Refrigerator condenser dezincification process

Abstract

The invention discloses a refrigerator condenser dezincing process which comprises the steps that S1, a refrigerator condenser to be dezinced is immersed in a composite dezincing solution, the composite dezincing solution is composed of organic acid, a complexing agent, a corrosion inhibitor, a surfactant and water, the concentration of the organic acid is 50-80 g / L, the concentration of the complexing agent is 20-40 g / L, the concentration of the corrosion inhibitor is 5-15 g / L, and the concentration of the surfactant is 2-8 g / L; s2, under the condition that the temperature is 30-50 DEG C, the composite dezincification solution is subjected to ultrasonic stirring, the ultrasonic frequency is 20-40 kHz, and the stirring time is 15-30 minutes; s3, the condenser is taken out and washed with clear water, the washing pressure ranges from 0.2 MPa to 0.5 MPa, and the washing time ranges from 3 min to 5 min; and S4, the washed condenser is subjected to hot air drying, the hot air temperature ranges from 60 DEG C to 80 DEG C, and the drying time ranges from 10 min to 20 min.

Description

Technical Field

[0001] The invention relates to the technical field of condenser processing, and in particular to a zinc removal process for a refrigerator condenser. Background Art

[0002] The refrigerator condenser is a crucial component of the refrigerator's refrigeration system, and its performance directly impacts the refrigerator's cooling efficiency and energy consumption. During the manufacturing process, galvanizing is often used to improve the condenser's corrosion resistance. However, in certain subsequent processing or application scenarios, the zinc coating on the condenser surface must be removed.

[0003] Currently, common methods for removing zinc from refrigerator condensers include chemical etching and mechanical polishing. Chemical etching typically involves soaking the condenser in a strong acid solution, where the strong acid reacts with the zinc to remove the zinc layer. While this method is relatively simple to operate, it presents numerous problems. First, the strong acid solution lacks selectivity when it comes to corrosion of the zinc layer. While removing the zinc layer, it also severely corrodes the condenser's base metal, reducing its strength and service life. Second, the strong acid solution is highly corrosive, posing a significant safety hazard during operation and easily causing harm to operators. Furthermore, the strong acid solution is difficult to dispose of after use, causing significant environmental pollution.

[0004] Mechanical polishing removes the zinc layer from the condenser surface through physical friction. While this method is environmentally friendly, it can easily cause scratches and deformations on the condenser surface due to the difficulty in precisely controlling the polishing force and angle, affecting its appearance and performance. Furthermore, mechanical polishing is inefficient and cannot meet the needs of large-scale production.

[0005] Further in-depth analysis shows that the reason for the above-mentioned problems in the chemical corrosion method is that the chemical properties of the strong acid solution are too active. When reacting with zinc, it is impossible to accurately corrode only the zinc layer. Its strong oxidizing properties will also corrode the base metal. At the same time, the uncontrollability of the strong acid solution makes it difficult to effectively control the degree of reaction during the treatment process. The root cause of the problems with the mechanical polishing method is that the existing polishing equipment and processes make it difficult to achieve fine treatment of the condenser surface, and it is impossible to ensure that the zinc layer is removed without causing damage to the condenser base. In addition, the large amount of heat and friction generated during the mechanical polishing process will also have an adverse effect on the structure and performance of the condenser.

[0006] In order to solve these problems existing in the existing refrigerator condenser dezincification process, it is urgent to develop a new dezincification process that can not only remove the zinc layer efficiently and accurately, but also ensure that the condenser base is not damaged. At the same time, it must meet the requirements of environmental protection and safe production and improve production efficiency. Summary of the Invention

[0007] The present invention aims to provide a refrigerator condenser dezincification process, which should be able to remove the zinc layer efficiently and accurately while ensuring that the condenser base is not damaged. At the same time, it should also meet the requirements of environmental protection and safe production and improve production efficiency.

[0008] In order to achieve the above objectives, this application provides the following technical solutions:

[0009] A refrigerator condenser dezincification process comprises: S1, immersing the refrigerator condenser to be dezincified in a prepared composite dezincification solution, wherein the composite dezincification solution consists of an organic acid, a complexing agent, a corrosion inhibitor, a surfactant and water, wherein the organic acid concentration is 50-80 g / L, the complexing agent concentration is 20-40 g / L, the corrosion inhibitor concentration is 5-15 g / L, and the surfactant concentration is 2-8 g / L; S2, ultrasonically stirring the composite dezincification solution at a temperature of 30-50° C., with an ultrasonic frequency of 20-40 kHz and a stirring time of 15-30 minutes; S3, removing the condenser and rinsing it with clean water at a rinsing pressure of 0.2-0.5 MPa and a rinsing time of 3-5 minutes; S4, drying the rinsed condenser with hot air at a hot air temperature of 60-80° C. and a drying time of 10-20 minutes.

[0010] Optimally, the volume ratio of the organic acid, complexing agent, corrosion inhibitor, surfactant and water is: 5-8: 2-4: 0.5-1.5: 0.2-0.8: 85-92.

[0011] Optimally, the organic acid is a mixture of one or more of citric acid, oxalic acid or tartaric acid.

[0012] Optimally, the complexing agent is ethylenediaminetetraacetic acid and its salts.

[0013] Optimally, the corrosion inhibitor is hexamethylenetetramine.

[0014] Optimally, the surfactant is sodium dodecylbenzenesulfonate.

[0015] The optimization also includes S5, applying a directional electric field during the zinc removal process, the direction of the electric field is perpendicular to the surface of the zinc layer, and the electric field strength is 0.5 to 2 kV / m.

[0016] The optimization also includes S6, electrochemical regeneration of the used composite zinc removal solution, through the titanium-based lead dioxide electrode and stainless steel cathode set in the solution tank, at a current density of 10 to 20 mA / cm 2 , electrolysis is carried out under the condition of a voltage of 3 to 5 V, so that the zinc ions in the solution are reduced and deposited at the cathode, and the organic acid and complexing agent are regenerated at the same time.

[0017] Optimally, the directional electric field is generated by an anode plate and a cathode plate, wherein the anode plate is arranged opposite to the condenser surface and the cathode plate is located at the bottom of the condenser.

[0018] Working principle and beneficial effects of the present invention:

[0019] Citric, oxalic, or tartaric acid organic acids ionize hydrogen ions in the solution, reacting chemically with zinc to dissolve the zinc layer. Compared to traditional strong acids, these organic acids are relatively weaker and more selective, reacting preferentially with zinc while having less corrosive effects on the condenser's base metal. Ethylenediaminetetraacetic acid and its salts act as chelating agents, reacting with zinc ions to form stable complexes. This complexing reaction has a large equilibrium constant, which promotes the continued dissolution of the zinc layer while reducing the concentration of free zinc ions in the solution and the potential corrosion of the zinc ions on the base metal. Hexamine adsorbs on the surface of the condenser's base metal, forming a dense protective film. This protective film prevents hydrogen ions, zinc ions, and other ions in the solution from directly contacting the base metal, thereby effectively inhibiting corrosion of the base metal and protecting the structural strength and performance of the condenser. Sodium dodecylbenzenesulfonate, as a surfactant, can significantly reduce the surface tension of the solution and enhance the solution's ability to wetting and penetrate the surface of the zinc layer. It can enable the composite dezincification solution to better adhere to the surface of the zinc layer and penetrate into the tiny pores and defects of the zinc layer, making the dezincification reaction more complete.

[0020] Ultrasonic stirring at a frequency of 20 to 40 kHz at temperatures between 30 and 50°C creates a cavitation effect as the ultrasound propagates through the solution. Countless tiny bubbles form and grow under the influence of the ultrasound before suddenly bursting, generating intense shock waves and microjets. These shock waves and microjets destroy the passivation film on the zinc layer, accelerating the chemical reaction between the zinc layer and the composite dezincification solution, and increasing the dezincification rate. Furthermore, ultrasonic stirring evenly distributes the various components in the solution across the condenser surface, ensuring consistent dezincification results.

[0021] The synergistic effect of the various components of the composite dezincification solution and the enhanced ultrasonic agitation enable rapid and precise removal of the zinc layer from refrigerator condensers. Compared to traditional processes, this process improves dezincification efficiency by 30% to 50%, while ensuring uniform zinc removal, meeting the requirements for dezincification of refrigerator condensers of varying sizes and shapes. DETAILED DESCRIPTION

[0022] The following is further described in detail through specific implementation methods:

[0023] Example 1: A refrigerator condenser dezincification process, comprising: S1, immersing the refrigerator condenser to be dezincified in a prepared composite dezincification solution, wherein the composite dezincification solution is composed of an organic acid, a chelating agent, a corrosion inhibitor, a surfactant and water, wherein the organic acid concentration is 60 g / L, the chelating agent concentration is 30 g / L, the corrosion inhibitor concentration is 10 g / L, and the surfactant concentration is 6 g / L; S2, ultrasonically stirring the composite dezincification solution at a temperature of 45°C, with an ultrasonic frequency of 30 kHz and a stirring time of 20 minutes; S3, removing the condenser and rinsing it with clean water at a rinsing pressure of 0.3 MPa and a rinsing time of 4 minutes; S4, drying the rinsed condenser with hot air at a hot air temperature of 70°C and a drying time of 15 minutes.

[0024] The volume ratio of the organic acid, complexing agent, corrosion inhibitor, surfactant and water is 5:2:0.5:0.2:85. The organic acid is citric acid, the complexing agent is ethylenediaminetetraacetic acid, the corrosion inhibitor is hexamethylenetetramine, and the surfactant is sodium dodecylbenzenesulfonate.

[0025] The following comparative experiment was designed based on Example 1. Except for the following data differences, the rest of the data are the same as those in Example 1:

[0026] Example 2: Citric acid was replaced with oxalic acid;

[0027] Example 3: Citric acid was replaced with tartaric acid;

[0028] Example 4: The volume ratio of organic acid, complexing agent, corrosion inhibitor, surfactant and water is: 8:4:1.5:0.8:92.

[0029] Example 5: The volume ratio of organic acid, complexing agent, corrosion inhibitor, surfactant and water is: 7:3:1:0.6:90.

[0030] Example 6: The organic acid concentration is 50 g / L, the complexing agent concentration is 20 g / L, the corrosion inhibitor concentration is 5 g / L, and the surfactant concentration is 2 g / L

[0031] Example 7: The organic acid concentration is 80 g / L, the complexing agent concentration is 40 g / L, the corrosion inhibitor concentration is 15 g / L, and the surfactant concentration is 8 g / L.

[0032] Example 8: The composite dezincification solution consists of an organic acid, a complexing agent, a corrosion inhibitor and water.

[0033] Example 9: The composite dezincification solution consists of an organic acid, a complexing agent, a surfactant and water.

[0034] Example 10: The composite dezincification solution consists of an organic acid, a corrosion inhibitor, a surfactant and water.

[0035] Comparative Example 1: Prepare a 10% hydrochloric acid solution, immerse the condenser in it, and allow it to stand in a constant temperature water bath at 45°C for 20 minutes. Remove the condenser and rinse it with clean water at a pressure of 0.3 MPa for 4 minutes. Dry the rinsed condenser in a hot air drying oven at 70°C for 15 minutes.

[0036] Comparative Example 2: Initially sand the condenser using 80-grit sandpaper to remove most of the zinc layer. Then, fine sand the condenser using 120-grit, 200-grit, and 400-grit sandpaper, for a total of 20 minutes. Rinse the condenser with clean water at 0.3 MPa for 4 minutes to remove sanding debris. Dry the rinsed condenser in a 70°C hot air drying oven for 15 minutes.

[0037] Blank control group: Immerse the condenser in an equal amount of deionized water and place it in a constant temperature water bath at 45°C for 20 minutes without ultrasonic agitation. Remove the condenser and rinse it with clean water at a pressure of 0.3 MPa for 4 minutes. Dry the rinsed condenser in a hot air drying oven at 70°C for 15 minutes.

[0038] Test method: After drying, the condenser was weighed again, and the difference in mass before and after zinc removal was calculated to determine the amount of zinc removed. The remaining zinc layer thickness was measured (measured at five different locations on each condenser and the average value was taken). The condenser surface microstructure was observed using a metallographic microscope, and the corrosion rate of the condenser substrate was measured using an electrochemical workstation. The above data are shown in Table 1:

[0039]

[0040]

[0041] Effect of organic acid type: Comparison of Examples 1 to 3 shows that when citric acid is used as the organic acid, the zinc layer removal amount is relatively high, the substrate corrosion rate is low, and the surface microstructure is optimal, indicating that citric acid has the best zinc removal effect in this process.

[0042] Influence of component volume ratio: In Examples 4 and 5, after adjusting the component volume ratio, the zinc layer removal amount increased without significantly increasing the substrate corrosion rate, indicating that a suitable component volume ratio can further optimize the zinc removal effect.

[0043] Effect of concentration of each component: Examples 6 and 7 show that increasing the concentration of each component within a certain range can increase the amount of zinc layer removed, but the concentration change has little effect on the corrosion rate of the substrate.

[0044] Effect of the presence or absence of each component: In Examples 8 to 10, when the surfactant, corrosion inhibitor or chelating agent is missing, the amount of zinc layer removed is reduced, the substrate corrosion rate is significantly increased, and the surface microstructure deteriorates, indicating that each component in the composite dezincification solution is indispensable and can only achieve a good dezincification effect through synergistic action.

[0045] Compared with existing technologies:

[0046] Zinc removal efficiency: The zinc layer removal amounts of Examples 1 to 7 in this process are generally higher than those of the chemical etching method and the mechanical polishing method, especially the zinc layer removal amount of Example 7 reaches 40.5±2.5 mg, which is significantly better than the prior art.

[0047] Substrate protection: The substrate corrosion rate of chemical etching method is as high as 1.2±0.08mg / (cm 2 ·h), mechanical polishing method also reached 0.6±0.05mg / (cm 2 ·h), and the substrate corrosion rate of this process is basically controlled at 0.3~0.5mg / (cm 2 h), the protection effect on the substrate is significantly better than the existing technology.

[0048] Surface quality: The surface of the condenser treated by chemical etching is severely corroded, with a large number of deep pits and cracks; the surface treated by mechanical polishing has obvious scratches and local deformation; the surface of the condenser treated by this process is relatively flat, with a better microstructure, which is more conducive to subsequent processing and use.

[0049] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A process for removing zinc from a refrigerator condenser, characterized in that: include: S1. Immerse the refrigerator condenser to be dezincified in a composite dezincification solution, wherein the composite dezincification solution consists of an organic acid, a chelating agent, a corrosion inhibitor, a surfactant and water, wherein the organic acid concentration is 50-80 g / L, the chelating agent concentration is 20-40 g / L, the corrosion inhibitor concentration is 5-15 g / L, and the surfactant concentration is 2-8 g / L; S2. Ultrasonic stirring is performed on the composite dezincification solution at a temperature of 30-50° C., the ultrasonic frequency is 20-40 kHz, and the stirring time is 15-30 minutes; S3. Take out the condenser and rinse it with clean water at a rinsing pressure of 0.2-0.5 MPa and a rinsing time of 3-5 minutes; S4. Dry the rinsed condenser with hot air at a hot air temperature of 60-80° C. and a drying time of 10-20 minutes.

2. The refrigerator condenser dezincification process according to claim 1, characterized in that: The volume ratio of the organic acid, the complexing agent, the corrosion inhibitor, the surfactant and water is: 5-8: 2-4: 0.5-1.5: 0.2-0.8: 85-92.

3. The refrigerator condenser dezincification process according to claim 2, characterized in that: The organic acid is a mixture of one or more of citric acid, oxalic acid or tartaric acid.

4. The refrigerator condenser dezincification process according to claim 3, characterized in that: The complexing agent is ethylenediaminetetraacetic acid and its salts.

5. The refrigerator condenser dezincification process according to claim 4, characterized in that: The corrosion inhibitor is hexamethylenetetramine.

6. The refrigerator condenser dezincification process according to claim 5, characterized in that: The surfactant is sodium dodecylbenzenesulfonate.

7. The refrigerator condenser dezincification process according to claim 6, characterized in that: The method further includes S5, applying a directional electric field during the zinc removal process, wherein the direction of the electric field is perpendicular to the surface of the zinc layer and the electric field strength is 0.5 to 2 kV / m.

8. The refrigerator condenser dezincification process according to claim 7, characterized in that: The invention also includes S6, electrochemically regenerating the used composite zinc removal solution, through the titanium-based lead dioxide electrode and stainless steel cathode set in the solution tank, at a current density of 10 to 20 mA / cm 2 , electrolysis is carried out under the condition of a voltage of 3 to 5 V, so that the zinc ions in the solution are reduced and deposited at the cathode, and the organic acid and complexing agent are regenerated at the same time.

9. The process for removing zinc from a refrigerator condenser according to any one of claims 1 to 8, characterized in that: The directional electric field is generated by an anode plate and a cathode plate. The anode plate is arranged opposite to the surface of the condenser, and the cathode plate is located at the bottom of the condenser.

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