A process for high-efficiency cleaning and conversion film integrated treatment of pre-plated nickel steel shell surface

Abstract

This invention relates to an integrated process for efficient cleaning and conversion coating of pre-plated nickel steel shells, comprising the following steps: Step 1: Dissolving the following components (by mass concentration) in deionized water: organic acid, zirconium salt, titanium salt, oxidant, film-forming promoter, surfactant, and defoamer, and adjusting the pH to 4.5–5.2; Step 2: Immersing the stamped pre-plated nickel steel shell in the integrated treatment working solution, treating it at 40–60°C for 120–300 seconds, supplemented by ultrasonic oscillation or spray agitation, simultaneously completing the degreasing and cleaning of the steel shell surface and the deposition of the zirconium-titanium composite conversion film; Step 3: Removing the treated steel shell and rinsing it with deionized water to remove residual working solution; Step 4: Drying the washed steel shell at 80–120°C to obtain a finished pre-plated nickel steel shell with a composite conversion film on its surface. This invention offers the advantages of integrated treatment, high cleanliness and corrosion resistance, environmental safety and compliance, process compatibility, and reduced production costs.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, and in particular to an integrated process for efficient cleaning and conversion coating of pre-nickel-plated steel shell surface. Background Technology

[0002] With the rapid development of the high-end cylindrical lithium battery industry, pre-plated nickel steel shells have become the preferred material for power battery and energy storage battery shells due to their excellent corrosion resistance, conductivity and weldability. The surface treatment process of the steel shell after stamping and stretching directly determines the protective performance, processing adaptability and final service life of the battery shell, and is one of the key processes in the battery manufacturing process.

[0003] Currently, the industry generally adopts a step-by-step surface treatment process. This involves first using a strong alkaline degreasing agent to degrease and clean the steel casing multiple times, followed by multiple water rinses before entering the passivation process to complete the conversion film preparation. Some processes also include an additional rust-prevention treatment step, and most companies still use chromate passivation systems containing hexavalent chromium to ensure the corrosion resistance of the film. This step-by-step processing mode has many unavoidable technical shortcomings. On the one hand, the process chain is lengthy, requiring multiple workpiece transfers and drying processes, significantly increasing equipment investment costs and workshop floor space, lengthening the production cycle, and making it difficult to adapt to the high-speed, large-scale battery casing production demands. On the other hand, traditional alkaline cleaning has limited ability to remove residual stretching oil and fine particles from stamping, resulting in high residual oil content on the surface, which directly hinders the uniformity of subsequent film formation reactions, leading to uneven conversion film thickness and insufficient adhesion. Furthermore, residual alkaline degreasing agent easily contaminates the subsequent passivation solution, causing pH fluctuations and decomposition of active ingredients. Therefore, multiple water rinsing processes are necessary, which in turn leads to… The large volume of production wastewater increases environmental treatment costs. Furthermore, the passivation process containing hexavalent chromium poses a strong carcinogenic risk and fails to comply with international environmental regulations such as RoHS and REACH, resulting in significant environmental governance pressure. Moreover, existing processes generally only focus on the corrosion resistance of the membrane itself, neglecting the membrane's compatibility with subsequent battery assembly processes such as laser welding and electrolyte wetting. Poor conductivity in some membrane layers can reduce welding strength, and residual surface additives can affect electrolyte wetting. Additionally, the cleaning solutions, passivation solutions, and rust inhibitors in existing processes often come from different suppliers, lacking a systematic formulation matching design. This leads to frequent interface problems at process connections, a narrow process window, and difficulty in controlling quality stability during continuous production. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide an integrated process for efficient cleaning and conversion coating of pre-nickel-plated steel shells, which offers advantages such as integrated processing, high cleanliness and corrosion resistance, environmental safety and compliance, process compatibility, and reduced production costs.

[0005] The above-mentioned objective of this invention is achieved through the following technical solutions: A high-efficiency cleaning and conversion coating integrated process for pre-nickel-plated steel shell surfaces includes the following steps: Step 1: Prepare the integrated treatment working solution: Dissolve the following components at the following mass concentrations in deionized water: organic acid 5-20 g / L, zirconium salt 2-10 g / L, titanium salt 1-5 g / L, oxidant 1-3 g / L, film-forming promoter 2-8 g / L, surfactant 0.5-3 g / L, defoamer 0.1-0.5 g / L, and adjust the pH value to 3.5-5.0; Step 2, Integrated treatment: Immerse the stamped pre-nickel-plated steel shell in the integrated treatment working solution and treat it at a temperature of 40-60°C for 120-300 seconds. The treatment process is supplemented by ultrasonic oscillation or spray stirring, and the degreasing and cleaning of the steel shell surface and the deposition of zirconium-titanium composite conversion film are completed simultaneously. Step 3, Water washing: Remove the treated steel shell and wash it with deionized water to remove any residual working solution from the surface; Step 4: Drying: Dry the washed steel shell at 80-120℃ to obtain a pre-plated nickel steel shell with a composite conversion film on the surface.

[0006] The above technical solution integrates cleaning and degreasing with chemical conversion film formation into a single step, eliminating the need for separate processing and intermediate transfers, thus significantly shortening the production process, reducing equipment footprint and energy consumption. At the same time, the weakly acidic compound system promotes the mutual development of cleaning and film formation, resulting in less residual oil on the workpiece surface, a uniform and dense film layer with strong adhesion, and excellent corrosion resistance. The entire process is free of harmful substances such as hexavalent chromium, making it environmentally compliant and significantly reducing wastewater discharge.

[0007] As a further technical solution of the present invention: the organic acid mentioned in step one is selected from one or more of citric acid, tartaric acid, malic acid, and gluconic acid.

[0008] Through the above technical solution, the selected hydroxy organic acid can efficiently complex metal ions in the drug solution and precisely control the film formation rate. At the same time, it can gently activate the surface of the pre-plated nickel steel shell, which not only avoids strong acid corrosion of the nickel plating layer, but also helps to peel off the slight oxide layer and contaminants on the surface, further improving the adhesion between the film layer and the substrate.

[0009] As a further technical solution of the present invention: the zirconium salt in step one is selected from one or more of fluorozirconic acid, potassium fluorozirconate, and ammonium fluorozirconate; the titanium salt is selected from one or more of fluorotitanic acid, potassium fluorotitanic acid, and ammonium fluorotitanic acid.

[0010] Through the above technical solution, fluorine-based zirconium salts and titanium salts work synergistically to form a ZrO2-TiO2 composite conversion film on the steel shell surface. The film is dense and uniform, chemically inert, and can effectively block the penetration of corrosive media. Its corrosion resistance is better than that of a single zirconium salt or titanium salt film. At the same time, the film thickness is controllable and has good conductivity, so it will not have an adverse effect on the subsequent laser welding process of the steel shell.

[0011] As a further technical solution of the present invention: the oxidant in step one is one or more of hydrogen peroxide, persulfate, and perborate; the film-forming promoter is one or more of sodium fluoride, potassium fluoride, and ammonium fluoride.

[0012] Through the above technical solutions, the oxidant can promote the rapid oxidation of nickel surface to form film-forming activation sites and accelerate the film-forming reaction rate; the fluoride film-forming promoter can assist the uniform hydrolysis deposition of zirconium titanium salt, improve the film density and smoothness, and the combination of the two can shorten the processing time and broaden the process temperature window.

[0013] As a further technical solution of the present invention: the surfactant mentioned in step one is a nonionic surfactant, selected from one or more of fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether.

[0014] The above technical solution utilizes a nonionic surfactant with strong emulsification and penetration capabilities, which can efficiently remove stretching oil stains and fine particles from the steel shell surface, improving surface cleanliness. At the same time, its low-foaming properties can be used in conjunction with defoamers to suppress foam generation during the treatment process. Furthermore, it has good compatibility with the film-forming system, does not interfere with the film-forming reaction, and is easily removed by water washing.

[0015] As a further technical solution of the present invention: the integrated treatment in step two adopts a spray and ultrasonic composite treatment method: first spray treatment for 30 to 60 seconds, and then ultrasonic immersion treatment for 90 to 240 seconds.

[0016] The above technical solution employs a step-by-step combined spraying and ultrasonic treatment method. First, large particulate contaminants on the steel shell surface are removed by spraying. Then, the cavitation effect and micro-jet action of ultrasonic waves are used to clean residual oil and dust in dead corners such as gaps and blind holes in the steel shell, achieving deep cleaning. At the same time, it can enhance the mass transfer effect of the solution on the workpiece surface and improve the uniformity and batch consistency of the conversion film.

[0017] As a further technical solution of the present invention, it also includes step five, rust prevention treatment: after drying in step four, the steel shell is dipped or sprayed with rust inhibitor, and then dried to form a rust-proof film.

[0018] By adding a rust prevention treatment process to the conversion film, a thin nano-level rust prevention film can be formed on the steel shell surface, which further improves the steel shell's salt spray resistance and oxidation resistance, and extends the rust prevention cycle during the storage and transportation of the workpiece; at the same time, the rust prevention film is thin and has good compatibility, and will not affect subsequent battery assembly processes such as welding and electrolyte injection.

[0019] As a further technical solution of the present invention: during the use of the integrated treatment working fluid, the component concentration is maintained stable through an online monitoring and automatic replenishment system, and the conductivity change of the working fluid is controlled to not exceed 15%.

[0020] By employing the above technical solutions, the working fluid is controlled through online monitoring and automatic replenishment, keeping the conductivity variation within 15%. This maintains the dynamic stability of the concentration of the drug components, ensuring consistent processing quality for each batch of steel shells in continuous mass production. It also avoids fluctuations in membrane performance caused by drug decay, extends the service life of the working fluid, and reduces production and maintenance costs.

[0021] The present invention also discloses an integrated treatment working solution for the above-described process, wherein the working solution is composed of the following components dissolved in deionized water at the following mass concentrations: organic acid 5-20 g / L, zirconium salt 2-10 g / L, titanium salt 1-5 g / L, oxidant 1-3 g / L, film-forming promoter 2-8 g / L, surfactant 0.5-3 g / L, and defoamer 0.1-0.5 g / L; and the pH value of the working solution is 3.5-5.0.

[0022] The integrated treatment working fluid obtained through the above technical solution combines degreasing and cleaning, surface activation and chemical film formation functions. The system is stable and the components are highly compatible. There is no need to prepare cleaning and passivation solutions in steps. A single tank can complete the surface treatment of the steel shell. The solution is chromium-free and environmentally friendly, and the wastewater treatment is easy. It is compatible with various treatment methods such as immersion, spraying and ultrasonic treatment, and can meet the needs of industrial production of different scales.

[0023] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention discloses an integrated process for efficient cleaning and conversion coating of pre-nickel-plated steel shells. The process involves a single-step treatment of the pre-nickel-plated steel shells using a weakly acidic compound working solution, simultaneously completing degreasing cleaning and zirconium-titanium composite conversion coating formation. This significantly shortens the production process, reduces wastewater discharge, and improves surface cleanliness and film corrosion resistance, while meeting chromium-free environmental compliance requirements.

[0024] 2. This invention discloses an integrated working fluid for efficient cleaning and conversion film formation on the surface of pre-nickel-plated steel shells. The integrated working fluid system is a weakly acidic mixture of organic acids, zirconium salts, titanium salts, oxidants, surfactants, and other components in proportion. It achieves multi-functional integration of degreasing cleaning, surface activation, and chemical film formation. The components are highly compatible and the system is stable. The steel shell surface treatment can be completed in a single tank. It is chromium-free, environmentally friendly, and compatible with various industrial processing methods. Attached Figure Description

[0025] Figure 1 The image shows the surface SEM morphology (5000x magnification) of the conversion film prepared in Example 1 of this invention. Figure 2 This is a TEM image of the cross-section of the conversion membrane prepared in Example 1 of the present invention.

[0026] Figure 3 This is a comparison chart of the salt spray test results of Example 1 and Comparative Example 1 of the present invention (surface state after 72 hours).

[0027] Figure 4 The image shows the EDS elemental analysis spectrum of the steel shell surface after processing in Example 1 of the present invention, which shows that Zr and Ti elements are uniformly distributed on the surface. Detailed Implementation

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0029] In the description of this application, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Example

[0031] This embodiment discloses an integrated process for high-efficiency cleaning and conversion coating of pre-nickel-plated steel shell surfaces, comprising the following steps: Step 1: Preparation of integrated treatment solution: Based on 1L of deionized water, add 12g of citric acid, 6g of fluorozirconic acid (calculated as zirconium), 3g of fluorotitanic acid (calculated as titanium), 2g of hydrogen peroxide, 4g of sodium fluoride, 1.5g of AEO-9, and 0.2g of organosilicon defoamer. Stir until all components are completely dissolved, and then adjust the pH of the system to 4.2 using ammonia.

[0032] Step 2, Integrated Processing: The pre-nickel-plated steel shell is completely immersed in the above working solution, and the processing temperature is controlled at 50℃ for 180 seconds. During the processing, 40kHz ultrasound with a power density of 0.5W / cm² is used to simultaneously complete degreasing cleaning and conversion film formation.

[0033] Step 3, water washing: Take out the treated steel shell, first spray it with deionized water for 30 seconds, then immerse it in deionized water for 30 seconds to completely remove the residual working fluid on the surface.

[0034] Step 4: Drying: Place the washed steel shell in a hot air drying device and dry it at 100°C for 15 minutes to obtain the finished steel shell.

[0035] The film layer of the finished steel shell prepared in this embodiment was characterized: Reference Figure 1 The SEM image (5000x magnification) of the conversion membrane surface shows that the membrane layer is uniform and dense, without cracks or defects.

[0036] Reference Figure 2 TEM images of the cross-section of the conversion membrane show that the membrane is about 120 nm thick, tightly bonded to the substrate, and without obvious delamination.

[0037] Reference Figure 4 XPS elemental analysis of the steel shell surface showed that Zr and Ti elements were uniformly distributed on the film surface, confirming the successful and uniform deposition of the zirconium-titanium composite conversion film. Example

[0038] An integrated process for high-efficiency cleaning and conversion coating of pre-nickel-plated steel shell surface is disclosed. The difference between this embodiment and Embodiment 1 lies in the working solution formulation in step one and the treatment method in step two. All other steps and parameters are consistent with Embodiment 1, with specific adjustments as follows: Step 1: Preparation of integrated treatment solution: Using deionized water as solvent, add 15g / L tartaric acid, 8g / L potassium fluorozirconate (calculated as zirconium), 4g / L potassium fluorotitanate (calculated as titanium), 2.5g / L sodium persulfate, 5g / L ammonium fluoride, OP-10 2g / L, and 0.3g / L polyether defoamer according to the mass concentration. After stirring and dissolving, adjust the pH of the system to 4.5 with citric acid.

[0039] Step 2, Integrated Processing: The pre-nickel-plated steel shell is sent to the processing station and first sprayed with 0.2MPa pressure for 45 seconds to remove large particulate contaminants from the surface. Then, it is immersed in the working solution for ultrasonic impregnation for 150 seconds. The ultrasonic frequency is 28kHz and the power density is 0.8W / cm². The processing temperature is controlled at 50℃ throughout the process, and degreasing and cleaning and conversion film formation are completed simultaneously. Example

[0040] An integrated process for high-efficiency cleaning and conversion coating of pre-nickel-plated steel shell surface is disclosed. The difference between this embodiment and Embodiment 1 is the addition of step five, rust prevention treatment. Steps one through four are identical to those in Embodiment 1. The specific details of the new step are as follows: Step 5, Rust Prevention Treatment: Prepare an environmentally friendly water-based rust inhibitor using deionized water as the solvent, add 5g / L of carboxylic acid amines and 1g / L of benzotriazole, and stir well; immerse the dried steel shell from Step 4 in the rust inhibitor for 60 seconds, remove it, and dry it with hot air at 80℃ for 5 minutes to form a nano-level rust-preventive film on the surface, thus obtaining the final product. Example

[0041] An integrated process for high-efficiency cleaning and conversion coating of pre-nickel-plated steel shell surface is disclosed. The difference between this embodiment and Embodiment 1 lies in the working solution formulation in step one. Steps two through four are completely identical to those in Embodiment 1. The adjusted step one is as follows: Step 1: Preparation of integrated treatment solution: Using deionized water as solvent, add malic acid 8g / L, gluconic acid 5g / L, ammonium fluorozirconate 5g / L (calculated as zirconium), ammonium fluorotitanate 2.5g / L (calculated as titanium), sodium perborate 1.5g / L, potassium fluoride 3g / L, AEO-7 1g / L, and organosilicon defoamer 0.15g / L according to the mass concentration. After stirring and dissolving, adjust the pH of the system to 3.8 with sodium hydroxide.

[0042] Comparative Example To verify the technical advantages of the process of this invention, three control processes were set up, with the same treatment objects as in the examples. The specific schemes are as follows: Comparative Example 1: The process adopts the industry's standard cleaning-passivation step-by-step process, which is as follows: alkaline degreasing agent cleaning (degreasing agent concentration 50g / L, treatment temperature 60℃, treatment time 5 minutes) → multiple water rinsing → chromate passivation solution treatment (passivation solution concentration 30g / L, treatment temperature 45℃, treatment time 3 minutes) → water rinsing → drying.

[0043] Comparative Example 2: The degreasing and cleaning steps are omitted. The pre-nickel-plated steel shell is directly treated with commercially available titanium-based chromium-free passivation solution at a temperature of 45°C for 3 minutes. After treatment, it is washed with water and dried.

[0044] Comparative Example 3: The same integrated treatment working solution and process parameters as in Example 1 were used, except that ultrasonic assistance was removed, and the immersion process without ultrasonic assistance was carried out; the static immersion method was used for 180 seconds, and the subsequent water washing and drying steps were the same as in Example 1.

[0045] Performance Testing and Result Analysis The steel shells treated according to Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to tests on multiple core indicators, including surface cleanliness, film performance, corrosion resistance, and weldability. The test results are shown in the table below: Surface residual oil content (mg / m²) 1.8 1.2 1.8 2.1 4.5 15.6 3.2 Particulate matter (20μm, per particle) 1 0 1 2 5 18 4 Film adhesion (cross-cut adhesion test) 5B 5B 5B 4B 4B 2B 4B Film thickness (nm) 120 150 120 90 80 Uneven 60 Neutral salt spray test (no red rust observed) 96 108 120 84 72 24 48 Electrochemical polarization resistance (Ω・cm²) 2.8 x 10 5 ]] 3.2 x 10 5 ]] 4.5 x 10 5 ]] 1.8 x 10 5 ]] 1.2 x 10 5 ]]> 3.5×10 7.5 x 10 4 ]] Welding performance (weld strength / N) 12.5 12.8 12.2 12.0 11.5 8.5 10.2 Total processing time (seconds) 180 195 240 180 480 180 180 Wastewater generation (L / 10,000 units) 50 50 60 50 200 30 50 Reference Figure 3 After 72 hours of neutral salt spray testing, no red rust was generated on the surface of the sample in Example 1, while obvious red rust appeared on the surface of the traditional process sample in Comparative Example 1, which directly demonstrates the significant improvement in corrosion resistance of this process.

[0046] Based on the test results, the following conclusions can be drawn: 1. The overall performance of Embodiments 1 to 4 of the present invention is significantly better than that of all comparative examples. They exhibit excellent performance in terms of surface cleanliness, film adhesion, corrosion resistance, and welding performance, and can meet the requirements for use in high-end cylindrical battery casings.

[0047] 2. Example 2 uses a spray + ultrasonic composite treatment method, which has the best surface cleanliness and better film uniformity and corrosion resistance; Example 3 adds a rust prevention treatment process, which has the best corrosion resistance and can achieve no red rust in neutral salt spray for up to 120 hours.

[0048] 3. The traditional step-by-step process in Comparative Example 1 has a long processing time and generates a large amount of wastewater, and its corrosion resistance is lower than that of all embodiments of the present invention. In Comparative Example 2, the cleaning step is omitted and the film is formed directly. The surface oil stains are serious and hinder the film formation reaction. The final film quality is extremely poor, and the corrosion resistance and adhesion are far below the qualified standard. In Comparative Example 3, without ultrasonic assistance, the surface cleaning effect and film uniformity are greatly reduced, which verifies the beneficial effect of ultrasonic enhancement on this process.

[0049] A long-term continuous operation stability test was conducted on the integrated treatment working fluid. The working fluid prepared in Example 1 was used as the test subject, and the continuous operation period was 30 days. The test conditions simulated a mass production continuous production line with a daily steel shell processing capacity of 500,000 units. An automatic fluid replenishment system was used to replenish the consumed components in real time to maintain the stability of the system formula. The pH value and conductivity of the working fluid were monitored online in real time throughout the process, and the neutral salt spray corrosion resistance of the corresponding steel shell finished products was tracked simultaneously.

[0050] The test results show that during the first 3 days of continuous operation, the pH value of the working solution was maintained stably in the range of 4.5 to 5.2, the conductivity was stably controlled at around 650 μS / cm, and the overall fluctuation of conductivity did not exceed 12%. The steel shells obtained by continuous treatment with this working solution had a stable neutral salt spray test duration of 120±8h and no significant fluctuations in corrosion resistance, which confirms that the working solution in this embodiment has excellent long-term stability for mass production.

[0051] Industrial Application Example: The spraying + ultrasonic composite process of Embodiment 2 of this invention was implemented on the 21700 pre-nickel-plated steel shell surface treatment production line of a battery shell manufacturing company. After 6 months of continuous and stable operation, the actual production data is as follows: Production efficiency: Single-shift output increased from 300,000 units to 500,000 units, representing a 66.7% increase in production efficiency; Product yield: The defect rate of surface treatment-related products decreased from 3.5% to 0.8%, a reduction of 77%; Energy consumption and emissions: The overall energy consumption per unit product is reduced by 45%, and the wastewater discharge is reduced from 20L / 10,000 units to 5L / 10,000 units, a reduction of 75%. Production costs: The cost of chemicals per unit product is reduced by 30%, wastewater treatment costs are reduced by 60%, and overall production costs are significantly reduced; Market validation: The steel-cased products produced by this process have passed the performance verification of leading battery companies, and the core indicators such as corrosion resistance and laser welding have all met the standards. Currently, they are being used in batches on high-end power battery production lines.

[0052] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high-efficiency cleaning and conversion film integrated treatment process for pre-nickel-plated steel shell surfaces, characterized in that, Includes the following steps: Step 1: Prepare the integrated treatment working solution: Dissolve the following components at the following mass concentrations in deionized water: organic acid 5-20 g / L, zirconium salt 2-10 g / L, titanium salt 1-5 g / L, oxidant 1-3 g / L, film-forming promoter 2-8 g / L, surfactant 0.5-3 g / L, defoamer 0.1-0.5 g / L, and adjust the pH value to 3.5-5.0; Step 2, Integrated treatment: Immerse the stamped pre-nickel-plated steel shell in the integrated treatment working solution and treat it at a temperature of 40-60°C for 120-300 seconds. The treatment process is supplemented by ultrasonic oscillation or spray stirring, and the degreasing and cleaning of the steel shell surface and the deposition of zirconium-titanium composite conversion film are completed simultaneously. Step 3, Water washing: Remove the treated steel shell and wash it with deionized water to remove any residual working solution from the surface; Step 4: Drying: Dry the washed steel shell at 80-120℃ to obtain a pre-plated nickel steel shell with a composite conversion film on the surface.

2. The integrated process for high-efficiency cleaning and conversion film treatment of pre-nickel-plated steel shell surface according to claim 1, characterized in that, The organic acid mentioned in step one is selected from one or more of citric acid, tartaric acid, malic acid, and gluconic acid.

3. The integrated process for high-efficiency cleaning and conversion film treatment of pre-nickel-plated steel shell surface according to claim 1, characterized in that, The zirconium salt mentioned in step one is selected from one or more of fluorozirconic acid, potassium fluorozirconate, and ammonium fluorozirconate; the titanium salt is selected from one or more of fluorotitanic acid, potassium fluorotitanic acid, and ammonium fluorotitanic acid.

4. The integrated process for high-efficiency cleaning and conversion film treatment of pre-nickel-plated steel shell surface according to claim 1, characterized in that, The oxidant mentioned in step one is one or more of hydrogen peroxide, persulfate, and perborate; the film-forming promoter is one or more of sodium fluoride, potassium fluoride, and ammonium fluoride.

5. The integrated process for high-efficiency cleaning and conversion film treatment of pre-nickel-plated steel shell surface according to claim 1, characterized in that, The surfactant mentioned in step one is a nonionic surfactant, selected from one or more of fatty alcohol polyoxyethylene ethers and alkylphenol polyoxyethylene ethers.

6. The integrated process for high-efficiency cleaning and conversion film treatment of pre-nickel-plated steel shell surface according to claim 1, characterized in that, The integrated treatment described in step two adopts a combined spray and ultrasonic treatment method: first, spray treatment is performed for 30 to 60 seconds, followed by ultrasonic immersion treatment for 90 to 240 seconds.

7. The integrated process for high-efficiency cleaning and conversion film treatment of pre-nickel-plated steel shell surface according to claim 1, characterized in that, It also includes step five, rust prevention treatment: after drying in step four, the steel shell is dipped or sprayed with rust inhibitor, and then dried to form a rust-proof film.

8. The integrated process for high-efficiency cleaning and conversion film treatment of pre-nickel-plated steel shell surface according to claim 1, characterized in that, During use, the integrated treatment working fluid maintains stable component concentration through online monitoring and automatic replenishment systems, and controls the conductivity change of the working fluid to not exceed 15%.

9. An integrated processing fluid for the process described in any one of claims 1-8, characterized in that, The working solution is composed of the following components dissolved in deionized water at the following mass concentrations: organic acid 5-20 g / L, zirconium salt 2-10 g / L, titanium salt 1-5 g / L, oxidant 1-3 g / L, film-forming promoter 2-8 g / L, surfactant 0.5-3 g / L, and defoamer 0.1-0.5 g / L; and the pH value of the working solution is 3.5-5.0.

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