Example 1 is that the volume ratio of sodium formate to dimethylformamide polar stabilizer is 110:1.

[0071] Example 10

[0072] The difference from Example 1 is that the volume ratio of sodium formate to dimethylformamide polar stabilizer is 85:1.

[0073] Example 11

[0074] The difference from Example 1 is that the copper material waits for 20 minutes after being treated in step (1).

[0075] Example 12

[0076] The difference from Example 1 is that the copper-iron-phosphorus alloy strip is not subjected to the surface cleaning treatment in step (1) and is directly placed in the circulation treatment device for reaction.

[0077] Example 13

[0078] The difference from Example 1 is that the surface-treated copper material with good corrosion resistance obtained by treatment is directly tested without the subsequent step (4) BTA passivation treatment.

[0079] Example 14

[0080] The difference from Example 1 is that ethylene glycol at the same volume ratio is used instead of dimethylformamide.

[0081] Example 15

[0082] The only difference from Example 1 is that the pickling process is a sulfuric acid concentration of 130 g / L, a hydrochloric acid concentration of 30 g / L, a sodium nitrate concentration of 60 g / L, a pickling temperature of 45°C, and a time of 30 s. The other steps are the same as Example 1.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that the solution prepared in step (2) does not contain dimethylformamide polar stabilizer, but only contains sodium formate aqueous solution of the same concentration.

[0085] The surface morphology of the copper-iron-phosphorus alloy strip after treatment is as follows: Figure 8 As shown in the picture on the right.

[0086] Comparative Example 2

[0087] The difference from Example 1 is that the solution prepared in step (2) does not contain dimethylformamide polar stabilizer, but only sodium formate aqueous solution of the same concentration, and the reaction in step (3) is carried out in a sealed pressure-resistant container, and no sodium formate solution is added during the reaction.

[0088] The copper materials treated in the above examples and comparative examples were immersed in 0.1M NaOH solution for 24 hours, dried, and the surface morphology changes were measured using an X-Rite Ci7800 desktop spectrophotometer. The results are recorded in Table 4 below. Among them, the polarization curves of the samples of Example 1 and Example 8 before and after treatment are compared. Figure 1 、 2 As shown;

[0089] The scanning electron microscope, energy spectrum test results and morphology photos of the C11000 sample of Example 8 before and after the above steps (1) to (4) are as follows: Figures 3 to 7 As shown, Figure 7 In the figure, the left side shows the morphology of the treated C11000 sample after immersion in 0.1M NaOH solution for 24 hours, and the right side shows the morphology of the untreated C11000 sample after immersion in 0.1M NaOH solution for 24 hours.

[0090] The CIE 1976 L*a*b* color space, also known as the CIE LAB color space, is a uniform color space recommended by the CIE (Commission Internationale de L'Eclairage). Because it most closely resembles real visual effects when analyzing color differences between different surface colors, it is widely used in surface colors such as paint, building materials, and metallic hues. It consists of a vertical lightness axis, L*, and two chromaticity axes, a* and b*. The L* axis represents the lightness coordinate of the color, with L* values ranging from 0 to 100, starting from black (L*=0) at the bottom, passing through mid-gray, and ending at white (L*=100) at the top, representing the fully reflected color. The a* axis represents the red-green axis, with a* > 0 indicating a red component in the surface color, and a* < 0 indicating a green component. The b* axis represents the yellow-blue axis, with b* > 0 indicating a yellow component in the surface color, and b* < 0 indicating a blue component. The color difference after a color change is expressed as ΔE. When ΔE is less than 1, the color difference of the alloy surface is basically invisible and acceptable. When ΔE is greater than 1 or even greater, the human eye can distinguish the color difference, which is unacceptable. The copper materials treated in step (3) of the embodiment and comparative example and the copper materials after the final treatment were immersed in 0.1M NaOH solution for 24 hours and tested using an X-Rite Ci7800 desktop spectrophotometer. The values of L, a, b, and ΔE are shown in Table 4.

[0091] Table 4

[0092]

[0093]

[0094] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the treatment method of the present application uses a formate solution and a polar stabilizer to perform surface treatment on clean copper materials. During the treatment process, the formate ions in the formate solution can be effectively adsorbed onto the surface of the fresh and clean copper material to form a surface treatment layer with a progressive structure, wherein the atomic valence of the copper on the outermost surface is +2, and the atomic valence of the copper on the subsurface is +1. The valence of copper decreases from 2 valence in the binuclear copper motif to 1 valence, and decreases to 0 valence inside the copper atom. All exposed copper sites on the outermost surface are already in an oxidized state, and the copper atoms on the subsurface are completely covered by O 2- and OH - The surface treatment layer exhibits a Cu(110) structure due to the combination of the two groups. These properties make it difficult for oxygen or other adsorbates to interact with the copper beneath the passivation layer, resulting in corrosion resistance. The polar stabilizer in the surface treatment solution prevents the copper from oxidizing and discoloring due to temperature increases during the surface treatment process, thereby stabilizing the copper surface from oxidation. The preparation process of the present invention can be used for the treatment of large-scale copper coils and can adopt a continuous treatment method, making it suitable for large-scale production of copper.

[0095] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A surface treatment method for easily oxidized copper material, characterized in that: The method comprises: placing a copper material with a clean surface in a surface treatment solution to react, and then washing and drying the copper material after the reaction is completed to obtain a corrosion-resistant copper material; The surface treatment liquid includes a formate aqueous solution and a polar stabilizer; The concentration of the formate aqueous solution is 10-15 g / L; the formate includes any one or more of sodium formate, lithium formate, zinc formate, iron formate and copper formate; The polar stabilizer includes any one or more of ethylene glycol, dodecanethiol, dimethylformamide and oleylamine; The volume ratio of the formate aqueous solution to the polar stabilizer is 100:1 to 90:1; The reaction temperature is 100-200°C; the reaction time is 3-20 hours; the reaction is carried out in a circulation treatment device at a pressure of 0.1-1.56 MPa; the circulation treatment device is capable of automatic liquid replenishment and is configured to adjust the concentration of the surface treatment liquid in the device; The copper material with cleaned surface is prepared by the following steps: Step S01, performing ultrasonic degreasing and oil removal treatment on the copper material, cleaning and drying to obtain the degreased and oil-removed copper material; Step S02, pickling the degreased and deoiled copper material to remove oxide scale, washing, and drying to obtain the surface-cleaned copper material; the surface-cleaned copper material obtained in step S02 is subjected to the reaction within 15 minutes; The obtained corrosion-resistant copper material is subjected to BTA passivation treatment to obtain a double-modified corrosion-resistant copper material.

2. The surface treatment method according to claim 1, characterized in that The frequency of the ultrasonic degreasing and oil removal treatment is 25-35 kHz, the temperature is 40-60° C., and the time is 20-80 s.

3. The surface treatment method according to claim 1, wherein: The cleaning is carried out in an ultrasonic cleaning device.

4. The surface treatment method according to claim 1, characterized in that The drying is carried out in a drying device.

5. The surface treatment method according to claim 1, characterized in that: The drying temperature is 60-80°C.

6. The surface treatment method according to claim 1, characterized in that: The pickling solution includes acid and oxidant.

7. The surface treatment method according to claim 6, characterized in that: The acid includes any one or more of sulfuric acid, nitric acid and hydrochloric acid.

8. The surface treatment method according to claim 6, characterized in that: The oxidant includes any one or more of hydrogen peroxide and nitrate.

9. The surface treatment method according to claim 6, characterized in that: The pickling temperature is 40-60°C.

10. The surface treatment method according to claim 1, wherein: The copper material includes any one or more of high-copper alloy and pure copper.

11. The surface treatment method according to claim 1, wherein: The temperature of the BTA passivation treatment is 60° C. to 80° C., and the holding time is 1 to 3 minutes.

12. The surface treatment method according to claim 1, wherein: During the BTA passivation treatment, the concentration of BTA in the aqueous solution is 80-100 g / L.

13. The surface treatment method according to claim 1, characterized in that: The thickness of the treatment layer of the double-modified corrosion-resistant copper material is 150nm~300nm.

14. A corrosion-resistant copper material, characterized in that: Obtained by the surface treatment method according to any one of claims 1 to 13.

Images