Passivation solution as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of copper surface treatment, and particularly provides a passivation solution and a preparation method and application thereof. The passivation solution is prepared from 4.5%-10.0% of a film agent, 3.0%-6.5% of an auxiliary film-forming agent, 0.5%-15.0% of an oxidizing agent, 2.5%-6.5% of boron powder and the balance deionized water. The effective components of the film-forming agent are a benzotriazole derivative and tolyl triazole, the effective components of the auxiliary film-forming agent are cerous nitrate and lanthanum nitrate, and the effective component of the oxidizing agent is sodium hypochlorite or hydrogen peroxide; the problems that an existing passivation solution is complex, the production cost is high, the time of the passivation solution is too long, the speed requirement of a production line cannot be met, the passivation technological process is complex, part of performance cannot meet the requirement, and industrial application is difficult to achieve are solved, the passivation solution is easy to prepare, the passivation process is simple, the passivation time is short, and the speed requirement of the technological generation process is met.

Description

Technical Field

[0001] The invention belongs to the technical field of copper surface treatment, and in particular relates to a passivation solution and a preparation method and application thereof. Background Art

[0002] Copper and alloys with copper as the main component have good electrical conductivity, thermal conductivity and stability, so they are used in the heating core of cables. During the production and storage process of cables, there is a problem of surface oxidation of the copper core, which has a great impact on the subsequent thermal and electrical conductivity of the cable.

[0003] The copper core of the cable is exposed to the air. Natural oxidation in the air and reaction with acid ions in a specific environment will cause the copper surface to produce brown-red or blue-green oxidation products, namely verdigris, the main components of which are Cu2O, Cu x So4(OH) y Basic copper sulfate. Passivation is a metal surface treatment technology, which is to increase the chemical reaction or electroplating to form a dense film on the surface of the metal substrate, which improves the corrosion resistance and oxidation resistance of the substrate to a certain extent.

[0004] Chromic acid and chromate are commonly used in the passivation process of industrial production. Although the process is relatively simple and mature, and the passivation effect is excellent, due to the use of chromate, hexavalent chromium exists in its aqueous solution, which is a strong carcinogen. Long-term contact and use will cause serious consequences to the human body. At the same time, it is extremely unfriendly to the environment and will cause serious environmental pollution. In today's world where environmental protection and greenness are strongly advocated, the chromium-free passivation formula of copper and its alloys has great research value.

[0005] After years of research by scientists, phytic acid system passivation liquid, molybdate system passivation liquid, silicate system passivation liquid and rare earth salt system passivation liquid have been proposed for chromium-free passivation liquid. However, these traditional copper chromium-free passivation liquids can only achieve 50%-70% of the passivation effect of chromate passivation liquid. At the same time, there are also problems such as long passivation time, harsh passivation conditions and complex passivation process. In the process of studying chromium-free passivation liquid for copper core of heating cable, we found that the passivation liquid on the market currently has the following problems: (1) The passivation solution is complex and the production cost is high; the passivation effect does not meet the requirements under low-cost conditions; (2) The passivation time is too long and cannot meet the speed requirements of the production line; (3) The passivation process is complicated, some performance characteristics do not meet the requirements, and it is difficult to achieve industrial application.

[0006] Therefore, in view of the problems existing in traditional chromate system passivation solution, chromium-free system passivation solution and existing copper passivation solution system and passivation treatment method thereof, a new passivation solution and passivation treatment method with low cost, high efficiency, meeting industrial production requirements, good passivation effect and green environmental protection is developed, which is of great significance for promoting the development and popularization of surface passivation treatment of copper and its alloys.

[0007] The Chinese patent document with publication number CN106756962A discloses a copper alloy surface passivation process, including mechanical grinding-electrochemical polishing-chemical degreasing-80°C hot water washing-cold air drying-mixed acid washing-80°C hot water washing-cold air drying-passivation liquid roller coating-distilled water washing-cold air drying; the passivation liquid includes benzotriazole (BTA) 3-10g / L, citric acid 10~20g / L, rare earth salt 0.2~1g / L, sulfosalicylic acid 1~5g / L, sodium dodecyl sulfate 1~3g / L, film-forming promoter 1-2g / L, oxidant 1-2g / L; the passivation roller coating time is 3min, and the processing temperature is 50-60°C. The passivation in this document still has the problems of complex process, long passivation time, and large amount of water for multiple rinsing. Summary of the invention

[0008] The invention provides a passivation solution and a preparation method and application thereof, aiming to overcome the problems in the prior art of complex passivation solution, high production cost, long passivation time, inability to meet the speed requirements of the production line, complex passivation process, some performance failing to meet the requirements, and difficulty in realizing industrial application.

[0009] To this end, the present invention provides a passivation solution, which is composed of the following components in the following mass percentages: 4.5-10.0% of a film-forming agent, 3.0-6.5% of an auxiliary film-forming agent, 0.5-15.0% of an oxidant, 2.5-6.5% of boron powder, and the rest is deionized water; the effective components of the film-forming agent are benzotriazole derivatives and tolyltriazole, the effective components of the auxiliary film-forming agent are cerium nitrate and lanthanum nitrate, and the effective component of the oxidant is sodium hypochlorite or hydrogen peroxide. Preferably, the film-forming agent is a mixture of benzotriazole derivatives, tolyltriazole and deionized water, wherein the mass ratio of the benzotriazole derivatives to tolyltriazole is 3-10:4-9.5.

[0010] Preferably, the mass ratio of the cerium nitrate to the lanthanum nitrate is 0.5-1.5:0.5-1.5.

[0011] Preferably, a method for preparing a passivation solution according to any one of the above, comprises the following steps: S1.1, add the formulated amount of benzotriazole derivative and tolyltriazole into deionized water, and stir evenly to form solution A; S1.2. Add the formulated amount of boron powder into solution A, heat the mixture to target temperature 1, stir evenly and completely dissolve the boron powder; S1.3. Evenly mix the auxiliary film-forming agent and deionized water in the formula amount, and then add the evenly mixed solution and the oxidant into the solution after the boron powder is completely dissolved to form solution B. After solution B is evenly stirred and fully reacted at target temperature 2, a passivation solution is obtained.

[0012] A method for passivating a copper inner core of a cable using a passivation solution according to any one of the above, comprising the following steps: S2.1. First, the copper sample is pickled and surface pretreated to remove pollutants and oxide layers on the surface of the copper sample; S2.2, placing the pretreated copper sample into the passivation solution, the passivation temperature is 25-70°C, the pH value is 4-10, and the passivation treatment time is 30-150s; S2.3, drying the copper sample treated in step S2.2 at a temperature of 60-100° C. to obtain a passivation film on the surface of the copper sample, thus completing the passivation.

[0013] Preferably, step S2.2 requires that the copper sample be completely immersed during passivation and stirred using ultrasonic vibration.

[0014] Preferably, the surface pretreatment includes grinding and pickling.

[0015] Preferably, the pickling requires that the copper sample be completely immersed and continuously swung.

[0016] Preferably, an acetic acid solution is used during the pickling; Preferably, in the acetic acid solution, the mass ratio of acetic acid to water is 1-3:15-25.

[0017] Beneficial effects of the present invention: 1. The passivation solution provided by the present invention is composed of the following components in the following mass percentage: film former 4.5-10.0%, auxiliary film former 3.0-6.5%, oxidant 0.5-15.0%, boron powder 2.5-6.5%, and the rest is deionized water, replacing the traditional chromate system passivation solution, chromium-free system passivation solution and traditional copper passivation solution, using benzotriazole derivatives and tolyltriazole as film formers, greatly improving the uniformity and density of the copper surface passivation film, thereby improving the high temperature oxidation resistance and corrosion resistance of the copper surface, and having non-toxicity and pollution-free, and the cost is only 65% ​​of the same series of passivation solutions under the same passivation effect. The passivation solution is easy to configure, the passivation process is simple, the passivation time is short, which is 30~150s, the effect is good, and the passivation time is 1.5 times faster than the same series of products. Meet the speed requirements of the process generation process.

[0018] 2. The preparation method and application of the passivation solution provided by the present invention. The passivation film layer obtained by the preparation method of the present invention has a dense and uniform structure, and has little effect on the electrical conductivity and thermal conductivity of the copper sample itself. At the same time, due to the addition of boron powder, the oxide layer has excellent corrosion resistance, friction resistance and high-temperature oxidation resistance. The mass loss in the neutral salt spray test is only 30% of the same series of passivation solutions on the market.

[0019] 3. The passivation solution and its preparation method and application provided by the present invention have a short process flow, do not require multiple rinsing in the traditional passivation process, save a lot of water resources, and save more than about 50% of water resources per ton of copper core produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described in detail below with reference to the accompanying drawings.

[0021] Figure 1 is the surface super depth of field morphology of the passivation film after the copper sample is treated in Example 1; Figure 2 This is an ultra-depth-of-field morphology image of the surface after corrosion when the nitric acid solution is dripped onto the surface of the passivated copper sample in Example 1. DETAILED DESCRIPTION

[0022] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0023] A passivation solution is composed of the following components in the following mass percentages: 4.5-10.0% of a film former, 3.0-6.5% of an auxiliary film former, 0.5-15.0% of an oxidant, 2.5-6.5% of boron powder, and the remainder being deionized water; the effective components of the film former are benzotriazole derivatives and tolyltriazole, the effective components of the auxiliary film former are cerium nitrate and lanthanum nitrate, and the effective component of the oxidant is sodium hypochlorite or hydrogen peroxide.

[0024] Specifically, the Irgamet39 (benzotriazole derivative) and TTAH (tolyltriazole) are film-forming agents, which react with the substrate to form a passivation film or form an adsorption film on the surface to achieve corrosion inhibition and form a passivation film on the metal surface; the cerium nitrate and lanthanum nitrate are auxiliary film-forming agents, which have a certain corrosion inhibition effect or a composite effect with the film-forming agent to improve the passivation effect; the B powder will adhere to the inside of the oxide layer. When the environment contains chloride ions, the dissolved boron can fix the chloride ions, thereby hindering the destruction of the passivation film. Sodium hypochlorite and hydrogen peroxide (H2O2) are oxidants, and their main function is to oxidize copper into an ionic state and promote passivation. The above solvents work together to react with copper ions to form a dense and uniform passivation film, which has excellent corrosion resistance, high temperature oxidation resistance and good electrical conductivity. The passivation solution of the present invention has the characteristics of being non-toxic and pollution-free, and having a small number of additives.

[0025] The passivation mechanism of the passivation solution is as follows: first, the copper matrix is ​​oxidized and dissolved to generate CuO and Cu2O. Secondly, the film-forming agents Irgamet39 (benzotriazole derivative) and TTAH (tolyltriazole) react with copper ions to generate Cu polymers; at the same time, the B powder dissolves and adsorbs on the surface of the Cu polymer, and the acid radical ions in the auxiliary film-forming agents cerium nitrate and lanthanum nitrate react with the remaining copper ions to generate compounds to improve the passivation effect; finally, the polymer film undergoes spontaneous reorganization to reach the most stable state, accompanied by the diffusion of CuO and Cu2O particles in the gaps to form a dense passivation film.

[0026] Preferably, the film-forming agent is a mixture of benzotriazole derivatives, tolyltriazole and deionized water, wherein the mass ratio of the benzotriazole derivatives to tolyltriazole is 3-10:4-9.5.

[0027] Preferably, the mass ratio of the cerium nitrate to the lanthanum nitrate is 0.5-1.5:0.5-1.5.

[0028] Specifically, the passivation film prepared within the mass ratio range of the above-mentioned optimized combination has excellent corrosion resistance and high-temperature oxidation resistance. When the content of the effective components of the above-mentioned passivation solution is lower than the above-mentioned content range, it will lead to incomplete reaction and incomplete oxidation film; higher than the above-mentioned content range will cause the components of the solution itself to destroy or corrode the oxidation film, resulting in uneven oxidation film; when the content of the effective components of the above-mentioned passivation solution is higher or lower than the above-mentioned content range, it will reduce the passivation effect of copper and its alloys, affecting its oxidation resistance and corrosion resistance. For example, when the content of the TTAH is higher than the above-mentioned content range, the oxidation film will be unevenly generated, the surface color of the sample will be uneven, and the antioxidant performance will be reduced.

[0029] Preferably, a method for preparing a passivation solution according to any one of the above, comprises the following steps: S1.1, add the formulated amount of benzotriazole derivative and tolyltriazole into deionized water, and stir evenly to form solution A; S1.2. Add the formulated amount of boron powder to solution A, heat the mixture to target temperature 1, stir evenly and completely dissolve the boron powder; preferably, the target temperature 1 is 60°C; S1.3. Add the auxiliary film-forming agent and oxidant in the formulated amount to the solution in which the boron powder is completely dissolved to form solution B. Stir solution B evenly and allow it to react fully at target temperature 2 to obtain a passivation solution.

[0030] Preferably, the target temperature 2 is 50-60° C., and solution B is stirred at a frequency of 90 Hz using ultrasonic vibration for 3-6 minutes.

[0031] The preparation method of the invention is simple.

[0032] Preferably, a method for passivating a copper inner core of a cable using the passivation solution described in any one of the above items comprises the following steps: S2.1. First, the copper sample is pickled and surface pretreated to remove pollutants and oxide layers on the surface of the copper sample; S2.2, placing the pretreated copper sample into the passivation solution, the passivation temperature is 25-70°C, the pH value is 4-10, and the passivation treatment time is 30-150s; S2.3, drying the copper sample treated in step S2.2 at a temperature of 60-100° C. to obtain a passivation film on the surface of the copper sample, thus completing the passivation.

[0033] Specifically, the copper passivation film obtained by the above passivation process for the copper inner core of the cable is of good quality, uniform and dense, and has no surface defects such as cracks, bubbles and pores. When the values ​​of the process parameters used are higher or lower than the above process parameter range, the quality of the passivation film of the sample will be significantly negatively affected. For example, if the value of the passivation temperature exceeds the passivation temperature range of the above process, it will be difficult to adsorb and form a film, and if the pH value used exceeds or is lower than the above solution pH range, bubbles will appear on the surface of the passivation film.

[0034] The passivation treatment method of the present invention has a short process flow, does not require multiple rinsing in the traditional passivation process, saves a large amount of water resources, and saves more than about 50% of water resources per ton of copper core produced.

[0035] Preferably, step S2.2 requires that the copper sample be completely immersed during passivation and stirred using ultrasonic vibration.

[0036] Specifically, complete immersion ensures that the copper sample is fully acidified, and ultrasonic vibration stirring is used to improve the acidification efficiency.

[0037] Preferably, the surface pretreatment includes grinding and pickling.

[0038] Preferably, the pickling requires that the copper sample be completely immersed and continuously swung.

[0039] Specifically, the sample surface needs to be pickled and polished before passivation, and a full immersion passivation method is used. At the same time, a heating furnace, a stirring rod and ultrasonic stirring are required to ensure that the reaction is fully carried out. The passivation solution makes the copper sample surface obtain a uniform and dense passivation film, which plays an anti-oxidation and corrosion resistance as well as a conductive role, meeting the needs of the heating cable during use.

[0040] Preferably, an acetic acid solution is used during the pickling; Specifically, acetic acid pickling can effectively remove the oxide layer and rust on the metal surface, restore the metal surface to its original state, and ensure the quality and effect of subsequent processing.

[0041] Preferably, in the acetic acid solution, the mass ratio of acetic acid to water is 1-3:15-25.

[0042] Specifically, the pickling effect is best when the acetic acid solution is used within this range.

[0043] Embodiment 1: A passivation solution is composed of the following components in terms of mass: 8 g of a benzotriazole derivative, 6 g of tolyltriazole, 3 g of cerium nitrate, 3 g of lanthanum nitrate powder, 5 g of boron powder, 20 ml of 30% hydrogen peroxide (22.2 g), and 1000 ml of deionized water.

[0044] Finally, 3 g of cerium nitrate and 3 g of lanthanum nitrate powder were weighed, added to 500 ml of deionized water, and stirred thoroughly to form a mixed solution. 500 ml of the mixed solution and 20 ml of 30% hydrogen peroxide were added to the solution A through a drainage rod, and stirred at 90 Hz for 4-10 minutes by ultrasonic vibration to form a solution B to obtain the desired passivation solution.

[0045] The preparation method of the passivation solution comprises the following steps: S1.1, add 8 g of benzotriazole derivative powder into 500 mL of deionized water, stir evenly, then slowly add 6 g of tolyltriazole powder into the benzotriazole derivative solution, stir mechanically to mix well, and obtain solution A; S1.2. Use a heating furnace to keep the temperature of solution A at 50-60°C, add 5g of boron powder into solution A, stir evenly and dissolve the boron powder completely; S1.3. Add 3g of cerium nitrate and 3g of lanthanum nitrate powder into 500ml of deionized water and stir thoroughly to prepare solution B. Add 500ml of solution B and 20ml of 30% hydrogen peroxide through a drainage rod into the solution after the boron powder is completely dissolved. Stir at 90Hz for 4-10 minutes by ultrasonic vibration to form solution B to obtain the desired passivation solution.

[0046] The passivation of the copper inner core of the cable using the passivation solution of this embodiment includes the following steps: S2.1. First, pickle and pre-treat the pure copper sample by pickling it in a 10% acetic acid solution for 15 seconds, then soak and clean it in deionized water, and then fully grind and observe the pure copper sample to ensure that the pollutants and oxide layer on the surface of the pure copper sample are removed; S2.2, the pretreated pure copper sample was placed in the passivation solution, TTA passivation solution 1 and BTA passivation solution 2 on the market, respectively, the passivation temperature was 60 ° C, the pH value was 6, and the passivation treatment time was 90s; S2.3, drying the pure copper sample treated in step S2.2 at a temperature of 70°C, and obtaining a passivation film (such as Figure 1 As shown), passivation is completed.

[0047] Note that during the passivation process, the passivation solution of this embodiment is consistent with the passivation process of TTA passivation solution 1 and BTA passivation solution 2 on the market, including the initial state of the sample, passivation time, passivation temperature and passivation method.

[0048] The samples passivated with three kinds of passivation solutions were subjected to salt water immersion test analysis. The salt water immersion test can relatively accurately and truly reflect the corrosion resistance of the passivation film itself. The steps are to immerse it in 5% NaCl solution for 48 hours, rinse and dry the corrosion products of the sample, and then weigh them. The corrosion weight loss or corrosion weight loss rate of the sample is calculated by the mass difference before and after the experiment. The specific values ​​are as follows in Table 1: Table 1 Corrosion weight loss of pure copper samples

[0049] It can be seen from the salt water immersion experiment that the passivation solution of this embodiment greatly improves the corrosion resistance of the sample when passivating pure copper, and the corrosion weight loss rate is only 30% to 50% of the products on the market.

[0050] The passivation of the copper inner core (red copper material) of the cable using the passivation solution of this embodiment includes the following steps: S2.1. First, pickle and pre-treat the copper sample by pickling it in a 10% acetic acid solution for 20 seconds, then soak and clean it in deionized water, and then fully grind and observe the copper sample to ensure that the pollutants and oxide layer on the surface of the copper sample are removed; S2.2, the pretreated copper sample was placed in the passivation solution, TTA passivation solution 1 and BTA passivation solution 2 on the market, respectively, the passivation temperature was 70°C, the pH value was 7, and the passivation treatment time was 120s; S2.3. Dry the copper sample treated in step S2.2 at 70° C. to obtain a passivation film on the surface of the copper sample, thus completing the passivation.

[0051] The samples passivated with three kinds of passivation solutions were subjected to nitric acid spot test analysis, which can quickly detect the corrosion resistance of the samples. The steps are to drop 25% nitric acid solution on the surface of the passivated sample, corrode for 20 seconds, rinse and dry, and observe the changes in surface morphology (such as Figure 2 As shown in Table 2: Table 2 Passivation solution corrosion results

[0052] It can be quickly and obviously seen from the nitric acid dripping experiment that after the passivation solution of the present invention passivates red copper, the corrosion resistance of the sample is greatly improved. When the nitric acid with a concentration of 25% is dripped and corroded for 20 seconds, there is almost no large blackboard and serious discoloration on the surface. The effect is better than the copper passivation solution on the market and almost reaches the effect of the chromate passivation solution.

[0053] Embodiment 2: A passivation solution is composed of the following components in terms of mass: 6 g of a benzotriazole derivative, 14 g of tolyltriazole, 3 g of cerium nitrate, 9 g of lanthanum nitrate powder, 12 g of boron powder, 24 ml of 30% sodium hypochlorite (30 g), and 1000 ml of deionized water.

[0054] The preparation method of the passivation solution comprises the following steps: S1.1, add 6 g of benzotriazole derivative powder into 500 mL of deionized water, stir evenly, then slowly add 14 g of tolyltriazole powder into the benzotriazole derivative solution, stir mechanically to mix well, and obtain solution A; S1.2. Use a heating furnace to keep the temperature of solution A at 50-60°C, add 12g of boron powder into solution A, stir evenly and dissolve the boron powder completely; S1.3. Add 3g of cerium nitrate and 9g of lanthanum nitrate powder into 500ml of deionized water and stir thoroughly to prepare solution B. Add 500ml of solution B and 20ml of 30% hydrogen peroxide into the solution after the boron powder is completely dissolved through a drainage rod. Stir at 90Hz for 5-10 minutes by ultrasonic vibration to form solution B to obtain the desired passivation solution.

[0055] The passivation of the copper inner core of the cable using the passivation solution of this embodiment includes the following steps: S2.1. First, pickle and pre-treat the pure copper sample by pickling it in a 12% acetic acid solution for 15 seconds, then soak and clean it in deionized water, and then fully grind and observe the pure copper sample to ensure that the pollutants and oxide layer on the surface of the pure copper sample are removed; S2.2, the pretreated pure copper sample was placed in the passivation solution, TTA passivation solution 1 and BTA passivation solution 2 on the market, respectively, the passivation temperature was 60 ° C, the pH value was 10, and the passivation treatment time was 30s; S2.3, drying the pure copper sample treated in step S2.2 at a temperature of 100° C. to obtain a passivation film on the surface of the pure copper sample, thus completing the passivation.

[0056] Note that during the passivation process, the passivation solution of this embodiment is consistent with the passivation process of TTA passivation solution 1 and BTA passivation solution 2 on the market, including the initial state of the sample, passivation time, passivation temperature and passivation method.

[0057] The samples passivated with the three passivation solutions were subjected to salt water immersion test analysis. The salt water immersion test can relatively accurately and truly reflect the corrosion resistance of the passivation film itself. The steps are to immerse it in a 5% NaCl solution for 48 hours, rinse and dry the corrosion products of the sample, and then weigh them. The corrosion weight loss or corrosion weight loss rate of the sample is calculated by the mass difference before and after the experiment. The specific values ​​are as follows in Table 3: Table 3 Corrosion weight loss of pure copper samples

[0058] It can be seen from the salt water immersion experiment that the passivation solution of this embodiment greatly improves the corrosion resistance of the sample when passivating pure copper, and the corrosion weight loss rate is only 31%~50% of the products on the market.

[0059] The passivation of the copper inner core (red copper material) of the cable using the passivation solution of this embodiment includes the following steps: S2.1. First, pickle and pre-treat the copper sample by pickling it in a 12% acetic acid solution for 15 seconds, then soak and clean it in deionized water, and then fully grind and observe the copper sample to ensure that the pollutants and oxide layer on the surface of the copper sample are removed; S2.2, the pretreated copper sample was placed in the passivation solution, TTA passivation solution 1 and BTA passivation solution 2 on the market, respectively, the passivation temperature was 60 ° C, the pH value was 10, and the passivation treatment time was 30s; S2.3, drying the copper sample treated in step S2.2 at a temperature of 100° C. to obtain a passivation film on the surface of the copper sample, thus completing the passivation.

[0060] The samples passivated with three kinds of passivation solutions were subjected to nitric acid spot test analysis, which can quickly detect the corrosion resistance of the samples. The steps are to drop 25% nitric acid solution on the surface of the passivated samples, corrode for 20 seconds, rinse and dry, and observe the changes in surface morphology, see Table 4: Table 4 Passivation solution corrosion results

[0061] It can be quickly and obviously seen from the nitric acid dripping experiment that after the passivation solution of the present invention passivates red copper, the corrosion resistance of the sample is greatly improved. When the nitric acid with a concentration of 25% is dripped and corroded for 20 seconds, there is almost no large blackboard and serious discoloration on the surface. The effect is better than the copper passivation solution on the market and almost reaches the effect of the chromate passivation solution.

[0062] Embodiment 3: A passivation solution is composed of the following components in terms of mass: 5 g of a benzotriazole derivative, 4 g of tolyltriazole, 6 g of cerium nitrate, 2 g of lanthanum nitrate powder, 5 g of boron powder, 20 ml of 30% hydrogen peroxide (2 g), and 1000 ml of deionized water.

[0063] The preparation method of the passivation solution comprises the following steps: S1.1, add 5 g of benzotriazole derivative powder into 500 mL of deionized water, stir evenly, then slowly add 6 g of tolyltriazole powder into the benzotriazole derivative solution, stir mechanically to mix well, and obtain solution A; S1.2. Use a heating furnace to keep the temperature of solution A at 50-60°C, add 5g of boron powder into solution A, stir evenly and dissolve the boron powder completely; S1.3. Add 6g of cerium nitrate and 2g of lanthanum nitrate powder into 500ml of deionized water and stir thoroughly to prepare solution B. Add 500ml of solution B and 20ml of 30% hydrogen peroxide into the solution after the boron powder is completely dissolved through a drainage rod. Stir at 90Hz for 4-6 minutes by ultrasonic vibration to form solution B to obtain the desired passivation solution.

[0064] The passivation of the copper inner core of the cable using the passivation solution of this embodiment includes the following steps: S2.1. First, pickle and pre-treat the pure copper sample by pickling it in a 7% acetic acid solution for 18 seconds, then soak and clean it in deionized water, and then fully grind and observe the pure copper sample to ensure that the pollutants and oxide layer on the surface of the pure copper sample are removed; S2.2, the pretreated pure copper sample was placed in the passivation solution, TTA passivation solution 1 and BTA passivation solution 2 on the market, respectively, the passivation temperature was 50 ° C, the pH value was 4, and the passivation treatment time was 60s; S2.3. Dry the pure copper sample treated in step S2.2 at a temperature of 60° C. to obtain a passivation film on the surface of the pure copper sample, thus completing the passivation.

[0065] Note that during the passivation process, the passivation solution of this embodiment is consistent with the passivation process of TTA passivation solution 1 and BTA passivation solution 2 on the market, including the initial state of the sample, passivation time, passivation temperature and passivation method.

[0066] The samples passivated with three kinds of passivation solutions were subjected to salt water immersion test analysis. The salt water immersion test can relatively accurately and truly reflect the corrosion resistance of the passivation film itself. The steps are to immerse it in 5% NaCl solution for 48 hours, rinse and dry the corrosion products of the sample and weigh them, and calculate the corrosion weight loss or corrosion weight loss rate of the sample by the mass difference before and after the experiment. The specific values ​​are as follows in Table 5: Table 5 Corrosion weight loss of pure copper samples

[0067] It can be seen from the salt water immersion experiment that the passivation solution of this embodiment greatly improves the corrosion resistance of the sample when passivating pure copper, and the corrosion weight loss rate is only 41%~50% of the products on the market.

[0068] The passivation of the copper inner core (red copper material) of the cable using the passivation solution of this embodiment includes the following steps: S2.1. First, pickle and pre-treat the copper sample by pickling it in a 7% acetic acid solution for 18 seconds, then soak and clean it in deionized water, and then fully grind and observe the copper sample to ensure that the pollutants and oxide layer on the surface of the copper sample are removed; S2.2, the pretreated copper sample was placed in the passivation solution, TTA passivation solution 1 and BTA passivation solution 2 on the market, respectively, the passivation temperature was 50°C, the pH value was 4, and the passivation treatment time was 60s; S2.3, drying the copper sample treated in step S2.2 at a temperature of 60° C. to obtain a passivation film on the surface of the copper sample, thus completing the passivation.

[0069] The samples passivated with three kinds of passivation solutions were subjected to nitric acid spot test analysis, which can quickly detect the corrosion resistance of the samples. The steps are to drop 25% nitric acid solution on the surface of the passivated samples, corrode for 20 seconds, rinse and dry, and observe the changes in surface morphology, see Table 6: Table 6 Passivation solution corrosion results

[0070] It can be quickly and obviously seen from the nitric acid dripping experiment that after the passivation solution of the present invention passivates red copper, the corrosion resistance of the sample is greatly improved. When the nitric acid with a concentration of 25% is dripped and corroded for 20 seconds, there is almost no large blackboard and serious discoloration on the surface. The effect is better than the copper passivation solution on the market and almost reaches the effect of the chromate passivation solution.

[0071] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A passivation solution, characterized in that: The invention is composed of the following components in the following mass percentages: 4.5-10.0% of a film-forming agent, 3.0-6.5% of an auxiliary film-forming agent, 0.5-15.0% of an oxidant, 2.5-6.5% of boron powder, and the rest is deionized water; the effective components of the film-forming agent are benzotriazole derivatives and tolyltriazole, the effective components of the auxiliary film-forming agent are cerium nitrate and lanthanum nitrate, and the effective component of the oxidant is sodium hypochlorite or hydrogen peroxide.

2. The passivation solution according to claim 1, wherein: The film-forming agent is a mixed solution consisting of benzotriazole derivatives, tolyltriazole and deionized water, wherein the mass ratio of the benzotriazole derivatives to tolyltriazole is 3-10:4-9.

5.

3. The passivation solution according to claim 1, wherein: The mass ratio of the cerium nitrate to the lanthanum nitrate is 0.5-1.5:0.5-1.

5.

4. A method for preparing a passivation solution according to any one of claims 1 to 3, characterized in that: The steps include: S1.1, add the formulated amount of benzotriazole derivative and tolyltriazole into deionized water, and stir evenly to form solution A; S1.

2. Add the formulated amount of boron powder into solution A, heat the mixture to target temperature 1, stir evenly and completely dissolve the boron powder; S1.

3. Add the auxiliary film-forming agent and oxidant in the formulated amount to the solution in which the boron powder is completely dissolved to form solution B. Stir solution B evenly and allow it to react fully at target temperature 2 to obtain a passivation solution.

5. A method for passivating a copper inner core of a cable using the passivation solution according to any one of claims 1 to 3, characterized in that: The steps include: S2.

1. First, the copper sample is pickled and surface pretreated to remove pollutants and oxide layers on the surface of the copper sample; S2.2, placing the pretreated copper sample into the passivation solution, the passivation temperature is 25-70°C, the pH value is 4-10, and the passivation treatment time is 30-150s; S2.3, drying the copper sample treated in step S2.2 at a temperature of 60-100° C. to obtain a passivation film on the surface of the copper sample, thus completing the passivation.

6. The passivation method according to claim 5, characterized in that: The step S2.2 requires that the copper sample be completely immersed during passivation and stirred using ultrasonic vibration.

7. The passivation method according to claim 5, characterized in that: The surface pretreatment includes grinding and pickling.

8. The passivation method according to claim 7, characterized in that: The pickling process requires that the copper sample be completely immersed and continuously shaken.

9. The passivation method according to claim 7, characterized in that: An acetic acid solution is used during the pickling.

10. The passivation method according to claim 9, characterized in that: In the acetic acid solution, the mass ratio of acetic acid to water is 1-3:15-25.

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