A corrosion resistant film formed in situ on a copper metal surface and a method of making the same

Abstract

The application discloses an in-situ formed anti-corrosion film on a copper surface and a preparation method thereof, and belongs to the technical field of metal material surface treatment and protection engineering. The anti-corrosion film is a coordination polymer of copper ions and thiol compounds, and is formed in-situ on the copper surface through anodic electrochemical deposition. The anti-corrosion film is prepared by adopting a three-electrode system for electrochemical deposition with metal copper as a working electrode and a solution containing thiol compounds and a supporting electrolyte as an electrolyte. The anti-corrosion film obtained by the application is dense, uniform and stable, and can keep the intrinsic conductivity of copper unchanged, and can also make the copper maintain excellent stability and protection performance in various corrosive environments containing chlorine, acid, alkali and high temperature, and has both anti-corrosion performance and conductivity. Meanwhile, raw materials are cheap and easy to obtain, the process is simple, the conditions are mild, the method is suitable for large-scale preparation, and the application has important application prospect.

Description

Technical Field

[0001] This invention belongs to the field of metal material surface treatment and protection engineering technology, and particularly relates to an anti-corrosion film formed in situ on the surface of metal copper and its preparation method. Background Technology

[0002] Copper is highly favored in the power and electronics industries for its excellent machinability and electrical conductivity, and is widely used in the manufacture of various electrical and electronic devices, from massive power grid systems to nanoscale chip interconnects. Furthermore, copper is used as a material for heat exchange and fluid transport pipelines in fields such as energy and petrochemicals, shipbuilding, seawater desalination, and white goods. However, copper is prone to corrosion in humid environments or when in contact with seawater. This corrosion leads to a decline in copper's electrical and thermal conductivity over long-term use, and can even cause risks such as circuit breaks and pipeline leaks, thus significantly limiting the sustainable application of copper in industry.

[0003] To inhibit copper corrosion, surface coatings are an effective method. These coatings act as physical barriers, isolating the copper substrate from corrosive environments. However, conventional coating materials typically require micrometer-level thickness to effectively suppress the diffusion of corrosive substances such as chlorine, sulfur, and oxygen, which presents challenges in practical applications. For example, polymer coatings such as epoxy resins are prone to aging and cracking, leading to reduced adhesion to the substrate and resulting in localized damage and coating peeling. Furthermore, thicker coatings can also affect the electrical and thermal conductivity of copper, limiting its application scenarios.

[0004] Therefore, the preparation of nanoscale or even molecular-level anti-corrosion films and the improvement of their adhesion to the substrate to maintain excellent electrical and thermal conductivity have become urgent needs for the industrial application of copper. Researchers have attempted to prepare two-dimensional ultrathin nanofilms such as graphene and boron nitride on copper surfaces to prevent corrosion. These films can effectively block the penetration of corrosive molecules such as oxygen molecules and chloride ions, but they still face challenges such as interfacial diffusion, high preparation costs, and difficulties in large-scale preparation. Furthermore, graphene films pose a risk of galvanic corrosion during long-term protection. On the other hand, organic corrosion inhibitors such as benzotriazole adsorb onto the copper surface to form a molecular-level coordination polymer protective layer, which can also slow down copper corrosion. However, the protective layer formed by passive adsorption is usually not dense enough, and its anti-corrosion performance still needs further improvement. Therefore, there is an urgent need for improved technologies to prepare anti-corrosion films with greater applicability. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide an anti-corrosion film formed in situ on the surface of metallic copper and its preparation method. The resulting anti-corrosion film is dense, uniform, and stable, possessing both anti-corrosion and conductive properties, and has significant application prospects.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An anti-corrosion film is provided for in-situ formation on the surface of metallic copper. The anti-corrosion film is a coordination polymer of copper ions and thiol compounds, which is formed in-situ on the copper surface by anodic electrochemical deposition.

[0007] According to the above scheme, the anti-corrosion film is a dense, uniform and stable ultra-thin anti-corrosion film.

[0008] According to the above scheme, the thickness of the anti-corrosion film is 1-10 nm; preferably 3-8 nm.

[0009] According to the above scheme, the anti-corrosion film enables copper to maintain excellent stability and protective performance in various corrosive environments, including chlorine-containing, acidic, alkaline, and high-temperature environments, without affecting the intrinsic conductivity of copper.

[0010] According to the above scheme, the thiol compound is selected from at least one of aromatic compounds or azole compounds containing a free thiol group. Preferably, the thiol compound is 1,4-benzyldithiol or 2-mercaptobenzimidazole.

[0011] According to the above scheme, the specific process of anodic electrochemical deposition is as follows: using metallic copper as the working electrode, using a solution containing thiol compounds and supporting electrolyte as the electrolyte, and performing electrochemical deposition using a three-electrode system.

[0012] Preferably, the supporting electrolyte is at least one of sodium perchlorate, lithium perchlorate, sodium fluoroborate, tetraethyltetrafluoroborate, and tetrabutylfluoroborate.

[0013] Preferably, the concentration of thiols in the electrolyte is 0.01~1000 mmol / L; and the concentration of the supporting electrolyte is 0.01~1 mol / L.

[0014] Preferably, the solvent in the electrolyte is an organic solvent, water, or a mixture thereof; more preferably, the organic solvent is selected from at least one of methanol, ethanol, isopropanol, cyclohexane, and acetonitrile.

[0015] A method for preparing an in-situ corrosion-resistant thin film formed on the surface of the aforementioned metallic copper includes the following steps: Using metallic copper as the working electrode and a solution containing thiol compounds and supporting electrolyte as the electrolyte, an electrochemical deposition is performed using a three-electrode system. This causes copper to undergo an oxidation reaction and coordinate with the thiol compounds in the electrolyte to polymerize in situ on the copper surface, forming a passivation film, thus obtaining an anti-corrosion film.

[0016] According to the above scheme, the copper metal undergoes a cleaning pretreatment, specifically as follows: as needed, sandpaper is used to polish and remove surface contaminants from the copper metal, then the copper is immersed in hydrochloric acid / hot acetic acid solution to remove the oxide layer, and finally ultrasonically cleaned with deionized water and isopropanol. The cleaned copper metal is then stored in isopropanol solvent.

[0017] According to the above scheme, the metallic copper is pure copper or copper alloy, wherein the form is copper block, copper foil or copper wire.

[0018] According to the above scheme, the solvent in the electrolyte is an organic solvent, water, or a mixture thereof. Preferably, the organic solvent is selected from at least one of methanol, ethanol, isopropanol, cyclohexane, and acetonitrile.

[0019] According to the above scheme, the thiol compound is selected from at least one of aromatic compounds or azole compounds containing a free thiol group. Preferably, the thiol compound is 1,4-benzyldithiol or 2-mercaptobenzimidazole.

[0020] According to the above scheme, the concentration of the thiol compound in the electrolyte is 0.01~1000 mmol / L, preferably 1~10 mmol / L.

[0021] According to the above scheme, the supporting electrolyte is at least one of sodium perchlorate, lithium perchlorate, sodium fluoroborate, tetraethyltetrafluoroborate, and tetrabutylfluoroborate. The supporting electrolyte is added to increase the conductivity of the electrolyte.

[0022] According to the above scheme, the concentration of the supporting electrolyte in the electrolyte is 0.01 ~ 1 mol / L.

[0023] According to the above scheme, electrochemical deposition is performed using a constant potential mode.

[0024] According to the above scheme, the electrode potential for electrochemical deposition relative to open circuit is 0 V ~ +1.0 V, and the deposition time is 1 ~ 120 minutes.

[0025] According to the above scheme, in the three-electrode system, metallic copper is used as the working electrode, and Ag / AgCl electrode (aqueous solution system) or Ag / Ag... + The electrode (in a non-aqueous solution system) serves as the reference electrode, while the counter electrode is made of an inert material such as platinum, titanium, or graphite. Preferably, the distance between the working electrode and the counter electrode is 2 to 10 cm.

[0026] The beneficial effects of this invention are as follows: 1. This invention provides an in-situ formed anti-corrosion film on the surface of metallic copper. Using thiol compounds as ligands, the surface copper atoms are directly converted into an anti-corrosion film in situ through electrochemical deposition, utilizing anodic copper oxidation and coordination polymerization processes. This results in a near-separate phase boundary between the film and the copper substrate, with a strong interfacial bond, which is beneficial for achieving higher interfacial continuity and low porosity. Simultaneously, the thiol ligands can form more stable covalent / coordination bonds and bridging sulfur structures with copper atoms, improving the density and chemical and high-temperature stability of the passivation film itself, ultimately obtaining a dense, nanoscale, ultrathin anti-corrosion film. The resulting anti-corrosion film does not affect the intrinsic conductivity of copper, and can maintain excellent stability and protective performance in various corrosive environments such as chlorine-containing environments, acidic, alkaline, and high-temperature environments. It can be applied in industrial fields with high requirements for metal conductivity and environmental stability, such as electronic device manufacturing, energy transmission and distribution systems, microelectronic interconnect structures, heat dissipation devices, and heat exchange pipes, and has important application prospects.

[0027] 2. This invention provides a method for preparing an anti-corrosion film on the surface of metallic copper. A dense, uniform and stable ultrathin anti-corrosion film is obtained in situ through simple electrochemical deposition. The raw materials are inexpensive and readily available, the process is simple and the conditions are mild, making it suitable for large-scale preparation. It can be integrated into roll-to-roll industrial production systems to achieve rapid, low-energy, and continuous processing of copper coils. It has good industrial adaptability and promotion potential. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is the It curve of constant potential electrochemical deposition in Example 1.

[0030] Figure 2 The images show the Raman spectra of the 1,4-benzenedithiol raw material and the copper surface after electrochemical treatment in Example 1.

[0031] Figure 3 This is a TEM image of the cross-section of the copper foil after electrochemical deposition in Example 1.

[0032] Figure 4 This is the XPS spectrum of the copper foil surface after electrochemical deposition in Example 1.

[0033] Figure 5 The image shows the electrokinetic polarization curves of the copper foil in 3.5% NaCl solution before and after electrochemical deposition in Example 1.

[0034] Figure 6 The impedance spectra of the copper foil in 3.5% NaCl solution before and after electrochemical deposition in Example 1 are shown.

[0035] Figure 7 The images show SEM images of bare copper and electrochemically treated copper foil from Example 1 after being placed in a 3.5% NaCl solution for 24 hours.

[0036] Figure 8 This is a comparison of the resistivity of bare copper and electrochemically treated copper foil before and after corrosion in Example 1.

[0037] Figure 9 The image shows the electrokinetic polarization curves of the copper foil in 0.1 mol / L H2SO4 solution before and after electrochemical deposition in Example 2.

[0038] Figure 10 The image shows the electrokinetic polarization curves of the copper foil in 0.1 mol / L NaOH solution before and after electrochemical deposition in Example 3.

[0039] Figure 11 The image shows the electrokinetic polarization curves of the copper wire in 3.5% NaCl solution after oxidation at 100°C for 2 hours before and after electrochemical deposition in Example 4. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0041] Example 1 A method for preparing an in-situ corrosion-resistant thin film formed on a copper surface is provided, comprising the following steps: Uncoated copper foil with a thickness of 25 μm was cut to a size of 1 cm × 2 cm and cleaned in hot acetic acid at 50 °C for 20 min to remove its surface oxide layer. Then, the copper foil was rinsed with deionized water and ultrasonically cleaned in deionized water and isopropanol for 5 min each time. The cleaned sample was stored in isopropanol solvent for later use.

[0042] Measure 50 ml of methanol solvent. Weigh 1.085 g of tetraethylammonium tetrafluoroborate solid powder and dissolve it in the methanol solvent (concentration 0.1 mol / L). This serves as a supporting electrolyte to increase the conductivity of the electrolyte. Then weigh 0.0355 g of 1,4-benzenedithiol (BDT) solid powder and dissolve it in the electrolyte (concentration 1 mmol / L), and sonicate for 15 min to ensure complete dissolution. Store the prepared electrolyte in a sealed container at low temperature to prevent oxidation.

[0043] The electrolyte was injected into a three-electrode electrolytic cell, using Ag / Ag + A 10 mmol / L AgNO3 methanol solution electrode was used as the reference electrode, a copper foil as the working electrode, and a platinum sheet as the counter electrode, with a 3 cm gap between the working and counter electrodes. After electrode connection, electrochemical deposition was performed using a constant potential mode, with a deposition potential of 0.4 V and a deposition time of 30 minutes. After deposition, a coordination polymer anti-corrosion film composed of 1,4-benzenedithiol and copper ions was obtained on the copper foil surface.

[0044] Figure 1 The curve shown is the It curve for electrochemical deposition. The deposition current decreases with deposition time, indicating that a protective layer is formed on the copper foil surface, which inhibits the electrochemical reaction on the copper foil surface.

[0045] Figure 2 The images show the Raman spectra of BDT raw material and the surface of copper foil after electrochemical passivation, indicating that BDT molecules formed coordination polymers during the electrochemical passivation process.

[0046] Figure 3 The image shows a TEM image of the cross-section of the copper foil after electrochemical treatment, indicating that the passivation film thickness is approximately 5.2 nm, thus demonstrating the formation of a nanoscale ultrathin passivation film.

[0047] Figure 4 The XPS spectrum of the copper foil surface after electrochemical treatment confirms the presence of sulfur, indicating that 1,4-benzenedithiol was effectively deposited on the copper foil surface.

[0048] Figure 5 and Figure 6 The figures show the electrodynamic polarization curves and electrochemical impedance spectroscopy of the electrochemically treated copper foil in a 3.5% NaCl aqueous solution, respectively. It can be seen that the electrochemically treated copper foil has a lower corrosion current and a higher charge transfer resistance, indicating that the film can effectively inhibit the corrosion of copper foil in a neutral chloride-containing solution.

[0049] Figure 7 The SEM images of the electrochemically treated copper foil after immersion in a 3.5% NaCl solution for 24 hours show that, compared to bare copper, the surface of the electrochemically passivated copper foil did not show significant corrosion.

[0050] Figure 8 The resistivity of bare copper and passivated copper foil before and after corrosion (immersion in 1 mol / L KOH solution for 12 hours) is compared to that of bare copper (resistivity 3.42 × 10⁻⁶). -8 The conductivity of the copper foil did not change significantly after passivation treatment (resistivity 3.49 × 10⁻⁶ Ωm). -8 The resistivity of bare copper increased significantly (8.69 × 10⁻⁶ Ωm), indicating that passivation treatment has virtually no impact on the conductivity of copper; after etching treatment, the resistivity of bare copper increased significantly (8.69 × 10⁻⁶ Ωm). -8 (Ωm), while the passivated copper foil still maintains good conductivity (resistivity 3.76×10 Ωm), -8 Ωm).

[0051] Example 2 A method for preparing an in-situ corrosion-resistant thin film formed on a copper surface is provided, comprising the following steps: Cut a 1mm thick copper sheet into 3cm x 3cm pieces, polish it with 3000-grit sandpaper, then clean the copper foil with 0.1 mol / L dilute hydrochloric acid (5 min) to remove the oxide layer on the surface. Rinse it repeatedly with deionized water and ethanol solution, and then dry it with nitrogen gas for later use.

[0052] 1,4-Benzenedithiol and tetraethyltetrafluoroborate ammonium were dissolved in a mixed solvent of ethanol and water (water volume fraction 50%), wherein the concentrations of 1,4-Benzenedithiol and tetraethyltetrafluoroborate ammonium were 2 mmol / L and 0.1 mol / L, respectively.

[0053] 100 ml of the electrolyte was injected into a three-electrode electrolytic cell. Ag / AgCl (saturated KCl solution) was used as the reference electrode, a copper sheet as the working electrode, and graphite as the counter electrode, with a 5 cm gap between the working and counter electrodes. After electrode connection, constant potential deposition was performed at a potential of 0.2 V for 60 minutes. After deposition, the electrolyte on the surface was rinsed off with ethanol to obtain a copper-thiol coordination polymer film with corrosion resistance.

[0054] Figure 9 The image shows the electrokinetic polarization curve of the passivation film obtained in this embodiment in a 0.1 mol / L H2SO4 solution. The results show that the passivated copper foil has a lower corrosion current density and can effectively suppress the corrosion of copper materials under acidic conditions.

[0055] Example 3 A method for preparing an in-situ corrosion-resistant thin film formed on a copper surface is provided, comprising the following steps: Cut uncoated copper foil rolls with a thickness of 30μm to a size of 4cm×200cm. Clean the copper foil with 0.1 mol / L dilute hydrochloric acid (10min) to remove the oxide layer on the surface. Rinse repeatedly with deionized water and ethanol solution, and then dry with nitrogen gas for later use.

[0056] Mercaptobenzimidazole and sodium fluoroborate were dissolved in acetonitrile, with concentrations of 10 mmol / L and 1 mol / L for mercaptobenzimidazole and sodium fluoroborate, respectively.

[0057] Inject the above 1000ml electrolyte into a three-electrode electrolytic cell, using Ag / Ag + A 10 mmol / L AgNO3 acetonitrile solution was used as the reference electrode, a copper foil roll as the working electrode, and a titanium sheet as the counter electrode, with a 10 cm gap between them. After electrode connection, constant potential deposition was performed at a potential of 0.5 V for 120 minutes. After deposition, the electrolyte on the surface was rinsed off with ethanol to obtain a copper-thiol coordination polymer film with corrosion resistance.

[0058] Figure 10 The image shows the electromotive force polarization curve of the passivation film in 0.1 mol / L NaOH solution. The results indicate that the passivated copper foil has a lower corrosion current density and can effectively suppress the corrosion of copper materials under alkaline conditions.

[0059] Example 4 A method for preparing an in-situ corrosion-resistant thin film formed on a copper surface is provided, comprising the following steps: The oxide layer on the surface of the copper wire (30 μm in diameter and 1 m in length) was removed by using hot acetic acid at 60 °C. The wire was then rinsed repeatedly with deionized water and ethanol solution, and then dried with nitrogen gas for later use.

[0060] 4-Mercaptophenol and tetrabutylfluoroborate ammonium were dissolved in a mixed solvent of isopropanol and water (water volume fraction 50%), wherein the concentrations of 4-mercaptophenol and tetrabutylfluoroborate ammonium were 10 mmol / L and 0.5 mol / L, respectively.

[0061] Electrolyte was injected into a three-electrode electrolytic cell. Ag / AgCl (saturated KCl solution) was used as the reference electrode, copper wire as the working electrode, and a platinum sheet as the counter electrode, with a 2 cm gap between the working and counter electrodes. After electrode connection, constant potential deposition was performed at a potential of 0.3 V for 5 minutes. After deposition, the electrolyte on the surface was rinsed off with ethanol to obtain a copper-thiol coordination polymer film with corrosion resistance.

[0062] Figure 11The image shows the electromotive force polarization curve of the passivation film after oxidation at 100℃ for 2 hours in 3.5% NaCl solution. The results indicate that the passivated copper wire still maintains good corrosion resistance and has a certain degree of high-temperature stability after high-temperature treatment.

[0063] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An anti-corrosion film formed in situ on the surface of metallic copper, characterized in that, The anti-corrosion film is a coordination polymer of copper ions and thiol compounds, formed in situ on the copper surface through anodic electrochemical deposition; wherein: The thickness of the anti-corrosion film is 3-8 nm; The specific process of the anodic electrochemical deposition is as follows: using metallic copper as the working electrode, a solution containing thiol compounds and supporting electrolyte as the electrolyte, and performing electrochemical deposition using a three-electrode system; The thiol compound is 1,4-benzenedithiol; the supporting electrolyte is at least one of sodium perchlorate, lithium perchlorate, sodium fluoroborate, tetraethyltetrafluoroborate, and tetrabutylfluoroborate. The concentration of the thiol compound is 1~10 mmol / L; the concentration of the supporting electrolyte is 0.01~1 mol / L; Electrochemical deposition is performed using a constant potential mode, where the electrode potential for electrochemical deposition relative to the open circuit is 0 V to +1.0 V.

2. The anti-corrosion film according to claim 1, characterized in that, The solvent in the electrolyte is an organic solvent, water, or a mixture thereof.

3. The anti-corrosion film according to claim 2, characterized in that, The organic solvent is selected from at least one of methanol, ethanol, isopropanol, cyclohexane, and acetonitrile.

4. A method for preparing an in-situ anti-corrosion film formed on the surface of metallic copper according to any one of claims 1-3, characterized in that, Includes the following steps: Using metallic copper as the working electrode and a solution containing thiol compounds and supporting electrolyte as the electrolyte, an electrochemical deposition is performed using a three-electrode system. This allows copper to undergo an oxidation reaction and coordinate with the thiol compounds in the electrolyte to polymerize in situ on the copper surface, forming a passivation film, thus obtaining an anti-corrosion film. The electrochemical deposition is performed using a constant potential mode, where the electrode potential relative to the open circuit is 0 V ~ +1.0 V.

5. The preparation method according to claim 4, characterized in that, Electrochemical deposition time is 1 to 120 minutes.

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