A method for passivating the surface of pure copper

Abstract

The present application belongs to the field of material surface treatment, and particularly relates to a surface passivation method of pure copper, comprising the following steps: performing pre-treatment on the pretreated sample, performing surface passivation on the sample after pre-treatment in a passivation solution, and generating a film layer capable of resisting external erosive ions on the surface of the pure copper and copper alloy after passivation treatment, so as to improve the breakdown potential and prolong the service life of the pure copper product; at least two passivation main agents, such as BTA derivatives and TTA, are required for the traditional pure copper passivation process, and the composition process is complex, and the compounding amount and ratio need to be considered; the passivation method of BTA + sulfosalicylic acid is adopted in the present application, and no BTA compounding agent is required, so as to solve the problems, and the operation is more simple and convenient; and the protection performance of the pure copper sample treated by the passivation process is improved, and the pure copper sample can resist Cl ‑ erosion in 3.5% NaCl solution for a long time, thereby providing guarantee for long-term operation of various pure copper samples in marine environment.

Description

Technical Field

[0001] This invention relates to the field of material surface treatment, and specifically to a method for surface passivation of pure copper. Background Technology

[0002] In modern industrial applications, copper and copper alloys are widely used in various high-end fields due to their unique physical and chemical properties, including but not limited to electronic information engineering, energy transmission, aerospace, military, and construction engineering. In particular, their excellent electrical and thermal conductivity make copper an indispensable material in electrical engineering and thermal management systems. However, although copper possesses a certain degree of corrosion resistance, in complex working environments, such as humid environments or environments containing corrosive ions, the surface of copper and copper alloys is still susceptible to corrosion, leading to performance degradation and even failure. Surface corrosion of copper and copper alloys not only affects the appearance of products but also severely impacts their electrical and thermal conductivity, further affecting the stability and service life of the entire equipment.

[0003] Currently, research and applications of surface treatment for copper and copper alloys mainly focus on physical deposition, chemical deposition, electrochemical deposition, micro-arc oxidation, and heat treatment. However, these traditional surface treatment processes have many limitations. For example, while physical evaporation deposition and chemical vapor deposition can improve the corrosion resistance of material surfaces, these methods often require high vacuum conditions, are complex, costly, and difficult to control the surface nanostructure of the treated material. Electrochemical deposition, although simple to operate and relatively low in cost, often fails to achieve the desired corrosion resistance and is prone to environmental pollution during the process. Micro-arc oxidation consumes a large amount of electricity during production, and its surface film often contains numerous pores, requiring post-treatment sealing, making the process cumbersome. Traditional heat treatment processes can cause material performance degradation, limiting their widespread application in certain fields. Furthermore, with increasingly stringent environmental protection requirements, this new surface treatment technology should also possess green and environmentally friendly characteristics, that is, while improving material performance, it should minimize its environmental impact to meet the needs of sustainable development.

[0004] Specifically, surface passivation technology for copper and copper alloys, if it can effectively improve the corrosion resistance of their surfaces without significantly affecting the material's electrical conductivity and thermal conductivity, will play a crucial role in enhancing the overall performance of the materials and extending their service life in demanding environments. Traditional pure copper passivation processes require at least two passivating agents, such as benzotriazole (BTA) derivatives and TTA, in combination. This process is complex, and the amount and ratio of these agents must be carefully considered. Therefore, researching and developing a new, environmentally friendly, efficient, and economical surface passivation technology for copper and copper alloys is of great significance for promoting the wider application of copper materials and their alloys in industrial fields. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the purpose of this invention is to provide a surface passivation method for pure copper. This method involves first performing a passivation pretreatment using an alkaline washing solution and an acid washing solution, followed by passivation treatment in a passivation solution. This process generates a film layer on the pure copper surface that can resist external corrosive ions, increasing the breakdown potential and extending the service life of pure copper products.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for passivating the surface of pure copper includes the following steps:

[0008] The pretreated pure copper samples were subjected to alkaline washing and acid washing. Alkaline washing was used to remove oil, and acid washing was used to promote the activation of the sample surface and promote the subsequent passivation reaction.

[0009] The samples after alkali washing and acid washing were placed in a passivation solution for surface passivation treatment. The passivation solution was a mixture of 4-20 g / L benzotriazole, 1-5 g / L sulfosalicylic acid, 10-30 mL hydrogen peroxide, and 0.5-2 g / L sodium dodecyl sulfate, with ethanol as the solvent.

[0010] In a preferred embodiment of the present invention, the passivation solution is a mixture composed of 12-20 g / L benzotriazole, 1-5 g / L sulfosalicylic acid, 10-30 mL hydrogen peroxide, and 1-2 g / L sodium dodecyl sulfate.

[0011] More preferably, the passivation solution is a mixture of 14–17.2 g / L benzotriazole, 1.30–2.30 g / L sulfosalicylic acid, 10–11 mL hydrogen peroxide, and 1–2 g / L sodium dodecyl sulfate.

[0012] In a preferred embodiment of the present invention, the passivation treatment temperature is 25–50°C.

[0013] Further optimization involves a passivation treatment temperature of 35–50°C.

[0014] In a preferred embodiment of the present invention, the passivation treatment time is 30 to 60 minutes.

[0015] In a preferred embodiment of the present invention, the alkaline washing solution is prepared from a Na2CO3 solution with a concentration of 50-60 g / L, a NaOH solution with a concentration of 5-6 g / L, and a Na3PO4 solution with a concentration of 50-60 g / L.

[0016] In a preferred embodiment of the present invention, the alkaline washing temperature is 40-50°C and the alkaline washing time is 5-10 minutes.

[0017] In a preferred embodiment of the present invention, the pickling solution is prepared from sulfuric acid and deionized water, and the volume fraction of sulfuric acid in the pickling solution is 10%.

[0018] In a preferred embodiment of the present invention, the pickling temperature is room temperature and the pickling time is 10-20 minutes.

[0019] In a preferred embodiment of the present invention, the pretreatment operation of the pure copper sample is to cut the sample and then polish it step by step, followed by cleaning and drying.

[0020] In a preferred embodiment of the present invention, the cleaning reagent solvent is ethanol or acetone.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention first uses alkaline and acidic washing solutions for passivation pretreatment, followed by passivation treatment. It employs a passivation method using benzotriazole (BTA) + sulfosalicylic acid, eliminating the need for a BTA passivation agent compound. This solves the problem of traditional pure copper passivation processes requiring at least two passivation agents, such as benzotriazole (BTA) derivatives and TTA, which are complex in composition and process, and require consideration of the compounding amount and ratio. Through passivation treatment, a corrosion-resistant film layer is obtained on the pure copper surface, improving the copper surface protection performance, significantly increasing the copper surface breakdown potential, and extending the service life of pure copper products. In the passivation system, BTA reacts with Cu, generating Cu-BTA, CuO, and Cu2O to provide protection to the substrate. The reaction process is as follows:

[0023] Cu + BTA = Cu(I) - BTA + H + +e

[0024] 2Cu(I)-BTA+H2O=Cu2O+2H + +BTA -

[0025] Cu(I)-BTA+H2O=CuO+H + +BTA.

[0026] 2. In the passivation solution of this invention, the addition of sulfosalicylic acid has two main functions: pure copper has poor chemical reactivity and is difficult to participate in chemical reactions; it relies solely on the H+ produced by the ionization of BTA itself. + It cannot drive copper to participate in the reaction, while sulfosalicylic acid is a multi-stage ionizer, with the first stage being complete ionization, providing H+. + This process lowers the dissolution potential of copper, promoting the loss of electrons by copper atoms to participate in film formation. On the other hand, according to the isoelectric point theory, sulfonate groups have a certain adsorption effect. The isoelectric point is the pH at which the number of positive and negative charges on the surface of the colloidal particles is equal. When the solution pH is higher than the isoelectric point, the colloidal particle surface is negatively charged; when the solution pH is lower than the isoelectric point, the colloidal particle surface is positively charged. Generally speaking, the colloidal particle surface carries either a positive or negative charge, but when the colloidal particle surface is uncharged, deposition is more likely to occur. In acidic environments, the surface of CuO and Cu2O crystal embryos carries a positive charge, and when sulfosalicylic acid loses an H atom... + Afterwards, it carries a negative charge and has a certain adsorption capacity, adsorbing onto the surface of the crystal embryo. The positive and negative charges neutralize each other, promoting the deposition behavior.

[0027] 3. Copper itself has relatively stable chemical properties. Adding a small amount of hydrogen peroxide solution can improve the oxidizing power of the passivation system, accelerate the dissolution process of copper by losing electrons, and promote the reaction. Sodium dodecyl sulfate (SDS) is a typical negatively charged corrosion inhibitor. In the passivation system, it is beneficial to neutralize the positively charged CuO and Cu2O preforms and promote the deposition process. Attached Figure Description

[0028] Figure 1 The diagram shows the potentiodynamic polarization curves of the copper surface passivation film and the substrate prepared in Example 1 of this invention.

[0029] Figure 2 XPS analysis image of the copper surface passivation film layer prepared in Example 1 of this invention;

[0030] Figure 3 These are scanning electron microscope images of the copper surface films prepared in Example 1 and Comparative Example 1 of the present invention; wherein, (a) is Comparative Example 1 and (b) is Example 1;

[0031] Figure 4 This is a cross-sectional scanning electron microscope image of the copper surface film prepared in Example 1 of the present invention;

[0032] Figure 5 EIS image of the copper surface film prepared in Example 1 of this invention after long-term immersion in 3.5% NaCl solution at 30°C;

[0033] Figure 6 The polarization curves of passivation films generated in the prior art are shown.

[0034] Figure 7The polarization curves of passivation films generated in the prior art are shown.

[0035] Figure 8 The image shows the potentiodynamic polarization curve of the copper surface passivation film prepared in Comparative Example 2 of this invention.

[0036] Figure 9 This is the polarization curve diagram of Comparative Example 8 of the present invention. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the data in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0039] "Passivation" has always been a broad concept. Some people believe that improved sample protection performance equates to passivation. However, for some samples, improved surface protection is merely the formation of a thin layer of corrosion products, which is loose and not dense, and cannot provide long-term protection. True passivation occurs when a dense oxide or other organic film forms close to the substrate, providing long-term protection. Traditional methods of testing treated samples using smoke and damp heat, relying on color changes to judge protective performance, are highly subjective and may introduce bias. The best way to measure passivation performance is through electrochemical methods, testing the sample's polarization curve to explore protective performance from a kinetic perspective.

[0040] like Figure 6 As shown, when a metal reaches a stable passivation state, a layer of corrosion-resistant oxide film or other organic film may form on the metal surface, called the passivation region. A significant characteristic of the polarization curve is the appearance of a current plateau region. Within this current plateau region, the metal moves at a very small current (i... p Dissolution occurs, i p This is called the sustaining passive current density. Therefore, the sustaining passive current density i p It is the current density necessary to maintain a stable passive state, i p The magnitude of represents the corrosion rate of passive metals. Typically, based on practical experience, i p ≤10 -4 A·cm-2 Only then can it be considered passivation, and it will appear. Figure 6 Features and satisfying i p Only under certain conditions can it be considered passivation.

[0041] In some metals within a corrosive system, the high corrosion rate leads to the formation of thick corrosion products. As the potential increases, corrosion intensifies, and the thickness of the corrosion products also increases significantly. These corrosion products exert a certain resistive polarization effect; therefore, the anodic polarization curve exhibits a large polarization rate, displaying characteristics of a pseudo-current plateau. Figure 7 As shown in the image. For this sample, severe corrosion was observed within a short period, therefore this is considered active dissolution rather than passivation.

[0042] Example 1

[0043] A method for passivating the surface of pure copper includes the following steps:

[0044] (1) Cut pure copper into 10*10*2mm pieces, polish them with SiC sandpaper of 240#, 400#, 600#, 1000# and 2000# in sequence, clean them with ethanol and then blow them dry.

[0045] (2) Prepare an alkaline washing solution with a composition of 50 g / L Na2CO3, 5 g / L NaOH, 50 g / L Na3PO4 and a volume of 1 L, and an acid washing solution with a composition of 10% sulfuric acid and a volume of 1 L. Perform alkaline washing and degreasing treatment at 50℃ for 4 min. After alkaline washing, rinse with deionized water and then perform acid washing treatment at room temperature for 20 min. After the treatment, take out the sample, rinse with deionized water and blow dry.

[0046] (3) Prepare a passivation solution consisting of 12 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 20 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS). To promote dissolution, add 50 mL of anhydrous ethanol. Prepare a passivation solution with a volume of 1 L and a passivation temperature of 38 °C. Place the sample obtained in step (2) into the passivation solution and control the reaction time to 30 min. After the reaction is completed, take out the sample, rinse it with deionized water, and blow it dry.

[0047] Example 2

[0048] A method for passivating the surface of pure copper includes the following steps:

[0049] (1) Cut pure copper into 10*10*2mm pieces, polish them with SiC sandpaper of 240#, 400#, 600#, 1000# and 2000# in sequence, clean them with ethanol and then blow them dry.

[0050] (2) Prepare an alkaline washing solution with a composition of 50 g / L Na2CO3, 5 g / L NaOH, 50 g / L Na3PO4 and a volume of 1 L, and an acid washing solution with a composition of 10% sulfuric acid and a volume of 1 L. Perform alkaline washing and degreasing treatment at 50℃ for 4 min. After alkaline washing, rinse with deionized water and then perform acid washing treatment at room temperature for 20 min. After the treatment, take out the sample, rinse with deionized water and blow dry.

[0051] (3) Prepare a passivation solution consisting of 12 g / L benzotriazole (BTA), 1 g / L sulfosalicylic acid, 30 mL hydrogen peroxide, and 1 g / L sodium dodecyl sulfate (SDS). To promote dissolution, add 50 mL of anhydrous ethanol. Prepare a passivation solution with a volume of 1 L and a passivation temperature of 50 °C. Place the sample obtained in step (2) into the passivation solution and control the reaction time to 30 min. After the reaction is completed, take out the sample, rinse it with deionized water, and blow it dry.

[0052] Example 3

[0053] A method for passivating the surface of pure copper includes the following steps:

[0054] (1) Cut pure copper into 10*10*2mm pieces, polish them with SiC sandpaper of 240#, 400#, 600#, 1000# and 2000# in sequence, clean them with ethanol and then blow them dry.

[0055] (2) Prepare an alkaline washing solution with a composition of 50 g / L Na2CO3, 5 g / L NaOH, 50 g / L Na3PO4 and a volume of 1 L, and an acid washing solution with a composition of 10% sulfuric acid and a volume of 1 L. Perform alkaline washing and degreasing treatment at 50℃ for 4 min. After alkaline washing, rinse with deionized water and then perform acid washing treatment at room temperature for 20 min. After the treatment, take out the sample, rinse with deionized water and blow dry.

[0056] (3) Prepare a passivation solution consisting of 4 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 20 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS). To promote dissolution, add 50 mL of anhydrous ethanol. Prepare a passivation solution with a volume of 1 L and a passivation temperature of 50 °C. Place the sample obtained in step (2) into the passivation solution and control the reaction time to 30 min. After the reaction is completed, take out the sample, rinse it with deionized water, and blow it dry.

[0057] Example 4

[0058] A method for passivating the surface of pure copper includes the following steps:

[0059] (1) Cut pure copper into 10*10*2mm pieces, polish them with SiC sandpaper of 240#, 400#, 600#, 1000# and 2000# in sequence, clean them with ethanol and then blow them dry.

[0060] (2) Prepare an alkaline washing solution with a composition of 40 g / L Na2CO3, 5 g / L NaOH, 40 g / L Na3PO4 and a volume of 1 L, and an acid washing solution with a composition of 10% sulfuric acid solution and a volume of 1 L. Perform alkaline washing and degreasing treatment at 50℃ for 4 min. After alkaline washing, rinse with deionized water and then perform acid washing treatment at room temperature for 20 min. After the treatment, take out the sample, rinse with deionized water and blow dry.

[0061] (3) Prepare a passivation solution consisting of 20 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 30 mL hydrogen peroxide, and 1 g / L sodium dodecyl sulfate (SDS). To promote dissolution, add 50 mL of anhydrous ethanol. Prepare a passivation solution with a volume of 1 L and a passivation temperature of 37.5 °C. Place the sample obtained in step (2) into the passivation solution and control the reaction time to 30 min. After the reaction is completed, take out the sample, rinse it with deionized water, and blow it dry.

[0062] Example 5

[0063] The preparation method is the same as in Example 1, except that the composition of the passivation solution is replaced with: 12 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 20 mL hydrogen peroxide, and 1 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature is 25 °C.

[0064] Example 6

[0065] The preparation method is the same as in Example 1, except that the composition of the passivation solution is replaced with: 20 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 10 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature is 40 °C.

[0066] Example 7

[0067] The preparation method is the same as in Example 1, except that the composition of the passivation solution is replaced with: 12 g / L benzotriazole (BTA), 1 g / L sulfosalicylic acid, 30 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature is 40 °C.

[0068] Example 8

[0069] The preparation method is the same as in Example 1, except that the composition of the passivation solution is replaced with: 12 g / L benzotriazole (BTA), 1 g / L sulfosalicylic acid, 10 mL hydrogen peroxide, and 1 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature is 25 °C.

[0070] Example 9

[0071] The preparation method is the same as in Example 1, except that the composition of the passivation solution is replaced with: 12 g / L benzotriazole (BTA), 5 g / L sulfosalicylic acid, 30 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature is 37.5 °C.

[0072] Example 10

[0073] The preparation method is the same as in Example 1, except that the composition of the passivation solution is replaced with: 12 g / L benzotriazole (BTA), 5 g / L sulfosalicylic acid, 30 mL hydrogen peroxide, and 1 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature is 25 °C.

[0074] Comparative Example 1

[0075] A method for passivating the surface of pure copper includes the following steps:

[0076] (1) Cut pure copper into 10*10*2mm pieces, polish them with SiC sandpaper of 240#, 400#, 600#, 1000# and 2000# in sequence, clean them with ethanol and then blow them dry.

[0077] (2) Prepare an alkaline washing solution with a composition of 40 g / L Na2CO3, 5 g / L NaOH, 40 g / L Na3PO4 and a volume of 1 L, and an acid washing solution with a composition of 10% sulfuric acid and a volume of 1 L. Perform alkaline washing and degreasing treatment at 50℃ for 4 min. After alkaline washing, rinse with deionized water and then perform acid washing treatment at room temperature for 20 min. After the treatment, take out the sample, rinse with deionized water and blow dry.

[0078] Comparative Example 2

[0079] A method for passivating the surface of pure copper includes the following steps:

[0080] (1) Cut pure copper into 10*10*2mm pieces, polish them with SiC sandpaper of 240#, 400#, 600#, 1000# and 2000# in sequence, clean them with ethanol and then blow them dry.

[0081] (2) Prepare an alkaline washing solution consisting of 50 g / L Na2CO3, 5 g / L NaOH, and 50 g / L Na3PO4, with a volume of 1 L; prepare an acid washing solution consisting of a 10% sulfuric acid solution, with a volume of 1 L. Perform alkaline washing and degreasing treatment at 50℃ for 4 min, rinse with deionized water after alkaline washing, and then perform acid washing treatment at room temperature for 20 min. After the acid washing is completed, remove the sample, rinse with deionized water, and blow dry.

[0082] (3) Prepare a passivation solution consisting of 4 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 30 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS). To promote dissolution, add 50 mL of anhydrous ethanol, and prepare a passivation solution with a volume of 1 L. The passivation temperature is 37.5 °C. Place the sample obtained in step (2) into the passivation solution and control the reaction time to 30 min. After the reaction is complete, remove the sample, rinse it with deionized water, and dry it.

[0083] The polarization curves of the sample in Comparative Example 2 were tested. Both the anode and cathode reactions were simulated, and the corrosion current was reduced. However, the polarization curves did not show passivation characteristics. The sample surface was only protected by the corrosion products generated in the passivation solution, rather than a true passivation film.

[0084] Comparative Example 3

[0085] The preparation method was the same as that of Comparative Example 2, except that the composition of the passivation solution was replaced with: 4 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 20 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature was 25 °C.

[0086] Comparative Example 4

[0087] The preparation method was the same as that of Comparative Example 2, except that the composition of the passivation solution was replaced with: 4 g / L benzotriazole (BTA), 5 g / L sulfosalicylic acid, 20 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature was 37.5 °C.

[0088] Comparative Example 5

[0089] The preparation method was the same as that of Comparative Example 2, except that the composition of the passivation solution was replaced with: 4 g / L benzotriazole (BTA), 1 g / L sulfosalicylic acid, 20 mL hydrogen peroxide, and 1 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature was 37.5 °C.

[0090] Comparative Example 6

[0091] The preparation method was the same as that of Comparative Example 2, except that the composition of the passivation solution was replaced with: 4 g / L benzotriazole (BTA), 3 g / L sulfosalicylic acid, 10 mL hydrogen peroxide, and 2 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature was 37.5 °C.

[0092] Comparative Example 7

[0093] The preparation method was the same as that of Comparative Example 2, except that the composition of the passivation solution was replaced with: 4 g / L benzotriazole (BTA), 5 g / L sulfosalicylic acid, 20 mL hydrogen peroxide, and 1 g / L sodium dodecyl sulfate (SDS), and the passivation reaction temperature was 37.5 °C.

[0094] Comparative Example 8

[0095] In Comparative Example 8, compared with the unpassivated sample, curves b and c show a tendency for the cathode to be suppressed, while no obvious change is observed in the anode. The anode polarization curve under this passivation method does not show obvious passivation characteristics, and it is not that oxides or other anti-slip films are generated on the sample surface. The sample surface still undergoes anodic dissolution.

[0096] Results Analysis

[0097] Figure 1 The potentiodynamic polarization curves of the copper surface film prepared in Example 1 of this invention and the substrate of Comparative Example 1 are shown below. Figure 1 As shown, the pure copper surface exhibits obvious passivation characteristics after passivation, with a breakdown potential of 0.213V and a passivation current of 4.62μA / cm. 2 Compared to a bare pure copper sample, the corrosion current decreased from 8.70 μA / cm. 2 Decreased to 1.03 μA / cm 2 The protective performance has been significantly improved.

[0098] Figure 2 The figure shows an XPS analysis image of the copper surface film prepared in Example 1 of this invention. As shown, the Cu compounds in the surface film are mainly CuO, Cu₂O, and Cu-BTA. Cu-BTA is a complex product of the reaction between the pure copper substrate and BTA, covering the substrate surface. Meanwhile, the metal oxides effectively resist external corrosive ions such as Cl₂. - This improves the protective performance of the substrate.

[0099] Figure 3 These are surface electron microscope (SEM) images of the copper surface films prepared in Example 1 and Comparative Example 1 of the present invention, wherein (a) is Comparative Example 1 and (b) is Example 1. Figure 3 As shown in (b), compared to after only alkaline washing and acid washing. Figure 3 (a) Compared to Example 1 Figure 3 (b) A uniform film layer is present on the copper surface.

[0100] Figure 4 This is a cross-sectional electron microscope scan of the copper surface film prepared in Example 1 of the present invention. The film thickness is approximately 150 nm.

[0101] Figure 5 The image shows the EIS diagram of the copper surface film prepared in Example 1 of this invention after long-term immersion in a 3.5% NaCl solution at 30°C. Figure 5 As shown, Figure 5 (a) and (b) are pure copper samples. Figure 5 (c) and (d) are the passivated samples from Example 1, and (e) is the result of statistical analysis of the R values ​​of the two samples after 20 days of immersion using a fitting circuit R(Q(R(QR))). p Numerical values. After long-term immersion in 3.5% NaCl solution, the sample surface after passivation treatment in Example 1 still maintained better protective performance compared to the pure copper sample.

[0102] Table 1 Comparison of corrosion resistance of passivation systems in Examples 1-10 and Comparative Examples 2-7

[0103]

[0104]

[0105] Table 1 compares the corrosion resistance of the passivation systems of Examples 1-10 and Comparative Examples 2-7. It can be seen that pure copper in the passivation solution systems of Examples 1-10 all showed obvious passivation characteristics, while pure copper in the passivation solution ratios of Comparative Examples 2-7 did not undergo passivation.

[0106] In summary, this invention first uses alkaline and acidic washing solutions for passivation pretreatment, followed by passivation treatment. It employs a passivation method using BTA + sulfosalicylic acid, eliminating the need for BTA compounding agents. This solves the problem of complex composition and processes in traditional pure copper passivation processes, which require compounding of BTA derivatives such as TTA as the main passivating agent. The passivation treatment results in a corrosion-resistant film layer on the pure copper surface, improving its protective properties, significantly increasing the surface breakdown potential, and extending the service life of pure copper products.

[0107] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0108] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for surface passivation of pure copper, characterized in that, Includes the following steps: The pretreated pure copper samples were subjected to alkaline washing and acid washing. The alkaline washing solution was prepared by 50-60 g / L Na2CO3 solution, 5-6 g / L NaOH solution and 50-60 g / L Na3PO4 solution. The acid washing solution was prepared by sulfuric acid and deionized water, and the volume fraction of sulfuric acid in the acid washing solution was 10%. The samples after alkaline washing and acid washing were placed in a passivation solution for surface passivation treatment. The passivation solution was a mixture of 12-20 g / L benzotriazole, 1-5 g / L sulfosalicylic acid, 10-30 mL hydrogen peroxide, 0.5-2 g / L sodium dodecyl sulfate, and ethanol, wherein ethanol was the solvent in the mixture. The passivation temperature is 25–50℃, and the passivation time is 30–60 min.

2. The method for surface passivation of pure copper according to claim 1, characterized in that, The alkaline washing temperature is 40-50℃, and the alkaline washing time is 5-10 minutes.

3. The surface passivation method for pure copper according to claim 1, characterized in that, Pickling temperature is room temperature, and pickling time is 10-20 minutes.

4. The surface passivation method for pure copper according to claim 1, characterized in that, The pretreatment process for pure copper samples involves cutting the sample, grinding it step by step, and then cleaning and drying it.

5. The surface passivation method for pure copper according to claim 4, characterized in that, The cleaning reagent solvent is ethanol or acetone.

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